Aortic Thickness: A Forgotten Paradigm in Risk Stratification of Aortic Disease

Abstract

Background This study aimed at risk-stratifying aortic dilatation using aortic wall thickness (AWT) and comparing methods of AWT assessment. Methods Demographic, epidemiological, and perioperative data on 72 consecutive aortic surgeries (age = 62 years[standard deviation (SD) = 12] years) performed by a single surgeon were collected from hospital database. Aortic thickness was measured on computed tomography scans, as well as intraoperatively in four quadrants, at the level of aortic sinuses, as well as midascending aorta, using calipers. Aortic wall stress was calculated using standard mathematical formulae. Results The ascending aorta was 48.2 (SD = 8) mm and the mean thickness at ascending aorta level was 1.9 (SD = 0.3) mm. There was congruence between imaging and intraoperative measurements of thickness, as well as between the radiologist and surgeon. Preoperatively, 16 patients had multiple imaging studies showing an average rate of growth of 1.2 mm per year without significant difference in thickness. The wider the aorta, the thinner was the lateral or convex wall. Aortic stenosis (p = 0.01), lateral to medial wall thickness ratio (p = 0.04), and history of hypertension (p = 0.00), all had protective effect on aortic root stress. The ascending aortic stress was directly affected by age (p = 0.03) and inversely related to lateral to medial wall thickness ratio (p = 0.03). Conclusion Aortic thickness can be measured preoperatively and easily confirmed intraoperatively. Risk stratification based on both aortic thickness and diameter (stress calculations) would better predict acute aortic events in dilated aortas and define aortic resection criteria more objectively.

Evidence in Clinical Studies for the Role of Wall Thickness in Ascending Thoracic Aortic Aneurysms: A Scoping Review

“…A key finding is that no noticeable variation in wall thickness with respect to aortic diameters was observed ( Figure 3 ). This finding is opposed to a perceived general characteristic of aortic aneurysms, which is outward hypotrophic remodelling [ 20 , 30 ]. The findings from histopathological studies also describe hyperplasia of VSMCs leading to either thickening or maintenance of thickness instead of thinning of the aortic wall under aneurysmatic conditions [ 29 ].…”

“…After a review of the full articles, eight articles were excluded from analysis because wall thickness or overall wall thickness was not presented ( n = 6), it was unclear which layer of tissue was measured ( n = 1) or data on the ascending aorta were not presented ( n = 1). This resulted in 15 studies, with a total of 1556 ATAA tissue samples, which were included in this review [ 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 ].…”

The effect of terminal impedance on aortic morphology and hemodynamics: an in vitro phantom study using flow field visualization

“…Moreover, because of the positive Poisson’s ratio of silicone and the aortic wall, elongation and dilation of the aorta leads to qualitative thinning of the aortic walls, especially in the ascending aorta. This situation means that the aortic wall is under greater stress, but this stress can be decreased by reducing the aortic diameter and thickening the aortic wall ( Hardikar et al, 2020 ). At the level of bioregulation, experiments in hypertensive rats ( Intengan and Schiffrin, 2001 ) have demonstrated enhanced arterial remodeling.…”

Apoptotic Cell Death in Bicuspid-Aortic-Valve-Associated Aortopathy

“…Furthermore, the integration of α-smooth muscle actin into stress fibers significantly enhances the contractile activity of fibroblastic cells [ 48 ]. The significant increase in α-smooth muscle actin expression on the concave site of the aorta of patients with BAV could thus be associated with a strengthening of the extracellular matrix and explain why aneurysms mostly develop on the convex site [ 49 ].…”