Ebook Diagnostic imaging cardiovascular (2nd edition): Part 2

(BQ) Part 2 book Diagnostic imaging cardiovascular presents the following contents: Coronary artery disease, heart failure, electrophysiology, pulmonary vasculature, arterial, venous, extracranial cerebral arteries, renal vasculature, peripheral vasculature.

(Left) Cardiac CT was performed in an elderly woman presenting with anterior ST elevations and increased troponin, who refused cardiac cath and was hemodynamically stable Curved MPR image of the left anterior descending artery shows no evidence of coronary artery disease (Right) Two-chamber image during systole (same patient) shows severe hypokinesis of the LV apex with preserved contractility of the basal to mid LV segments, consistent with stress cardiomyopathy.

Section 8 - Coronary Artery Disease

Approach to Coronary Heart Disease

Introduction

Coronary artery disease is a leading cause of morbidity and mortality in Western countries The underlying pathology

is the development of atherosclerotic plaque in the intima of the coronary arteries While in most cases coronary atherosclerotic plaque will remain clinically silent, it can clinically manifest in a number of forms, such as stable coronary artery disease, acute coronary syndrome, heart failure, and sudden cardiac death

Clinical Manifestations of Coronary Artery Disease

Stable Coronary Artery Disease

In stable coronary artery disease, atherosclerotic plaque deposits in the coronary arteries lead to significant narrowing

of the coronary lumen with subsequent obstruction of the coronary blood stream This results in deficit in oxygen supply of the downstream myocardium during situations of increased demand (typically physical exercise) There is no close correlation between the anatomic degree of luminal obstruction and the extent of downstream ischemia at exercise, which depends on numerous factors These include the severity and length of the lesion, the amount of dependent myocardium, the resistance of the microvasculature, and the amount of collateral flow from other

coronary territories Revascularization serves to treat symptoms and improve prognosis and is usually recommended when the amount of ischemic myocardium exceeds 10% of the left ventricular mass

Acute Coronary Syndromes

Acute coronary syndromes have a mechanism that is different from stable coronary artery disease Typically, the index event is the rupture (most frequently) or erosion (less frequently) of the fibrous cap of an atherosclerotic plaque Material from within the plaque is exposed to the blood stream and leads to immediate thrombocyte

aggregation so that a thrombus forms on the surface of the ruptured plaque This thrombus can obstruct coronary blood flow, and depending on the degree of obstruction and downstream myocardial damage, the resulting clinical manifestation is either completely silent or symptomatic in the form of unstable angina, non-ST-elevation myocardial infarction, or ST-elevation myocardial infarction Treatment is usually emergent and includes both medication to counter thrombus aggregation and mechanical interventions to restore blood flow

Heart Failure

Acute coronary syndromes, including myocardial infarction, can remain clinically silent; therefore, substantial damage

to the myocardium can occur without the patient's noticing any chest pain episodes It is possible that heart failure with severely impaired left ventricular function is the first clinical manifestation of coronary artery disease, and patients with newly identified heart failure need to be worked up for the presence of coronary artery obstruction

Especially when left ventricular functional impairment is regional and not homogeneous, coronary artery disease should be strongly suspected

Sudden Cardiac Death

Sudden death is a possible first manifestation of coronary artery disease The underlying event is almost uniformly arrhythmia (Acute mechanical complications, such as myocardial rupture secondary to an acute myocardial

infarction, are possible but exceedingly infrequent) Arrhythmia leading to sudden death is usually ventricular

fibrillation It can either occur in the context of an acute coronary syndrome or be triggered by the sudden ischemia,

or it can occur in patients with heart failure due to old, often previously unknown, myocardial infarction

Diagnostic Strategies

Stable Coronary Artery Disease

Two diagnostic strategies exist for the diagnosis of stable coronary artery disease The underlying process is the presence of coronary stenoses that lead to myocardial ischemia Testing can aim either at identifying the ischemic myocardium under exercise or at the direct visualization of coronary artery stenoses

Since not all coronary stenoses cause ischemia, and since stenoses that do not cause ischemia do not require

revascularization, the usual preferred approach in patients with suspected stable coronary artery disease is the noninvasive identification of stress-induced myocardial ischemia It can be achieved with physical exercise (treadmill

or bicycle exercise) or pharmacologic stress (dipyridamole or dobutamine to increase contractility and myocardial oxygen demand or adenosine to achieve maximum vasodilation and “steal” effects) Commonly used tests include single-photon emission computed tomography (SPECT) and positron emission tomography (PET) myocardial perfusion and metabolic imaging, stress echocardiography, and stress magnetic resonance (MR) imaging

Another strategy is the direct visualization of coronary anatomy, as achieved by invasive coronary angiography or noninvasively by computed tomography (CT) coronary angiography It is limited by the fact that not all stenoses cause ischemia and hence require revascularization, and if a stenosis is detected, it may be difficult to determine whether it mandates treatment Invasive coronary angiography can be combined with measurement of the fractional flow reserve (FFR), which quantifies the relationship of mean arterial blood pressure before and after the stenosis during maximum vasodilation achieved by adenosine Currently, FFR is considered the gold standard to identify myocardial ischemia, and FFR values < 0.8 indicate that the respective lesion should be revascularized

Both testing approaches, ischemia and coronary anatomy, have certain limitations Ischemia testing has limited sensitivity and specificity Also, ischemia testing cannot identify coronary atherosclerotic plaque, which is

nonobstructive but might have implications for the future cardiovascular event risk Anatomic imaging, on the other hand, often identifies stenoses, and the treating physician (and patient) may feel compelled to perform

revascularization, even though not all stenoses cause relevant ischemia Additionally, invasive coronary angiography is associated with potential complications, and noninvasive coronary angiography by CT suffers from limited image quality, which, if misinterpreted, can lead to false-positive findings and unnecessary downstream

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testing Hence, the testing strategy has to take into account patient characteristics, pretest likelihood, and also local expertise with the various diagnostic tests The most frequently applied strategy encompasses initial testing for ischemia, followed, if positive, by anatomic imaging Coronary visualization by CT, however, may be a suitable

alternative to reliably rule out coronary stenoses, especially in patients who do not have a high likelihood of being diseased

Acute Coronary Syndromes

Acute coronary syndromes encompass a wide spectrum from unstable angina to ST-segment elevation myocardial infarction (STEMI) In STEMI, electrocardiography is the only test performed and leads to immediate coronary

catheterization In non-ST elevation acute coronary syndromes, further testing is usually performed before a decision about invasive angiography can be made It includes laboratory testing (troponin) complemented by

echocardiography to exclude differential diagnoses (acute pulmonary embolism, aortic dissection) and assess regional

as well as global left ventricular function It may also include testing for ischemia Coronary CT angiography plays an increasingly important role to rule out coronary artery disease, especially in patients who present with acute chest pain but have a relatively low pretest likelihood of acute coronary disease

Prevention

Prevention of the first acute coronary event is an important goal in coronary artery disease In individuals who are asymptomatic, the traditional risk factors, summarized, for example, in the Framingham Risk Score, are used to estimate the risk and the necessity of risk-lowering treatment by statins, aspirin, or antihypertensive medication It is increasingly recognized that imaging may also contribute to risk stratification (e.g., coronary calcium), but the role of imaging in primary prevention has not been definitely clarified It remains uncertain which individuals will benefit from imaging in the context of primary prevention

Summary

Numerous diagnostic strategies are available to address the various clinical manifestations of coronary artery disease

No single test is perfectly suited for all patients; the decision about the best testing strategy must take into account patient characteristics, such as the ability to breath-hold, obesity, arrhythmias, and metallic implants One must also consider the pretest likelihood of disease and local expertise with the various diagnostic tools

Selected References

1 Achenbach S et al: CV imaging: what was new in 2012? JACC Cardiovasc Imaging 6(6):714-34, 2013

2 Coelho-Filho OR et al: MR myocardial perfusion imaging Radiology 266(3):701-15, 2013

3 Dowsley T et al: The role of noninvasive imaging in coronary artery disease detection, prognosis, and clinical decision making Can J Cardiol 29(3):285-96, 2013

4 Nakazato R et al: Myocardial perfusion imaging with PET Imaging Med 5(1):35-46, 2013

5 Bamberg F et al: Imaging evaluation of acute chest pain: systematic review of evidence base and cost-effectiveness

Interventions, and Society of Thoracic Surgeons J Am Coll Cardiol 60(24):e44-e164, 2012

