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The hypertrophied myocardium and coronary disease. Structural changes in patients submitted to aortocoronary bypass
R Ferreira1, J Milei, P Forcada
1Department of Cardiovascular Surgery, ECAVI, Policlinico Bancario, Buenos Aires, Argentina.
Insights
Hypertrophied hearts show increased fibrous tissue and myocyte size, leading to greater susceptibility to ischemia/reperfusion injury. Damaged mitochondria also increase post-reperfusion in these hearts.
Area of Science:
- Cardiovascular Biology
- Cardiac Pathology
- Myocardial Revascularization
Background:
- Coronary artery disease (CAD) affects millions worldwide.
- Myocardial revascularization is a common treatment for CAD.
- Ventricular hypertrophy is a significant risk factor for cardiac events.
Purpose of the Study:
- To investigate the impact of ventricular hypertrophy on myocardial tissue characteristics.
- To assess the susceptibility of hypertrophied ventricles to ischemia/reperfusion injury.
- To compare ultrastructural changes in normal versus hypertrophied ventricles post-revascularization.
Main Methods:
- Seventeen patients with coronary disease undergoing myocardial revascularization were studied.
- Patients were divided into groups with hypertrophied ventricles (n=10) and normal ventricular mass (n=7).
- Myocardial biopsies were analyzed pre-ischemia and post-reperfusion for fibrous tissue, myocyte diameter, mitochondrial morphology, and ultrastructural changes.
Main Results:
- Hypertrophied ventricles exhibited significantly higher fibrous tissue volume fraction (1.9% vs 0.9%) and myocyte diameter (23µm vs 18µm) compared to normal ventricles.
- Pre-ischemia mitochondrial volumetric density was lower in hypertrophied ventricles (23 vs 35).
- Reperfusion led to a significant increase in severe mitochondrial damage (Grades 3 & 4) in hypertrophied hearts, indicating heightened sensitivity to ischemia/reperfusion.
Conclusions:
- Increased collagen deposition and myocyte hypertrophy in certain hearts correlate with greater vulnerability to ischemia/reperfusion injury.
- Mitochondrial damage is exacerbated in hypertrophied ventricles following revascularization.
- These findings suggest that ventricular hypertrophy alters myocardial structure and function, increasing susceptibility to reperfusion-related damage.
Abstract:
Seventeen patients with coronary disease submitted to myocardial revascularization were studied. Ten patients had a hypertrophied ventricle, and 7 had normal ventricular mass. Myocardial biopsies were obtained before ischemia and at the time of reperfusion and were assessed for: volume fraction of fibrous tissue, myocyte diameter, morphometric mitochondrial studies and ultrastructural changes. The volume fraction of fibrous tissue in patients with hypertrophied ventricle was 1.9 +/- 0.04, and in patients with normal ventricular mass was 0.9 +/- 0.01 (p less than 0.05). The diameter of the myocyte was 23 +/- 0.3 microns and 18 +/- 1.2 microns for patients with hypertrophied and normal ventricular mass, respectively (p less than 0.01). The value of volumetric density for pre-ischemia samples in patients with a hypertrophied ventricle was 23 +/- 2.2 and in patients with normal ventricular mass was 35 +/- 2.7 (p less than 0.02). Grades 3 and 4 of damaged mitochondria were significantly increased in reperfusion samples from patients with a hypertrophied ventricle compared to pre-ischemia samples. Collagen growth was increased in hypertrophied hearts which were also more sensitive to the ischemia/reperfusion mechanism.