Key result
Tubular RVOT in repaired ToF is linked to higher hemodynamic profiles versus pyramidal morphology.
Why the study?
Does tubular RVOT morphology compared to pyramidal morphology alter 4D-flow hemodynamic profiles in patients with repaired tetralogy of Fallot?
Observational (n=120)
No
Does tubular RVOT morphology compared to pyramidal morphology alter 4D-flow hemodynamic profiles in patients with repaired tetralogy of Fallot?
Advanced 4D-flow CMR reveals that tubular RVOT morphology in repaired tetralogy of Fallot is associated with higher local hemodynamic load compared to pyramidal morphology, despite similar conventional imaging parameters.
Should not yet change rTOF management; extends evidence that 4D-flow CMR detects hemodynamic differences missed by conventional imaging.
Right ventricular outflow tract (RVOT) morphology may influence hemodynamics and suitability for transcatheter pulmonic valve implantation (PPVI) in patients with repaired tetralogy of Fallot (rTOF). We retrospectively analyzed 120 rTOF patients who underwent cardiovascular magnetic resonance (CMR) imaging with 4D-flow analysis. RVOT morphology was classified as tubular, pyramidal, or trapezoid, with inverted pyramidal and concave morphologies absent. Due to small numbers in minor groups, analysis focused on tubular ( n = 86) and pyramidal ( n = 22) RVOTs. Conventional CMR parameters, including ventricular volumes, function, pulmonic valve (PV) annulus size, and pulmonary regurgitation (PR), as well as 4D-flow hemodynamic parameters, were compared between groups. The tubular and pyramidal RVOT groups showed no significant differences in patient demographics, transannular patch history, long-term clinical events (arrhythmia, pulmonic valve replacement necessity), or conventional CMR measures of LV/RV volumes, function, or PR severity. However, the 4D-flow analysis revealed distinct hemodynamic profiles. The tubular RVOT group generally demonstrated a higher hemodynamic load than the pyramidal group, specifically showing higher peak velocity at the RVOT (but lower at the RPA), higher maximum magnitude wall shear stress (WSS) at the RVOT, PV, and MPA (but lower at the RPA), higher average magnitude WSS at the PV and MPA and greater average energy loss at PV. Despite similar conventional CMR findings and clinical outcomes, the tubular RVOT morphology is associated with a significantly higher local hemodynamic profile across the PV and MPA compared to the pyramidal morphology. This suggests that advanced 4D-flow parameters are more sensitive to morphological differences and may be important for risk stratification and understanding the long-term integrity of the different RVOT morphologies.
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Srivichean et al. (2026) conducted an observational in Repaired tetralogy of Fallot (rTOF) (n=120). Tubular right ventricular outflow tract (RVOT) morphology vs. Pyramidal RVOT morphology was evaluated on 4D-flow hemodynamic parameters (peak velocity, wall shear stress, and energy loss). Tubular right ventricular outflow tract morphology in repaired tetralogy of Fallot is associated with a significantly higher local hemodynamic profile across the pulmonic valve and main pulmonary artery compared to pyramidal morphology.