BME approach to understand blood supply to the heart

Since the major parts of coronary circulation run in the myocardium which continues contraction and relaxation, the flow-velocity waveforms of the arterial inflow and the venous outflow of myocardium are quite unique; the arterial flow is exclusively diastolic while the venous flow is systolic. In this paper, some results of visualization of transmural microvessels with their flow directions by our needle-probe CCD microscope were introduced with the interpretation of the arteriolar and venular hemodynamics through a cardiac cycle. Especially, the slosh phenomenon (to and fro movement of blood) of the arterioles in deeper myocardium was emphasized as a possible cause of higher incidence of ischemia. Then, the importance of spatial heterogeneity of blood supply to myocardium was described with reference to minimal vascular control unit (ca 500 /spl mu/m), which was investigated by a molecular tracer method. The higher global heterogeneity with less local randomness is the characteristic of the flow heterogeneity in deeper myocardium. This may also relate to higher vulnerability of the deeper portion to ischemia.