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

Endovascular repair of abdominal aortic aneurysm-related type II endoleak: a multicenter study on the possibility of further intervention

Background

We aimed to analyze the risk factors associated with Type II endoleak (T2EL) requiring reintervention after endovascular aneurysm repair (EVAR) for multicenter abdominal aortic aneurysms.

Methods

A retrospective analysis was conducted on data from 614 patients with abdominal aortic aneurysms who underwent elective EVAR at three centers (Tianjin Medical University General Hospital, Affiliated Hospital of Inner Mongolia Medical University, Shanxi Provincial People's Hospital) from January 2017 to December 2021. After applying exclusion criteria, 375 patients were included in the study, with 50 patients in the T2EL-related reintervention group and 325 patients in the non-T2EL group. Single-factor and multiple-factor logistic analyses were used to identify high-risk factors, and ROC curve analysis was performed to determine the risk thresholds for mesenteric artery diameter, number of lumbar arteries, maximum aneurysm diameter, and proportion of intraluminal thrombus volume.

Results

The rate of T2EL-related reintervention among the 375 patients was 13.33% (50/375). Single-factor analysis indicated that age, hypertension, maximum aneurysm diameter, proportion of intraluminal thrombus, diameter of inferior mesenteric artery (IMA), and number of patent lumbar arteries (LA) were risk factors for T2EL-related reintervention. Multiple-factor logistic analysis identified maximum aneurysm diameter, proportion of thrombus, IMA diameter, and number of patent LA as the main influencing factors for T2EL-related reintervention after EVAR. Significant risk factors for reintervention were maximum aneurysm diameter (OR = 1.043, 95% CI 1.015-1.072, P = 0.002), IMA diameter (OR = 3.901, 95% CI 1.116-13.632, P = 0.033), and number of LA (OR = 2.584, 95% CI 1.722-3.769, P < 0.001). A significant protective factor for reintervention was thrombus proportion (OR = 0.895, 95% CI 0.864-0.927, P < 0.001). ROC curve analysis showed that the risk thresholds for reintervention were an IMA diameter of 2.95 mm, intraluminal thrombus volume proportion <42.5%, number of LA ≤5.5, and aneurysm diameter of 53.55 mm.

Conclusion

Cases with identified risk factors are considered to have a higher risk of T2EL-related reintervention after EVAR. Exceeding the new risk thresholds may indicate a higher likelihood of T2EL-related reintervention after EVAR.

Spontaneous Inferior Mesenteric Artery Occlusion after Endovascular Aneurysm Repair for Abdominal Aortic Aneurysm and its Impact on Clinical Outcomes

OBJECTIVE

The incidence and related factors of spontaneous occlusion of a patent inferior mesenteric artery (IMA) after endovascular aneurysm repair (EVAR) for abdominal aortic aneurysm (AAA) without pre-emptive embolisation remain unclear. This study aimed to elucidate the incidence, clinical implications, and predictors of spontaneous IMA occlusion after EVAR.

METHODS

This was a single centre, retrospective cohort study. Patients who underwent elective EVAR between 2007 and 2022 were categorised into three groups (group 1, spontaneous IMA occlusion; group 2, patent IMA with no type II endoleak [T2EL] from IMA; group 3, T2EL from IMA). Endpoints were the incidence of spontaneous IMA occlusion, sac enlargement, freedom from re-intervention, and overall survival after EVAR.

RESULTS

Of 372 cases of elective EVAR for AAA, 230 who had patent IMA pre-operatively were analysed, after excluding 127 with pre-occluded IMA and 15 who underwent pre-emptive IMA embolisation. Spontaneous IMA occlusion occurred in 101 patients (43.9%). The sac enlargement rate was lower in group 1 than in groups 2 and 3. The freedom from re-intervention rate was higher in group 1 than in group 3 but did not differ between groups 1 and 2. Multivariable analysis revealed the absence of antiplatelet therapy, pre-operative higher haematocrit, absence of concomitant iliac artery aneurysm, posterior thrombus in the sac, and use of Endurant as predictors associated with spontaneous IMA occlusion. Spontaneous IMA occlusion was observed in 7.1% and 77.5% of patients with zero and four or five predictors, respectively.

CONCLUSION

Spontaneous IMA occlusion occurred in nearly half of cases and was associated with positive clinical outcomes. In patients with a high prediction of spontaneous IMA occlusion, pre-emptive IMA embolisation may be omitted.

