Ebook Moss adams heart disease in infants, children, and adolescents Part 2

(BQ) Part 2 book Moss adams heart disease in infants, children, and adolescents presentation of content: Congenital cardiovascular malformations; diseases of the endocardium, myocardium, and pericardium, pulmonary vascular disease, the young adult with congenital heart disease, other special problems and issues.

Atrial septal defects (ASD) originate at particular sites in the

atrial septum and are named according to their embryonic

origin The most common occurs in the central part of the

atrial septum in the region of fossa ovalis (secundum ASD)

Others include those in the region of endocardial cushion

(pri-mum ASD), in the sinus venosus septum (sinus venosus ASD),

and in the region of ostium of coronary sinus (coronary sinus

ASD) In this chapter, we also address patent foramen ovale

(PFO), which is a normal interatrial communication present

in fetal life that may persist in adults Ostium primum ASD

is discussed in Chapter 29 since it is a part of the spectrum of

atrioventricular septal defects (AVSD)

INCIDENCE

ASDs constitute 8% to 10% of congenital heart defects in

chil-dren The incidence of ASDs has been estimated to be 56 per

100,000 live births (1) The recent estimates are much higher

(100 per 100,000 live births), likely due to increased

recog-nition of ASDs in this era of the common use of

echocardi-ography (2) The female:male ratio for secundum ASDs is

2:1, but for the sinus venosus ASDs it is 1:1 (3,4) Secundum

ASDs constitute approximately 75% of ASDs, followed by

ostium primum ASD (20%) and sinus venosus ASD (5%) (5)

Coronary sinus (CS) ASDs more often are seen in association

with heterotaxy syndromes and systemic venous anomalies, and isolated CS ASDs are rare (<1%)

GENETIC AND ENVIRONMENTAL RISK FACTORS

Although most ASDs occur sporadically, familial modes of inheritance have been reported The risk of congenital heart disease in offspring of a woman with a sporadic ASD is esti-mated to be 8% to 10% (6) ASDs may be related to mutations

in either regulatory genes or their target sarcomeric genes

Heterozygous mutations in the transcription factor NKX2.5/

CSX were among the fi rst found in families with autosomal dominant transmission of secundum ASDs (7) Mutations in other transcription factors such as TBX5, GATA4, GATA6, and TBX20 also have been associated with secundum ASDs (7–11) TBX5 mutations also are responsible for Holt-Oram syndrome, which is an autosomal dominant syndrome charac-terized by secundum ASD, anomalies of the upper extremities, and atrioventricular (AV) conduction delay (12) A locus on chromosome 14q12 with a missense mutation in alpha-myosin heavy chain (MYH6), a structural protein expressed at high levels in the developing atria, has been linked to dominantly inherited ASD (13) Secundum ASDs also have been reported

in association with cardiomyopathies that have resulted from mutations in sarcomeric genes (14,15) In ASDs associ-ated with prolonged AV conduction, an autosomal dominant pattern of inheritance has been reported (16) Secundum ASDs

Septal Defects

Congenital Cardiovascular Malformations

Ritu Sachdeva

Atrial Septal Defects

VI

CHAPTER

also are associated with other syndromes such as Noonan,

Down, Klinefelter, Williams, Kabuki, Goldenhar, and Ellis–

van Creveld In addition to genetic factors, maternal diseases

and exposure to environmental risk factors may play a role

in development of ASDs (17) These factors include

preges-tational diabetes, phenylketonuria, infl uenza and exposure to

retinoids, nonsteroidal anti-infl ammatory drugs,

anticonvul-sants, thalidomide, smoking, and alcohol (17–19)

PATHOGENESIS AND ANATOMIC FEATURES

During embryogenesis, the primitive atrium undergoes a

com-plex septation process (Fig 28.1) (20) In the fourth week of

embryonic life, the septum primum appears as a thin-walled

sagittal fold in the middle of the common atrium and grows

inferiorly toward the endocardial cushion The opening between

the leading edge of the septum primum and the endocardial

cushion is called the ostium primum Before complete closure

of the ostium primum, tissue reabsorption occurs in the

supe-rior portion of the septum primum resulting in another opening

called the ostium secundum This occurs during the fi fth and

sixth week of embryonic life Concurrently, an anterosuperior

infolding of the atrial roof develops to the right of the septum

primum, called the septum secundum that is concave shaped

with a superior and inferior limb The inferior limb fuses with

the lowermost part of the atrial septum to join the endocardial

cushion, thus separating the inferior portions of the two atria

The thick muscular ridge of the superior limb forms an

incom-plete partition that overlies the ostium secundum resulting in an

opening called the foramen ovale The septum secundum thus

forms the concave-shaped superior margin of the fossa ovalis,

called the limbus of fossa ovalis (annulus ovalis) and the

sep-tum primum forms the valve of fossa ovalis During fetal life,

inferior vena caval fl ow from the placenta is defl ected toward

the foramen ovale by the eustachian valve, and then blood is

directed from the right atrium to the left atrium via the foramen ovale This fetal interatrial communication (the PFO) normally closes after birth as a result of fusion of the septum primum and septum secundum However, it may persist in 25% to 30%

of adults where it is probe patent with a competent valve In some cases, the valve of fossa ovalis is incompetent, either con-genitally or acquired due to elevated right or left atrial pressures allowing interatrial shunting across the foramen

The atrial septal anatomy and location of various types

of ASDs are shown in Figure 28.2 Secundum ASDs occur in the central part of the atrial septum (fossa ovalis) as a result

of defi cient valve tissue, ectopic or excessive resorption of septum primum, or defi cient growth of septum secundum (Fig 28.3) Such defects result in an enlarged ostium secun-dum These defects usually are single, but rarely can occur as multiple atrial septal fenestrations

Sinus venosus defects occur outside the margins of the fossa ovalis, in relation to the venous connections of the right atrium (Fig 28.4) The right horn of sinus venosus incorporates the right superior vena cava (SVC) and inferior vena cava (IVC) into the right atrium Ectopic or incomplete resorption of the sinus venosus results in defi ciency of the wall that separates the right pulmonary veins from the SVC, IVC, and the right atrium resulting in a sinus venosus ASD (21) Some argue that these should be termed partial anomalous pulmonary venous return to the SVC The interatrial communication in these defects is, in fact, the orifi ce of the unroofed right pulmonary vein and is not a true defect in the atrial septum per se.(21) Most commonly, the sinus venosus ASDs are related to the SVC where blood from the right upper and/or middle pulmo-nary veins is directed into SVC or the right atrium Less fre-quently, a similar defect can occur inferior to the fossa ovalis

in relation to the IVC and the right lower pulmonary venous orifi ce This defect often has been termed an IVC-type sinus venosus ASD, although direct involvement of the IVC almost never occurs Hence, the term sinus venosus defect of right atrial type is preferred (21)

Figure 28.1. Schematic diagram showing embryogenesis of atrial septum LA, left atrium; LV, left ventricle; PFO, patent foramen ovale; RA, right atrium; RV, right ventricle (Modified from Van Mierop LHS Embryology of the atrioventricular canal region and pathogenesis of endocardial cushion defects In: Feldt RH, McGoon DC, Ong-

ley PA, et al., eds Atrioventricular Canal Defects Philadelphia, PA: WB Saunders, 1976:1–12, with permission.)

The left horn of the sinus venosus forms the CS The CS

defect (unroofed CS) results from failure of the wall between

the left atrium and CS to develop There may be complete or

partial unroofi ng of the CS resulting in direct communication

with the left atrium (Fig 28.5) Almost always, this anomaly

is associated with a left SVC A rare variation consists of

com-plete absence of the CS rather than unroofi ng, along with a

defect in the expected location of the ostium of CS In such

defects, blood from the left SVC directly enters the left atrium

Kirklin and Barratt-Boyes (5) classifi ed the unroofed CS defects

as type I, completely unroofed with LSVC; type II, completely

unroofed without LSVC; type III, partially unroofed

midpor-tion; and type IV, partially unroofed terminal portion

ASSOCIATED CARDIOVASCULAR ANOMALIES

Interatrial communications can occur in isolation, but often

are associated with other congenital heart defects The

pres-ence of an interatrial communication may be crucial for survival

in some such defects such as hypoplastic left heart syndrome,

D-transposition of great arteries, tricuspid atresia, and total

anom-alous pulmonary venous return Partial anomanom-alous pulmonary

venous return is present in almost 90% of patients with sinus venosus ASDs and, more rarely, can occur with secundum ASDs

Although valvular pulmonary stenosis frequently has been ciated with ASDs, the increased gradient across the pulmonary valve may be fl ow related and not necessarily due to an abnormal valve per se CS ASDs commonly are associated with a persistent left SVC Aside from congenital heart defects, secundum ASDs also have been reported in association with noncompaction and apical hypertrophic cardiomyopathy (14,15)

asso-Lutembacher Syndrome

Lutembacher syndrome is the association of an ASD with mitral stenosis Unlike the original description by Lutem-bacher, where the mitral stenosis was considered to be con-genital in origin, the current consensus is that it is of rheumatic origin (22) As a result of the mitral stenosis, the left-to-right shunting across the ASD is augmented The ASD usually is large and unrestrictive Therefore, the magnitude of the atrial level shunt is directly related to the degree of obstruction at the mitral valve Rarely, when the ASD is restrictive, the left-to-right shunt is continuous due to signifi cant pressure difference across the atrial septum during the entire cardiac cycle

Figure 28.2. A: Anatomy of the atrial septum View from the right atrial side B: View from the left atrial side

The interatrial septum (IAS) is outlined by the dotted lines It is formed by the limbus of the fossa ovalis on the right atrial side and the valve of the fossa ovalis toward the left The aortic root indents the right atrial free wall

anterosuperiorly as the torus aorticus (TA) C: Cross section of the heart in a 4-chamber view The IAS formed

by the limbus and valve of fossa ovalis lies between the right and left atria (RA, LA) The atrioventricular septum

(AVS) lies between the RA and left ventricle (LV) D: Schematic diagram showing the location of various types of

ASDs: (a) Secundum; (b) Primum, (c) Sinus venosus; (d) Coronary sinus IVC, inferior vena cava; IVS, tricular septum; MV, mitral valve; PT, pulmonary trunk; RAA, right atrial appendage; RV, right ventricle; SVC, superior vena cava; TV, tricuspid valve (Reprinted by permission of the Mayo Foundation.)

interven-A B

join the right atrium near the site of the ASD, posterior and superior to the fossa ovalis (FO) B: Right atrial view

The ASD is posterior to the FO, and the right upper and middle (RMPV) pulmonary veins are anomalously nected to the SVC Ao, aorta IVC, inferior vena cava; PT, pulmonary trunk; RAA, right atrial appendage; RV, right ventricle; SVC, superior vena cava; TV, tricuspid valve Reprinted by permission of the Mayo Foundation

con-675

Figure 28.3. Secundum ASD occurs in the region of fossa ovalis A: Right atrial view B: Left atrial view C:

Four-chamber view, showing comparison of a heart with large secundum ASD (arrows) with a normal heart (toward

the right) The right atrium (RA) and right ventricle (RV) are significantly enlarged in the heart with the ASD

D: Schematic diagram showing a left-to-right shunt across ASD, which becomes right-to-left with development

of pulmonary vascular disease Ao, aorta; LAA, left atrial appendage; IVC, inferior vena cava; MV, mitral valve;

PT, pulmonary trunk; RAA, right atrial appendage; RV, right ventricle; SVC, superior vena cava; TV, tricuspid valve (Reprinted by permission of the Mayo Foundation.)

During fetal life, the majority of the blood reaching the left

atrium comes via the foramen ovale since there is minimal fl ow

to the lungs After birth, the lungs expand and the pulmonary

blood fl ow increases The increased pulmonary venous return

to the left atrium results in the left atrial pressure exceeding

the right atrial pressure causing functional closure of the

fora-men ovale Intrauterine physiology is not altered in the

pres-ence of an ASD, but unlike the PFO, the ASD does not close

with the hemodynamic changes that occur following birth

The physiologic consequences of an ASD depend on the

mag-nitude and duration of the shunt and its interaction with the

pulmonary vascular bed The primary determinant of the

mag-nitude and direction of the shunt is the relative compliance

of the ventricles During the neonatal transition period as the

pulmonary vascular resistance drops and the right

ventricu-lar wall becomes thinner and hence more compliant than that

of the left ventricle, there is an increase in left-to-right

shunt-ing Catheter-based studies on fl ow dynamics in ASD provide

insight into the circulatory pattern during the various phases

of cardiac cycle Maximum left-to-right shunting occurs

dur-ing diastole when all four cardiac chambers are in

communica-tion Atrial contraction further augments this shunt A small

right-to-left shunt, predominantly from IVC blood can occur

during early diastole or during onset of systole The magnitude

and amount of shunting varies with the respiratory cycle

Dur-ing inspiration when the intrathoracic pressure is decreased,

there is a decrease in the left-to-right shunt across the ASD

Conversely, during expiration, when the intrathoracic pressure

is increased, there is an increase in the left-to-right shunt

Moderate-to-large left-to-right shunts across an ASD result

in volume overload and dilation of the right atrium and

ven-tricle (Fig 28.3) The tricuspid and pulmonary annuli may

dilate and become incompetent The volume-overloaded right

ventricle alters the diastolic confi guration of the left ventricle

with septal bowing toward the left Occasionally, the

abnor-mal left ventricular geometry may result in prolapse of the

mitral valve or superior systolic motion of the mitral leafl et (23) As a result of the increased fl ow into the lungs, the pul-monary arteries, capillaries, and the veins are dilated and there can be fl ow-related pulmonary artery hypertension Over time this can lead to medial hypertrophy of pulmonary arteries and muscularization of the arterioles resulting in pulmonary vascular obstructive disease (24,25) With severe pulmonary vascular obstructive disease, patients develop Eisenmenger syndrome as the atrial level shunt becomes right-to-left, result-ing in cyanosis (Fig 28.3)

CLINICAL PRESENTATION History

Most patients with ASD are asymptomatic and may remain undiagnosed until later in life They may come to medical attention due to abnormal auscultatory fi ndings or diagnostic studies such as ECG, chest radiograph, or echocardiogram

Very rarely, some infants with ASD may present with features

of pulmonary overcirculation, recurrent respiratory tions, and failure to thrive The mechanism of heart failure in these infants is not well understood since the hemodynamics are quite similar to those who are asymptomatic Some have proposed rapid remodeling and thinning of the pulmonary vascular bed to be the reason for this early presentation (26)

infec-Additionally, one should carefully evaluate mitral anatomy and function since mitral stenosis or regurgitation can aug-ment atrial shunting Despite repair of ASD in these patients, there may not be any signifi cant improvement in their symp-toms (27) Older children may present with symptoms of mild fatigue and dyspnea that may worsen with age In adults, worsening of clinical condition has been attributed to various factors such as a decrease in left ventricular compliance sec-ondary to coronary artery disease and hypertension, which, in turn, results in increased left-to-right shunt, right ventricular

