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Abstracts: CLINICAL VIGNETTES/CASE REPORTS - COLON

A Case of Severe Ischemic Colitis in the Setting of a Type B Aortic Dissection

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Louissaint, Jeremy MD1; Wan, David W. MD2; Schneider, Yecheskel MD3

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American Journal of Gastroenterology: October 2015 - Volume 110 - Issue - p S186
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A 61-year-old male presents with a Type B aortic dissection involving the subclavian arteries, transverse aortic arch, and descending thoracic aorta. At the outside hospital, he was medically managed but represented with abdominal pain and paresthesias of the right leg. Imaging revealed new involvement of the bilateral common iliac arteries and flow studies illustrated low flow in the right renal artery. He was then transferred here for evaluation by CT surgery. Upon presentation, abdominal distension was noted, concerning for ileus secondary to acute ischemic colitis. Sigmoidoscopy displayed superficial sloughing in the splenic flexure, descending and sigmoid colon with areas of dusky-appearing mucosa, consistent with ischemia. Repairs to the descending aortic aneurysm and aortic arch as well as a right-toleft subclavian-aorto bypass were performed. The post-operative course was complicated by lactate>20, WBC>25, AST>10,000, and ALT>2000. Exploratory laparotomy revealed a perforated ischemic bowel and a subtotal colectomy, small bowel resection, and cholecystectomy were performed. Re-exploration with resection of necrotic bowel was later performed. His condition continued to deteriorate despite hemodynamic support and antibiotic therapy, and he expired 2 days later.

Aortic dissections classified in the Stanford system are either Type A or Type B. The latter includes sites not involving the ascending aorta and is associated with 30-day mortality rates of 10%; rates much less than those seen in Type A.1 The initial formation involves a tear in the vascular intima that may eventually serve as an alternate, noncommunicating conduit for blood flow. Stable Type B dissections are treated medically with methods aimed at controlling factors such as hypertension. Surgical intervention is recommended in the setting of constant/worsening pain, dissection progression, rupture, or ischemia, as these are associated with increased mortality.2 These complications can arise from the progression of the false lumen to involve branches of the aorta (renal arteries, arteries supplying visceral organs, and arteries supplying the limbs), or from hypoperfusion related to the sequestration of cardiac output; manifestations include renal failure, mesenteric ischemia, and limb ischemia, respectively.3 Preoperative mesenteric ischemia portends an unfavorable prognosis with the risk ratio of mortality >35 and an overall mortality rate as high as 87%.4

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