8 Joshi FR et al: Non-invasive imaging of atherosclerosis Eur Heart J Cardiovasc Imaging 13(3):205-18, 2012

9 Mc Ardle B et al: Nuclear perfusion imaging for functional evaluation of patients with known or suspected coronary artery disease: the future is now Future Cardiol 8(4):603-22, 2012

10 Parker MW et al: Diagnostic accuracy of cardiac positron emission tomography versus single photon emission computed tomography for coronary artery disease: a bivariate meta-analysis Circ Cardiovasc Imaging 5(6):700-7,

2012

11 Qaseem A et al: Diagnosis of stable ischemic heart disease: summary of a clinical practice guideline from the American College of Physicians/American College of Cardiology Foundation/American Heart Association/American Association for Thoracic Surgery/Preventive Cardiovascular Nurses Association/Society of Thoracic Surgeons Ann Intern Med 157(10):729-34, 2012

12 American College of Cardiology Foundation Appropriate Use Criteria Task Force et al:

ACCF/ASE/AHA/ASNC/HFSA/HRS/SCAI/SCCM/SCCT/SCMR 2011 Appropriate Use Criteria for Echocardiography A Report of the American College of Cardiology Foundation Appropriate Use Criteria Task Force, American Society of Echocardiography, American Heart Association, American Society of Nuclear Cardiology, Heart Failure Society of America, Heart Rhythm Society, Society for Cardiovascular Angiography and Interventions, Society of Critical Care Medicine, Society of Cardiovascular Computed Tomography, Society for Cardiovascular Magnetic Resonance American College of Chest Physicians J Am Soc Echocardiogr 24(3):229-67, 2011

13 Corti R et al: Imaging of atherosclerosis: magnetic resonance imaging Eur Heart J 32(14):1709-19b, 2011

14 Achenbach S et al: Imaging of coronary atherosclerosis by computed tomography Eur Heart J 31(12):1442-8, 2010

15 Achenbach S et al: The year in coronary artery disease JACC Cardiovasc Imaging 3(10):1065-77, 2010

16 Taylor AJ et al: ACCF/SCCT/ACR/AHA/ASE/ASNC/NASCI/SCAI/SCMR 2010 Appropriate Use Criteria for Cardiac Computed Tomography A Report of the American College of Cardiology Foundation Appropriate Use Criteria Task Force, the Society of Cardiovascular Computed Tomography, the American College of Radiology, the American Heart Association, the American Society of Echocardiography, the American Society of Nuclear Cardiology, the North American Society for Cardiovascular Imaging, the Society for Cardiovascular Angiography and Interventions, and the Society for Cardiovascular Magnetic Resonance Circulation 122(21):e525-55, 2010

17 Abdelmoneim SS et al: Quantitative myocardial contrast echocardiography during pharmacological stress for diagnosis of coronary artery disease: a systematic review and meta-analysis of diagnostic accuracy studies Eur J Echocardiogr 10(7):813-25, 2009

18 Schuijf JD et al: How to identify the asymptomatic high-risk patient? Curr Probl Cardiol 34(11):539-77, 2009

Coronary Anatomy

TERMINOLOGY

Abbreviations

 Coronary arteries and their branches

o Left main (LM) coronary artery

o Left anterior descending (LAD) coronary artery

 Proximal, mid, and distal LAD (pLAD, mLAD, dLAD)

 Diagonal branches: D1, D2, D3, etc

o Ramus intermedius (RI)

o Left circumflex (LCX)

 Proximal and mid/distal LCX (pCx, LCX)

 Obtuse marginal branches: OM1, OM2, OM3, etc

o Posterior lateral branch (PLB)

o Posterior left ventricular (PLV) branch

o Posterior descending artery (PDA)

o Right coronary artery (RCA)

 Proximal, mid, and distal RCA (pRCA, mRCA, dRCA)

 Acute marginal (AM) branch

o Sinoatrial node (SAN) branch

o Atrioventricular node (AVN) branch

 Grafts

o Saphenous vein graft (SVG)

o Coronary artery bypass graft (CABG)

o Left internal mammary artery (LIMA)

o Right internal mammary artery (RIMA)

 Alternative international nomenclature

o Ramus interventricularis anterior (RIVA) = LAD

o Ramus circumflexus (RCx) = LCX

o Ramus interventricularis posterior (RIVP, RIP) = PDA

o Ramus marginalis (RM or M) = OM

o Right posterolateral branch (RPL) = PLV branch from RCA

 Ramus posterolateralis dexter (RPD) = PLV branch from RCA; careful not to confuse with abbreviation for right posterior descending artery

o Right posterior descending artery (RPD) = PDA from RCA

Synonyms

 Epicardial arteries

IMAGING ANATOMY

Overview

 Major coronary arteries travel within epicardial fat of interventricular and atrioventricular grooves

 Considerable variability in size, number/location of branching vessels, and myocardial territories

ANATOMY

LM

 Arises from left coronary sinus

 Variable length but usually < 2 cm

 Courses behind right ventricular outflow tract, between pulmonary trunk and left atrium

 LM stenosis ≥ 50% is significant

o In contrast, stenosis of ≥70% is significant in all other segments

 Usually bifurcates into LAD and LCX

 Commonly trifurcates into LAD, LCX, and RI

o RI may follow the course of obtuse marginal or diagonal branch

 Rarely is absent with LM and LCX origins directly from left coronary sinus

LAD

 Continuation of LM

 Runs along anterior interventricular groove

 Occasionally dives into left ventricular myocardium, forming “myocardial bridge”

 Diagonal branches run diagonally over anterior left ventricular wall

o Numbered sequentially from proximal to distal (D1, D2, D3)

o Supply anterolateral wall

 Superior septal perforator branches extend into interventricular septum and anchor LAD to myocardium

o Septal perforators supply anterior 2/3 of septum

o 1st septal perforator commonly supplies His bundle and branches of AVN

o May form collaterals to PDA via inferior septal perforators

 Right ventricular branches are small but may form collaterals to RCA

o Circle of Vieussens = collateralization between branch of proximal LAD (left preinfundibular artery) and conus artery in setting of proximal LAD stenosis

 Distal LAD often wraps around apex and may form collaterals to distal PDA

 Segmentation

o Proximal LAD: End of LM to 1st large septal or D1 (1st diagonal), whichever is more proximal

o Mid LAD: End of proximal LAD to 1/2 the distance to the apex

 Some authors use origin of D2 (2nd diagonal) as distal landmark

o Distal LAD: End of mid LAD to end of LAD

LCX

 Arises from LM at nearly perpendicular angle

 Runs around mitral annulus in left atrioventricular groove

 Obtuse marginal branches (OM1, OM2, OM3)

 Nondominant LCX often terminates as OM branch

 Native LCX distal to OM branches is often diminutive

 If left dominant, branches into PLV and PDA

 LCX and OM branches supply lateral free wall and portion of anterolateral papillary muscle

 Segmentation

o Proximal LCX: End of LM to origin of OM1 (1st obtuse marginal branch)

o Mid and distal LCX: Distal to OM1 to end of LCX or PDA origin

RCA

 Arises from right coronary sinus

 Passes under right atrial appendage and descends into right anterior atrioventricular groove

 In 50%, 1st branch of RCA is conus branch

o Alternative origin from a separate ostium directly from right sinus of Valsalva

o Conus branch supplies right ventricular outflow tract

 In 60%, SAN is the next branch

o 40% take alternative supply from LCX atrial branches

 Acute marginal branches may be large and extend to apex

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 If right-dominant circulation, RCA bifurcates into PDA and PLV at cardiac crux

o When right dominant, described as right PDA (R-PDA); when left dominant, left PDA (L-PDA)

o PDA runs along posterior interventricular groove and supplies posterior 1/3 of inferior septum

o PLV courses cephalad and is usual source of AVN branch

 Segmentation

o Proximal RCA: Ostium to 1/2 the distance to acute margin of heart

o Mid RCA: End of proximal RCA to acute margin

o Distal RCA: Acute margin to PDA origin

Dominance

 Dominance is defined by supply of PDA and PLV

 There are right-, left-, and codominant coronary systems

 ˜ 85% are right dominant (RCA supplies PDA and PLV)

