Hemodynamic effects of nifedipine in patients with asymptomatic aortic regurgitation: evaluation by Doppler echocardiography.
Nineteen asymptomatic patients affected by isolated chronic aortic regurgitation received 20 mg of nifedipine sublingually: the acute hemodynamic effects of nifedipine were evaluated by combined cross-sectional and Doppler echocardiography. To assess variations in the regurgitant flow volume, the flow volume across the mitral and aortic valves was calculated as the product of velocity-time integral multiplied by the orifice valve area. Flow volume across these valves represented the total stroke volume, and forward stroke volume, respectively: the regurgitant volume was obtained by calculating the difference between total and forward stroke volume. Nifedipine induced a redistribution of the two components of the total left ventricular stroke volume: regurgitant stroke volume decreased from 57 +/- 22 ml/beat to 46 +/- 21 ml/beat (P < 0.002), while forward stroke volume increased from 83 +/- 12 to 93 +/- 15 ml/beat (P < 0.0005), as a consequence of the reduction in systemic vascular resistance from 1513 +/- 378 to 1092 +/- 307 dynes.sec.cm-5 (P < 0.0001). The reduction of regurgitant volume was due to either a 24.8% decrease of the aortic-left ventricular mean pressure gradient during diastole (P < 0.008) or a 6% decrease of the diastolic time interval (P < 0.04). The effect of these acute changes on left ventricular loading was to induce a reduction in oxygen consumption which was expressed by a decrease in the double product (from 10176 +/- 1767 to 9444 +/- 1559 mmHg.beats/min; P < 0.002), in spite of a significant increase in heart rate. This study, therefore, shows the beneficial acute hemodynamic effect induced by nifedipine in asymptomatic patients affected by chronic aortic regurgitation and shows that Doppler-echocardiography is a useful instrument for the evaluation of hemodynamic changes immediately after the administration of drugs.
Gentile
F
F
Department of Cardiology, Bassini Hospital, Milan, Italy.
Ornaghi
M
M
Esposti
D
D
Triulzi
M O
MO
D000286:Administration, Sublingual; D000293:Adolescent; D000328:Adult; D000368:Aged; D001022:Aortic Valve Insufficiency / Q000000981:diagnostic imaging / Q000188:drug therapy*; D001783:Blood Flow Velocity / Q000187:drug effects / Q000502:physiology; D004305:Dose-Response Relationship, Drug; D004452:Echocardiography; D015150:Echocardiography, Doppler / Q000187:drug effects*; D005260:Female; D006439:Hemodynamics / Q000187:drug effects* / Q000502:physiology; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008297:Male; D008875:Middle Aged; D009543:Nifedipine / Q000008:administration & dosage* / Q000009:adverse effects
D009543:Nifedipine