Evolution of Scar Mechanical Properties During Myocardial Infarct Healing in Rat

2007 ◽  
Author(s):  
Gregory M. Fomovsky ◽  
Jeffrey W. Holmes
Keyword(s):  
Myocardial Infarction ◽  
Mechanical Properties ◽  
Rat Model ◽  
Important Determinant ◽  
Myocardial Infarct ◽  
Left Ventricular ◽  
Lv Function ◽  
Large Animal ◽  
Lv Dysfunction ◽  
Infarct Healing

The mechanics of healing myocardial infarcts are an important determinant of post-infarction left ventricular (LV) function and remodeling. Large animal infarct models are well studied; healing infarct scars have been shown to be mechanically and structurally anisotropic [1], and this anisotropy may help preserve LV function during some stages of healing [2]. At the same time, it has been suggested that the rat model of myocardial infarction is more similar to humans in the range of infarct sizes and observed LV dysfunction [3]. However, in the rat model, infarct mechanics and their effect on the overall LV function have not been described so far.

scholarly journals Evolution of scar structure, mechanics, and ventricular function after myocardial infarction in the rat

2010 ◽  
Vol 298 (1) ◽  
pp. H221-H228 ◽  
Author(s):  
Gregory M. Fomovsky ◽  
Jeffrey W. Holmes
Keyword(s):  
Myocardial Infarction ◽  
Mechanical Properties ◽  
Ventricular Function ◽  
Heart Function ◽  
Systolic Pressure ◽  
Left Ventricular ◽  
Collagen Content ◽  
Lv Function ◽  
Large Animal ◽  
Large Animal Models

The mechanical properties of the healing scar are an important determinant of heart function following myocardial infarction. Yet the relationship between scar structure, scar mechanics, and ventricular function remains poorly understood, in part because no published study has tracked all of these factors simultaneously in any animal model. We therefore studied the temporal evolution of scar structure, scar mechanics, and left ventricular (LV) function in large anterior myocardial infarcts in rats. At 1, 2, 3, and 6 wk after left anterior descending coronary ligation, we examined LV function using sonomicrometry, infarct mechanical properties using biaxial mechanical testing, infarct structure using polarized light microscopy, and scar collagen content and cross-linking using biochemical assays. Healing infarcts in the rat were structurally and mechanically isotropic at all time points. Collagen content increased with time and was the primary determinant of scar mechanical properties. The presence of healing infarcts influenced systolic LV function through a rightward shift of the end-systolic pressure-volume relationship (ESPVR) that depended on infarct size, infarct collagen content, and LV dilation. We conclude that in sharp contrast to previous reports in large animal models, healing infarcts are structurally and mechanically isotropic in the standard rat model of myocardial infarction. On the basis of the regional strain patterns we observed in healing rat infarcts in this study and in healing pig infarcts in previous studies, we hypothesize that the local pattern of stretching determines collagen alignment in healing myocardial infarct scars.

Myocardial infarction with and without reperfusion in sheep: early cardiac and neurohumoral changes

2000 ◽  
Vol 98 (6) ◽  
pp. 703-711 ◽  
Author(s):  
Christopher J. CHARLES ◽  
John M. ELLIOTT ◽  
M. Gary NICHOLLS ◽  
Miriam T. RADEMAKER ◽  
Mark RICHARDS
Keyword(s):  
Myocardial Infarction ◽  
Coronary Artery ◽  
Ejection Fraction ◽  
Troponin T ◽  
Coronary Artery Occlusion ◽  
Artery Occlusion ◽  
Left Ventricular ◽  
Lv Function ◽  
Large Animal ◽  
Lv Dysfunction