 8% are left dominant (LCX supplies PDA and PLV)

 7% are codominant (RCA and LCX share supply of PDA &/or PLV)

 Rare super-dominant RCA supplies territory of diminutive LCX

 Rare wrap-around LAD supplies PDA

CORONARY ARTERY SEGMENTATION

Society of Cardiovascular Computed Tomography Definitions

 Left main (LM) = ostium of LM to bifurcation to LAD/LCX or trifurcation to LAD/LCX/RI

 Proximal LAD (pLAD) = end of LM to 1st large septal or diagonal, whichever is more proximal

 Mid LAD (mLAD) = end of pLAD to 1/2 the distance to apex

 Distal LAD (dLAD) = end of mLAD to end of LAD

 Diagonal 1 (D1) = 1st diagonal branch of LAD

 Diagonal 2 (D2) = 2nd diagonal branch of LAD

 Ramus intermedius (RI) = vessel arising from LM between LAD and LCX in the case of trifurcation

 Proximal left circumflex (pCx) = end of LM to origin of 1st obtuse marginal

 Mid and distal left circumflex (LCX) = from 1st obtuse marginal to end of vessel or origin of L-PDA

 Obtuse marginal 1 (OM1) = 1st obtuse marginal branch of left circumflex

 PDA-LCX (L-PDA) = PDA from LCX

 PLB-L (L-PLB) = posterolateral branch from LCX

 Proximal RCA (pRCA) = ostium of RCA to 1/2 the distance to acute margin

 Mid RCA (mRCA) = end of pRCA to acute margin

 Distal RCA (dRCA) = acute margin to origin of PDA

 PDA-RCA (R-PDA) = PDA from RCA

 PLB-RCA (R-PLB) = posterolateral branch from RCA

 Alternative coronary artery segmentation

o Original 15-segment model published via American Heart Association committee by W Gerald Austen in 1975

o 28-segment model of Myocardial Infarction and Mortality in Coronary Artery Surgery Study

 Of note, some authors use 2nd diagonal branch (rather than 1/2 the distance from 1st branch) to apex as landmark dividing mid and distal LAD

NORMAL VARIANTS AND ANOMALIES

General Considerations

 Wide degree of variation with variable clinical significance

 Categorized as anomalies of origin, course, intrinsic anatomy, and termination

Anomalies of Origin and Course

 Absence of LM, with separate ostia of LAD and LCX directly from left coronary sinus

 High (above sinotubular junction) origin of coronary ostium

 Origin from opposite or rarely noncoronary cusp with anomalous course

o Benign variants have course either retroaortic or prepulmonic/anterior to right ventricular outflow tract

o Malignant variants have interarterial course between aorta and pulmonary artery

o Transseptal variant of malignant type, where vessel runs in myocardium just below interarterial space, is considered less malignant compared to other anomalies

 Anomalous left coronary artery from pulmonary artery (ALCAPA)

 Single coronary artery

Anomalies of Intrinsic Anatomy

 Congenital coronary ostial stenosis or atresia

 Congenital or acquired coronary ectasis or aneurysm

o There may be a complete or incomplete valve at its ostium (Thebesian valve)

 Middle cardiac vein runs in posterior interventricular groove and enters coronary sinus near its ostium

 Other tributaries to coronary sinus are posterior vein of left ventricle (drains inferior left ventricular wall), marginal veins, and great cardiac vein, which runs in left atrioventricular groove

 Anteriorly, great cardiac vein becomes anterior interventricular vein, which runs parallel to LAD and receives diagonal veins

RELATED REFERENCES

1 Raff GL et al: SCCT guidelines for the interpretation and reporting of coronary computed tomographic angiography

J Cardiovasc Comput Tomogr 3(2):122-36, 2009

2 Abbara S et al: Noninvasive evaluation of cardiac veins with 16-MDCT angiography AJR Am J Roentgenol

(Top) Volume-rendered image shows the aortic root and coronary arteries, oriented to depict the right coronary artery (Bottom) Volume-rendered image shows the aortic root and coronary arteries, oriented to depict the left coronary arteries.

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CORONARY ARTERY ORIGINS

(Top) 3D volume-rendered anteroposterior image shows the coronary artery origins The right ventricular outflow tract and atrial appendages have been excluded to depict the coronary origins (Middle) 3D volume-rendered

anteroposterior image shows the coronary artery origins The right ventricular outflow tract and atrial appendages have been excluded to depict the coronary origins (Bottom) 3D volume-rendered images show the diaphragmatic surface of the heart In this right-dominant coronary arterial system, the RCA continues as the PDA along the posterior interventricular groove

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LEFT CORONARY ARTERIES

(Top) Right anterior oblique caudal view of selective angiography shows a left-dominant coronary system (Bottom) 3D volume-rendered image shows the left coronary arteries.

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RIGHT CORONARY ARTERIES

(Top) Left anterior oblique projection shows a right-dominant coronary system (Middle) This is a curved intensity projection (MIP) along the course of a dominant RCA The view is known as the C view due to the

maximum-characteristic appearance of the RCA (Bottom) Curved MIP depicts the sinoatrial artery arising from the proximal RCA, the most common variant Less commonly, the sinoatrial artery arises from the LCX Rarely, it may arise directly from the right coronary sinus

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LEFT CORONARY ARTERIES

(Top) Image demonstrates the course and origin of the left circumflex coronary artery Left anterior oblique caudal

“spider” view depicts the left main, proximal LAD, and left circumflex coronary arteries (Middle) 3D volume-rendered image shows the left main coronary artery bifurcation The left atrial appendage has been excluded as the left main coronary artery would otherwise be hidden underneath (Bottom) 3D volume-rendered image shows the left main trifurcation into left anterior descending, ramus intermedius, and circumflex coronary arteries

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LEFT CORONARY ARTERIES

(Top) Axial maximum-intensity projection image demonstrates trifurcation of the left main coronary artery into left anterior descending, ramus intermedius, and left circumflex branches Here, the sinoatrial nodal artery arises from the proximal LCX, a normal variant (Middle) 3D volume rendering shows a left main coronary artery trifurcation The ramus intermedius most commonly courses laterally in a similar direction as the 1st diagonal but can also run parallel

to the obtuse marginal arteries (Bottom) 3D volume rendering shows an uncommon normal variant where the left main coronary artery is absent and the left anterior descending and circumflex arteries arise from separate ostia off the left coronary sinus

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LEFT-, RIGHT-, AND CODOMINANT SYSTEMS

(Top) 3D volume-rendered image shows the inferior surface of the heart in a right-dominant system Note the middle cardiac vein, which courses alongside the PDA in the posterior interventricular groove (Middle) Codominant coronary system is shown The PLV is supplied from the circumflex, and the PDA arises from the RCA (Bottom) Left-dominant coronary system is shown Both the PDA and the PLV arise from the LCX.

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CORONARY ARTERIES ORIGINS AND COURSE

(Top) Curved multiplanar reformation (MPR) shows the left anterior descending coronary artery, which arises from the left main coronary artery and travels along the anterior interventricular groove (Middle) Curved MPR shows the left circumflex coronary artery, which arises from the left main coronary artery and descends into the left

atrioventricular groove (Bottom) Curved MPR shows the right coronary artery, which arises from the right coronary sinus and passes under the right atrial appendage as it descends into right atrioventricular groove

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PERFUSION TERRITORIES

(Top) Graphic depicts the 17 left ventricular myocardial segments with corresponding color-coded coronary artery perfusion territories for a right-dominant coronary system (Bottom) Typically, the LAD supplies the anterior wall, anteroseptal wall, and apex The LCX supplies the lateral wall The RCA supplies the inferior and inferoseptal walls Considerable normal variation exists, and these perfusion territories should be considered as a guideline rather than a rule.

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18-SEGMENT CORONARY MODEL

(Top) Society of Cardiovascular Computed Tomography (SCCT) 18-segment coronary model, a modification of the original 1975 American Heart Association 15-segment model, is outlined (Bottom) Awareness of the differences between these 2 models is important to avoid confusion First, ramus intermedius and left posterolateral branches have been included as the 17th and 18th segments Second, the mid and distal LCX are considered a single segment Third, the boundary between the mid and distal LAD is defined as 1/2 the distance to the cardiac apex rather than the origin of the 2nd diagonal branch (Adapted from Raff GL et al: SCCT guidelines for the interpretation and reporting of coronary computed tomographic angiography J Cardiovasc Comput Tomogr 3[2]:122-36, 2009.)