Figure 28.5. Coronary sinus atrial septal defect (ASD) A: Right atrial view B: Left atrial view The defect is

at the site of the CS ostium, anterior and inferior to the fossa ovalis (FO) A persistent left superior vena cava (LSVC) joins the left atrial wall (LA) IVC, inferior vena cava; MV, mitral valve; RV, right ventricle; SVC, supe-rior vena cava; TV, tricuspid valve Reprinted by permission of the Mayo Foundation

failure, atrial arrhythmias, and elevated pulmonary artery

pressure Patients who develop Eisenmenger syndrome

(rever-sal of the left-to-right shunt due to pulmonary hypertension)

may present with cyanosis and syncope with exertion

Physical Examination

Phenotypic features of various syndromes associated with

ASD may be notable The most common syndrome known to

be associated with ostium secundum ASD is the Holt-Oram

syndrome In this syndrome, the thumb is hypoplastic and in

some cases may be rudimentary or absent Additionally, the

metacarpals may be small or absent and the radius may be

absent The thumb may resemble a fi nger

In patients with long-standing large left-to-right shunt,

there is a left precordial bulge Palpation reveals a prominent

right ventricular impulse felt along the lower left sternal

bor-der and the subcostal area In normal persons, splitting of

S2 has a normal variation with respiration During

inspira-tion, negative intrathoracic pressure causes increased venous

return into the right side of the heart, which in turn causes

the pulmonary valve to stay open for a longer duration in

ventricular systole causing a normal delay in the pulmonary

valve closure component of S2 During expiration, the positive

intrathoracic pressure reduces the venous return to the right

side of the heart, resulting in an earlier closure of pulmonary

valve The auscultatory hallmark of ASD is wide, fi xed

split-ting of the second heart sound (S2) This means that the aortic

and pulmonary components of S2 are widely separated during

expiration and demonstrate little or no variation in degree of

splitting during inspiration or with Valsalva maneuver S2 is

“widely split” due to a delay in closure of the pulmonary valve

resulting from prolonged emptying of the volume-overloaded

right ventricle and increased pulmonary vascular capacitance

leading to low pulmonary impedance and, therefore, a long

“hangout interval” after the end of right ventricular systole

The S2 is “fi xed” since the increased right ventricular stroke

volume does not vary much with respiration

A systolic ejection murmur can be heard in the left upper

parasternal area The murmur is due to increased fl ow across

the pulmonary valve This murmur begins shortly after S1 and

is crescendo–decrescendo, reaching its peak in early to

midsys-tole and ending before S2 When this murmur is loud, it can

indicate a large shunt or associated pulmonary valve stenosis

(a systolic ejection click usually is present when the nary valve is truly stenotic) When there is a large left-to-right shunt, a middiastolic murmur can be heard due to excessive

pulmo-fl ow across the tricuspid valve This murmur is short, soft, low to medium in frequency, and localized to the left lower parasternal area Rarely, a diastolic murmur may result from pulmonary regurgitation as a result of an exceptionally large pulmonary trunk that dilates the valve annulus

Most patients are acyanotic However, cyanosis can be seen

in those with pulmonary hypertension, signifi cant right tricular outfl ow tract obstruction, or in rare cases of a large eustachian valve directing IVC blood into the left atrium via the ASD Patients with pulmonary hypertension and a right-to-left atrial level shunt are cyanotic and have auscultatory

ven-fi ndings that are different from those of patients with an ASD without pulmonary hypertension The jugular venous pulse has a dominant “A” wave resulting from increased force of right atrial contraction The large “A” waves result in presys-tolic distention of the right ventricle resulting in a fourth heart sound The pulmonary component of S2 is loud and promi-nent The wide fi xed splitting of S2 and tricuspid fl ow mur-mur disappear and the midsystolic pulmonary fl ow murmur

is replaced by a softer and shorter murmur A high-frequency early diastolic murmur (Graham Steell murmur) of pulmonary regurgitation can be heard due to pulmonary valve incompe-tence resulting from pulmonary hypertension Also, a holo-sytolic S1 coincident murmur of tricuspid regurgitation heard best at the right lower sternal border can develop

DIAGNOSTIC EVALUATION Electrocardiogram and Electrophysiology

ECG fi ndings depend on the type and size of the ASD In patients with a small left-to-right shunt and no right atrial

or ventricular dilation, the ECG is normal With a signifi cant left-to-right shunt, an rSR′ pattern occurs in the right precordial leads indicating right ventricular volume overload (Fig 28.6) There often is slight prolongation of the QRS complex with slurring of the terminal R′, and the terminal forces are directed to the right, superiorly and anteriorly

-Other features include right axis deviation and tall P waves refl ecting right atrial enlargement In almost 50% of patients

terminal widening on S in lead V6 indicating right ventricular volume overload

with sinus venosus ASD, a frontal plane P wave axis of <30

degrees is seen (4) In most patients with ASD, the frontal

plane QRS axis is between +95 and +170 degrees Ostium

primum ASD can be distinguished from other forms of

ASDs by the presence of a counterclockwise loop and left

axis deviation Rhythm usually is sinus in children However,

older patients, usually beyond the third decade of life, can

have junctional rhythm or atrial arrhythmias such as atrial

fi brillation or fl utter (28) With the advent of pulmonary

hypertension, the rSR’ pattern in the right precordial leads

is replaced by Q waves and tall monophasic R waves with

deeply inverted T waves

Electrophysiologic studies have demonstrated a signifi cant

age-related incidence of sinus node dysfunction that may begin

in early childhood (29,30) These patients have prolonged

cor-rected sinus node recovery times and sinoatrial conduction

times (31) However, these fi ndings are not signifi cant

clini-cally and the resting and ambulatory ECGs in these patients

are normal AV node dysfunction is less common than sinus

node dysfunction Electrophysiologic studies in such cases

show a prolonged A-H interval or an AV node Wenckebach

periodicity at slow atrial pacing rates First-degree AV block

can occur in older individuals as a result of intraatrial H-V

conduction delay and in patients with a rare autosomal

domi-nant form of secundum ASDs (16)

Chest X-Ray

A small shunt across the ASD generally results in a

normal-appearing chest x-ray Cardiomegaly, due to right atrial and

right ventricular enlargement, and increased pulmonary

vas-cular markings extending to the periphery are seen in patients

with signifi cant shunts (Fig 28.7) The dilated right ventricle

occupies the apex and forms an acute angulation with the left

hemidiaphragm in the anteroposterior projection and

oblit-erates the retrosternal space in the lateral view Dilation of

the right ventricular outfl ow tract may cause smooth

continu-ity with the enlarged main pulmonary artery The proximal

branch pulmonary arteries, especially the right pulmonary

artery, also are dilated The left atrial and left ventricular sizes are normal If pulmonary hypertension develops, the increased peripheral pulmonary arterial vascularity is replaced

by oligemic lung fi elds

Echocardiogram

The echocardiogram is instrumental in defi ning the type of ASD, its size, the degree of shunting, its effect on the right-sided chambers of the heart, associated lesions, and estima-tions of right ventricular pressure These echocardiographic

fi ndings help in determining the appropriate intervention

Transthoracic Imaging

T WO -D IMENSIONAL I MAGING AND M-M ODE

An ASD can be visualized from the subcostal, parasternal, and apical views Subcostal views provide the best profi le of the atrial septum since the ultrasound beam is perpendicular to

it However, subcostal windows may be suboptimal in older

or obese patients In apical views, a “drop-out” may be seen

in the thin septal region of the fossa ovalis since the sound beam is parallel to it This can give a false appearance of

ultra-an ASD

The type of ASD can be determined by defi ning its tion PFO and secundum ASDs are located in the region of fossa ovalis, that is, the midatrial septal region (Fig 28.8)

loca-A PFO is guarded by a fl ap valve on the left side and limbus

of fossa ovalis to the right A PFO can be differentiated from

a secundum ASD by this overlap of septal tissue Ostium primum ASDs are located between the anteroinferior margin

of the fossa ovalis and AV valves Sinus venosus defects are seen superiorly at the junction of SVC with the right atrium (Fig 28.9) These defects are best seen from the subcostal short-axis or high right parasternal views as a communica-tion between the atria where the right upper pulmonary vein and SVC are usually seen The right pulmonary artery is seen

in cross-section immediately above the ASD Subcostal axis and parasternal short-axis views are useful in evaluating sinus venosus ASDs of the right atrial type which appear

long-as a posteroinferior atrial defect with a defi cient posterior margin (Fig 28.9) Anomalous drainage of right middle and lower pulmonary vein can be seen best in the parasternal short-axis view For CS defects, a large ostium of the CS is seen as an inferior interatrial communication, just above and anterior to the entry of IVC into the right atrium Absence

of the CS indicates complete unroofi ng In partial unroofi ng, parts of the wall between the CS and the left atrium can be identifi ed

The enlarged right atrium, right ventricle, and pulmonary arteries also are seen on 2-D imaging The volume-overloaded right ventricle causes diastolic fl attening and paradoxical motion of the interventricular septum (Fig 28.10) Associated anomalies such as pulmonary stenosis, mitral valve prolapse, and anomalous pulmonary venous return also should be eval-uated using 2-D imaging M-mode imaging of the ventricles will show an enlarged right ventricle and paradoxical septal motion (Fig 28.10)

D OPPLER

Using color Doppler, one can visualize the shunt across the ASD (Fig 28.8) This shunt usually is left-to-right, but in patients with elevated pulmonary artery pressure, a bidirec-tional shunt or a right-to-left shunt can be seen Pulsed-wave Doppler shows interatrial shunting in late systole and early diastole Since the pressure gradient across the atrial septum

is minimal when these defects are nonrestrictive, low- velocity

fl ow is noted using Doppler Commonly, a qualitative

Figure 28.7. Chest x-ray of a 5-year-old patient with a sinus

venosus ASD The x-ray shows cardiomegaly with right atrial

prominence, increased pulmonary vascular markings, and

prominent main pulmonary artery

assessment of the shunt across the ASD is done by direct

visualization of the shunt using color Doppler and its effect

on the right-sided cardiac chambers However, a

quantita-tive assessment of the pulmonary to systemic blood fl ow ratio

(Qp:Qs) also can be made For this, the time velocity integrals

obtained by tracing the pulsed-wave Doppler of pulmonary

and aortic outfl ow are multiplied by the area of pulmonary

and aortic valve, respectively This has been shown to have

a close correlation with the Qp:Qs measured invasively by

oximetry during cardiac catheterization (32) Presence of

right ventricular outfl ow tract obstruction, semilunar valve

insuffi ciency, and patent ductus arteriosus limit the use of this

method (33)

A large left-to-right shunt may result in a fl ow-related

peak gradient of as much as 30 mmHg across the pulmonary

valve However, with higher gradients, one must suspect

associated pulmonary valvular stenosis Progressive

tricus-pid regurgitation resulting from tricustricus-pid annular dilation

and lack of coaptation of leafl ets can be seen with signifi cant

right ventricular dilation Doppler assessment for estimating

pulmonary artery pressure can be performed by measuring

the tricuspid and pulmonary regurgitant jets and applying

the modifi ed Bernoulli equation to calculate transvalve

gra-dients and adding estimated right atrial pressure and right

ventricular end-diastolic pressure, respectively Development

of pulmonary hypertension results in worsening of

tricus-pid and pulmonary regurgitation In addition, the main

and proximal pulmonary arteries further dilate The right

ventricle becomes hypertrophied, and its systolic function starts deteriorating

C ONTRAST E CHOCARDIOGRAPHY

Intravenous contrast using injection of agitated saline during transthoracic or transesophageal echocardiographic imaging can be used to confi rm the shunting across an ASD or PFO A left-to-right shunt is seen as a negative contrast washout into the right atrium, when the right atrium is opacifi ed with contrast A right-to-left shunt is detected by the presence of microbubbles in the left atrium and ventricle, and this effect can be augmented by performing a simultaneous Valsalva maneuver In the presence of

an unroofed CS, injection of contrast in the left arm will result in microbubbles in the left atrium before it opacifi es the right atrium

Figure 28.8. Echocardiography delineation of defects in the region of fossa ovalis A: Subcostal sagittal view

showing a PFO (arrow), with a flap valve noted on the left atrial side and the limbus of fossa ovalis on the right

atrial side B: Subcostal coronal view showing a large secundum ASD with well-defined rims C: Color Doppler showing a left-to-right shunt across the ASD D: A pulsed-wave Doppler showing a left-to-right shunt across the

ASD with phasic changes LA, left atrium; RA, right atrium

Figure 28.9. Echocardiography of sinus venosus defects: A: Subcostal sagittal view showing the SVC-type sinus

venosus defect The defect (asterisk) is cranial to the superior limbic band of fossa ovalis and is in communication

with the cardiac end of SVC B: Color Doppler image of the same defect shows the blood directed from LA to

RA via the left atrial orifice of the right upper pulmonary vein and the sinus venosus defect C: Subcostal coronal

view showing the SVC-type sinus venosus defect (asterisk), the superior limbic band of fossa ovalis (arrow), and

orifice of the right upper pulmonary vein (RUPV) D: Subcostal coronal views of right atrial type of sinus venosus

defect (asterisk) showing a large defect in the posterior right atrial wall IVC, inferior vena cava; LA, left atrium;

RA, right atrium; RPA, right pulmonary artery

T HREE -D IMENSIONAL E CHOCARDIOGRAPHY

Imaging the ASD using 2-D echocardiography is based on

limited number of orthogonal planes and could result in

underestimation of the size of the ASD and its surrounding

rims With the availability of real-time 3-D echocardiography,

an en face view of the entire atrial septum can be obtained,

thus allowing better morphologic delineation of the ASD and

its surrounding structures (34) This information is helpful in

determining whether or not closure of the ASD can be

accom-plished with a transcatheter device (35) Furthermore, 3-D

transesophageal echo now is being used not only to delineate

anatomic features of ASD but also for guiding device closure

during the procedure (Fig 28.12) (36–38)

I NTRACARDIAC E CHOCARDIOGRAPHY

Intracardiac echocardiography using an ultrasound catheter has

been shown to be a safe alternative to transesophageal

echocar-diography for assisting in device closure of ASDs (39–42) It

provides excellent 2-D and color-Doppler imaging of the

intera-trial septum and the surrounding structures This technique has

the advantage of eliminating the need for general anesthesia

and additional personnel to perform transesophageal diography However, due to the large size of the sheath required

echocar-to insert the catheter, its use in smaller children is limited (42)

Cardiac Catheterization

In the current era cardiac catheterization seldom is indicated for diagnosis of ASDs unless pulmonary vascular disease is sus-pected Angiography can be helpful in diagnosing associated lesions such as partial anomalous pulmonary venous return

or mitral stenosis During catheterization, a step-up in oxygen saturations in the right atrium will be noted in the presence of

an atrial level left-to-right shunt An increase in saturations

of 10% or more from SVC and IVC in a single blood sample series or an increase of 5% in two series indicates the presence

of an atrial level shunt Similar results also can be obtained in the presence of a left ventricle to right atrial shunt, a ventricu-lar septal defect-related tricuspid insuffi ciency, AVSDs, sys-temic arteriovenous fi stula, or anomalous pulmonary venous return to the right atrium Detection of a CS type of ASD can be challenging Continuous oximetry using a fi beroptic

Figure 28.10. Severe right atrial (RA) and right ventricular (RV) dilation seen in a patient with large secundum

ASD: A: apical view; B: Parasternal long-axis view; C: Short-axis view D: M mode showing RV dilation and

paradoxical motion of the interventricular septum

catheter pull-back in the CS has been employed to diagnosis a

left-to-right shunting across such ASDs (43)

Qp:Qs can be calculated using the standard Fick equation or

indicator dilution technique In the absence of any other major

cardiac anomalies, the presence of a small left-to-right shunt

(Qp:Qs < 1.5) is considered hemodynamically insignifi cant

When the Qp:Qs is ≥1.5, the shunt is considered signifi cant

Direct measurement of intracardiac and pulmonary artery

pressure can be performed during catheterization, and

pulmo-nary vascular resistance can be calculated In the presence of

a large defect, there is minimal gradient between the two atria

and there can be a fl ow-related gradient across the pulmonary

valve as high as 30 mm Hg In cases of pulmonary

hyperten-sion, acute response to pulmonary vasodilators such as nitric

oxide and oxygen generally has been used to assess the

revers-ibility and make decisions regarding closure

Angiography just outside the orifi ce of right upper

pulmo-nary vein in a cranially angulated left anterior oblique

projec-tion is ideal for optimal visualizaprojec-tion of locaprojec-tion of the ASD (44) Injection into the main pulmonary artery will demonstrate pulmonary venous anatomy and shunt across the atrial septum, but is not ideal for determining the size and location of the ASD

A CS type of ASD can be diagnosed by injecting contrast tively into the left SVC, pulmonary vein, or left atrium (45)

selec-Other Imaging Modalities: CT/MRI

If the fi ndings on echocardiography are uncertain, ized tomography (CT) or magnetic resonance imaging (MRI) can be used to defi ne the anatomy of an ASD and its infl uence

computer-on the right-sided cardiac chambers and associated lies (Fig 28.13) (46,47) Both CT and MRI also have been used to defi ne the CS type of ASD, which can be particularly challenging to recognize using routine echocardiography (48)

anoma-Multislice CT has a high spatial and temporal resolution and

atrial septal defect (arrow) LA, left atrium; RA, right atrium; RV, right ventricle.

