Combining Endovascular Aneurysm Sealing with Chimney Grafts - 5 Year Follow-Up after 47 Procedures

BACKGROUND

To evaluate longer-term results of a cohort treated with primary chimney endovascular aneurysm sealing (ChEVAS) for complex abdominal aortic aneurysms or secondary ChEVAS after failed endovascular aneurysm repair/endovascular aneurysm sealing.

METHODS

A single-center study was conducted of 47 consecutive patients (mean age 72 ± 8 years, range 50-91; 38 men) treated with ChEVAS from February 2014 to November 2016 and followed through December 2021. The main outcome measures were all-cause mortality (ACM), aneurysm-related mortality, occurrence of secondary complications and conversion to open surgery. Data are presented as the median (interquartile range [IQR]) and absolute range.

RESULTS

35 patients received a primary ChEVAS (=group I) and 12 patients a secondary ChEVAS (=group II). Technical success was 97% (group I) and 92% (group II); 30-day mortality was 3% and 8%, respectively. The median proximal sealing zone length was 20.5 mm (IQR 16, 24; range 10-48) in group I and 26 mm (IQR 17.5, 30; range 8-45) in group II, respectively. During a median time of follow-up of 62 months (range 0-88), ACM amounted to 60% (group I) and 58% (group II); aneurysm mortality was 29% and 8%, respectively. An endoleak was seen in 57% (group I: 15 type Ia endoleaks, four isolated type Ib, and 1 endoleak type V) and 25% (group II: 1 endoleak type Ia, one type II, and 2 type V), aneurysm growth in 40% and 17%, migration in 40% and 17%, resulting in 20% and 25% conversions in group I and II, respectively. Overall a secondary intervention was performed in 51% (group I) and 25% (group II), respectively. The occurrence of complications did not significantly differ between the 2 groups. Neither the number of chimney grafts, nor the thrombus ratio significantly affected the occurrence of abovementioned complications.

CONCLUSIONS

While initially delivering a high technical success rate, ChEVAS fails to provide acceptable longer-term results both in primary and secondary ChEVAS, resulting in high rates of complications, secondary interventions and open conversions.

The Dilemma after Sealing an Endovascular Aortic Aneurysm - Three Ways Out

INTRODUCTION

Endovascular aneurysm sealing (EVAS) was commercially introduced in 2013. The initial results of EVAS were positive, leading to its widespread use. The mid- and long-term reports showed greater than expected rates of migration, which led to a recall of the device. In the present article, we describe our experience in managing type Ia endoleaks and migration occurring with the Nellix system in three different ways: open repair with Nellix explantation, Nellix-in-Nellix application (NINA technique), and the use of the multibranched Colt device originally dedicated to the treatment of thoracoabdominal aneurysms.

MATERIALS AND METHODS

From February 2014 to June 2021, we performed 20 procedures for failed EVAS or ChEVAS (migration, type Ia endoleak, secondary aneurysm rupture). All patients treated for EVAS failure were male, aged 65 - 79.

RESULTS

Seven Nellix explantations were performed. Three patients were admitted to our hospital with ruptured aneurysms that occurred 3 weeks to 4 years (mean 124 weeks) after EVAS, and another four with type Ia endoleak. In all but one case, removal of the Nellix system was easy. In two patients, tube grafts were implanted and in the remaining five cases, bifurcated grafts were implanted. In four patients, graft legs were anastomosed with the internal iliac arteries. One patient with secondary aneurysm rupture died from multiorgan failure on the 4th postoperative day. In two cases, transient renal failure was noticed in the perioperative period. All patients were admitted to the intensive care unit for 1 to 4 days (mean 2 days). The mean hospital stay was 9 days. All patients stayed in follow-up (3 - 56 months), but no other complications occurred. Eight patients were treated with the NINA technique: five for distal migration of the Nellix and three for failed ChEVAS. Four patients had a NINA procedure performed with three chimneys, three with two and one with one chimney. In one case, two iliac limbs were implanted to avoid kinking of the external iliac arteries. The median hospitalization time after the procedure was 9 days (range 3 - 12). Four patients developed transient acute renal insufficiency in the perioperative period. The follow-up ranged between 4 and 72 months. In one patient, deterioration of preexisting chronic renal insufficiency developed 5 months after the procedure, but dialysis was not required. One patient died from exacerbation of heart failure 7 months after the NINA procedure. The Colt device was implanted in five patients for the treatment of distal migration with type Ia endoleaks. None of the patients developed any signs of spinal cord ischemia. All patients were admitted to the intensive care unit for 1 or 2 days. In two cases, transient acute renal failure was noticed in the perioperative period. The mean hospital stay was 9 days. All patients remained in follow-up (6 - 22 months). In one case, the occlusion of the celiac trunk branch was found in contrast computed tomography 1 month after implantation of the Colt device, but without any symptoms. No other complications occurred.

