Stent Frame Movement Following Endovascular Aneurysm Sealing in the Abdominal Aorta

Abstract

Purpose. We investigated the incidence and extent of stent migration after endovascular sealing of abdominal aortic aneurysms (EVAS), its relationship with adherence to the instructions for use of the Nellix endograft and its association with aneurysm growth. Methods. In this retrospective single centre study, the clinical data and follow-up CT images of patients undergoing infra-renal EVAS with a minimum follow-up of 1 year were reviewed. The first postoperative CT scan at one month and the subsequent scans were used to measure the distances between the proximal end of the stent and reference visceral vessels using a previously validated technique. Device migration was based on the Society of Vascular Surgery definition of >10mm downward movement of either Nellix stent in the proximal landing zone; furthermore, we defined proximal displacement a downward movement of ≥4mm. Patients were categorised according to adherence to the old (2013) or new (2016) Nellix IFU. Aneurysm diameter was measured for each scan and a change of ≥5mm was deemed indicative of aneurysm growth. Results. Seventy-five patients were eligible for inclusion in our study. Over a 4-year period, migration ≥4mm occurred in 42 (56%) patients and migration of ≥10mm in 16 (21%), with similar incidence in right and left stents. Migration ≥4mm was significantly more frequent among patients whose anatomy did not conform to any IFU (p=0.025). Presence of aneurysm growth ≥5mm was observed in 14 patients (19%) and was significantly associated with proximal displacement ≥4mm (p=0.03). Conclusion. Infra-renal EVAS may be complicated by proximal displacement and migration, particularly when performed outside IFU. The definition of migration used for EVAR is inappropriate for EVAS; a new consensus on definition and measurement technique is necessary.

Introduction of New Medical Devices: Lessons Learned From Experience With Endovascular Aneurysm Sealing

“…Further data from United Kingdom and Europe supported these findings. 20,21 In light of this and in consultation with the Medicines and Healthcare Products Regulation Agency, Nellix was withdrawn from the UK market.…”

Systematic Review on the Mid-Term Outcomes of Elective Endovascular Aneurysm Sealing in Comparison to Endovascular Aneurysm Repair

“…The total of 2 EVAS studies and 3 EVAR studies were included in the analysis on graft migration ( Figure 2C ). All but 1 study 14 used >10 mm migration as their definition 13 , 15 , 16 or did not specify their cut-off value for migration. 17 , 18 For the analysis, only the migration of >10 mm was used in order to facilitate comparison, for those studies which did not specifically define migration it was assumed they used the most standard value of >10 mm.…”

“…Overview of Study Characteristics and Outcome Measures Reported per Included Study 5,[10][11][12][13][14][15][16][17][18][19][20]. …”

Nellix Endovascular Aortic Sealing Endoprosthesis Late Explantation for Concomitant Type I Endoleak and Stent Frames Proximal Caudal Migration

“…Also, vice versa the less thrombus is present in the aneurysmal sac, the more polymer can be introduced, providing support for the stents, because both blood flow downward force on the polymer-filled endobags and lateral acceleration force within curvatures in the stentgrafts could contribute to loss of proximal stent-graft attachment, which could cause a type Ia endoleak to open adjacent to the endobag. 21,22 Although proximal Nellix-in-Nellix extension possibly with chimneys can be used to treat caudally migrated endograft and consequent type Ia endoleak 23 , but this approach should be reserved to high-risk patients because the long-term efficacy remains still unproven. 24 Thus, open conversion is the safest choice.…”