A 65-year-old man with a history of hypertension, type 2 diabetes mellitus, and tobacco smoking comes to the office reporting mild back pain. Abdominal examination reveals a bruit, but no pulsatile mass is palpated. Femoral and pedal pulses are symmetric. The patient is sent for ultrasound and is found to have a large infrarenal abdominal aortic aneurysm. Open aneurysm repair is performed. During the procedure, the inferior mesenteric artery is ligated, the diseased portion of the aorta is dissected, and a graft is placed from below the renal arteries to the bifurcation of the aorta. Collateral circulation from which of the following vessels is most likely responsible for preventing ischemia of the descending colon?

Question

A 65-year-old man with a history of hypertension, type 2 diabetes mellitus, and tobacco smoking comes to the office reporting mild back pain.  Abdominal examination reveals a bruit, but no pulsatile mass is palpated.  Femoral and pedal pulses are symmetric.  The patient is sent for ultrasound and is found to have a large infrarenal abdominal aortic aneurysm.  Open aneurysm repair is performed.  During the procedure, the inferior mesenteric artery is ligated, the diseased portion of the aorta is dissected, and a graft is placed from below the renal arteries to the bifurcation of the aorta.  Collateral circulation from which of the following vessels is most likely responsible for preventing ischemia of the descending colon?

Quizplus · Accepted Answer

11ec160b_357b_a722_9249_c7776716af3f_MD0001_00 The gastrointestinal tract receives its blood supply from 3 main arteries: The celiac trunk supplies the stomach, part of the duodenum, gallbladder, liver, spleen, and pancreas (Choice A). The SMA and IMA are the 2 main vessels supplying the small and large intestines and are connected by a pair of anastomoses: the marginal artery of Drummond, which is the principal anastomosis, and the inconsistently present arc of Riolan (mesenteric meandering artery). These anastomoses protect the intestines from ischemia and, due to the marginal artery, the IMA is not always reconnected during aortic aneurysm repair. (Choice B) The external iliac artery supplies the inferior epigastric artery and the deep circumflex iliac artery before becoming the femoral artery. Although the inferior epigastric artery anastomoses with the superior epigastric artery, these provide blood supply to the abdominal wall, not the intestines. (Choices C and E) The inferior vena cava (IVC) has little role in the direct drainage of the intestines except from the rectum, which partially drains via the middle and inferior rectal veins into the internal iliac veins. The remainder of the venous drainage occurs via the superior and inferior mesenteric veins, which drain into the portal vein. After perfusing the liver, the portal vein drains into the IVC via the hepatic veins. (Choice D) The internal iliac artery supplies part of the rectum via the middle rectal artery. An anastomosis exists between the superior and middle rectal arteries, which can help prevent rectal ischemia after IMA occlusion. However, the SMA is more likely to prevent ischemia in the descending colon due to its proximity and the extensive collateral arcades between the SMA and IMA. (Choice F) Although the renal arteries arise from the abdominal aorta just inferior to the SMA, they do not provide collateral circulation to the intestines. Educational objective: The superior mesenteric artery and inferior mesenteric artery are the 2 main vessels supplying the small and large intestines. They are connected by a pair of anastomoses: the marginal artery of Drummond, which is the principal anastomosis, and the inconsistently present arc of Riolan (mesenteric meandering artery). __________ References: Clinical interest of digestive arterial trunk anastomoses. (http://www.ncbi.nlm.nih.gov/pubmed/16547602) Rare case of "wandering artery of drummond" as a result of chronic triple mesenteric vessel occlusion treated by isolated angioplasty and stenting of the inferior mesenteric artery. (http://www.ncbi.nlm.nih.gov/pubmed/24436621)

A 65-Year-Old Man with a History of Hypertension, Type 2