Left heart hemodynamics during angina pectoris induced by atrial pacing.

In order to determine the associated hemodynamic events, angina pectoris was induced by an atrial pacing technic. In all patients developing angina pectoris, ischemic changes were noted electrocardiographically. The hemodynamic findings were variable: in some patients no changes were noted; in others, significant increases in cardiac output, left ventricular end-diastolic pressures (LVEDP), and femoral arterial and pulmonary arterial pressures occurred. These changes suggest that, initially, ischemia produces a decrease in myocardial compliance and this may also be associated with enhanced sympathetic nervous system activity. Myocardial failure may subsequently ensue, however. The administration of nitroglycerin, during angina at a fixed rapid heart rate, resulted in a reduction in LVEDP and cardiac work. Chest pain was always relieved following these hemodynamic changes, indicating a dependence upon these changes for the effective-