Diastolic changes in left ventricular wall thickness studied by echocardiography

In order to study factors influencing posterior wall thickness during diastole, echocardiograms showing the septum, mitral valve and posterior wall endocardium and epicardium in 15 normal subjects and 49 patients with heart disease were digitized. Maximum wall thickness, minimum cavity dimension and the onset of mitral valve opening are normally synchronous, and an early period of rapid wall thinning, at a peak rate of 10.7 ± 1.7 cm/sec corresponds closely to rapid filling. In patients with ischaemic heart disease the peak rate and duration of rapid thinning were normal, but thinning preceded mitral valve opening (mean 50 msec). In 11 of 17 patients with hypertrophic cardiomyopathy the peak rate of thinning was reduced and in 2 it was increased. There as a close correlation between the peak thinning rate in this group and the peak rate of increase in dimension. In mitral stenosis peak thinning rate was frequently reduced but in some patients was normal, with the reduced rate of increase in cavity dimension maintained by reversal of septal movement. We conclude that rapid thinning is an intrinsic property of the ventricular wall which is normally associated with rapid filling, but which may be dissociated from filling by asynchronous relaxation or inflow obstruction, or may be modified by myocardial disease.