Blood Flow Dynamics of Left Coronary Artery in Hypertrophied Human Heart

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To clarify the characteristics of the left coronary blood flow velocity wave forms in left ventricular hypertrophy, we analyzed phasic flow velocity wave forms of left anterior descending coronary artery (LAD) in the patients with aortic regurgitation and stenosis before and after aortic valve replacement using an 80-channel 20 MHz pulsed Doppler velocimeter, and the influence of increase in heart rate on the velocity wave forms was studied by atrial pacing during cardiac operations.In aortic regurgitation, the LAD flow was characterized by an increase in the systolic flow component, a small and rapidly decreased diastolic flow. An increase in heart rate by pacing brought about a decrease in systolic flow and an increase in diastolic flow component. After aortic valve replacement, systolic flow decreased by 36.3 + 21.7%, whereas diastolic flow markedly increased by 81.4 + 51.8%. These findings suggest that the increase in heart rate in aortic regurgitation and aortic valve replacement … More induce beneficial effects on the myocardial inflow.The LAD flow velocity wave form in aortic stenosis was characterized by a reverse flow in systole and a slowly increasing diastolic inflow. The time from onset of diastole to the diastolic peak velocity (T-DPV) lengthened in all patients and did not change after an increase in heart rate by pacing. The apparent changes in diastolic flow pattern were observed at the pacing rate of 120, that was, the peak region of diastolic flow velocity overlapped with QRS of subsequent systole, therefore, increasing diastolic inflow rapidly decreased. These findings suggest that the increase in heart rate brings about markedly decrease in coronary blood flow in aortic stenosis. After aortic valve replacement, the increasing rate of the diastolic inflow was augmented and T-DPV was shortened from 176.8 + 28.8 to 90.5 + 18.8 cm/s. In addition, the diastolic peak velocity increased from 90.5 + 28.0 to 122.5 + 17.2 cm/s. These changes suggest the beneficial effects of removal of aortic stenosis on human coronary artery inflow. Less