Ebook Feigenbaum’s echocardiography (8/E): Part 2

(BQ) Part 2 book Feigenbaum’s echocardiography has contents: Masses, tumors, and source of embolus, diseases of the aorta, congenital heart diseases, hypertrophic and other cardiomyopathies, dilated cardiomyopathies, stress echocardiography,.... and other contents.

Chapter 13

Infective Endocarditis

Infective endocarditis remains a challenging and often fatal condition Onereason for this is the difficulty of establishing an accurate diagnosis,particularly early in the course of the disease when proper management can

be lifesaving As therapeutic approaches have become more successful, theimportance of early and accurate diagnosis is self-evident Unfortunately, nosingle test or finding establishes the diagnosis in all cases Instead, aconstellation of findings that constitutes the diagnostic criteria continues toevolve

The central role that echocardiography plays in the diagnosis ofendocarditis began in the early 1970s with the echocardiographicdemonstration of a valvular vegetation by the M-mode technique With theadvent of two-dimensional and Doppler modalities, echocardiography hasbecome virtually indispensable in the diagnosis and management of thesepatients Today, echocardiographic findings are a central part of thediagnostic criteria for infective endocarditis

CLINICAL PERSPECTIVE

Despite improvements in therapy, infective endocarditis remains a potentiallylethal disease with an incidence of 4 to 8/100,000 patient-years Although theoverall incidence has not increased appreciably over time, several factorshave contributed to substantial recent changes in the epidemiology of the

disease For example, Staphylococcus aureus is now the most common cause

of endocarditis in most series, in part due to an aging population and theincreasing prevalence of intracardiac devices, including prosthetic valves,conduits, pacing wires, and indwelling catheters This has led to the concept

of “healthcare contact” as a recognized risk factor for the development ofinfective endocarditis Currently, approximately 25% of infectiveendocarditis cases in this country are attributable to a previous medical event

or procedure, such as implantation of a prosthetic valve or pacemaker Morerecently, the opioid epidemic that has plagued the United States has beenassociated with a striking increase in the incidence of drug-dependence–associated endocarditis Such patients appear to have a particularly poorprognosis, in part due to the likelihood of recurrent infection following valvereplacement therapy

Infective endocarditis is defined as a localized infection anywhere on theendocardium, including the chamber walls, vessels, and within congenitaldefects The vast majority of vegetations, however, occur on valve leaflets.Infection may also develop on any implanted or prosthetic material such asprosthetic valves, conduits, pacing electrodes, and catheters The process ofdeveloping endocarditis occurs in the setting of bacteremia or fungemia Theinitiating event usually requires the presence of a high-velocity jet, whichmay be due to a congenital anomaly such as a ventricular septal defect, aregurgitant valve, or a prosthetic valve It is thought that the jet interfereswith the protective endothelial surface, allowing the blood-borne pathogens

to adhere and coalesce As the nidus of infection organizes, masses ofmicroorganisms attract platelets, fibrin, and other materials and becomeadherent to the endothelial surface to form a vegetation The vegetation willgrow in size, either as a sessile clump or as a highly mobile and evenpedunculated mass with the potential for embolization As the hallmark ofendocarditis, the ability to detect the vegetation is the focal point ofdiagnosis This sequence of events offers a mechanism for development ofendocarditis in patients with underlying heart disease However, since asmany as 50% of patients who get endocarditis do not have lesions associatedwith a high-velocity jet, some other set of conditions must be operational inthese patients to explain the link between bacteremia and cardiacinvolvement

ECHOCARDIOGRAPHIC CHARACTERISTICS OF

VEGETATION

The versatility of echocardiography in the evaluation of endocarditis isillustrated in Table 13.1 Among its important functions is the identification

of underlying heart disease known to increase a patient’s risk of infection.Although the absence of underlying disease does not confer protectionagainst endocarditis, particular conditions, such as congenital heart disease,bicuspid aortic valve, and a myxomatous mitral valve, are known risk factors

