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Limb interventions in patients undergoing treatment with an unsupported bifurcated aortic endograft system: a review of the Phase II EVT Trial.

INTRODUCTION
Both supported and unsupported bifurcated endograft limbs develop flow-restricting lesions, including kinks, stenoses, and occlusions, which can be identified during or after surgery. Recognition and intervention are essential to achieve long-term graft patency and a satisfactory functional result. This report represents a comprehensive retrospective review of graft limb interventions from the Phase II EVT Trial with the Endovascular Grafting System unsupported bifurcated endograft (Guidant/EVT, Menlo Park, Calif).


METHODS
The study population consists of 242 patients who underwent treatment with bifurcated endografts implanted during the EVT Phase II Trial. Graft limb interventions have been divided into two groups: those in whom the intervention occurred during surgery versus those in whom the intervention occurred after surgery. Parameters studied included type, incidence, and timing of graft limb intervention, indications for intervention, procedures performed, and overall patient outcome.


RESULTS
The mean follow-up period was 31 months. Primary, primary assisted, and secondary limb patency rates were 61.6%, 93.7%, and 97.1%, respectively. Technical success rate at case completion was 97.5%. In 68 of the 242 cases, limb interventions were performed during surgery to assure patency (28.1%). In 28 cases, interventions were performed after surgery (11.6%). Of these postoperative limb problems, 82% occurred during the first 6 months. Repeat limb interventions were necessitated in three patients (1.2%). Within the intraoperative intervention group, perceived indications included kinks (15%), stenosis (57%), dissection (6%), graft redundancy (12%), and instances of twists, thrombosis, and pressure gradients (10%). These findings were successfully managed with percutaneous transluminal angioplasty only (41%), percutaneous transluminal angioplasty and stent (50%), and various combined interventions. Within the postoperative intervention group, symptomatic indications included stenosis (46%) and thrombosis/occlusion (54%). These postoperative limb events were successfully managed with stent (64%), thrombolysis (32%), and femoral-femoral bypass (21%). When limb dysfunction developed in the postoperative setting, it most often occurred within the first 6 months of implantation. Only one patient in this Phase II cohort had a lower extremity amputation unrelated to a graft limb abnormality.


CONCLUSION
The unsupported bifurcated limbs of this endograft necessitated primary adjunctive intervention in 40% of cases. Primary intervention was two times more likely to be performed at the time of the implant rather than after surgery. Repeat limb interventions were not common. Endograft limb flow problems were successfully treated with standard endovascular or surgical interventions or both. These data may support prophylactic stenting of unsupported Ancure graft limbs. A strategy that includes both intraoperative and early postoperative graft limb surveillance is essential to detect reduced limb flow.