Anomalous Left Coronary Artery, Malignant

 May be detected by very experienced operator in transesophageal echocardiography

 Can be suspected in invasive coronary angiography, but exact course is difficult to ascertain even in multiple projections

 Coronary CTA is gold standard for identification of anomalous coronary arteries and definition of their exact course, including their relationship to surrounding structures

 In experienced hands, contrast-enhanced MRA has high accuracy for identification of anomalous coronary arteries and their proximal course

Top Differential Diagnoses

 Aortic dissection

 Benign anomalous coronary artery

 Many other coronary anomalies that are not associated with increased risk for sudden death

Clinical Issues

 Most common signs/symptoms: Sudden cardiac death, chest pain

o Less frequent: Syncope, arrhythmia, and palpitations

 Sudden death rarely occurs over age of 35 and is often related to exercise

 Therapeutic options include stent placement and surgery

(Left) Graphic compares normal (top) and potentially malignant (bottom) courses of a left main (LM) coronary artery

If LM arises from the right sinus of Valsalva (or proximal right coronary artery), its course is considered potentially malignant and is associated with higher incidence of sudden cardiac death if LM follows an interarterial path between the aortic root and right ventricular outflow tract or pulmonary artery (Right) Axial coronary CTA shows an

interarterial (potentially malignant) LM course

(Left) Multiplanar reconstruction in coronal orientation (same patient) shows LM in cross section , positioned between the aorta and right ventricular outflow tract It is assumed that squeezing and stretching of LM can lead to ischemia and sudden death (Right) Invasive coronary angiography (right anterior oblique view) of the same patient does not allow assessment of the exact path of the anomalous LM

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TERMINOLOGY

Definitions

 Origin of left main (LM) or left anterior descending (LAD) coronary artery from right sinus of Valsalva with course between ascending aorta and pulmonary artery (PA)

 Associated with increased risk for myocardial ischemia or sudden cardiac death (SCD)

 Other potentially malignant anomalies include

o Origin of left coronary artery (LCA) from PA

 Extremely infrequent

 Usually detected in childhood

o Right coronary artery (RCA) arising from left sinus of Valsalva with course between ascending aorta and PA

 Substantially more frequent

 There is debate concerning its relevance IMAGING

General Features

 Best diagnostic clue

o LCA arising from right sinus of Valsalva or very proximal RCA and passing between ascending aorta and PA

 Best detected in cross-sectional imaging

o Ischemia in noninvasive testing can be an indication

Echocardiographic Findings

 Transesophageal echocardiography can identify ostia of coronary arteries, and a very experienced operator can characterize their proximal course in many cases

CT Findings

 ECG-gated contrast-enhanced coronary CT angiography (CTA)

o Gold standard for identification of anomalous coronary arteries and definition of their exact course, including their relationship to surrounding structures

MR Findings

 Contrast-enhanced coronary MR angiography (MRA)

o Highly accurate in identifying anomalous coronary arteries and their proximal course in experienced hands

o More difficult to perform and lower spatial resolution than coronary CT angiography

Angiographic Findings

 Invasive coronary angiography

o Even with multiple projections and insertion of PA catheter to delineate PA, it may not be possible

to identify the exact course of anomalous LCA DIFFERENTIAL DIAGNOSIS

Aortic Dissection

 In low-quality nongated CTA of aorta, anomalous LCA could mimic the appearance of dissection in aortic root (and vice versa)

Coronary Artery Stenosis

 Both coronary artery stenosis and anomalous coronary artery can cause ischemia and chest pain

Benign Anomalous Coronary Artery

 LM or LAD arising from right side with transseptal or subpulmonary course (through ventricular septum beneath right ventricular infundibulum)

 LM or LAD arising from right side; course anterior to PA

 LM or LAD with retroaortic course

 Any anomaly of left circumflex coronary artery

Anomalous Right Coronary Artery

 RCA arising from left sinus of Valsalva is a relatively frequent coronary anomaly

 Prevalence in patients who die suddenly is lower than that of malignant LCA anomaly

 Question whether or not to classify RCA arising from left sinus of Valsalva and passing between aorta and PA

as malignant anomaly is debated among experts

 Testing for ischemia (preferably with physical exercise) is a reasonable approach

PATHOLOGY

General Features

 Exact mechanism of sudden death is not known

o Most likely, ischemia and subsequent arrhythmias

o Sudden death is related to exercise in > 50% of cases

Gross Pathologic & Surgical Features

 Several anatomic features have been identified as particularly high risk when LM or LAD follows a course between aorta and PA: Slit-like aortic ostium, acute angle takeoff, and intramural aortic segment

o Malignant interarterial course of LCA is found in ˜ 1.3% of all coronary anomalies

o Most individuals with this anomaly never experience any clinical manifestation

Treatment

 Coronary bypass surgery, surgical unroofing, or reimplantation of coronaries above appropriate coronary sinus

 Excellent prognosis with early treatment

 Treatment is indicated in patients who have demonstrable ischemia or who have survived SCD

 Benefit is controversial in patients who are completely asymptomatic and have normal stress test results SELECTED REFERENCES

1 Peñalver JM et al: Anomalous aortic origin of coronary arteries from the opposite sinus: a critical appraisal of risk BMC Cardiovasc Disord 12:83, 2012

Anomalous Left Coronary Artery, Benign

Key Facts

Terminology

 Origin of left main coronary artery or left anterior descending coronary artery from right coronary cusp and a course

o Anterior to pulmonary artery (prepulmonary course)

o Behind aortic root (retroaortic course)

 May be detected by a very experienced operator in transesophageal echocardiography

Top Differential Diagnoses

 Occlusion of left main or left anterior descending coronary artery

 High-risk (malignant) anomalous left coronary artery

Clinical Issues

 Anomalous left coronary artery arising from right coronary cusp is present in ˜ 0.02-0.1% of population

 Usually an incidental finding

 Coronary artery disease may affect anomalous coronary arteries

 No treatment is required

(Left) Graphic shows normal left main (LM) coronary artery anatomy, potentially malignant interarterial course, and 3 benign variations of anomalous LM anatomy: Retroaortic course, anterior (a.k.a prepulmonary) course, and

transseptal (a.k.a subpulmonary) course (Right) CECT shows the retroaortic path of an anomalous LM that originates from the very proximal right coronary artery and courses dorsal to the aortic root toward the left This course

is benign and not associated with increased mortality

(Left) CECT in a patient who presents with acute chest pain shows anomalous LM with right-sided origin that passes anterior to the pulmonary artery This course is benign and carries no clinical relevance Note pulmonary

embolism (Right) CECT shows anomalous LM that originates from right sinus of Valsalva and courses through the septum, below the pulmonary artery, to the left This variant is similar to the potentially malignant

interarterial course but not associated with increased mortality

o Anterior to pulmonary artery (prepulmonary course)

o Behind aortic root (retroaortic course)

o Through interventricular septum and below right ventricular outflow tract (subpulmonary or transseptal course)

IMAGING

General Features

 Best diagnostic clue

o Left coronary artery arising from right sinus of Valsalva or very proximal right coronary artery and following prepulmonary, retroaortic, or transseptal course

Echocardiographic Findings

 Transesophageal echocardiography

CT Findings

 ECG-gated contrast-enhanced coronary CT angiography (CTA)

o Gold standard for identification of anomalous coronary arteries and definition of their exact course, including their relationship to surrounding structures

MR Findings

 Contrast-enhanced coronary MR angiography (MRA)

o High accuracy for identification of anomalous coronary arteries and their proximal course in

experienced hands

o More difficult to perform and lower spatial resolution than coronary CT angiography

Angiographic Findings

 Invasive coronary angiography

o Retroaortic course of anomalous coronary artery originating from right coronary cusp is usually straightforward to identify

o Origin of septal perforator branches from anomalous left main coronary artery makes subpulmonary (transseptal) course likely

o Prepulmonary and transseptal courses are difficult to differentiate from interarterial course, the latter of which is assumed to be high risk (malignant)

