Echocardiographic studies following mitral valve replacement

Abstract

This chapter describes the application of echocardiography to studying alterations in the pattern of left ventricular filling due to mitral valve replacement, and so differs from previous investigations in which echoes have been recorded from the homograft1 or prosthesis² itself. The method depends on recording echoes simultaneously from the inter-ventricular septum and the endocardial surface of the posterior wall of the left ventricle. The distance between the two represents the transverse dimension of the left ventricle and is derived from an echocardiogram using a simple digitising technique that has been described elsewhere. This dimension is plotted, together with its rate of change, continuously throughout the cardiac cycle and a typical example from a normal subject can be seen in Figure 20.1. In normal subjects, the peak rate of increase of dimension of the left ventricle during the rapid phase of filling has a mean value of 10 cm S−¹;, but is only maintained for a short period at the start of diastole. In the presence of rheumatic mitral stenosis, the filling pattern is significantly modified and in 10 patients who required valvotomy, had a mean value of 4 cm S−¹;. In addition, the rapid early phase was lost, but lower levels were maintained throughout the period of ventricular filling.