Right Ventricular Restrictive Physiology Is Associated With Right Ventricular Direct Flow From 4D Flow CMR.

BACKGROUND

Right ventricular restrictive physiology (RVRP) is a common occurrence in repaired tetralogy of Fallot (rTOF). The relationship of RVRP with biventricular blood flow components and kinetic energy (KE) from 4-dimensional (4D) flow cardiovascular magnetic resonance (CMR) is unclear.

OBJECTIVES

The purpose of this study was to investigate the association of 4D flow CMR parameters with RVRP in rTOF patients.

METHODS

A total of 103 rTOF patients and 62 age and sex-matched healthy control subjects were prospectively recruited. All participants underwent CMR (cine, 2-dimensional phase-contrast, and 4D flow sequences), and cardiopulmonary exercise test in adult populations. RVRP was identified from pulmonary artery flow curve using 2-dimensional phase-contrast images. Biventricular flow components (direct flow, retained inflow, delayed ejection flow, and residual volume) and KE parameters normalized to end-diastolic volume (KEiEDV) were analyzed encompassing global, peak systolic, average systolic, average diastolic, peak E-wave, and peak A-wave.

RESULTS

Compared with control subjects, rTOF patients had significantly lower RV direct flow and higher RV residual volume (both P < 0.001). All RV KEiEDV parameters, except peak A-wave, were higher in rTOF patients. In rTOF patients, 70 of 103 (68%) had RVRP, with increasing RV direct flow (27% vs 20%; P = 0.002) and RV peak E-wave KEiEDV (28.4 vs 20.7μJ/mL; P = 0.015) and decreasing RV residual volume (37% vs 42%; P = 0.039) than rTOF without RVRP. Exercise capacity was impaired in rTOF, although comparable between RVRP subgroups. Multivariable analysis revealed RV direct flow was an independent predictor of RVRP (OR: 1.158; 95% CI: 1.074-1.249; P < 0.001).

CONCLUSIONS

RVRP is associated with dilated RV, higher pulmonary regurgitation, and higher RV direct flow. (Integrated Computational modeling of Right Heart Mechanics and Blood Flow Dynamics in Congenital Heart Disease; NCT03217240).