DIFFERENTIAL DIAGNOSIS

Occlusion of Left Main or Left Anterior Descending Coronary Artery

 Collaterals from right coronary artery (conus branch) may follow course very similar to prepulmonary course

of right-sided anomalous left coronary artery

High-Risk (Malignant) Anomalous Left Coronary Artery

 Left main coronary artery or left anterior descending coronary artery arising from right side with course between ascending aorta and pulmonary artery

 Risk of ischemia and sudden death is assumed to be associated with shear and squeezing of anomalous vessel and particularly pronounced when there is

o Slit-like aortic ostium

o Acute angle takeoff

o Intramural segment of the anomalous artery (within aortic wall)

 Usually an incidental finding

 Some authors speculate on potential of spasm in anomalous coronary artery

 Coronary artery disease may affect anomalous coronary arteries

Demographics

o Can incidentally be detected at any age

 Epidemiology

o Coronary anomalies are present in ˜ 0.3-1.6% of population

o Anomalous left coronary artery arising from right coronary cusp is present in ˜ 0.02-0.1% of

population Treatment

3 Frommelt PC: Congenital coronary artery abnormalities predisposing to sudden cardiac death Pacing Clin

Electrophysiol 32 Suppl 2:S63-6, 2009

4 Moustafa SE et al: Anomalous interarterial left coronary artery: an evidence based systematic overview Int J Cardiol 126(1):13-20, 2008

5 Angelini P: Coronary artery anomalies: an entity in search of an identity Circulation 115(10):1296-305, 2007

6 Jaggers J et al: Surgical therapy for anomalous aortic origin of the coronary arteries Semin Thorac Cardiovasc Surg Pediatr Card Surg Annu 122-7, 2005

7 Basso C et al: Clinical profile of congenital coronary artery anomalies with origin from the wrong aortic sinus leading

to sudden death in young competitive athletes J Am Coll Cardiol 35(6):1493-501, 2000

8 McConnell MV et al: Identification of anomalous coronary arteries and their anatomic course by magnetic

resonance coronary angiography Circulation 92(11):3158-62, 1995

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Image Gallery

(Left) Coronary CTA shows an anomalous LM with right-sided origin and a retroaortic course LM originates from the right sinus of Valsalva or right coronary artery (not seen here) and follows a course dorsal to the aortic root toward the left side (Right) 3D reconstruction of the same anomaly shows the retroaortic course of the LM The vessel then divides into a left circumflex and a left anterior descending coronary arteries, both of which follow a normal course

(Left) Coronary CTA shows an anomalous LM that originates from the right sinus of Valsalva or right coronary artery (not seen here) and then follows a course anterior to the pulmonary artery and toward the left side (Right) 3D reconstruction of the same anomaly shows the prepulmonary course of the LM The vessel then divides into a left anterior descending coronary artery and a circumflex coronary artery and also gives off diagonal and obtuse marginal

(Left) Coronary CTA shows an anomalous LM that originates from the right sinus of Valsalva and follows a course caudal to the pulmonary artery, through the interventricular septum and toward the left side (Right) 3D reconstruction of the same anomaly shows the LM surfacing from below the pulmonary artery The LM then divides into a left anterior descending and a left circumflex coronary arteries and also gives off an intermediate branch

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(Left) Coronary CT angiogram shows another example of a prepulmonary (or anterior) course of the LM coronary artery (Right) The corresponding 3D reconstruction clearly shows the course of the anomalous LM , which is anterior to the pulmonary artery, and absence of an artery originating from the left sinus of Valsalva This is a benign coronary artery variant

(Left) Invasive coronary angiography of an anomalous LM shows that the LM originates from the same ostium as the right coronary artery and follows a subpulmonary (or transseptal) course This can be identified because the

LM gives rise to a small septal branch (Right) An 8 mm thick maximum-intensity projection coronary CT

angiogram of the same patient clearly shows the subpulmonary course of the LM and also the small septal branch

(Left) Coronary CT angiography multiplanar reconstruction in coronal orientation in the same patient shows a cross section of the LM , which is embedded in the interventricular septum and gives rise to a small septal branch (Right) CECT shows another example of an anomalous LM with transseptal course The patient is 95 years old, and this fact indicates the benign nature of the anomaly

Anomalous LCX

Key Facts

Terminology

 Left circumflex (LCX) coronary artery originates from right sinus of Valsalva and courses posterior and inferior

to the noncoronary cusp toward left side

 No left main (LM) coronary artery segment is present

Imaging

 Abnormal vessel between noncoronary cusp and roof of atria

 Abnormal vessel arising from right sinus of Valsalva or right coronary artery (RCA) that courses posteriorly

 Originates from RCA, from common ostium with RCA, or directly from right sinus of Valsalva

 Cardiac gated multidetector CT is best imaging tool

 Cardiac MR in young patients and other patients in whom radiation is to be avoided or minimized

 Dot sign on invasive angiogram with aortic root injection in right anterior oblique view

o Dot represents contrast-filled LCX on end as it travels posterolaterally around aortic root

 Selective angiography of left LAD from left sinus shows absence of vessel in left atrioventricular groove Top Differential Diagnoses

 Anomalous RCA, benign variant

 Coronary fistula

 Sinoatrial node branch

Clinical Issues

 Anomalous LCX is most common variant of true coronary anomalies

 Usually benign incidental finding

Diagnostic Checklist

 Space between aortic noncoronary sinus and atria does not normally contain any vessels

(Left) Curved MPR CTA images show anomalous left circumflex (LCX) and left anterior descending (LAD) arteries with separate origins from right coronary cusp Right coronary artery (RCA) has normal origin LCX takes retroaortic course between the aorta and left atrium (Right) VR and oblique MPR images from CTA show anomalous LCX arising from right coronary cusp and having retroaortic course RCA arises from right coronary cusp LAD arises from left sinus of Valsalva Left main coronary artery is absent

(Left) Oblique graphic shows anomalous LCX arising from right sinus of Valsalva and coursing behind noncoronary sinus of Valsalva RCA is normal LAD arises directly from left sinus of Valsalva (Right) Right anterior oblique view of coronary catheter angiogram with selective catheterization shows an anomalous LCX with a separate origin from the right coronary cusp and with a retroaortic course

P.8:23

o Left anterior descending (LAD) coronary artery originates directly from left sinus of Valsalva

o No left main (LM) coronary artery segment is present

IMAGING

General Features

 Best diagnostic clue

o Abnormal vessel between noncoronary cusp and roof of atria

o No LCX branch off LM/LAD

o Abnormal vessel arising from right sinus of Valsalva or right coronary artery (RCA) that courses posteriorly

o Rarely, anomalous origin of LCX can be from pulmonary artery

 Mostly seen in childhood

 Associated with other major congenital cardiac defects, such as patent ductus arteriosus, aortic coarctation, and subaortic stenosis

 Best imaging tool

o Cardiac gated multidetector CT is best imaging tool

o Cardiac MR in young patients and other patients in whom radiation is to be avoided or minimized

 Protocol advice

o Cardiac gating is necessary to eliminate aortic pulsation artifact

CT Findings

 Cardiac gated CTA

o Considered gold standard as it demonstrates anomalous vessels at high spatial and contrast

resolution and depicts relationship with surrounding structures

o Anomalies with course outside the space between aorta and pulmonary artery are considered benign

Angiographic Findings

 Dot sign on invasive angiogram with aortic root injection in right anterior oblique view

o Dot represents contrast-filled LCX on end as it travels posterolateral around aortic root

 Selective angiography of left LAD from left sinus shows absence of vessel in left atrioventricular groove DIFFERENTIAL DIAGNOSIS

Anomalous RCA, Benign Variant

 Also runs posterior and inferior to noncoronary aortic sinus but in opposite direction

Coronary Fistula

 Usually multiple tortuous and enlarged feeders

Sinoatrial Node Branch

 Prominent sinoatrial nodal branch can be confused with anomalous LCX

 Best clue is identification of normal LCX branch off LM

 Epidemiology

o Primary congenital anomalies of coronary arteries can be found in 1-2% of general population

 Anomalous LCX is most common variant of true coronary anomalies

Natural History & Prognosis

 Usually benign incidental finding

 Volume-rendered CTA images are not useful unless atria are removed during segmentation

Image Interpretation Pearls

 Space between aortic noncoronary sinus and atria does not normally contain any vessels

o If a vessel in this space is detected, it is pathognomonic for anomalous coronary artery and

represents either anomalous LCX or anomalous RCA SELECTED REFERENCES

1 Dodd JD et al: Congenital anomalies of coronary artery origin in adults: 64-MDCT appearance AJR Am J Roentgenol 188(2):W138-46, 2007