There are few stable and reproducible large-animal models of chronic heart failure produced by ischaemic damage to the myocardium. Here we characterize a novel method of inducing myocardial damage in closed-chest sheep by catheter delivery of thrombogenic coils, and compare this with a newly described open-artery model of cardiac injury in sheep. Sham controls were compared with animals subjected to (a) 90 min of coronary artery occlusion/reperfusion by PTCA (percutaneous transluminal coronary angioplasty) balloon, and (b) permanent coronary artery occlusion induced by catheter delivery of thrombogenic coils (seven sheep/group). Both balloon occlusion/reperfusion and permanent coil occlusion resulted in well-defined anteroapical infarcts, as documented by ECG changes, significant rises in creatine kinase (both groups P < 0.001) and troponin-T (both groups P < 0.05), and post-mortem examination. Washout of enzymes was much more rapid in the reperfused group (P < 0.01). Infarction resulted in significant reductions in left ventricular (LV) ejection fraction (both groups P < 0.01) and regional wall abnormalities. Ejection fraction 7 days post-coil (21.3±4.2%) was significantly lower (P < 0.01) than that 7 days post-balloon (38.8±4.5%). Coil-induced infarction was associated with acutely reduced arterial pressure (P < 0.05), and increases in heart rate (P < 0.05), atrial pressures (P < 0.05), plasma brain natriuretic peptide levels (P < 0.05) and adrenaline levels (P < 0.05). Rises seen in plasma endothelin levels in sham controls were blunted in the coil group (P < 0.001). Haemodynamic changes were less marked in the balloon group. In conclusion, restriction of coronary artery occlusion to 90 min results in infarction, but less LV dysfunction with reduced early remodelling, compared with permanent occlusion. Acute changes in biochemical markers, haemodynamics, neurohormones and LV function confirm that these are excellent models of open- and closed-artery myocardial infarction leading to asymptomatic LV dysfunction.

scholarly journals Effect of cardiosphere-derived cells on segmental myocardial function after myocardial infarction: ALLSTAR randomised clinical trial

Open Heart ◽  
2021 ◽  
Vol 8 (2) ◽  
pp. e001614
Author(s):  
Mohammad R Ostovaneh ◽  
Raj R Makkar ◽  
Bharath Ambale-Venkatesh ◽  
Deborah Ascheim ◽  
Tarun Chakravarty ◽  
...  
Keyword(s):  
Myocardial Infarction ◽  
Clinical Trial ◽  
Myocardial Function ◽  
Randomised Clinical Trial ◽  
Scar Tissue ◽  
Left Ventricular ◽  
Lv Function ◽  
Cardiac Events ◽  
Lv Dysfunction ◽  
Registration Number

BackgroundMost cell therapy trials failed to show an improvement in global left ventricular (LV) function measures after myocardial infarction (MI). Myocardial segments are heterogeneously impacted by MI. Global LV function indices are not able to detect the small treatment effects on segmental myocardial function which may have prognostic implications for cardiac events. We aimed to test the efficacy of allogeneic cardiosphere-derived cells (CDCs) for improving regional myocardial function and contractility.MethodsIn this exploratory analysis of a randomised clinical trial, 142 patients with post-MI with LVEF <45% and 15% or greater LV scar size were randomised in 2:1 ratio to receive intracoronary infusion of allogenic CDCs or placebo, respectively. Change in segmental myocardial circumferential strain (Ecc) by MRI from baseline to 6 months was compared between CDCs and placebo groups.ResultsIn total, 124 patients completed the 6-month follow-up (mean (SD) age 54.3 (10.8) and 108 (87.1%) men). Segmental Ecc improvement was significantly greater in patients receiving CDC (−0.5% (4.0)) compared with placebo (0.2% (3.7), p=0.05). The greatest benefit for improvement in segmental Ecc was observed in segments containing scar tissue (change in segmental Ecc of −0.7% (3.5) in patients receiving CDC vs 0.04% (3.7) in the placebo group, p=0.04).ConclusionsIn patients with post-MI LV dysfunction, CDC administration resulted in improved segmental myocardial function. Our findings highlight the importance of segmental myocardial function indices as an endpoint in future clinical trials of patients with post-MI.Trial registration numberNCT01458405.