At the same time, these conditions often confound the diagnosis ofendocarditis by creating abnormalities that mimic or concealechocardiographic evidence of infection

An essential first step in the echocardiographic evaluation is to search forevidence of acute ongoing infection Although there are severalmanifestations of endocarditis, including abscesses and fistulae, the mostcommon and direct evidence of infective endocarditis is the vegetation.Because a vegetation begins as a microscopic focus of infection andgradually grows into a conspicuous mass, its presence may or may not beevident on an imaging study Thus, echocardiography must be sensitiveenough to detect the vegetation and specific enough to distinguish it fromother echocardiographic abnormalities or artifacts As can be seen in Table13.2, certain echocardiographic features can be used to either increase ordecrease the probability that a visualized mass is due to endocarditis Avegetation is typically irregularly shaped, highly mobile, and attached to thefree edge of a valve leaflet They tend to develop on the upstream side of thevalve, that is, the ventricular side of the aortic valve and the atrial side of themitral valve (Fig 13.1) Vegetations may be sessile or pedunculated butusually have motion that is independent of the valve itself Figure 13.2 is anexample of endocarditis involving the tricuspid valve in a patient with ahistory of intravenous drug use The infectious process can be seen encasingthe valve leaflets and chordae Severe tricuspid regurgitation was present.Because vegetations often occur in the path of a high-velocity jet, theirmotion is frequently described as oscillating or fluttering The presence ofsignificant mobility, or oscillating motion, is a classic feature of mostvegetations In fact, the absence of mobility argues against the diagnosis andshould suggest the possibility of an alternative diagnosis, including a healedvegetation The shape and size of vegetations are quite variable and mayeither increase (due to progression of disease) or decrease (due to healing orembolization) over time (Fig 13.3) Fungal vegetations tend to be larger than

those caused by bacterial infections, and those involving the tricuspid valvetend to be larger compared with vegetations that affect the aortic or mitralvalve (Fig 13.4).

Table 13.1 COMPREHENSIVE ROLE OF ECHOCARDIOGRAPHY IN

PATIENTS WITH ENDOCARDITIS

Initial/early role:

Identifies predisposing heart disease

Early assessment in all cases of suspected IE

Detects complications

Assesses hemodynamic consequences

Serial evaluation (assesses efficacy of therapy)

Intraoperative assessment of extent of disease

Prognosis (risk of complications)

Establishes new baseline after therapy

Repeat/follow-up role:

TEE (after positive TTE) in patients at high risk for complications

Repeat TEE (after negative initial TEE) if clinical suspicion persists

Repeat TEE if suboptimal course during therapy (e.g., clinical deterioration, persistently positive blood cultures, worsening physical examination)

FIGURE 13.1 An example of a large, mobile vegetation on the aortic valve that fills the left ventricular outflow tract, seen from the parasternal long-axis (A) and the apical views (B)

Video 13-1a

Video 13-1b

Table 13.2 ECHOCARDIOGRAPHIC CRITERIA FOR DEFINING A

VEGETATION

Attached to valve, upstream side Nonvalvular location Irregular shape, amorphous Smooth surface or fibrillar

Associated tissue changes, valvular regurgitation Absence of regurgitation

Although typically attached to a valve, vegetations may also attach tochordae, chamber walls, or any foreign body, such as a pacemaker lead,indwelling catheter, or prosthetic valve sewing ring Figure 13.5 is anexample of endocarditis involving a porcine tricuspid valve as well as thepacing wire that extends through it The mass itself is typically homogeneouswith echogenicity similar to that of the myocardium However, vegetationscan occasionally be cystic or appear more dense and calcified The infectiousprocess often alters valve structure and function As a result, some degree ofregurgitation is associated with most cases of acute endocarditis In Figure13.6, a patient with an aortic valve vegetation is shown The involvement isextensive, and the valve is partially flail There is severe aortic regurgitation.

