The goal of this study was to test the hypothesis whether a small balloon placed within the mitral orifice and pulsed in a synchronous manner could reduce the degree of acute mitral regurgitation. Previous experimental studies had shown that a similar balloon within the aortic orifice relieved satisfactorily aortic regurgitation. Acute mitral regurgitation was created in 14 dogs, and a catheter with a small polyurethane balloon on its distal end was introduced to the mitral ring through the left ventricular apex. The balloon was connected to a Datascope pump for intermittent, synchronous pulsation. Left atrial, left ventricular and aortic pressures were monitored. In three animals transesophageal echocardiography was used in addition to monitor the regurgitant transmitral flow with color Doppler image. Intermittent inflation of the balloon during systole decreased the maximum left atrial pressure from 31.83 mmHg +/- 3.48 mmHg to 23.16 +/- 3.3 mmHg (p < 0.001) and the mean left atrial pressure from 21.66 +/- 2.8 mmHg to 17.25 +/- 2.76 mmHg (p < 0.001). The systolic gradient across the mitral valve increased from 59 +/- 14.53 mmHg to 77.11 +/- 12.44 mmHg (p < 0.01). Transesophageal echocardiography showed an almost 50% decrease of the transmitral regurgitant flow. It is concluded that intermittent, systolic, synchronous balloon pulsation within the mitral orifice reduces the degree of experimental, acute mitral regurgitation.