In vitro assessment of bioprosthetic valve performance in healthy and diseased right ventricular outflow tracts using magnetic resonance velocimetry

The congenital heart defect Tetralogy of Fallot (ToF) affects 1 in every 2500 newborns annually and requires surgical repair of the right ventricular outflow tract (RVOT) and subsequent placement of an artificial pulmonary valve. The longevity of these valves is highly variable and complications from ToF lead to large disparities in RVOT anatomy among patients. This work aims to assess the performance of bioprosthetic pulmonary valves in healthy and diseased RVOT geometries using magnetic resonance velocimetry. Two 3D-printed geometries were analyzed: an idealized case based on healthy subjects aged 11 to 13 and a diseased case with a 150% dilation in vessel diameter downstream of the valve. Each geometry was studied with two valve orientations: one with a valve leaflet opening posterior, which is the native pulmonary valve position, and one with a valve leaflet opening anterior. Flow features, including vortex formation and stagnation regions, are shown to be drastically different between the RVOT geometries and valve orientations. For example, in the diseased geometry, changing the valve orientation alters the jet angle at systole by 20 degrees and reduces recirculating flow around the valve throughout the cardiac cycle.