Endovascular stent grafting in the presence of aortic neck filling defects: Early clinical experience

Objective: Although endovascular grafts have been increasingly applied to the treatment of abdominal aortic aneurysms, their use in clinical trials is limited by well-defined anatomical exclusion criteria. One such criterion is the presence of thrombus within the infrarenal neck of an aneurysm, which is thought to (1) prevent the creation of a permanent watertight seal between the graft and the vessel wall, resulting in an endoleak; (2) contribute to stent migration; and (3) increase the risk of thromboembolism. This article summarizes our experience with. endovascular abdominal aortic aneurysm exclusion in 19 patients with large aortic aneurysms, significant medical comorbidities, and apparent thrombus extending into the pararenal aortic neck. Methods: Of 268 patients undergoing abdominal aortic aneurysm repair, 19 (7%; 17 men; mean age, 71 years) demonstrated computed tomographic and angiographic evidence of intramural filling defects at the level of the aortic neck. In no instance did these filling defects extend above the renal arteries. Endovascular grafting was performed through use of a balloon-expandable Palmaz stent and an expanded polytetrafluoroethylene graft, delivered and deployed under fluoroscopic guidance. Follow-up at 3, 6, and 12 months and annually thereafter was performed with computed tomography and duplex ultrasound scan. Results: Spiral computed tomography and aortography revealed an irregular flow-limiting defect, occupying up to 75% of the aortic circumference, in every case. The mean aneurysm size, aortic neck diameter, and neck length before the procedure were 6.1, 2.43, and 1.4 cm, respectively; the mean aortic neck diameter after the procedure was 2.61 cm. No primary endoleaks were observed after graft insertion, and no delayed endoleaks have been detected during follow-up, which ranged from 7 to 48 months (mean, 23 months). In one patient, an asymptomatic renal artery embolus was detected on immediate follow-up computed tomography, and in another patient, an asymptomatic posterior tibial embolus occurred. Conclusion: No primary endoleaks, endograft migration, or significant distal embolization were observed after endografting in patients with aortic neck thrombus. The deployment of the fenestrated portion of the stent, above the thrombus and across the renal arteries, allows for effective renal perfusion, graft fixation, and exclusion of potential mural thrombus from the circulation. The presence of aortic neck thrombus may not necessarily be a contraindication to endovascular repair in select patients.