Intracardiac Flow Analysis of the Right Ventricle in Pediatric Patients With Repaired Tetralogy of Fallot Using a Novel Color Doppler Velocity Reconstruction

Background: Repaired tetralogy of Fallot (RTOF) patients will develop right ventricular (RV) dysfunction from chronic pulmonary regurgitation (PR). Cardiac magnetic resonance sequences such as four-dimensional flow can demonstrate altered vorticity and flow energy loss (FEL); however, they are not as available as con-ventional echocardiography (echo). The study determined whether a novel, vendor-independent Doppler ve-locity reconstruction (DoVeR) could measure RV intracardiac flow in conventional echo of RTOF patients. The primary hypothesis was that DoVeR could detect increased vorticity and diastolic FEL in RTOF patients. Methods: Repaired tetralogy of Fallot patients with echo were retrospectively paired with age-/size-matched controls. Doppler velocity reconstruction employed the stream function-vorticity equation to approximate intra-cardiac flow fields from color Doppler. A velocity field of the right ventricle was reconstructed from the apical 4 -chamber view. Vortex strength (VS, area integral of vorticity) and FEL were derived from DoVeR. Cardiac mag-netic resonance and exercise stress parameters (performed within 1 year of echo) were collected for analysis. Results: Twenty RTOF patients and age-matched controls were included in the study. Mean regurgitant frac-tion was 40.5% +/- 7.6%, and indexed RV end-diastolic volume was 158 +/- 36 mL/m2. Repaired tetralogy of Fallot patients had higher total, mean diastolic, and peak diastolic VS (P = .0013, P = .0012, P = .0032, respec-tively) and higher total, mean diastolic, and peak diastolic body surface area-indexed FEL (P = .0016, P = .0022, P < .001, respectively). Peak diastolic indexed FEL and peak diastolic VS had weak-to-moderate negative correlation with RV ejection fraction (r = -0.52 [P = .019] and r = -0.49 [P = .030], respectively) and left ventricular ejection fraction (r = -0.47 [P = .034] and r = -0.64 [P = .002], respectively). Mean diastolic indexed FEL and VS had moderate-to-strong negative correlation with percent predicted maximal oxygen consumption (r = -0.69 [P = .012] and r = -0.75 [P = .006], respectively). Conclusions: DoVeR can detect alterations to intracardiac flow in RTOF patients from conventional color Doppler imaging. Echo-based measures of diastolic VS and FEL correlated with ventricular function. DoVeR has the potential to provide serial evaluation of abnormal flow dynamics in RTOF patients. (J Am Soc Echo-cardiogr 2023;36:644-53.)

Automated summary

The study aimed to determine whether a novel, vendor-independent Doppler velocity reconstruction (DoVeR) could measure right ventricular intracardiac flow in conventional echocardiography of repaired tetralogy of Fallot (RTOF) patients. The results showed that DoVeR could detect increased vorticity and diastolic flow energy loss (FEL) in RTOF patients, and these measures correlated with ventricular function. The importance of this study lies in the potential of DoVeR to provide serial evaluation of abnormal flow dynamics in RTOF patients.