Imaging After Nellix Endovascular Aneurysm Sealing

Abstract

Endovascular aneurysm sealing (EVAS) using the Nellix system is a new and different method of abdominal aortic aneurysm repair. Normal postoperative imaging has unique appearances that change with time; complications also have different and specific appearances. This consensus document on the imaging findings after Nellix EVAS is based on the collective experience of the sites involved in the Nellix EVAS Global Forward Registry and the US Investigational Device Exemption Trial. The normal findings on computed tomography (CT), duplex ultrasound, magnetic resonance imaging, and plain radiography are described. With time, endobag appearances change on CT due to contrast migration to the margins of the hydrogel polymer within the endobag. Air within the endobag also has unique appearances that change over time. Among the complications after Nellix EVAS, type I endoleak usually presents as a curvilinear area of flow between the endobag and aortic wall, while type II endoleak is typically small and usually occurs where an aortic branch artery lies adjacent to an irregular aortic blood lumen that is not completely filled by the endobag. Procedural aortic injury is an uncommon but important complication that occurs as a result of overfilling of the endobags during Nellix EVAS. The optimum imaging surveillance algorithm after Nellix EVAS has yet to be defined but is largely CT-based, especially in the first year postprocedure. However, duplex ultrasound also appears to be a sensitive modality in identifying normal appearances and complications.

Editor's Choice – Occurrence and Classification of Proximal Type I Endoleaks After EndoVascular Aneurysm Sealing Using the Nellix™ Device

“…The diagnosis of type Ia endoleaks after EVAS can be difficult and differs from EVAR, as previously described. 11 In the present series, the endoleaks could have been detected at an earlier stage in 29% of cases. It was also shown that they tend to progress over time into more severe subtypes.…”

“…The radio density of the polymer within endobags is usually high early after implantation, rendering the early diagnosis difficult. 11 Optimal treatment modalities have also yet to be defined, although embolisation and proximal extension techniques have been suggested. The current study was conducted in order to gain more knowledge of the incidence and types of type Ia endoleak after EVAS, to assess the potential causes, and to study the treatment options.…”

Nellix stent graft migration after endovascular aneurysm sealing

“…Nevertheless, the technique is in its evolutionary phase and, in the absence of long-term experience, long-term imaging surveillance is recommended. The consensus document on imaging after EVAS with the Nellix device constitutes a guide for establishing EVAS surveillance protocols in an increasing number of vascular centres adopting this technique in their practices [4].…”

Rupture of an Infrarenal Aortic Aneurysm Due to a Secondary Type 1a Endoleak Following Endovascular Aneurysm Sealing with the Nellix<sup>®</sup> Device

“…It is known that primary type 1a endoleaks can be caused by incorrect low deployment of the Nellix devices or inadequate filling of the endobags and become larger with time when untreated [12].…”