AI Article Synopsis
- Recent studies indicate that hemolysis in mechanical heart valves (MHVs) may be linked to viscous dissipative stresses rather than just turbulent Reynolds stresses.
- The research focused on the St. Jude Medical 27 mm valve in a pulse simulation, utilizing particle image velocimetry (PIV) to analyze fluid dynamics under physiological conditions.
- Findings revealed that while Reynolds stresses could reach 80 N/m2 during the cardiac cycle, the viscous stresses were significantly lower (under 12 N/m2), suggesting that while hemolysis risk is low, there may still be potential harm to platelets that warrants additional investigation.
Article Abstract
Among the clinical complications of mechanical heart valves (MHVs), hemolysis was previously thought to result from Reynolds stresses in turbulent flows. A more recent hypothesis suggests viscous dissipative stresses at spatial scales similar in size to red blood cells may be related to hemolysis in MHVs, but the resolution of current instrumentation is insufficient to measure the smallest eddy sizes. We studied the St. Jude Medical (SJM) 27 mm valve in the aortic position of a pulsatile circulatory mock loop under physiologic conditions with particle image velocimetry (PIV). Assuming a dynamic equilibrium assumption between the resolved and sub-grid-scale (SGS) energy flux, the SGS energy flux was calculated from the strain rate tensor computed from the resolved velocity fields and the SGS stress was determined by the Smagorinsky model, from which the turbulence dissipation rate and then the viscous dissipative stresses were estimated. Our results showed Reynolds stresses up to 80 N/m2 throughout the cardiac cycle, and viscous dissipative stresses below 12 N/m2. The viscous dissipative stresses remain far below the threshold of red blood cell hemolysis, but could potentially damage platelets, implying the need for further study in the phenomenon of MHV hemolytic complications.
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| http://dx.doi.org/10.1007/s10439-009-9867-y | DOI Listing |
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