There are congenital variations from the normal coronary artery anatomy that have significant clinical importance. There are many permutations of the origin site and course of the three primary coronary arteries (left anterior descending, left circumflex, and right coronary artery). The most clinical significant variations include:
- Single coronary artery originating either from the left or right sinus of Valsalva.
- Left main coronary artery or LAD originating from the right sinus of Valsalva.
- Anomalous left coronary artery originating from the pulmonary artery.
If the anomaly has the left main or left circumflex artery coursing between the aorta and pulmonary artery, then external compression of the vessel can occur resulting in myocardial ischemia, syncope, and sudden cardiac death. The obstruction may also result from the intramural course and acute angle of takeoff. Symptoms are worsened by exertion because there is dilation of the aortic root with increased cardiac output.
Origination of coronary vessels from the pulmonary artery is especially troublesome. The pulmonary artery has a low perfusion pressure and carries deoxygenated blood which results in hypoperfusion of the myocardium.
A much rarer condition can occur with anomalous origin of the right coronary coronary artery from the left main, a single left coronary artery, or directly from the aorta in the left sinus of Valsalva. The RCA the course to the right between the aorta and pulmonary artery which subjects it to the same extra-luminal compression and resulting myocardial ishcemia and increased risk of sudden cardiac death.
In contrast, origination of the left circumflex from the right sinus of Valsalva is well tolerated because it tends to course behind the aorta rather than between the aorta and pulmonary artery.