Superior

Inferior

Aorta

Tricuspid valve Coronary

superior

inferior

Direction of left ventricular apex Aorta

B

Left atrial surface

anterior posterior

0 80 180

B: Left atrial view of secundum ASD IVC, inferior vena cava; SVC, superior vena cava (From Pushparajah K,

Miller OI, Simpson JM 3D echocardiography of the atrial septum: anatomical features and landmarks for the

echocardiographer JACC Cardiovasc Imaging 2010;3:981–984, with permission).

multiplanar reconstruction capabilities to characterize ASDs

and pulmonary venous anomalies, though at the cost of

radia-tion exposure (49) MRI is being used increasingly in adults

since the transthoracic echocardiographic images can be quite

limited MRI has been shown to have a good correlation with

TEE in assessing the size and rims of the defect (47)

Velocity-encoded, phase-difference MRI measurements of fl ow in the

proximal great vessels has been used to noninvasively measure

Qp:Qs with results comparable to those obtained by oximetry

and indicator dilution techniques (50)

Exercise Testing

Even though most patients with ASD are asymptomatic, their

exercise capacity may be decreased Closure of an ASD may

improve exercise capacity in adults who were asymptomatic

or mildly symptomatic prior to closure (51) Exercise capacity

is uniformly low in patients with ASD and pulmonary

hyper-tension In cases where the symptoms are discordant with the

clinical fi ndings, it can be useful to document the exercise

capacity Exercise testing can be helpful in documenting

oxy-gen saturations during exertion in patients with pulmonary

hypertension, though maximal exercise is not recommended in

the presence of severe pulmonary hypertension (52)

Natural History of ASDs

While secundum ASDs can spontaneously close over time,

other types of ASDs do not In a report on the natural

his-tory of unrepaired ASD, Campbell (53) noted that the

mean age of death was 37.5 ± 4.5 years with 75% dying by

50 years and 90% dying by 60 years of age This was in

the era prior to echocardiography where reports regarding

outcome of ASDs obviously were skewed toward clinically

recognizable defects Since the advent of echocardiography,

it is possible to report data from serial echocardiographic

evaluations estimating the change in the size of the defect

and the rate of spontaneous closure (54–56) In general, most

defects <5 mm that were recognized during infancy are likely

to spontaneously close, while those larger than 8 to 10 mm are unlikely to do so

In a report of 30 children with secundum ASDs (mean age

at diagnosis 1.3 years) that were considered hemodynamically insignifi cant during infancy, Brassard et al (57) noted that

17 children had spontaneous closure of the defect at a mean age

of 8.4 years In seven asymptomatic patients, the defect size was

1 to 6 mm at a mean follow-up of 13.2 years In the ing six patients, the defect had become larger and closure was performed since the patients were symptomatic or the defect was determined to be hemodynamically signifi cant (57) Radzik

remain-et al (58) evaluated the predictive factors for spontaneous sure of ASDs diagnosed in infants <3 months They reported that the frequency and timing of closure were inversely related to the diameter of the ASD At a mean follow-up of about 14 months, spontaneous closure occurred in all the defects that were <3 mm

clo-at diagnosis, in 87% of defects thclo-at were 3 to 5 mm, in 80%

of defects that were 5 to 8 mm, and in none of the defects that were ≥8 mm In a longitudinal study of 200 children with iso-lated secundum ASDs diagnosed at a median age of 5 months, Hanslik et al (59) reported spontaneous closure in 34% and

a decrease in size to ≤3 mm in another 28% ASD diameter and age at diagnosis were noted to be independent predictors

of spontaneous closure or regression to ≤3mm defect size None

of the ASDs >10 mm at diagnosis closed spontaneously (59)

In contrast to the above studies, a study by McMahon et al

(60) of 104 patients with isolated secundum ASDs reported that the diameter of ASDs increased in 65% of their cohort, with

a >50% increase in 30% of their patients Spontaneous sure occurred in only 4%, and 12% reached a size of ≥20 mm

clo-The mean age at diagnosis in this study was much older (4.5 years, range 0.1 to 71 years) than in the previously mentioned studies, and the mean interval between echocardiograms was 3.1 years (0.7 to 8.1 years), which may contribute to the differ-ences reported in the natural history of secundum ASDs (60)

Pulmonary vascular obstructive disease may develop in patients with large left-to-right shunts during adulthood, though it occurs much later with ASDs compared to high-pressure left-to-right shunts such as ventricular septal defects

or patent ductus arteriosus According to Craig and Selzer (3), young adults with ASD have about a 14% chance of devel-oping progressive pulmonary hypertension Eventually, when there is reversal of the left-to-right shunt, these patients become progressively cyanotic and symptomatic They eventually die

of cardiac failure or pulmonary artery thrombosis (3) Their pulmonary vascular disease usually is progressive and becomes irreversible Acute response to vasodilators during cardiac catheterization is helpful to determine reversibility, though some cases may still fall into an indeterminate zone where it

is diffi cult to differentiate between a reversible and an ible state In patients with advanced pulmonary vascular dis-ease, closure of the ASD can result in further deterioration of the patient and decreased survival compared to patients with unrepaired ASDs (61) In most of these patients there is right ventricular failure, and the right-to-left shunt across the ASD provides increased cardiac output albeit at the cost of cyanosis

irrevers-Chronic volume overload, elevated pulmonary artery sures, ventricular dysfunction, and AV valve regurgitation can contribute to atrial stretching, which in turn predisposes to atrial arrhythmias Late in the natural history of ASDs, atrial arrhythmias in the form of atrial fi brillation, fl utter, or less commonly, paroxysmal supraventricular tachycardia contrib-ute to morbidity and mortality

pres-Management

Most children with an ASD are asymptomatic In rare cases when they are symptomatic, anticongestive therapy with diu-retics may be indicated until closure is accomplished Closure

angiogram showing anomalous drainage of right upper and

middle pulmonary veins (arrows) into the SVC B: Bright blood

image in axial plane showing drainage of right upper

pulmo-nary vein (asterisk) to the SVC C: Bright blood image showing

a sinus venosus defect (asterisk) AA, ascending aorta; LA, left

atrium; RA, right atrium; RPA, right pulmonary artery

of an ASD is indicated if there is a large shunt, that is, Qp:Qs

≥1.5 Other indicators of a large shunt include a diastolic

fl ow rumble in the tricuspid area, ECG evidence of right

ven-tricular hypertrophy, chest x-ray evidence of cardiomegaly or

increased pulmonary vascular markings, or echocardiographic

evidence of right ventricular enlargement and/or

paradoxi-cal septal motion (62) In asymptomatic patients with a large

shunt, elective closure between 2 and 5 years of age is

recom-mended (62) Even though most children with large defects

may be asymptomatic, elective closure is recommended to

prevent long-term complications such as atrial arrhythmias,

paradoxical embolism, pulmonary hypertension, severe right

ventricular dilation and dysfunction with overt symptoms

of congestive heart failure, and hemodynamically signifi cant

mitral and tricuspid insuffi ciency If large ASDs are identifi ed

later in life, it is important to have evidence of pulmonary

vascular reactivity and a net left-to-right shunt prior to

con-sidering closure Those with irreversible pulmonary

hyperten-sion are not candidates for ASD closure and warrant medical

therapy for treatment of pulmonary hypertension

Closure of small defects without any right-sided

car-diac enlargement is controversial While these patients may

remain asymptomatic well into their fourth and fi fth decades

of life, there is concern about increase of the left-to-right

shunt at an older age due to reduced left ventricular

compli-ance as a result of CAD, systemic hypertension, or

valvu-lar disease (52) Routine follow-up of these patients during

adulthood should include assessment for atrial arrhythmias

and paradoxical embolic events and an echocardiogram

every 2 to 3 years to evaluate right atrial and ventricular size

and pressures (52)

Although closure of secundum ASDs can be performed with

percutaneous devices or surgically, surgical closure is the only

option for sinus venosus, CS, and primum ASDs ASDs with

multiple fenestrations and atrial septal aneurysm (ASA) require

careful evaluation before proceeding with device closure

Secundum ASDs

Surgical Closure: Surgical closure of an ASD was fi rst

per-formed by Murray in 1948 using an external suture technique

without directly visualizing the defect With development of

the pump oxygenator, in 1953 Gibbon performed closure of

ASD using the open technique that allowed complete

visu-alization of the defect For small to moderate ASDs direct

suture closure can be accomplished If the ASD is too large

to allow direct suture closure, patch closure is performed Use

of autologous pericardial patch has eliminated the need to

use prosthetic material, thereby theoretically, minimizing the

risks of thromboembolism and endocarditis In adult patients

with atrial arrhythmias, a concomitant Maze procedure can be

performed Conventionally, median sternotomy approach has

been used for surgical repair of ASD More recently, partial

lower sternotomy has been used particularly in children below

3 years of age (63,64)

Surgical mortality and morbidity for secundum ASDs with normal pulmonary vascular resistance are negligible The majority of patients who had closure of secundum ASDs dur-ing childhood have had an uncomplicated course with a nor-mal cardiac rhythm and exercise capacity Rarely, there may

be inadvertent attachment of the eustachian valve to the atrial septum, thereby diverting blood from inferior vena cava to the left atrium and causing a right-to-left shunt, necessitating surgical reintervention

The long-term outcome following surgical repair of ASD primarily depends on the age at surgery and pulmonary artery pressures prior to surgery Several investigators have reported the outcome in patients with pulmonary hyperten-sion who have undergone surgical closure of ASD In 1960, Rahimtoola et al (65) reported that the outcome in those who had a peak pulmonary artery pressure of more than 60

mm Hg is poor In 1973, Dave et al (66) reported that cal outcome is adversely affected when the mean pulmonary artery pressure was more than 40 mm Hg In 1987, Steele et

surgi-al (25) reported that in patients with pulmonary hypertension, total pulmonary resistance, pulmonary arteriolar resistance, pulmonary-to-systemic resistance ratio, and systemic and pulmonary arterial oxygen saturation were all predictors of surgical outcome, with total pulmonary resistance being the best one In 1990, Murphy et al reported the long-term post-operative outcomes of 123 patients at Mayo Clinic between

1956 and 1960 who had surgical repair of secundum or sinus venosus ASDs The overall 30-year actuarial survival rate among survivors of the perioperative period was 74%, compared to 85% among age- and sex-matched controls (67) The late survival in patients undergoing surgery below

24 years of age was similar to that of the control population

However, survival is signifi cantly decreased in those repaired between 25 and 41 years when compared to the controls (84%

and 91%, respectively) There was a further decline in late survival in those repaired after 41 years of age to 40% versus 59% in controls (67) Independent predictors for long-term survival were younger ages at operation and lower preopera-tive pulmonary artery systolic pressures (67) Late repair was associated with signifi cant morbidity including atrial fi brilla-tion, stroke, and cardiac failure

Device Closure

Transcatheter device closure of secundum ASDs has signifi cantly altered the management of ASDs The fi rst transcatheter device closure was reported by King et al (68) in 1976 Fol-lowing that, several modifi cations in devices as well as delivery systems have been made Various devices such as Amplatzer septal occluder, CardioSEAL, Gore HELEX septal occluder,

-Figure 28.14. Various devices used for transcatheter closure of ASD A: Amplatzer septal occluder (Illustration courtesy of AGA Medical Corp.) B: Gore Helix septal occluder (Illustration courtesy of W.L Gore & Associ- ates, Inc) C: CardioSEAL device D: BioSTAR device (Illustrations C and D courtesy of NMT Medical, Inc.)

Clamshell occluder, Sideris Buttoned device, Das-Angel Wings

occlusion device, and BioSTAR are now available (Fig 28.14)

The Amplatzer septal occluder is currently the most widely

used device Some of the advantages of this device include

relatively easy deployment, easy retrievability (until released

from the delivery system), ability to close large defects, and

the relatively larger left atrial disc to close additional atrial

fenestrations

While device closure has proven to be technically safe and

feasible and has the obvious advantage of being a nonsurgical

technique, it is not free of complications These complications

include fracture or embolization of the device, device

malalign-ment, residual shunts, device thrombosis, and impingement of

adjacent structures such as valves, SVC, CS, pulmonary veins,

or aorta (69–71) Also, long-term problems such as late

ero-sion of the atrial wall or aorta, inaccessibility of the left atrium

if needed, and artifact during MRI can be encountered (72)

A partially biodegradable device (BioSTAR) made of collagen

discs and metallic arm and rings has been developed to

over-come some of these problems This device has been used in

Europe since 2006 for PFO and ASD closure (73) The closure

rates are comparable to the Amplatzer device with very little

foreign material left over at 6 months’ follow-up (74) A fully

absorbable transcatheter device (BioTREK) is currently

under-going experimental trials

In the current era of ASD device closure, several studies

have evaluated outcomes of ASD closure using this technique

in patients with pulmonary hypertension In 2008, Balint et al

(75) reported the outcome of device closure of ASD with

mod-erate or severe pulmonary arterial hypertension They noted

that at a mean follow-up of 31 months, although there was

a decrease in the mean right ventricular systolic pressures as

determined by echocardiography, it normalized in only 44%,

while 15% had persistence of severe pulmonary hypertension

In 2009, Yong et al (76) reported a longitudinal study

evalu-ating pulmonary hypertension in 215 adults with attempted

device closure of ASDs Independent predictors of moderate

or severe pulmonary hypertension were older age, larger ASD,

female sex, and presence of at least moderate tricuspid

regur-gitation (76) Among patients with moderate or severe

pulmo-nary hypertension, independent predictors of normalization

of pulmonary pressure were lower baseline pulmonary artery

pressure and no more than mild tricuspid regurgitation (76)

In a study of 236 adults who had device closure of ASD at a

mean age of 49 ± 18 years, Humenberger et al (77) found

that ASD closure at any age was followed by improvement

in symptoms and decrease in pulmonary artery pressures and

right ventricular size, but the best outcome was in patients

with less functional impairment and lower baseline pulmonary

artery pressures These studies indicate that, similar to

surgi-cal closure of ASDs, the outcome following device closure is

infl uenced by age at closure and the presence of pulmonary

hypertension

Sinus Venosus ASD

In the rare case where the sinus venosus ASD is not associated

with anomalous pulmonary venous return, an autologous

pericardial patch closure of the ASD is performed However,

in more than 90% of cases, anomalous pulmonary venous

return to the SVC is present In such cases, surgical

correc-tion involves closure of ASD and redireccorrec-tion of anomalous

pulmonary veins into the left atrium While the surgery for

superior, posterior, and inferior sinus venous ASD with

anom-alous veins draining directly into the right atrium is associated

with minimal complications, that for anomalous pulmonary

veins connected to SVC is complex and can be associated with

long-term complications such as obstruction of the

pulmo-nary vein orifi ce, SVC stenosis, sinus node dysfunction, and

atrial arrhythmias, including atrial fl utter or atrial fi brillation depending on the surgical technique used In the intracaval baffl e technique the anomalous pulmonary venous return

is redirected through the sinus venosus defect by baffl ing these structures with a pericardial or synthetic patch with or without performing a patch cavoplasty as needed (78) The transcaval technique uses a lateral incision in the SVC and a single-patch closure of the ASD along with baffl ing of anoma-lous pulmonary veins into the left atrium (79) When the right pulmonary venous insertion into the SVC is high (more than

2 cm above the atriocaval junction), the Warden procedure

is used, in which the SVC is transected above the site of the anomalous pulmonary veins and connected to the right atrial appendage The cardiac end of the SVC along with the anom-alous pulmonary venous fl ow is baffl ed into the left atrium with a patch (80)

Coronary Sinus ASD

In a partially unroofed CS defect, repair can be performed using a roofi ng procedure (81) If there is redundant tissue, primary closure of the defect can be performed If that is not feasible, a roof can be created using a pericardial patch

Most cases of CS ASD are associated with a left SVC which

is dealt with on its own merits If the left SVC is small and there is a bridging vein, it can be ligated If it is large and is the only source of systemic venous drainage from the head and upper extremities, an intraatrial baffl e can be performed