Preemptive Embolization of Abdominal Aortic Aneurysm Sac Side Branch Arteries Promotes Early Sac Shrinkage after Endovascular Aneurysm Repair 1

BACKGROUND

The association between the occlusion rate of the side branch arteries branching from the abdominal aortic aneurysm sac and aneurysm sac shrinkage is unclear. We aimed to evaluate the efficacy of preemptive embolization of multiple side branch arteries branching from the abdominal aortic aneurysm sac in early aneurysm sac shrinkage after endovascular aneurysm repair.

METHODS

Patients undergoing endovascular aneurysm repair of abdominal aortic aneurysms, with or without preemptive embolization of multiple side branch arteries, including the inferior mesenteric artery and lumbar arteries, between January 2016 and August 2021, were retrospectively evaluated. Preemptive embolization was introduced at our institution in January 2018 and has been performed in all patients who undergo endovascular aneurysm repair since then. We compared occlusion rates of the side branch arteries, frequency of type 2 endoleaks, changes in aneurysm sac size, percentage of aneurysm sac size decrease, and frequency of reduction in the aneurysm sac diameter by > 5 mm.

RESULTS

The study included 43 patients in the embolization group and 20 in the nonembolization group. Preemptive embolization was successfully performed without any ischemic complications. The total occlusion rate of side branch arteries was significantly higher in the embolization group than in the nonembolization group (70.2% vs. 29.3%, P < 0.05). At 24 months of follow-up, the type 2 endoleak frequency was significantly lower in the embolization group than in the nonembolization group (6.9% vs. 31.6%, P < 0.05). The frequency of reduction in the aneurysm sac diameter by > 5 mm was significantly higher in the embolization group than in the nonembolization group at 24 months (62.1% vs. 31.6% P < 0.05). The optimal cutoff value for the total occlusion rate of the side branch arteries to achieve reduction in the aneurysm sac diameter by > 5 mm at 24 months, after endovascular aneurysm repair, was 66.7% in all patients (area under the curve = 0.634; sensitivity = 62.5%; specificity = 70.8%). These findings suggest that occluding 66.7% or more of the side branch arteries may result in early aneurysmal shrinkage.

CONCLUSIONS

Preemptive embolization of multiple side branch arteries, branching from the abdominal aortic aneurysm sac, may contribute to early aneurysm sac shrinkage; this may serve as a marker for fewer late complications after endovascular aneurysm repair.

An Expert-Based Review on the Relevance and Management of Type 2 Endoleaks Following Endovascular Repair of Ruptured Abdominal Aortic Aneurysms

Ruptured abdominal aortic aneurysms (rAAAs) are life-threatening and require emergent surgical therapy. Endovascular aortic repair for rupture (rEVAR) has become the leading strategy due to its minimal invasive approach with expected lower morbidity and mortality, especially in patients presenting with hemodynamic instability and relevant comorbidities. Following rEVAR, intraoperative angiography or early postinterventional computed tomography angiography have to exclude early type 1 or 3 endoleaks requiring immediate reintervention. Persistent type 2 endoleaks (T2ELs) after rEVAR, in contrast to elective cases, can cause possibly lethal situations due to continuing extravascular blood loss through the remaining aortic aneurysm rupture site. Therefore, early identification of relevant persistent T2ELs associated with continuous bleeding and hemodynamic instability and immediate management is mandatory in the acute postoperative setting following rEVAR. Different techniques and concepts for the occlusion of T2ELs after rEVAR are available, and most of them are also used for relevant T2ELs after elective EVAR. In addition to various interventional embolization procedures for persistent T2ELs, some patients require open surgical occlusion of T2EL-feeding arteries, abdominal compartment decompression or direct surgical patch occlusion of the aneurysm rupture site after rEVAR. So far, in the acute situation of rAAAs, indications for preemptive or intraoperative T2EL embolization during rEVAR have not been established. In the long term, persistent T2ELs after rEVAR can lead to continuous aneurysm expansion with the possible development of secondary proximal type I endoleaks and an increased risk of re-rupture requiring regular follow-up and early consideration for reintervention. To date, only very few studies have investigated T2ELs after rEVAR or compared outcomes with those from elective EVAR regarding the special aspects of persisting T2ELs. This narrative review is intended to present the current knowledge on the incidence, natural history, relevance and strategies for T2EL management after rEVAR.

Preemptive Embolization of the Lumbar Arteries and Inferior Mesenteric Artery to Prevent Abdominal Aortic Aneurysm Enlargement Associated with Type 2 Endoleak Following Endovascular Aneurysm Repair

Purpose

This study aims to evaluate the efficacy of preemptive embolization (PE) of the lumbar arteries (LAs) and inferior mesenteric artery (IMA) (PELI) for preventing abdominal aortic aneurysm (AAA) enlargement associated with type 2 endoleak (T2EL).