CONCLUSIONS

Normal strategies for the management of complications for late failure of EVAR, including stent-graft extensions, are not suitable after EVAS; therefore, alternatives are necessary. Conversion to open repair carries an extensive burden on the patient, so it is not recommended for patients with high surgical risk. The use of a Nellix-in-Nellix application to treat late failure of EVAS is not within the instructions for use but could be an effective strategy for a type Ia endoleak with or without migration. The use of this technique has been extremely limited since the Nellix system was recalled from the market. The use of the Colt multibranched device may be an alternative option, but due to the small number of patients, this method needs further evaluation.

Mid-Term Results of Endovascular Aneurysm Sealing in the Treatment of Abdominal Aortic Aneurysm With Unfavorable Morphology

PURPOSE

To report mid-term results of endovascular aneurysm sealing (EVAS) of abdominal aortic aneurysms (AAA) deemed unsuitable for a standard endovascular aneurysm repair (EVAR).

METHODS

A prospectively maintained database of 42 patients with EVAR-unfavorable anatomy treated by EVAS combined with chimney grafts in case of the proximal AAA neck shorter than 5 mm was analyzed. Early outcomes included final angiographic result, intra- and early post-operative deaths, and complications. Mid-term outcomes included all-cause mortality (ACM), aneurysm-related mortality (ARM), patency of the stents, occurrence of endoleaks, serious complications and graft failures defined as the AAA growth of more than 5 mm, type I endoleak, occlusion of the stent-graft or chimney graft, aorto-duodenal fistula, or aneurysm rupture.

RESULTS

The procedure was completed in all patients. Twenty-eight chimney grafts were implanted in 19 patients. Patients were followed for a median of 24 months (range 12-34 months). There were 2 intraoperative ruptures and 1 patient died in an early postoperative period. The cumulative ACM was 15, 21, and 36% at 12, 24, and 36 months, respectively, and the cumulative ARM was 8, 11, and 27% at 12, 24, and 36 months, respectively. Three out of 5 aneurysm-related deaths were due to a secondary aorto-duodenal fistula. The cumulative incidence of graft failure was 20, 27, and 42% at 12, 24, and 36 months, respectively. The cumulative incidence of an endoleak was 5, 9, and 23% at 12, 24, and 36 months, respectively. The graft failure increased significantly both ACM (p = .012) and ARM (p = .00003). The implantation of chimney grafts at the initial procedure increased ARM significantly (p = .008). The presence of an endoleak did not have any significant influence on ACM and ARM.

CONCLUSION

Patients treated with EVAS for AAAs with EVAR-unfavorable anatomy, especially those with chimney grafts, exhibit a high risk of graft failure and subsequent death.

Migration After Endovasclar Aneurysm Sealing in Conjunction With Chimney Grafts

Purpose

To assess the incidence of migration after endovascular aneurysm sealing (EVAS) in conjunction with chimney grafts (chEVAS) for repair of abdominal aortic aneurysms (AAAs).

Materials and Methods

A retrospective, observational cohort study was conducted of 31 patients (mean age 75.7 years; 27 men) treated for juxtarenal AAA between April 2013 and December 2018 at single centers in New Zealand and the Netherlands. The majority of patients received >1 chimney graft (13 single, 13 double, and 5 triple) during chEVAS. Six patients had only the first postoperative scan, so the migration analysis was based on 25 patients.

Results

Median seal length assessed on the first postoperative computed tomography scan was 36.5 mm. The assisted technical success rate was 93.5% with 2 technical failures. Median time to final imaging follow-up was 17 months in 25 patients. At the latest follow-up, there were no cases of caudal migration >10 mm. Freedom from caudal movement of 5 to 9 mm was estimated as 86.1% at 1 year and 73.9% at 2 years; freedom from clinically relevant migration (movement requiring reintervention) was 100% at both time intervals. However, at 3 years there were 2 cases of caudal movement of 5 to 9 mm and a type Ia endoleak warranting reintervention. No correlation between migration and aneurysm growth (p=0.851), endoleak (p=0.562), or the number of chimney grafts (p=0.728) was found. During follow-up, 2 patients (7%) had aneurysm rupture and 10 (33%) had reinterventions. Eight patients (27%) died; 2 were aneurysm-related (7%) and due to the consequences of a reintervention.