A patient with significant mitral regurgitation associated with an extensiveaortic valve vegetation is shown in Figure 13.7 Despite the presence ofsevere mitral regurgitation, neither a vegetation nor leaflet perforation weredemonstrated Figure 13.8 shows a patient with intravenous drug use whopresented early in the course of their endocarditis Small vegetations werenoted on the aortic, mitral, and tricuspid valves These were not fullyappreciated on transthoracic imaging

FIGURE 13.2 Extensive infection involving the right heart from a patient with a

history of intravenous drug use The vegetation involves the tricuspid valve

(arrow) and chordae (arrowhead)

Video 13-2

FIGURE 13.3 A: An example of disease progression from a patient with positive

blood cultures, mild aortic regurgitation, and a sclerotic aortic valve but no definite

vegetation (day 1) B: Two weeks later (day 14), a small vegetation is seen on the

valve (arrow) C: By day 22, the vegetation has increased in size (arrow) and

there is severe aortic regurgitation, despite antibiotic therapy

Video 13-3a

Video 13-3b

Video 13-3c

FIGURE 13.4 A very large fungal vegetation in an immunocompromised patient

is shown Extensive involvement of the mitral valve is demonstrated in the apical

long-axis (A) and four-chamber (C) views In B, the dimensions of the mass are

recorded

Video 13-4a

Video 13-4c

FIGURE 13.5 Transesophageal echocardiography shows a large mass (large

arrow) attached to a pacemaker lead, most likely an infected thrombus There are

also multiple small vegetations (small arrows) attached to the pacemaker wire in

the right atrium

Video 13-5

If the process results in destruction of underlying tissue leading to a flail

or perforated valve structure, the degree of regurgitation will be severe Forexample, if the infection leads to disruption of the aortic valve, severe aorticregurgitation will ensue This is demonstrated in Figure 13.9, taken from apatient with a severely disrupted aortic valve in the setting of staphylococcalendocarditis Figure 13.10 is an example of a small perforation of thenoncoronary cusp of the aortic valve due to infection Mild aorticregurgitation was present, but no definite vegetation was identified Another

example of a perforated valve due to S aureus infection is shown in Figure13.11 This patient had a large, highly mobile aortic valve vegetation Aperforation at the base of the anterior mitral leaflet is also demonstrated,along with severe mitral regurgitation Much less often, a large vegetationwill obstruct the valve orifice, leading to a functional form of valve stenosis(Fig 13.12)

Although most vegetations involve the valves, in some cases the infectionmay extend to other structures, such as the chamber wall Figure 13.13 shows

an unusual vegetation attached to the posterior wall of the aortic root.Multiple vegetations involving the aortic valve are also present

It should be emphasized that there is no single characteristic on theechocardiogram that will conclusively identify a mass as a vegetation Theability to detect a vegetation depends on vegetation size, location, thepresence of underlying heart disease, image quality, and instrument settings.All available echocardiographic windows should be used, and Doppler flow

mapping should be performed to identify any associated valvularregurgitation Often nonstandard imaging planes are needed for detection,especially for smaller vegetations Although masses as small as 2 mm havebeen reported, in most cases, a vegetation must be at least 3 to 6 mm in size

to be reliably seen Image quality will also influence our ability to visualizesmall structures As is discussed later, these are areas in which the advantages

of transesophageal echocardiography have been demonstrated

To avoid false-positive results, vegetations must be differentiated fromother echo-producing abnormalities, such as myxomatous processes,degenerative changes (including Lambl excrescences and calcification),tumors, thrombi, and imaging artifacts Figure 13.14 is taken from a patientwho was asymptomatic The large mitral valve mass could easily be mistakenfor a vegetation However, the absence of clinical signs of infection suggests

an alternative diagnosis In this case, the mass was a blood cyst Underlyingheart disease both obscures the presence of a vegetation and increases thelikelihood of false-positive findings through misinterpretation Figure 13.15

is from a patient with mitral valve prolapse who had fever due to a viralsyndrome The prolapsing scallop was incorrectly interpreted as a vegetation.The correct diagnosis was established based on absence of signs of infectionand direct comparison of the current echocardiogram to a prior study.Nonbacterial thrombotic endocarditis (Libman–Sacks) is also easily confusedwith infective endocarditis In Figure 13.16, two examples of nonbacterialthrombotic endocarditis are shown In both cases, nodular masses on present

on the free edge of the mitral leaflets that could easily be misinterpreted asbacterial vegetations Distinguishing between these two conditions can bevery difficult and must rely on clinical correlation

