Evaluation Technique for Bileaflet Mechanical Valves
Tanya Shipkowitz PhD, Jeffrey Ambrus PhD, James Kurk MS, Kosala Wickramasinghe MS

The design performance of ATS and St. Jude Medical (SJM) bileaflet mechanical heart valves was evaluated with a combination of analysis techniques which included particle image velocimetry (PIV), computational fluid dynamics (CFD) and video analysis. Valves were analyzed by looking at leaflet opening angle, velocity profiles, pressure contours and resultant leaflet moments. The incomplete opening angle of the ATS leaflets was also studied. Results showed that the pressure field across the ATS valve produced a moment causing the valve to reach equilibrium at an opening angle of ~75° instead of the intended 85°. Additionally, ATS leaflets in the CFD model opened to the full 85° when the orifice height was increased on the outflow side. The SJM valve opened fully, and produced uniform jets through the orifice and leaflets. From the techniques utilized for evaluating valves, it was learned that leaflet opening angle is affected by the position and pressure distribution across the leaflets, leaflet exposure and orifice height.