There are more than 300,000 heart valves implanted annually worldwide with
about 50% of them being mechanical valves. The heart valve replacement is often
a common treatment for severe valvular disease. However, valves may dysfunction
leading to adverse hemodynamic conditions. The current computational study
investigated the flow around a bileaflet mechanical heart valve at different
leaflet dysfunction levels of 0%, 50%, and 100%, and documented the relevant
flow characteristics such as vortical structures and turbulent shear stresses.
Studying the flow characteristics through these valves during their normal
operation and dysfunction can lead to better understanding of their
performance, possibly improved designs, and help identify conditions that may
increase the potential risk of blood cell damage. Results suggested that
maximum flow velocities increased with dysfunction from 2.05 to 4.49 ms-1 which
were accompanied by growing eddies and velocity fluctuations. These
fluctuations led to higher turbulent shear stresses from 90 to 800 N.m-2 as
dysfunctionality increased. These stress values exceeded the thresholds
corresponding to elevated risk of hemolysis and platelet activation. The
regions of elevated stresses were concentrated around and downstream of the
functional leaflet where high jet velocity and stronger helical structures
existed