Doppler echocardiography assessment of impaired left ventricular filling in patients with right ventricular pressure overload due to primary pulmonary hypertension

In patients with primary pulmonary hypertension, competition between the right and left ventricles for the limited pericardial space results in distortion of left ventricular geometry reflected in displacement of the ventricular septum toward the left ventricular cavity. Left ventricular shape is most dramatically deranged at end-systole and early diastole, suggesting the possibility that the distribution of left ventricular diastolic filling might be altered. To investigate this hypothesis, nine patients with primary pulmonary hypertension and nine normal individuals were studied with echocardiographic techniques. Left ventricular isovolumic relaxation time was significantly prolonged in patients with primary pulmonary hypertension by comparison with normal individuals (129 ± 36 versus 53 ± 9 ms, p < 0.005) and the fraction of the transmitral flow velocity integral occurring in the first half of diastole was significantly less than in normal individuals (38 ± 14% versus 70 ± 9%, p < 0.005). Measurement of fractional changes in short-axis left ventricular cavity area similarly demonstrated that in patients with primary pulmonary hypertension fractional early diastolic cavity expansion (32 ± 11%) was significantly less than in normal individuals (78 ± 9%, p < 0.005). In patients with primary pulmonary hypertension, the ventricular septum was abnormally flattened toward the left ventricular cavity at end-systole (normalized septal curvature 0.04 ± 0.19) and remained that way throughout early diastolic filling but returned toward normal at end-diastole (normalized septal curvature 0.68 ± 0.19, p < 0.005). Thus, in patients with primary pulmonary hypertension end-systolic and early diastolic deformation of the left ventricle by septal flattening toward the left ventricular cavity is associated with relative underfilling of the left ventricle in early diastole and redistribution of left ventricular filling into late diastole. The reliance on late diastolic filling and atrial systole to maintain left ventricular preload in primary pulmonary hypertension may have important implications for the use of vasodilators in this disease.