Characteristic flow of different right ventricular outflow tract morphology in repaired tetralogy of fallot patients studied by 4D-flow cardiac magnetic resonance images.
TL;DR
The tubular RVOT morphology is associated with a significantly higher local hemodynamic profile across the PV and MPA compared to the pyramidal morphology, which 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.
Abstract
Background
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).
Methods
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.
Results
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.
Conclusions
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.