Acute and long-term response to an oral converting-enzyme inhibitor, captopril, in congestive heart failure.

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Abstract
Captopril (SQ 14,225), an oral angiotensin converting-enzyme inhibitor, was administered to 11 patients with severe congestive heart failure (CHF). Peak effect was observed at 1.5 h after administration. At peak effect right atrial pressure fell from 3.4 to 0.0 mm Hg, pulmonary capillary wedge pressure (PCW) fell from 22.7 to 12.3 mm Hg, mean arterial pressure (MAP) feel from 79.5 to 62.1 mm Hg, systemic vascular resistance (SVR) fell from 1989 to 1370 dyn-s-cm-5, pulmonary vascular resistance fell from 843 to 523 dyn-s-cm-5 and cardiac index (CI) rose from 1.96 to 2.43 l/min per m2. These were all statistically significant. Control plasma renin activity (PRA) was elevated (25.9 ng/ml per h) and correlated with resting PCW (r = 0.65). The acute hemodynamic response was related to PRA: a fall in MAP (r = 0.74), a fall in PCW (r = 0.80), a fall in SVR (r = 0.45) and a rise in CI (r = 0.45). Eight patients were placed on chronic captopril therapy. After 2 or more months their exercise time significantly increased from 6.8 to 11.7 min. Their cardiothoracic ratios showed a significant decrease, from 0.55 to 0.52, and most patients reported symptomatic improvement. Chronic response was not predicted by acute hemodynamic response. Captopril is a vasodilator with arterial and venous effects that are at least partially caused by inhibition of the renin-angiotensin system. It may be useful for the treatment of CHF.