EFFECTS OF DOBUTAMINE INFUSION ON MITRAL REGURGITATION

Both intensity of mitral regurgitant murmur and color-coded Doppler re gurgitant signal area have been reported to correlate with the degree of regurgitation. To evaluate the relationship between the intensity o f regurgitant murmur and severity of mitral regurgitation, phonocardio graphy echocardiography, and Doppler ultrasound were performed in 18 p atients with mitral regurgitation before and during dobutamine infusio n. Mitral regurgitation teas due to mitral valve prolapse with rupture d chordae tendineae in 8 patients, rheumatic change in 5 patients, and dilated cardiomyopathy in 5 patients. With intravenous dobutamine inf usion, heart rate (77-103 beats/min), systolic blood pressure (119-144 mmHg), peak mitral regurgitant jet velocity (4.5-5.4 m / sec), intens ity of mitral regurgitant murmur (to 201% of that before infusion in e arly systole) increased, while left ventricular end-diastolic volume ( iota 24-102 mm), left ventricular end-systolic volume (57-42 mm), mitr al anular diameter (33-28mm), and color Doppler mitral regurgitant sig nal area (704-416 mm(2)) decreased (P < 0.05). Total (forward + backwa rd) left ventricular stroke volume (66-61 mL / beat) showed no change. Dobutamine decreased mitral regurgitant flow / beat, regardless of et iology of mitral regurgitation, which was probably due to the decrease of left ventricular size and mitral annular diameter. Although total (forward + backward) left ventricular stroke volume teas unchanged dob utamine effectively increased forward left ventricular stroke volume b y decreasing backward regurgitation. Mitral regurgitant murmur became louder despite the decrease of mitral regurgitation, indicating the us elessness of auscultation in the grading of the severity of mitral reg urgitation. (ECHOCARDIOGRAPHY, Volume 15, January 1998).