Management Issues During Follow-Up

Patients who had surgical closure of ASD during childhood have an excellent outcome In general, they have decrease in or resolution of preoperative symptoms, an increase in exercise capacity, and are free of signifi cant cardiac rhythm abnormali-ties However, the outcome in those who had surgery during adulthood is signifi cantly different due to pulmonary hyper-tension, atrial arrhythmias, and cardiac failure Device closure

is also associated with early and long-term complications as mentioned above which warrant long-term surveillance Spe-cifi c issues that need attention during follow-up are discussed below

Postpericardiotomy Syndrome

During the fi rst few weeks postoperatively, patients may present with fever, chest pain, abdominal pain, emesis, and fatigue These symptoms should alert one to the diagnosis of postpericardiotomy syndrome, and an echocardiogram should

be performed to exclude pericardial effusion and cardiac ponade

tam-Pulmonary Hypertension

It is well established that the outcome of patients with repaired

or unrepaired ASD and pulmonary hypertension is not ble compared to those with normal pulmonary artery pressure

favora-Despite closure of the defect, pulmonary vascular disease may progress in some patients Therefore, periodic surveillance along with serial Doppler echocardiograms is recommended

to estimate pulmonary artery pressures Medical therapy using pulmonary vasodilators should be instituted if indicated

with atrial arrhythmias also are more likely to have higher

pulmonary artery pressures and worse functional class (83)

Patients older than 40 years at the time of ASD closure are

more likely to have new-onset atrial arrhythmias Those with

atrial arrhythmias before and soon after ASD closure are more

likely to have persistent arrhythmias (83) In patients

predis-posed to atrial arrhythmias, periodic follow-up with ECG and

Holter monitoring is recommended Atrial arrhythmias should

be appropriately treated to restore and maintain sinus rhythm

If sinus rhythm cannot be restored with medical or

interven-tional means, then rate control and anticoagulation are

recom-mended (52)

Right Atrial and Ventricular Size and Function

Following ASD closure, there is regression of right atrial and

ventricular size in the majority of patients, irrespective of the

technique used for closure (46,84) Most of the regression

occurs within the fi rst year following closure (85) While

sig-nifi cant changes in the right atrial size may not be observed

acutely, that too decreases over time (86) Regression in

right heart size is less in patients repaired at an older age

and in those with pulmonary hypertension Right

ventricu-lar systolic function is normal to hyperdynamic in those with

unrepaired ASDs, but chronic volume overload can result in

reduced right ventricular systolic and diastolic dysfunction in

adults, which may or may not improve following closure of

the defect

Left Ventricular Function

Although earlier reports indicated that left ventricular

func-tion was normal in patients with ASD, there is now evidence

that both systolic and diastolic function can be infl uenced

adversely by severe chronic right ventricular volume overload

(87–89) Therefore, monitoring of both right and left

ventricu-lar function during follow-up is advisable

Mitral Regurgitation

Patients with ASD may develop mitral valve prolapse and

insuffi ciency, presumably from leftward shifting of the

ventric-ular septum due to an enlarged right ventricle (90) This may

persist after successful closure of the defect (90,91) While the

etiology of mitral regurgitation has been ascribed to

mechani-cal ventricular dysfunction, the valve itself often is noted to

be morphologically abnormal with myxomatous changes and

prolapse (92)

Bacterial Endocarditis

Patients with isolated ASDs are not predisposed to endocarditis

unless there is an associated valvular lesion such as cleft mitral

valve with mitral valve regurgitation There are rare reports

of bacterial endocarditis following uncomplicated surgical or

device closure of ASD Endothelialization of prosthetic

mate-rial or devices usually occurs within the fi rst 6 months after the

procedure Therefore, antibiotic prophylaxis is recommended

for the fi rst 6 months following such a procedure and is then

discontinued (93)

ASD in Adults

ASD is the most common congenital heart disease in adults

accounting for up to 30% of congenital heart defects in this

age-group Patients with ASD may survive into adulthood

without being diagnosed Although many come to attention

due to abnormal physical fi ndings, chest x-ray, or ECG, some

may present with a cerebrovascular event due to paradoxical

embolism or signs and symptoms related to cardiac failure,

arrhythmias, or pulmonary hypertension Dyspnea on tion is the most prevailing symptom present in symptomatic adults with ASD Other symptoms include fatigue, palpita-tions, and rarely, chest pain (3) The development of these symptoms can be attributed to multiple factors In older patients, left ventricular compliance may be reduced due to systemic hypertension or CAD, which in turn increases the left-to-right shunt across the ASD Chronic right ventricular volume overload ultimately results in right ventricular fail-ure and progressive tricuspid valve insuffi ciency Survival into adulthood is quite common with infrequent deaths during the fi rst two decades of life Symptoms of progressive pulmo-nary hypertension can begin in the third decade The mortal-ity rate is signifi cant after the fourth decade, around 6% per year (53)

exer-Adults who had surgical repair of secundum ASDs during childhood are usually symptom free, but rarely can have atrial arrhythmias and sick sinus syndrome (94) When surgery is performed in adults, the outcome primarily depends on the age at repair and the pulmonary artery pressures Konstan-tinides et al (95) compared outcomes of 179 patients ≥40 years with secundum ASD who were treated either medically

or surgically The 10-year survival in the medically managed group was 84% compared to 95% in surgically managed group The functional status of one-third of the medically managed patients deteriorated, but improved in those who had surgical repair, though the incidence of atrial arrhythmias

and cerebrovascular events was similar in both groups (95)

Horvath et al (96) reported early and long-term follow-up

of surgical repair of secundum and sinus venosus ASDs in

166 adults repaired at Brigham and Women’s Hospital at a mean age of 44 years The 5- and 10-year survival rates were 98% and 94%, respectively There were two operative deaths and six late deaths Those with a systolic pulmonary artery pressure of >30 mm Hg had signifi cantly higher late mortal-ity St John Sutton et al (97) reported patients who had sur-gical closure of ASD between 60 and 78 years There was improved survival in patients discharged from the hospital following surgery compared to age- and sex-matched medi-cally treated controls In this study, the majority of patients showed symptomatic improvement irrespective of preopera-tive pulmonary vascular resistance and functional class (97)

Based on these studies and several others in the literature, there is general agreement that symptomatic adult patients improve after closure of ASD; the only contraindication for closure is severe pulmonary hypertension There is some con-troversy over management of asymptomatic adults, but clo-sure can be performed with minimal risk with the advantage

of reducing overload of right ventricle and progression of cuspid insuffi ciency and in many cases reducing progression

tri-of pulmonary hypertension Moreover, there is improvement

in functional capacity even in asymptomatic patients ing ASD closure (51) Given the low mortality and morbidity associated with closure of ASD within the fi rst two decades of life, these patients have no cardiac restrictions and can have less frequent follow-up provided there is no cardiac rhythm

follow-or hemodynamic concerns Patients repaired in their third decade and beyond require regular surveillance for atrial arrhythmias, cardiac failure, stroke, and pulmonary vascular disease(52,98)

In general, pregnancy in patients with ASD is well tolerated

as the increase in the left-to-right shunt across the atrial septum

is balanced by the decrease in peripheral vascular resistance

Paradoxical embolism may occasionally occur unrelated to the size of the ASD Pregnancy is not recommended in patients with ASD and severe pulmonary artery hypertension due to very high maternal and fetal mortalities (52) Such patients may develop arrhythmias, ventricular dysfunction, and pro-gressive pulmonary hypertension during pregnancy

Atrial Septal Aneurysm

An ASA is a saccular deformity of the atrial septum with a

reported prevalence of 0.22% to 1.9% (99,100) Although

in most cases the aneurysm is limited to the region of the

fossa ovalis, it occasionally can involve the entire septum

(Fig 28.15D) ASA may protrude into the left or the right

atrium or have a bidirectional excursion Various classifi

ca-tions of ASA based upon its excursion have been proposed

(99,100) Hanley et al (99) suggested diagnostic criteria for

ASA based on transthoracic echocardiograms that include

(a) protrusion of the aneurysm at least 15 mm beyond the

plane of the atrial septum or when the atrial septum shows

a phasic excursion of ≥15 mm during the cardiorespiratory

cycle and (b) the base amplitude (width) of the aneurysm

≥15 mm Although ASAs may occur in isolation, they

com-monly are associated with congenital or acquired heart

dis-ease The most commonly associated cardiac lesion is ASD,

though other lesions such as ventricular septal defects,

pul-monary stenosis, patient ductus arteriosus, coarctation, and

interrupted aortic arch can occur (101) ASAs also have been

associated with atrial arrhythmias, AV valve prolapse, and

sys-temic and pulmonary embolism (99) The association of ASA

with cerebrovascular events, in particular cryptogenic strokes

has been reported The coexistence of a PFO with an ASA

further increases the risk of stroke The potential source of

embolization in these cases could be a primary thrombus in

the aneurysm or paradoxic embolization through interatrial

shunting (102,103) TEE provides superior images for phologic characterization of ASA It also is helpful in defi ning interatrial shunting and the presence of multiple fenestrations and thrombi within the aneurysm (102,104)

mor-Management of patients with ASA and stroke includes medical therapy with aspirin or warfarin or closure by surgi-cal or transcatheter technique (105)

Patent Foramen Ovale

A PFO is a normal interatrial communication present in fetal life that persists in many adults (Fig 28.15) Based on transesophageal echocardiography, it is present in up to 24%

of healthy adults (106) A Mayo Clinic study based on 965 autopsy specimens of human hearts reported the incidence and size of the PFO during the fi rst 10 decades of life (107) While the overall incidence was 27.3%, it progressively declined with increasing age from 34.3% during the fi rst three decades of life

to 25.4% during the fourth through eighth decades and to 20.2% during the 9th and 10th decades (107) Furthermore, the PFO size increased from a mean of 3.4 mm in the fi rst decade to a mean of 5.8 mm in the 10th decade, likely due to stretching of the fossa ovalis over time The incidence and size

of PFO were reported to be similar in males and females (107)

In the current era, transcatheter closure of PFOs is formed using a wide variety of devices such as Amplatzer, CardioSEAL-STARfl ex, Helex occluder, and BioSTAR, a new

C

D

Figure 28.15. Patent foramen ovale A: Right atrial view B: Left atrial view A white probe is seen between the

limbus and valve (V) of the fossa ovalis and enters the left atrium (LA) through the ostium secundum (white

arrow) C: Right atrial view Atrial dilation has resulted in a valvular-incompetent PFO, that is, an acquired ASD

(asterisk) D: Atrial septal aneurysm Four-chamber view showing aneurysm of the fossa ovalis (arrows) bulging

toward the right LAA, left atrial appendage; VS, ventricular septum (See Fig 28.2 for other abbreviations.)

bioabsorbable implant (108,109) While the safety and effi

-cacy of these devices has been reported in many studies,

com-plications are similar to those with the devices used for ASD

closure and include device embolization, hemopericardium,

device thrombosis, residual shunts, and paroxysmal atrial

fi brillation (108)

PFO has been associated with cryptogenic strokes,

tran-sient ischemic attacks, and migraine headaches (110)

Sys-temic, noncerebral paradoxical embolism also rarely can

occur in the form of myocardial infarction, renal infarction,

or limb ischemia (111) The prevalence of PFO has been noted

to be higher in patients with cerebrovascular events than in

those without cerebral vascular events ranging from 40% to

70% Therefore, a potential etiologic role has been suggested

These patients have been treated with antithrombotic drugs

like warfarin and aspirin, or closure has been performed to

prevent future events (105,112,113) The recurrence of these

events is not completely eliminated following surgical or

tran-scatheter closure of PFO (113) Similar to studies in patients

with stroke, some studies have reported relief of migraine with

aura following closure of PFO (114–116) However, a recent

population-based study of 1,100 stroke-free patients with

self-reported migraines did not fi nd any signifi cant associations

between PFO and migraine (117) Direct documentation of

paradoxical embolization through the PFO resulting in

cer-ebrovascular events obviously is challenging Hence, the role

of closure of PFO in such patients remains controversial In

the current era of device closure, there has been a dramatic

increase in the rate of PFO closure in these patients in light

of some observational studies reporting reduced incidence of

recurrence However, there are no randomized control trials as

yet to prove the benefi t of closing PFOs (105,118,119)

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691

29

Frank Cetta ■ L Luann Minich ■ Joseph J Maleszewski ■ Joseph A Dearani ■ Harold MacDonald Burkhart

Atrioventricular Septal Defects

INTRODUCTION AND NOMENCLATURE

Atrioventricular septal defects (AVSDs) are a group of

anomalies that share a defect of the atrioventricular (AV)

sep-tum and abnormalities of the AV valves The terms “AV canal

defects” or “endocardial cushion defects” also describe these

lesions but, for the purposes of this chapter, the term

atrioven-tricular septal defect is used These lesions are divided into

par-tial and complete forms In parpar-tial AVSD, a primum atrial septal

defect (ASD) always is present and there are two distinct, but

focally contiguous, right and left AV valve annuli The left AV

valve invariably is cleft The complete form also includes a

pri-mum ASD, but it is contiguous with an inlet ventricular septal

defect (VSD), and the common AV valve has a single annulus

Similarly, the clinical manifestations and management of these

patients depend on the extent and severity of the lesions present

Several classifi cations have been used to describe AVSDs

Transitional AVSD is a subtype of partial AVSD This term is

used when a partial AVSD also has a small inlet VSD that is

partially occluded by dense chordal attachments to the

ven-tricular septum Intermediate AVSD is a subtype of complete

AVSD that has distinct right and left AV valve orifi ces despite

having only one common annulus These separate orifi ces are

referred to as right and left AV valve orifi ces rather than

tri-cuspid and mitral This also is true when describing the valves

after repair of complete AVSD The VSD in intermediate AVSD

is large similar to other forms of complete AVSD

Unfortu-nately, the terms “transitional” and “intermediate” have been

confused and are used synonymously in the literature Because

of the confl icting and confusing terminology of these subtypes,

the clinician, echocardiographer, and surgeon should

com-municate by simply describing AV valve morphology, cardiac

chamber sizes, and magnitude of shunting observed

Com-plete and intermediate AVSDs have the physiology and clinical

features of a combined ASD and VSD, whereas partial and

transitional AVSDs have the clinical picture of a large ASD

(Fig 29.1) Anatomic features shared by all forms of AVSD are

summarized in Table 29.1

Surgical repair of AVSDs has been one of the great

suc-cesses of the last several decades of congenital cardiac surgery

Recently, the Pediatric Heart Network (PHN) reported AVSD

outcome data from seven North American centers

demon-strating an overall operative mortality of 3% (1,2) Long-term

survival has been excellent Cumulative 20-year survival of

95% has been reported (3) This success has been tempered

by the relatively large number of patients (~25%) who await

reoperation, most commonly because of progressive left AV

valve regurgitation or for relief of left ventricular outfl ow tract

(LVOT) obstruction Unfortunately, the prevalence of

postop-erative left AV valve regurgitation has remained the most

com-mon sequel of repair for decades The PHN study found that

26% of patients had more than moderate left AV regurgitation

6 months after “repair” (1,2)

on routine fetal four-chamber imaging Gender distribution is approximately equal or may show a slight female preponder-ance (4)

About 40% to 45% of children with Down syndrome have congenital heart disease, and among these, approximately 45% have an AVSD In more than 75% of patients with Down syndrome, it is the complete form of AVSD (7) Conversely, approximately 50% of patients with AVSD have Down syn-drome Race and ethnicity may factor into prevalence of AVSD

in patients with Down syndrome Patients of Black African ancestry with Down syndrome have AVSD more commonly than do whites Familial occurrence of AVSD is rare Com-plete AVSDs also occur in patients with heterotaxy syndromes (more common with asplenia than with polysplenia) Com-mon atrium has been associated with Ellis-van Creveld and heterotaxy syndromes (8–11)

EMBRYOGENESIS

The etiology of AVSDs has traditionally been considered as faulty development of the AV endocardial cushions However, recent studies have illustrated additional pathways involving the “dorsal mesenchymal protrusion” that may act alone or

in concert with development of the endocardial cushions to create AVSDs (12) In partial AVSDs, incomplete fusion of the superior and inferior endocardial cushions results in a cleft in the midportion of the left AV valve anterior leafl et often asso-ciated with regurgitation In contrast, complete AVSD is asso-ciated with lack of fusion between the superior and inferior cushions and, consequently, with the formation of separate anterior and posterior bridging leafl ets along the subjacent ventricular septum (Fig 29.2)

