ASSESSMENT OF HEMODYNAMIC-EFFECTS OF ANGIOTENSIN-CONVERTING ENZYME-INHIBITOR THERAPY IN CHRONIC AORTIC REGURGITATION BY USING VELOCITY-ENCODED CINE MAGNETIC-RESONANCE-IMAGING

Long-term treatment with angiotensin-converting enzyme (ACE) inhibitor s has beneficial effects in patients with chronic aortic regurgitation by reducing left ventricular volumes and regurgitant fraction. Veloci ty-encoded cine magnetic resonance imaging can directly measure antegr ade (forward stroke volume) and retrograde blood flow (regurgitant vol ume)in the ascending aorta. Velocity-encoded cine magnetic resonance i maging was used in 9 patients with moderate to severe aortic regurgita tion (regurgitant fraction 49% +/- 17%) to measure regurgitant fractio n, regurgitant volume, and forward stroke volume at baseline and 3 mon ths after therapy with enalapril (mean dose 29 +/- 13 mg). Ten additio nal patients with aortic regurgitation without any drug therapy served as a control group. In the treatment group, systolic blood pressure s lightly decreased from 132 +/- 20 mm Hg to 121 +/- 14 mm Hg (p = not s ignificant), whereas diastolic blood pressure and heart rate (beats pe r minute) remained unchanged. Regurgitant fraction decreased In 6 pati ents (responders) from 49% +/- 19% to 39% +/- 20% (percentage change 2 4% +/- 14%, p = 0.002) and was unchanged In 3 patients (nonresponder, 49% +/- 19% vs 51% +/- 16%; p = not significant). In the responder gro up, forward stroke volume increased from 128 +/- 32 ml to 148 +/- 57 m l, whereas regurgitant volume remained unchanged (67 +/- 40 ml vs 65 /- 51 ml). At baseline, the responder group had a significant higher t otal vascular resistance than the nonresponder group (998 +/- 538 dyne . sec . cm(-5) vs 625 +/- 214 dyne . sec . cm(-5);p < 0.05). With ena lapril treatment, total vascular resistance In the responder group ten ded to decrease (891 +/- 576 dyne . sec . cm(-5)), but slightly increa sed in the nonresponder group (679 +/- 276 dyne . sec . cm(-5)). The c ontrol group showed no changes in regurgitant fraction, regurgitant vo lume, forward stroke volume, and total vascular resistance at follow-u p.