Type 2 Endoleaks after Abdominal Aortic Aneurysm Stent Grafting with Systematic Mesenteric and Lumbar Coil Embolization

Feasibility of aortic aneurysm sac embolization using a novel shape memory polymer embolic device

BACKGROUND

We investigated the feasibility of aneurysm sac embolization using a novel self-expanding porous shape memory polymer (SMP) device during endovascular aortic abdominal or thoracic aneurysm repair (EVAR).

METHODS

Retrospective analysis of consecutive patients treated at 2 centers in Germany. Patients were treated from January 2019 to July 2021 with follow-up at 7 days and 3, 6, and 12 months. Aneurysm sacs were implanted with SMP devices immediately following endograft placement during the same procedure. Primary endpoint was technically successful SMP-device deployment into the aneurysm sac outside the endograft. Secondary endpoints were changes in aneurysm volume and associated complications (e.g., endoleaks).

RESULTS

We included 18 patients (16 males), aged 72 ± 9 years, achieving 100% technical success. Mean preprocedure aortic aneurysm sac volume was 195 ± 117 mL with a perfused aneurysm volume of 97 ± 60 mL. A mean of 24 ± 12 SMP devices per patient were used (range 5-45, corresponding to 6.25-56.25 mL expanded embolic material volume). All evaluable patients exhibited sac regression except 2 patients yet to reach 3-month follow-up. At mean 11 ± 7 months (range 3-24), change in aneurysm volume from baseline was -30 ± 21 mL (p < 0.001). In 8 patients, aneurysm regression was observed despite type 2 endoleaks in 6 and type 1A endoleaks in 2, none of them requiring further intervention to date. No morbidity or mortality related to this treatment occurred.

CONCLUSIONS

SMP devices for aortic aneurysm sac embolization during endovascular repair appear feasible and safe in this small case series. Prospective studies are needed.

KEY POINTS

• Shape memory polymer is a novel, self-expanding, porous, and radiolucent embolic device material. • Aortic aneurysm sacs were treated with polymer devices immediately following endograft placement. • Aortic aneurysm sac regression was observed in all patients with over 3-month follow-up. • Aortic aneurysm sac regression was observed even in the presence of endoleaks.

Systematic review and network meta-analysis of pre-emptive embolization of the aneurysm sac side branches and aneurysm sac coil embolization to improve the outcomes of endovascular aneurysm repair

Objective

Previous reports have revealed a high incidence of type II endoleak (T2EL) after endovascular aneurysm repair (EVAR). The incidence of T2EL after EVAR is reduced by pre-emptive embolization of aneurysm sac side branches (ASSB) and aneurysm sac coil embolization (ASCE). This study aimed to investigate whether different preventive interventions for T2EL were correlated with suppression of aneurysm sac expansion and reduction of the re-intervention rate.

Methods

The PubMed, Web of Science, MEDLINE and Embase databases, and conference proceedings were searched to identify articles on EVAR with or without embolization. The study was developed in line with the Participants, Interventions, Comparisons, Outcomes, and Study design principles and was conducted and reported in accordance with the Preferred Reporting Items for Systematic reviews and Meta-Analyses guidelines. We used network meta-analysis based on multivariate random-effects meta-analysis to indirectly compare outcomes of different strategies for embolization during EVAR.

Results

A total of 31 studies met all inclusion criteria and were included in the qualitative and quantitative syntheses. The included studies were published between 2001 and 2022 and analyzed a total of 18,542 patients, including 1,882 patients who received prophylactic embolization treatment during EVAR (experimental group) and 16,660 who did not receive prophylactic embolization during EVAR (control group). The effect of pre-emptive embolization of the inferior mesenteric artery (IMA) (IMA-ASSB) in preventing T2EL was similar (relative risk [RR] 1.01, 95% confidence interval [CI] 0.38–2.63) to the effects of non-selective embolization of ASSB (NS-ASSB) and ASCE (RR 0.88, 95% CI 0.40–1.96). IMA-ASSB showed a better clinical effect in suppressing the aneurysm sac expansion (RR 0.27, 95% CI 0.09–2.25 compared with NS-ASSB; RR 0.93, 95% CI 0.16–5.56 compared with ASCE) and reducing the re-intervention rate (RR 0.34, 95% CI 0.08–1.53 compared with NS-ASSB; RR 0.66, 95% CI 0.19–2.22 compared with ASCE). All prophylactic embolization strategies improved the clinical outcomes of EVAR.