Regulation of components of the brain and cardiac renin-angiotensin systems by 17β-estradiol after myocardial infarction in female rats

2006 ◽  
Vol 291 (1) ◽  
pp. R155-R162 ◽  
Author(s):  
Stephanie A. Dean ◽  
Junhui Tan ◽  
Roselyn White ◽  
Edward R. O’Brien ◽  
Frans H. H. Leenen
Keyword(s):  
Myocardial Infarction ◽  
Left Ventricular ◽  
Female Rats ◽  
Lv Function ◽  
Coronary Artery Ligation ◽  
Brain Nuclei ◽  
Renin Angiotensin ◽  
Lv Dysfunction ◽  
17Β Estradiol ◽  
The Brain

The present study tested the hypothesis that 17β-estradiol (E2) inhibits increases in angiotensin-converting enzyme (ACE) and ANG II type 1 receptor (AT1R) in the brain and heart after myocardial infarction (MI) and, thereby, inhibits development of left ventricular (LV) dysfunction after MI. Age-matched female Wistar rats were treated as follows: 1) no surgery (ovary intact), 2) ovariectomy + subcutaneous vehicle treatment (OVX + Veh), or 3) OVX + subcutaneous administration of a high dose of E2 (OVX + high-E2). After 2 wk, rats were randomly assigned to coronary artery ligation (MI) and sham operation groups and studied after 3 wk. E2 status did not affect LV function in sham rats. At 2–3 wk after MI, impairment of LV function was similar across MI groups, as measured by echocardiography and direct LV catheterization. LV ACE mRNA abundance and activity were increased severalfold in all MI groups compared with respective sham animals and to similar levels across MI groups. In most brain nuclei, ACE and AT1R densities increased after MI. Unexpectedly, compared with the respective sham groups the relative increase was clearest (20–40%) in OVX + high-E2 MI rats, somewhat less (10–15%) in ovary-intact MI rats, and least (<10–15%) in OVX + Veh MI rats. However, because in the sham group brain ACE and AT1R densities increased in the OVX + Veh rats and decreased in the OVX + high-E2 rats compared with the ovary-intact rats, actual ACE and AT1R densities in most brain nuclei were modestly higher (<20%) in OVX + Veh MI rats than in the other two MI groups. Thus E2 does not inhibit upregulation of ACE in the LV after MI and amplifies the percent increases in ACE and AT1R densities in brain nuclei after MI, despite E2-induced downregulation in sham rats. Consistent with these minor variations in the tissue renin-angiotensin system, during the initial post-MI phase, E2 appears not to enhance or hinder the development of LV dysfunction.

Abstract 14119: Contrasting Effects of Exercise Training After Acute Myocardial Infarction versus Aortic Stenosis Depend Critically on the Regulation of Endothelial Nitric Oxide Synthase

Circulation ◽  
2015 ◽  
Vol 132 (suppl_3) ◽  
Author(s):  
Yanti Octavia ◽  
Elza D van Deel ◽  
Monique de Waard ◽  
Martine de Boer ◽  
Dirk J Duncker
Keyword(s):  
Nitric Oxide ◽  
Myocardial Infarction ◽  
Exercise Training ◽  
Wheel Running ◽  
Left Ventricular ◽  
Lv Function ◽  
Enhanced Chemiluminescence ◽  
Lv Dysfunction ◽  
Enos Uncoupling ◽  
Endothelial Nitric Oxide

Introduction: The cardiovascular benefits of exercise training (EX) are widely appreciated. Previously we found that the cardiac effects of EX critically depend on the underlying cause of heart disease. Hypothesis: The underlying etiology determines how EX affects the endothelial nitric oxide (NO) synthase (eNOS)-mediated balance between NO and superoxide (O2-). Methods: Mice were subjected to sham surgery, myocardial infarction (MI) or transverse aortic constriction (TAC), and subsequently exposed to 8 weeks of voluntary wheel running or sedentary housing. Left ventricular (LV) function was assessed by echocardiography and hemodynamic measurements; fibrosis by Picro-sirius Red staining; peroxynitrite (ONOO-) and O2- production by luminol- and lucigenin-enhanced chemiluminescence respectively, with or without the NOS inhibitor L-NAME; eNOS uncoupling and eNOS S-glutathionylation by western blot and coimmunoprecipitation, respectively; cardiac NO by the Griess reaction. Results: EX ameliorated LV dysfunction and fibrosis in MI but not TAC (Table 1). Strikingly, O2- generation was blunted by EX in MI, but exacerbated by EX in TAC, which was largely NOS-dependent. Accordingly, eNOS uncoupling and eNOS S-glutathionylation were corrected by EX in MI but aggravated in TAC mice. In parallel, ONOO- levels was attenuated by EX in MI but aggravated by EX in TAC. Cardiac NO levels were reduced in MI and TAC and normalized by EX in MI. Conclusions: The contrasting effects of EX in MI vs TAC can be explained by the highly divergent effects of EX on eNOS regulation, resulting in blunted vs aggravated oxidative stress by EX in MI vs TAC.

