Right ventricular diastolic function 15 to 35 years after repair of tetralogy of Fallot. Restrictive physiology predicts superior exercise performance

Abstract

Background: We have shown previously that transient right ventricular restriction after tetralogy of Fallot repair prolongs postoperative course. This is a prospective study of right ventricular diastolic performance in late follow-up patients.

Methods and results: We studied biventricular function, using Doppler echocardiographic examination. Pulmonary arterial, tricuspid, and mitral valves and superior vena cava Doppler spectrals were obtained in 41 patients (mean age, 28.8 years), 15 to 35 years (mean, 23.6) after complete repair of tetralogy of Fallot. Patients were considered to have evidence of right ventricular restriction if antegrade diastolic flow was detected in the main pulmonary artery, coinciding with atrial systole (A wave), throughout the respiratory cycle. Exercise function was measured by graded treadmill testing with respiratory mass spectrometry. Three patients were excluded because of pulmonary outflow obstruction (Doppler gradient > 40 mm Hg) or residual intracardiac shunts. Of the 38 patients, 37 were in sinus rhythm. Twenty (52.6%) had definite evidence of restriction with an A wave in the pulmonary artery, augmented during inspiration. In all 20 cases, there was superior vena caval flow reversal with atrial systole. Both inspiratory and expiratory transtricuspid E-wave deceleration time was significantly shorter in the restrictive group (P < .003 and P < .03, respectively). All patients had Doppler evidence of pulmonary regurgitation, but its duration was shorter in the restrictive group (P < .01) during inspiration. Cardiothoracic ratio was significantly lower in the restrictive group (P < .01), suggesting less severe pulmonary regurgitation. Both restrictive and nonrestrictive groups had reduced exercise MVO2 compared with healthy age- and sex-matched control subjects, but those with restrictive physiology had significantly better maximum oxygen uptake than the nonrestrictive group (P < .001).

Conclusions: Isolated right ventricular restriction late after tetralogy of Fallot repair is common. Although it reflects abnormal hemodynamics, the A wave contributes to forward pulmonary arterial flow and shortens the duration of pulmonary regurgitation. Consequently, there is less cardiomegaly and improved exercise performance in those patients.