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BACKGROUND: The effective valve orifice area of small prosthetic valves limits semilunar valve replacement, especially in pediatric patients. The Single Point Attached Commissure (SPAC) stentless valves with a tubular configuration are commercially available to overcome this limitation. However, the leaflets geometry of these valves is different from native valves. We hypothesize that a SPAC valve with modified leaflets geometry based on native valves, will have similar hemodynamics to the native valve, with better coaptation and opening than existing valves.

METHODS: Porcine pericardium was fixed to form modified geometry with deep coaptation using the mold innovated by our group based on the native valve contour. The model was constructed using silicon graft with sinuses. The valve was hand-sewn to the silicon graft at the base with a singular stitch to each commissure. Particle Image Velocimetry (PIV) was obtained with 14 sets of pictures in 1 cardiac cycle and evaluated for flow dynamics and velocity. Valve motion was captured with a video camera and compared to the valve with tubular configuration.

RESULTS: During early-mid systole, there was a steep increase in velocity up to 1m/s. In late systole, flow dynamics changed from unidirectional to non-unidirectional flow, leading to a reversal of flow and small vortexes facilitated semilunar valve closure. In early-mid diastole, the backflow coupled with larger vortexes completed the closure. PIV demonstrated similar characteristics to the native valve in PIV. No structural instability of the valve or stagnant flow around the free stitch-less space between the commissure and the base were observed. Video capturing showed larger effective valve orifice area in the modified valve compared to the valve with tubular configuration.
CONCLUSIONS: The SPAC valve with modified valve geometry is feasible and has a potential to be superior to the commercially available stentless valves.