Assessment of Pulmonary Regurgitation Severity in Tetralogy of Fallot Total Correction: Comparison Between Doppler Echocardiography and Cardiac MRI

Background: Pulmonary regurgitation is a common finding in patients after tetralogy of Fallot total correction (TFTC). Right ventricular enlargement and dysfunction have been ascribed to pulmonary insufficiency (PI), which is an important issue in the follow-up of patients with TFTC. We sought to compare PI measured by echocardiography with data provided by cardiac magnetic resonance imaging (CMR). Methods: We studied 155 selected patients (91 male; median age = 25.65 y, range = 15–55 y) after TFTC. To quantify the pulmonary regurgitant fraction (PRF) by CMR, we performed flow velocity mapping. On Doppler echocardiography, the length, width, and localization of the regurgitant flow, no-flow time, and pressure half-time were measured. The severity of PI on echocardiography was categorized as nonsignificant and significant and was thereafter compared to the data obtained by CMR. Results: In all 155 patients, the measurement of the flow and volume was possible by CMR, and the measurement of PI was possible by Doppler echocardiography. The mean PRF, as determined by CMR, was 33% ± 16.4%. Pulmonary regurgitation has been reported to be a causative factor in right ventricular volume enlargement. A PRF > 20% was considered significant and was compared with echocardiographic parameters and also right ventricular size and function and other indices resulted from CMR. The regression analysis showed a significant correlation between PI severity on CMR and right ventricular enlargement on MRI at end diastole (r = 0.746; P < 0.001) and also at end systole (r = 0.71; P < 0.05). Conclusions: There was no significant correlation between right ventricular ejection fraction and PI severity on CMR (r=0.553; P=0.45). On echocardiography, the semiquantitative estimation of pulmonary regurgitation showed that there were 26 patients with mild-tomoderate PI and 99 patients with severe PI. A right ventricular end-diastolic volume index (RVEDVI) of 121 mL/m² was 87% sensitive and 54% specific for severe PI, and an RVEDVI of 180 mL/m² was 90% specific for severe PI.