Key result
Turbulence past a bileaflet mechanical heart valve was significantly lower in an anatomical aortic model compared to an axisymmetric model, and was minimized when aligned parallel to aortic curvature.
In vitro modeling demonstrates that implanting a bileaflet mechanical heart valve with its line of symmetry parallel to the plane of aorta curvature minimizes turbulence and viscous stresses while optimizing coronary flow.
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Valve orientation parallel to aortic curvature may minimize turbulence in mechanical valves; hypothesis-generating in vitro finding requiring clinical validation before practice change.
The objective of this research is to experimentally investigate the flow characteristics past a bileaflet mechanical heart valve (BMHV) in an anatomical model of the aorta. The measurements were made within a mock circulation loop that produced physiological pressure and flow conditions of the aorta. The velocity was measured upstream and downstream of the valve at single points using laser Doppler velocimetry and on planes using planar particle image velocimetry. Viscous and turbulent stresses were evaluated as indicators of potential blood damage. Measurements were first made with a BMHV mounted at the inlet of an axisymmetric channel, which was similar in geometry to channels previously used, and then with the BMHV mounted at the inlet of an anatomical model of the aorta. By comparing these results, the effects of the anatomical shape of the aorta on the flow past the valve were determined. It was found that the level of turbulence past the valve was significantly greater in the axisymmetric model and that the shape of the anatomical aortic sinus, in particular, was effective in reducing turbulence. Additionally, measurements with the valve mounted in three orientations at the inlet of the anatomical aorta showed that the turbulence and the viscous stresses past the valve were lower when the valve was positioned such that its line of symmetry was parallel with the plane of aorta curvature than when it was normal to it. It was further found that flow in the right coronary artery was highest when the valve was positioned with its central orifice aligned with the opening to this artery. The results of this research may be used to assist surgeons in choosing the best implantation orientation of a BMHV.
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Laura Haya (2015) studied this question. Bileaflet mechanical heart valve in an anatomical model of the aorta vs. Axisymmetric channel model was evaluated on Flow characteristics (velocity, viscous and turbulent stresses). Turbulence past a bileaflet mechanical heart valve was significantly lower in an anatomical aortic model compared to an axisymmetric model, and was minimized when aligned parallel to aortic curvature.
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