Left ventricular filling characteristics in pulmonary hypertension: a new mode of ventricular interaction

Abstract

Objective: To examine the effects of pulmonary hypertension on left ventricular diastolic function and to relate the findings to possible mechanisms of interdependence between the right and left sides of the heart in ventricular disease.

Design: A retrospective and prospective analysis of echocardiographic and Doppler studies.

Setting: A tertiary referral centre for both cardiac and pulmonary disease.

Patients: 29 patients with pulmonary hypertension (12 primary pulmonary hypertension, 10 pulmonary fibrosis, five atrial septal defect (ASD), and two scleroderma) were compared with a control group of 10 patients with an enlarged right ventricle but normal pulmonary artery pressure (six ASD, one after ASD closure, one ASD and pulmonary valvotomy, one tricuspid valve endocarditis and repair, and one pulmonary fibrosis). None had clinical or echocardiographic evidence of intrinsic left ventricular disease.

Main outcome measures: M mode echocardiographic measurements were made of septal thickness, and left and right ventricular internal cavity dimensions. Doppler derived right ventricular to right atrial pressure drop, and time intervals were measured, as were isovolumic relaxation time, and Doppler left ventricular filling characteristics.

Results: The peak right ventricular to right atrial pressure gradient was (mean (SD)) 60 (16) mm Hg in pulmonary hypertensive patients, and 18 (5) mm Hg in controls. The time intervals P2 to the end of the tricuspid regurgitation, and P2 to the start of tricuspid flow were both prolonged in patients with pulmonary hypertension compared with controls (115 (60) and 120 (40) v 40 (15) and 45 (10) ms, p values less than 0.001). Pulmonary hypertensive patients commonly had a dominant A wave on the transmitral Doppler (23/29); however, all the controls had a dominant E wave. Isovolumic relaxation time of the left ventricle was prolonged in pulmonary hypertensive patients compared with controls, measured as both A2 to mitral valve opening (80 (25) v 50 (15) ms) and as A2 to the start of mitral flow (105 (30) v 60 (15) ms, p values less than 0.001). The delay from mitral valve opening to the start of transmitral flow was longer in patients with pulmonary hypertension (30 (15) ms) compared with controls (10 (10) ms, p less than 0.001). At the time of mitral opening there was a right ventricular to right atrial gradient of 12 (10) mm Hg in pulmonary hypertensive patients, but this was negligible in controls (0.4 (0.3) mm Hg, p less than 0.001).

Conclusions: Prolonged decline of right ventricular tension, the direct result of severe pulmonary hypertension, may appear as prolonged tricuspid regurgitation. It persists until after mitral valve opening on the left side of the heart, where events during isovolumic relaxation are disorganised, and subsequent filling is impaired. These effects are likely to be mediated through the interventricular septum, and this right-left ventricular asynchrony may represent a hitherto unrecognised mode of ventricular interaction.