Key result
New trileaflet mechanical valve matches St. Jude shear stress but closes slower in mock loops.
Why the study?
Does a new trileaflet mechanical heart valve improve turbulence characteristics compared to a St. Jude Medical bileaflet valve in a mock circulatory loop?
Does a new trileaflet mechanical heart valve improve turbulence characteristics compared to a St. Jude Medical bileaflet valve in a mock circulatory loop?
A new trileaflet mechanical heart valve demonstrates similar shear stresses but slower closing velocity compared to a standard bileaflet valve in an in vitro model, which may reduce the risk of thrombosis.
May inform trileaflet valve design for hemocompatibility; leaves open whether slower closure reduces thrombosis in vivo.
Design limitations of current mechanical heart valves cause blood flow to separate at the leaflet edges and annular valve base, forming downstream vortex mixing and high turbulent shear stresses. The closing behavior of a bileaflet valve is associated with reverse flow and may lead to cavitation phenomenon. The new trileaflet (TRI) design opens similar to a physiologic valve with central flow and closes primarily due to the vortices in the aortic sinus. In this study, we measured the St. Jude Medical 27 mm and the TRI 27 mm valves in the aortic position of a pulsatile circulatory mock loop under physiologic conditions with digital particle image velocimetry (DPIV). Our results showed the major principal Reynolds shear stresses were <100 N/m2 for both valves, and turbulent viscous shear stresses were smaller than 15 N/m2. The TRI valve closed more slowly than the St. Jude Medical valve. As the magnitudes of the shear stresses were similar, the closing velocity of the valves should be considered as an important factor and might reduce the risks of thrombosis and thromboembolism.
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Li et al. (2011) studied this question. New trileaflet (TRI) 27 mm mechanical heart valve vs. St. Jude Medical 27 mm valve was evaluated on Major principal Reynolds shear stresses and turbulent viscous shear stresses. The new trileaflet mechanical heart valve demonstrated similar major principal Reynolds shear stresses (<100 N/m2) to the St. Jude Medical valve but closed more slowly in a pulsatile mock loop.
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