Abstract 16393: Right Ventricular Energetics and Power in Pulmonary Regurgitation vs. Stenosis Using Four-Dimensional Phase-Contrast Magnetic Resonance

Background: We investigated kinetic energy (KE) and power efficiency in porcine models of pressure and volume loaded right ventricle (RV) using four-dimensional phase-contrast magnetic resonance imaging (4DPC-MRI). Methods: 4DPC-MRI was performed in pig models of pulmonary stenosis (PS) and pulmonary regurgitation (PR) at baseline and at 10-12 weeks of creation of the model, in conjunction with cardiac catheterization. Phase-contrast velocities were computed over 1 cardiac cycle (25 time-steps, MevisFlow and CAIPI, Fraunhofer MEVIS, Germany), with segmentation of a moving left ventricle mask based on cine images. The segmented mask was applied to the respective calculated 3D velocity vector field per time-step. Mean KE and KE curve profiles were measured, normalized for RV volumes and compared between PS and PR groups. Catheterization pressures and pressure-volume loops (Transonic Scisense Inc.) were used to calculate RV stroke work (RVSW) and stroke power. RV power efficiency was calculated as the ratio between RV power output and stroke power. Results: Eight pigs (4 PS and 4 PR) were studied. Table shows demographics, volumetry, KE and power data compared between groups. Both groups had similar KE pre-procedure but significant changes in KE post-procedure. In addition, the PR group had higher RV power efficiency and KE (87.1%±14.3%; 23.5±5.3, respectively) than PS group (21.4%±15.7%; 10.9±3.9) post-procedure. Conclusions: Volume loaded RV from PR had higher KE and power efficiency compared to pressure load from PS. These parameters represent the KE of blood in the RV and the net energy transferred into the pulmonary artery over one cardiac cycle. PS and PR groups have different RV work load, and they operate at different energy levels.