Background: Aortic aneurysm is a common medical and surgical emergency in the general population. The two most common important causes of aortic aneurysms are atherosclerosis and cystic medial degeneration of the arterial media. This study focuses on the different histologic abnormalities found in aortic aneurysm, which include cystic medial degeneration, laminar medial necrosis, intramedial dissection, aortitis and normal media. This study reviews the clinical and histopathologic features of excised ascending aortic aneurysms from the Philippine Heart Center.
Methods: This is a retrospective cross-sectional study involving archival cases from institutional and surgical pathology files from the Biological and Clinical Laboratory Division from patients who underwent aortic surgery between January 01, 2000 and August 31, 2007. Histoloqic slides were reviewed for the presence of arterial segment and stained with special stain (Elastic stain) to evaluate histologic abnormalities. A criterion is applied based on the study done by Homme et al.14 Demographic profiles of patients, clinical diagnosis and concomitant surgery performed were also analyzed.
Results: A total of 345 patients underwent aortic aneurysm surgery at the Philippine Heart Center, 238 of which had aortic wall segment and 107 cases showed thrombus or plaques only, hence were excluded. Another 80 were excluded due to incomplete or missing charts and/or missing paraffin blocks while 5 cases were found to be arterial segments rather than from the aorta. A total of 153 patients were included where 105 were males and 48 were females with their ages ranging from 19-82 years old and a mean age of 55.7 years. The predominant initial surgical indication is aneurysm or dissection (146/153), while 4 patients were initially scheduled for valvular replacement and another 3 patients for CABG. The common risk factors include hypertension, smoking, CAD, Diabetes Mellitus and Marfan's syndrome. Concomitant surgeries performed were AVR, CABG and MVR. Atherosclerosis is the most common histologic finding seen in aortic walls. Among the primary medial processes, cystic medial degeneration is the most common followed by aortic dissection. A small number of cases had aortitis but majority of the patient had a combination of the different histologic features. Increasing age, hypertension, CAD and smoking history are inversely related to severity of CMD but, Marfan's syndrome is significant risk factor for CMD. No risk factors were found to be statistically significant with the development of aortic dissection.
Conclusion: Histopathology of aortic aneurysmal wall has a wide range of findings. The most common histologic change in our institution remains to be atherosclerosis regardless of age, gender and risk factors. Among the primary medial processes involved, majority is due to cystic medial degeneration followed by aortic dissection. Severity of cystic medial degeneration is affected by younger age and male gender. Marfan's syndrome showed strong positive association with the severity of CMD. Presence of a variable degree of adventitial inflammatory cells in aneurysmal wall was consistently seen in our study regardless of the histologic findings seen. This may connote an attempt of the body's mechanism to eradicate or at least repair whatever is damaged in the aortic wall.