A three-dimensional analysis of flow in the pivot regions of an ATS bileaflet valve

Bileaflet heart valves are currently the most commonly implanted type of me chanical prosthetic valve, because of their low transvalvular pressure drop , centralised flow and durability However, in common with all mechanical he art valves, implanted bileaflet valves show an inherent tendency for blood clot formation at the valve site. Fluid dynamical phenomena associated with blood clotting are elevated blood shear stresses and regions of persistent blood recirculation, particularly when both occur together Using three-dim ensional CFD modelling, combined with enlarged scale experimental modelling , we investigated the blood flow through the ATS bileaflet valve during for ward flow, with particular attention to the leaflet pivot regions. Recircul ating regions were found both within and downstream of the valve housing ri ng. Qualitative assessment of the entire cardiac cycle suggested that recir culating blood within the housing ring will be washed away whilst the valve is closed, but as with all bileaflet valve designs recirculating blood dow nstream of the valve may have a residence time much longer than one cardiac cycle.