Quantification of Pulmonary Regurgitation After Surgical Repair of Tetralogy of Fallot Using Vector Flow Mapping

BACKGROUND: Pulmonary valvular regurgitation in postoperative patients with repaired tetralogy of Fallot (rTOF) significantly impairs exercise capacity and causes right heart failure. Quantitative evaluation of the pulmonary valvular regurgitation fraction (PRF) by cardiac magnetic resonance (CMR) is commonly used to determine the indication for surgical or catheter interventions, but less commonly using echocardiography. METHODS AND RESULTS: We retrospectively investigated the feasibility and validation of vector flow mapping (VFM) for the quantification of PRF (VFM-PRF) in 34 pediatric patients with rTOF, comparing it to CMR-derived PRF (CMR-PRF) and other qualitative or semiquantitative echocardiographic indices. Each predictive value for CMR-PRF ≥40% was assessed using receiver operating characteristic curves. VFM-PRF and CMR-PRF showed good agreement, with a correlation coefficient of 0.90 and the highest predictive value for CMR-PRF ≥40%, resulting in an area under the curve of 0.93. Other conventional echocardiographic parameters demonstrated poor predictive accuracy. CONCLUSIONS: This is the first report to demonstrate the accurate quantification of PRF by echocardiography using VFM in pediatric patients with rTOF, showing good agreement with CMR results. Particularly in children, VFM may be clinically useful in determining the indication for reintervention for pulmonary valve replacement, offering a possible alternative to CMR, which often requires deep sedation and general anesthesia.