Coronary arterial capacitance and subendocardial vascular patency throughout the cardiac cycle
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Coronary blood flow undergoes phasic and transmural changes throughout the cardiac cycle. The mechanisms of these changes have not been completely elucidated. This thesis studied the role of coronary arterial capacitance in temporal and transmural variation of coronary flow. It was hypothesized that coronary arterial capacitance may change the phasic coronary inflow pattern temporally at microcirculatory level and redistributes myocardial blood flow transmurally. The pressure within this capacitive function may act as the distending pressure to maintain vascular patency throughout the cardiac cycle. These hypotheses were tested with two different experimental approaches.;In the first series of experiments, the role of coronary arterial capacitance in temporal variation and transmural distribution of the regional blood flow was studied in 15 dogs. In another series of experiments, the exchange vessel patency during normal and subendocardial hypoperfusion was studied by comparing the transmural pattern of exchange vessel surface area with the simultaneous flow pattern in 21 dogs.;The results of these two studies suggest that although the apparent coronary inflow ceases during systole, the flow at the exchange level persists throughout the cardiac cycle with the coronary arterial capacitance as the potential driving pressure. (Abstract shortened with permission of author.).