Abstract
ObjectivesIndications 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.MethodsFifteen 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.ResultsLV 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%.ConclusionThis 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
Highlights
Repair of tetralogy of Fallot can result in pulmonary regurgitation (PR) which can cause dilatation of the right ventricle (RV), restrictive RV physiology [1], decreased exercise capacity [2] and predisposes the patient to ventricular arrhythmias and sudden death [3]
Our main findings are (1) Patients with Repair of tetralogy of Fallot (rToF) and PR with preserved left ventricular (LV) global function have decreased LV systolic peak kinetic energy (KE) compared to controls
(2) RV diastolic peak KE is increased in patients compared to controls as a result of the KE in the PR volume, but RV systolic KE is not different from controls even though flow volumes are much increased
Summary
Repair of tetralogy of Fallot (rToF) can result in pulmonary regurgitation (PR) which can cause dilatation of the right ventricle (RV), restrictive RV physiology [1], decreased exercise capacity [2] and predisposes the patient to ventricular arrhythmias and sudden death [3]. In patients with rToF, there is only one previously published study, which did not include analysis of diastolic KE [16]. To analyse the KE during diastole these flows can be separated using Lagrangian coherent structures (LCS), as previously shown and validated [17]. Turbulent kinetic energy has been used to study the RV of patients with rToF [18]. Turbulent KE is a different physical entity showing energy loss, compared to KE that reflects the work needed to accelerate intraventricular blood from rest to the velocity at each time point. The aim of this study was to evaluate ventricular kinetic energy during the entire cardiac cycle in patients with rToF with moderate or severe PR compared to controls, in order to describe the pathophysiological effects of PR on the left and the right ventricles
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