Thus, the accuracy of echocardiography is greater in patients withoutunderlying valve disease Furthermore, active vegetations must bedifferentiated from old or healed vegetations Some studies have suggestedthat vegetations tend to become smaller and more circumscribed andechogenic over time as part of the healing process (Fig 13.17) Although this

is generally true, a reduction in vegetation size might also suggestembolization Thus, distinguishing active from healed vegetations can neverrely on echocardiography alone but must take into account clinical factors

FIGURE 13.6 Transesophageal echocardiography demonstrates a vegetation

(arrow) on a partially disrupted aortic valve (A) In B, severe aortic regurgitation is

present (arrow)

Video 13-6a

Video 13-6b

FIGURE 13.7 Panels A and B demonstrate extensive and diffuse involvement of

the aortic valve (arrows) Although a mitral valve vegetation was not seen,

Doppler shows severe mitral regurgitation (arrows, C)

Video 13-7a

Video 13-7b

Video 13-7c

FIGURE 13.8 Multi-valve involvement of Staphylococcus aureus endocarditis is

shown Transesophageal echocardiography demonstrated small vegetations

(arrows) on the aortic (A), mitral (B), and tricuspid valves (C)

Video 13-8a

Video 13-8b

Video 13-8c

FIGURE 13.9 Another example of Staphylococcus aureus endocarditis is provided A shows a prolapsing or disrupted aortic cusp (arrow) In B, a

vegetation on the aortic valve is apparent (arrows) Color (C) and

continuous-wave Doppler (D) demonstrate severe aortic regurgitation Note the steep slope of

the spectral Doppler signal (arrows).

FIGURE 13.10 A transesophageal echocardiogram demonstrates a small perforation of the noncoronary cusp of the aortic valve A: Focal thickening is seen but no definite vegetation B: Color Doppler imaging demonstrates the jet

extending through the cusp (arrows) C: A short-axis view confirms the location of

the perforation (arrow)

Video 13-10

FIGURE 13.11 A large aortic valve vegetation (A, arrow) and a perforated anterior mitral valve leaflet (B, arrow) from a patient with intravenous drug use In

C, severe mitral regurgitation is demonstrated with color Doppler (arrows)

Video 13-11a

Video 13-11b

FIGURE 13.12 A: A large vegetation involving the anterior mitral leaflet (arrows).

B: Spectral Doppler imaging recorded a 10 mm Hg mean gradient across the

mitral valve.

FIGURE 13.13 A transesophageal echocardiogram demonstrates an aortic valve

vegetation (arrow) and a second vegetation adherent to the posterior aortic wall (arrowhead)

Video 13-13

DIAGNOSTIC ACCURACY OF ECHOCARDIOGRAPHY

Numerous clinical studies have tested the accuracy of echocardiography to

detect vegetations and other manifestations of acute endocarditis A limitation

of all these studies is the difficulty in defining the standard by which thediagnosis is established In most series, a clinical standard for diagnosis wasused that incorporated clinical findings, blood culture results, response totherapy, and outcome measures Although practical, this approach hasobvious limitations and very likely permitted the inclusion of some patientswho had bacteremia but never had endocarditis More rigorous diagnosticstandards that required pathologic and/or surgical confirmation must, bydefinition, exclude patients who have endocarditis but never come to eithersurgery nor autopsy As a result, only the “sickest of the sick” would beincluded in such series Finally, the recognition over time of the fundamentalinvolvement of echocardiography in establishing a diagnosis made itincreasingly difficult to “test the test.” That is, it becomes impossible toestablish the accuracy of a test (in this case, echocardiography) that isfundamentally involved in the definition of disease For all these reasons, theexact sensitivity and specificity of the various echocardiographic techniquesmust be interpreted in context Despite these limitations, the overall utility ofechocardiography as an integral part of the diagnostic algorithm is wellestablished

