Hemodynamics and coronary flow following diltiazem administration in anesthetized dogs and in humans

In this study, the systemic and coronary hemodynamic changes associated with the administration of diltiazem, a recent calcium antagonist, were evaluated in three different situations as follows: following a 200 microgram/kg intravenous bolus of the drug in 12 open-chest anesthetized dogs; following two successive intravenous infusions of diltiazem (15 microgram/kg/min and 30 microgram/kg/min), each for a period of ten minutes, in eight patients with angina pectoris investigated by coronary arteriography; and following a single oral dose of 120 mg of diltiazem in 17 patients undergoing hemodynamic monitoring in the coronary care unit after a recent myocardial infarction. Diltiazem was found to be a coronary vasodilator acting on the large coronary arteries and on collaterals. Its effects on myocardial oxygen requirements were variable; as a rule, the predominant effect was a drop in systemic vascular resistance or in heart rate. When systemic vascular resistance changed little, heart rate tended to decrease significantly; however, when systemic vascular resistance decreased notably, heart rate remained unchanged because of a relfex attempt to increase systemic blood pressure. Cardiac performance and left ventricular end-diastolic pressure were not affected and this lack of change in cardiac inotropism may confer and advantage to diltiazem over other calcium antagonistic drugs in patients with coronary heart disease.