 Doppler echocardiography will be performed prior to valve replacement, and repeated 3, 6, and 12 months after surgery. Examinations will be performed on a GE medical Vivid 5 ultrasound machine. Images will be obtained from the parasternal and apical windows. M-mode recordings will be done in the parasternal long-axis view. Pulsed Doppler measurements of mitral inflow will be obtained with the transducer in the apical four-chamber view, with a 1-2 mm Doppler sample volume placed between the tips of mitral leaflets during diastole. Tissue Doppler imaging of the mitral annulus will be obtained from the apical 4-chamber view with a 1.5-mm sample volume placed at the medial mitral annulus. All Doppler echocardiographic examinations are done with horizontal sweep set to 100 mms. At least 3-5 cardiac cycles will be measured. Finally color coded real time tissue Doppler images will be acquired in the apical windows. 