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首页> 外文学位 >Characterization of tricuspid and bicuspid aortic valve hemodynamics under normal and calcified states.
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Characterization of tricuspid and bicuspid aortic valve hemodynamics under normal and calcified states.

机译：正常和钙化状态下三尖瓣和双尖瓣主动脉瓣血流动力学的特征。

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摘要

Calcific aortic valve disease (CAVD) is the most prevalent form of heart valve disease, affecting 25% of the population 65 years and older with disease progression lasting 20-30 years. It is marked by the initial thickening and stiffening of the leaflets, followed by the formation of calcific lesions within the valve leaflets. In the bicuspid aortic valve (BAV), which is the most common type of aortic valve defect and is characterized by the formation of two functional leaflets instead of three, the onset of CAVD typically occurs at an earlier age and progresses to severe stenosis much more rapidly than in the normal tricuspid aortic valve (TAV). While the etiology of CAVD has been linked to altered hemodynamics, which may be linked to altered valve geometries, alterations in hemodynamic performance due to anatomic and calcific defects have not been investigated. Therefore, the goal of this dissertation is to present a comparative in vitro assessment of the valvular flow and performance in a TAV and BAV under normal and calcified states.;Particle-image velocimetry was used to characterize the flow downstream of a model TAV, model BAV, model calcified TAV, and model calcified BAV mounted in an idealized aortic sinus geometry. Valve performance was analyzed under steady flow conditions in terms of geometric orifice area, effective orifice area, and energy loss. Comparison of valve hemodynamics was based on velocity, vorticity, viscous shear stress, and Reynolds shear stress under physiologic flow and pressure conditions.;This study found that valvular anatomy and leaflet stiffening impact large-scale flow structures, but suggested that the BAV can function and generate energy loss at a level similar to a normal valve despite its intrinsic degree of stenosis. The main difference in valve performance between the BAV and TAV was in the elevated shear stress and turbulence experienced by the BAV. Calcification of the valve also led to a similar increase in the viscous shear stress and turbulence but significant decrease in valve performance. These similarities in the hemodynamic alterations in valves with anatomic or calcific defects as compared to normal TAV hemodynamics demonstrated a positive feedback cycle, which may be linked to CAVD development and progression.
机译：钙化主动脉瓣膜疾病（CAVD）是心脏瓣膜疾病的最普遍形式，影响65岁及以上人口的25％，疾病进展持续20-30年。其特征在于小叶的最初增厚和变硬，然后在瓣膜小叶内形成钙化病变。在二尖瓣主动脉瓣（BAV）中，这是最常见的主动脉瓣缺损类型，其特征是形成了两个功能性小叶而不是三个，而CAVD的发作通常发生在较早的年龄，并发展为严重的狭窄比正常的三尖瓣主动脉瓣（TAV）更快。尽管CAVD的病因学与改变的血液动力学有关，可能与改变的瓣膜几何结构有关，但尚未研究由于解剖学和钙化缺陷引起的血液动力学性能改变。因此，本论文的目的是对正常和钙化状态下的TAV和BAV中的瓣膜血流和性能进行体外比较评估。；颗粒图像测速法用于表征模型TAV，模型下游的血流BAV，模型钙化TAV和模型钙化BAV安装在理想的主动脉窦几何结构中。在稳定流量条件下，根据几何孔口面积，有效孔口面积和能量损失对阀门性能进行了分析。瓣膜血流动力学的比较是基于生理流动和压力条件下的速度，涡度，粘性剪切应力和雷诺剪切应力。这项研究发现瓣膜解剖结构和小叶硬化会影响大规模的流动结构，但表明BAV可以发挥作用尽管其固有的狭窄程度，但仍会产生与正常瓣膜相似的能量损失。 BAV和TAV之间阀门性能的主要差异在于BAV承受的剪切应力和湍流增加。阀门的钙化也导致粘性剪切应力和湍流的增加，但是阀门性能显着下降。与正常TAV血流动力学相比，具有解剖或钙化缺损的瓣膜血流动力学改变的这些相似性显示出正反馈周期，这可能与CAVD的发生和发展有关。

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  • 作者

    Seaman, Clara Elizabeth.;

  • 作者单位

    University of Notre Dame.;

  • 授予单位 University of Notre Dame.;
  • 学科 Engineering Mechanical.;Engineering Biomedical.
  • 学位 Ph.D.
  • 年度 2014
  • 页码 187 p.
  • 总页数 187
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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