Conclusion

Prophylactic embolization during EVAR effectively prevents T2EL, suppresses the aneurysm sac expansion, and reduces the re-intervention rate. IMA embolization demonstrated benefits in achieving long-term aneurysm sac stability and lowering the risk of secondary surgery. NS-ASSB more effectively reduces the incidence of T2EL, while IMA embolization alone or in combination with ASCE enhances the clinical benefits of EVAR. In addition, as network meta-analysis is still an indirect method based on a refinement of existing data, more studies and evidence are still needed in the future to establish more credible conclusions.

[The Prophylaxis of Type 2 Endoleaks is Relevant for Long Term Success of EVAR]

One out of 8 patients needs a reintervention after EVAR during the first 5 years. Two thirds of secondary interventions aim at treating endoleaks. The prevalence of complications doubles in the presence of endoleaks. Fourth generation stent grafts do not lead to a decrease in Type 2-associated reinterventions, but to better prevention of Type 1 and 3 endoleaks. Pretreatment of potential type 2 feeding arteries with embolising agents and treatment of the occurrence of type 2 endoleaks.

Effectiveness of collateral arteries embolization before endovascular aneurysm repair to prevent type II endoleaks: A systematic review and meta-analysis

OBJECTIVES

This study aimed to evaluate the effect of preventive collateral arteries embolization before endovascular aneurysm repair (EVAR) to reduce type II endoleaks (T2EL), aneurysm enlargement, and re-interventions.

METHODS

A comprehensive search of PubMed, MEDLINE, Web of Science, and Embase was conducted to identify articles in English, related to preventive collateral arteries embolization before EVAR, published until October 2020.

RESULTS

A total of 12 relevant studies, including 11 retrospective studies and one randomized controlled trial, were identified and fulfilled the specified inclusion criteria. A total of 1706 patients in 11 studies were involved in the meta-analysis. The overall incidence of T2EL was 17.3% in the embolization group vs. 34.5% in the control group (OR 0.36, p < 0.01). The incidence of persistent T2EL was 15.3% vs. 30.0% (OR 0.37, p < 0.01). Five studies reported the incidence of sac enlargement, with the rate 10.2% vs. 24.9% (OR 0.25, p < 0.01). Nine studies reported T2EL related re-interventions, and it was 1.3% in the embolization group and 10.4% in control (OR 0.14, p < 0.01). The technical success of collateral arteries embolization was 92.1% (455/494) in the 12 studies. 1.2% (10/829) patients suffered a mild complication of collateral arteries embolization, and 2/829 patients died because of the embolization.

CONCLUSION

Collateral arteries embolization is a promising measure to prevent the occurrence of T2EL, sac enlargement, and re-intervention. High-quality studies need to be conducted to provide stronger evidence-based medical suggestions about the embolize operation.

Clinical Comparison between Early and Late Spontaneous Sac Shrinkage after Endovascular Aortic Aneurysm Repair

BACKGROUND

Early spontaneous shrinkage (ESS) of abdominal aortic aneurysm (AAA) within 1 year after endovascular aortic aneurysm repair (EVAR) could be a predictor of durable success. However, late spontaneous shrinkage (LSS) during longer follow-up has not been well addressed. We compared late complications of ESS and LSS.

METHODS

Our series of elective EVAR for infrarenal AAA from June 2007 to December 2017 was reviewed. Patients with ≥1 year of follow-up with computed tomography (CT) studies were included. Patients with any reintervention within 1 year were excluded. Spontaneous shrinkage (SpS) was defined as a diameter reduction ≥10 mm without any reintervention. ESS was defined as SpS within 1 year, and LSS was defined as SpS occurring after 1 year of follow-up. Aneurysms that became larger than the original size after SpS were defined as re-expansion. Late complications (re-expansion, reintervention, and aneurysm-related death) and related factors were compared between ESS and LSS.

RESULTS

A total of 495 patients were enrolled. Median follow-up was 43 months [24-67, interquartile range (IQR)]. Among patients, 126 ESS and 55 LSS occurred. The cumulative rates of SpS were 25.7±2.0%, 37.4±2.4%, and 47.3±3.7% at 1, 3, and 7 years, respectively. There was 1 re-expansion and 6 reinterventions during further follow-up after SpS. The rates of freedom from late complications at 5 years were not significantly different between ESS (89.2±4.0%) and LSS (95.8±4.1%) (P = 0.465). Regression analysis revealed that the Zenith device was significantly related to ESS compared to the Excluder (P = 0.006) and Endurant (P = 0.040) . More than 6 preoperative patent lumbar arteries negatively correlated with ESS (P = 0.023). However, these factors had no significant impact on LSS.

