Altered biventricular hemodynamic forces in patients with repaired tetralogy of Fallot and right ventricular volume overload because of pulmonary regurgitation

Intracardiac hemodynamic forces have been proposed to influence remodeling and be a marker of ventricular dysfunction. We aimed to quantify the hemodynamic forces in repaired tetralogy of Fallot (rToF) patients to further understand the pathophysiological mechanisms as this could be a potential marker for pulmonary valve replacement (PVR) in these patients. Patients with rToF and PR>20% (n=18) and healthy controls (n=15) underwent magnetic resonance imaging (MRI) including 4D-flow. A subset of patients (n=8) underwent PVR and MRI after surgery. Time-resolved hemodynamic forces were quantified using 4D-flow data and indexed to ventricular volume. Patients had higher systolic and diastolic left ventricular (LV) hemodynamic forces compared to controls in the lateral-septal/LVOT (p=0.011; p=0.0031) and inferior-anterior (p<0.0001; p<0.0001) directions, which are forces not aligned with blood flow. Forces did not change after PVR. Patients had higher RV diastolic forces compared to controls in the diaphragm-RVOT (p<0.001) and apical-basal (p=0.0017) directions. After PVR RV systolic forces in the diaphragm-RVOT direction decreased (p=0.039) to lower levels than in controls (p=0.0064). RV diastolic forces decreased in all directions (p=0.0078; p=0.0078; p=0.039) but were still higher than in controls in diaphragm-RVOT direction (p=0.046). In conclusion, patients with rToF and PR had LV hemodynamic forces less aligned with the intraventricular blood flow compared to controls and higher diastolic RV forces along the regurgitant flow direction in the RVOT and that of tricuspid inflow. Remaining force differences in LV and RV after PVR suggest that biventricular pumping does not normalize after surgery.