Failure of the endocardial cushions to fuse creates a defect

in the AV septum The primum atrial septal component of this defect usually is large This results in downward displacement

of the anterior left AV valve leafl et to the level of the septal right AV valve leafl et (13) In AVSDs, the AV valves have the same septal insertion level in contrast to the leafl et arrange-ment in the normal heart (Fig 29.3) The distance from the cardiac crux to the left ventricular apex is foreshortened, and the distance from the apex to the aortic valve is increased

This is in contrast to the normal heart, in which the two tances are roughly equal (Fig 29.4) In AVSDs, the dispropor-tion between the two distances causes anterior displacement of

dis-the LVOT resulting in elongation and narrowing of dis-the LVOT

producing the characteristic “gooseneck” deformity After

sur-gical repair of the defect, progressive subaortic stenosis still

may develop (14)

Since the dextrodorsal conus cushion contributes to the

development of the right AV valve and the outfl ow tracts lie

adjacent to their respective infl ow tracts, AVSDs may be

asso-ciated with conotruncal anomalies, such as tetralogy of Fallot

and double-outlet right ventricle (RV) In addition, shift of the

AV valve orifi ce may result in connection of the valve primarily

to only one ventricle, creating disproportionate or unbalanced

ventricles

PARTIAL ATRIOVENTRICULAR SEPTAL DEFECT

Pathology

In partial AVSD, the right and left AV valve annuli are separate

The most frequent form of partial AVSD consists of a primum

ASD and a cleft left AV valve anterior leafl et (Figs 29.5 and

29.6) Most primum ASDs are large and located anterior and

inferior to the fossa ovalis The defect is bordered by a

crescen-tic rim of atrial septal tissue posterosuperiorly and by AV valve

continuity anteroinferiorly These defects are not amenable to

transcatheter device closure because of their proximity to the

AV valves

The right and left AV valves have the same septal insertion level because the left AV valve annulus is displaced toward the ventricular apex As a result, the defi cient AV septum is associ-ated with an interatrial communication rather than an inter-ventricular or right atrial to left ventricular communication

Nonetheless, the defect imparts a scooped-out appearance to the inlet ventricular septum, and the distance from the left AV valve annulus to the left ventricular apex is less than the dis-tance from the aortic annulus to the apex (Fig 29.4)

The cleft in the left AV valve anterior leafl et is directed toward the midportion of the ventricular septum, along the anteroinferior rim of the septal defect (Fig 29.7) In contrast, isolated mitral valve clefts (not associated with AVSD) are directed toward the aortic valve annulus (15) The left AV valve orifi ce is triangular rather than elliptical (as in a normal heart) and resembles a mirror-image tricuspid valve orifi ce

The cleft left AV valve usually is regurgitant and, with time, becomes thickened and exhibits histologic alterations that resemble myxomatous mitral valve prolapse

The most common associated anomalies with partial AVSD are a secundum ASD, patent ductus arteriosus (PDA), and a persistent left superior vena cava connecting to the coronary sinus (1) Less frequently, pulmonary stenosis, tricuspid steno-sis or atresia, cor triatriatum, coarctation of the aorta, mem-branous VSD, pulmonary venous anomalies, and hypoplastic right or left ventricle (LV) have been reported (16–18)

Clinical Manifestations

Although patients with partial AVSD may be asymptomatic until adulthood, symptoms of excess pulmonary blood fl ow typically occur in childhood Tachypnea and poor weight gain occur most commonly when the defect is associated with moderate or severe left AV valve regurgitation or with other hemodynamically signifi cant cardiac anomalies Patients with primum ASDs usually have earlier and more severe symptoms, including growth failure, than patients with secundum ASDs

An uncomplicated primum ASD often is discovered in young children when echocardiography is performed to investigate a murmur The murmur has typical systolic ejection qualities and

is best heard over the upper left sternal border with radiation to the lung fi elds The murmur is caused by turbulent fl ow across the pulmonary valve (not fl ow through the ASD) The second heart sound is widely split and fi xed during respiration An S1-coincident

and physiologic similarities between the

dif-ferent forms of AVSD are illustrated

Com-plete AVSDs have one annulus with large

interatrial and interventricular

communica-tions Intermediate defects (one annulus, two

orifices) are a subtype of complete AVSD and

have a large ventricular septal defect (VSD)

Complete AVSDs have physiology of VSDs

and ASDs In contrast, partial AVSDs have

physiology of ASDs Transitional defects

are a form of partial AVSD in which a small

inlet VSD is present Partial AVSD and the

intermediate form of complete AVSD share

a similar anatomic feature: A tongue of

tis-sue divides the common atrioventricular valve

into distinct right and left orifices LA, left

atrium; LPV, left pulmonary vein; LV, left

ventricle; RA, right atrium; RPV, right

pul-monary vein; RV, right ventricle (With

per-mission of Patrick O’Leary, MD.)

■ AV valve leafl ets insert at the same level at the cardiac crux

■ Absence of the AV septum

■ Unwedged and anterior displacement of the aortic valve

■ Elongated LVOT

■ Counterclockwise rotation of the LV papillary muscles

■ Cleft left AV valve component, directed toward the

ventricular septum

29.1

Forms of AVSD

holosystolic murmur due to left AV valve regurgitation through

the cleft may also be heard at the apex A low-pitched middiastolic

murmur heard at the left lower sternal border may be present if the

shunt is large or if signifi cant left AV valve regurgitation is present

Echocardiography

Two-dimensional echocardiography is the primary imaging

technique for diagnosing AVSDs (19–21) It is useful

par-ticularly for delineating the morphology of the AV valves

Transesophageal echocardiography (TEE) can provide incremental diagnostic information in larger patients or in patients with associated complex abnormalities

The internal cardiac crux is the most consistent diographic imaging landmark (19) The apical four-chamber imaging plane clearly allows visualization of the internal crux where the primum ASD is seen as an absence of the lower atrial septum The size of the primum ASD is made reliably from this imaging position (Fig 29.8) or from the subcostal four-chamber (frontal) projection Accurate visualization of the cardiac crux also permits assessment of the AV valves Sev-eral 2-D echocardiographic features are shared by all forms

echocar-of AVSD: defi ciency echocar-of a portion echocar-of the inlet ventricular tum, inferior displacement of the AV valves, and attachment

sep-of a portion sep-of the left AV valve to the septum The AV valves are displaced toward the ventricles, with the septal portions inserting at the same level onto the crest of the ventricular septum Therefore, in these defects, the two separate AV valve orifi ces are equidistant from the cardiac apex

In the transitional form of partial AVSD, there is mal replacement of a portion of the inlet ventricular septum (21) (Fig 29.9A,B) Small shunts may occur through this so-called “tricuspid pouch.” However these dense chordal attachments eventually obstruct fl ow Spectral and color fl ow Doppler hemodynamic assessments are useful to determine the severity of AV valve stenosis or insuffi ciency and to quantitate right ventricular systolic pressure Doppler echocardiography often is not useful for evaluating the degree of left AV valve stenosis in the setting of a primum ASD because the ASD will decompress the left atrium (LA)

aneurys-Other left AV valve abnormalities are typical with both the tial and complete forms of AVSD (Fig 29.10A) The most common abnormality, a cleft, is best visualized from the parasternal and sub-costal short-axis imaging planes Careful 2-D and color Doppler assessment of the left AV valve cleft needs to be performed since multiple jets of regurgitation may be present LV to right atrium (RA)-directed left AV valve regurgitation is usually remedied dur-ing surgery with successful repair of the cleft and closure of the primum ASD LV to LA regurgitation may not be completely elimi-nated with cleft repair and may signify other intrinsic abnormali-ties with the valve An important factor that predicts the amount

par-of residual postoperative left AV valve regurgitation is the degree par-of preoperative regurgitation Rarely, other abnormalities of the left

AV valve occur such as a parachute or a double-orifi ce valve

development of the AV canal region and the spectrum of AVSD, including partial, transi-tional, complete, and intermediate forms A, anterior leaflet; AB, anterior bridging leaflet;

DDCC, dextrodorsal conus cushion; IEC, inferior endocardial cushion; LEC, lateral endocardial cushion; P, posterior leaflet; PB, posterior bridging leaflet; S, septal leaflet;

SEC, superior endocardial cushion; L, lateral leaflet

view) The atrioventricular septum (AVS) lies between the RA

and the left ventricle (LV) with the interatrial septum (IAS)

above and the interventricular septum (IVS) below The septal

tricuspid leaflet (TV—right AV valve) normally inserts at a

lower (more apical) level than the anterior mitral leaflet (MV—

left AV valve) LA, left atrium; RV, right ventricle (From

Edwards WD Applied anatomy of the heart In: Brandenburg

RO, Fuster V, Giuliani ER, et al., eds Cardiology:

Fundamen-tals and Practice Vol 1 Chicago, IL: Year Book Medical,

1987:47–109, with permission of Mayo Foundation.)

Figure 29.4. Elongate LVOT in AVSD: Because of deficiency of the ventricular component of the AV septum and the “sprung” AV junction, the distance from the LV apex to the posterior left AV valve annulus is 20% to 25%

shorter than the distance from the apex to the aortic annulus Ao, aorta; LA, left atrium; LV, left ventricle; RV, right ventricle (With permission of Robert H Anderson, MD.)

specimen demonstrating a large primum ASD

(arrow), severe RA and RV dilation, and

con-nection of both AV valves to the septum at the

same level Top right: Corresponding apical

four-chamber diastolic image demonstrating

severe RA and RV dilation owing to a large

primum ASD (arrow) Bottom left: Color

Dop-pler scan from the apex, demonstrating a large

left-to-right shunt crossing the primum ASD in

diastole (red flow jet) Bottom right: Systolic

color flow Doppler displaying moderate right

and left AV valve regurgitation LA, left atrium

Double-orifi ce left AV valve occurs in 3% to 5% of AVSDs

(22) This abnormality is more common when two distinct

right and left AV valve orifi ces are present A tongue of tissue

may divide the left AV valve into two orifi ces The combined

effective valve area of a double-orifi ce valve always is less

than the valve area of a single-orifi ce valve This predisposes

the valve to postoperative stenosis Standard subcostal and

parasternal short-axis views usually demonstrate the

double-orifi ce valve characteristics (Fig 29.10B,C) However, in the

setting of a common AV valve, the diagnosis may be

challeng-ing Double-orifi ce left AV valve rarely occurs in hearts that do

not have AVSD In contrast to AVSD, in the otherwise normal

heart, double-orifi ce mitral valves have complete duplication

of the valve structure

In the normal heart, the aortic valve is wedged between the mitral and tricuspid annuli In AVSD, the aortic valve

is displaced or “sprung” anteriorly (Fig 29.11) This rior displacement creates an elongate, so-called gooseneck deformity of the LVOT (Fig 29.12) that predisposes the patient to progressive subaortic obstruction LVOT obstruc-tion may occur in all subtypes of AVSD It is more frequent when two distinct AV valve orifi ces are present rather than when there is a common orifi ce But whenever the superior bridging leafl et attaches to the crest of the ventricular septum,

ante-*

LVRV

LS

A

L

Top left: Systolic apical four-chamber image

demonstrating that both right and left AV valves insert onto the crest of the ventricular septum at

the same level Top right: Corresponding diastolic

frame showing a large primum ASD Systolic frames often understate the size of the interatrial communication There is significant RA and RV

enlargement Bottom panels: These are

paraster-nal short-axis scans focused at the valve leaflet

level in the left ventricular inflow The left panel

demonstrates the cleft in the anterior leaflet of

the left AV valve (asterisk) The anterior leaflet

is made of two separate components that move independently This creates the diastolic gap in

the leaflet (asterisk) Color Doppler on the right

panel shows considerable regurgitation through

the cleft LA, left atrium; LV, left ventricle

Figure 29.7. Cleft left AV valve: Left: In AVSD, the cleft in the anterior leaflet of the left AV valve is typically

oriented toward the midportion of the ventricular septum (arrow) along the anterior–inferior rim of the septal

defect Right: Subcostal sagittal image demonstrating the septal orientation of the cleft A, anterior; PMs,

papil-lary muscles; RV, right ventricle; S, superior

Figure 29.8. AVSD and the internal cardiac crux The internal cardiac crux is best visualized in the apical chamber imaging plane In the normal heart, the anterior leaflet of the mitral insertion is more superiorly fixed than the corresponding tricuspid septal leaflet In all forms of AVSD, both right and left AV valve components insert at the same level on the crest of the inflow ventricular septum A cleft in the left AV valve occurs in con-junction with the downward displacement of the anterior leaflet In partial AVSD, there is a defect in the lower fatty portion of the atrial septum (i.e., within the atrial ventricular septum) In complete AVSD, there is a defect beneath the AV valves in the inflow ventricular septum In general, these easily recognized anatomic features distinguish normal from partial and complete AVSD AVC, atrioventricular canal.

four-B

ASD in a 20-year-old patient with partial AVSD No VSD is present B: In contrast to image 9A, this patient has a

transitional AVSD Note the membranous aneurysm in the inflow ventricular septum (arrows) There is a primum

ASD; clinically, it presents as a partial AVSD There can be restrictive VSDs in the inflow aneurysmal membrane

LA, left atrium; LV, left ventricle; RA, right atrium; RV, right ventricle; VS, ventricular septum

creating two orifi ces, this further elongates and narrows the

LVOT In addition, discrete subaortic fi bromuscular ridges,

septal hypertrophy, abnormal left AV valve chordal

attach-ments, and abnormally oriented papillary muscles can further

exacerbate the subaortic narrowing LVOT obstruction may

be subtle and therefore not appreciated during the

preopera-tive echocardiographic assessment LVOT obstruction may

develop de novo after initial repair of AVSD (23) (Fig 29.13)

The LVOT obstruction often is progressive Even after mary repair of partial AVSD in adulthood, de novo LVOT obstruction may occur The Mayo Clinic has reported the case of a 58-year-old woman who had reoperation for LVOT obstruction after primary repair of partial AVSD at age 45 years (24)

left AV valve anomalies in AVSD A: Cleft left

AV valve The left AV valve has a

characteris-tic break (arrow) that represents a cleft in the

anterior leaflet This is a feature of all forms of

AVSD B: Double-orifice left AV valve imaged

in the subcostal sagittal plane, typically tered with partial AVSD Each papillary muscle

encoun-receives a separate AV valve orifice (arrows)

The anterolateral valve component is

usu-ally cleft C: Parasternal short-axis image of a

double-orifice left AV valve with a cleft (arrow)

in the anterolateral component LV, left cle; RV, right ventricle; VS, ventricular septum

ventri-Figure 29.11. Sprung aortic valve: Left: Normal heart pathologic specimen cut in short axis at the base strating where the AV junction has a figure-of-8 configuration Right: Similar projection in an AVSD heart where

demon-the AV junction is “sprung.” The aortic valve is anterior of demon-the AV junction instead of being wedged between the AV valve annuli

Figure 29.12. Because of the anterior displacement of the LVOT in AVSD, the elongate LVOT has been described as

a “goose neck” with echocardiographic and angiographic imaging Left: subcostal frontal view of the LVOT dle: pediatric and adult goose necks in Minnesota Right: Prograde LV angiograph demonstrating elongate LVOT.