CONCLUSIONS

The rates of late complications after SpS were comparable between ESS and LSS. Patients with delayed sac shrinkage with a reduction in diameter ≥10 mm should expect the same durable success as patients with quick shrinkage.

Endovascular aneurysm sealing addresses several limitations of conventional endovascular aneurysm repair

Endovascular aneurysm repair has enabled a broad population of patients with infrarenal abdominal aortic aneurysm to be treated by a less-invasive technique. However, endovascular aneurysm repair has therapeutic limitations, including the need for lifelong surveillance and a higher rate of secondary interventions than open repair. These outcomes can promote patient dissatisfaction and result in increased health care costs and associated morbidity and mortality. The primary reason for secondary interventions is continued abdominal aortic aneurysm sac enlargement due to endoleaks. Conventional endovascular aneurysm repair procedures do not address aortic branch vessels that are ligated during open repairs. Secondary measures to occlude these branch vessels have shown efficacy in limiting sac growth, but do not predictably eliminate the need for further interventions. Endovascular aneurysm sealing is a new technique that addresses some of the limitations of conventional endovascular repair. Endovascular aneurysm sealing secures the stent graft flow lumens within a biostable polymer. This stability prevents stent migration while also sealing branch vessels that are otherwise not addressed by other endovascular devices. This new approach to endovascular repair has shown early promise in reducing the rates of endoleak and need for secondary interventions, while opening up the possibility of durable endovascular repair to a more challenging type of anatomy.

Preoperative Inferior Mesenteric Artery Embolization: A Valid Method to Reduce the Rate of Type II Endoleak after EVAR?

BACKGROUND

Type II endoleak is the most commonly encountered endoleak after endovascular abdominal aortic aneurysm repair (EVAR). Some have advocated preoperative inferior mesenteric artery (IMA) embolization as a valid method for reducing the incidence of this endoleak, but controversies exist. We sought to demonstrate the impact of IMA embolization using a meta-analysis of currently available studies combined with our own experience.

METHODS

We conducted an institutional review board-approved, retrospective analysis of all patients undergoing IMA embolization before EVAR between the years 2010 and 2015 and used as a control a similar group of patients with patent IMA. We divided patients from our own experience and 5 other studies into 2 groups: those who did not undergo IMA embolization (control) before EVAR and those who did. Rates of type II endoleaks, aneurysm sac regression, and secondary interventions were analyzed.

RESULTS

A total of 620 patients from 6 studies were analyzed, including 258 patients who underwent an attempted IMA embolization before EVAR with a cumulative success rate of 99.2% (range, 93.8% to 100%). There was 1 fatality associated with IMA embolization. A meta-analysis showed that preoperative IMA embolization protected against type II endoleaks compared to the control group (odds ratio [OR], 0.31 [0.17-0.57]; P < 0.001, I² = 43%). Furthermore, the rate of secondary intervention was significantly lower in the treatment group (OR, 0.12 [0.004-0.36]; P < 0.001, I² = 0%). After IMA embolization, type II endoleak resulted from patent lumbar arteries in all 62 patients with persistent endoleak.

CONCLUSIONS

Preoperative embolization of the IMA protects against the development of type II endoleaks and secondary interventions and may potentially lead to a rapid aneurysm sac regression. The procedure can be performed with a high technical success rate and minimal complications and should be considered in patients with IMA >3 mm before EVAR. A randomized trial, however, is required to clearly delineate the clinical significance of this technique.

Characteristics and Risk Factors for Type 2 Endoleak in an East Asian Population From a Japanese Multicenter Database

BACKGROUND

Clinically distinct differences exist between East Asian and Caucasian subjects, but data for type 2 endoleak (T2EL) are limited in the East Asian population. The aim of this study was to analyze the characteristics of East Asian T2EL using a Japanese multicenter database.