Attenuation of left ventricular dysfunction by an ACE inhibitor after myocardial infarction in a kininogen-deficient rat model

2008 ◽  
Vol 389 (6) ◽  
Author(s):  
Matthias Koch ◽  
Klaus Bonaventura ◽  
Frank Spillmann ◽  
Andreas Dendorfer ◽  
Heinz-Peter Schultheiss ◽  
...  
Keyword(s):  
Myocardial Infarction ◽  
Ace Inhibitor ◽  
Diastolic Pressure ◽  
Ace Inhibition ◽  
Left Ventricular ◽  
Brown Norway ◽  
Lv Function ◽  
Maximal Rate ◽  
Lv Dysfunction

Abstract Bradykinin (BK) coronary outflow and left ventricular (LV) performance of kininogen-deficient Brown Norway Katholiek (BNK) rats and Brown Norway Hannover (BNH) controls were investigated. We analyzed whether the angiotensin-converting enzyme (ACE) inhibitor ramipril is able to attenuate LV dysfunction after induction of myocardial infarction (MI) in this animal model. Ex vivo, the basal BK content in the coronary outflow of buffer-perfused, isolated hearts was measured by specific radioimmunoassay. In vivo, left ventricular pressure (LVP), the maximal rate of LVP increase, LV end-diastolic pressure, the maximal rate of LVP decrease and heart rate were determined using a tip catheter 3 weeks after induction of MI. Compared to BNK rats, basal BK outflow was increased 30-fold in controls (p<0.01). In vivo, we found no significant differences between sham-ligated BNK and BNH rats in basal LV function. After MI, the impairment of LV function was significantly worse in BNK rats when compared to BNH rats. ACE inhibition significantly attenuated this LV dysfunction in both groups, when compared to untreated animals. Reduced basal BK level resulting from kininogen deficiency has no effect on basal LV function, but remains to be a risk factor for the ischemic heart. However, ACE inhibition is sufficient to improve LV function despite kininogen deficiency.

P5011Impact of guideline-recommended medical therapy at discharge on long-term mortality in patients with or without left ventricular dysfunction after primary PCI for STEMI

2019 ◽  
Vol 40 (Supplement_1) ◽  
Author(s):  
M Radomirovic ◽  
D Milasinovic ◽  
Z Mehmedbegovic ◽  
D Jelic ◽  
V Zobenica ◽  
...  
Keyword(s):  
Myocardial Infarction ◽  
Beta Blocker ◽  
Beta Blockers ◽  
Left Ventricular ◽  
Lv Function ◽  
Primary Pci ◽  
Lv Dysfunction ◽  
Concurrent Use ◽  
Tertiary Center ◽  
The Impact

