The benefit of enhanced contractility in the infarct borderzone: a virtual experiment

• Published in: Frontiers in physiology 2012-01, Vol.3, p.86-86
• Main Authors: Zhang, Zhihong, Sun, Kay, Saloner, David A, Wallace, Arthur W, Ge, Liang, Baker, Anthony J, Guccione, Julius M, Ratcliffe, Mark B
• Format: Article
• Language: English
• Subjects: Borderzone; Finite Element; Myocardial Infarction; Physiology
• ISSN: 1664-042X; 1664-042X
• DOI: 10.3389/fphys.2012.00086

Contractile function in the normally perfused infarct borderzone (BZ) is depressed. However, the impact of reduced BZ contractility on left ventricular (LV) pump function is unknown. As a consequence, there have been no therapies specifically designed to improve BZ contractility. We tested the hypothesis that an improvement in borderzone contractility will improve LV pump function. From a previously reported study, magnetic resonance imaging (MRI) images with non-invasive tags were used to calculate 3D myocardial strain in five sheep 16 weeks after anteroapical myocardial infarction. Animal-specific finite element (FE) models were created using MRI data and LV pressure obtained at early diastolic filling. Analysis of borderzone function using those FE models has been previously reported. Chamber stiffness, pump function (Starling's law) and stress in the fiber, cross fiber, and circumferential directions were calculated. Animal-specific FE models were performed for three cases: (a) impaired BZ contractility (INJURED); (b) BZ-contractility fully restored (100% BZ IMPROVEMENT); or (c) BZ-contractility partially restored (50% BZ IMPROVEMENT). 100% BZ IMPROVEMENT and 50% BZ IMPROVEMENT both caused an upward shift in the Starling relationship, resulting in a large (36 and 26%) increase in stroke volume at LVP(ED) = 20 mmHg (8.0 ml, p