Transmural distribution of myocardial blood flow and of coronary reserve in canine left ventricular hypertrophy.

Left ventricular hypertrophy was induced by banding of the ascending aorta in pupies at the age of 6 weeks. At the age of one year left ventricular weight per body weight was increased by 87% compared to control litter mates. While myocardial perfusion and myocardial oxygen consumption per 100 g were identical in the hypertrophy and control group, there was a significantly diminshed ratio of subendocardial/subepicardial flow in the hypertrophy group during moderate exercise. With maximal coronary dilation subendocardial diastolic resistance (mm Hg/ml-min-1 per 100 g) was 0.16 +/- 0.03 in the control group and 0.26 +/- 0.03 in the hypertrophy group. This diminished coronary reserve indicates an insufficient growth of the vascular bed in these hypertrophied hearts.