Improved intraoperative evaluation of mitral valve operations utilizing two-dimensional contrast echocardiography

Abstract

Whenever possible, precise mitral valve repair is preferable to valve replacement. Present methods for intraoperative detection of mitral regurgitation, primarily hemodynamic measurements and direct palpation, may underestimate or not detect the presence and severity of regurgitation. We have investigated two-dimensional contrast echocardiography as a means of improving our intraoperative assessment of mitral valve function both before and after repair or replacement. After exposure of the heart, a baseline two-dimensional echocardiogram (in modified long- and short-axis planes) is performed using a hand-held 5 mHz mechanical transducer. Five milliliters of agitated 5% dextrose in water is injected into the left ventricle through a transseptal needle to generate detectable microbubbles. In the absence of mitral regurgitation, virtually all microbubbles exit through the aorta; in the presence of regurgitation, a mass of microbubbles reflux into the left atrium. After repair of the mitral valve and immediately after bypass, the contrast echocardiogram is repeated and hemodynamic measurements are obtained. Forty-three patients (37 with mitral valve disease and six additional patients without mitral disease) undergoing cardiac operations were evaluated. Experience with intraoperative two-dimensional contrast echocardiography has accurately demonstrated relatively small degrees of mitral regurgitation when conventional techniques failed to do so and has allowed more precise repair of the residual regurgitation. Two commissurotomy and two annuloplasty patients who were thought to have satisfactory repairs underwent immediate second procedures because of significant residual mitral regurgitation demonstrated solely by this echocardiographic microbubble technique. No complications associated with this technique have developed. We conclude that intraoperative two-dimensional contrast echocardiography is a sensitive and safe technique that allows intraoperative detection of even small degrees of mitral regurgitation and provides a basis for precise repair of mitral valve lesions.