Optimizing Epicardial Restraint and Reinforcement Following Myocardial Infarction: Moving Towards Localized, Biomimetic, and Multitherapeutic Options

Abstract

The mechanical reinforcement of the ventricular wall after a myocardial infarction has been shown to modulate and attenuate negative remodeling that can lead to heart failure. Strategies include wraps, meshes, cardiac patches, or fluid-filled bladders. Here, we review the literature describing these strategies in the two broad categories of global restraint and local reinforcement. We further subdivide the global restraint category into biventricular and univentricular support. We discuss efforts to optimize devices in each of these categories, particularly in the last five years. These include adding functionality, biomimicry, and adjustability. We also discuss computational models of these strategies, and how they can be used to predict the reduction of stresses in the heart muscle wall. We discuss the range of timing of intervention that has been reported. Finally, we give a perspective on how novel fabrication technologies, imaging techniques, and computational models could potentially enhance these therapeutic strategies.

Keywords: biomimetics; infarct reinforcement; ventricular restraint.

Figure 1

Visual representation of types of epicardial restraint and reinforcement devices including global restrain strategies (both ventricles and left ventricle (LV) only) and local reinforcement (infarct only). Images modified and reprinted from [8,11,12,13,14,15,16,17,18,19] with permission from Elsevier, Springer, Wolters Kluwer Health, Inc., and Mary Ann Liebert, Inc., respectively. PEGSDA: Poly(ethylene glycol) sebacate diacrylate.

Figure 2

Finite element analysis (FEA)of ventricular support. (A) Three-dimensional FEA mesh of a dilated canine left ventricle (LV) in the unloaded state with a cross-sectional view of the interior cavity and wall (modified and reprinted from [51] with permission from Elsevier). (B) Biventricular FEA model with LV in red and right ventricle (RV) in grey (yellow lines are fully constrained). The green shell elements represent the Acorn cardiac support device (white lines on outside represent fiber orientations). Modified and reprinted from [52], with permission from Elsevier. (C) The Coapsys model showing the double pad side of the device. Infarct regions are colored with red while the remote regions are colored with green, myofiber stress at end systole in the virtual Coapsys model, showing a reduction of stress (in the blue area) compared to the control. Modified and reprinted from [55], with permission from Elsevier. (D) Device filling (8 mL) altered both the geometry and strain in the basal region where the device was positioned. Modified and reprinted from [18], with permission from Elsevier. (E) Maximum principal strain distribution without any wrap (left), with the epicardial mesh wrap (middle), and with the film wrap (right). Encircled area indicates RV collapse. Modified and reprinted from [37], with permission from the American Association for the Advancement of Science.

Figure 3

Side-by-side visualization of gross post-myocardial infarction (MI) left ventricular (LV) remodeling and intervention timing of epicardial devices/patches implantation. Illustration modified and reprinted from [71], with permission from Elsevier. IR: Infarct reinforcement; LVO: LV only restraint; WH: Whole heart restraint.