FIGURE 13.14 An example of a blood cyst (arrow) is demonstrated within the

mitral valve Diastolic (A) and systolic (B) frames are shown Such an appearance

could easily be confused with vegetation

Video 13-14

FIGURE 13.15 This echocardiogram was recorded from a patient with mitral

valve prolapse and significant mitral regurgitation The mitral valve was

myxomatous and partially flail A: The prolapsing valve is indicated by the arrows B: Severe mitral regurgitation is demonstrated (arrow) C: A transesophageal

echocardiogram demonstrates the prolapsing scallop (arrows) This could easily

be mistaken for a vegetation

Video 13-15

FIGURE 13.16 Two examples of nonbacterial thrombotic endocarditis are shown In A, from a patient with metastatic cancer, masses on the tips of the

mitral leaflets are noted (arrows) B is from a patient with systemic lupus, and

demonstrates a nodular mass on the free edge of the anterior mitral leaflet

(arrow)

Video 13-16b

Numerous studies have examined the accuracy of echocardiography forthe detection of manifestations of endocarditis The overall sensitivity of thetransthoracic technique to detect vegetations has generally ranged from 60%

to 70% However, most of these studies were performed over 20 years ago,using equipment that would be considered substandard by today’s criteria.Among the important determinants of sensitivity are vegetation size andimage quality Transthoracic echocardiography is also limited in its ability todetect some of the other manifestations of endocarditis, such as abscessformation It should be recognized that some patients with endocarditis maynot have vegetations, thereby accounting for some false-negative results.Establishing the specificity of the technique is more difficult Although thereported false-positive rate is quite low in most series, specificity will varywidely depending on the population being studied and the criteria used todefine disease As previously discussed, in the absence of clinical data,distinguishing active vegetations from healed vegetations, myxomatouschange, or tumors is nearly impossible As a result, echocardiography isinterpreted in context, thereby avoiding most false-positive results

Beginning in the mid-1980s, the potential advantages of transesophagealechocardiography in assessing patients with suspected endocarditis were firstrecognized In virtually every published series, the sensitivity oftransesophageal echocardiography is consistently higher than that of thetransthoracic technique The improved image quality and the closer proximitybetween transducer and valves account for much of this difference Smallervegetations, those associated with prosthetic valves, and those in locationsthat would be shadowed or obscured during transthoracic scanning are some

of the areas in which the transesophageal approach is superior

When the two echocardiographic techniques are compared in the samepatient population, the superior sensitivity of transesophageal imaging hasbeen a consistent finding (Fig 13.18) At the same time, many of thesecontemporary series have reported a sensitivity of transthoracicechocardiography that is lower than would be otherwise expected This may

be partly explained by the availability of transesophageal imaging If thetransthoracic examination is approached with less determination and rigor,small lesions may be missed, thereby contributing to the wide difference in

sensitivity between the two tests Although the superiority of thetransesophageal approach is beyond question, the magnitude of the difference(i.e., the surprisingly low sensitivity of transthoracic echocardiography) isnoteworthy Some of this may be explained on the basis of patient selectionthat included a greater percentage of individuals with a relatively low pretestlikelihood of disease Alternatively, the availability of transesophagealechocardiography may have indirectly contributed to the performance of amore cursory and less rigorous transthoracic study, followed by a thoroughand complete transesophageal examination An additional advantage oftransesophageal echocardiography is its ability to identify othermanifestations of endocarditis, such as annular abscesses and fistulae (Fig.13.19) Despite the relatively modest sensitivity of transthoracicechocardiography, a normal study in the presence of acceptable image qualityhas high negative predictive value and is strong evidence against

endocarditis, even in the setting of S aureus bacteremia.

