Left ventricular pump function in effort angina. Influence of nitroglycerin, propranolol, verapamil, and coronary bypass surgery.

Patients with severe effort angina were studied hemodynamically and left ventricular function curves were obtained during successively increasing myocardial ischemia provoked by exercise. The mean left ventricular function curve of 57 patients showed a slow increase in stroke work index with increasing left ventricular end-diastolic pressure at the beginning of exercise and stroke work index reached a maximum value of 0.79 (+/- 0.21) J/beat/m2 BSA at a left ventricular end diastolic pressure 30 (+/- 7) mm Hg. Despite a continuous increase in left ventricular end-diastolic pressure to 37 (+/- 6) mm Hg at the breaking point, stroke work index fell to its lowest value (0.64 +/- 0.21) J/beat/m2 BSA. A repeated exercise 20 min after the first in 10 patients did not influence the exercise tolerance or the left ventricular function curve. Although all the drugs nitroglycerin, propranolol and verapamil significantly increased the exercise tolerance none of the drugs enabled the patients to reach a significantly higher stroke work index. Only after nitroglycerin was there a significant increase (p greater than 0.05) of left ventricular power. After coronary bypass surgery with successful revascularization, however, there was a marked increase of both stroke work index and left ventricular power during exercise. Thus the increased exercise tolerance after surgery was accompanied by an increased left ventricular work and power but after medication no such effect on stroke work index and left ventricular power was seen. It is therefore suggested that the increased exercise tolerance after the anti-anginal drugs studied is a result of their different mechanisms of unloading the left ventricle.