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

Diagnostic Imaging Cardiovascular

(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.

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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

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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.
J Thorac Imaging. 27(5):289-95, 2012
6. de Jong MC et al: Diagnostic performance of stress myocardial perfusion imaging for coronary artery disease: a
systematic review and meta-analysis. Eur Radiol. 22(9):1881-95, 2012

7. Fihn SD et al: 2012 ACCF/AHA/ACP/AATS/PCNA/SCAI/STS guideline for the diagnosis and management of patients
with stable ischemic heart disease: a report of the American College of Cardiology Foundation/American Heart
Association Task Force on Practice Guidelines, and the American College of Physicians, American Association for
Thoracic Surgery, Preventive Cardiovascular Nurses Association, Society for Cardiovascular Angiography and
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)
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o

o
o
o
o

Left circumflex (LCX)
 Proximal and mid/distal LCX (pCx, LCX)
 Obtuse marginal branches: OM1, OM2, OM3, etc.
Posterior lateral branch (PLB)

Posterior left ventricular (PLV) branch
Posterior descending artery (PDA)
Right coronary artery (RCA)
 Proximal, mid, and distal RCA (pRCA, mRCA, dRCA)
 Acute marginal (AM) branch
Sinoatrial node (SAN) branch
Atrioventricular node (AVN) branch

o
o
 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
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o
o
o

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





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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RCA






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
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






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
 Myocardial bridge
 Duplicated coronary artery
Anomalies of Termination
 Coronary-venous or coronary-cameral fistula
 Extracardiac termination
CARDIAC VEINS
 Anterior cardiac veins drain anterior right ventricular free wall, cross right atrioventricular groove, and enter
right atrium directly
 Coronary sinus, the largest cardiac vein at ˜ 14 mm diameter, enters right atrium near inferior vena cava
inflow
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.
185(4):1001-6, 2005
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Image Gallery
AORTIC ROOT AND CORONARY ARTERIES

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(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

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(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

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(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

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(Top) Left anterior oblique projection shows a right-dominant coronary system. (Middle) This is a curved maximumintensity projection (MIP) along the course of a dominant RCA. The view is known as the C view due to the
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.
P.8:10

LEFT CORONARY ARTERIES

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Diagnostic Imaging Cardiovascular

(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

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(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.
P.8:12

LEFT-, RIGHT-, AND CODOMINANT SYSTEMS

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Diagnostic Imaging Cardiovascular

(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.
P.8:13

CORONARY ARTERIES ORIGINS AND COURSE

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Diagnostic Imaging Cardiovascular

(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

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(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

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(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
Key Facts
Terminology
 Origin of left main or left anterior descending coronary artery from right sinus of Valsalva with course
between ascending aorta and pulmonary artery
o Associated with increased risk for myocardial ischemia or sudden cardiac death
Imaging
 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
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

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
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Diagnostic Imaging Cardiovascular
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
CLINICAL ISSUES
Presentation
 Most common signs/symptoms
o SCD, chest pain
 Other signs/symptoms
o Syncope, arrhythmia, and palpitations
Demographics
 Age
o Sudden death rarely occurs in patients over 35
 Epidemiology
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)
Imaging
 Anomalous origin of left coronary artery can be detected in invasive coronary angiography, but exact course
can be difficult to ascertain
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)
 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

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Diagnostic Imaging Cardiovascular

(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.
P.8:19

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

General Features
 Best diagnostic clue
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Diagnostic Imaging Cardiovascular
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)
Aortic Dissection
 In low-quality CTA of aorta, anomalous left coronary artery arising from right coronary cusp could mimic
appearance of dissection in aortic root
PATHOLOGY
General Features
 Not linked to sudden cardiac death or ischemia
CLINICAL ISSUES
Presentation
 Usually an incidental finding
 Some authors speculate on potential of spasm in anomalous coronary artery
 Coronary artery disease may affect anomalous coronary arteries
Demographics
 Age
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

 No treatment is required
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
2. Cheitlin MD et al: Congenital anomalies of coronary arteries: role in the pathogenesis of sudden cardiac death.
Herz. 34(4):268-79, 2009
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Diagnostic Imaging Cardiovascular
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
P.8:20

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
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Diagnostic Imaging Cardiovascular
branches.

(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.
P.8:21

(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.

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Diagnostic Imaging Cardiovascular

(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
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Diagnostic Imaging Cardiovascular



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
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