Key result
St. Jude bileaflet mechanical valves produce lower turbulent stress than four other tested designs.
Why the study?
Mechanical prosthetic heart valves create complex flow patterns with elevated turbulent stresses that may contribute to thromboembolism and hemolysis, but detailed flow dynamics among different valve designs are not fully characterized.
Do different mechanical prosthetic heart valve designs differ in their fluid dynamics and turbulent stresses in an in vitro mitral position model?
Do different mechanical prosthetic heart valve designs differ in their fluid dynamics and turbulent stresses in an in vitro mitral position model?
In vitro fluid dynamics testing reveals that while all tested mechanical valves generate elevated turbulent stresses, the bileaflet St. Jude valve produces lower turbulence stress levels.
Answers are grounded in this paper and cite their sources.
Turbulence remains a concern across mechanical valves in vitro; leaves open whether design differences affect clinical hemolysis or thrombosis.
Five typical mechanical heart valves (Starr-Edwards, Björk-Shiley convexo-concave (c-c), Björk-Shiley monostrut, Bicer-Val, and St. Jude Medical) were tested in the mitral position under the pulsatile flow condition. The test program included measurements of velocity and turbulent stresses at 5 downstream locations. The study was carried out using a sophisticated cardiac simulator in conjunction with a highly sensitive 2 component laser Doppler anemometer (LDA) system. The continuous monitoring of parametric time histories revealed useful details about the complex flow and helped to establish the locations and times of the peak parameter values. Based upon the nondimensional presentation of data, the following general conclusions can be made. First, all the 5 valve designs created elevated turbulent stresses during the accelerating and peak flow phases, presenting the possibility of thromboembolism and perhaps hemolysis. Second, the difference in valve configuration seemed to affect the flow characteristics; third, the bileaflet design of the St. Jude valve appeared to create a lower turbulence stress level.
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AKUTSU et al. (1997) studied this question. Mechanical heart valves (Starr-Edwards, Björk-Shiley c-c, Björk-Shiley monostrut, Bicer-Val, St. Jude Medical) was evaluated on Velocity and turbulent stresses at 5 downstream locations. All five mechanical heart valve designs created elevated turbulent stresses during accelerating and peak flow phases, with the St. Jude bileaflet design appearing to create lower turbulence stress.
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