Material and Methods

Patients who underwent endovascular aneurysm repair (EVAR) between January 2015 and December 2020 were classified into the control (without PE), IMA (PE of a patent IMA with a diameter ≥2.5 mm), and PELI (PE of patent LAs with a diameter ≥2 mm and IMA) groups. The rate of freedom from AAA enlargement following EVAR (enlargement ≥5 mm from pre-EVAR) was compared using the log-rank test. The prevalence of T2EL at 6 months and 1 year after EVAR was compared using Fisher's exact test.

Results

The cumulative rates of freedom from AAA enlargement at 54 months after EVAR (maximum observational period in the PELI group) were as follows: control group, 77.5%; IMA group, 62.5%; and PELI group, 100%. The mean CT follow-up periods of the control, IMA, and PELI groups were 46.4 ± 22.3, 31.1 ± 20.6, and 22.9 ± 15.5 months, respectively. None of the 31 patients in the PELI group experienced AAA enlargement after EVAR, whereas 2 out of the 16 patients in the IMA group and 20 out of the 98 patients in the control group had AAA enlargement. No significant differences were observed in the rate of freedom from AAA enlargement (PELI group vs. IMA group, P = 0.11; PELI group vs. control group, P = 0.11). The prevalence of T2EL was significantly lower in the PELI group than in the control group at 6 months (13.6% in PELI group vs. 42.1% in control group, P = 0.02) and 1 year (14.3% in PELI group vs. 40.0% in control group, P = 0.04).

Conclusions

PELI was significantly associated with a low prevalence of T2EL and may prevent T2EL-associated AAA enlargement.

A nomogram risk assessment model to predict the possibility of type II endoleak-related re-intervention after endovascular aneurysm repair (EVAR)

This study aimed to develop and validate a novel nomogram risk assessment model to predict the possibility of type II endoleak (T2EL)-related re-intervention. The data of 455 patients with abdominal aortic aneurysms who underwent elective endovascular aneurysm repair (EVAR) procedures between January 2018 and December 2021 at our single center were retrospectively reviewed. Following the implementation of exclusion criteria, 283 patients were finally included and divided into T2EL-related re-intervention (n = 42) and non-T2EL (n = 241) groups. The overall T2EL-related re-intervention rate for 283 patients was 14.8% (42/283). Using multivariate analysis, significant risk factors for re-intervention included age (OR, 1.172; 95% CI, 1.051-1.307; P = 0.004), smoking (OR, 13.418; 95% CI, 2.362-76.215; P = 0.003), diameter of inferior mesenteric artery (IMA) (OR, 21.380; 95% CI, 3.060-149.390; P = 0.002), and number of patent lumbar arteries (OR, 9.736; 95% CI, 3.175-29.857; P < 0.001). The discrimination ability of this risk-predictive model was reasonable (concordance index [C-index] = 0.921; 95% CI, 0.878-0.964). The Hosmer-Lemeshow goodness of fit test was performed on the model, and the chi-square value was 3.210 (P = 0.920), presenting an excellent agreement between the model-predicted and observed values. The receiver operating characteristic (ROC) curve identified that the risk thresholds of re-intervention were a diameter of > 2.77 mm for the diameter of the inferior mesenteric artery and a proportion of < 45.5% for thrombus volume in the aneurysm sac. This novel nomogram risk assessment model for predicting the possibility of patients' T2EL-related re-interventions after EVAR should be helpful in discriminating high-risk patients. Two novel risk thresholds may imply a higher possibility of T2EL-related re-intervention after EVAR.

Preoperative predictive factors for type II endoleak: Trying to define high-risk patients

OBJECTIVE

Type 2 endoleaks (T2E) continue to be the "Achilles Heel" of endovascular aneurysm repair (EVAR). The aim of this study is to analyze preoperative factors of patients who underwent EVAR to define risk factors for T2E.

METHODS

From January 2015 to June 2020, 140 of 191 patients who underwent EVAR in our institution meet inclusion criteria for this study. Postoperative image control were performed using duplex ultrasound or CT scan. All T2E detected during follow-up were confirmed by angio CT. Preoperative anatomic and clinical variables were analyzed for T2E using t-test, Mann-Whitney U test and Fisher exact test. ROC curves and the corresponding area under the curve (AUC) were used to describe the predictive accuracy for endoleak.

