Optimization of the biological valve appliance prosthetic heart valve

Abstract

Highlights. With the use of numerical optimization algorithms, it is possible to qualitatively improve the performance (closing) of the leaflet apparatus of the heart valve prosthesis. Changing the length of the free edge of the lealflet of the prosthesis does not reduce the von Misess stress amplitude and does not change the nature of its distribution on the diagrams.Aim. Numerical study of the stress-strain state of a clinical heart valve prosthesis from the point of view of the impact of physiological loads and determination of ways to optimize the geometry of the biological leaflet apparatus.Methods. The object of study was a three-dimensional model of the UniLine (NeoCor, Russia) clinical prosthesis of the heart valve, size 23 mm, as well as four modifications focused on changing the length of the free edge. The study was carried out using the finite element method with imitation of the full cycle of operation of the leaflet apparatus under physiological conditions (pressure, heart rate). The parameters for the analysis were the qualitative and quantitative characteristics of the stress-strain state of the work of the five studied geometries.Results. It is shown that high stress areas are concentrated in two zones peripheral and free edges, regardless of the geometry. However, quantitatively, the von Mises stress amplitudes differed between the studied models. For example, the leaf shape, conventionally designated as “–10” degrees, demonstrated the smallest amplitude of this indicator relative to the original unmodified leaf model, thus reducing by a maximum of 18.8%. However, for the closed state, this model, on the contrary, showed an increase in the voltage index relative to the initial one by 8.3%. Other modification options showed similar trends.Conclusion. It is shown that despite the initial premise for optimizing the leaflet apparatus – reducing the length of the free edge and eliminating deformations of the closed state, the proposed geometry options did not significantly change the stress distribution map in the material, and also did not allow to significantly reduce the amplitudes of this parameter. Presumably, options for modifying the geometry and/or properties (rigidity, mobility) of another important component of the bioprosthesis, the support frame, which, in addition to the bearing function, provides damping of the hydrodynamic impact on the leaf due to some of its mobility, may become more promising.