Endovascular aortic sealing with Nellix reduces intraoperative radiation dose when compared to endovascular aortic repair

A Single Centre Long Term Follow Up of the Nellix Endovascular Aneurysm Sealing System

OBJECTIVE

To evaluate the clinical performance at long term follow up of endovascular aneurysm sealing (EVAS, Endologix Inc. Nellix, Irvine, CA, USA) in the treatment of abdominal aortic aneurysm (AAA).

METHODS

Observational, prospective, single centre study of primary AAA interventions with EVAS (n = 117) from November 2013 to November 2016. Endpoints were primary technical success, Nellix device failure, freedom from open surgical conversion (OSC), freedom from secondary intervention, sac rupture, total mortality, and aneurysm related mortality at long term follow up.

RESULTS

The median age was 75 years (interquartile range [IQR] 70, 81 years) and 83% were male. The median AAA diameter was 58 mm (IQR 54, 60 mm). The median length of follow up was 6.2 years (IQR 5.6, 6.8 years). Primary technical success was 100%. Median time to Nellix failure was 5.6 years (IQR 3.3, 7.4 years). Freedom from Nellix failure at five and seven years was 54% (95% confidence interval [CI] 54.2 - 63.8%) and 36% (95% CI 22.3 - 49.7%), respectively. Freedom from OSC at five and seven years was 63% (95% CI 53.2 - 72.8%) and 59% (95% CI 47 - 71%), respectively. The secondary intervention rate was 11.4/100 person years. Freedom from secondary intervention at five and seven years was 52% (95% CI 42.2 - 61.8%) and 51% (95% CI 41.2 - 60.8%), respectively. The cumulative mortality rate at five and seven years was 36% and 54%, respectively. Secondary sac rupture occurred in 9.4% (11/117) with a rate of 2/100 person years. Aneurysm related mortality was 12% (14/117) with a rate of 2.5/100 person years. The median survival was four years (IQR 3, 5.6 years). Thirty day mortality for acute OSC was 67% (n = 3) and 17.1% (6/35) for elective OSC.

CONCLUSION

Long term follow up showed an increased failure rate. Diligent surveillance after endovascular AAA treatment is mandatory, especially when promising new devices are put into clinical use.

A Meta-Analysis of Mid-Term Outcomes of Endovascular Aneurysm Sealing

BACKGROUND-AIM

Several studies have been published showing conflicting results on the outcome after endovascular aneurysm sealing (EVAS). The aim of the present study is to conduct a systematic review and meta-analysis of published evidence to assess the efficacy of EVAS in the management of patients with abdominal aortic aneurysm (AAA).

METHODS

An electronic search of the English medical literature, from 2010 to March 2021, was conducted using MEDLINE, EMBASE, and Cochrane databases to find studies relevant to outcome after EVAS.

RESULTS

The final analysis included 12 articles published between 2011 and 2021, including 1440 patients. In total, 79.3% of the included patients underwent aneurysm treatment according to the instructions for use. Technical success was 98.8%. Overall, 30-day mortality was 1.3%. Procedure-related complications were reported in 4% of the cohort. During median follow-up of 28.1 months (range 9-72 months), the pooled estimate of endoleak type I, migration and reinterventions was 16% (95% confidence interval [CI]=7-25), 16% (95% CI=9-23), and 19% (95% CI=11-28), respectively. In a sub-analysis, 7 studies (703 patients) reported outcome with a mean follow-up of more than 2 years (range 24-72 months). In these studies, the pooled estimate of endoleak type I, migration, and reinterventions was 25% (95% CI=13-38), 22% (95% CI=19-26), and 27% (95% CI=21-33), respectively.

CONCLUSION

Patients who have been treated with EVAS are in high risk for reintervention especially beyond 2 years following implantation. Close surveillance for patients treated with EVAS is mandatory.