RESULTS

T2E was detected in 16 patients (11.43%)0.12 of them (75%) were persistent and 10 (62.5%) provoked sac enlargement. Predictive factors for T2E were a greater IMA diameter (2.5 ± 0.5 vs. 3.3 ± 0.5, p < 0.001) and an increasing number of LA (4.8 ± 1.6 vs. 6.7 ± 1.4, p < 0.001). ROC curve analysis stablished thresholds of 3.5 mm for IMA diameter (sensitivity 77%, specificity 86%) and 5.5 for patent LA (sensitivity 88%, specificity 59%) as risk factor to develop T2E.

CONCLUSIONS

Preoperative aortic side branches embolization to avoid T2E is not still standarised. We tried to define a group of high-risk patients for T2E. According to our findings, patients with a preoperative IMA> 3 mm and more than 5 patent LA should be considered for pre-EVAR embolization.

Inferior Mesenteric Artery Associated Type II Endoleaks: Are They Predictable?

Purpose: This study aims to evaluate the relationship between inferior mesenteric artery (IMA) diameter and risk of type II endoleak.

Subjects and Methods: A retrospective study design to review all EVARs performed over a 4-year period at a tertiary care center. Out of the total cohort of 400 patients who underwent EVAR, 41 patients (10.3%) developed type II endoleak. The mean IMA ostial diameter for patients with type II endoleak secondary to IMA contributories was 4mm, while the mean IMA diameter for patients with lumbar arteries contributing to the type II endoleak was 3.7mm.

Results: Statistical analysis using a paired t-test did not show a statistically significant difference in the IMA ostial diameter between the two groups.

Conclusion: There is no significant correlation between preprocedural IMA ostium diameter and type II endoleak development and hence, preprocedural IMA embolization is not an appropriate prophylactic management strategy.

Midterm Outcomes of Endovascular Abdominal Aortic Aneurysm Repair with Prevention of type 2 Endoleak by Intraoperative Aortic Side Branch Coil Embolization

OBJECTIVE

The midterm results of endovascular abdominal aortic aneurysm repair (EVAR) with aortic side branch coil embolization during EVAR was evaluated.

METHODS

Our center began coil embolization for all patent inferior mesenteric artery (IMA) and lumbar artery (LA) with an inner diameter more than 2.0 mm during EVAR since June 2015. When four or more LA were patent, coil embolization for LA with inner diameter 2.0 mm or less was done. EVAR without aortic side branches coil embolization was performed for 59 patients prior to June 2015 (control group) and 79 patients underwent EVAR with coil embolization during EVAR (coil group). The success rate of coil embolization for IMA and LA was evaluated in coil group. The frequency of type 2 endoleak (T2EL), freedom from aneurysm sac expansion (5 mm or more) rate and the rate of the aneurysm sac shrinkage (10 mm or more) were compared between the coil and control groups. Additionally, multiple logistic regression analysis for all patients was conducted to analyze whether IMA patency and the number of patent lumbar artery at the end of EVAR were the risk factors of the aneurysm sac expansion of 5 mm or more.

RESULTS

The success rate of IMA coil embolization was 96.4% and that of LA was 74.5%. Compared to the control group, the frequency of T2EL was significantly lower in coil group at 7 days (1.3% vs. 60.4%, P <0.0001) and at 6 months (2.1% vs 38.2%, P <0.0001) after EVAR. The freedom from aneurysm sac expansion rate was significantly better in the coil group at 5 years (100% in coil group and 65.2% in control group, P = 0.002). The rate of aneurysm sac shrinkage was significantly better in coil group (15.5% vs. 2.0% at 1 year, 42.8% vs. 6.3% at 2 years and 53.4% vs. 17.8% at 3 years, p = 0.0007). The risk of aneurysm sac expansion of 5 mm or more was estimated to be 11 times greater when the IMA was patent, and 4.9 times greater when 3 or more LAs were patent at the end of EVAR.

CONCLUSION

When IMA was occluded and the number of patent LA became 2 or less by aortic side branch coil embolization during EVAR, favorable mid-term results were safely obtained and good long-term result could be expected with EVAR.

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.

Embolization of Type 2 Endoleaks in the Abdominal Aorta Using Ethylene Vinyl Alcohol Copolymer

BACKGROUND

 Type 2 endoleaks (T2EL) are the most frequent complication following endovascular aortic repair. Multiple studies primarily deal with the technical and clinical success of the embolization of persisting T2EL, thereby revealing controversial outcomes. Current reports rarely focus on the detailed execution of such a complex interventional procedure with respect to the difficult anatomic setting.

