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Medial degeneration does not involve uniformly the whole ascending aorta: morphological, biochemical and clinical
L Agozzino1, F Ferraraccio, S Esposito
1Department of Public Medicine, Section of Pathology, Second University of Naples, Naples, Italy.
Insights
Medial degeneration (MD) lesions are more severe in the postero-lateral wall of the dilated intrapericardial aorta compared to the anterior wall. This difference in medial degeneration severity is likely due to uneven hemodynamic stress distribution.
Area of Science:
- Cardiovascular Pathology
- Aortic Disease Research
- Biomedical Engineering
Background:
- Medial degeneration (MD) is a pathological process affecting the aorta.
- Dilatation of the intrapericardial aorta is associated with aortic valve disease.
- Understanding regional variations in MD severity is crucial for managing aortic aneurysms.
Purpose of the Study:
- To investigate regional differences in the severity of medial degeneration (MD) lesions within the dilated intrapericardial aorta.
- To determine if MD severity varies circumferentially along the aorta.
- To explore potential correlations between aortic dilatation and MD severity.
Main Methods:
- Harvested aortic wall specimens from two locations: non-coronary (NC) sinus (postero-lateral wall) and right coronary sinus (anterior wall) in 22 patients.
- Pathology, morphometry, and ultrastructural examination of specimens to assess MD severity.
- Paired t-test and correlation analyses to compare MD severity and relate it to aortic dilatation.
Main Results:
- Medial degeneration (MD) was present in all cases.
- Significantly higher mean MD severity was observed in the NC (postero-lateral) specimens compared to the coronary (anterior) specimens (P<0.001).
- Morphometric analysis revealed reduced smooth muscle cells and altered elastic fibers in the NC specimens, with a significant correlation between aortic ratio and MD severity in this region.
Conclusions:
- Medial degeneration (MD) lesions are more severe in the postero-lateral wall (NC area) of the dilated intrapericardial aorta.
- This regional disparity in MD severity is likely attributed to asymmetric hemodynamic stress.
- Findings highlight the importance of considering circumferential variations in aortic pathology.
Objective:
To investigate whether and how the severity of medial degeneration (MD) lesions varies along the circumference of the dilated intrapericardial aorta.
Methods:
Two groups of aortic wall specimens, respectively harvested 1cm distal to the non-coronary (NC) sinus (right postero-lateral wall) and to the right coronary sinus (anterior wall) in 22 patients undergoing surgery for dilatation of the intrapericardial aorta associated with aortic valve disease, were separately sent for pathology, morphometry and ultrastructural examination. MD lesions found at histology were classified into three degrees of severity. MD mean degree and morphometric findings in postero-lateral ('NC') and anterior ('coronary') specimens were compared by paired t-test. Correlation between degree of aortic dilatation at echocardiography and severity of MD was assessed separately for each of the two groups of specimens. After the preliminary results of the morphological study, we decided to send the specimens for biochemical investigation of protein electrophoretic patterns. This was performed in the last seven patients of this series.
Results:
At histology, MD was found in all cases. A higher mean MD degree was found in the NC group (2.59+/-0.50 versus 1.59+/-0.67 in the coronary group; P<0.001). At morphometry, normal smooth muscle cells in the NC specimens were significantly reduced (P=0.012) and the length (P=0.011) and number (P=0.015) of elastic fibres reduced and increased, respectively. Correlation between aortic ratio and MD degree was significant in the NC specimens (P<0.001), not in the coronary ones (P=0.227). Quantitative differences between coronary and NC proteins from the same patient and between coronary proteins from different patients were found at electrophoresis. However, at this stage of the study, the sample was too small to allow for the identification of proteins involved in those differences.
Conclusions:
MD lesions in dilated intrapericardial aorta are more severe in the right postero-lateral wall area, likely due to haemodynamic stress asymmetry.