Coronary Artery Anomaliesof Origin and Course

The Most Common Coronary Anomalies

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  Left circumflex artery (LCX) arising from:

  • A separate ostia in the right sinus of Valsalva (69%)

  • LCX arising from the proximal right coronary artery (RCA; 31%)

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  Single coronary artery from the left sinus of Valsalva

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  Both coronary arteries arising from the right sinus of Valsalva

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  Left anterior descending artery (LAD) arising from the right sinus of Valsalva

Overall, the most common course of an anomalous artery is anterior or posterior to the great vessels, rather than intra-arterial, although nearly half of anomalous right coronary arteries have an intra-arterial course.

Terminology of Anomalies of Course

Anomalies of course may be described using the following terminology :

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  Type A: A nterior to the pulmonary artery, or pre-pulmonic course

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  Type B: B etween the aorta and pulmonary artery, or intra-arterial course

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  Type C: Through the c rista supraventricularis; also known as intraseptal, septal, subpulmonary course, or “tunneled”

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  Through the right ventricular (RV) infundubulum

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  Type D: D orsal pathway, or posterior” or retro-aortic course

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  Mixed

Torres et al. reported on 6000 consecutive cardiac CT (CCT) cases. Of 15 anomalous left coronary arteries arising from the right sinus of Valsalva and anomalous right coronary arteries arising from the left sinus of Valsalva, and coursing between the aorta and the pulmonary artery, the following patterns were seen: two were intra-arterial, four were intraseptal, eight had a mixed intra-arterial/intraseptal course, and one coursed through the right ventricular infundibulum. These findings challenge the traditional classification of the course of anomalous coronary arteries ( Fig. 9-1 ).

Incidence of Coronary Artery Anomalies

The true incidence of coronary anomalies is unknown; furthermore, despite a considerable number of papers describing coronary anomalies in depth, the true range of anomalies is incompletely mapped out. The reported incidence varies depending on the definition, the methodology used, and the patient profile (the pretest probability) assessed.

Determining the Clinical Relevance of Coronary Artery Anomalies

Most patients with coronary anomalies are asymptomatic throughout life, and most coronary anomaly patterns are believed to be benign (∼70–80%). Only about 20% to 30% of those recognized are considered potentially serious or lethal.

Coronary anomalies that do not commonly have clinical risk include those with high ostia, multiple ostia, or “split” courses, and those that do not plausibly impair coronary flow (i.e., do not have congenital stenosis or atresia, do not have a tangential take-off, do not have an intramural course, do not have an intra-arterial course) or supply with desaturated blood (i.e., do not arise from the pulmonary artery).

Establishing that a coronary anomaly is the cause of clinical symptoms or presentation requires that alternative explanations and plausible associations be excluded.

Occasional clinical manifestations include sudden death, ventricular fibrillation, myocardial infarction, cardiomyopathy, syncope, and chest pain.

Major clinical presentations appear to be more common with certain patterns of anomalies and with certain patient groups. Among high school athletes who experience sudden nontraumatic death, coronary anomalies are the second most common cause of death. Similarly, it has been reported that coronary artery anomalies may be the second most common cause of sudden death in competitive athletes less than 35 years of age (second only to hypertrophic cardiomyopathy). ^, In an autopsy series of military recruits, coronary artery anomalies were the most common cause of sudden nontraumatic death.

A given anomaly, though, may have disparate clinical profiles: it may be found in a young patient who is symptomatic and who is being assessed for the these symptoms, or it may be “incidentally” detected well into adult life when angiography for coronary artery disease (CAD) evaluation or CT scanning for other purposes is performed. Many notable cases have been documented where, for example, longevity was achieved by a patient who had an anomaly generally thought to be “potentially serious” or “lethal.”

The many permutations of anomalies lessen their overall clinical relevance; however, several recurrent themes have emerged. Among young athletes with anomalous coronary arteries who experience sudden death, over three quarters of the anomalies have an intra-arterial course. The intra-arterial course of the left main coronary artery (LMCA) is associated with higher risk than a retro-aortic course, although the retro-aortic course may be associated with risk. Although the classic intra-arterial anomaly associated with increased clinical risk is the intra-arterial LMCA, intra-arterial LAD and RCA anomalies also are associated with increased risk.

An “intramural” course ( Fig. 9-2 ), completely within the wall of the aorta, appears to be a serious anomaly, associated with sudden death during athletic exertion. An anomalous intramural course often is associated with an angulated initial course. Anatomically, the initial segment of the coronary artery is entirely within the wall of the aorta, and there is one adventitia. Identification of an intramural course requires high-resolution imaging or surgical inspection.

Initially, the intra-arterial course of an anomaly itself was thought to be responsible for the clinical risk, with hypotheses such as compression of the anomalous course by the pulmonary artery trunk and aorta during dilation associated with exercise resulting in myocardial ischemia and clinical risk. It is increasingly being recognized, however, that it is the abnormal ostium or initial course of the coronary artery associated with the intra-arterial course that confers the risk. Abrupt (“tangential”) angulation of the initial course (take-off) may be associated with “kinking” of the artery and a slit-like ostium. It also has been hypothesized that spasm of the anomalous intra-arterial coronary artery contributes to myocardial ischemia and clinical risk.

At the same time, the surgical approach to intra-arterial coronary artery anomalies has evolved beyond aortocoronary bypass grafting to an increased focus on “un-roofing” or “marsupializing” the narrowed ostium/initial course.

Associations of Coronary Anomalies

Most coronary anomalies occur in isolation, i.e., without associated congenital cardiac or vascular anomalies. However, some forms of congenital heart disease are commonly associated with coronary artery anomalies.

Anomalies of Coronary Ostia and Course

See Box 9-1 and Figures 9-3 through 9-7 .