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Myocardial structure and left ventricular function in hypertrophic and dilative cardiomyopathy and aortic valve
1Medizinische Poliklinik der Universität Erlangen, F.R.G.
Insights
Left ventricular function deteriorates with increased myocyte cell and nuclear size in cardiomyopathy and aortic valve disease. Myofibril volume fraction decreases as left ventricular function worsens.
Area of Science:
- Cardiology
- Pathology
- Cell Biology
Background:
- Left ventricular dysfunction is a hallmark of various heart conditions.
- Understanding the relationship between myocardial structure and function is crucial for diagnosis and treatment.
- Previous studies have suggested links between cellular changes and impaired heart function.
Purpose of the Study:
- To investigate the correlations between myocardial structural changes and left ventricular function in patients with different cardiomyopathies and aortic valve disease.
- To determine if specific ultrastructural findings are associated with the severity of ventricular dysfunction.
- To analyze the volume fractions of mitochondria and myofibrils in relation to cardiac disease.
Main Methods:
- Analysis of left ventricular biopsies from 126 patients with varying degrees of cardiomyopathy and 18 patients with aortic valve disease.
- Quantification of myocyte cell diameter, nuclear size, mitochondrial volume, and myofibril volume fraction.
- Statistical correlation analysis between structural parameters and left ventricular ejection fraction (EF).
Main Results:
- Deterioration of ventricular function correlated with increased myocyte cell diameter (r=0.47-0.6) and nuclear size (r=0.74-0.9) in dilated cardiomyopathies and aortic valve disease.
- Mitochondrial volume remained constant (23%) across different conditions.
- Myofibril volume fraction decreased significantly with worsening left ventricular function in dilated cardiomyopathies and aortic valve disease, while remaining relatively preserved in hypertrophic cardiomyopathy.
Conclusions:
- The degree of myocardial hypertrophy and specific ultrastructural alterations are inversely correlated with left ventricular function.
- Cellular and nuclear enlargement are associated with impaired ventricular performance.
- Myofibril loss is a key feature of functional decline in certain cardiac conditions.
Abstract:
Left ventricular biopsies from 126 patients with advanced (EF less than 50%, n = 45) and mild (EF 50-60%, n = 21) and latent cardiomyopathy (EF greater than 60%, n = 60) and 18 additional patients with aortic valve disease and 22 cases with hypertrophic cardiomyopathy were analyzed to define possible correlations between myocardial structure and function. Deterioration of ventricular function was combined with increasing muscle cell diameters (r = 0.47) and increasing nuclear size of the myocytes (r = 0.74) in latent and dilative cardiomyopathies and in patients with aortic valve disease (cell diameter, r = 0.6; nuclear size, r = 0.9). Patients with HCM showed a wide range of cell diameter and nuclear size. 24% of the latter patients had no bioptic evidence of myocardial hypertrophy. The mitochondrial volume of the myocytes was 23% in the normal and hypertrophied myocardium independent of the kind of disease and ventricular function. The volume fraction of the myofibrils continuously decreased with worsening of the left ventricular function in patients with latent and dilative cardiomyopathy (from 45 +/- 6.9 to 37.6 +/- 6.3%) and aortic valve disease (from 46.2 +/- 3.4 to 27.9 +/- 9.3%). Patients with hypertrophic cardiomyopathy presented with normal or slightly decreased values of myofibrils consistent with normal ventricular function (42.5 +/- 5.0). The data demonstrate that the degree of myocardial hypertrophy and certain ultrastructural findings are inversely correlated with left ventricular function.