EXPERIMENTAL VALIDATION OF SAPIEN TRANSCATHETER HEART VALVE FEA MODELS

摘要

The Edwards SAPIEN transcatheter heart valve (Figure 1) is designed for heart valve replacement in patients with severe aortic stenosis without open-heart surgery. Physiological FEA analyses have been performed to provide an assessment of the fracture and fatigue resistance of the device during deployment and operation. The present study validates FEA frame models by comparing the crimping behavior of the FEA models with the results of crimping experiments. Experimental validation is an essential verification and validation step in establishing the credibility of computational modeling and simulation [1, 2]. Finite element analysis (FEA) models for the Edwards SAPIEN transcatheter heart valve frames were created to assess the structural integrity and durability of the frame, in conjunction with a number of accelerated reliability tests. When a SAPIEN valve is prepared for delivery, the valve is reduced in diameter onto a delivery catheter using a radial force fixture called a crimper. Specifically, the frame deflects elastically at the beginning of crimping, while later the struts experience large displacements and substantial plastic deformation to achieve the desired diameter reduction. This crimping step includes all the representative deformation modes encountered during the full physiological FEA simulation. Therefore, a rigorous physical crimping experiment was developed to validate the FEA models, encompassing the full range of elastic and plastic deformation experienced during the physiological simulations. Specifically, crimping experiments were conducted using a radial force test system to compare the measured structural response of the frame to a FEA simulation of the same crimping experiments. An illustration of the crimping experiment and simulation is shown in Figure 2. The results of the experiment were compared with the elastic and plastic predictions of the FEA models both qualitatively and quantitatively.