Disturbed left and right ventricular kinetic energy in patients with repaired tetralogy of Fallot: pathophysiological insights using 4D-flow MRI.

OBJECTIVES: Indications for pulmonary valve replacement (PVR) in patients with pulmonary regurgitation (PR) after repaired tetralogy of Fallot (rToF) are debated. We aimed to compare right (RV) and left ventricular (LV) kinetic energy (KE) measured by 4D-flow magnetic resonance imaging (MRI) in patients to controls, to further understand the pathophysiological effects of PR.

METHODS: Fifteen patients with rToF with PR > 20% and 14 controls underwent MRI. Ventricular volumes and KE were quantified from cine MRI and 4D-flow, respectively. Lagrangian coherent structures were used to discriminate KE in the PR. Restrictive RV physiology was defined as end-diastolic forward flow.

RESULTS: LV systolic peak KE was lower in rToF, 2.8 ± 1.1 mJ, compared to healthy volunteers, 4.8 ± 1.1 mJ, p < 0.0001. RV diastolic peak KE was higher in rToF (7.7 ± 4.3 mJ vs 3.1 ± 1.3 mJ, p = 0.0001) and the difference most pronounced in patients with non-restrictive RV physiology. KE was primarily located in the PR volume at the time of diastolic peak KE, 64 ± 17%.

CONCLUSION: This is the first study showing disturbed KE in patients with rToF and PR, in both the RV and LV. The role of KE as a potential early marker of ventricular dysfunction to guide intervention needs to be addressed in future studies.

KEY POINTS: • Kinetic energy (KE) reflects ventricular performance • KE is a potential marker of ventricular dysfunction in Fallot patients • KE is disturbed in both ventricles in patients with tetralogy of Fallot • KE contributes to the understanding of the pathophysiology of pulmonary regurgitation • Lagrangian coherent structures enable differentiation of ventricular inflows.