Right ventricular energetics and power in pulmonary regurgitation vs. stenosis using four dimensional phase contrast magnetic resonance.

OBJECTIVE: We investigated a full energetic profile of pressure and volume loaded right ventricle (RV) in porcine models by evaluating kinetic energy (KE), stroke power, power output and power loss across pulmonary valves with stenosis (PS) or with regurgitation (PR).

METHODS: Fifteen pigs (6 PS and 6 PR, 3 unoperated controls) were studied. Phase-contrast 4D-flow MRI was performed in models of PS and PR at baseline and at 10-12 weeks, in conjunction with cardiac catheterization. Phase contrast velocities over 1 cardiac cycle were registered with a dynamic mask of the RV segmented from cine images. Mean KE and KE curve profiles were measured, normalized for RV volumes and compared between groups. Right heart catheterization pressures were used to calculate RV stroke power and power output, from which pulmonary valve power loss and RV power output ratio were calculated, and compared between groups.

RESULTS: PS and PR groups had similar KE pre procedure but significant changes in KE post procedure. The PR group had higher RV power output ratio and KE (72.1% ± 11.4%; 20.6 ± 6.1) than PS group (25.6% ± 4.7%; 13.8 ± 5.0) post procedure. Volume loaded RV from PR had higher KE and power output ratio compared to pressure load from PS.

CONCLUSIONS: In porcine models of PS and PR, the RV presents altered systolic and diastolic energetic profiles. Pulmonary valve efficiency appeared to decrease in the medium term with somatic growth, with increased power loss in all groups studied, and greatly within the PS group.