2 Datta J et al: Anomalous coronary arteries in adults: depiction at multi-detector row CT angiography Radiology 235(3):812-8, 2005

Anomalous RCA

Key Facts

Imaging

 Malignant

o At risk of sudden cardiac death

o Variable origin of right coronary artery

o Passes between aorta and pulmonary artery

 Benign variants

o High take-off of coronary artery superior to right coronary cusp

o Rarely from left sinus of Valsalva coursing posterior and inferior to aortic root

 Cardiac multidetector CT is best imaging tool

 MR in children and young patients (no ionizing radiation)

Top Differential Diagnoses

 Other coronary anomalies

o Anomalous left main may have similar intraarterial course compared with malignant anomalous right coronary artery

 Coronary artery fistula

o Abnormal tortuous coronary artery but normal orgin from coronary ostium at sinus of Valsalva

o Usually drains into right-sided cardiac chambers or pulmonary artery

 Malignant variants may present with sudden cardiac death or arrhythmia

 Primary congenital coronary anomalies have incidence of 1-2%

(Left) Illustration (posterior view, patient's right is on right side of image) shows the relationship between an

anomalous RCA, aorta, and pulmonary artery In the malignant variant, the RCA is between the aorta and pulmonary artery In the rare benign variant, the RCA is posterior to the aorta (Right) Thick VR oblique cardiac CTA shows the aberrant origin of an RCA with an interarterial course The slit-like narrowing at the origin and the interarterial course are associated with increased risk for sudden death

(Left) Coronal oblique maximum-intensity projection image shows a high origin of the RCA The artery descends into the atrioventricular groove , which is its normal location (Right) 3D volume-rendered image shows the high origin of the RCA above the sinotubular junction The artery curves laterally before entering the atrioventricular groove This is not considered a malignant course and is almost always an asymptomatic finding

 Best diagnostic clue

o Absence of coronary artery ostium from right sinus of Valsalva, but RCA is present more distally

 RCA has to be traced back to its abnormal origin to differentiate from ostial RCA occlusion

 Location

o Origin of malignant anomalous RCA is variable

 Typically arises from left coronary cusp between origin of left main coronary artery and anterior commissure

 Rarely arises from left main

 May arise superior to sinotubular junction, either above left sinus of Valsalva or above junction of right and left sinuses of Valsalva

 Courses between anterior aspect of aortic root and posterior pulmonary artery wall

 Morphology

o May be oval in cross section, which has been suggested to be sign of compression; however, this view is controversial

o Slit-like origin is associated with intramural course (high-risk feature)

o If course crosses commissure, marsupialization may not be feasible

o Dominance of vessel may relate to risk

 Cardiac gated CTA

o ECG gating of CTA is necessary to allow depiction of coronary ostium and course of abnormal vessels

o Volume-rendered 3D images can be helpful to demonstrate spatial relationship of aortic root and anomalous vessel

MR Findings

 Coronary anomalies can be evaluated with MR

 Free of ionizing radiation

 2D or 3D coronary MRA can reliably assess anatomy of coronary artery

 ECG and respiratory gating are essential for motion-free imaging

DIFFERENTIAL DIAGNOSIS

Other Coronary Anomalies

 Anomalous left main may have similar intraarterial course compared with malignant anomalous RCA

Coronary Artery Fistula

 Abnormal tortuous coronary artery but normal orgin from coronary ostium at sinus of Valsalva

 Usually drains into right-sided cardiac chambers or pulmonary artery

PATHOLOGY

General Features

 Associated abnormalities

o Often isolated abnormality

Gross Pathologic & Surgical Features

 Slit-like ostium and intramural course of proximal malignant anomalous RCA is believed to have higher association with sudden cardiac death, especially if RCA is the dominant vessel

o Primary congenital coronary anomalies have incidence of 1-2%

Natural History & Prognosis

 Benign variant is typically clinically silent

 Malignant coronary artery anomalies are 2nd most common cause of sudden death in young athletes DIAGNOSTIC CHECKLIST

Image Interpretation Pearls

 Right sinus of Valsalva without coronary artery ostium

 Abnormal vessel course between aorta and pulmonary artery (malignant)

SELECTED REFERENCES

1 Camarda J et al: Coronary artery abnormalities and sudden cardiac death Pediatr Cardiol 33(3):434-8, 2012

2 Young PM et al: Cardiac imaging: Part 2, normal, variant, and anomalous configurations of the coronary vasculature AJR Am J Roentgenol 197(4):816-26, 2011

3 Clemente A et al: Anomalous origin of the coronary arteries in children: diagnostic role of three-dimensional coronary MR angiography Clin Imaging 34(5):337-43, 2010

4 Prakken NH et al: Screening for proximal coronary artery anomalies with 3-dimensional MR coronary angiography Int J Cardiovasc Imaging 26(6):701-10, 2010

5 Kelle S et al: Coronary MR imaging: lumen and wall Magn Reson Imaging Clin N Am 17(1):145-58, 2009

6 Mikolich JR: Cardiac magnetic resonance imaging and coronary computed tomography angiography in the diagnosis

of anomalous coronary artery J Am Coll Cardiol 53(5):456, 2009

Bland-White-Garland Syndrome

Key Facts

Terminology

 Anomalous origin of left main coronary artery from pulmonary artery (ALCAPA)

 Endothelial bud may persist on pulmonary sinus and attach to developing left main coronary artery

Imaging

 Left main coronary artery originates from pulmonary artery

 Best noninvasive test: Coronary CTA

o Cardiac MR is useful alternative

 Best invasive test: Coronary angiography

 Right heart catheterizations reveal left-to-right shunt in 75% of patients

o Average reported shunt: 1.5

 Number and extent of collaterals arising from right coronary artery are striking features of ALCAPA

o Collaterals are typically very large

Top Differential Diagnoses

o Establishment of dual coronary perfusion is preferred

o Direct reimplantation of anomalous coronary artery into aorta

o Intrapulmonary conduit from left coronary artery to aorta (Takeuchi repair)

 Adults

o Ligation of left coronary artery and bypass graft

 Many patients die from fatal ventricular dysrhythmias secondary to myocardial ischemia

(Left) Graphic shows a normal right coronary configuration from the right sinus of Valsalva and an anomalous origin of the left main coronary artery from the pulmonary artery (PA) (A = aorta; LAD = left anterior descending coronary

artery; LCX = left circumflex coronary artery; RCA = right coronary artery.) (Right) Coronary CTA 3D image shows a markedly dilated RCA and multiple collateral vessels as well as a dilated left main coronary artery (Courtesy

M Ichikawa, MD.)

(Left) Coronary CTA 3D image (same patient; cardiac chambers removed) shows anomalous left main coronary artery origin from PA Note multiple collateral vessels and dilated RCA Coronary arteries are dilated secondary to flow reversal from the systemic right to the low-pressure pulmonary system (Courtesy M Ichikawa, MD.) (Right) Coronary CTA 3D image (same patient) shows anomalous origin of left main coronary artery from PA Note dilated RCA arising normally from the aorta (Courtesy M Ichikawa, MD.)