Abstract Background Clinical practice guidelines provide class I recommendation for the use of angiotensin-converting enzyme inhibitors (ACE-I) and beta-blockers in patients with prior myocardial infarction and left ventricular (LV) dysfunction, whereas their use in patients without LV dysfunction is considered to be a class IIa recommendation. Purpose Our aim was to comparatively assess the impact of ACE-I and/or beta-blockers on 3-year mortality in patients with or without impaired left ventricular (LV) function undergoing primary percutaneous coronary intervention (PCI) for ST-segment elevation myocardial infarction (STEMI). Methods The analysis included 4425 patients admitted for primary PCI during 2009–2015 from a prospective, electronic registry of a high-volume tertiary center, who survived initial hospitalization, and for whom information on LV function and discharge medication were available. Patients were stratified according to LV systolic dysfunction, defined as LVEF <40%. Unadjusted and adjusted Cox regression models were created to investigate the impact of beta-blocker and/or ACE-I therapy on 3-year mortality. Results 22.9% (n=1013) had LV dysfunction, 23.0% (n=1017) received either an ACE-I or a beta-blocker and 72.2% received both medications at discharge (n=3197). The concurrent use of both ACE-I and beta-blockers was not different in LVEF≥40% vs. LVEF<40% (72.4% vs. 71.7%, p=0.43). The use of at least one of the guideline-recommended medications was associated with a significantly lower 3-year mortality in both patients with LVEF≥40% (18.7% if neither was used, 11.2% if either a beta-blocker or an ACE-I were used and 9.4% if both were used, p=0.001), and LVEF<40% (55.4% if neither was used, 32.5% if either a beta-blocker or an ACE-I were used and 22.9% if both were used, p<0.001) (Figure). After adjusting for significant mortality predictors including older age, diabetes, hypertension, renal failure, previous stroke, Killip class ≥2 and non-culprit chronic total occlusion (CTO), the concurrent use of both a beta-blocker and an ACE-I remained independently associated with lower 3-year mortality in both patients with LVEF<40% (HR 0.30, p<0.001) and LVEF≥40% (HR=0.41, p=0.001). The use of a single agent was independently associated with lower mortality in patients with LVEF<40% (HR 0.45, p=0.002), but not in patients with LVEF≥40% (HR 0.61, p=0.07). Conclusions Guideline-recommended use of both a beta-blocker and an ACE-I in post-MI patients was associated with a lower 3-year mortality regardless of the LV function, whereas using only one of the two agents was associated with improved prognosis only in patients with LV dysfunction, but not in patients without LV impairment.

Abstract 1509: Exercise Training Started Before Myocardial Infarction Improves Survival but Aggravates Left Ventricular Dysfunction

Circulation ◽  
2007 ◽  
Vol 116 (suppl_16) ◽  
Author(s):  
Monique C de Waard ◽  
Dirk J Duncker
Keyword(s):  
Myocardial Infarction ◽  
Exercise Training ◽  
Wheel Running ◽  
Left Ventricular ◽  
Lv Function ◽  
Cardiac Events ◽  
Cross Sectional ◽  
Voluntary Wheel Running ◽  
Lv Dysfunction ◽  
Voluntary Wheel

Introduction: Regular physical activity in patients with established coronary heart disease not only reduces the incidence of cardiac events, but also reduces the risk of all-cause mortality. Recently, we showed in mice that exercise training (EX) started immediately after myocardial infarction (MI) ameliorates left ventricular (LV) dysfunction. Here we tested the hypothesis that additional exercise training prior to an acute MI, i.e. a higher level of physical fitness at the time of MI, is associated with improved survival and attenuated LV dysfunction after MI. Methods and Results: MI was induced by permanent coronary ligation in 128 C57Bl/6 mice and subsequently followed by 8 weeks of voluntary wheel running (MI-EX) or sedentary housing (MI). In a third group, voluntary wheel running was started two weeks before induction of MI (EX-MI-EX). Sham operated mice served as controls. EX after MI had no effect on survival, infarct size, LV hypertrophy or dilation (Table ). However, EX improved LV function, reflected in enhanced LV fractional shortening (FS), rate of rise in LV pressure at 30 mmHg (LVdP/dt P30 ), and decreased pulmonary congestion and right ventricular weight (RVW). When EX was started prior to MI, post-MI survival nearly doubled and mice ran an average post-MI distance of ~7km/d compared to ~5km/d in MI-EX mice. Infarct cross-sectional area was larger, which was principally due to an increased infarct thickness (0.15±0.02mm EX-MI-EX vs 0.11±0.01mm MI; P =0.06). Surprisingly, however, LV hypertrophy and dysfunction were aggravated in the EX-MI-EX group compared to MI-EX. Conclusion: In line with our hypothesis, EX started prior to MI improved survival. However, contrary to our hypothesis, the improved survival was associated with a deterioration of LV dysfunction. The latter may have been the result of survival and hence inclusion of mice with the most severe LV dysfunction.

scholarly journals Association of C-Reactive Protein Velocity with Early Left Ventricular Dysfunction in Patients with First ST-Elevation Myocardial Infarction