Conclusion

In the 2 years following chEVAS, there was no caudal migration >10 mm, but nearly a quarter of patients had caudal movement of 5 to 9 mm. A trend was observed toward ongoing migration that required intervention at 3-year follow-up. chEVAS is technically challenging and should be considered only for patients with no viable alternative treatment option.

Electrocardiography-gated computed tomography angiography analysis of cardiac pulsatility-induced motion and deformation after endovascular aneurysm sealing with chimney grafts

OBJECTIVE

To evaluate the proximal stability of the chimney endovascular aneurysm sealing configuration (chEVAS) during the cardiac cycle by investigating the cardiac pulsatility-induced movement and deformation.

METHODS

We retrospectively analyzed postoperative electrocardiogram-gated computed tomography angiography scans of 11 chEVAS cases (9 primary chEVAS plus 2 chEVAS-in-chEVAS). ChEVAS procedures were conducted between September 2013 and June 2016. Motion and deformation of the EVAS stents, the chimney grafts, and the stented branch vessels were evaluated during the cardiac cycle using an established combination of image registration and segmentation techniques.

RESULTS

Electrocardiogram-gated computed tomography angiography scans of 11 chEVAS configurations including 22 EVAS stents and 20 chimney grafts were analyzed. The three-dimensional displacement was at most 1.7 mm for both the EVAS stents and the chimney grafts. The maximum change in distance between components was no more than 0.4 mm and did not differ between EVAS-to-EVAS stent and EVAS stent-to-chimney stent (0.2 ± 0.1 mm vs 0.2 ± 0.1 mm; P = .823). The mean change in chimney deflection angle was 1.2 ± 0.7°; the maximum change was greatest for the superior mesenteric artery (SMA) (2.6°). The EVAS stent-to-chimney angles for the left renal artery, right renal artery, and SMA varied on average by 0.7 ± 0.3° (range, 0.4°-1.3°), 1.0 ± 0.3° (range, 0.5°-1.7°), and 0.8 ± 0.4° (range, 0.3°-1.3°), respectively, during the cardiac cycle. The end-stent angles for the left renal artery, right renal artery, and SMA varied on average by 1.7 ± 0.9° (range, 0.5°-3.3°), 1.9 ± 0.8° (range, 0.7°-3.3°), and 1.3 ± 0.4° (range, 0.7°-1.6°), respectively, during the cardiac cycle. Overall, the end-stent angles varied on average by 1.7 ± 0.8° (range, 0.5°-3.3°).

CONCLUSIONS

The chEVAS configuration proved to be stable during the cardiac cycle, as demonstrated by minimal cyclical changes in distance between device components and angulation between the EVAS stents and the chimney grafts. The limited deflection angles of the chimney grafts decrease the risk of bending fatigue, but the more apparent change in end-stent angle distal to the chimney graft may raise concerns regarding late branch occlusion or stenosis.

Acute Kidney Injury after Complex Endovascular Aneurysm Repair

Background:

Complex endovascular repair of abdominal aortic aneurysm carries higher perioperative morbidity than standard infrarenal endovascular repair.

Objective:

This study reviews the incidence and associated factors of acute kidney injury in complex aortic endovascular repair of juxtarenal, pararenal, and thoracoabdominal aortic aneurysms.

Methods:

A literature review was performed for all studies on the endovascular repair of juxtarenal, pararenal, and thoracoabdominal aneurysms that evaluated rates of acute kidney injury as an outcome. Outcomes were further analyzed by the level of anatomic complexity and method of repair.

Results:

52 studies met inclusion criteria, with a total of 5454 individuals undergoing repair from 2004 to 2017. The overall rate of acute kidney injury ranged widely from 0 to 41%, with a rate of hemodialysis from 0 to 19% (temporary) and 0 to 14% (permanent). Increasing anatomic complexity was associated with higher rates of acute kidney injury. Mode of endovascular repair, learning curve effect, and preoperative chronic renal insufficiency did not demonstrate any associations with the outcome.

Conclusion:

Published rates of acute kidney injury in complex aortic aneurysm repair vary widely with few definitively associated factors other than increasing anatomic complexity and operative time. Further study is needed for the identification of predictors related to postoperative acute kidney injury.

