Abstract No. 36: Creation of Abdominal Aortic Aneurysm Using Elastase Infusion with and without an Inflammatory Modifier in Swine

PurposeTo compare two endoluminal techniques for creation of abdominal aortic aneurysms possessing characteristics such as elastin breakdown, aortic wall degradation and patent lumbar arteries in a large animal model.Materials and MethodsSwine infrarenal aortas were subjected to balloon-augmented short-term controlled-leak continuous elastase (porcine type 1) infusions without (Group 1, n =5) and with (Group 2, n=3) an inflammatory modifier (3% thioglycollate medium). In Group 2, the dose of elastase was reduced from 100 mg to 50 mg of protein. The animals were followed up to 3 weeks. Angiographic and histopathological evaluations were performed.ResultsOne Group 1 animal was acutely lost due to elastase entering a lumbar artery. In the remaining 4 animals, a mild to moderate luminal increase (112-144%) was observed at 1 week, followed at 3 weeks by aneurysm formation in 1 pig and luminal regression in 3. Histologically, the aortas had diffuse fibrosis in the tunica intima/media associated with loss of elastic fibers and smooth muscle; inflammation was observed predominantly in the adventitia. The 1 aorta that developed an aneurysm exhibited severe transmural necrosis. In Group 2, moderate to marked luminal increase (130-155%) was observed at 1 week, followed at 3 weeks by aneurysm formation in 1 pig and luminal regression in 2. One aorta perforated, but bleeding was self-limited. Histologically, all aortas showed marked transmural chronic necrotizing arteritis. A noteworthy finding in these aortas was the presence of severe mural inflammation including the formation of large abscesses.ConclusionSuccessful experimental production of aortic aneurysms appears to be associated with transmural necrosis as opposed to replacement of the aortic smooth muscle and elastic fiber network by fibrosis. Transmural fibrosis appears to restrict the formation of aneurysms. PurposeTo compare two endoluminal techniques for creation of abdominal aortic aneurysms possessing characteristics such as elastin breakdown, aortic wall degradation and patent lumbar arteries in a large animal model. To compare two endoluminal techniques for creation of abdominal aortic aneurysms possessing characteristics such as elastin breakdown, aortic wall degradation and patent lumbar arteries in a large animal model. Materials and MethodsSwine infrarenal aortas were subjected to balloon-augmented short-term controlled-leak continuous elastase (porcine type 1) infusions without (Group 1, n =5) and with (Group 2, n=3) an inflammatory modifier (3% thioglycollate medium). In Group 2, the dose of elastase was reduced from 100 mg to 50 mg of protein. The animals were followed up to 3 weeks. Angiographic and histopathological evaluations were performed. Swine infrarenal aortas were subjected to balloon-augmented short-term controlled-leak continuous elastase (porcine type 1) infusions without (Group 1, n =5) and with (Group 2, n=3) an inflammatory modifier (3% thioglycollate medium). In Group 2, the dose of elastase was reduced from 100 mg to 50 mg of protein. The animals were followed up to 3 weeks. Angiographic and histopathological evaluations were performed. ResultsOne Group 1 animal was acutely lost due to elastase entering a lumbar artery. In the remaining 4 animals, a mild to moderate luminal increase (112-144%) was observed at 1 week, followed at 3 weeks by aneurysm formation in 1 pig and luminal regression in 3. Histologically, the aortas had diffuse fibrosis in the tunica intima/media associated with loss of elastic fibers and smooth muscle; inflammation was observed predominantly in the adventitia. The 1 aorta that developed an aneurysm exhibited severe transmural necrosis. In Group 2, moderate to marked luminal increase (130-155%) was observed at 1 week, followed at 3 weeks by aneurysm formation in 1 pig and luminal regression in 2. One aorta perforated, but bleeding was self-limited. Histologically, all aortas showed marked transmural chronic necrotizing arteritis. A noteworthy finding in these aortas was the presence of severe mural inflammation including the formation of large abscesses. One Group 1 animal was acutely lost due to elastase entering a lumbar artery. In the remaining 4 animals, a mild to moderate luminal increase (112-144%) was observed at 1 week, followed at 3 weeks by aneurysm formation in 1 pig and luminal regression in 3. Histologically, the aortas had diffuse fibrosis in the tunica intima/media associated with loss of elastic fibers and smooth muscle; inflammation was observed predominantly in the adventitia. The 1 aorta that developed an aneurysm exhibited severe transmural necrosis. In Group 2, moderate to marked luminal increase (130-155%) was observed at 1 week, followed at 3 weeks by aneurysm formation in 1 pig and luminal regression in 2. One aorta perforated, but bleeding was self-limited. Histologically, all aortas showed marked transmural chronic necrotizing arteritis. A noteworthy finding in these aortas was the presence of severe mural inflammation including the formation of large abscesses. ConclusionSuccessful experimental production of aortic aneurysms appears to be associated with transmural necrosis as opposed to replacement of the aortic smooth muscle and elastic fiber network by fibrosis. Transmural fibrosis appears to restrict the formation of aneurysms. Successful experimental production of aortic aneurysms appears to be associated with transmural necrosis as opposed to replacement of the aortic smooth muscle and elastic fiber network by fibrosis. Transmural fibrosis appears to restrict the formation of aneurysms.