Longitudinal Study of Cardiac Remodelling in Rabbits Following Infarction

Abstract

Background Cardiac remodeling following myocardial infarction (MI) is a complex, dynamic process. There have been few longitudinal studies of these changes. Methods Two-dimensional transthoracic echocardiography was performed on 20 rabbits: before and 1, 2, 4, 8, and 12 weeks after MI (n=14) and twice for controls (n=6). Chronic left ventricular (LV) infarct size was histologically characterized and correlated with mechanical function. A linear mixed model was used to analyze longitudinal and infarct size related changes in LV end-systolic volume (ESV), end-diastolic volume (EDV), ejection fraction (EF), sphericity, circumferential strain, and wall motion score index (WMSI). Results Mean LV infarct size was 28.9±9.3%. After MI, rapid remodeling occurred in LVESV, LVEF, and sphericity for 2 weeks and LVEDV for 4 weeks, with slower changes afterwards. LV infarct size correlated with LVESV (r=0.76), LVEDV (r=0.71), and LVEF (r=0.69). Larger infarcts resulted in greater LVESV dilation (p=0.04) and faster LVEDV (p<0.01), LVEF (p<0.01) and sphericity (p<0.01) remodeling. Apical global circumferential strain and WMSI increased for 1 week then stabilized, regardless of infarct size, and apical global circumferential strain was correlated with apical infarction (r=0.58). Additionally, regional circumferential strain decreased in segments with severe (>80%) infarction more quickly (p<0.01) and by a greater degree (p=0.04) compared to segments with minor (<20%) infarction. Conclusions The most dynamic remodeling of cardiac function in this model occurred during the first 4 weeks, stabilizing thereafter, with changes maintained up to 12 weeks. Infarct size affected both the early rate and long-term extent of mechanical remodeling.

Association of hypercholesterolemia and cardiac function evaluated by speckle tracking echocardiography in a rabbit model

“…These results indicate that the cholesterol accumulated in the myocardium may be responsible for a reduction in myocardial strain. Similar to our study, Wang et al [ 23 ] reported a positive correlation between serum HDL levels and LVEF in human subjects with serum hypercholesterolemia even in the absence of angiographic evidence of CAD.…”

Implantation of a Poly-l-Lactide GCSF-Functionalized Scaffold in a Model of Chronic Myocardial Infarction

“…Only animals developing a left ventricular dysfunction with ejection fraction inferior to 35% gained access to the second phase. Timing for second surgery was defined according to the reported findings of stabilization of cardiac remodeling process [ 23 ] and achievement of a histological plateau in the infarcted myocardium 4 weeks after MI induction [ 24 ]. To control for potential biases arising from the use of the biomaterial, results were compared also to a nonfunctionalized, pristine PLLA patch.…”

Treatment with the CC chemokine-binding protein Evasin-4 improves post-infarction myocardial injury and survival in mice

“…Chronic ischaemia has been shown to induce adverse major structural and functional changes within the myocardium in both animal models and humans (1,2). During its evolution, cardiac remodelling during chronic ischaemia might involve several pathophysiological mechanisms (such as cardiomyocyte death, release of reactive oxygen species [ROS] and proteases, modifications of extracellular matrix, fibrosis, and inflammation), underlying postischaemic heart failure and potential arrhythmias (3,4).…”