Quantitative Stent Graft Motion in ECG Gated CT by Image Registration and Segmentation: In Vitro Validation and Preliminary Clinical Results

OBJECTIVES

The dynamic endovascular environment of stent grafts may influence long term outcome after endovascular aneurysm repair (EVAR). The sealing and fixation of a stent graft to the aortic wall is challenged at every heartbeat, yet knowledge of the cardiac induced dynamics of stent grafts is sparse. Understanding the stent-artery interaction is crucial for device development and may aid the prediction of failure in the individual patient. The aim of this work was to establish quantitative stent graft motion in multiphasic electrocardiogram (ECG) gated computed tomography (CT) by image registration and segmentation techniques.

METHODS

Experimental validation was performed by evaluating a series of ECG gated CT scans of a stent graft moving at different amplitudes of displacement at different virtual heart rates using a motion generating device with synchronised ECG triggering. The methodology was further tested on clinical data of patients treated with EVAR devices with different stent graft designs. Displacement during the cardiac cycle was analysed for points on the fixating stent rings, the branches or fenestrations, and the spine.

RESULTS

Errors for the amplitude of displacement measured in vitro at individual points on the wire frame were at most 0.3 mm. In situ cardiac induced displacement of the devices was found to differ per location and also depended on the type of stent graft. Displacement during the cardiac cycle was greatest in a fenestrated device and smallest in a chimney graft sac anchoring endosystem, with maximum displacement varying from 0.0 to 1.4 mm. There was no substantial displacement measurable in the spine.

CONCLUSIONS

A novel methodology to quantify and visualise stent graft motion in multiphasic ECG gated CT has been validated in vitro and tested in vivo. This methodology enables further exploration of in situ motion of different stent grafts and branch stents and their interaction with native vessels.

Cardiac Pulsatility- and Respiratory-Induced Deformations of the Renal Arteries and Snorkel Stents After Snorkel Endovascular Aneurysm Sealing

Purpose: To quantify deformations of renal arteries and snorkel stents after snorkel endovascular aneurysm sealing (Sn-EVAS) resulting from cardiac pulsatility and respiration and compare these deformations to patients with untreated abdominal aortic aneurysms (AAA) and snorkel endovascular aneurysm repair (Sn-EVAR). Materials and Methods: Ten Sn-EVAS patients (mean age 75±6 years; 8 men) were scanned with cardiac-gated, respiration-resolved computed tomography angiography. From 3-dimensional geometric models, changes in renal artery and stent angulation and curvature due to cardiac pulsatility and respiration were quantified. Respiration-induced motions were compared with those of 16 previously reported untreated AAA patients and 11 Sn-EVAR patients. Results: Renal artery bending at the stent end was greater for respiratory vs cardiac influences (6°±7° vs -1°±2°, p<0.025). Respiration caused a 3-fold greater deformation on the left renal artery as compared with the right side. Maximum curvature change was higher for respiratory vs cardiac influences (0.49±0.29 vs 0.24±0.17 cm^-1, p<0.025), and snorkel renal stents experienced similar maximum curvature change due to cardiac pulsatility and respiration (0.14±0.10 vs 0.19±0.09 cm^-1, p=0.142). When comparing the 3 patient cohorts for respiratory-induced deformation, there was significant renal branch angulation in untreated AAAs, but not in Sn-EVAR or Sn-EVAS, and there was significant bending at the stent end in Sn-EVAR and Sn-EVAS. Maximum curvature change due to respiration was ~10-fold greater in Sn-EVAR and Sn-EVAS compared to untreated AAAs. Conclusion: The findings suggest that cardiac and respiratory influences may challenge the mechanical durability of snorkel stents of Sn-EVAS; similarly, however, respiration may be the primary culprit for tissue irritation, increasing the risk for stent-end thrombosis, especially in the left renal artery. The bending stiffness of snorkel stents in both the Sn-EVAR and Sn-EVAS cohorts damped renal branch angulation while it intensified bending of the artery distal to the snorkel stent. Understanding these device-to-artery interactions is critical as they may affect mechanical durability of branch stents and quality and durability of treatment.

