Comparative systemic and renal effects of dopamine and angiotensin-converting enzyme inhibition with enalaprilat in patients with heart failure.

Renal and systemic hemodynamics were measured during titration of dopamine and serially after intravenous administration of enalaprilat in nine patients with chronic severe congestive heart failure. During titration of dopamine, renal blood flow increased by 99%, from 304 +/- 120 to 604 +/- 234 ml/min (p less than .01) at a dose of dopamine of 2.1 micrograms/kg/min, which produced only a 21% increase in cardiac index, from 1.96 +/- 0.36 to 2.38 +/- 0.35 liters/min/m2 (p less than .05). Cardiac index was increased maximally at a dose of 4.0 micrograms/kg/min dopamine; however, renal blood flow was not further augmented. In contrast, after intravenous administration of enalaprilat, peak improvement of renal blood flow and cardiac index occurred concomitantly. Renal blood flow increased by 35%, from 316 +/- 97 to 427 +/- 107 ml/min (p less than .05), and cardiac index increased by 18%, from 1.99 +/- 0.40 to 2.35 +/- 0.40 liters/min/m2 (p less than .05). At similar increases in cardiac index, dopamine produced a greater increase in renal blood flow than enalaprilat: 604 +/- 234 vs 427 +/- 107 ml/min (p less than .05). Mean systemic arterial pressure, however, was greater with dopamine than with enalaprilat (78.1 +/- 16.7 vs 70.2 +/- 17.2 mm Hg; p less than .05) at peak effect. Thus, although both drugs appear to be potent renal vasodilators in patients with severe congestive heart failure, dopamine may be more effective in augmenting renal blood flow.