Abstract
In the present experiments the coronary artery catheter and dogs with unopened chests were used. The influence of cardiac contraction upon the coronary flow was studied during the cardiac arrest, ventricular fibrillation and cardiac weakness. A sudden cardiac arrest tended to reduce the coronary flow, while the ventricular fibrillation augmented the coronary flow. If the cardiac beat was weak enough to produce no systemic blood pressure, no coronary flow occurred. When the myocardial contractility was strong enough to produce systemic blood pressure, the coronary flow appeared. The stronger the cardiac beat, the larger the coronary flow. The increase in coronary flow associated with myocardial activity indicated that the volume of blood passing through the vascular bed of myocardium was augmented by increased force of the heart-beat. With regard to the phasic change in the coronary flow, the ventricular contraction impeded coronary flow and the diastole acted in aid of the flow.
