Preoperative evaluation of the structural lesion of the mitral valve by M-mode scan echocardiography

M-mode scan echocardiographic studies of the mitral valve were performed in order to investigate structural architecture of the diseased mitral valve. Structural lesion of the mitral valve was assessed by the echo-pattern change, an increase in number or thickness of the diastolic mitral echo complex. The echo-pattern was classified into 4 grades according to number or thickness of the mitral echoes. The echo-pattern grade correlated with the degree of the structural lesion of 21 surgically excised mitral valves. Clinically, the echo-pattern grade was compared with subsequent operative procedure in 56 cases with pure or predominant mitral stenosis (42 open commissurotomy, 14 valve replacement). Grade I or grade II echo-pattern was a good indicator for mitral commissurotomy. Grade IV pattern was a reliable criterion for valve replacement. Mitral valve replacement should be also considered in cases with grade III pattern, 38% of whom underwent valve replacement. C-E amplitude of the mitral valve was not a useful parameter in assessing the surgical procedure. Thus, the echo-pattern obtained by M-mode scan technique appeared to be of valve in planning the surgical approach for patients with pure or predominant mitral stenosis.