Regenerated Contracting Myocardium May Improve Post-Surgery Right Ventricle Function: Patch Comparison Using MRI-Based Two-Layer Anisotropic Models of Human Right and Left Ventricles

Abstract

Patients with repaired Tetralogy of Fallot (ToF), a congenital heart defect which includes a ventricular septal defect and severe right ventricular outflow obstruction, account for the majority of cases with late onset RV failure. The current surgical approach, which includes pulmonary valve replacement/insertion (PVR), has yielded mixed results. One reason for the unpredictable results is that the PVR surgery only addresses pulmonary regurgitation. New surgical options including scar tissue reduction and RV remodeling have been proposed in order to improve RV function recovery [1]. Various RV reconstruction techniques are being investigated, including patch design (materials, sizes, and shapes) and myocardium regeneration techniques which have the potential that viable myocardium may be regenerated or placed in the patch area [2,4]. Wald and Geva et al. investigated effects of regional dysfunction on global RV function in patients with repaired ToF and reported that localized dysfunction in the region of the RV outflow tract patch adversely affects global RV function and regional measures, and may have important implications for patient management [5]. Recent advances in computational modeling have made it possible for computer-simulated procedures (virtual surgery) to be used in clinical decision-making process to replace empirical and often risky clinical experimentation to examine the efficiency and suitability of various reconstructive procedures and patch design in diseased hearts [4]. In this paper, cardiac magnetic resonance imaging (CMR)-based two-layer active anisotropic models of human right and left ventricles (RV/LV) were constructed to compare three different patch materials and investigate the potential improvement of regenerated contracting myocardium on RV function after PVR surgery: Patch 1 – Dacron scaffold; Patch 2 – pericardium treated with gluteraldehyde; Patch 3 – viable contracting myocardium (not currently available but represents future direction). The 3D CMR-based RV/LV/Patch combination models were solved to obtain 3D ventricular deformation and stress/strain distributions for accurate assessment of RV mechanical conditions and function. The computational models were validated by CMR data and then used to assess the effect of patch material properties with the ultimate goal of improving recovery of RV function after surgery.