Diastolic movement of mitral valve in hypertrophic cardiomyopathy. An echocardiographic study.

Diastolic movement of the mitral valve and its relation to various aspects of left ventricular anatomy and function has been investigated in 15 patients with hypertrophic cardiomyopathy. Echocardiograms showing left ventricular cavity and mitral valve simultaneously were recorded and subsequently digitised in order to obtain continuous plots of left ventricular dimension, its rate of change, and peak diastolic closure rate of the anterior leaflet of the mitral valve. Septal and posterior wall thicknesses, together with left ventricular cavity and outflow tract dimension in mid-systole, were also measured directly on the echocardiograms. All the measurements were compared with those in 14 normal subjects. Patients with hypertrophic cardiomyopathy had smaller ventricles, with a conspicuous increase in septal thickness compared with those of normal subjects. Posterior wall thickness was only slightly increased, rapid filling period was normal, whereas both the peak rate of increase of left ventricular dimension and the peak mitral diastolic closure rate were low. However, no relation between these two indices was found. Instead, mitral valve closing velocity was strongly correlated with left ventricular outflow tract dimension. This relation was further validated by the infusion of isoprenaline, resulting in a simultaneous reduction of left ventricular outflow tract dimension and peak mitral closing velocity.