METHODS

 The present review provides an in-depth depiction and evaluation of the interventional methodology of the embolization of T2EL in the abdominal aorta with use of ethylene vinyl alcohol copolymer (EVOH). Complicating anatomic conditions are taken into account as well as technical and clinical success rates.

RESULTS

 Using the transarterial approach, there are at least 4 different pathways to access the nidus of a T2EL. CT-guided direct puncture of the aneurysm sac provides an alternative method of high technical success. EVOH with its slow solidification characteristics enables good control to achieve complete filling of the T2EL. During the intervention, however, it remains difficult to meet exactly the embolization endpoint, especially in large T2ELs.

CONCLUSION

 T2EL embolization using EVOH is an effective treatment with low major complication rates when conducted by skilled interventionists with detailed knowledge of diverse complex access routes.

KEY POINTS

  · Many roads lead to Rome to access the nidus of a T2EL including diverse complex transarterial pathways and direct aneurysm sac puncture.. · Ethylene vinyl alcohol co-polymer enables good control for slow filling of the nidus with low risk of major complications.. · Identification of the embolization endpoint remains difficult during the procedure and may result in secondary interventions.. · Successful T2EL embolization requires detailed knowledge of all access routes to the nidus and skilled handling of liquid embolics..

CITATION FORMAT

· Nolte-Ernsting C, Mecklenbeck F, Stehr A. Embolization of Type 2 Endoleaks in the Abdominal Aorta Using Ethylene Vinyl Alcohol Copolymer. Fortschr Röntgenstr 2021; DOI: 10.1055/a-1502-7883.

Predictive Factors and Strategies to Prevent the Development of Type 2 Endoleaks following Endovascular Aneurysm Repair

Type 2 endoleaks are a potential complication of endovascular aortic repair for abdominal aortic aneurysms. They are caused by vessels that have been excluded from the aorta lumen, but may still fill the aneurysm sac due to collateral filling. Type 2 endoleaks may lead to increased morbidity and need for additional procedures. Being able to identify patients at risk for Type 2 endoleaks and prevent them is important for any physician who is performing endovascular aortic repair.

Predictive Factor of the Possibility for Aortic Side Branches Coil Embolization during Endovascular Abdominal Aortic Aneurysm Repair

Objective: Coil embolization of aortic side branches has been additionally performed to prevent type II endoleak during EVAR in our institute. In this study, we evaluated the predictive factors of the possibility for coil embolization of the inferior mesenteric artery (IMA) and lumbar artery (LA) during EVAR.

Methods: Seventy-four EVAR patients during June 2015 and April 2019 were included in the study. The coil embolization procedural time for one vessel is limited to 10 min. Aortic side branches were selected with 4 Fr Shepherd hook type catheter (Medikit, Tokyo, Japan) and were embolized with Interlock (Boston Scientific, MA, USA) via microcatheter. As predictive factors, internal diameter of aortic side branches and the aortic diameter perpendicular to the origin of LA (aortic diameter) were evaluated.

Results: Coil embolization was tried for 52 patent IMAs and all IMAs except two IMAs with ostial stenosis were successfully coil embolized (96.2%). Totally 190 LAs were patent and coil embolization was tried for 144 LAs. Among 144 LAs, 106 LAs (73.6%) were successfully coil embolized and the diameter was significantly longer (2.30±0.51 mm vs. 2.04±0.41 mm, p=0.007) and aortic dimeter was significantly shorter (30.0±8.1 mm vs. 40.5±11.6 mm, p<0.001) in successfully embolized LAs. Cut off value of successful LA coil embolization was 2.06 mm for internal diameter and 36.1 mm for aortic diameter by receiver operating characteristic curve analysis. Successful coil embolization rate for LAs with internal diameter longer than 2.0 mm and aortic diameter less than 36.2 mm was 90% (72 among 80 LAs).

Conclusion: Coil embolization during EVAR for IMA was highly successful, if there was no calcified ostial stenosis. LA embolization was feasible especially for LAs with internal diameter ≥2.0 mm and aortic diameter ≤36.1 mm. This information would be useful to select the target vessel for aortic side branches coil embolization during EVAR. (This is a translation of Jpn J Vasc Surg 2019; 28: 389–396.)

