Systemic and Coronary Energetics in the Resting Unanesthetized Dog

This report is an initial attempt to study the coronary circulation in the chronic unanesthetized dog. A standardized preparation has been developed in which phasic aortic pressure and flow, phasic left coronary inflow, and myocardial metabolism have been studied for many weeks in the unanesthetized dog under resting conditions. The flow patterns in the main left coronary artery and in its major branches are very similar. In the resting dog, the left coronary inflow during systole is 7 to 45% of that during diastole. We believe that much of this flow into the epicardial arteries penetrates into the myocardium. Stroke coronary flow can change considerably without significant alterations of blood pressure and heart rate. Despite this, the coronary flow values (37 to 58 cc) and oxygen usage values (4.4 cc to 8.6 cc) per 100 grams left ventricle per minute are low. Since, however, these measurements can vary considerably not only in different dogs but also in the same dog on the same day, and from day to day, it is suggested that these animals were in a semiresting state and probably not in a basal state.