FIGURE 13.17 An unusual vegetation involving the mitral valve.

Transesophageal two-chamber (A) and and four-chamber (B) views are shown.

The patient had developed endocarditis 1 year ago which was effectively treated with antibiotics The infection recurred with fever and positive blood cultures A

large, partially calcified mass (arrows) is seen on the mitral valve

Video 13-17a

Video 13-17b

The value of three-dimensional echocardiography in this area continues togrow Figure 13.20 is an example of a large vegetation on a bioprosthetictricuspid valve recorded with three-dimensional imaging In real-time, themass can be seen prolapsing into the right atrium during systole Figure 13.21

is an example of a perforated aortic valve, with severe aortic regurgitation,

clearly visualized with en face three-dimensional echocardiography In

theory, the ability of three-dimensional echocardiography to visualize anentire valve (rather than individual slices of the valve) should improvesensitivity by reducing false-negative results Unfortunately, most missedechocardiographic diagnoses are related to image quality, which would alsonegatively affect three-dimensional images That is, if a vegetation is missed

on two-dimensional imaging because of poor image quality, it may not beseen on three-dimensional imaging for the same reason.

FIGURE 13.18 Transthoracic and transesophageal echocardiograms from a patient with clinical signs of endocarditis The transthoracic study (A) revealed

moderate aortic regurgitation but no evidence of a vegetation With

transesophageal echocardiography, a perforated aortic cusp is demonstrated (B,

arrow), but no vegetation Moderate aortic regurgitation was present on color

Doppler (C, arrows).

Video 13-18

Image quality is generally not a problem with transesophagealechocardiography, but the high accuracy of two-dimensional transesophagealechocardiography will make it difficult for three-dimensional transesophagealechocardiography to demonstrate incremental value One potential advantage

of three-dimensional imaging is the opportunity to obtain a completevisualization of complex cases and provide true spatial assessment of theextent of disease Much more experience in this area can be expected over thenext several years

MULTIMODALITY IMAGING

Both MRI and CT have shown promise for the evaluation of patients withinfective endocarditis The spatial resolution and inherent three-dimensionalnature of these techniques account for their ability to visualize vegetationsand other manifestations of the disease (Fig 13.22) However, for theforeseeable future, echocardiography will remain the primary imagingmodality for most situations Situations where CT and MRI may play a roleinclude cases where there is uncertainty about the diagnosis (“possible”infective endocarditis by the Duke criteria) For example, when there isdiscrepancy between the echocardiographic and blood culture results, thenewer imaging modalities may help confirm or reject the diagnosis Theymay also be useful in the assessment of complex and/or advanced cases,involving multiple valves, or to detect cerebral embolic events, which areoften clinically silent

There is also considerable interest in the use of 18F-fluorodeoxyglucosePET/CT for the assessment of patients with endocarditis, especially involvingprosthetic valves and implanted devices such as pacemaker wires Thetechnique creates a whole body scan and provides a sensitive means tolocalize active areas of inflammation Like MRI, it may be useful to detectand localize peripheral embolization which can occur anywhere in the body

FIGURE 13.19 Transesophageal echocardiography from a patient with a mechanical aortic valve and positive blood cultures In A, a periaortic abscess is

indicated by the arrows In B, color Doppler demonstrates both tricuspid

regurgitation (small arrowheads) and a fistula between the aortic root and right atrium (large arrows)

Video 13-19a

Video 13-19b

Although there is considerable interest in these newer modalities for theassessment of patients with endocarditis, they should not be regarded as analternative to echocardiography and there are to date no clear guidelines ontheir appropriate use in this setting

