The innateness of coronary artery: Vasa vasorum.

Because heart originates from primitive endocardial tube (ventral aorta) embryologically, coronary arteries that supply this tube can be thought as "cardiac vasa vasorum" like arterial vasa vasorum that supply peripheral arteries. Coronary arteries have vasodilative reaction to noradrenaline, different from the most arteries that show vasoconstriction. This phenomenon is similar to vasa vasorum that are insensitive to noradrenaline and has its own vasoregulation. Coronary arteries can supply blood from epicardium, myocardium to endocardium under normal physiological conditions. But heart having a significant myocardial hypertrophy can be susceptible to subendocardial ischemia because the metabolic demands of hypertrophic myocardium cannot be met by a parallel increase of coronary myocardial capillaries. This peculiar characteristic of coronary arteries is similar to vasa vasorum that give rise to ischemic necrosis of media of the host vessel under chronic hypertension. Inherency of coronary arteries is the same endarteries as vasa vasorum. Coronary arteries have many smooth muscle fibers than elastic fibers in media, which protect them to collapse during systole to some extent. This feature also is similar to vasa vasorum. The above similarities support the hypothesis that coronary arteries are a kind of vasa vasorum.