2021 ◽  
Vol 10 (23) ◽  
pp. 5494
Author(s):  
Magdalena Holzknecht ◽  
Christina Tiller ◽  
Martin Reindl ◽  
Ivan Lechner ◽  
Priscilla Fink ◽  
...  
Keyword(s):  
Myocardial Infarction ◽  
Magnetic Resonance ◽  
Predictive Value ◽  
Left Ventricular ◽  
St Elevation Myocardial Infarction ◽  
Lv Function ◽  
C Reactive Protein ◽  
Reactive Protein ◽  
Lv Dysfunction ◽  
St Elevation

C-reactive protein velocity (CRPv) has been proposed as a very early and sensitive risk predictor in patients with ST-elevation myocardial infarction (STEMI). However, the association of CRPv with early left ventricular (LV) dysfunction after STEMI is unknown. The aim of this study was to investigate the relationship between CRPv and early LV dysfunction, either before or at hospital discharge, in patients with first STEMI. This analysis evaluated 432 STEMI patients that were included in the prospective MARINA-STEMI (Magnetic Resonance Imaging In Acute ST-elevation Myocardial Infarction. ClinicalTrials.gov Identifier: NCT04113356) cohort study. The difference of CRP 24 ± 8 h and CRP at hospital admission divided by the time (in h) that elapsed during the two examinations was defined as CRPv. Cardiac magnetic resonance (CMR) imaging was conducted at a median of 3 (IQR 2–4) days after primary percutaneous coronary intervention (PCI) for the determination of LV function and myocardial infarct characteristics. The association of CRPv with the CMR-derived LV ejection fraction (LVEF) was investigated. The median CRPv was 0.42 (IQR 0.21–0.76) mg/l/h and was correlated with LVEF (rS = −0.397, p < 0.001). In multivariable linear as well as binary logistic regression analysis (adjustment for biomarkers and clinical and angiographical parameters), CRPv was independently associated with LVEF (β: 0.161, p = 0.004) and LVEF ≤ 40% (OR: 1.71, 95% CI: 1.19–2.45; p = 0.004), respectively. The combined predictive value of peak cardiac troponin T (cTnT) and CRPv for LVEF ≤ 40% (AUC: 0.81, 95% CI 0.77–0.85, p < 0.001) was higher than it was for peak cTnT alone (AUC difference: 0.04, p = 0.009). CRPv was independently associated with early LV dysfunction, as measured by the CMR-determined LVEF, revealing an additive predictive value over cTnT after acute STEMI treated with primary PCI.

Changes in left ventricular function and remodeling after myocardial infarction in hypothyroid rats

2010 ◽  
Vol 298 (1) ◽  
pp. H259-H262 ◽  
Author(s):  
Yue-Feng Chen ◽  
Rebecca A. Redetzke ◽  
Suleman Said ◽  
April J. Beyer ◽  
A. Martin Gerdes
Keyword(s):  
Myocardial Infarction ◽  
Left Ventricular ◽  
Experimental Myocardial Infarction ◽  
Lv Function ◽  
Sprague Dawley ◽  
Lv Dysfunction ◽  
Long Term Effect ◽  
Sprague Dawley Rats ◽  
Lv Remodeling

It has been shown that hypothyroidism may lead to delayed wound healing after experimental myocardial infarction (MI) in rats and increased infarct size in dogs. However, the long-term effect of hypothyroidism on left ventricular (LV) remodeling after MI has not been determined. Adult female Sprague-Dawley rats with and without surgical thyroidectomy (TX) were used in the study. Four weeks after TX, MI or sham MI was performed on TX and non-TX rats. Rats from all groups were examined 4 wk later. Four weeks after TX, hypothyroid-induced LV dysfunction was confirmed by echocardiography. In terminal experiments 4 wk after MI, TX sham-MI rats showed smaller hearts and impaired LV function compared with non-TX sham-MI controls. TX + MI rats showed smaller hearts with bigger infarct areas, higher LV end-diastolic pressures, and greater impairment of relaxation (−dP/d t) compared with non-TX MI rats. Relative changes after MI between TX and non-TX rats for most other hemodynamic and echocardiographic indexes were similar. These results suggest that preexisting hypothyroidism exaggerates post-MI remodeling and worsens LV function, particularly diastolic function.

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