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Chronic hibernating myocardium: interstitial changes
J Ausma1, J Cleutjens, F Thoné
1Department of Molecular Cell Biology and Genetics, Cardiovascular Research Institute Maastricht, University of Limburg, The Netherlands.
Insights
Chronic myocardial hibernation involves cardiomyocyte de-differentiation and increased interstitial tissue, including collagen and fibronectin. This structural remodeling hinders immediate functional recovery after blood flow restoration in left ventricular dysfunction.
Area of Science:
- Cardiovascular Biology
- Cardiac Pathophysiology
- Myocardial Remodeling
Background:
- Chronic hibernation in left ventricular dysfunction involves viable but dysfunctional myocardium.
- Structural changes include contractile element depletion and cardiomyocyte de-differentiation.
- These changes are associated with significant alterations in the interstitial space.
Purpose of the Study:
- To describe qualitative and quantitative changes in the cellular and non-cellular interstitial compartments.
- To investigate the role of interstitial remodeling in impaired cardiac function recovery.
Main Methods:
- Histological analysis of myocardial segments from patients with chronic left ventricular dysfunction.
- Qualitative and quantitative assessment of interstitial space components.
- Immunohistochemical detection of vimentin-positive cells.
Main Results:
- Cardiomyocytes show de-differentiation, not degeneration.
- Increased interstitial space is filled with type I collagen, type III collagen, and fibronectin.
- An increased number of vimentin-positive cells (endothelial cells, fibroblasts) is observed.
Conclusions:
- Interstitial fibrosis and cellular changes are key features of chronic myocardial hibernation.
- Increased interstitial tissue contributes significantly to the delayed recovery of contractile function post-reperfusion.
- Understanding these structural changes is crucial for managing left ventricular dysfunction.
Abstract:
Chronic left ventricular dysfunctional but viable myocardium of patients with chronic hibernation is characterized by structural changes, which consist of depletion of contractile elements, accumulation of glycogen, nuclear chromatin dispersion, depletion of sarcoplasmic reticulum and mitochondrial shape changes. These alterations are not reminiscent of degeneration but are interpreted as de-differentiation of the cardiomyocytes. The above mentioned changes are accompanied by a marked increase in the interstitial space. The present study describes qualitative and quantitative changes in the cellular and non-cellular compartments of the interstitial space. In chronic hibernating myocardial segments the increased extracellular matrix is filled with large amounts of type I collagen, type III collagen and fibronectin. An increase in the number of vimentin-positive cells (endothelial cells and fibroblasts) compared with normal myocardium is seen throughout the extracellular matrix. The increase in interstitial tissue is considered as one of the main determinants responsible for the lack of immediate recovery of contractile function after restoration of the blood flow to the affected myocardial segments of patients with chronic left ventricular dysfunction.