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Ultrastructural features of diseased human atrial muscle cells
Abstract:
Left atrial myocardial tissues, excised at the time of surgery from 30 Japanese patients, were studied using light and electron microscopy and the freeze-fracture technique. All had mitral valvular disease, and, in 22 (74%) patients, atrial fibrillation also was present. In all patients, most of the left atrial cardiocytes were hypertrophied and surrounded by various amounts of fibrous tissue. Degenerative alterations included large masses of lipofuscin granules and lamellar bodies, disorganized myofibrils, widened Z-line material, selective loss of thick filaments, and prominent tubules of sarcoplasmic reticulum. A high incidence of tubular aggregates was observed in 70% of the cases. Such alterations were seen more often in the mitral regurgitation group as compared to the mitral stenosis group. Atrial cardiocytes were found to be more susceptible to disease processes, such as rheumatic fever and subsequent pressure and/or volume overloading, than ventricular cardiocytes. Human atrial cardiocytes may be utilized in future cytopathological studies to study the effect of processes leading to cardiocyte hypertrophy and degeneration.
Insights
Left atrial cardiocytes in patients with mitral valve disease show significant hypertrophy and degeneration. These findings highlight atrial cardiocyte susceptibility to cardiac disease processes.
Area of Science:
- Cardiology
- Cell Biology
- Pathology
Background:
- Left atrial myocardial tissues are affected by mitral valvular disease.
- Atrial fibrillation is a common comorbidity in patients with mitral valvular disease.
- Understanding cellular changes in the atria is crucial for managing heart conditions.
Purpose of the Study:
- To investigate the ultrastructural changes in left atrial cardiocytes from patients with mitral valvular disease.
- To compare cellular alterations between mitral regurgitation and mitral stenosis.
- To assess the susceptibility of atrial cardiocytes to disease-induced hypertrophy and degeneration.
Main Methods:
- Light and electron microscopy were used to examine myocardial tissues.
- Freeze-fracture technique was applied to study cellular structures.
- Tissues were obtained from 30 Japanese patients undergoing surgery for mitral valvular disease.
Main Results:
- All patients exhibited hypertrophied left atrial cardiocytes with surrounding fibrosis.
- Common degenerative alterations included lipofuscin, lamellar bodies, disorganized myofibrils, and sarcoplasmic reticulum changes.
- Tubular aggregates were observed in 70% of cases, more frequently in mitral regurgitation.
Conclusions:
- Left atrial cardiocytes are highly susceptible to hypertrophy and degeneration in mitral valvular disease.
- Specific ultrastructural changes indicate cellular stress and damage.
- Atrial cardiocytes serve as a valuable model for studying cardiac hypertrophy and degeneration.