FACTORS INFLUENCING FLUOROSCOPY TIME IN ENDOVASCULAR TREATMENT OF ABDOMINAL ANEURYSMS: A RETROSPECTIVE STUDY

Patients who undergo endovascular aortic aneurysm repair (EVAR) may require prolonged radiation exposure affected by several factors. The objectives of this study were to document fluoroscopy time (FT) during EVAR and identify possible factors that influence it. A retrospective analysis of a 180 patients' database with abdominal infrarenal aortic aneurysms submitted to EVAR during a 7-y period was performed. The FT is evaluated regarding risk factors and comorbidities, graft type and patient-related, clinical and technical parameters. FT's median (interquartile range) was 1011 (698-1500) s. Excluder and C3 Excluder were associated with significantly lower FT values when compared with other grafts. Hypertension, dyslipidemia, age ≥ 70 y, maximum aneurysm diameter ≥ 6 cm and procedure duration ≥2 h resulted in higher FT values. A significantly lower FT was found for the operations performed in the 7th y of the study's period compared with the previous 6 y, mainly because of the use of Excluder or C3 Excluder grafts. However, these grafts did not show any significant difference in FT values during the 7 y. A significant correlation between FT with age and procedure duration was found. Nevertheless, procedure duration is a poor FT predictor in linear and logistic regressions, although is significantly correlated with FT. Dyslipidemia, procedure duration and graft type are independent predictors of FT larger than the median, whereas only the procedure duration is a predictor for FT larger than the 75th percentile value. The identified factors regarding radiation protection issues should be considered when contemplating abdominal aortic aneurysm repair, however, without compromising the procedure's efficacy. Further work is necessary to identify more potential anatomical, clinical and technical factors affecting procedures' complexity and FT and patient radiation dose during EVAR interventions.

KERMA-AREA PRODUCT, ENTRANCE SURFACE DOSE AND EFFECTIVE DOSE IN ABDOMINAL ENDOVASCULAR ANEURYSM REPAIR

This study aims to evaluate patient radiation dose during fluoroscopically guided endovascular aneurysm repair (EVAR) procedures. Fluoroscopy time (FT) and kerma-area product (KAP) were recorded from 87 patients that underwent EVAR procedures with a mobile C-arm fluoroscopy system. Effective dose (ED) and organs' doses were calculated utilising appropriate conversion coefficients based on the recorded KAP values. Entrance surface dose (ESD) was calculated based on KAP values and technical parameters. The mean FT was 22.7 min (range 6.4-76.8 min), resulting in a mean KAP of 36.6 Gy cm2 (range 2.0-167.8 Gy cm2), a mean ED of 6.2 mSv (range 0.3-28.5 mSv) and a mean ESD of 458 mGy (range 26-2098 mGy). The corresponding median values were 17.4 min, 25.6 Gy cm2, 4.4 mSv and 320 mGy. The threshold of 2 Gy for skin erythema was exceeded in two procedures for a focus-to-skin distance (FSD) of 40 cm and six procedures when an FSD of 30 cm was considered. The highest doses absorbed by the adrenals, kidneys, spleen and pancreas and ranged between 3.7 and 313.3 mGy (average 66.8 mGy), 3.3 and 285.1 mGy (average 60.8 mGy), 1.3 and 111.1 mGy (average 23.7 mGy), 1.1 and 92.1 mGy (average 19.6 mGy), respectively. A wide range of patient doses was reported in the literature. The radiation dose received by the patients was comparative or lower than most of the previously reported values. However, higher doses can be revealed due to the X-ray system's non-optimum use and extended FTs, mainly affected by complex clinical conditions, patients' body habitus and vascular surgeon experience. The large variation of patient doses highlights the potential to optimise the EVAR procedure by considering the balance between the radiation dose and the required image quality. Additional studies need to be conducted in increasing the vascular surgeons' awareness regarding patient dose and radiation protection issues during EVAR procedures.

Factors affecting radiation exposure in endovascular repair of abdominal aortic aneurysms: a pilot study

BACKGROUND

Radiation exposure during endovascular repair (EVAR) of abdominal aortic aneurysms (AAAs) is a potential issue. Several studies have identified factors affecting radiation exposure, although they are limited. The aim of this study was to identify independent factors affecting radiation exposure in patients with AAA undergoing standard EVAR.

METHODS

Forty-eight consecutive patients underwent elective EVAR for infrarenal AAA managed between April 2019 and April 2020. Fluoroscopy time (FT) and kerma area product (KAP) were the main outcome measures.

RESULTS

Median (interquartile range) FT and KAP values were 1018 (653-1619) s and 2.68 (2.08-3.81) mGy·m², respectively. C3 Excluder graft use and main body insertion site from the right femoral were associated with significantly lower FT. Coronary artery disease, endografts with two docking limbs, AAA diameter, neck angle and length, procedure duration, contrast amount, and hospitalization were associated with significantly higher FT. Neck angle was the single independent perioperative factor related to FT higher than the median value observed in the study (P=0.004, odds ratio: 1.073, 95% confidence interval: 1.023-1.126). The use of the C3 Excluder device was associated with lower KAP. AAA diameter, neck angle, procedure duration, contrast medium amount and postoperative hospitalization were associated with higher KAP. AAA diameter was the single independent factor related to KAP higher than the median value observed in the study (P=0.013, odds ratio: 3.73, 95% confidence interval: 1.32-10.56).

