Abstract

Coronary arteries distribute flow over the epicardium and branch into transmural arteries, which over about 10 orders of branching nodes connect to the capillary bed for exchange of nutrients between blood and tissue. Understanding of the 3-dimensional structure of the intramural vascular system is needed to understand local mis-balance between supply and demand that especially may occur at the subendocardium. This mis-balance is the explanation for the observation that infarctions most often start at the subendocardium. The intramural vascular structure of larger animals and humans can now be studied by a novel imaging cryomicrotome (slicing at 40 microns, in plane pixels of cutting plane images: 4000*4000) by studying the distribution of fluorescently labeled elastomer by which the arterial system is filled. Flow distributions are then measured from fluorescently labeled microsphere distributions (5 colors) injected at different physiological conditions with the heart still in situ. Since microsphere distribution and arterial structure are measured in the same heart, for the first time intramural vascular structure and flow distribution can be studied concomitantly.