Multicentre randomised controlled trial to evaluate the efficacy of pre-emptive inferior mesenteric artery embolisation during endovascular aortic aneurysm repair on aneurysm sac change: protocol of Clarify IMA study

INTRODUCTION

Type II endoleak (EL) is frequently seen after endovascular aneurysm repair (EVAR) for abdominal aortic aneurysm (AAA) and is often considered responsible for aneurysm sac enlargement if it persists. In order to reduce type II EL and consequent sac enlargement, pre-emptive embolisation of the inferior mesenteric artery (IMA), which is a main source for persistent type II EL, has been introduced in many vascular centres. At present, there is a lack of robust evidence to support the efficacy of pre-emptive embolisation of IMA on reduction of persistent type II EL with subsequent sac shrinkage.

METHOD AND ANALYSIS

This multicentre, randomised controlled trial will recruit 200 patients who have fusiform AAA ≥50 mm/rapidly enlarging fusiform AAA, with patent IMA, and randomly allocate them either to a pre-emptive IMA embolisation group or non-embolisation control group in a ratio of 1:1. The primary endpoint is the difference of aneurysm sac volume change assessed by CT scans between the pre-emptive IMA embolisation group and the control group at 12 months after EVAR. The secondary endpoints are defined as change of aneurysm sac volume in both groups at 6 and 24 months, freedom from sac enlargement at 12 and 24 months after EVAR, prevalence of type II EL at 1, 6, 12 and 24 months evaluated by contrast-enhanced CT, reintervention rate, aneurysm related mortality, overall survival, perioperative morbidity, volume of contrast media used during EVAR and dosage of radiation.

ETHICS AND DISSEMINATION

The protocol has been reviewed and approved by the ethics committee of Nara Medical University (No. 2113). The findings of this study will be communicated to healthcare professionals, participants and the public through peer-reviewed publications, scientific conferences and the University Hospital Medical Information Network Clinical Trials Registry home page.

TRIAL REGISTRATION NUMBER

UMIN000035502.

Preoperative Inferior Mesenteric Artery Embolization is a Cost-effective Technique that May Reduce the Rate of Aneurysm Sac Diameter Enlargement and Reintervention After EVAR

BACKGROUND

Type II endoleaks are the most common complications after endovascular repair of abdominal aortic aneurysms (EVARs). Some studies have shown the benefit of preventive inferior mesenteric artery (IMA) embolization, but its efficacy and cost-effectiveness continue to be controversial. The aim of this study was to evaluate the efficacy of this procedure on the increase in aneurysmal sac diameter during follow-up.

MATERIALS AND METHODS

All consecutive patients who underwent the embolization of the IMA before EVAR in our center, between January 2014 and July 2016, were included. We retrospectively compared the diameter of the aortic aneurysm sac, the rate of endoleak and reinterventions, and the theoretical cost of management between these patients (group 2) and a historical cohort of patients treated for EVAR before January 2014 who did not undergo prior IMA embolization (group 1).

RESULTS

Two hundred twenty-four patients were retrospectively analyzed. After exclusion, we compared a group of 37 embolized patients with a control group of 46 patients. The rate of enlargement in the aneurysmal sac diameter was significantly higher in the control group at 2 years (27.9% vs. 4.3%, P = 0.025). The type II endoleak rate at 2 years was significantly higher in the control group (53.1% vs. 18.2%, P = 0.012), as was the aneurysm-related reintervention rate (31.1% vs. 8.1%, P = 0.013). Multivariate analysis confirmed these results. At 2 years of follow-up, there was no difference in the overall cost of patient management between the 2 groups.

CONCLUSIONS

Preventive IMA embolization is an effective, reliable, and cost-effective technique that seems to reduce the rate of the aneurysmal sac diameter enlargement, type II endoleak, and reinterventions after EVAR.

Pre-operative Aneurysm Thrombus Volume, But Not Density, Predicts Type 2 Endoleak Rate Following Endovascular Aneurysm Repair

BACKGROUND

The impact of aneurysm thrombus characteristics on type 2 endoleak rate following endovascular aneurysm repair (EVAR) for abdominal aortic aneurysm (AAA) is unclear. The purpose of this study is to determine the impact of pre-operative aneurysm thrombus volume and density on the incidence of type 2 endoleak following EVAR for infrarenal AAA.

METHODS

A retrospective analysis was completed on all patients who underwent standard EVAR at an academic medical institution between May 1, 2010 and June 1, 2016 with a minimum follow-up period of 12 months. The final analysis included 170 patients. Thrombus volume and density were determined by analyzing pre-operative computed tomography angiography (CTA) scans using the TeraRecon plaque analysis module. The number and diameter of patent infrarenal aortic branch vessels were also identified. Type 2 endoleak was diagnosed by post-operative CTA, duplex ultrasound, or angiography.

