Simulated Effects of Acute Left Ventricular Myocardial Infarction On Mitral Regurgitation in an Ovine Model.

Abstract

Development of patient specific models of LV-MV interactions in ischemic mitral regurgitation (IMR) are complicated by the substantial variability and complex etiologies, making it difficult to extract underlying mechanisms. We thus developed a detailed ovine LV-MV finite element model based for the normal and acute post-MI states. The ovine LV FEM model was first extended to incorporate a detailed MV leaflet sub-model with a functionally-equivalent CT structure. The resulting complete LV-MV model was first used to simulate the full cardiac cycle in the normal state to establish baseline responses. We then simulated regional acute infarctions of varying sizes in various known infarct anatomical locations by shutting down the local myocardial contractility, while remote regions were allowed to adjust their active contractile patterns to maintain the prescribed pressure-volume loop. Simulation results indicated that the posterobasal infarct induced the largest MV regurgitation orifice area, consistent with experimental observations. We incorporated previously reported MV leaflet pre-strains (Amini et al., Ann Biomed Eng. 2012 Jul;40(7):1455-67) in the simulations, which then resulted in excellent agreement. Extensional deformations of the posterior leaflets occurred in the posterobasal and laterobasal infarcts, while compressive deformations of anterior leaflets were observed in the anterobasal infarct. The present study is the first detailed LV-MV simulations to reveal the important role of ,V EAF;ET pre-strain For accurate model prediction, underscoring that proper accounting of residual strains is an essential part of accurate simulations of organ level function.