Key result
The experimental TAVI support frame model exceeded the material's strength limit with a von Mises stress of 991.4 MPa during crimping, requiring geometry optimization, whereas commercial models remained below the limit.
Why the study?
The stress-strain state of computer models of TAVI prosthesis support frames during crimping and shaping required assessment to serve as a foundation for developing an aortic valve prosthesis.
Finite element analysis of a novel proprietary TAVI support frame revealed excessive von Mises stress during crimping compared to commercial models, indicating a need for geometry optimization.
TAVI frame models require stress optimization before any clinical consideration; leaves open the role of validated numerical modeling in prosthesis design.
Highlights The presented numerical model of the bioprosthesis support frame for sutureless fixation needs to be optimized to reduce the amplitude of the von Mises stresses. The presented setup of numerical modeling has been validated using the study of commercial analogs. Abstract Aim. To assess the stress-strain state of three computer models of TAVI prosthesis support frames during crimping and shaping to the delivery configuration. Methods. The study included three models of stent-like support frames for balloon-expandable devices, which are intended to serve as a foundation for the subsequent development of a domestic aortic valve prosthesis: two models of commercial bioprostheses and one experimental. The objects were evaluated numerically under the conditions of stress-strain state that arises in the stent support frames, simulating two loads: crimping and shaping to the delivery configuration. The study was conducted using the numerical modeling complex Abaqus/CAE (“Dassault Systemes”, France). The key indicators for evaluation were the von Mises stress, as a strength criterion, and its distribution over the frame; the presence and proportion of elastic recoil. Results. It was shown that all samples are capable of reaching the required diameter without excessive material. A quantitative investigation of the Von Mises stress showed that commercial models display amplitudes below the material`s strength limit (892.4 and 916.8 MPa), whereas the proprietary model exceeds this limit, reaching 991.4 MPa, requiring geometry optimization. Shaping to the delivery configuration indicates that all models provide safe expansion up to 26 mm, with a Von Mises stress level in the range of 882.4–914.1 MPa, which is below the strength limit of the cobalt-chrome alloy. Moreover, we have noted heterogeneous stress distribution, with concentration in the lamella junction areas. Conclusion. Thus, it has been demonstrated that numerical modeling and the finite element method can be effectively applied to assess the stress-strain state of sutureless prostheses. Geometry optimization and further development of this project – the development of a Russian minimally invasive aortic valve prosthetic system, may contribute towards increasing the accessibility of this treatment method.
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Klyshnikov et al. (2023) studied Aortic valve prosthetics (computer models) (n=3). Experimental TAVI support frame model vs. Commercial TAVI models (Sapien XT, Sapien 3) was evaluated on von Mises stress during crimping. The experimental TAVI support frame model exceeded the material's strength limit with a von Mises stress of 991.4 MPa during crimping, requiring geometry optimization, whereas commercial models remained below the limit.
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