EVOLUTION OF THE DIAGNOSTIC CRITERIA

The clinical diagnosis of infective endocarditis has always been challenging.Before the routine use of echocardiography, establishing the diagnosis ofendocarditis focused on evidence of ongoing infection within the bloodcoupled with clinical evidence of cardiac involvement In 1994, the DukeEndocarditis Service published new criteria for the diagnosis of endocarditisthat relied heavily on echocardiographic findings In this original study, 405cases were retrospectively reviewed and classified as definite, possible, orrejected on the basis of the presence or absence of major and minor criteria.When compared with previously used criteria, the newly proposed Dukecriteria classified significantly more cases as definite endocarditis Amongpathologically proven cases, the Duke criteria were significantly moresensitive (80%) compared with the von Reyn criteria (51%)

FIGURE 13.20 A three-dimensional transesophageal echocardiogram showing a

very large vegetation (arrows) on a bioprosthetic tricuspid valve, from the

perspective of the right atrium

Video 13-20

FIGURE 13.21 A perforation in a native aortic valve is demonstrated with

three-dimensional (A) and two-three-dimensional (B) echocardiography (see arrows).

Moderate aortic regurgitation is present (B, right)

Video 13-21b

Table 13.3 DEFINITION OF TERMS USED IN THE DUKE CRITERIA

Major criteria

(1) Blood culture positive for IE

Typical microorganisms consistent with IE from two separate blood cultures:

Viridans streptococci, Streptococcus bovis, HACEK group, Staphylococcus aureus; or

Community-acquired enterococci, in the absence of a primary focus; or

Microorganisms consistent with IE from persistently positive blood cultures, defined as follows:

At least two positive cultures of blood samples drawn >12 hr apart; or

All three or a majority of ≥4 separate cultures of blood (with first and last sample drawn at least 1 hr apart)

Single positive blood culture for Coxiella burnetii or antiphase I IgG antibody titer

>1:800

(2) Evidence of endocardial involvement

(3) Echocardiogram positive for IE, defined as follows:

Oscillating intracardiac mass on valve or supporting structures, in the path of regurgitant jets, or on implanted material in the absence of an alternative anatomic explanation; or Abscess; or

New partial dehiscence of prosthetic valve

(4) New valvular regurgitation (worsening or changing of pre-existing murmur not sufficient) Minor criteria

(1) Predisposition, predisposing heart condition, or injection drug use

(2) Fever, temperature >38°C

(3) Vascular phenomena, major arterial emboli, septic pulmonary infarcts, mycotic

aneurysm, intracranial hemorrhage, conjunctival hemorrhages, and Janeway lesions (4) Immunologic phenomena: glomerulonephritis, Osler nodes, Roth spots, and rheumatoid factor

(5) Microbiologic evidence: positive blood culture but does not meet a major criterion as noted abovea, or serologic evidence of active infection with organism consistent with IE (6) Echocardiographic minor criteria eliminated

aExcludes single positive cultures for coagulase-negative staphylococci and organisms that

do not cause endocarditis IE, infective endocarditis Adapted with permission from Li JS, Sexton DJ, Mick N, et al Proposed modifications to the Duke criteria for the diagnosis of

infective endocarditis Clin Infect Dis 2000;30(4):633–638 Copyright © 2000 by the

Infectious Diseases Society of America.

FIGURE 13.22 A cardiac CT image from the basal short-axis view from a patient

with a bioprosthetic aortic valve is shown A large perivalvular abscess is

indicated by the arrows.

Although the original criteria were generally accepted as an importantadvance in the diagnosis of endocarditis, there were limitations that wereaddressed in a subsequent publication (Li et al., 2000) Table 13.3 contains

the detailed description of terms used to define major and minor criteria,according to the updated modifications Using these terms, the diagnosis ofendocarditis can be confirmed or rejected as described in Table 13.4 On thebasis of the four major and five minor criteria, patients can be classified ashaving definite evidence of endocarditis, possible endocarditis, or thediagnosis can be rejected This approach has subsequently been validated innumerous studies involving a range of patient populations and endorsed bythe American College of Cardiology/American Heart Association practiceguidelines for the management of patients with valvular heart disease(Bonow et al., 2006).

