The Assessment of Mitral Stenosis by Phonocardiography

Clinical assessment of the severity of mitral stenosis sometimes presents difficulties. The symptoms may be obscured by superadded effort syndrome or by limitation of activity imposed by the patient's doctor. The physical signs may reveal the presence of pulmonary hypertension or heart failure, but in their absence there may be little indication as to the size of the mitral orifice. The intensity of the diastolic murmur is of little value since the stenosis may be severe when the murmur is slight or even absent. The degree of pulmonary hypertension measured at cardiac catheterization and the degree of right ventricular hypertrophy on the electrocardiogram are not necessarily indications of the severity of mitral stenosis. When all the evidence is considered the assessment is reasonably accurate, but there is obvious room for more direct evidence as to the degree of stenosis. The crucial information required is the pressure gradient across the mitral orifice or the rapidity of filling of the left ventricle. Such information is not necessarily an indication of the size of the mitral orifice for the ability of the left ventricle to fill in diastole must be determined in part by the involvement of the chordx tendinew, by the location and mobility of the mitral orifice, and by myocardial factors. The present study provides evidence that the pressure gradient across the mitral valve and the rapidity of filling of the left ventricle can be estimated by a phonocardiographic technique.