Acute hemodynamic effects of terazosin in hypertensive and normotensive patients

Abstract

Terazosin, a selective α 1-adrenergic antagonist, was administered intravenously to 10 patients undergoing cardiac catheterization to determine its short-term hemodynamic effects. Hemodynamic measurements were performed before and 30 minutes after three doses of the drug: 1, 1, and 3 mg. One milligram of terazosin reduced the blood pressure (systolic/diastolic, mean) from a mean of 152.0 86.3 , 110.7 mm Hg by −24.3 −9.4 , −15.3 mm Hg ( p < 0.05). In the five patients who received 5 mg of the drug, blood pressure declined in a dose-dependent manner by −21.8 −3.8 , −11.6 mm Hg after 1 mg, and by −35.8 −14.8 , −22.8 mm Hg ( p < 0.05) after all 5 mg of the drug. The changes in blood pressure paralleled the terazosin-induced decrease in systemic resistance. Similar changes were recorded for pulmonary artery and capillary wedge pressures and pulmonary vascular resistance. The greatest hemodynamic response was noted with the first drug dose; succeeding doses had a progressively diminished incremental effect. Cardiac output, heart rate, and maximum left ventricular dp dt demonstrated little change, whereas left ventricular end-diastolic pressure decreased after all three doses, reaching significance after 2 mg (−3.4 ± 0.9 mm Hg, p < 0.05), and left ventricular ejection fraction tended to increase (+ 5.6% ± 2.4%, p < 0.05 after 1 mg) and showed a dose dependence analogous to that of systemic resistance. Although not generally reaching statistical significance, indexes of aortic stiffness and compliance displayed a favorable effect. These data are consistent with terazosin's specific α 1-antagonism. Left ventricular performance is improved by afterload reduction, since terazosin demonstrated no direct effect on cardiac contractility. The reduction of systemic vascular resistance, coupled with reduction in blood pressure, pulmonary capillary wedge pressure, pulmonary vascular resistance, and improved left ventricular performance without myocardial depression after intravenous terazosin, makes this agent a useful adjunct in antihypertensive therapy.