Simulated Thin Pericardial Bioprosthetic Valve Leaflet Deformation Under Static Pressure-Only Loading Conditions: Implications for Percutaneous Valves

Abstract

Percutaneous aortic valve (PAV) replacement is currently being investigated as an endovascular alternative to conventional open-chest valve surgery for patients with severe aortic stenosis. The results of multi-center clinical trials of PAV devices have been encouraging. However, there are serious adverse events associated with this procedure. Furthermore, long-term durability and safety of PAV need to be studied carefully. In this study, we developed a thin pericardial bioprosthetic valve model, which has similar design features of PAV. We utilized this model to investigate PAV deformation under static, pressure-only loading conditions using Finite Element method. Mechanical properties of PAV leaflet were obtained from planar biaxial testing of glutaraldehyde treated thin bovine pericardium (BP) and porcine pericardium (PP), and characterized by the Fung-elastic model. Simulations were performed to examine the effects of tissue thickness and anisotropy on the valve deformation and stress distribution. The results indicated peak stress and strain occurred in the vicinity of commissures. The peak maximum principal stresses (MPS) were reduced with the increase of leaflet tissue thickness, by 36% and 59% from the mean thickness to 0.35 mm for BP and PP, respectively. The PAV with BP leaflet had a lower peak MPS than that with PP leaflet. Moreover, leaflet material orientation had a significant influence on the peak MPS of PAV.

Total ellipse of the heart valve: the impact of eccentric stent distortion on the regional dynamic deformation of pericardial tissue leaflets of a transcatheter aortic valve replacement

“…This change in strain is sufficient to produce a large increase in leaflet stress, as pericardium is a nonlinear and hyperelastic material composed of collagenous fibres, which undergoes significant stiffening following fibre uncrimping and orientation to the axis of stretch. Based on the stress-strain relationship derived from previous equibiaxial testing results of thin pericardial tissue [2], an approximate increase in peak stress from 390 to 700 kPa would be expected in the leaflet in the eccentric valve at normotension due to a 2% increase in strain at the leaflet commissures.…”

“…Transcatheter aortic valve replacement (TAVRs) is a percutaneous alternative to surgical aortic valve replacement (SAVR), which is used to treat intermediate and high-risk operable patient cohorts [1][2][3]. TAVRs consist of pericardial tissue leaflets sutured to a collapsible metallic stent.…”

Simulated elliptical bioprosthetic valve deformation: Implications for asymmetric transcatheter valve deployment

“…Finite element (FE) simulation and computational fluid dynamics (CFD) simulation were performed to examine structural and fluid dynamics responses of TAVs at different configurations of distortion. Simulation results of elliptical TAVs were compared with those of a nominal circular TAV (Li and Sun, 2010).…”

“…In this study, we performed computational simulations to analyze asymmetric bioprosthetic valve deformation to understand the biomechanics involved in TAV deployment into a calcified aortic root. We utilized a thin pericardial bioprosthetic valve model that was recently developed and had similar design features as those of TAVs (Li and Sun, 2010). Degree of elliptical TAV configuration was measured from clinical images of implanted transcatheter valves.…”

Hemodynamic Impact of Transcatheter Aortic Valve Deployment Configuration

“…The geometry of a "generic" TAV has been described in detail [6]. It is a thin pericardial bioprosthetic valve with similar design features to TAVs used commercially.…”