Current Management of the Growing Sac after Endovascular Aneurysm Repair

Kim, Yi Soo Robert

Abstract

Endovascular aneurysm repair (EVAR) has become the preferred treatment for abdominal aortic aneurysm. EVAR results in sac exclusion and subsequent sac depressurization, which prevents aneurysm rupture and aneurysm related death. Its benefits have led to a widespread adaptation. However, EVAR has transformed abdominal aortic aneurysm from an ailment with the definitive cure (open surgical repair) into a chronic disease process with the need for a close, life-long surveillance and increased potential for secondary interventions. Following EVAR, endoleak can occur, and incidence varies widely ranging from 15% to 52%. Endoleak can lead to sac growth and concern for rupture. Treatment depends on the leak type. Type I and III endoleaks should be treated. There is general consensus that type II endoleaks can be monitored except in cases of sac enlargement >5 mm. Treatment of type V endoleak, or "endotension" is controversial. These endoleaks have been associated with the first generation high porosity Gore Excluder stent graft. In these cases, relining the stent graft with resultant halt of sac growth has been descried. With the next generation of low porosity Gore Excluder, endotension is a less commonplace. Nonetheless, sac growth in the absence of endoleak can occur with any stent graft system, and surgical conversion may be warranted. Needless to say, this decision is made on an individual case basis. Management of sac growth is varied and can generally be categorized by approach (transarterial, translumbar, transcaval, and laparoscopic) or by method of repair (embolization, proximal/distal extension, endostaple, and surgical conversion). Extension pieces are used to seal type I endoleaks wheng there is adequate neck length to extend the seal. Use of fenestrated or "chimney" grafts can extend coverage to the pararenal aorta. When there is insufficient additional neck to obtain the seal, a Palmaz stent or noncompliant balloon can be considered. Recent approval of an endovascular stapler is a novel method for treating type I endoleaks. Type II endoleak treatment is conceptually similar to the treatment of a vascular malformation. An attempt should be made to embolize the inflow and outflow vessels, as well as the endoleak nidus. Laparoscopic branch vessel ligation or sac plication has been described. Finally, rather than responding to the endoleaks that occur, a strategy of preemptive action to prevent their appearance should be considered, though this is not widely practiced. Aneurysm sac "thrombization" involves embolization of the sac with a combination of glue and coil during the time of initial stent graft implantation. This may decrease the subsequent development of endoleak. Preoperative ligation or embolization of a patent inferior mesenteric artery is performed at some centers. Finally, the aforementioned endostapler can be used to prevent future endoleak and graft migration, particularly in hostile neck anatomy.