LEFT VENTRICULAR REMODELING IN AORTIC INSUFFICIENCY

介绍。在过去的九年中，我们的实验室通过评估体内心肌的收缩和舒张应力-应变关系，帮助开发和验证了临床评估心脏功能所必需的数学建模能力。本建议将这些临床工具的应用范围扩大到综合评价重度主动脉瓣功能不全相关病理性左室重构，以及主动脉瓣置换术（aortic valve replacement， AVR）后这种重构逆转的时间进程、程度、持续时间和预后意义。左心室重构及其逆转的准确表征将与大量临床重要疾病过程具有直接的临床相关性。简要研究概述。基于磁共振成像（MRI）的三维双心室几何数据集可以结合双心室负荷条件和有限元分析来构建准确的、患者特异性的心脏收缩和舒张数学（应力-应变）模型。严重主动脉功能不全的患者在手术前进行MRI扫描和置管，以确定临床表现时左心室病理性重构的程度。三维左室收缩期末期应力（有限元分析）和收缩期应变（有和没有多巴酚丁胺刺激）将被量化，并在适当的时间间隔与术后数据进行比较。手术后左室收缩期终应力的变化将反映AVR消除主动脉不全后发生的几何间隔变化（反向重塑）。AVR发生的重塑逆转的时间过程、程度和持久性将与临床结果进行分析。术前舒张材料特性的特征也将与随后的术后重塑逆转和临床结果有关。

Introduction. Over the last nine years, our laboratory has helped develop and validate the mathematical modeling capabilities that are necessary to clinically evaluate the function of the heart by assessing the systolic and diastolic stress-strain relationships of the in vivo myocardium. This proposal would extend the application of these clinical tools to the comprehensive evaluation of the pathological left ventricular (LV) remodeling associated with severe aortic valvular insufficiency and the time course, degree, durability and prognostic significance of the reversal of this remodeling that occurs after aortic valve replacement (AVR). The accurate characterization of left ventricular remodeling and its reversal would have direct clinical relevance to a large number of clinically significant disease processes. Brief Study Overview. Magnetic resonance imaging (MRI)-based, 3D biventricular geometrical data-sets can be combined with biventricular loading conditions and finite element analysis to construct accurate, patient-specific systolic and diastolic mathematical (stress-strain) models of the heart. Patients with severe aortic insufficiency will undergo MRI scanning and catheterization prior to surgery to characterize the degree of left ventricular pathological remodeling that is present upon clinical presentation. 3D LV end-systolic stress (finite element analysis) and systolic strains (with and without Dobutamine stimulation) will be quantified and compared to post-operative data obtained at appropriate intervals. The change in LV end-systolic stress following surgery will reflect the interval change in geometry (reverse remodeling) that has occurred as a result of elimination of the aortic insufficiency by AVR. The time course, degree and durability of reversal of remodeling that occurs that AVR will be analyzed with respect to clinical outcomes. Preoperative characterization of diastolic material properties will also be related to subsequent postoperative reversal of remodeling and clinical outcomes.