In vitro comparison of steady and pulsatile flow characteristics of jellyfish heart valve
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In examining the hydrodynamic performance of artificial heart valves in vitro, experiments are carried out under either steady or pulsatile flow conditions. Steady flow experiments are simple to set up and analysis of the data is also simple; however, their validity and accuracy have been questioned. In this study, the flow characteristics of jellyfish valves are evaluated and analyzed for steady and pulsatile flow conditions. The analysis is given in terms of velocity and shear stress distributions for a cardiac flow rate of 4.5l/min, and the corresponding steady flow rate is measured at two locations, 0.5D and 1D downstream of the valve face (D being the diameter of the pipe). At the 0.5D location, the velocity profile results obtained for both flow conditions indicated that jetting flow occurred close to the wall, and flow reversal as well as stagnation zones occurred in the core of the valve chamber. These phenomena were also evident in the shear stress profiles for both pulsatile and steady flow conditions. At this location, the maximum difference between the steady and pulsatile values of peak velocity is about 18%. However, the maximum difference between the peak shear stresses was in the range of 5%–7%. At the 1D location, the flow characteristics observed under both the pulsatile and steady flow conditions were almost identical, with a maximum difference between the peak values of less than 4%. From the data presented here, it can be stated that, at least in the initial optimization of the valve hemodynamic performance, the steady hydrodynamic evaluation of the valve could be an effective tool for analyzing the flow characteristics.
Key wordsProsthetic valve Aortic valves Steady flow Pulsatile flow Jellyfish heart valve
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- 4.Einav S, Stolero D, Avidor JM, Elad D, Talbot L. LDA evaluation of wall shear stress distribution along the cusp of a tri-leaflet prosthetic heart valve. Proc 4th Int Symp on Application of Laser Anemometry to Fluid Mechanics. Lisbon, Portugal: 1988;7.21.1–3Google Scholar
- 5.Baldwin JT, Tarbell JM. Mean velocities and Reynolds stresses within regurgitant jets produced by tilting disc valves. Trans Am Soc Artif Int Organs 1991;37:M348-M349Google Scholar
- 10.Umezu M, Nugent AH, Ye C-X, Chang VP. Hydrodynamic performance of the St. Vincent valve: its suitability for use in artifical hearts. In: Bodnar A, (ed) Surgery for heart disease. London: London University Press, 1988:540–547Google Scholar
- 11.Baldwin JT, Tarbell JM. Mean velocities and Reynolds stresses within regurgitant jets produced by tilting disc valves. Trans Am Soc Artif Int Organs 1991;37:M348-M349Google Scholar
- 12.Teijeira FJ, Mikhail AA. Cardiac valve replacement with mechanical prosthesis: current status and trends. In: Hwang et al. (eds) Advances in cardiovascular engineering. New York: Plenum 1992;197–226Google Scholar
- 15.Imachi K, Mabuchi K, Chinzei T, Abe Y, Imanishi K, Yonezawa T, Macda K. In vitro and in vivo evaluation of a jellyfish valve for practical use. Trans Am Soc Artif Int Organs 1989;35:298–301Google Scholar
- 21.Akutsu T, Winona F, Modi VJ. Steady and pulsatile flow field comparison of several prosthetic heart valves inside the simulated left ventricle using two-component LDA system. Waseda International Congress of Modelling and Simulation Technology for Artificial Organs. Tokyo: Shinjuku 1996, August 1–3Google Scholar