Relationship between Neovascularization and Aortic Wall Enhancement in Type A Aortic Dissection.

Background:  Aortic wall enhancement (AWE), evaluated with computed tomography angiography in Type B aortic dissection, is associated with aortic remodeling. This study aimed to evaluate the relationship between AWE and pathological findings of the aortic wall using an aortic wall sample from a Type A aortic dissection (TAD).

Methods:  We examined patients with TAD treated between January 2012 and February 2023.

Results:  Twelve cases were examined pathologically: five cases in the hyperacute phase, three in the acute phase, and four in the subacute phase. AWE thickness significantly differed as time progressed (0 vs. 1.7 vs. 2.8 mm, p < 0.001). A significant increase in granulation was observed in the acute and subacute phases (0 vs. 761 vs. 423 µm, p < 0.001). Furthermore, a fibrous complex of internal adventitia (FCIA) developed on the medial side of the adventitia over time since its onset and was found to be thickened (175 vs. 415 vs. 1,078 µm, p < 0.001). The thickness of the granulation tissue and FCIA, where there was abundant neovascularization, was consistent with the thickness of the AWE.

Conclusion:  AWE was observed in TAD and increased as time progressed. FCIA and granulation tissue developed, and AWE reflected neovascularization at the adventitia.