Lack of correlation between the acute haemodynamic response to intravenous captopril and plasma concentrations of angiotensin II in patients with chronic cardiac failure

Abstract

We have given a series of incremental intravenous injections of captopril to ten patients with chronic cardiac failure. Small doses of captopril produced significant changes in pulmonary artery end-diastolic pressure and right atrial pressure, up to a total cumulative dose of captopril of 2.5 mg, after which further injections had no significant effect. There were large changes in systemic vascular resistance and blood pressure up to a cumulative dose of captopril of 5.0 mg, after which the injection of larger doses caused no further significant changes. Small doses of intravenous captopril produced large increases in plasma renin activity and plasma angiotensin I concentrations up to a total cumulative dose of captopril of 1.25 mg, after which there were no significant further changes in either plasma renin activity or plasma angiotensin I concentration. However the plasma concentration of angiotensin II fell more slowly, no further change being recorded after a total cumulative dose of captopril of 10 mg. These results suggest that plasma renin activity is not the only determinant of plasma angiotensin II concentrations.

Hemodynamic and hormonal effects of quinaprilat in patients with congestive heart failure*

“…AI1 of the hemodynamic changes observed in this study are consistent with observations made by others after open-label intravenous administratio,t of ACE inhibitors to patients with congestive heart failure. [15][16][17][18][19][20][21][22][23][24] Effects on enzyme (renin and ACE) activities and hormonal (angiotensin and aldosterone) concentrations after quinaprilat administration are generally consistent with responses observed in previous studies that examined the acute effects of intravenous ACE inhibitors in patients with congestive heart failure 15~17,21-22,23 although none of the other studies examined as extensively the hormonal profiles evaluated here. In this study, predose PRA and plasma concentrations of angiotensin II, aldosterone, norepinephrine, and ANP were in the upper range of or elevated above normal, whereas plasma ACE activity and plasma concentrations of epinephrine and dopamine were within normal ranges.…”