Appearance of the Nellix endovascular aneurysm sealing system on computed tomography: implications for postoperative imaging surveillance.

To describe the imaging characteristics of the Nellix Endovascular Aneurysm Sealing (EVAS) System on serial computed tomography (CT) surveillance. Sixty-eight patients undergoing EVAS were enrolled in a surveillance protocol that included CT scans prior to hospital discharge and at 3, 6, and 9 months postoperatively. Images were analyzed for the presence of gas within the endobag, endoleak, and for maximum radiodensity measured in Hounsfield units (HU) within the uppermost, middle, and lowermost regions of each endobag. Gas was seen within the endobags of all 68 EVAS repairs at the first postoperative CT compared with 2 (5.6%) of 36 undergoing the 3-month scan. The endobags appeared radiodense during initial imaging, and the median (interquartile range) radiodensity of the Nellix polymer decreased from 158.3 HU (149.5; 169.5) at the postoperative CT to 81.0 HU (74.0; 88.0) at 3 months, excluding 3 cases in which contrast pre-fill was utilized. Type I endoleak was seen at the periphery of the aneurysm sac or in the cleft between the endobags, with a substantially different appearance to endoleak after endovascular aneurysm repair. The evolution of CT appearances after EVAS was characteristic and predictable. The device endobags were initially radiodense, which may impact the detection of endoleak within 3 months of EVAS. Endoleaks after EVAS were seen in a different anatomical area to endoleaks after conventional stent-graft repair.

Karthikesalingam A ，de Bruin JL ，Patel SR ，Azhar B ，Rossi L ，Morgan RA ，Holt PJ ，Loftus IM ，Thompson MM ... -  《-》

Imaging After Nellix Endovascular Aneurysm Sealing: A Consensus Document.

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.

Holden A ，Savlovskis J ，Winterbottom A ，van den Ham LH ，Hill A ，Krievins D ，Hayes PD ，Reijnen MM ，Böckler D ，de Vries JP ，Carpenter JP ，Thompson MM ... -  《-》

Observations on surveillance imaging after endovascular sealing of abdominal aortic aneurysms with the Nellix system.

To describe and interpret the findings of computed tomography images acquired before and after endovascular aneurysm sealing (EVAS) with the Nellix endoprosthesis and consider the potential implications of these findings on EVAS planning and performance. A retrospective review was performed of perioperative imaging from 30 consecutive patients (median age 79 years; 19 men) undergoing elective EVAS at our center between December 2013 and November 2014. The images were systematically reviewed specifically looking for endobag collapse, aortic thrombus compression, and aortic wall disruption according to definitions set a priori. There was no perioperative mortality or endoleak after the EVAS procedure. Endobag collapse, which could potentially result in type II endoleak if occurring near a patent side branch, was seen in the endobags of 12 patients. Aortic thrombus compression, which affects the accuracy of preoperative volume measurements in predicting the amount of polymer needed to perform EVAS, was seen in 15 patients. There was one aortic wall disruption, which could potentially result in intraoperative hemorrhage, though this did not occur in this case. These observations and their potential implications should help clinicians in planning and performing EVAS, as well as in interpreting postoperative imaging.

McWilliams RG ，Fisher RK ，England A ，Torella F ... -  《-》

Endovascular Aneurysm Sealing (EVAS) and Chimney EVAS in the Treatment of Failed Endovascular Aneurysm Repairs.

Youssef M ，Zerwes S ，Jakob R ，Salem O ，Dünschede F ，Vahl CF ，Dorweiler B ... -  《-》

Management of a type Ia endoleak with the Nellix endovascular aneurysm sealing system.

To report the application of the Nellix endovascular aneurysm sealing (EVAS) device, including two chimney grafts, to successfully treat a type Ia endoleak. An 87-year-old man had an asymptomatic 7.6-cm infrarenal abdominal aortic aneurysm (AAA) and a 4.5-cm right internal iliac artery aneurysm treated using an aortouni-iliac stent-graft. Two years after the index endovascular repair, an asymptomatic type Ia endoleak was detected on duplex ultrasound; the computed tomographic angiogram (CTA) demonstrated significant sac enlargement and stent-graft migration. Initial attempts to treat the leak with 2 aortic cuffs only reduced the size of the endoleak. Another procedure was undertaken using the Nellix device with chimney grafts to increase the proximal sealing zone above the existing stent-graft. Imaging postoperatively demonstrated successful resolution of the endoleak and continuing patency of both renal artery chimney stent-grafts. CTA at 6 months demonstrated persistent sealing of the endoleak. The use of the EVAS system may represent another endovascular solution that can be added to the clinician's repertoire for treating type Ia endoleak after conventional endovascular repair of infrarenal AAA.

Hughes CO ，de Bruin JL ，Karthikesalingam A ，Holt PJ ，Loftus IM ，Thompson MM ... -  《-》