Hemodynamic effects of isosorbide-5-mononitrate in acute and chronic treatment of coronary heart disease.

Hemodynamic effects of isosorbide-5-mononitrate (IS-5-MN) were studied in 20 patients with coronary heart disease. Three hours after the first administration of 50 mg IS-5-MN we found a significant decrease in mean pulmonary artery pressure, while heart rate and arterial blood pressure remained unchanged. Concomitant with the hemodynamic effects we found a decrease in angina pectoris and normalization of exercise-induced ST depression. After 50 mg IS-5-MN three times daily for 1 week the repeated acute administration of a single dose of 50 mg produced a fall in mean pulmonary artery pressure at rest (-25%) and during exercise (-20%), while the antianginal effect was unchanged. Six hours after a repeated single dose we found no change in hemodynamic parameters as compared with the control levels before treatment. The decreased effect on the pulmonary artery pressure under chronic treatment is discussed as a development of tolerance with decrease of venous pooling. The unchanged antianginal effect is difficult to understand, and may be interpreted as due to an influence on the coronary vessels and collateral blood flow.