Improvement of Coronary Blood Flow by Augmentation of Coronary Vascular Compliance

Coronary blood flow occurs predominantly during the diastolic period of the cardiac cycle. This study investigated the effects of increasing the diastolic coronary perfusion pressure by artificially increasing the epicardial coronary capacitance function, using a buffer chamber. The left anterior descending (LAD) coronary artery was cannulated in six dogs and perfused by tubing via the carotid artery. A significant stenosis was produced with a screw clamp, resulting in a distal coronary pressure of about 35 mm Hg. A buffer chamber was placed on the perfusion line distal to the stenosis to buffer the distal coronary perfusion pressure. Myocardial blood flow as measured by microspheres showed a 39.6% increase in blood flow during buffered perfusion as compared to nonbuffered perfusion: 0.415 +/- 0.279 versus 0.316 +/- 0.238 ml/min/g. The calculated diastolic pressure time index (DPTI) increased 54.1% during buffered perfusion. Flow increased significantly in the endocardial and mid-wall layers but not in the epicardium. It is concluded that coronary blood flow can be augmented by increasing the coronary capacitance function in this model.