RESULTS

Over a median follow-up period of 29 months, 88 (51.8%) of 170 patients had a type 2 endoleak. The thrombus volume as a proportion of the infrarenal aorta volume was significantly lower in patients with type 2 endoleak (odds ratio [OR] 0.034, 95% confidence interval [CI] 0.005-0.291, P = 0.002). The number of patent lumbar arteries was significantly greater in patients with type 2 endoleak (OR 1.45, 95% CI 1.16-1.56, P < 0.0005). Both variables independently predicted the incidence of type 2 endoleak in a multivariate analysis. Thrombus density was not related to the incidence of type 2 endoleak.

CONCLUSIONS

A lower ratio of thrombus volume/infrarenal aorta volume and a higher number of patent lumbar arteries were associated with an increased incidence of type 2 endoleak. A multivariate logistic regression model was generated to pre-operatively predict the risk of type 2 endoleak. This model can guide the stratification of patients for intensity of endoleak surveillance following EVAR and consideration of pre-operative treatment.

Selective Inferior Mesenteric Artery Embolization during Endovascular Abdominal Aortic Aneurysm Repair to Prevent Type II Endoleak

PURPOSE

The purpose of this study was to evaluate the efficacy of simultaneous IMA (s-IMA) embolization during the endovascular abdominal aortic aneurysm repair (EVAR).

MATERIALS AND METHOD

From July 2007 to January 2011, 189 patients in the no embolization (NE) group underwent EVAR without the indication for s-IMA embolization. Since February 2011 to April 2014, 143 patients have undergone EVAR. Among these patients, 26 patients underwent s-IMA embolism under a predefined indication and constituted the simultaneous embolization (SE) group. The indications for s-IMA embolization were defined by preoperative computed tomography (CT) findings, as follows: (1) the diameter was greater than 2.5 mm and (2) no stenosis due to thrombus or calcification at its orifice.

RESULTS

The incidence of a type II endoleak from the IMA was 3.4% (5/143) in the SE group patients and 13.2% (25/189) in the NE group patients (p = 0.013), and the incidence of a type II endoleak from all branches (i.e., IMA, lumbar, medial sacral arteries) was 15.4% (22/143) in the SE group patients and 32.3% (61/189) in the NE group patients (p = 0.0003). During the follow-up period (range, 6-72 months; mean: 28 months), the reintervention rate for a type II endoleak from the IMA and/or other branches was 9.5% (18/189) in the NE group and 0.6% (1/143) in the SE group (p = 0.0001).

CONCLUSION

In selected patients, performing an s-IMA embolization, based on CT findings, decreased the incidence of a type II endoleak and reintervention from the IMA and from all branches.

The Influence of 4 or more Patent Lumbar Arteries on Persistent Type II Endoleak and Sac Expansion after Endovascular Aneurysm Repair

BACKGROUND

This study aimed to review our clinical results and determine how preoperative patent lumbar arteries (LAs) influence the occurrence of type II endoleaks or aneurysm sac enlargement after endovascular aneurysm repair (EVAR) and to identify the preoperative computed tomography findings of persistent type II endoleaks from patent LAs that indicate the need for preventive procedures during EVAR.

METHODS

A total of 293 patients who underwent EVAR for infrarenal abdominal aortic aneurysm (AAA) between August 2007 and July 2013 were reviewed. Follow-up data were available for 194 patients (76% male, mean age 78 ± 6.8 years), and the mean follow-up time was 57 ± 23 months.

RESULTS

The number of patent LAs was identified as a significant positive predictor of persistent type II endoleaks (hazard ratio [HR], 1.4; 95% confidence interval [CI]: 1.2-1.7; P < 0.001) and sac enlargement (≥5 mm) at the 2-year follow-up period (HR, 1.3; 95% CI: 1.1-1.8; P = 0.009) after EVAR, using Cox regression analysis. The receiver operating characteristics curve (AUC: 0.72) showed that a cutoff of 4 patent LAs resulted in a sensitivity of 87% and specificity of 48%. The rates of freedom from sac enlargement (≥5 mm) at 3 and 5 years after EVAR were significantly lower in patients with 4 or more patent LAs than in those with fewer (90% and 76% vs. 96% and 89%; P = 0.0008).

CONCLUSIONS

The number of patent LAs is associated as a significant risk factor with the development of persistent type II endoleaks and sac enlargement after EVAR. Four or more patent LAs should be recognized as the group having an elevated risk of developing late sac enlargement after EVAR.

