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.
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