Journal of cardiovascular development and disease, Volume 8, Issue 2, 27 4 2021 A Systematic Histopathologic Evaluation of Type-A Aortic Dissections Implies a Uniform Multiple-Hit Causation. Grewal N, Velders BJJ, Gittenberger-de Groot AC, Poelmann R, Klautz RJM, Van Brakel TJ, Lindeman JHN

(1) Background

The pathophysiologic basis of an acute type A aortic dissection (TAAD) is largely unknown. In an effort to evaluate vessel wall defects, we systematically studied aortic specimens in TAAD patients. (2) Methods

Ascending aortic wall specimens (n = 58, mean age 63 years) with TAAD were collected. Autopsy tissues (n = 17, mean age 63 years) served as controls. All sections were studied histopathologically. (3) Results

Pathomorphology in TAAD showed predominantly moderate elastic fiber fragmentation/loss, elastic fiber thinning, elastic fiber degeneration, mucoid extracellular matrix accumulation, smooth muscle cell nuclei loss, and overall medial degeneration. The control group showed significantly fewer signs of those histopathological features (none-mild, p = 0.00). It was concluded that the dissection plane consistently coincides with the vasa vasorum network, and that TAAD associates with a significantly thinner intimal layer p = 0.005). (4) Conclusions

On the basis of the systematic evaluation and the consistent presence of diffuse, pre-existing medial defects, we hypothesize that TAAD relates to a developmental defect of the ascending aorta and is caused by a triple-hit mechanism that involves (I) an intimal tear; and (II) a diseased media, which allows (III) propagation of the tear towards the plane of the vasa vasorum where the dissection further progresses.

Keywords: Aorta, Cardiovascular disease, Acute Aortic Syndrome

J Cardiovasc Dev Dis. 2021 1;8(2)