CONCLUSIONS

This study has identified factors affecting radiation exposure during standard EVAR for infrarenal AAAs. These factors should be taken into account when contemplating AAA repair.

Progressive Device Failure at Long Term Follow Up of the Nellix EndoVascular Aneurysm Sealing (EVAS) System

OBJECTIVE

High rates of midterm failure of the Nellix EndoVascular Aneurysm Sealing (EVAS) System resulted in device withdrawal from the UK market. The study aim was to report long term Nellix EVAS outcomes and management of a failing device.

METHODS

A retrospective review of EVAS procedures at a tertiary unit was performed. Device failure was defined as a triad of stent migration, stent separation, and secondary sac expansion, or any intervention for type 1 endoleak, device rupture, or explant.

RESULTS

161 (male n = 140, female n = 21) patients with a median follow up of 6.0 (IQR 5.0-6.6) years were included. Freedom from all cause mortality estimate at six years was 41.5%. There were 70 (43.5%) device failures with a freedom from device failure estimate at six years of 32.3%. Failure was the result of sac expansion (n = 41), caudal stent migration (n = 36), stent separation (n = 26), and secondary AAA rupture (n = 15). A substantial number of type 1 endoleaks was present (1a n = 33, 1b n = 11), but the type 2 endoleak rate was low at 3.7%. Some 36 (22.4%) patients required re-intervention. Twenty-one patients underwent explant with no 30 day deaths. Six patients underwent Nellix-in-Nellix application (NINA) with one early death from bowel ischaemia and one patient who died later from non-aneurysm related cause. Two NINA patients have ongoing sac expansion and two have had thrombosis of a Nellix limb or visceral stent. Proximal embolisation was only successful in one of six cases.

CONCLUSION

The long term failure rate of Nellix EVAS is high. All patients with a device must be informed and be enrolled in enhanced surveillance. EVAS explant is an acceptable technique with favourable outcomes. Management by open explant, if the patient is fit, should be considered early and offered to those with device failure.

Editor's Choice - Comprehensive Literature Review of Radiation Levels During Endovascular Aortic Repair in Cathlabs and Operating Theatres

OBJECTIVE

Occupational exposure is a growing concern among the endovascular specialist community. Several types of imaging equipment are available, such as mobile C arms or hybrid rooms, and some have been shown to deliver higher levels of radiation. A literature review was conducted to identify studies reporting dose data during standard (EVAR) and complex abdominal aortic endovascular repair (fenestrated/branched EVAR [F/BEVAR]).

METHODS

A search of the MEDLINE and the Cochrane databases was performed by two independent investigators using the medical subject heading terms "aortic aneurysms", "radiation", and "humans" over a search period of 10 years. Studies with full text available in English and reporting radiation data independently from the imaging equipment type were included. Experimental studies were excluded.

RESULTS

The lowest dose-area product levels during EVAR and F/BEVAR were identified in hybrid rooms, while the highest were with fixed systems. When adherence to the as low as reasonably achievable principles was stipulated by the authors, dose reports tended to be among the lowest. Several studies, especially of F/BEVAR, report concerning levels of radiation for both patients and staff.

CONCLUSION

Modern imaging equipment type, team involvement with radiation management, and the support of recent imaging technologies such as fusion help to reduce the dose delivered during standard and complex EVAR. Investment in modern imaging technology should be considered in every centre providing endovascular management of aortic aneurysms.

Editor's Choice - Mid-term Migration and Device Failure Following Endovascular Aneurysm Sealing with the Nellix Stent Graft System - a Single Centre Experience

OBJECTIVE

Endovascular aneurysm sealing (EVAS) with the Nellix stent graft system is a novel concept in the management of abdominal aortic aneurysm (AAA) that aims to reduce the prevalence of all endoleaks following endovascular repair. There are few data describing the longer-term durability of this approach. The aim was to report the longer-term outcomes following EVAS in a single centre.

METHODS

This is a retrospective review of all patients that underwent Nellix at Cambridge University Hospitals Foundation Trust. Factors that are described as device failure include secondary sac rupture, graft explantation, further surgical procedures for Type 1 endoleak, or major migration of the stent grafts with pressurisation of the aortic sac.

RESULTS

A total of 161 patients have been treated with Nellix. The indications included primary AAA (n = 115), ruptured AAA (n = 4), salvage of other aortic grafts (n = 18), primary iliac aneurysm (n = 6), and chimney EVAS (ChEVAS) for pararenal AAA (n = 18). In total there have been 42 graft failures in patients treated with EVAS for primary AAA. The 4 year freedom from graft failure was 42% in patients treated for primary AAA. Failures mostly occurred more than 2 years post-Nellix implant. There were eight secondary sac ruptures (incidence 2.4 per 100 person years) and there have been 14 graft explants.

