Basic and Clinical Analysis of Macroscopic and Microscopic Characteristics of Coronary Circulation in Cardiac Hypertrophy

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It is well known that the heart can adapt itself to pressure overload or volume overload by inducing cardiac hypertrophy and thus reducing myocardial stress. Whereas, it is indicated that coronary reserve is decreased in hypertrophied heart. However, only little finding is reported on why coronary circulation is deteriorated in cardiac hypertrophy.In this study we measured coronary artery flow in human being with cardiac hypertrophy by 20 MHz ultrasound Doppler velocimeter, and epicardial and intramyocadial artery flow in dogs by laser Doppler velocimeter.We found that myocardiac contraction impedes coronary inflow and it may affect directly to intramyocardial vessels and the effect of intramyocadial pressure is relatively small. In addition we found that in human cardiac hypertrophy there exists reverse arterial flow in systole and that early diastolic flow is reduced. These findings suggest that myocadial contraction is a major factor determining phasic arterial flow and cardiac hypertrophy has complex effects on coronary circulation.