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TERMINOLOGY

Definitions

 Anomalous origin of left main coronary artery from pulmonary artery (ALCAPA)

 Coronary arterial circulation is established by 45 days gestation in fetus

o Possible causes of anomalous left coronary artery from pulmonary artery

 Abnormal division of conotruncus

 Abnormal involution of endothelial buds on sinuses of Valsalva

 Endothelial bud may persist on pulmonary sinus and attach to developing left main coronary artery

IMAGING

General Features

 Best diagnostic clue

o Left main coronary artery originating from pulmonary artery

o Number and extent of collaterals arising from right coronary artery are striking features of ALCAPA

 Collaterals are typically very large Imaging Recommendations

 Best imaging tool

o Best noninvasive test: Coronary CTA

o Cardiac MR is useful alternative

 Does not currently have the spatial resolution of cardiac CTA

 Does allow depiction of perfusion deficits

 Late-enhancement gadolinium sequences allow detection of infarcted myocardium

o Best invasive test: Invasive coronary angiography

 Right heart catheterization reveals left-to-right shunt in 75% of patients

 Average reported shunt: 1.5:1

DIFFERENTIAL DIAGNOSIS

Coronary Fistula

 Normal origin of coronary artery

 Abnormal distal vessel drainage

o Drainage usually flows into right heart chambers or pulmonary artery

Other Coronary Artery Anomalies

 Anomalous right coronary artery from pulmonary artery (ARCAPA)

 Most common signs/symptoms

o Most adults will present with left ventricular dysfunction

 Other signs/symptoms

o Small number of patients are asymptomatic

o 96% have abnormal electrocardiogram

o Syncope and sudden death may occur due to ventricular arrhythmias

Natural History & Prognosis

 Degree of survival into adulthood depends on degree of collateralization from right coronary artery

 Average age of sudden death in untreated adult patients with anomalous left coronary artery from

pulmonary artery is 35 years

 Many patients die from fatal ventricular dysrhythmias secondary to myocardial ischemia

Treatment

 Infants

o Establishment of dual coronary perfusion is preferred

 Direct reimplantation of anomalous coronary artery into aorta

o Intrapulmonary conduit from left coronary artery to aorta (Takeuchi repair)

 Adults

o Ligation of left coronary artery and bypass graft

DIAGNOSTIC CHECKLIST

Image Interpretation Pearls

 Absence of left main coronary artery origin from left sinus of Valsalva differentiates anomalous left coronary artery from pulmonary artery from coronary fistula

SELECTED REFERENCES

1 Pursnani A et al: Coronary CTA assessment of coronary anomalies J Cardiovasc Comput Tomogr 6(1):48-59, 2012

2 Yau JM et al: Anomalous origin of the left coronary artery from the pulmonary artery in adults: a comprehensive review of 151 adult cases and a new diagnosis in a 53-year-old woman Clin Cardiol 34(4):204-10, 2011

3 Ichikawa M et al: Detection of Bland-White-Garland syndrome by multislice computed tomography in an elderly patient Int J Cardiol 114(2):288-90, 2007

4 Kim SY et al: Coronary artery anomalies: classification and ECG-gated multi-detector row CT findings with

angiographic correlation Radiographics 26(2):317-33; discussion 333-4, 2006

Imaging

 Cardiac gated CTA

o Absence of culprit atherosclerotic lesion

o May show subtle subendocardial perfusion defect

o May demonstrate underlying pathology (myxoma, left atrial appendage thrombus, etc.)

o May demonstrate patent foramen ovale (PFO), atrial septal defect (ASD), or other shunt responsible for paradoxical embolism

 MR demonstrates focal subendocardial delayed hyperenhancement in presence of

o PFO or ASD

o Left atrial appendage thrombus

o Left atrial myxoma or other mass

 SSFP cine

o Focal wall motion abnormality with otherwise maintained global left ventricular function

 T2-weighted FSE

o Edema adjacent to infarcted myocardium in the acute setting

o Usually larger area than infarct on LGE MR

 1st-pass perfusion

o Focal subendocardial perfusion defect matching delayed hyperenhancement

 Delayed enhancement

o Focal area of delayed hyperenhancement based on subendocardial myocardium

 Invasive coronary angiography usually demonstrates clean coronary arteries

Diagnostic Checklist

 Coronary embolus is diagnosis of exclusion

 Coronary artery disease with acute coronary syndrome and myocarditis need to be excluded

(Left) Short-axis LGE MR 2 days after sudden onset of acute chest pain shows focal subendocardial delayed

hyperenhancement , which is nearly transmural and represents a focal myocardial infarct in a subset of the RCA territory (PLV branch) No other foci of delayed enhancement are present (Right) Short-axis noncontrast T2WI FSE MR shows an area of T2 hyperintensity that is larger than the infarcted myocardium seen on LGE MR, indicating peri-infarct myocardial edema in a recent infarct

(Left) Oblique MPR of right coronary artery and portion of posterior left ventricular branch (PLV) shows absence

of any plaque or stenosis No culprit lesion (atherosclerotic plaque ± rupture) is identified (Right) Short-axis SSFP MR performed after contrast administration demonstrates high signal in the same location as above , which is due to a combination of hyperemic enhancement and edema Cine images showed focal akinesis in this segment, consistent with stunned myocardium

 Best diagnostic clue

o MR demonstrates focal subendocardial delayed hyperenhancement in presence of

 Patent foramen ovale (PFO) or atrial septal defect (ASD)

 Left atrial appendage (LAA) thrombus

 Left atrial (LA) myxoma or other mass

CT Findings

 Cardiac gated CTA

o Absence of culprit atherosclerotic lesion

 Often clean coronary arteries

o May show subtle subendocardial perfusion defect

o Regional akinesis (stunning) but maintained global function

o May demonstrate underlying pathology (myxoma, LAA thrombus, etc.)

o May demonstrate PFO, ASD, or other shunt responsible for paradoxical embolism

MR Findings

 SSFP white blood cine

o Focal wall motion abnormality with otherwise maintained global left ventricular (LV) function

o If performed after gadolinium administration, may demonstrate area of hyperenhancement

o May demonstrate edema

 T2-weighted FSE

o Edema adjacent to infarcted myocardium in the acute setting

 Usually larger area than infarct on LGE MR

 Invasive coronary angiography usually demonstrates clean coronary arteries

o May demonstrate distal intraluminal filling defect

Imaging Recommendations

 Best imaging tool

o Cardiac MR is best modality to suggest diagnosis

 Protocol advice

o Include T1 pre- and post-contrast images to exclude myocarditis

DIFFERENTIAL DIAGNOSIS

Acute Myocardial Infarction Due to Atherosclerotic Coronary Artery Disease

 Associated coronary artery disease

Myocarditis

 Clean coronary arteries but elevated cardiac markers

 Linear mid-myocardial or subepicardial hyperenhancement

 Increased relative global enhancement (myocardium vs skeletal muscle)

PATHOLOGY

General Features

 Etiology

o Dislodged thrombus from deep venous thrombosis (DVT) or fat from long bone after fracture

o Left atrial myxoma or other neoplasm

o Plaque or cholesterol dislodged during coronary angioplasty

 Associated abnormalities

o DVT, left atrial appendix thrombus, LA myxoma or other tumor

o Septal pouch in left atrium

Gross Pathologic & Surgical Features

 Usually small focal myocardial necrosis based on subendocardial myocardium

CLINICAL ISSUES

Presentation

 Most common signs/symptoms

o Usually atypical presentation due to small area of infarction

o Chest pain; pain in chin, left arm, or epigastrium

 Treat underlying cause

o ASD closure device, resection of myxoma, treat DVT

DIAGNOSTIC CHECKLIST

Consider

 Coronary embolus is diagnosis of exclusion

o Coronary artery disease with acute coronary syndrome and myocarditis need to be excluded SELECTED REFERENCES

1 Breithardt OA et al: A coronary embolus originating from the interatrial septum Eur Heart J 27(23):2745, 2006

2 Duman D et al: Paradoxical mesentery embolism and silent myocardial infarction in primary antiphospholipid syndrome: a case report Heart Surg Forum 9(2):E592-4, 2006

3 Rana O et al: Images in clinical medicine Cholesterol emboli after coronary angioplasty N Engl J Med

354(12):1294, 2006

Coronary Artery Aneurysm

Key Facts

Terminology

 Coronary artery diameter > 1.5× normal adjacent segments, involving < 50% of vessel

 Coronary artery ectasia: Diffuse coronary artery dilatation

Imaging

 Coronary CTA

o Evaluation of coronary aneurysm morphology, thrombosis, dissection

o Calcification frequently present in atherosclerosis

o Size underestimation with mural thrombus or dissection

o Preferred modality when surveillance required

o Calcification difficult to detect

o Stents and clips may degrade image quality

 Angiography: May underestimate size if mural thrombus or dissection is present

Top Differential Diagnoses

 Coronary fistula

 Coronary pseudoaneurysm

Pathology

 Atherosclerosis is most common cause in USA

o Right coronary artery is typically affected

 Kawasaki disease is most common cause worldwide

o Left main artery is most commonly affected

Clinical Issues

 Most patients are asymptomatic

 May present with acute coronary syndrome and heart failure

 Treatment: Anticoagulants, antiplatelets, surgery

Diagnostic Checklist

 Consider coronary artery aneurysm in patients < 20 years old with angina or acute myocardial infarction

(Left) Axial coronary CTA of a 19-year-old female with leukemia and acute chest pain shows a focal right coronary artery aneurysm and associated hemopericardium (Right) Oblique CTA of the same patient shows focal disruption of the aneurysm, which had enlarged over the previous 2 days Aneurysm rupture is a rare complication

of coronary artery aneurysm Aneurysm enlargement and rupture are indications for intervention This patient was treated with a covered coronary stent

(Left) Axial coronary CTA of a 26-year-old woman with Kawasaki disease shows dilatation of the right and left main coronary arteries Note peripheral calcification of the enlarged left main coronary artery (Right) 3D volume-rendered image from a coronary CTA of a 42-year-old man with Kawasaki disease shows dilatation of the left anterior descending and left circumflex coronary arteries Coronary artery aneurysms occur in 15-25% of untreated patients with Kawasaki disease.

