Abstract 9950: Right Ventricular Hemodynamic Forces: Linking Pulmonary Insufficiency to Wall Motion in Repaired Tetralogy of Fallot Patients

Abstract

Introduction: Patients with repaired Tetralogy of Fallot (rTOF) will develop right ventricle (RV) dysfunction from chronic pulmonary insufficiency (PI). Cardiac magnetic resonance (CMR) biomarkers informs timing of pulmonary valve replacement (PVR), but do not clarify the direct impact of PI on myocardial biomechanics. 4D flow studies have shown that RV hemodynamic forces (HDF) are altered in rTOF. In this study, we derived HDF in rTOF, exclusively using RV wall motion from conventional cine. Methods: This was a retrospective study using CMR of rTOF patients who had no PVR at time of imaging. Feature-tracking (QStrain, Medis) was used to capture RV wall motion from cine imaging. A novel diffeomorphic mapping technique was used to calculate 3D RV kinematic models (Figure 1A) and global HDF vector generated throughout the cardiac cycle. The RVOT-to-Diaphragm HDF vector was isolated for analysis. Global longitudinal strain, QRS duration and RV size/function were collected. Repeat analysis was performed on subgroup of rTOF who had subsequent PVR and follow-up CMR. Results: 44 rTOF studies (21±11 years) were included with regurgitant fraction (PR%) 33±15%, RV ejection fraction 50±5%, and RV end-diastolic volume 144±37 mL/m 2 . PR% correlated with RVOT-to-Diaphragm HDF vector in diastole (Figure 1B). Higher diastolic:systolic HDF ratio correlated with lower RV ejection fraction (R = -0.31, p = 0.04), lower global longitudinal strain (R = -0.38, p = 0.009), and longer QRS duration (R = 0.44, p = 0.004). 9 rTOF patients had follow-up CMR after PVR and demonstrated decrease in RVOT-to-Diaphragm HDF (Figure 1C). Conclusions: PI in rTOF patients is correlated to diastolic HDF exerted along the direction of the RVOT. Diastolic HDF correlates with RV dysfunction in rTOF patients, and as a global parameter can be captured by RV wall motion without the need to analyze 4D flow details. HDF is a potential biomarker that may provide early detection of RV dysfunction and inform PVR timing.