Secondary Endovascular Aneurysm (EVAS) Sealing in Combination With Chimney Grafts to Treat Failed Chimney EVAS

Purpose: To describe a proximal extension of a failed chimney endovascular aneurysm sealing repair (chEVAS) using a chEVAS-in-chEVAS procedure in 2 cases with successful treatment outcome at 2-year follow-up. Case Report: Two patients with an infrarenal abdominal aortic aneurysm were treated with an elective chEVAS procedure with 1 chimney stent for a unilateral renal artery. At 18 and 24 months, respectively, both patients showed aneurysm growth with an associated decrease in proximal seal. Both patients were treated with a secondary chEVAS procedure, consisting of chimney stent-graft placement in the contralateral renal and the superior mesenteric arteries combined with proximal extension of the in situ chimney stent-graft and the Nellix stents. Two-year follow-up demonstrated successful aneurysm exclusion with a patent stent configuration. Conclusion: A type Ia endoleak after chEVAS can be successfully repaired with a chEVAS-in-chEVAS procedure.

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.

Secondary Endovascular Aneurysm (EVAS) Sealing in Combination With Chimney Grafts to Treat Failed Chimney EVAS

PURPOSE

To describe a proximal extension of a failed chimney endovascular aneurysm sealing repair (chEVAS) using a chEVAS-in-chEVAS procedure in 2 cases with successful treatment outcome at 2-year follow-up.

CASE REPORT

Two patients with an infrarenal abdominal aortic aneurysm were treated with an elective chEVAS procedure with 1 chimney stent for a unilateral renal artery. At 18 and 24 months, respectively, both patients showed aneurysm growth with an associated decrease in proximal seal. Both patients were treated with a secondary chEVAS procedure, consisting of chimney stent-graft placement in the contralateral renal and the superior mesenteric arteries combined with proximal extension of the in situ chimney stent-graft and the Nellix stents. Two-year follow-up demonstrated successful aneurysm exclusion with a patent stent configuration.

CONCLUSION

A type Ia endoleak after chEVAS can be successfully repaired with a chEVAS-in-chEVAS procedure.

Identifying and addressing the limitations of EVAR technology

INTRODUCTION

Endovascular aortic repair (EVAR) has improved over the last two decades. Approximately 80% of the patients presenting with an abdominal aortic aneurysm (AAA) is nowadays primarily treated with EVAR.

AREAS COVERED

In this review, the differences between endovascular and open repair, the clinical characteristics needed for EVAR, the role of clinical imaging and the developments in EVAR technology will be discussed. Early mortality is lower in EVAR as compared to open repair, whereas this benefit is lost after 3 years postoperatively. EVAR comes with a high reintervention rate, with endoleak being the most important predictive factor for reintervention. Expanding technical possibilities have allowed surgeons to choose from a palate of endovascular approaches in aneurysm patients with challenging anatomies.

EXPERT COMMENTARY

Although EVAR has taken a giant leap forward in development, the new developments have seemed to surpass the long-term limitations with older devices. It is important to start focusing on the current limitations of EVAR, in particular the durability of devices in the human variable anatomic and dynamic environment.

Anatomical Applicability of Endovascular Aneurysm Sealing Techniques in a Consecutive Cohort of Fenestrated Endovascular Aneurysm Repairs

PURPOSE

To determine how many endovascular aneurysm sealing (EVAS) procedures with/without off-label use of chimneys (ChEVAS) could have been performed in a cohort of patients who had undergone fenestrated endovascular aneurysm repair (FEVAR).

METHODS

Sixty patients (median age 76.3 years; 54 men) who underwent FEVAR in our institution between 2013 and 2015 were selected for the study. The median aneurysm diameter was 62.0 mm (interquartile range 59.3, 69.0). Preoperative computed tomography angiograms (CTA) were anonymized and sent to 2 physicians with experience of more than 40 ChEVAS interventions. These ChEVAS planners were blinded to the study purpose and asked to agree upon an EVAS/ChEVAS plan. The primary outcome was the percentage of the FEVAR patients in whom an EVAS/ChEVAS was technically possible. The secondary outcomes were a comparison of seal zones, number of target vessels, and device cost.

RESULTS

An EVAS-based intervention would have been technically possible in 56 (93.3%) of the FEVAR patients. The median proximal aortic seal zone was significantly more distal in the EVAS/ChEVAS procedures vs the FEVAR cases (zone 8 vs zone 7, p<0.001) and fewer target vessels were involved (median 2 vs 3, p<0.001). The cost of the EVAS/ChEVAS device was 66% of the FEVAR device. Planners would not currently advocate an EVAS-based intervention in 43 (76.8%) of these 56 patients due to concerns regarding the risk of migration associated with the lumen thrombus ratios observed.

CONCLUSION

EVAS is technically feasible in the majority of patients undergoing FEVAR in our institution but currently advocated in only 23.2%. The seal zone was more distal, fewer target vessels were involved, and the device cost was lower in the planned EVAS/ChEVAS interventions.