We emergently performed ascending aortic and total arch replacement in a 64-year-old woman with Stanford A type acute aortic dissection (AAD) that reached the abdominal aortic bifurcation. Concomitantly, coronary artery bypass grafting to the right coronary artery was also required. After AAD surgery, the patient recovered normally and did not experience any specific symptoms.
Follow-up computed tomography (CT) images obtained 23 days after AAD surgery revealed a VAA with enhancement, which appeared to lie in front of superior mesenteric artery (SMA) and behind the pancreas body (). The aneurysm was approximately 20 mm in diameter, and the artery that seemed to be responsible was the PIPDA (
). This aneurysm could not be enhanced on CT images obtained before AAD surgery (). Additionally, follow-up CT images showed that dissecting lesions remained at the abdominal aorta, especially around the orifices of the celiac artery, SMA and renal arteries. Percutaneous interventional approach with coil embolization could be one of available treatments to be performed, but endovascular treatment for this patient was considered to be so difficult technically and carry the risk of aortic rupture. Therefore, the surgical resection of the aneurysm was determined to be performed to prevent the aneurysm rupture.
Fig. 1 (A, B) Two-dimensional (A) and three-dimensional (B) computed tomography (CT) images obtained after acute aortic dissection (AAD) surgery. The enhanced aneurysm appeared to lie in front of superior mesenteric artery and behind the pancreas body. This (more ...)
The patient had undergone a total gastrectomy, including splenectomy and cholecystectomy, due to gastric carcinoma 17 years prior to AAD surgery. No recurrence of the gastric carcinoma was found. The patient had no history of abdominal trauma or pancreatitis. Similarly, she did not have any characteristics associated with vasculitis, such as Behçet’s disease, and hereditary collagen diseases, such as Ehlers-Danlos syndrome.2)
In the clinical course after AAD surgery, complete blood cell counts and C-reactive protein levels were within accepted limits for patients recovering from AAD surgery, and pancreatic amylase was within the normal range. There were no bacteria isolated from the patient’s blood culture. Etiologies resulting in VAA for this patient were unclarified.
Forty-four days after AAD surgery, this patient underwent a second operation. The aneurysm was accessed via an upper median and left subcostal incision. Intraperitoneal adhesion between each organ was severe due to the previous open surgery. Macroscopically, the aneurysm appeared to lie behind the pancreas body, and two vessels, which were probably PIPDA, appeared to be connected to this aneurysm, as seen on the CT images. The whole aneurysm and its feeding arteries could not be exposed due to severe adhesion to the surrounding tissues nearby pancreas, and it was impossible to resect only the aneurysm or to ligate the feeding arteries. A distal pancreatectomy was required concomitantly to complete the resection of the aneurysm. Observation of the resected aneurysm showed that its surface was smooth, and neither inflammation, infection, nor atherosclerosis was found. The operation time was 6 hours and 13 minutes.
Microscopic examination using hematoxylin and eosin staining and elastica van Gieson staining revealed the resected tissue to be a pseudoaneurysm (). Closer observation showed intermittent disruption of the internal elastic lamina of the aneurysmal wall, known as “medial islands” (). Vacuolar degeneration of the vascular media was also observed in the surrounding small arteries. These findings suggested that a pseudoaneurysm had arisen as a result of segmental arterial mediolysis (SAM).
Fig. 2 (a, b) Microscopic examination of the aneurysmal wall using hematoxylin and eosin staining (a) and elastica van Gieson staining (b) revealed the resected aneurysm to be a pseudoaneurysm. The aneurysmal wall did not consist of vascular structure. (c) Microscopic (more ...)
The operation was completed uneventfully, and the patient recovered satisfactorily. There was no recurrence of the aneurysm visible on CT images obtained after the pseudoaneurysm resection, and good surgical results were confirmed. The patient walked without assistance when she was discharged from the hospital. Approximately 1 year after surgery, she was continuing to do well without recurrence of the aneurysms.