Histological regional analysis of the aortic root and thoracic ascending aorta: a complete analysis of aneurysms from root to arch

Timothy Luke Surman, John Matthew Abrahams, Jim Manavis, John Finnie, Dermot O’Rourke, Karen Jane Reynolds, James Edwards, Michael George Worthington, John Beltrame

Research output: Contribution to journalArticlepeer-review

Abstract

Background: Although aortic root and ascending aortic aneurysms are treated the same, they differ in embryological development and pathological processes. This study examines the microscopic structural differences between aortic root and ascending aortic aneurysms, correlating these features to the macroscopic pathophysiological processes. Methods: We obtained surgical samples from ascending aortic aneurysms (n = 11), aortic root aneurysms (n = 3), and non-aneurysmal patients (n = 7), Aortic collagen and elastin content were examined via histological analysis, and immunohistochemistry techniques used to determine collagen I, III, and IV subtypes. Analysis was via observational features, and colour deconvolution quantification techniques. Results: Elastin fiber disruption and fragmentation was the most extensive in the proximal aneurysmal regions. Medial fibrosis and collagen density increased in proximal aneurysmal regions and aortic root aneurysms (p < 0.005). Collagen I was seen in highest quantity in aortic root aneurysms. Collagen I content was greatest in the sinus tissue regions compared to the valvular and ostial regions (p < 0.005) Collagen III and IV quantification did not vary greatly. The most susceptible regions to ultrastructural changes in disease are the proximal ascending aorta and aortic root. Conclusions: The aortic root differs histologically from the ascending aorta confirming its unique composition in aneurysm pathology. These findings should prompt further evaluation on the influence of this altered structure on function which could potentially guide clinical management.

Original languageEnglish
Article number255
Number of pages10
JournalJournal of Cardiothoracic Surgery
Volume16
Issue number1
DOIs
Publication statusPublished - 8 Sep 2021

Keywords

  • Aneurysms
  • Aortic root
  • Ascending aorta
  • Histology
  • Immunohistochemistry

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