The effects of pretreatment with nitroglycerin on ischemic left ventricular dysfunction during coronary angioplasty.

To evaluate the degree to which nitroglycerin reduces myocardial ischemia and dysfunction induced by transient coronary occlusion, 19 patients were studied during coronary angioplasty of the left anterior descending coronary artery. After a control occlusion of 60 seconds, 0.2 mg nitroglycerin was administered intravenously and the occlusion was repeated for 60 seconds. Before and during the occlusion period, pulmonary capillary wedge pressure was measured, the intracoronary ECG was recorded, and ventricular volumes, ejection fraction, and regional systolic shortening were obtained by digital subtraction angiography. Nitroglycerin caused a significant fall in pulmonary capillary wedge pressure before (10 vs. 7 mmHg) and at 60 seconds occlusion (18 vs. 14 mmHg), but did not significantly delay the rise in wedge pressure (37 vs. 44 seconds). End-systolic left ventricular volume at 60 seconds of occlusion was reduced by nitroglycerin (77 vs. 68 ml), whereas regional shortening of the ischemic segments remained unchanged (22 vs. 23%). Nitroglycerin did not delay the onset of ischemic ST-segment elevation (14 vs. 14 seconds) and had no effect on the changes of ST elevation in the intracoronary ECG (1.9 vs. 1.9 mV). These findings suggest that intravenous nitroglycerin reduces filling pressure and slightly improves left ventricular global function during acute coronary occlusion. Nitroglycerin, however, has little effect on ischemia-induced regional dysfunction and on ST-segment elevation in the intracoronary ECG.