Mid-A

B

obstruction in a 17-year-old who had repair of a partial AVSD at age 15 months LVOT obstruction (arrow) is

usually progressive and may be undetected at time of initial repair B: LVOT obstruction: parasternal long-axis

projection demonstrating left AV valve attachments (arrow) to the septum in a patient after repair of partial AVSD

10% to 15% of patients with AVSD require reoperation to relieve LVOT obstruction Progressive LVOT tion is more common in partial than in complete AVSD Mechanisms of LVOT obstruction include attachments

obstruc-of superior bridging leaflet to ventricular septum, extension obstruc-of the anterolateral papillary muscle into the LVOT, discrete fibrous subaortic stenosis, tissue from an aneurysm of the membranous septum bowing into the LVOT

Detailed and comprehensive echocardiographic

assessment is required to evaluate associated lesions and

determine their signifi cance Tetralogy of Fallot,

double-outlet RV, and pulmonary valve atresia are associated with

all forms of AVSDs but are less frequent with partial AVSD

In contrast, AV valve abnormalities and left ventricular

hypoplasia are more frequent in two-orifi ce AV connections

Coarctation of the aorta occurs with equal frequency in

partial and complete AVSD

Radiography

Typically, chest radiography demonstrates cardiomegaly and

prominent pulmonary vascular markings Because the jet

of mitral regurgitation often is directed into the RA, right

atrial enlargement rather than left atrial enlargement may be

apparent

Electrocardiography and Electrophysiology

The position of the AVSD dictates the position of the AV

conduction tissues Accordingly, the AV node is displaced

pos-teriorly, near the orifi ce of the coronary sinus, and the His

bundle is displaced inferiorly, along the inferior rim of the

septal defect The displacement of the AV conduction tissues,

in conjunction with loss of ventricular septal myocardium,

results in left axis deviation in the frontal plane QRS

Sinus rhythm is present in most patients with a primum

ASD Prolongation of the P-R interval, in relation to patient

age and heart rate, is seen in approximately 25% of patients

It is due primarily to increased conduction time from the

high RA to the low septal RA (25) P-wave changes

indicat-ing right atrial, left atrial, or biatrial enlargement are seen in

approximately half of patients The mean QRS axis in the

frontal plane ranges from −30 degrees to −120 degrees, with

most axes between −30 degrees and −90 degrees Anatomic

and electrophysiologic studies show that this abnormal

vectorcardiographic pattern is associated with a specifi c

anom-aly of the conduction system (26) Right ventricular volume

overload results in right ventricular hypertrophy and some

variation of the rsR′ or RSR′ pattern in the right precordial

leads in 80% of patients; 10% of patients have a qR pattern

Patients with signifi cant left AV valve regurgitation may have

evidence of left ventricular hypertrophy

Except for prolonged intra-atrial conduction time, other

intracardiac electrophysiologic measurements usually are

nor-mal, including sinus node function, AV node function,

His-Purkinje conduction time, and refractory periods (25)

Cardiac Catheterization and Angiography

Cardiac catheterization and angiography rarely are necessary

for diagnosis or management of patients with a partial AVSD

Current echocardiographic techniques accurately defi ne the

anatomy and physiology of this lesion In an older patient,

cardiac catheterization may have a role in assessing the degree

of pulmonary vascular obstructive disease or coronary artery

disease

A large left-to-right shunt can be demonstrated at atrial

level by a higher oxygen saturation sampled from the RA

compared with the blood in the inferior and superior vena

cavae Because of the anatomic position of the ASD, blood

samples taken from the infl ow portion of the RV may have

elevated oxygen saturation The calculated left-to-right shunt

often exceeds 50% In most patients, right ventricular

pres-sure is <60% of systemic prespres-sure A signifi cant increase in

calculated pulmonary vascular resistance is unusual in infants

Left ventricular angiography will demonstrate the elongate gooseneck deformation of the LVOT (Fig 29.12)

Special Forms of Partial Atrioventricular Septal Defect

Malaligned Atrial Septum or Double-Outlet Right Atrium

Deviation of the atrial septum to the left of the AV tion has been reported rarely (27,28) When this occurs, both the right and left AV valves are visualized from the

junc-RA, which is connected to both ventricles through a large primum ASD If deviation of the atrial septum to the left is extreme, the pulmonary veins may be isolated and obstructed, simulating cor triatriatum Although the term

“double-outlet” RA has been applied to this lesion (29), it is truly a form of AVSD

Common Atrium

Common atrium is characterized by near absence of the atrial septum In the presence of two ventricles, it always is associ-ated with an AVSD (30) Cases of common atrium typically are syndromic The most common syndromes are asplenia, polysplenia, and Ellis-van Creveld (9–11) The pathologic spectrum of this lesion ranges from patients with coexistent primum and secundum ASDs to others who lack the entire septum except for a small muscular cord Patients with syn-dromes and common atrium frequently have concomitant complex congenital heart disease In these cases, transposi-tion of the great arteries, double-outlet RV, univentricular

AV connection, and anomalous pulmonary venous tions often are encountered Patients with common atrium frequently have anomalies of cardiac and abdominal situs as well as asplenia

connec-Clinical Manifestations Most patients with common

atrium present in infancy with symptoms of excess nary blood fl ow, fatigue, tachypnea, and failure to thrive

pulmo-However, if increased pulmonary vascular resistance ops, the left-to-right shunt decreases and somatic growth improves In general, these patients are symptomatic earlier

devel-in life than patients with only a primum ASD The graphic and electrocardiographic characteristics of patients with common atrium are indistinguishable from those with other forms of AVSD

radio-Echocardiography The subcostal four-chamber imaging

plane is most suitable for accurate diagnosis A muscle bundle

or band coursing through the atrium should not be preted as an atrial septum

misinter-Cardiac Catheterization and Angiography The

hemo-dynamic diagnosis of common atrium depends on the onstration of complete mixing of systemic and pulmonary venous blood The oxygen saturations of pulmonary and systemic arterial blood are nearly identical Pulmonary blood

dem-fl ow exceeds systemic dem-fl ow, except in patients with severe monary vascular obstructive disease Right ventricular pres-sure is increased more often than in secundum ASD or partial AVSD If defi nitive repair is delayed, signifi cant pulmonary vascular obstructive disease may develop at an earlier age than

pul-in patients with isolated secundum ASD or partial AVSD

Treatment Prior to surgical repair, medical therapy usually

is instituted when signs and symptoms of excess pulmonary blood fl ow and failure to thrive are present Digoxin and diu-retic therapy are traditional forms of therapy Common atrium requires surgical repair, which should be performed early in life because patients usually have symptoms and there is a risk for early development of pulmonary vascular obstructive disease

COMPLETE ATRIOVENTRICULAR SEPTAL DEFECT

Pathology

The complete form of AVSD is characterized by a large

sep-tal defect with interatrial and interventricular components and

a common AV valve that spans the entire septal defect (30)

(Fig 29.14) The septal defect extends to the level of the

mem-branous ventricular septum, which is usually defi cient or absent

The common AV valve has fi ve leafl ets The posterior

bridg-ing leafl et drapes over the inlet ventricular septum and

concep-tually represents fusion of the septal tricuspid leafl et and the

inferior half of the anterior mitral leafl et Two lateral leafl ets

correspond to the posterior tricuspid and posterior mitral

leafl ets in a normal heart The right-sided anterior leafl et, in

essence, represents the normal anterior tricuspid leafl et, and the

so-called anterior bridging leafl et corresponds to the superior

half of the anterior mitral leafl et The extent to which the

ante-rior bridging leafl et actually straddles into the RV varies

con-siderably and has formed the basis for a classifi cation system of

complete AVSD into types A, B, and C (see below) The

com-mon AV valve may be divided into distinct right and left orifi ces

by a tongue of tissue that connects the two bridging leafl ets,

representing the rare intermediate form of complete AVSD

Beneath the fi ve commissures are fi ve papillary muscles The

two left-sided papillary muscles are oriented closer together

than in a normal heart, such that the lateral leafl et is smaller

than a normal posterior mitral leafl et In addition, the two

papillary muscles often are rotated counterclockwise, such

that the posterior muscle is farther from the septum than

nor-mal and the anterior muscle is closer to the septum This

papil-lary muscle arrangement, in conjunction with prominence of

an anterolateral muscle bundle, may contribute to progressive

LVOT obstruction Moreover, the leafl ets are prone to develop

progressive regurgitation and, with time, they become

thick-ened and exhibit hemodynamic and structural changes similar

to that associated with mitral valve prolapse (31)

The potential for interventricular shunting exists along

the septal surface between the two bridging leafl ets and at the

interchordal spaces beneath the leafl ets The posterior

bridg-ing leafl et characteristically overhangs the ventricular septum

and has extensive septal chordal attachments Occasionally,

chordal fusion obliterates the interchordal spaces beneath this

leafl et The anatomic relationship between the anterior

bridg-ing leafl et and the ventricular septum is variable and forms

the basis for a classifi cation described by Rastelli et al (32)

(Fig 29.15)

Rastelli Classifi cation for Complete Atrioventricular

Septal Defect

Giancarlo Rastelli died in 1970 at 36 years of age (33)

Dur-ing his abbreviated life and brilliant but short career, he made

many landmark contributions to the fi eld of congenital heart

disease In the 1960s, he devoted much of his time to

obtain-ing a better understandobtain-ing of the morphology of the common

AV valve in patients with AVSD The classifi cation scheme that

now bears his name was based on the morphology of the

ante-rior bridging leafl et The improved understanding of the AV

valve diversity aided surgeons and improved operative

mor-tality for these patients Prior to 1964, hospital mormor-tality for

patients with AVSD was 60% Rastelli et al (34) from the

Mayo Clinic published their work in 1968 and operative

mor-tality between 1964 and 1967 decreased to 20% The

clas-sifi cation scheme that Rastelli described is listed below and

summarized in Table 29.2

In type A (most common), the anterior bridging leafl et

inserts entirely along the anterosuperior rim of the ventricular

septum It forms a true commissure with the right-sided anterior leafl et Beneath this commissure is either a distinct medial papillary muscle or, more commonly, multiple direct chordal insertions along the septum Interventricular commu-nication beneath the anterior bridging leafl et may be minimal

or absent in some cases owing to extensive interchordal fusion

In type B (least common), the anterior bridging leafl et is larger and the right-sided anterior leafl et is smaller than in type A As a result, the bridging leafl et straddles the septum and is associated with papillary muscle attachment along the septal or moderator band in the RV Because chordal anchors are not present between the anterior bridging leafl et and the underlying ventricular septum, free interventricular commu-nication exists

In type C, the anterior bridging leafl et is larger than in type

B, and its medial papillary muscle attachments fuse to the right-sided anterior papillary muscle As a result, this leafl et

is generally very small Because the anterior bridging leafl et is not attached to the ventricular septum, free interventricular communication is possible, and the leafl et has been described

as “free fl oating.”

The subtype of complete AVSD has some bearing on the likelihood of associated lesions Type A usually is an isolated defect and is frequent in patients with Down syndrome In contrast, type C is encountered with other complex anoma-lies, such as tetralogy of Fallot, double-outlet RV, complete transposition of the great arteries, and heterotaxy syndromes (35,36) Coronary artery anomalies, when they occur, tend

to be associated with coexistent conotruncal malformations rather than the AVSD The combination of type C complete AVSD with tetralogy of Fallot is observed in patients with Down syndrome, whereas double-outlet RV is a feature of patients with asplenia

Clinical Manifestations

Tachypnea and failure to thrive invariably occur early in infancy as a result of excessive pulmonary blood fl ow Virtu-ally all patients with complete AVSD have symptoms by 1 year

of age If these symptoms do not develop early on, the clinician should suspect premature development of pulmonary vascular obstructive disease AV valve regurgitation compounds these problems After surgical repair, left AV valve regurgitation is the most common reason for reoperation A recent study dem-onstrated that 22% of patients who had undergone repair of complete AVSD had more than moderate left AV valve regurgi-tation at 6 month follow-up (2) Although single-center reports have identifi ed preoperative AV valve regurgitation as an important risk factor for reoperation (37), it failed to predict greater than moderate postoperative AV regurgitation in the PHN study (2) Greater than moderate AV valve regurgitation within 1 month of surgery was a strong predictor of persistent

AV regurgitation at 6 month follow-up Regression of operative left AV valve regurgitation was not demonstrated in that study (2) in contrast to anecdotes that this occurs

post-If severe pulmonary vascular obstructive disease is absent, there may be no systemic arterial oxygen desaturation The physical examination demonstrates a hyperactive precor-dium and an accentuated fi rst sound, and the second sound may move with respiration but it is quite variable Because

of elevated pulmonary artery pressures, the pulmonary sure sound is accentuated A loud S1-coincident holosystolic murmur can be heard along the lower left sternal border and

clo-at the cardiac apex if left AV valve regurgitclo-ation is present

A separate crescendo–decrescendo systolic ejection murmur is heard over the upper left sternal border as a result of increased pulmonary blood fl ow A middiastolic murmur can be heard along the lower left sternal border and frequently at the apex

tion, showing an unbalanced form of AVSD with dilation of a common inlet RV, leftward septal bowing, and a

hypoplastic LV F: Four-chamber view of a complete AVSD associated with right atrial isomerism, mirror-image

ventricles (L-loop ventricular inversion), and asplenia Ao, aorta; CS, coronary sinus; LA, left atrium; LV, left ventricle; PA, pulmonary artery; RA, right atrium; RV, right ventricle

as a result of increased blood fl ow across the common AV

valve However, the physical examination fi ndings of complete

AVSD may be indistinguishable from those of an

uncompli-cated large VSD or partial AVSD

Echocardiography

Two-dimensional echocardiography is the primary diagnostic

tool for evaluation of complete AVSD (19,20,38) As described

earlier, assessment of the internal cardiac crux from the

api-cal and subcostal four-chamber projections provides excellent

detail of the size and locations of defects in both the atrial and

ventricular septa (Fig 29.16) Additional secundum ASD, a

fairly common associated fi nding, can be detected from the

subcostal four-chamber coronal view and with clockwise

rota-tion of the transducer from the subcostal sagittal imaging plane (21) The VSD is located posteriorly in the inlet sep-tum Both right- and left-sided components of the common

AV valve are displaced toward the ventricles and are ated with variable defi ciency of the infl ow ventricular septum

associ-A PDassoci-A is a common associated fi nding In the PHN report, 44% of patients had PDA ligation at the time of AVSD repair

Suprasternal notch and high left parasternal imaging should

be performed to evaluate the PDA However, in the setting of massive pulmonary blood fl ow from a complete AVSD, aliased color Doppler signals in the branch pulmonary arteries may make small PDAs diffi cult to appreciate Fortunately, surgeons routinely check for ductal patency at the time of AVSD repair

Spectral and color Doppler serve as adjuncts to assess the sites

of shunting, severity of AV valve regurgitation, and tions of the pulmonary veins Fetal echocardiography read-ily detects complete AVSD in standard four-chamber views (Fig 29.17)

connec-When communicating with a surgeon, the pher must describe the morphology of the AV valve in pre-cise detail The surgeon needs to know the competence and ventricular commitment of the AV valve orifi ces and whether

echocardiogra-a tongue of tissue connects the superior echocardiogra-and inferior

bridg-ing leafl ets to form two distinct orifi ces The subcostal en face

view is essential for this determination This view is obtained with counterclockwise rotation from the four-chamber coro-

nal view until the AV valve leafl ets appear en face (Fig 29.18)

Deliberate superior and inferior angulation of the probe will permit inspection of the cross section of all fi ve valve leafl ets

The valve is inspected from the inferior margin of the atrial septum to the superior margin of the ventricular septum (38)

In the operating room, the TEE transgastric short-axis view will aid in this assessment

A single left ventricular papillary muscle may occur in complete AVSD Similar to the double-orifi ce valve, a sin-gle papillary muscle will reduce the effective valve area and complicate the surgical repair Left AV valve repair may be

A: Type A complete AVSD The defect is characterized by insertion of the anterior bridging leaflet to the crest of

the ventricular septum (VS) B: Type B complete AVSD The defect is characterized by dominant insertion of the

anterior leaflets into papillary muscles in the RV In this example, the anterior bridging leaflet inserts onto the

crest of the ventricular septum, as well as onto a large ventricular papillary muscle (P) (arrow in echocardiogram)

C: Type C AVSD The anterior leaflet is unattached (arrow) and overrides the crest of the ventricular septum

The free anterior leaflet does not insert onto the crest of the ventricular septum A, anterior; P, posterior; L, left;

LA, left atrium; LV, left ventricle; R, right; RA, right atrium; S, superior (Modified from Seward JB, Tajik AJ,

Edwards WD, et al Two-Dimensional Echocardiographic Atlas Vol 1 Congenital Heart Disease New York,

NY: Springer-Verlag, 1987:270–292, with permission.)