METHODS AND RESULTS

Retrospective analysis of 832 endovascular aneurysm repairs performed from 2008 to 2014 were conducted. T2EL was observed in 234 cases (28.1%), and in 32 cases (3.8%) it led to sac expansion >5 mm caused by isolated T2EL (median follow-up, 35.6 months). On univariate and multivariate analysis, non-smoker status (odds ratio [OR], 2.216; P<0.001), Excluder stent graft (OR, 2.027; P<0.001), and T2EL at final angiogram (OR, 2.080; P<0.001) were risk factors for T2EL. On multivariate analysis for isolated T2EL with sac expansion, only non-smoker status remained (OR, 2.671; P<0.001). Other than T1EL, isolated T2EL was the most significant risk factor for sac expansion (OR, 18.486; P<0.001). Furthermore, out of 11 transarterial embolization procedures initiated, 4 led to rupture during follow-up.

CONCLUSIONS

East Asian T2EL had a strong relationship with non-smoker status. Also, T2EL was a significant risk factor for sac expansion, which sometimes led to rupture even after intervention. Along with the high prevalence of T2EL observed, East Asian T2EL may not always be benign.

Essentials of endovascular abdominal aortic aneurysm repair imaging: postprocedure surveillance and complications

OBJECTIVE

Lifelong postprocedural imaging surveillance is necessary after endovascular abdominal aortic aneurysm repair (EVAR) to assess for complications of endograft placement, as well as device failure and continued aneurysm growth. Refinement of the surveillance CT technique and development of ultrasound and MRI protocols are important to limit radiation exposure.

CONCLUSION

A comprehensive understanding of EVAR surveillance is necessary to identify life-threatening complications and to aid in secondary treatment planning.

Type 2 Endoleaks Post-EVAR: Current Evidence for Rupture Risk, Intervention and Outcomes of Treatment

Type 2 endoleaks (EL2) are the most commonly encountered endoleaks following EVAR. Despite two decades of experience, there remains considerable variation in the management of EL2 with controversies ranging from if to treat, when to treat and how to treat. Here, we summarise the available evidence, describe the treatment techniques available and offer guidelines for management.

CT Findings of Risk Factors for Persistent Type II Endoleak from Inferior Mesenteric Artery to Determine Indicators of Preoperative IMA Embolization

PURPOSE

To identify the computed tomography (CT) findings of persistent type II endoleak from the inferior mesenteric artery (IMA) which indicate the need for preoperative IMA embolization.

MATERIALS AND METHODS

Included were 120 patients (96 males, 49-93 years old, mean: 77.7) who underwent endovascular aortic aneurysm repair (EVAR) between June 2007 and October 2010. The relationship between persistent type II endoleak and CT findings of IMA orifice was examined.

RESULTS

CT showed no type II endoleak from IMA in 106 patients (89%; Group N), and transient type II endoleak from IMA in 10 patients (8.3%; Group T). CT showed persistent type II endoleak from IMA in 4 patients (3.3%; Group P) and three of them underwent reintervention. Univariate Cox-Mantel test analysis indicated that stenosis (p = 0.0003) and thrombus (p = 0.043) in IMA orifice were significant factors for persistent type II endoleak. The ratios of patients with proximal IMA more than 2.5 mm diameter in Groups N, Y, and P were 26/106 (24%), 5/10 (50%) and 4/4 (100%), respectively.

CONCLUSION

Indicators for embolization of IMA prior to EVAR for the prevention of type II endoleak appear to be: (1) more than 2.5 mm in diameter and (2) no stenosis due to calcification or mural thrombus in IMA orifice.

Challenging the evidence for pre-emptive coil embolisation of the internal iliac artery during endovascular aneurysm repair

OBJECTIVES

We retrospectively analysed the results of a strategy in which coverage of the internal iliac artery (IIA) during endovascular aneurysm repair (EVAR) was routinely performed without coil embolisation.

METHODS

From January 2010 until May 2012, 32 patients (96.9% men; mean age 73.0 years, range 52-89 years) underwent EVAR with stent grafts extended into the external iliac artery (EIA), all without prior coil embolisation. Aneurysm morphology was determined on preoperative computed tomography (CT) images. During follow-up, patients were interviewed about buttock claudication, and the occurrence of endoleaks and evolution of aneurysm diameter were recorded.

RESULTS

At baseline, the mid-common iliac artery (CIA) diameter was 33.5 ± 16.8 mm and seven patients presented with ruptured aneurysms. Mean follow-up was 14.3 ± 7.4 months. There were eight deaths, none related to IIA coverage. Buttock claudication occurred in seven (22.6%) patients, which persisted after 6 months in two cases of bilateral IIA coverage. No Type-I or -II endoleaks occurred related to IIA coverage. Aneurysm growth was not observed.

