Effects of the single and repeated administration of benazepril on systemic and forearm circulation and cardiac function in hypertensive patients

The hemodynamic and cardiac effects of the new angiotensin-converting enzyme inhibitor, benazepril, were studied in 28 hypertensives in a double blind, placebo-controlled, between-patient study. Hemodynamic studies were performed noninvasively by means of M-mode echo (central hemodynamics and left ventricular systolic function), 2-D echo-Doppler (left ventricular diastolic function), and pulsed Doppler flowmetry (forearm circulation). Examinations were done at the end of a placebo run-in period and 3 hours after benazepril administration, both on the first day and after 6 weeks of treatment (10 or 20 mg once daily, according to patient response). In comparison with placebo, benazepril reduced systolic (p = 0.04) and diastolic (p = 0.003) blood pressure, because of a significant reduction in systemic vascular resistance (p = 0.03), while cardiac output was unchanged. Forearm vascular resistance was reduced and brachial artery compliance increased, although not to a statistically significant level (both p = 0.07). Both systolic and diastolic left ventricular function were positively influenced by the afterload reduction: End-systolic stress was reduced by 12% (p = 0.07), as was the late diastolic peak flow velocity (p = 0.02). All hemodynamic changes were evident after acute benazepril administration, and no differences was observed between acute and repeated treatment. We conclude that, similar to other ACE-inhibitors, benazepril reduces blood pressure through a reduction in vascular resistance, while cardiac output and heart rate are unaffected. These hemodynamic effects occur as early as after the first administration and exert a favorable influence on left ventricular dynamics.