[ECG dynamics at rest and during exertion after mitral commissurotomy].

Four degrees of left atrial electrical activity were identified by ECG made before and after closed mitral commissurotomy in 70 patients with mitral stenosis and sinus rhythm. The critical electrical activity of the left atrium and hypertrophy of the right ventricle along with the typical auscultation pattern of mitral stenosis were found to cardiographically correspond to critical stenosis of the left atrioventricular ostium in most cases. The area of the mitral orifice, which was attributable to that of the body, was 0.