Effects of short-term intravenous administration of diltiazem on left ventricular function and coronary hemodynamics in patients with coronary artery disease

The hemodynamic effects of diltiazem were investigated in 15 patients with suspected coronary artery disease undergoing routine cardiac catheterization. Diltiazem was given in a high dose of 500 micrograms/kg over a period of 5 min and measurements made before and after drug administration during spontaneous heart rate and during matched atrial pacing. Spontaneous heart rate did not change (-5%; NS). Left ventricular (LV) systolic pressure decreased 24% (p less than 10(-6)) and LV end-diastolic pressure (LVEDP) did not change (-5%; NS). During coronary blood flow measurement, mean aortic pressure decreased 30% (p less than 10(-6)) as global (coronary sinus) and regional (great cardiac vein) coronary vascular resistance diminished with no change in coronary blood flow. Myocardial oxygen consumption decreased 19% (p less than 0.02). During matched pacing, although no change occurred in calculated systolic isovolumic indexes of contractility, end-systolic pressure-volume index decreased 15% (p less than 0.05). The time constant of isovolumic relaxation assessed by a biexponential model decreased. No net change occurred in either global or regional wall motion. In summary, high-dose diltiazem was administered safely to patients with coronary artery disease. It is concluded that, at this dose, diltiazem acted as a peripheral and coronary vasodilator. Hemodynamic changes consistent with a direct negative inotropic and chronotropic effect of the drug were observed. Myocardial oxygen consumption decreased with no change in coronary blood flow.