Effects of hydrogel injection on borderzone contractility post-myocardial infarction

Abstract

Injectable hydrogels are a potential therapy for mitigating adverse left ventricular (LV) remodeling after myocardial infarction (MI). Previous studies using magnetic resonance imaging (MRI) have shown that hydrogel treatment improves systolic strain in the borderzone (BZ) region surrounding the infarct. However, the corresponding contractile properties of the BZ myocardium are still unknown. The goal of the current study was to quantify the in vivo contractile properties of the BZ myocardium post-MI in an ovine model treated with an injectable hydrogel. Contractile properties were determined 8 weeks following posterolateral MI by minimizing the difference between in vivo strains and volume calculated from MRI and finite element model predicted strains and volume. This was accomplished by using a combination of MRI, catheterization, finite element modeling, and numerical optimization. Results show contractility in the BZ of animals treated with hydrogel injection was significantly higher than untreated controls. End-systolic (ES) fiber stress was also greatly reduced in the BZ of treated animals. The passive stiffness of the treated infarct region was found to be greater than the untreated control. Additionally, the wall thickness in the infarct and BZ regions was found to be significantly higher in the treated animals. Treatment with hydrogel injection significantly improved BZ function and reduced LV remodeling, via altered MI properties. These changes are linked to a reduction in the ES fiber stress in the BZ myocardium surrounding the infarct. The current results imply that injectable hydrogels could be a viable therapy for maintaining LV function post-MI.

Injectable Hydrogel-Based Nanocomposites for Cardiovascular Diseases

“…Since injectable hydrogels have proven to be a good treatment in clinical practice (Wang H. et al, 2018) while the method is also encountered with the lack of suitable injectable hydrogel materials owing to the respective characteristics of natural hydrogels or synthetic hydrogels. Therefore, the exploration of clinically appropriate injectable hydrogel materials is also one of the research priorities ( Table 1).…”

Quantification of Papillary Muscle Motion and Mitral Regurgitation After Myocardial Infarction

“…Echocardiographic examination of the mitral leaflets and left ventricular myocardium was used in early studies to investigate the role of the papillary muscles in mitral valve closure [10,22]. This group previously showed that in-vivo injected shear-thinning biomaterial significantly improved regional contractile function in the border zone and reduced LV remodeling in a cohort of Dorset sheep when compared to untreated controls [33]. The present study uses a similar animal-specific MRI-based FE model to quantify papillary muscle motion before and 8 weeks after MI in the same ovine cohort.…”

“…Each FE model simulation consisted of both a passive diastolic filling phase and an active systolic contraction phase (LS-DYNA, Livermore Software Technology Corporation). The methods used in this study to create the finite element models and the equations used to drive the model simulations were obtained from previous research [33,37,27]. The passive myocardium response was represented using a nearly incompressible, transversely isotropic, hyperelastic material defined by the following strain energy function [13,14]:…”

“…The passive material parameter C scales stress in all directions, while bf scales the fiber direction stiffness, bt scales the cross-fiber direction stiffness, and bfs scales the transverse-fiber direction stiffness. The response of the hydrogel injections in the DC group was represented using a nearly incompressible, isotropic, hyperelastic material law defined by the following strain energy function [33]:…”

The study of border zone formation in ischemic heart using electro‐chemical coupled computational model

“…LV remodeling particularly occurs at the ischemic area and the region surrounds this area, 6‐8 which is also known as the border zone and has a unique form of dysfunctional myocardium that partly composed of normal cells and severely damaged ischemic cells 9,10 . The abnormal mechanics of the border zone is due to the fact that it contains normally perfused but hypocontractile myocardium.…”