MICROMECHANICS OF THE AORTIC VALVE

描述：（改编自研究者摘要）生物瓣膜心脏 阀门已被证明是成功的，在短期内，但继续有 长期耐久性差。 尽管我们付出了巨大的努力 进入新的心脏瓣膜设计，新的瓣膜似乎只是稍微多一点， 比旧的设计更耐用。 此外，它们的最终耐久性将需要 再过十年才能确认 部分问题在于缺乏一个 对理想生物心脏瓣膜定义的一般理解。 我们知道生物瓣膜在10到20年内就会失效， 可以持续80年，打开和关闭近30亿次。 以来 天然瓣膜的结构基质不知道如何修复和改造， 某些固有的结构和功能特性必须 使瓣膜具有非凡的耐久性 这项研究的主要目标是开发一种基本的 了解瓣膜组织的微观力学，特别是粘弹性 影响，因此我们可以制定瓣膜组织的本构模型， 可以预测加速加载条件下的瓣膜应力。 等 为了进行严格控制的耐久性试验， 可以确定生物人工心脏瓣膜的疲劳极限。 在 在此研究过程中，我们还将获得材料试验数据， 用于比较和对比天然和生物假体的力学 心脏瓣膜 这些信息将使更适当的工程 分析现有的生物人工心脏瓣膜， 设计和材料可以被识别和纠正。 像这样的数据是 这对于将阀门设计和测试从经验过程提升到 一种控制良好的工程方法。 这项研究的具体目标是： * 确定纤维瘤和心室的自然前负荷， 定义新鲜瓣叶伸长期间的载荷分担过程 和戊二醛固定的瓣膜。 * 绘制出新鲜的和 戊二醛处理的猪主动脉瓣叶。 * 制定尽量减少材料试验数据可变性的方法 和 制定标准化材料测试。 * 表征和比较猪和人主动脉的力学 瓣膜组织 * 表征心脏瓣膜组织的粘弹性响应， 基于Fung的准线性理论建立粘弹性模型 粘弹性 通过对材料试验数据的系统分析， 在这项研究中，我们的目标是更深入地了解 主动脉瓣组织功能，并表征现有的缺陷 生物假体组织 这些信息将构成设计的基础 新的，更耐用的，合成的和生物工程的心脏瓣膜替代品。

DESCRIPTION: (Adapted from investigator's abstract) Bioprosthetic heart valves have proven to be successful in the short term, but continue to have poor long-term durability. Even though considerable effort has been put into new heart valve designs, the new valves appear to be only slightly more durable than the old designs. Moreover, their ultimate durability will take another decade to confirm. Part of the problem lies in the lack of a general understanding of what defines the ideal bioprosthetic heart valve. We know that bioprostheses fail in 10 to 20 years while the natural valve can last 8 decades, opening and closing almost 3 billion times. Since the structural matrix of natural valves is not known to repair and remodel, certain inherent structural and functional characteristics must be responsible for the valve's remarkable durability. The broad objectives of this research are to develop a fundamental understandingof valve tissue micromechanics, particularly the viscoelastic effect, so that we can formulate constitutive models of valve tissues that can predict valve stresses under accelerated loading conditions. Such information will be required to carry out well controlled durability tests that can determine the fatigue limit of bioprosthetic heart valves. In the course of this research, we will also obtain material test data that can be used to compare and contrast the mechanics of natural and bioprosthetic heart valves. This information will enable a more proper engineering analysis of existing bioprosthetic heart valves, so the deficiencies in design and materials can be identified and corrected. Data such as this is critical to elevating valve design and testing from an empirical process to a well controlled engineering method. The specific aims of this study are: *Determine the natural preload of the fibrosa and ventricularis, and define the process of load sharing during leaflet elongation of fresh and glutaraldehyde-fixed valves. *Map out the patterns of biaxial strain in fresh and glutaraldehyde-treated porcine aortic valve leaflets. *Develop means of minimizing the variability of materials test data and develop standardized material tests. *Characterize and compare the mechanics of porcine and human aortic valve tissues. *Characterize the viscoelastic response of heart valve tissues and develop a viscoelastic model based on Fung's theory of quasi-linear viscoelasticity. Through a systematic analysis of the material test data that we propose to obtain in this study, we aim to develop a much deeper understanding of aortic valve tissue function, and characterize the deficiencies of existing bioprosthetic tissues. Such information will form the basis for the design of new, more durable, synthetic and bioengineered heart valve substitutes.