Department of Mechanical Engineering, Biomedical Engineering Program, Tissue Mechanics Laboratory, University of Connecticut, 207 Bronwell Building, Storrs, CT 06269-3139, USA.
Ann Biomed Eng. 2010 Aug;38(8):2690-701. doi: 10.1007/s10439-010-0009-3. Epub 2010 Mar 25.
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.
经皮主动脉瓣（PAV）置换术目前正在作为一种经皮腔内替代传统开胸瓣膜手术的方法，用于治疗严重主动脉瓣狭窄患者。PAV 装置的多中心临床试验结果令人鼓舞。然而，该手术存在严重的不良事件。此外，还需要仔细研究 PAV 的长期耐久性和安全性。在本研究中，我们开发了一种薄的心包膜生物瓣模型，其具有与 PAV 相似的设计特征。我们利用该模型，通过有限元法，研究了 PAV 在静态、仅压力加载条件下的变形。通过戊二醛处理的薄牛心包（BP）和猪心包（PP）的平面双向测试，获得了 PAV 瓣叶的力学性能，并采用 Fung-弹性模型进行了特征化。模拟研究了组织厚度和各向异性对瓣膜变形和应力分布的影响。结果表明，在交界处附近出现了峰值应力和应变。随着瓣叶组织厚度的增加，峰值最大主应力（MPS）降低，BP 和 PP 的平均厚度分别降低了 36%和 59%。BP 瓣叶的 PAV 峰值 MPS 低于 PP 瓣叶。此外，瓣叶材料方向对 PAV 的峰值 MPS 有显著影响。