Rastelli

Type Anterior Bridging Leafl et and Chordae

A Divided and attached to crest of ventricular

septum Multiple chordae

B Partly divided, not attached to crest of the

septum Chordae attach to papillary muscle in

RV usually on septal surface

C Not divided and not attached to the crest of

the septum (“free floating”) Chordae attach

to papillary muscle on RV free wall

29.2

TABLE Rastelli Classifi cation for

Complete AVSD

compromised further by relative leafl et hypoplasia

Echocar-diographic imaging techniques for this abnormality are similar

to those for double-orifi ce left AV valve

The Concept of “Balance”

Two-dimensional echocardiography is essential for

determin-ing the relative sizes of the ventricles In AVSD, the AV valves

(regardless of number of orifi ces) may be more committed

to one ventricle at the expense of fl ow into the other This

will lead to relative hypoplasia of the underperfused

ventri-cle Both partial and complete AVSDs can be “balanced” or

“unbalanced” based on how the AV junction is shared by the

ventricles If the AV inlet is equally shared by both ventricles,

then this is consistent with a “balanced” AVSD

In unbalanced AVSD, one ventricle is typically hypoplastic,

although the common AV valve is its usual size (Fig 29.19)

The larger ventricle is termed the “dominant” ventricle

Unbal-anced AVSD occurs in approximately 10% of all AVSDs

Two-thirds of unbalanced AVSDs are right ventricular dominant

When the RV is dominant, the LV is hypoplastic, and more

than half of the AV junction is committed to the RV These

patients frequently have severe coarctation of the aorta and

aortic arch anomalies Conversely, unbalanced AVSD with

a dominant LV has a hypoplastic RV and is associated with

pulmonary valve stenosis or atresia Interestingly, in children with Down syndrome and unbalanced AVSD, left ventricular dominance is common

With standard 2-D echocardiographic imaging, both tricles are appreciated from the apical four-chamber view

ven-This imaging plane allows visualization of malalignment between the atrial and ventricular septa This can be a clue

to an unbalanced AVSD The subcostal sagittal view gives an estimate of the proportion of the AV valve committed to each ventricle Determining “balance” with echocardiographic imaging is important as it forms the basis for deciding single-ventricle versus biventricular surgical repair Modest degrees

of right ventricular hypoplasia also may be addressed with a

“1.5-ventricle repair.” In this situation, intracardiac shunts are repaired and the RV is unloaded by performing a bidirectional cavopulmonary connection

Cohen et al (39) (Fig 29.20) proposed a quantitative approach using the subcostal sagittal view to delineate cases with signifi cant left ventricular hypoplasia that may be bet-ter treated with a single-ventricle approach They measured the area of the AV valve apportioned over each ventricle and calculated an AV valve index (AVVI) This serves as an LV/RV area ratio The AVVI may be used as the basis for an algorithm

to stratify patients into a single-ventricle versus a two-ventricle surgical pathway Those with an AVVI <0.67 who have a large VSD would be considered for the single-ventricle pathway

four-chamber images in systole (left) and diastole

(right) demonstrating a complete AVSD with

large primum ASD (asterisk), large inlet VSD (arrow), and common single-orifice AV valve

The right panel demonstrates the valve opening

as a single unit with only lateral “hinge points”

visible in this image Biventricular volume load and a small secundum ASD are present in this patient

four-chamber images in diastole (left), systole (center), and systole with color Doppler (right) demonstrating a

com-mon atrium, comcom-mon AV valve, and comcom-mon ventricle After delivery, this child was found to also have asplenia

PS

RV

LV

Figure 29.18. Subcostal sagittal imaging of common AV valve: Subcostal sagittal images in systole (left) and

dias-tole (right) in a patient with complete AVSD The right panel demonstrates the anterior bridging leaflet (arrow)

of the common AV valve This leaflet crosses (bridges) the VSD anteriorly and is shared by both ventricles It is not divided into right and left components and has no attachments to the ventricular septum This morphology

is also called free floating or Rastelli type C During repair, unlike the naturally divided anterior bridging leaflet (type A), this leaflet must be incised into right and left components before attachment to the VSD patch

LV Dominant RV Dominant

Figure 29.19. Right versus left ventricular dominance,

based on a classification scheme from Bharati and Lev:

Left ventricular dominance (left panels) and right

ven-tricular dominance (right panels) are demonstrated In

the LV-dominant case, the common AV valve opens

predominantly into the LV Conversely, in the

RV-dominant case, the common AV valve opens

predomi-nantly into the RV LA, left atrium; LV, left ventricle;

RA, right atrium; RV, right ventricle

The clinician must be aware of several caveats that may

make interpretation of “ventricular balance” less

straight-forward For example, the severity of valve malalignment

may not necessarily correlate with the degree of ventricular

hypoplasia Moreover, pulmonary venous blood

preferen-tially crosses the ASD causing underfi lling of the LV Finally,

the presence of a large left-to-right shunt may cause severe right ventricular enlargement with bowing of the septum to the left This will lend an appearance of “hypoplasia” to the

LV van Son et al (40) attempted to estimate the tial volume” of the LV preoperatively by using a theoreti-cal model that calculates the relative areas of the LV and

“poten-RV in short axis after assuming normal septal confi guration

(Fig 29.21)

All of these methods should be employed when assessing a

patient with an unbalanced AVSD One must realize that none of

these methods factor in patient/cardiac growth It also is

impor-tant to know if the LV is apex forming Generally patients with

unbalanced AVSD may present many challenges both from the echocardiographic imaging and clinical management perspectives

Radiography

The heart usually is enlarged in patients with complete AVSD

Enlargement of the RA is suggested by increased convexity of the right heart border, and left atrial enlargement may pro-duce a characteristic fl attening of the left heart border The pulmonary artery is prominent, and the pulmonary vascular markings are increased

Electrocardiography

Prolongation of the P-R interval is observed in approximately 25% of patients with AVSD (25) Intracardiac studies have revealed increased intra-atrial or AV node conduction times

as the cause of P-R prolongation More than 50% of patients meet voltage criteria for atrial enlargement A superior or northwest QRS axis is common (Fig 29.22) The QRS axis in the frontal plane lies between −60 degrees and −135 degrees, with most patients having an axis between −90 degrees and −120 degrees Most patients have an rsR, RSR′, or Rr′ in lead V1, and others have a qR or R pattern in the same chest lead, all indicating right ventricular hypertrophy Left ventric-ular hypertrophy may also be present

Cardiac Catheterization and Angiography

Cardiac catheterization and angiography rarely are needed for management of infants with complete AVSD In an older child, when pulmonary vascular obstructive disease is suspected, there is a role for determining pulmonary vascular resistance

Severe pulmonary vascular obstructive disease (pulmonary vascular resistance of >10 U·m2) is rare but has been reported

in infants <1 year of age

RV dominant

Balanced

valve area measurements Left panel: Diastolic frame from the subcostal sagittal plane demonstrating an en face

view of the common AV valve The planimetry demonstrates relative balance between the right and left portions

of the common valve Center panel: Diastolic frame demonstrating an RV-dominant unbalanced AVSD with relative dominance of the right portion of the common AV valve Right panel: Companion systolic frame of an

RV-dominant AVSD (From Cohen M, Jacobs ML, Weinberg PM, et al Morphometric analysis of unbalanced

common atrioventricular canal using two-dimensional echocardiography J Am Coll Cardiol 1996;28:1017, with

permission.)

unbalanced AVSD Due to right ventricular volume overload,

the septum bows toward the LV This may provide the

misper-ception that the LV is hypoplastic However, if one assumes

normalization of septal position, the potential volume of the

LV after repair may be predicted (From van Son JAM, Phoon

CK, Silverman NH, et al Predicting feasibility of biventricular

repair of right-dominant unbalanced atrioventricular canal

Ann Thorac Surg 1997;63:1657, with permission.)

Cardiac catheterization demonstrates increased oxygen

saturation at both the right atrial and the right ventricular

levels In complete AVSD, pulmonary artery systolic pressure

invariably is at or near systemic level However, in partial

AVSD, pulmonary artery systolic pressure usually is <60%

of systemic pressure Pulmonary blood fl ow is increased as a

result of left-to-right shunting at both atrial and ventricular

sites, and the degree of shunting depends upon the

relation-ship of pulmonary to systemic vascular resistance The

hemo-dynamic abnormality in complete AVSD may be complicated

by severe common AV valve regurgitation, allowing blood

to shunt freely among all cardiac chambers Left ventricular

angiography rarely is required but reveals the typical LVOT

gooseneck deformity and varying severity of left AV valve

regurgitation

Clinical Course

Infants with complete AVSD typically will require medical

therapy with diuretics, sometimes augmented with digoxin or

angiotensin-converting-enzyme inhibitors depending on the

specifi c clinical situation The timing of surgical intervention

must take into account the propensity of pulmonary vascular

disease to develop in these patients at an early age The

deci-sion for operation is usually made in the fi rst 6 months of life

Children with complete AVSD frequently have surgical repair

between 3 and 6 months of age But, children with Down

syn-drome may require surgical intervention at an earlier age due

to their propensity to develop pulmonary vascular obstructive

changes

Special Forms of Complete Atrioventricular

Septal Defect

Intermediate Defect

A rare subtype of complete AVSD occurs when the anterior

and posterior bridging leafl ets are fused atop the

ventricu-lar septum and the common AV valve is divided into

dis-tinct right and left orifi ces This defect usually has a large

primum ASD and a large inlet VSD Patients present in the

same manner as with other forms of complete AVSD

Surgi-cal repair does not have to include division of separate right

hypertrophy are present

and left AV valve components (this has occurred naturally)

The cleft in the left AV valve is closed, but the bridging lets often have insuffi cient tissue to reconstruct a competent anterior leafl et

leaf-Down Syndrome and Atrioventricular Septal Defect

Down syndrome occurs in more than half of patients with complete AVSD Children with Down syndrome and complete AVSD also are more likely to have associated tetralogy of Fal-lot (41,42) In contrast, sidedness (situs) and splenic anomalies are rare in patients with Down syndrome Patients with Down syndrome usually do not have associated LVOT obstruc-tion, left ventricular hypoplasia, coarctation of the aorta, or additional muscular VSDs (43,44) In cases with unbalanced AVSD, patients with Down syndrome have LV dominant mor-phology more frequently than RV dominance

The extent and progression of pulmonary vascular changes in children with Down syndrome and complete AVSD remain controversial Histologic studies (45) have failed to show any differences in the extent of pulmonary vascular changes when patients with Down syndrome were compared with normal children who also had AVSD Other studies (46,47) have suggested that children with Down syn-drome have relative pulmonary parenchyma hypoplasia and develop pulmonary vascular obstructive disease appreciably earlier than patients with normal chromosomes and com-plete AVSD

The hemodynamic assessment of children with Down drome must take into account that these patients may have chronic nasopharyngeal obstruction, relative hypoventilation, and sleep apnea These factors contribute to carbon dioxide retention, relative hypoxia, and elevated pulmonary vascular resistance

syn-Patients with Down syndrome have a higher ratio of monary to systemic resistance than patients without Down syndrome (48) This difference resolves with administration of 100% oxygen, suggesting that apparent hypoxia and hypoven-tilation are factors that can be corrected during hemodynamic study Fixed and elevated pulmonary vascular resistance has been demonstrated in 11% of Down syndrome patients

pul-<1 year of age (48) In the current era, timing of repair and surgical outcome for patients with Down syndrome are similar

to those of the general population (2,49)

INITIAL SURGICAL TREATMENT OF AVSD

Partial Atrioventricular Septal Defect

The objectives of surgical repair include closure of the

intera-trial communication and restoration and preservation of left

AV valve competence These objectives can be accomplished

by careful approximation of the edges of the valve cleft with

interrupted nonabsorbable sutures On occasion, it is

neces-sary to add eccentric annuloplasty sutures, typically in the

area of the commissures to correct persistent central leaks

The repair is completed by closure of the interatrial

commu-nication (usually with an autologous or bovine pericardial

patch), avoiding injury to the conduction tissue (50) This

repair results in a two-leafl et valve Rarely, if the left AV valve

is considered a trileafl et valve, with the cleft viewed as a

com-missure, the commissure may be left unsutured and

annu-loplasty sutures can be placed to promote coaptation of the

three leafl ets In the recent PHN study, the cleft was closed in

98% of cases (1)

However, the morphologic concepts and surgical methods

favored by Carpentier (51) and Piccoli et al (52) continue to

be debated The PHN investigators could not demonstrate

that annuloplasty decreased the prevalence of left AV valve

regurgitation 6 months after surgery In that study, 18 of

59 patients (31%) who had 6 month postoperative

echocardi-ography data available demonstrated moderate or greater left

AV valve regurgitation (1) Because the details of annuloplasty

were not available in all operative reports, the PHN study

loosely defi ned “annuloplasty” as any additional intervention

on the left AV valve beyond cleft closure This limits the ability

to assess specifi c surgical techniques At Mayo Clinic, the left

AV valve cleft is usually closed and, if needed, limited

annu-loplasty sutures are placed near the commissures to improve

valve competence

The risk of hospital death after surgical repair of partial

AVSD is approximately 1% (1) The timing of repair for

par-tial AVSD trended to an earlier age in the PHN study The

median age of repair for patients with partial AVSD was

1.8 years Long-term survival after repair of partial AVSD is

good In a series of 334 patients from Mayo Clinic, 20- and

40-year survivals after repair of partial AVSD were 87% and

76%, respectively (53) Closure of the left AV valve cleft

and age <20 years at time of operation were associated with

improved survival Reoperation was performed for 11% of

these patients Repair of residual/recurrent left AV valve

regur-gitation or stenosis was the most common reason for

reop-eration (53) In the PHN study, residual ASD shunts (<1%)

and left AV valve stenosis (1%) were rare (1) Residual left

AV regurgitation remains the major reason for reoperation In

that study, 31% of patients had at least moderate

regurgita-tion 6 months after surgery for partial AVSD repair Repair

after age 4 years was a risk factor for residual moderate–severe

left AV valve regurgitation (1)

A low frequency of postoperative arrhythmias has been

noted The fi nding of surgical complete heart block has been

uncommon and would require permanent pacemaker

implan-tation Late onset of atrial fl utter has been rarely encountered

Complete Atrioventricular Septal Defect

Surgical repair of complete forms of AVSD is indicated early in

life The median age at time of repair in the recent multicenter

report was 3.6 months (2) Repair of complete AVSD must be

performed prior to the development of irreversible pulmonary

vascular obstructive disease Repair typically is performed

between 3 and 6 months of age Earlier repair should be

con-sidered for infants with failure to thrive

For the symptomatic infant, surgical options include palliative pulmonary artery banding or complete repair of the anomaly

Silverman et al (54) reported excellent results of pulmonary banding in 21 infants with complete AVSD who were <1 year

of age In that series, there was one surgical death (5%), and the remaining patients had excellent palliation Williams et al (55) recommended pulmonary artery banding for infants weighing

<5 kg who were unresponsive to medical treatment or had nifi cant associated anomalies In the modern era, most centers perform complete repair in small infants who fail to thrive This approach has largely obviated the need for pulmonary artery band placement Investigators in the PHN study found that age

sig-at repair <2.5 months frequently was associsig-ated with rent procedures that likely drove the early timing of surgery In that study, infants who required early repair had similar out-comes in respect to residual shunts and severity of left AV valve regurgitation, but they were more likely to require circulatory arrest, prolonged intensive care unit stays, and increased dura-tion of hospitalization due to their comorbidities (2)

concur-The objectives of surgical repair include closure of trial and interventricular communications, construction of two separate and competent AV valves from available leafl et tissue, and repair of associated defects Techniques for the sur-gical repair of complete AVSD have been standardized and are based on the use of a single patch or double patch (separate atrial and ventricular patches) to close the ASD and VSD and then reconstruction of the left AV valve as a bileafl et valve

intera-(Figs 29.23, 29.24) Puga and McGoon (56) have described these techniques in detail Piccoli et al (52) and Studer et al

(57) consider the cleft of the left AV valve to be a true sure and envisioned this valve as a trileafl et valve On the basis

commis-of these concepts, Carpentier (51) preferred the two-patch technique and the left AV valve remained a trileafl et structure (Fig 29.25) More recently, the “Australian” single-patch technique with primary suture closure of the VSD and peri-cardial patch closure of the ASD has been described (58,59)