Preoperative risk factors for aneurysm sac expansion caused by type 2 endoleak after endovascular aneurysm repair

Purpose

The objective of this study was to investigate the preoperatively definable risk factors which predict the aneurysm sac expansion caused by persistent type 2 endoleak after endovascular aneurysm repair.

Methods

Between 2008 and 2014, retrospective analysis was performed to examine the predictive risk factors for aneurysm sac enlargement caused by persistent type 2 endoleak, which was defined as a continuous endoleak present for more than six months. Aneurysm sac expansion was diagnosed if the maximum transverse diameter increased by 5 mm or more compared with the preoperative measurement.

Results

During the study period, endovascular aneurysm repair was performed in 211 patients with abdominal aortic aneurysm and common iliac artery aneurysm. Sac enlargement for type 2 endoleaks was observed in 20 patients (9.5%). The presence of more than five patent lumbar arteries flowing into aneurysm sac in the preoperative computed tomography (hazard ratio, 3.37; 95% confidence interval, 1.24–10.8; p = 0.017) was a predictive factor for sac expansion caused by persistent type 2 endoleak on Cox regression analysis. The presence of a patent inferior mesenteric artery was not associated with the sac expansion caused by persistent type 2 endoleak.

Conclusions

The presence of more than five lumbar arteries flowing into the aneurysm sac was a preoperative risk factor for sac expansion caused by persistent type 2 endoleak.

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.

Predictive Factors for the Development of Type 2 Endoleak Following Endovascular Aneurysm Repair

Type 2 endoleak (T2EL) is the most common complication following endovascular aneurysm repair (EVAR) for abdominal aortic aneurysms. The management of T2ELs is controversial due to the relatively low incidence of negative outcomes when secondary intervention is avoided. Some studies challenge this practice as demonstrated by adverse events following conservative treatment of T2ELs. Evidence has shown that the preoperative computed tomographic angiogram can predict the development of T2EL based on a patient's arterial anatomy, specifically vessels associated with increased rates of post-EVAR endoleak development. Preoperative embolization of those aortic branch vessels associated with T2ELs has shown decreased rates of postoperative complications and may result in a decreased need for surveillance and reintervention.

Is Inferior Mesenteric Artery Embolization Indicated Prior to Endovascular Repair of Abdominal Aortic Aneurysm?

Type II endoleak is a common condition occurring after endovascular repair of abdominal aortic aneurysms (EVAR), and may result in aneurysm sac growth and/or rupture in a small number of patients. A prophylactic strategy of inferior mesenteric artery (IMA) embolization before EVAR has been advocated, however, the benefits of this strategy are controversial. A clinical vignette allows the authors to summarize the available data about this issue and discuss the possible benefits and risks of prophylactic IMA embolization before EVAR. The authors performed a meta-analysis of available data which showed that the pooled rate of type II endoleak after IMA embolization was 19.9% (95% CI 3.4-34.7%, I2 93%) whereas it was 41.4% (95% CI 30.4-52.3%, I2 76%) in patients without IMA embolization (5 studies including 596 patients: p < .0001, OR 0.369, 95% CI 0.22-0.61, I2 27%). Since treatment for type II endoleaks is needed in less than 20% of cases and this complication can be treated successfully in 60-70% of cases resulting in an aneurysm rupture risk of 0.9%, these data indicate that embolization of patent IMA may be of no benefit in patients undergoing EVAR.

Complexity of persistent type II endoleak associated with sac expansion after endovascular abdominal aortic aneurysm repair

Type II endoleak after endovascular aortic aneurysm repair still remains the Achilles' heel of the treatment, the source of which regularly is difficult to identify and treat. We present a patient with a persistent type II endoleak associated with a continuous aneurysm sac expansion after endovascular aortic aneurysm repair for which many diagnostic modalities were used during his follow-up such as duplex scan, computed tomography angiography and magnetic resonance angiography. Attempts were undertaken to treat the source of endoleak including coil micro-embolisation of lumbar arteries and subsequent open ligation of the inferior mesenteric artery, but they failed to eliminate the endoleak. Finally, a middle sacral artery was identified as the source of the endoleak. At that time, the patient was subjected to surgery for sigmoid carcinoma, and simultaneously, a ligation of the sacral artery was undertaken which eventually eliminated the endoleak completely. This case highlights that type II endoleak may be evoked by various sources and there can be a great difficulty to identify these feeding vessels; thus, careful planning for its management is mandatory.