Right Ventricular Diastolic Function in Children With Pulmonary Regurgitation After Repair of Tetralogy of Fallot: Volumetric Evaluation by Magnetic Resonance Velocity Mapping

Objectives. We sought to assess right ventricular diastolic function in young patients with corrected tetralogy of Fallot and pulmonary regurgitation. Background. Pulmonary regurgitation is an important problem in repair of tetralogy of Fallot. Its effects on right ventricular diastolic function in children are unknown. Methods. Nineteen children with repair of tetralogy of Fallot (mean age [±SD] 12 ± 3 years, mean age at operation 1.5 ± 1) and 12 healthy children were studied. Summation of magnetic resonance velocity mapping pulmonary and tricuspid volume flow curves provided right ventricular time–volume curves. Ventricular size was assessed with tomographic magnetic resonance imaging (MRI). Graded exercise testing was performed. Results. Systematic and random differences (mean ± SD) of velocity mapping and Doppler tricuspid time to peak velocities (peak E: 1 ± 26 ms, r = 0.43; peak A: 2 ± 11 ms, r = 0.76), E/ ratios (0.04 ± 0.5, r = 0.63) and duration of pulmonary regurgitation (20 ± 35 ms, r = 0.74) were satisfactory. In 6 patients (group I), late diastolic forward pulmonary artery flow was absent; in 13 patients (group II), this flow contributed 1% to 14% to right ventricular stroke volume. Significant differences were increased deceleration time (315 ± 91 vs. 168 ± 28 ms, p < 0.001), decreased filling fraction (44 ± 11 vs. 55 ± 16%, p = 0.02) and increased peak early filling rate (378 ± 124 vs. 286 ± 112 ml/s, p = 0.018) between control subjects and group I, and increased deceleration time (230 ± 40, p = 0.03) between control subjects and group II. Pulmonary regurgitation, ventricular size and ejection fraction did not differ significantly between patient groups. Exercise function was diminished with restrictive right ventricular physiology (p < 0.001, group II vs. control subjects). Conclusions. Impaired relaxation and restriction to filling affect diastolic right ventricular function in children with repair of tetralogy of Fallot and pulmonary regurgitation. Restrictive right ventricular physiology is associated with decreased exercise function.