Mechanism of paradoxical early diastolic septal motion in patients with mitral stenosis: A cross-sectional echocardiographic study

Abstract

Paradoxical motion of the interventricular septum in early diastole has been observed in patients with mitral stenosis. To evaluate the cause of this septal motion abnormality M mode and cross-sectional echocardiograms were performed in 36 patients with mitral stenosis and 20 normal subjects. Cross-sectional studies in the normal subjects (Group I) and 9 of 11 patients with minimal septal motion abnormality (Group IIA) showed normal left ventricular diastolic shape and relaxation pattern. In 23 of 25 patients with more severe septal motion abnormality (Group IIB) there was a distinct change in initial diastolic left ventricular shape, characterized by motion of the interventricular septum away from the right ventricle and in toward the left ventricular cavity. Hemodynamic measurements were evaluated in patients with mitral stenosis to determine the underlying cause of this septal motion abnormality. There was no significant difference between Groups IIA and IIB in left atrial pressure, pulmonary arterial diastolic pressure, cardiac index, left ventricular end-diastolic pressure, right ventricular end-diastolic pressure or the ratio of left to right ventricular end-diastolic pressures. Mitral valve area calculated by both the Gorlin formula and cross-sectional echocardiographic measurement was significantly smaller in patients with greater septal motion abnormality (2.0 ± 0.9 versus 1.1 ± 0.4 cm 2 [mean ± standard error of the mean], P < 0.025) and (3.6 ± 1.4 versus 1.6 ± 0.5 cm 2, P < 0.001), respectively. In addition, calculation of rate of left ventricular filling from both the M mode echocardiogram and left ventricular cineangiogram demonstrated a significant reduction in left ventricular initial diastolic filling in Group IIB. These data suggest that the abnormal septal motion pattern noted in the M mode recording is due to a change in left ventricular initial diastolic shape and that this change in shape reflects inequality of initial diastolic filling of the two ventricles, producing a relative initial diastolic right ventricular volume overload.