The subsequent revision of the Duke criteria in 2000 included several

updates Most importantly, S aureus bacteremia was defined as a major

criterion, whether nosocomial or community acquired In recognition of thechallenges in identifying culture-negative endocarditis, Q-fever serology wasalso added as a major criterion However, the widespread use of antibiotics inthe community remains a source of false-negative blood cultures and willtherefore continue to be a challenge in the diagnosis of endocarditis Finally,the minor criterion of “echo consistent with IE but not meeting majorcriterion,” which had been invoked in cases of nonspecific valve thickening,was eliminated The enhancement in sensitivity provided by the revised Dukecriteria is achieved without a significant loss in specificity A key result wasthat many fewer cases of “possible” endocarditis occurred and moredefinitive diagnoses were achieved Although more difficult to test, mostseries have concluded that specificity is maintained and has been reported to

be as high as 99% This is primarily attributable to the inclusion of specificechocardiographic findings

The value of this approach is now well established In addition toproviding a more sensitive means to establish the diagnosis of endocarditis,the Duke criteria have emphasized the essential relationship between clinicaland echocardiographic findings Despite the well-recognized importance ofechocardiography in the evaluation of these patients, both false-positive andfalse-negative results may occur, underscoring the need to incorporate other(i.e., clinical) criteria Furthermore, the inclusion of echocardiographiccriteria has provided an impetus to standardize the various criteria used todefine the essential pathologic processes, including vegetations andabscesses These will be discussed subsequently

Table 13.4 Clinical Definition of Infective Endocarditis According to the

Duke Criteriaa

Definite infective endocarditis (clinical criteria)

(1) Two major criteria, or

(2) One major criterion and three minor criteria, or

(3) Five minor criteria

Possible infective endocarditis

(1) One major criterion and one minor criterion, or

(2) Three minor criteria

Rejected

(1) Firm alternate diagnosis explaining evidence of infective endocarditis, or

(2) Resolution of infective endocarditis syndrome with antibiotic therapy for ≤4 days, or (3) No pathologic evidence of infective endocarditis at surgery or autopsy, with antibiotic therapy for ≤4 days, or

(4) Does not meet criteria for possible infective endocarditis, as above

aSee Table 13.3 for definitions of major and minor criteria.

Adapted with permission from Li JS, Sexton DJ, Mick N, et al Proposed modifications to

the Duke criteria for the diagnosis of infective endocarditis Clin Infect Dis 2000;30(4):633–

638 Copyright © 2000 by the Infectious Diseases Society of America.

Figure 13.24 includes two examples of anterior mitral leaflet perforation due

to the destructive effects of the infectious process Note the difference in theseverity of regurgitation between the two cases An example of perforation ofthe aortic valve is provided in Figure 13.25 In this case, a mechanical mitralprosthesis is present and appears to function normally There is severe aorticregurgitation through a perforation in the aortic valve cusp, just above themitral sewing ring In Figure 13.26, severe tricuspid regurgitation resultedfrom damage to the valve despite successful antibiotic treatment of theinfection The very large regurgitant orifice that occurred as a result can beseen on the three-dimensional image

Table 13.5 COMPLICATIONS OF ENDOCARDITIS

Prosthetic valve dehiscence

Embolization

Pericardial effusion

An abscess is a localized pocket of infection (most often caused bystaphylococci or enterococci bacteria) that appears on ultrasound as either anechodense or an echolucent mass within the tissue The most commonlocation for an abscess is near the annulus of the aortic or mitral valve where

it can affect valve function and/or the conducting system of the heart Anexample of an aortic annulus (or ring) abscess is shown in Figure 13.27 Thisform of infection will sometimes develop in the absence of an associatedvegetation Although this example is clearly visualized on the transthoracicechocardiogram, most ring abscesses require transesophagealechocardiography for detection