Regional diastolic coronary blood flow during diastolic ventricular hypertension.

The effect of diastolic ventricular hypertension on regional diastolic coronary flow was measured with radioactive microspheres in the canine heart paced at a constant rate and perfused only during diastole with a constant coronary perfusion pressure. Diastolic ventricular hypertension produced an homogenous increase of diastolic flow across the left ventricular wall when the metabolic coronary autoregulation was intact, but produced a decrease in subendocardial diastolic flow when the autoregulation was abolished. These results suggest that diastolic ventricular hypertension produces a higher subendocardial than subepicardial mechanical resistance to diastolic coronary flow.