CONCLUSIONS

Failure of aneurysm sealing following treatment with Nellix has been more common than anticipated and can cause aortic rupture. Post-operative surveillance of Nellix stent grafts is crucial to identify features of failure.

The Nellix endovascular aneurysm sealing system: current perspectives

Background

The Nellix endovascular aneurysm sealing (EVAS) system is a novel approach for the treatment of abdominal aortic aneurysm (AAA). We aimed to evaluate the efficacy of EVAS in the management of patients with AAA.

Materials and methods

We searched PubMed/MEDLINE, CINAHL, and bibliographic reference lists to identify studies reporting clinical outcomes in patients with asymptomatic, non-ruptured AAA treated with EVAS with the Nellix device. We pooled dichotomous outcome data using random-effects models.

Results

We identified 14 single-arm observational studies, reporting a total of 1,510 patients. The pooled estimate of technical success was 99% (95% CI =98–100; heterogeneity: P=0.869, I²=0%). Adjunctive procedures were carried out in 39% (95% CI =19–63; heterogeneity: P<0.0001, I²=88%). Two cases of aneurysm rupture were reported within 30 days of treatment (0.7%, 95% CI =0.3–1.6; heterogeneity: P=0.923, I²=0%) and another five cases of rupture occurred during follow-up (0.8%, 95% CI =0.4–1.6; heterogeneity: P=0.958, I²=0%). The pooled estimates of early (within 30 days) and late (during follow-up) type I endoleak were 2.8 % (95% CI =1.8–4.2; heterogeneity: P=0.254, I²=18%) and 1.9% (95% CI =1.3–2.8; heterogeneity: P=0.887, I²=0%), respectively. Sac enlargement was noted in 3.1% (95% CI =1.8–5.4; heterogeneity: P=0.419, I²=0%) and device migration in 2.1% (95% CI =0.8–5.3; heterogeneity: P=0.004, I²=65%). The early and late reintervention rates were 2.7% (95% CI =1.7–4.2; heterogeneity: P=0.183, I²=27%) and 3.5% (95% CI =2.3–5.5; heterogeneity: P=0.061, I²=42%), respectively. The pooled estimate of 30-day mortality was 1.5% (95% CI =0.9–2.6; heterogeneity: P=0.559, I²=0%) and the pooled estimate of aneurysm-related death during follow-up was 1.0% (95% CI =0.6–1.9; heterogeneity: P=0.872, I²=0%).

Conclusion

Reported outcomes of EVAS are acceptable. Type I endoleak, sac enlargement, device migration, and aneurysm rupture are recognized complications. High-level research is required to investigate potential advantages of EVAS over conventional treatments.

Comparison of endovascular aneurysm sealing and repair with respect to contrast use and radiation in comparable patient cohorts

BACKGROUND

Due to recent advances in endograft design and percutaneous access, technical success could be increased during endovascular aneurysm repair (EVAR). Beside EVAR, endovascular aneurysm sealing (EVAS) provides an alternative procedure to treat aneurysms. To compare the two methods, additional benchmark criteria should be evaluated: Screening time, dose area product (DAP), procedure time and contrast use. In this study these technical variables are analyzed for EVAS vs. EVAR in comparable patient cohorts.

METHODS

It is a retrospective, single-center study. Only elective cases of infrarenal aortic aneurysms were included, all treated by the same surgeon (D.B.). Procedures were performed within the instructions for use without additional procedures. All operations were undertaken in a hybrid operating theatre. For EVAR, only the Medtronic Endurant® and the Gore C3 Excluder® were included. For EVAS the Nellix® from Endologix was used.

RESULTS

Between 2012 and 2016, 67 patients were treated with EVAS and 40 with EVAR; of these 20 and 16 could be introduced into the study respectively. Median age was 73 and 72 years respectively (only men). The two groups were comparable in terms of BMI, GFR and ASA-status. Screening time was reduced for EVAS (10.6 vs. 14.5 min., P<0.01), while the DAP was not significantly different. Procedural time and contrast use were increased for EVAS (120 vs. 96 min., 120 vs. 79 mL, P<0.01).

CONCLUSIONS

Especially the younger EVAS-procedure requires ongoing review in order to further reduce contrast agent. Reduced screening time for EVAS does not have a significant impact on radiation dose.