Right Ventricular Assessment in Adult Congenital Heart Disease Patients with Right Ventricle-to-Pulmonary Artery Conduits.

Background: There is little data on right ventricular (RV) remodeling patterns in complex congenital heart disease (CHD) patients with right ventricle to pulmonary artery (PA) conduits, and novel RV imaging modalities have not been explored in this population. Knowledge of the RV remodeling process is an important first step to future understanding and tracking of the RV response to pressure and volume overload in this diverse population. Three-dimensional knowledge-based reconstruction (3DKBR) derived from two-dimensional transthoracic echocardiography (TTE-3DKBR) is a novel approach to RV assessment. The aims of this study were twofold: (1) to assess the feasibility and accuracy of 3DKBR in patients with CHD with RV to PA conduits and (2) to characterize the three-dimensional shape of the RV across the spectrum of CHD with RV to PA conduits.

Methods: Seventeen patients with tetralogy of Fallot, pulmonary atresia with ventricular septal defect, or truncus arteriosus (mean age, 29 ± 8 years; 24% women) and a conduit referred for cardiac magnetic resonance imaging (CMR) were prospectively recruited and underwent TTE-3DKBR. TTE-3DKBR echocardiographic image acquisition was performed using a standard ultrasound scanner linked to a Ventripoint Medical Systems unit. The surface RV volumetric reconstruction was performed by transmitting two-dimensional data points to an online database and comparing these with a lesion-specific catalog to derive the RV reconstruction. Parameters analyzed were end-diastolic volume (EDV), end-systolic volume, and ejection fraction. Intertechnique agreement was assessed using Pearson's correlation analysis, coefficients of variation, and Bland-Altman analysis. Three-dimensional shape comparisons of RV surface reconstructions were performed via automated validation testing of CMRs from 43 patients (mean age, 30 ± 8 years; 32% women) with RV to PA conduits (tetralogy of Fallot, n = 15; pulmonary atresia, n = 19; and truncus arteriosus, n = 9) distinct from patients in the 3DKBR comparison.

Results: There was good correlation and agreement between the two modalities: EDV, R = 0.77, P = .0004; end-systolic volume, R = 0.93, P < .0001; ejection fraction, R = 0.75, P < .0005. On Bland-Altman analyses, CMR EDV was slightly larger TTE-3DKBR, while EF was slightly higher by 3DKBR. Qualitative and quantitative assessment both demonstrated RV shape diversity based on surface reconstructions.

Conclusion: This study demonstrates that TTE-3DKBR is an alternative technology that can be used to assess the RV in patients with complex CHD with a conduit. A novel method was used to compare RV shapes in this important population, and our results draw specific attention to the fact that the RV both within and outside diagnostic groups has very different unpredictable shapes and should not be treated equally. Our findings should set into motion future work focused on indices of RV shape and their impact on overall RV function and clinical outcomes, hence defining optimal timing of conduit revision, which at the current time is very unclear.