CONCLUSION

Endovascular treatment of aortoiliac and iliac aneurysm without pre-emptive coil embolisation of the IIA appears safe and effective. No IIA-related endoleaks or re-interventions occurred in our series. This approach saves operating time, contrast load and costs and may reduce complications. However, a larger population and longer follow-up is required to confirm our findings.

Type II endoleak after endovascular repair of abdominal aortic aneurysm: effectiveness of embolization

The purpose of this study was to report our experience in treating type II endoleaks after endovascular aneurysm repair (EVAR) of abdominal aortic aneurysms. Two hundred eighteen patients underwent EVAR with a Zenith stent-graft from January 2000 to December 2005. During a follow-up period of 4.5 + or - 2.3 years, solely type II endoleak was detected in 47 patients (22%), and 14 of them underwent secondary interventions to correct this condition. Ten patients had transarterial embolization, and four patients had translumbar/transabdominal embolization. The embolization materials used were coils, thrombin, gelatin, Onyx (ethylene-vinyl alcohol copolymer), and glue. Disappearance of the endoleak without enlargement of the aneurysm sac after the first secondary intervention was achieved in only five of these patients (5/13). One patient without surveillance imaging was excluded from analyses of clinical success. After additional interventions in four patients and the spontaneous disappearance of type II endoleak in two patients, overall clinical success was achieved in eight patients (8/12). One patient did not have surveillance imaging after the second secondary intervention. Clinical success after the first secondary intervention was achieved in two patients (2/9) in the transarterial embolization group and three patients (3/4) in the translumbar embolization group. The results of secondary interventions for type II endoleak are unsatisfactory. Although the small number of patients included in this study prevents reliable comparisons between groups, the results seem to favor direct translumbar embolization in comparison to transarterial embolization.

In vitro assessment of aortic stent-graft integrity following exposure to Onyx liquid embolic agent

PURPOSE

Endovascular stent-grafts are increasingly being used for treatment of abdominal and thoracic aortic aneurysms. Postprocedural complications include development of endoleaks. Recently, an embolic agent known as Onyx has been employed to treat type II endoleaks. Onyx is a biocompatible copolymer dissolved in dimethyl sulfoxide (DMSO). Although DMSO is known to damage some angiographic catheters, little is known concerning whether this compound damages stent-graft material. The current study was undertaken to directly explore this issue.

MATERIALS AND METHODS

Four stent-grafts were evaluated: the Excluder, Zenith, AneuRx, and Talent. Stent-grafts were incubated for 24 hours at 37 degrees C under each of the following conditions: DMSO alone, 50/50 mixture of DMSO/Onyx, mixture of 1 part 50/50 DMSO/Onyx and 9 parts whole blood, and untreated control. Stent-grafts were microdissected into 15-mm sections, after which they were evaluated with scanning electron microscopy.

RESULTS

No appreciable differences between stent-grafts exposed to DMSO and untreated controls were seen. Although liquid embolic agent was seen coating stent-grafts exposed to a 50/50 mixture of DMSO and Onyx, no evidence of fiber breakdown was noted. Stent-grafts exposed to DMSO/Onyx/whole blood demonstrated a thin coating of clot and Onyx without visual evidence of fiber compromise.

CONCLUSIONS

The current study provides compelling evidence that short-term exposure of endograft material to DMSO, DMSO/Onyx, or DMSO/Onyx/whole blood is not associated with acute structural compromise of four commonly used aortic endografts. Future in vivo studies will help to further establish the safety of this agent.

Percutaneous protective coil occlusion of the proximal inferior mesenteric artery before N-butyl cyanoacrylate embolization of type II endoleaks after endovascular repair of abdominal aortic aneurysms

Bowel ischemia can complicate treatment of type II endoleak with liquid or semiliquid agents such as n-butyl cyanoacrylate (NBCA) if nontarget embolization of the inferior mesenteric artery (IMA) occurs. The current report describes four cases of type II endoleak in which the IMA was the main outflow vessel and was prophylactically occluded with embolization coils before NBCA injection into the endoleak nidus. The purpose was to prevent unintentional embolization of the NBCA into IMA branches. If feasible, protective IMA coil occlusion should be considered in type II endoleaks with IMA outflow in cases of NBCA embolization.