Hemodynamic effects of nitroglycerin, propranolol, and their combination in coronary heart disease.

SUMMARY The hemodynamic effects of 10 mg of propranolol given intravenously (iv) were studied in 10 patients (group I) with coronary heart disease (CHD). These results were compared with the hemodynamic effects in a similar group of the nine (CHD) patients (group II) who were studied after administration of 0.6 mg of nitroglycerin and then after receiving 10 mg of propranolol iv with a second 0.6-mg dose of nitroglycerin. Measurements were obtained at rest and during exercise: before treatment, after nitro-glycerin alone, after propranolol alone, and after nitroglycerin-propranolol in combination. Pretreatment exercise showed a 125% increase in mean pulmonary artery pressure (PAP) to 43 mm Hg and a 163% increase in left ventricular end-diastolic pressure (LVEDP) to 29 mm Hg. Nitroglycerin decreased PAP (-45%) and LVEDP (-66%); as did nitroglycerin-propranolol: PAP (-33%) and LVEDP (-38%). Nitroglycerin reduced tension-time index (TTI)-21%, and increased cardiac index (CI) +17%, heart rate (HR) +10%, left ventricular work index (LVWI) +11%, and left ventricular dp/dt (LV dp/dt) +22%. By contrast, nitroglycerin-propranolol reduced LVWI-14%, LV dp/dt-30%, TTI-15%, and HR-13% but did not significantly alter CI from pretreat-ment. Propranolol increased PAP to 40 mm Hg, did not change LVEDP at 29 mm Hg and decreased stroke index (SI) 16%. Nitroglycerin-propranolol diminished PA and LVED pressure and increased SI 14%. Effects of propranolol alone and of nitroglycerin-propranolol on HR, TTI, and LV dp/dt were not significantly different. Nitroglycerin-propranolol appears to have important advantages over nitroglycerin or propranolol alone. A reduction in HR, TTI, and LV dp/dt, determinants of myo-cardial oxygen consumption, concurrent with improved left ventricular function, demonstrates a beneficial synergistic hemodynamic action for nitroglycerin combined with propranolol. S INCE 1859 nitrates have demonstrated clinical value in the treatment of angina pectoris. Nonetheless, the mechanisms of action of nitroglycerin and chemically related compounds remain a subject of continued Exercise hemodynamics controversy. Evidence obtained predominantly by indirect means suggests that the drug's beneficial effect results from reduced cardiac work and coronary vasodilation or both.1A