 Best diagnostic clue

o Dilatation of coronary artery

 Morphology

o Fusiform or saccular dilatation

 May exhibit thrombus or dissection

o Coronary artery ectasia refers to diffuse dilation

CT Findings

 Cardiac gated CTA

o Evaluation of coronary aneurysm morphology, thrombosis, dissection

o Calcification is frequently present in atherosclerosis

MR Findings

 Available coronary angiography sequences

o Lumen is dark on double IR-FSE

o Lumen is bright on GRE or b-SSFP in absence of thrombus

 May be preferred modality when surveillance required

 Calcification is difficult to detect

 Stents and clips may degrade image quality

Echocardiographic Findings

 Echocardiogram

o Aneurysm detection in proximal coronary arteries

Angiographic Findings

 Fusiform and saccular dilatation of coronary arteries

 May underestimate size if mural thrombus or dissection is present

Imaging Recommendations

 Best imaging tool

o Gated coronary CTA is imaging modality of choice

DIFFERENTIAL DIAGNOSIS

Coronary Fistula

 Dilated vessel associated with fistula

 Coronary ectasia proximal to fistula if large shunt or steal physiology is present

o Atherosclerosis is most common cause in USA

 Right coronary artery is most commonly affected, followed by left anterior descending, left circumflex, and left main coronary arteries

o Kawasaki disease is most common cause worldwide

 Coronary artery aneurysm develops in 15-25% of untreated affected children

 May regress with treatment

 Left main coronary artery most commonly involved

o Takayasu arteritis (12% have coronary involvement)

o Connective tissue disease (systemic lupus erythematosus, Marfan, Behçet)

o Other: Congenital, trauma, catheter-based intervention, mycotic emboli, cocaine use

Staging, Grading, & Classification

 True aneurysm walls consist of all 3 vessel wall layers

 Pseudoaneurysms have ≤ 2 intact walls

 > 20 mm diameter in adults is considered “giant”

Gross Pathologic & Surgical Features

 Dilatation of coronary artery, may contain thrombus

Microscopic Features

 Atherosclerotic coronary aneurysms may exhibit thinning or destruction of media

CLINICAL ISSUES

Presentation

 Most common signs/symptoms

o Most patients are asymptomatic

o Acute coronary syndrome and heart failure may be caused by aneurysm or concurrent disease

o Present in ˜ 5% of angiograms, 1.5% of necropsies

Natural History & Prognosis

 Related to severity of concomitant obstructive disease in patients with atherosclerosis

 Rupture has been reported but is rare

Treatment

 Anticoagulants, antiplatelet therapy

 Surgical intervention if enlargement, embolization, or obstruction

o Bypass and exclusion of aneurysm

o Covered stent graft

 Kawasaki disease is typically treated with high-dose intravenous γ-globulin and aspirin

DIAGNOSTIC CHECKLIST

Consider

 Coronary artery aneurysm in patients < 20 years old presenting with angina or acute myocardial infarction SELECTED REFERENCES

1 Pursnani A et al: Coronary CTA assessment of coronary anomalies J Cardiovasc Comput Tomogr 6(1):48-59, 2012

2 Díaz-Zamudio M et al: Coronary artery aneurysms and ectasia: role of coronary CT angiography Radiographics 29(7):1939-54, 2009

 ECG-gated nonenhanced cardiac CT is used to detect and quantify coronary calcium

 By convention, threshold for identification of calcium is 130 HU at a tube potential of 120 kV

 Identification of ≥ 3 contiguous pixels with attenuation > 130 HU in wall of a coronary artery is defined as calcified coronary lesions

 Agatston score, determined from plaque area and coefficient that depends on peak CT attenuation, is widely used to quantify coronary calcium

Top Differential Diagnoses

 Coronary artery stent

 Mitral annular calcification

 Aortic wall calcification

Clinical Issues

 In asymptomatic individuals, presence and extent of coronary calcium correlate to risk of future

cardiovascular events

o Coronary calcium is therefore part of some risk assessment algorithms used to select candidates for cholesterol-lowering drug therapy

 Interscan variability is high, especially for low scores

 Repeat testing is not recommended

(Left) Nonenhanced CT is used for visualizing coronary calcification By international standard, 120 kV are used for acquisition, and the reconstructed slice thickness is 3 mm Two small calcifications of the proximal left anterior descending coronary artery are detectable (Right) Coronary calcium is also visible on contrast-enhanced coronary CT angiography Here, a small calcification of the proximal left anterior descending coronary artery is present

(Left) In a fluoroscopic frame (left), calcification is detectable as a grayish shadow After injection of contrast agent (right), the calcium deposit next to the contrast-filled lumen is better visualized (Right) Intravascular ultrasound (IVUS) is the most sensitive in vivo method for identifying coronary calcifications They appear bright and cause shadowing The less intensive shadowing is caused by the intracoronary wire that is used to guide the IVUS catheter (present in all IVUS images)

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TERMINOLOGY

Definitions

 Deposition of calcium hydroxyapatite in coronary arteries

o Coronary calcium is always in intima and hence associated with coronary atherosclerotic plaque

o Possible exception: Patients with renal failure may develop medial calcification

 Nonenhanced CT imaging and quantitative software are used to determine coronary artery calcium score (CACS, Agatston score)

o By convention, threshold for identification of calcium is 130 HU at tube potential of 120 kVp

o Agatston score is widely used to quantify coronary calcium

 Requires reconstruction of 3 mm thick slices

 Lesions must have area of ≥ 3 contiguous pixels > 130 HU

 For each lesion, a cofactor is derived from its peak attenuation

 Cofactor 1 for 131-200 HU

 Cofactor 2 for 201-300 HU

 Cofactor 3 for peak 301-400 HU

 Cofactor 4 for peak 401+ HU

 Agatston score for each plaque in each slice is product of plaque area and cofactor

 Scores for all lesions in all slices are summarized to obtain per-vessel and per-patient Agatston scores

o Alternative methods for scoring include calcified plaque volume and calcified mass (which requires a phantom for reference)

o Vast majority of published scientific literature uses Agatston score

 Contrast-enhanced CT angiography

o Calcified plaques can also be detected in contrast-enhanced coronary CT angiography

o Very small calcifications may be missed due to CT attenuation similar to contrast-enhanced lumen

o Higher spatial resolution and overlap of CT attenuation values with contrast-enhanced lumen make use of Agatston score impossible in CT angiography

Imaging Recommendations

 Best imaging tool

o Multidetector-row CT

 Best diagnostic tool

o Nonenhanced, ECG-gated CT imaging

o Identification of ≥ 3 contiguous pixels with attenuation > 130 HU in wall of a coronary artery is defined as coronary calcium

DIFFERENTIAL DIAGNOSIS

Coronary Artery Stent

 On nonenhanced CT, a coronary stent can have similar appearance to coronary calcium

Mitral Annular Calcification

 Corresponds to location of mitral valve annulus

 Can be misinterpreted as left circumflex coronary artery calcification

Calcification of Aortic Wall

 Must avoid aortic wall calcification and ostial coronary calcium in calculation of CACS

Calcification of Old Myocardial Infarction

 Calcium found at advanced stage of atherosclerotic plaque development

o Calcium hydroxyapatite deposition involves active inflammation and processes similar to

osteogenesis

 Amount of calcified plaque roughly correlates to total amount of plaque

o Calcified plaque represents ˜ 20% of total plaque burden

 Coronary atherosclerotic plaque and even stenosis can be present even when calcium is absent

o Especially in patients who are

 Young