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Acute and long-term effects of captopril on left and right ventricular volumes and function in chronic heart failure
Abstract:
To more fully delineate the effects of captopril (CPT) on cardiac size and function in patients with chronic congestive heart failure (CHF), we performed blood pool scintigraphy in conjunction with hemodynamic measurements during the initiation of vasodilator therapy and repeat scintigraphy after 2 and 12 weeks. Measurements of both right and left ventricular volumes and ejection fraction were made before and 90 minutes after the first 25 mg dose of CPT in 14 patients. Overall, heart rate fell modestly, from 82 +/- 10 to 77 +/- 11 bpm (p less than 0.01), while mean arterial pressure dropped considerably, from 86 +/- 10 to 73 +/- 13 mm Hg (p less than 0.01). Left ventricular end-diastolic and end-systolic volumes fell from 388 +/- 81 to 350 +/- 77 and 319 +/- 75 to 271 +/- 75 ml (both p less than 0.01). Right ventricular end-diastolic and end-systolic volumes also decreased. The left ventricular ejection fraction rose modestly but significantly, from 19 +/- 6% to 22 +2- 5% (p less than 0.01), as did right ventricular ejection fraction (25 +/- 9% to 29 +/- 11%, p less than 0.01). Simultaneous hemodynamic measurements demonstrated corresponding decreases in left and right ventricular filling pressures (24 +/- 10 to 17 +/- 9 to 10 +/- 5 to 6 +/- 5 mm Hg, respectively, both p less than 0.001). The slight increase in cardiac and stroke indices at 90 minutes, from 2.0 +/- 0.5 to 2.1 +/- 0.4 and 25 +/- 8 to 27 +/- 7 ml/m2, respectively, were not significant, although both indices rose significantly at the time of each individual's peak effect. Six patients were discharged on CPT and underwent follow-up nuclear studies: the acute decrease in ventricular volumes were sustained, as was the slight improvement in ejection fractions. These findings indicated that the major acute effect of CPT in CHF is a reduction in the preload of both ventricles. This reduction in diastolic volumes and pressures persists during chronic therapy.