Why are the intramyocardial portions of the coronary arteries spared from arteriosclerosis? Clinical implications.

Experienced cardiac surgeons are aware that the intramyocardial portions of the coronary arteries are rarely affected by arteriosclerosis. This is a striking and reliable finding in the operating room that is present even when the preceding and subsequent segments of the arteries are diseased. The present review describes the published evidence of embryological, anatomical and physiological differences between intramyocardial coronary arteries and their epicardial counterparts. Possible mechanisms of these differences are explored, and hypotheses are advanced as to how one may capitalize on these differences to provide better diagnosis and treatment of coronary artery disease. The absence of vasa vasorum in the intramyocardial coronary arteries appears to play a major role in their protection from arteriosclerosis. Fully understanding this peculiar phenomenon - the sparing of the intramyocardial coronary arteries - would be one giant step closer to unlocking the remaining mysteries of arteriosclerosis in general.