A model to determine the effect of collagen fiber alignment on heart function post myocardial infarction
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RESEARCH
Open Access
A model to determine the effect of collagen fiber alignment on heart function post myocardial infarction Andrew P Voorhees1 and Hai-Chao Han1,2* * Correspondence: [email protected] 1 Biomedical Engineering Program, UTSA-UTHSCSA 1 UTSA Circle, San Antonio, TX 78249, USA 2 Department of Mechanical Engineering, The University of Texas at San Antonio Biomedical Engineering Program, UTSA-UTHSCSA, 1 UTSA Circle, San Antonio, TX 78249, USA
Abstract Background: Adverse remodeling of the left ventricle (LV) following myocardial infarction (MI) leads to heart failure. Recent studies have shown that scar anisotropy is a determinant of cardiac function post-MI, however it remains unclear how changes in extracellular matrix (ECM) organization and structure contribute to changes in LV function. The objective of this study is to develop a model to identify potential mechanisms by which collagen structure and organization affect LV function post-MI. Methods: A four-region, multi-scale, cylindrical model of the post-MI LV was developed. The mechanical properties of the infarct region are governed by a constitutive equation based on the uncrimping of collagen fibers. The parameters of this constitutive equation include collagen orientation, angular dispersion, fiber stiffness, crimp angle, and density. Parametric variation of these parameters was used to elucidate the relationship between collagen properties and LV function. Results: The mathematical model of the LV revealed several factors that influenced cardiac function post-MI. LV function was maximized when collagen fibers were aligned longitudinally. Increased collagen density was also found to improve stroke volume for longitudinal alignments while increased fiber stiffness decreased stroke volume for circumferential alignments. Conclusions: The results suggest that cardiac function post-MI is best preserved through increased circumferential compliance. Further, this study identifies several collagen fiber-level mechanisms that could potentially regulate both infarct level and organ level mechanics. Improved understanding of the multi-scale relationships between the ECM and LV function will be beneficial in the design of new diagnostic and therapeutic technologies. Keywords: Cardiac mechanics, Myocardial infarction, Collagen fiber alignment, Microstructure based mechanical model, Adverse remodeling, Anisotropy
Background Coronary heart disease is the leading cause of death, accounting for over 400,000 lives in the United States every year [1]. Blockage of the diseased coronary arteries leads to myocardial infarction (MI). Post-MI, the left ventricle (LV) undergoes a complex remodeling process that results in the formation of a scar or infarct. The increased stiffness and diminished contractility of the scar reduce LV function and can lead to © 2014 Voorhees and Han; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits
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