Results of endoluminal grafting in an experimental aortic aneurysm model

Abstract

We studied the impact of an endoluminally placed stented aortic graft on the geometry of a surgically created abdominal aortic dilation (AAD) in nonatherosclerotic mongrel dogs. Patulous iliac vein patch infrarenal aortoplasty produced a fusiform AAD, doubling the aorta diameter. Lumbar and mesenteric aortic tributaries were preserved and no mural thrombus formed. AADs created in 23 dogs were endoluminally excluded through transfemoral placement of a thin-wall Dacron graft 4 +/- 2 months later. Balloon-expandable stents were used to anchor each end of the graft to the aorta. The graft was crimped radially in its body and longitudinally at its ends to provide longitudinal and radial expandability in these respective zones. Serial color duplex, angiography, and direct caliper measurements were made. Before graft placement, a 19% +/- 11% diameter growth was observed. At graft placement, flow arrest immediately occurred in the space between the graft and the AAD intima in all cases. Although microscopic recanalization of the thrombus in this space was seen at sacrifice 6 and 12 months later, no macroscopic duplex flow was imaged. A 10% +/- 11% reduction in AAD diameter was measured at 6 months (p < 0.001), with no further reduction at 12 months. Graft dimensions remained stable. No anastomotic leaks developed. AAD growth stopped during the first year after effective endoluminal exclusion in normotensive dogs despite patent side branches (< 1.5 mm internal diameter) and no mural thrombus at the time of graft placement. Whether microscopic recanalization of the thrombus that forms outside the graft has an impact after 1 year remains to be seen.

Endovascular Aneurysm Repair

“…This observation is consistent with the fact that no significant shrinkage of the aneurysms was found even at 6 months of follow-up. The present study confirms the experimental data of Eton et al 28 and others 24,29 who also described such long organization processes, even if the different organization levels were not as clearly defined. Moreover, the present data are consistent with the experience in clinical patients where aneurysm shrinkage takes many months.…”

An update on the etiology of abdominal aortic aneurysms: implications for future diagnostic testing

“…The first physical model used a graft made of the inferior vena cava to replace a section of the infrarenal aorta in dogs, but the mortality rate was too high in the postoperative period to be a viable model [68][69][70][71]. To create an aneurysm that exhibited progressive sac growth, Whitbread et al used surgically interpositioned fusiform venous grafts into pig aortas [72].…”

“…The anterior patch model was another successful physical model. In this technique, an oval patch made of a number of materials, jejunal patches [73], autologous patches [69,70] and peritoneal patches [71] have been tested and found to result in consistently sized aneurysms that preserved the collaterals. Many of the physical models have little physiological relevance to the molecular pathways involved in AAA development; however, they have provided a platform for the studying other pathways like biomechanics that drive progression and rupture.…”

Experimental Models of Abdominal Aortic Aneurysms

“…also used an autologous anterior patch model in mongrel dogs to assess a specific stent graft design and delivery system [93]. Here, an iliac vein patch was used to form fuisform infrarenal aneurysms.…”