Related Experiment Videos
Quantitative ultrastructure of the myocardium in chronic aortic valve disease
Insights
In advanced mixed aortic valve disease, a reduced intracellular contractile material and increased sarcoplasmic volume lead to impaired left ventricular contractility. This cellular change explains reduced ejection fraction in these patients.
Area of Science:
- Cardiovascular Pathology
- Cardiac Hypertrophy
- Aortic Valve Disease
Background:
- Chronic aortic valve disease leads to significant left ventricular remodeling.
- Understanding cellular changes in hypertrophy is crucial for managing heart failure.
Purpose of the Study:
- To investigate the morphometric and hemodynamic differences in the left ventricle among patients with distinct chronic aortic valve diseases.
- To identify cellular mechanisms underlying impaired contractility in mixed aortic valve disease.
Main Methods:
- Light and electron microscopic morphometry of left ventricular free wall tissue samples.
- Hemodynamic assessment, including ejection fraction and wall stress, before open-heart surgery.
- Comparison of intracellular contractile material, sarcoplasmic volume, mitochondrial volume, and interstitial fibrosis across patient groups.
Main Results:
- Patients with mixed aortic valve disease exhibited higher left ventricular mass and lower ejection fraction compared to aortic stenosis.
- Intracellular contractile material was reduced, and sarcoplasmic volume was increased in mixed aortic valve disease versus aortic stenosis.
- No significant differences in mitochondrial volume or interstitial fibrosis were observed between groups.
Conclusions:
- An intracellular deficiency of myofibrils contributes to impaired contractility in advanced hypertrophy associated with mixed aortic valve disease.
- This cellular deficit is a key factor in the reduced ejection fraction seen in these patients.
Abstract:
Light and electron microscopic morphometry was carried out in tissue samples which were obtained from the left ventricular free wall in 29 patients with chronic aortic valve disease during open-heart surgery. 6 patients had aortic stenosis, 9 had aortic insufficiency and 14 had a mixed aortic valve lesion. Hemodynamics were studied before operation. Patients with mixed aortic valve disease had a higher left ventricular mass, a lower ejection fraction and mean circumferential fiber shortening rate than patients with aortic stenosis. Peak systolic wall stress was comparable between groups. The intracellular content of contractile material was lower and the sarcoplasmic volume was higher in mixed aortic valve disease than in aortic stenosis. Mitochondrial volume and interstitial fibrosis were not different between groups. Patients with aortic insufficiency showed no significant difference of parameters as compared to both other groups. We conclude that an intracellular deficiency of myofibrils causes lack of contractility in advanced hypertrophy due to mixed aortic valve disease.