Effect of graded narrowing of left main coronary artery on left ventricular function

The relationship between left ventricular function and coronary blood flow was studied in 16 chloralose-anesthetized dogs with an intact coronary circulation and left ventricle. Left ventricular dimensions, hemodynamic function indices, and coronary blood flow were measured simultaneously as the origin of the left coronary artery was narrowed by a calibrated snare. With a left coronary blood flow reduction of 17% (average), left ventricular minor axis diameter increased and maximum aortic blood flow acceleration and maximum rate of rise of left ventricular pressure decreased. Other measured indices of ventricular function did not change significantly. Larger coronary flow decrements caused a decrease in aortic systolic and diastolic pressures, stroke volume and cardiac output and an increase in heart rate and left ventricular end-diastolic pressure. These results confirm a close relationship between left ventricular function and blood supply.