Investigators in the PHN study evaluated the various cal techniques utilized to repair complete AVSD (2) In that study, the cleft was closed in 93% of cases The two-patch technique was used in 72% of cases, the single-patch tech-nique in 18%, and the Australian repair in 10% Choice of repair depended on surgeon/center preference The Australian technique was used in younger patients and required return

surgi-to cardiopulmonary bypass (CPB) more frequently than the single- or two-patch techniques The single-patch technique had longer CPB and aortic cross-clamp times but no patients repaired with this technique needed to return to CPB Opera-tive mortality, hospital stay, residual shunt, and signifi cant left

AV valve regurgitation were similar with all techniques (2)

In the modern era, hospital mortality was 2.5% (2) Left

AV valve regurgitation was the most common reason for eration and occurred in 4% of cases within 6 months of ini-tial repair Similar to previous reports, approximately 25% of patients had at least moderate residual left AV valve regurgita-tion Residual shunts were rare and usually closed spontane-ously within 6 months

reop-At most centers, the current approach is to offer repair for complete AVSD at age 3 to 6 months If a child is failing to thrive

or has excessive pulmonary blood fl ow or heart failure, repair

is offered at an earlier age Surgeons at many North American centers prefer to utilize a two-patch technique thereby avoiding division of the bridging leafl ets (60) (Figs 29.23 and 29.24) If the VSD is shallow, a single-patch technique is considered with primary VSD closure (Australian technique) (Fig 29.25) The left AV valve cleft typically is closed and eccentric annuloplasty sutures are utilized to gain valve competence Intraoperative TEE is utilized in all AVSD cases If TEE demonstrates more than mild left AV valve regurgitation, then CPB is resumed and aggressive attempts are made to improve valve competency (61)

Special Problems in Complete AVSD SurgeryParachute Deformity of the Left AV Valve This problem has

been addressed by David et al (62) With such a ity, closure of the cleft at the time of repair may result in an obstructed orifi ce If the patient has signifi cant left AV valve regurgitation with a parachute deformity, then valve replace-ment may be the only suitable option

deform-Double-Orifi ce Left AV Valve The surgeon must resist the

temptation to join the two orifi ces by incising the intervening leafl et tissue The combined opening of both orifi ces is satis-factory for adequate left AV valve function (63)

Right or Left Ventricular Hypoplasia These anomalies may

be severe enough to preclude septation The only option for defi nitive surgical treatment is the modifi ed Fontan procedure preceded by adequate pulmonary artery banding in infancy (64)

Tetralogy of Fallot In patients with this anomaly, all of

whom have complete AVSD, the infundibular septum is placed anteriorly, so that the inlet VSD extends anteriorly and superiorly toward the perimembranous area In tetralogy of Fallot, there is obstruction of the right ventricular outfl ow tract These cyanotic infants often initially are treated with a systemic-to-pulmonary artery shunt and then with “complete repair” at 2 to 4 years of age The intracardiac repair of these hearts is best accomplished through a combined right atrial and right ventricular approach (42)

dis-Subaortic Stenosis If discovered at the time of initial

preoperative evaluation, subaortic stenosis tends to be of the

fi bromuscular membrane type and should be treated by priate resection during surgical repair However, subaortic stenosis may appear late after surgical repair of AVSD The

appro-Figure 29.23. The traditional single-patch repair of complete

AVSD (surgical view from the RA) Note that one patch is

utilized to close both the VSD and ASD The ventricular

component of the single patch is seen deep to the AV valves

This patch is positioned by dividing the bridging leaflets

Once the patch is sutured into place, the bridging leaflets are

resuspended to the patch The cleft in the left AV valve has

been closed

(surgical view from the RA) The first patch is utilized to close

the VSD and is demonstrated deep to the AV valves The

bridg-ing leaflets are not divided Once the VSD patch is placed and

the cleft is repaired, a second patch is utilized for ASD repair

tech-nique (surgical view from the RA) The bridging leaflets are

sutured down directly to the VSD crest Note that the AV valve leaflets appeared “tucked” to the crest of the septum

Once this is performed, a single patch is utilized to repair the remaining ASD

stenosis may be related to the uncorrected defi ciency in the

inlet septum The obstruction usually is due to the formation

of endocardial fi brous tags and fi bromuscular ridges Usually

it can be treated by local resection, although in some patients,

a modifi ed Konno procedure may be necessary (65–68)

REOPERATION AFTER REPAIR OF

ATRIOVENTRICULAR SEPTAL DEFECT

Partial Atrioventricular Septal Defect

Late reoperation following repair of partial AVSD may be

required for regurgitation or stenosis of the left AV valve,

sub-aortic stenosis, regurgitation of the right AV valve, or residual

ASD Reoperation for left AV valve regurgitation occurs in

10% to 15% of survivors of primary repair of partial AVSD

Risk factors for reoperation include signifi cant residual left AV

valve regurgitation as assessed intraoperatively at the time of

initial repair, the presence of a severely dysplastic valve, and

failure to close the cleft in the anterior (septal) leafl et Repeat

valve repair is possible if the dysplasia is not severe or when

the mechanism of regurgitation is through a residual cleft

Eccentric commissural annuloplastic sutures often are needed

to correct central regurgitation Replacement of the valve may

be required in the presence of a severe dysplasia

Reoperation for left AV valve stenosis may be necessary

if the valve orifi ce is hypoplastic, or if the orifi ce is restricted

owing to a parachute deformity of the subvalvular apparatus

Patient–prosthetic mismatch in patients who required valve

replacement during infancy or early childhood will merit valve

re-replacement Relief of prosthetic left AV valve stenosis

result-ing from a small annulus is technically challengresult-ing The small

valve requires replacement with a larger prosthesis, and there

are no reliable techniques for annular enlargement Thorough

debridement and excision of fi brous scar and old prosthetic

material is necessary In rare circumstances, the new larger

prosthesis is sewn into the LA in a supra-annular position

Late LVOT obstruction owing to subaortic stenosis occurs

more frequently after correction of partial AVSD than with

complete AVSD This is likely due to the fact that during the

conventional repair, the defi cient portion of the inlet

ventricu-lar septum is not reconstructed so that the anterior (septal)

leafl et of the left AV valve hinges on the line of fi brous fusion

to the crest of the ventricular septum Thus, the standard

sur-gical repair does not modify the elongated and potentially

nar-rowed LVOT This is in contrast to complete AVSD in which

the defi cient inlet septum is reconstructed with the subvalvular

patch that effectively widens the outfl ow tract Relief of LVOT

obstruction can be accomplished in several ways, including

transaortic resection of the fi brous or fi bromuscular membrane

and patch enlargement of the LVOT with a transaortic and right ventricular approach (modifi ed Konno procedure) Oth-ers have described alternative approaches, including recon-struction of the defi cient inlet septum, septal myectomy, and apicoaortic conduits (65–68) Reoperation for an isolated residual or recurrent ASD is rare after repair of partial AVSD

Stulak et al (69) recently reported the Mayo Clinic experience with 93 patients who had reoperation after initial repair of par-tial AVSD Average time to reoperation was 10 years The most common indications for reoperation were left AV valve regurgi-tation (67%), subaortic stenosis (25%), right AV valve regurgita-tion (22%), and residual ASD (11%) Reoperations included left

AV valve repair or replacement, subaortic resection, and right AV valve repair There was no difference in survival when comparing left AV valve repair (38 patients) with replacement (35 patients)

Complete Atrioventricular Septal Defect

Late reoperation following repair of complete AVSD occurs in approximately 20% of patients during the fi rst 20 years after surgical repair Lesions requiring reoperation include left and right AV valve regurgitation, left AV valve stenosis (native and prosthetic), and residual ASDs or VSDs

Residual left AV valve regurgitation may result from equate surgical reconstruction Intraoperative TEE helps guide the surgical repair thereby preventing patients from leaving the operating room with signifi cant residual left AV valve regur-gitation Right AV valve regurgitation requiring reoperation is rare after repair of complete AVSD It occurs in the presence

inad-of pulmonary hypertension or in association with tetralogy inad-of Fallot with right ventricular dysfunction and pulmonary valve regurgitation or stenosis Residual shunts are rare causes for late reoperation after initial repair of complete AVSD

Investigators at the Mayo Clinic recently assessed tion in 50 patients after repair of complete AVSD (70) The most common indication for reoperation was left AV valve regurgi-tation (41 patients) Similar to the PHN data, left AV valve stenosis was rare (1 patient) Half of this cohort underwent left

reopera-AV valve re-repair and the other half had valve replacement

Long-term survival was 86% at 15 years after the reoperation

POSTOPERATIVE ECHOCARDIOGRAPHIC ASSESSMENT

Echocardiographic assessment of the patient after repair of an AVSD includes evaluation of the morphology of the AV valves (Fig 29.26) and determination of right and left AV valve ste-nosis or regurgitation (71) A search for residual shunts should

be performed Doppler evaluation of the velocity profi les across

a ventricular level shunt and right AV valve regurgitation can

RA

RV

LVLA

LS

RA

RV

LV

LA

ana-tomic specimen of a patient with partial AVSD after patch closure of a primum ASD and repair of a cleft mitral valve The

patch (arrow) is attached to the right side

of the atrial septum and the right AV valve

to avoid damage to the conduction tissue

and left AV valve Right: corresponding

apical four-chamber echocardiograph

L, left; LA, left atrium; LV, left ventricle;

RA, right atrium; RV, right ventricle; S, superior

provide accurate determination of right ventricular systolic

pres-sure However, in the setting of a residual VSD, the VSD jet may

contaminate the right AV valve regurgitation signal and preclude

accurate quantifi cation of right ventricular systolic pressure In

that setting, the echocardiographer should use indirect techniques

such as assessment of ventricular septal fl attening or bowing, right

ventricular size and function, and Doppler interrogation of the

pulmonary regurgitation velocity waveforms to assess pulmonary

artery diastolic pressure Meticulous assessment of progressive

left AV valve regurgitation and progression of LVOT obstruction

must be performed during serial postoperative evaluations

THE ADULT WITH ATRIOVENTRICULAR SEPTAL

DEFECT

Previously Undiagnosed Adults with Atrioventricular

Septal Defect

When discovered in adulthood, patients with partial AVSD

will present with symptoms of exercise intolerance, dyspnea on

exertion, or palpitations from a new atrial arrhythmia These

patients may exhibit the typical physical exam fi ndings of an

ASD (systolic ejection murmur at the left upper sternal border,

widely split and fi xed second heart sound, and a diastolic

rum-ble along the left sternal border due to increased fl ow across

the right AV valve) Adults with previously undiagnosed partial

AVSD may come to diagnosis when a chest x-ray or

electrocar-diogram is performed for other reasons The chest x-ray may

demonstrate cardiomegaly, and the electrocardiogram often

shows left axis deviation A regurgitant S1-coincident

holosys-tolic murmur (due to the cleft in the anterior leafl et of the left AV

valve) may also prompt echocardiographic evaluation Left AV

valve stenosis is a rare fi nding in adults with unrepaired partial

AVSD If left AV stenosis is present, these patients usually have

a single papillary muscle and morphology of a parachute valve

Surgical repair of partial AVSD is recommended if discovered in

adulthood in the absence of signifi cant pulmonary hypertension

Echocardiography of adults with AVSD should be

per-formed in an imaging laboratory with extensive congenital

heart disease experience The role of cardiac catheterization

for some patients is to evaluate coronary artery anatomy or for

calculation of pulmonary vascular resistance One would

pre-fer the pulmonary arteriolar resistance (rPa) to be <7 units-m2

to safely consider repair of a partial AVSD in adulthood If the

rPa is elevated above this level, then provocative testing in the

catheterization laboratory with the use of pulmonary

vasoac-tive agents such as nitric oxide is indicated That said, patients

with rPa as high as 15 units-m2 have undergone successful

sur-gery for isolated ASD (72) In this select group of patients, one

would consider pre- and postoperative treatment with

pulmo-nary vasoactive agents such as bosentan, sildenafi l, or Flolan

and documentation via hemodynamic catheterization of a

sub-stantial improvement in rPa during this therapy In patients

older than age 40 years, regardless of symptoms, noninvasive

assessment of coronary artery disease typically is performed

prior to surgery Selective coronary angiography or CT

angi-ography may be indicated if noninvasive coronary assessment

is abnormal Primum ASDs are not amenable to closure with

commercially available transcatheter devices Minimally

inva-sive robotic techniques have been used to repair isolated mitral

valve clefts but, thus far, not in the setting of AVSD

Adults with Previously Repaired Atrioventricular

Septal Defect

Surgery for the repair of partial AVSD should be performed

by surgeons with training and expertise in congenital heart

disease (73) Surgical reoperation is recommended in adults with previously repaired AVSD for the following reasons:

1 Need for left AV valve repair or replacement due to symptomatic regurgitation or stenosis, arrhythmia, increase

in LV dimensions, or LV dysfunction

2 LVOT obstruction with a mean gradient >50 mm Hg

or a Doppler-derived maximum instantaneous gradient

>70 mm Hg LVOT obstruction with a mean gradient <50

mm Hg but associated with signifi cant mitral or aortic valve regurgitation

3 Residual or recurrent ASD or VSD with a signifi cant to-right shunt

left-Reoperation on the left AV valve does not necessarily dictate that valve replacement will be needed In the recent study from the Mayo Clinic, only half of the patients required left AV valve replacement at the time of the second operation (70) Interestingly, left AV valve replacement did not preclude further reoperation in these patients

Recommendations for Pregnancy

All women with a history of AVSD should be evaluated when

fi rst contemplating pregnancy to ensure that there are no nifi cant residual hemodynamic problems that may complicate their management Pregnancy usually is well tolerated by women who have had successful repair of AVSD In addition, for women with unrepaired partial AVSD, the left-to-right shunt and the left AV valve regurgitation usually are well tol-erated during pregnancy The data from the CARPREG study (74) and a more recent follow-up to that database (75) demon-strated that women with repaired and unrepaired left-to-right shunt lesions generally tolerated pregnancy well, except for a few cases of arrhythmia

sig-However, for women with pulmonary vascular tive disease and severe pulmonary artery hypertension (pul-monary artery systolic pressure > 60 mm Hg), pregnancy is not advised Adult patients with unrepaired complete AVSD typically have Eisenmenger physiology Fortunately with the advances in surgical techniques and improved outcomes over the last four decades, presentation in adulthood with unre-paired AVSD and Eisenmenger physiology is rare

obstruc-Patients who had repair of partial or complete AVSD require lifelong cardiology follow-up Preferably, this should

be at centers that specialize in the care of adults with genital heart disease At least 15% to 20% of these patients will come to reoperation because of progressive left AV valve regurgitation or LVOT obstruction LVOT obstruction may occur de novo even if the patient had undergone primary repair of partial AVSD as an adult (24)

con-Endocarditis prophylaxis is not generally advised based on the 2007 AHA guidelines for uncomplicated vaginal delivery

in woman with unrepaired partial AVSD For women who had repair of AVSD, one would expect to utilize endocar-ditis prophylaxis only in those who had valve replacement

Fetal echocardiography is recommended at approximately

20 weeks’ gestation due to the 3% to 5% recurrence risk of congenital heart disease in offspring when either parent had AVSD

CONCLUSIONS

The repair of AVSD has been one of the success stories in the

fi eld of congential heart surgery over the last four decades The pioneering work performed by Giancarlo Rastelli in the 1960s

is but one of these accomplishments In the modern era, adult survival with excellent quality of life is expected for children

born with AVSD However, 15% to 20% of these patients may

face reoperation in their lifetime All of these patients require

lifelong surveillance for development of LVOT obstruction

and left AV valve regurgitation

ACKNOWLEDGMENTS

The authors acknowledge the contributions of the former

authors of this chapter (Drs William Edwards, Francisco

Puga, and Robert Feldt) They participated in the landmark

research that formed the cornerstone of this chapter during

several editions of the textbook We also appreciate the

con-structive review of this chapter by Drs Bryan Cannon and

Patrick O’Leary

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