Pulmonary Perfusion Asymmetry in Patients after Repair of Tetralogy of Fallot: A 4D Flow MRI-Based Study

Background: Repaired Tetralogy of Fallot (rTOF) patients may have residual lesions such as main (MPA) and branch pulmonary artery stenosis (BPAS). While MPA is well studied, few data are available on BPAS in rTOF. We aimed to describe perfusion a large paediatric cohort rTOF its impact right ventricular outflow-tract hemodynamics using 4D flow CMR. Methods: 130 consecutive (mean age at CMR 14.3 ± 4.6 years) were retrospectively reviewed. 96 had transannular patch without valve preservation while 34 conserved annulus or valved conduit. A blood ratio (right (RPA)/left (LPA)) between 0.75 1.56 was considered normal. Results: Asymmetric present 59/130 (45%), with 54/59 (91%) having left lung hypoperfusion (blood >1.56). RPA/LPA the whole independently associated LPA Z-score (−0.053, p = 0.007), RPA regurgitant fraction (RF) (0.013, 0.011) previous stenting (0.648, 0.004). Decreasing % (and conversely increasing perfusion) significantly higher diameter (−0.06, 0.007). On multivariate analysis, RF (0.48,