Evaluation of the intraoperative specimens of the thoracic and abdominal aorta

Little is known about the histological patterns of acute and chronic aortic pathology with regard to medial degeneration, atherosclerosis and aortitis as well as their distribution in different age groups. The aim of the study was to evaluate histopathological findings of intraoperatively gained aortic specimens with regard to the incidence of medial degeneration, atherosclerosis and aortitis.

Intraoperatively gained aortic specimens were evaluated in 151 patients including 83 (55%) aortic aneurysms (65 thoracic, 18 abdominal) and 68 (45%) acute type A aortic dissections. Histological stainings used were hematoxylin and eosin, Van Gieson as well as alcian blue. Patients were stratified according to above and below 65 years of age. High grade medial degeneration represented pooling of mucoid material in the whole aortic wall. High grade atherosclerosis represented severe intimal fibrosis, massive accumulation of macrophages and foam cells or massive calcification of the aortic wall.

Medial degeneration was diagnosed in 106 (70%) patients including 55 (52%) aortic aneurysms and 51 (48%) acute type A aortic dissections. High grade medial degeneration was found in 50% of patients with thoracic aortic aneurysms < 65 years of age vs. 44% in patients ≥ 65 years of age (p = 0.64) and in 36% of patients with thoracic aortic dissections < 65 years of age vs. 14% in patients ≥ 65 years of age (p = 0.07). Atherosclerosis was diagnosed in 71 (47%) patients including 46 (65%) aortic aneurysms and 25 (35%) aortic dissections. High grade atherosclerosis was found in 23% of patients with thoracic aneurysms < 65 years of age vs. 36% in patients ≥ 65 years of age (p = 0.24) and in 13% of patients with aortic dissections < 65 years of age vs. 52% in patients ≥ 65 years of age (p < 0.001). Aortitis was rare (n = 2).

Medial degeneration was the most frequent diagnosis in this series of aortic specimens. Medial degeneration was equally common in patients above and below 65 years of age. However in cases with acute type A aortic dissections, high grade atherosclerosis was the leading histopathological diagnosis in patients older than 65 years. Acute type A aortic dissections seem to have different underlying pathologies in different age groups.