This paper presents a semi-automatic method for the segmentation and the tracking of the mitral valve leaflet in transesophageal echocardiography. We use two connected active contours in order to track efficiently the mitral leaflet. Segmentation of very fast and non rigid motions involved are realized in two steps. In the first step we use transformation fitting to provide a rough segmentation that will be refined in a second step using snakes with Dynamic Programming minimization. The method successfully tracks the inner cardiac muscle and the mitral valve leaflet axis. Keywords : Medical Image Analysis, Tracking and Motion, Active Contour, Ultrasound Imaging.