Turbulence Characteristics Downstream of a New Trileaflet Mechanical Heart Valve

Abstract

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.

Analytical approach on leaflet flutter on biological prosthetic heart valves

“…The authors relied on aeronautical theories, making parallels with a wing airfoil and the shape of a leaflet of a bileaflet, and oscillating disk prosthetic valves. For both types of prostheses, the critical speed values found were well above the peak systolic velocity of arterial blood, though flutter in mechanical valves has been previously been noted [14,27].…”

Hemodynamic Performance of Dysfunctional Prosthetic Heart Valve with the Concomitant Presence of Subaortic Stenosis: In Silico Study

“…Regardless of the level of disease severity, the conventional aortic sinus vortex was available and did not relocate itself, but instead the strength and the size of the vortex was proportional to the level of both valve dysfunction and subaortic stenosis. Valve dysfunction and subaortic stenosis were strongly associated with a greater presence of recirculation zones downstream of the BMHV, and also were associated with late dissipation for such zones [ 45 ].…”

An in vitro investigation into the hemodynamic effects of orifice geometry and position on left ventricular vortex formation and turbulence intensity

“…The maximum turbulent viscous shear stress (TVSS) levels experienced by the red blood cells occurs at regions in the flow where the measured Kolmogorov length scale (KLS) is at its smallest. Both TVSS and KLS are employed as parameters in prior hemodynamic studies to gauge the magnitude of potential blood damage induced by the flow through artificial valves 35,36 . Since the KLS and red blood cells are both at the micron scale, it has been postulated that KLS and TVSS can be indicators of potential blood damage, as energy transferred from the integral scale are eventually dissipated at the KLS 37,38 .…”

“…Both TVSS and KLS are employed as parameters in prior hemodynamic studies to gauge the magnitude of potential blood damage induced by the flow through artificial valves. 35,36 Since the KLS and red blood cells are both at the micron scale, it has been postulated that KLS and TVSS can be indicators of potential blood damage, as energy transferred from the integral scale are eventually dissipated at the KLS. 37,38 Our experimental results from this study show no significant difference in the minimum KLS and its corresponding maximum TVSS levels between all four orifice configurations ( Table 3).…”