Sac enlargement without endoleak: When and how to convert and technical considerations

CIRSE Standards of Practice on Management of Endoleaks Following Endovascular Aneurysm Repair

BACKGROUND

Endoleaks represent the most common complication after EVAR. Some types are associated with ongoing risk of aneurysm rupture and necessitate long-term surveillance and secondary interventions.

PURPOSE

This document, as with all CIRSE Standards of Practice documents, will recommend a reasonable approach to best practices of managing endoleaks. This will include imaging diagnosis, surveillance, indications for intervention, endovascular treatments and their outcomes. Our purpose is to provide recommendations based on up-to-date evidence, updating the guidelines previously published on this topic in 2013.

METHODS

The writing group was established by the CIRSE Standards of Practice Committee and consisted of clinicians with internationally recognised expertise in endoleak management. The writing group reviewed the existing literature performing a pragmatic evidence search using PubMed to select publications in English and relating to human subjects up to 2023. The final recommendations were formulated through consensus.

RESULTS

Endoleaks may compromise durability of the aortic repair, and long-term imaging surveillance is necessary for early detection and correct classification to guide potential re-intervention. The majority of endoleaks that require treatment can be managed using endovascular techniques. This Standards of Practice document provides up-to-date recommendations for the safe management of endoleaks.

Enlarging aneurysm sac post EVAR - type V or occult type II Endoleak?

PURPOSE

Several theories exist regarding the underlying mechanism of type V endoleaks (T5EL), which remains unclear. Torikai et al. (2018) describe sac expansion in cases with patchy heterogenous enhancement of peripheral thrombus and postulate these are due to atypical type II endoleaks (T2EL) from proliferated vasa vasora. These cases of apparent endotension pose a therapeutic challenge as continued sac expansion warrants active intervention.

MATERIALS AND METHODS

Retrospective review of T5EL cases was performed who underwent multidisciplinary discussion at our institution between 2020-2021. Clinical history and imaging were reviewed by a vascular interventional radiologist aiming to identify the underlying mechanism of sac expansion.

RESULTS

Two cases of these specific T5ELs were identified. One patient underwent endovascular management and image-guided aspiration of intra-sac fluid whilst another underwent open surgical ligation and sac plication. In both cases, fluid re-accumulated with re-expansion of the aneurysmal sac on follow-up. Careful review of CT imaging showed subtle foci of peripheral sac enhancement, suggestive of vasa vasora causing occult T2ELs. This was not visible on single phase CTA, super-selective angiography or cone beam CT.

CONCLUSION

We identified two complex cases with unexplained sac expansion following EVAR suggestive of T2ELs from proliferated vasa vasora. Transcatheter embolisation of this network of vessels although challenging has been previously considered to stunt sac expansion. We suggest this phenomenon is under-diagnosed. Nevertheless, long-term surveillance is warranted as continued sac expansion risks changes in aneurysm morphology leading to potential loss of the proximal/distal seal zones.

Platelet Count Recovery after Endovascular Aneurysm Repair for Abdominal Aortic Aneurysm

Objective: To find a new predictor of endoleak (EL) and aneurysm sac expansion after endovascular aneurysm repair (EVAR), we evaluated the platelet count recovery (PCR) process after EVAR.

Materials and Methods: Two hundred five patients treated with elective EVAR from 2007 to 2015 were retrospectively analyzed. We compared the platelet count ratio until postoperative day (POD) 7 to the presurgical baseline between patients with and without persistent EL (≥ 6 months). Subsequently, we calculated the optimal platelet count ratio for distinguishing persistent EL using receiver-operating characteristics analysis. A platelet count ratio on POD7 ≥118% was defined as the PCR. We evaluated the PCR’s influence on the cumulative aneurysm sac expansion rate.

Results: The average platelet count ratio on POD7 rose above baseline (112%), and the ratio was attenuated by persistent EL (103%). Of 205 patients, 126 (61%) were assigned to the disturbed PCR group (PCR(−) group). Cumulative aneurysm sac expansion rate was higher in the PCR(−) group than the PCR(+) group (34.4% vs. 12.8% in 5 years, p=0.01).

Conclusion: Disturbed PCR after EVAR may be associated with ELs and eventual aneurysm sac expansion.

Stent-Graft Relining by Combined Aortic Cuff with Double-D Technique for Type IIIb or V Endoleak after Endovascular Aneurysm Repair: A Case Report

We report the case of a 83-year-old man with aneurysmal sac enlargement after endovascular aneurysm repair for an abdominal aortic aneurysm, despite no overt endoleak (EL) detected on imaging. Occult type II EL was suspected, and treatment was performed. However, the aneurysm continued to enlarge. Thus, we diagnose with type V EL as exclusion diagnosis. We combined an aortic cuff and stent-graft leg to cover the initially inserted stent graft, as a diagnostic treatment for unrefined type IIIb EL. Subsequently, the aneurysm diameter decreased. This technique and concept may be effective for type V EL, which may include another type occult EL.

An in Vitro Twist Fatigue Test of Fabric Stent-Grafts Supported by Z-Stents vs. Ringed Stents

Whereas buckling can cause type III endoleaks, long-term twisting of a stent-graft was investigated here as a mechanism leading to type V endoleak or endotension. Two experimental device designs supported with Z-stents having strut angles of 35° or 45° were compared to a ringed control under accelerated twisting. Damage to each device was assessed and compared after different durations of twisting, with focus on damage that may allow leakage. Stent-grafts with 35° Z-stents had the most severe distortion and damage to the graft fabric. The 45° Z-stents caused less fabric damage. However, consistent stretching was still seen around the holes for sutures, which attach the stents to the graft fabric. Larger holes may become channels for fluid percolation through the wall. The ringed stent-graft had the least damage observed. Stent apexes with sharp angles appear to be responsible for major damage to the fabrics. Device manufacturers should consider stent apex angle when designing stent-grafts, and ensure their devices are resistant to twisting.

Risk factors associated with late aneurysmal sac expansion after endovascular abdominal aortic aneurysm repair

PURPOSE

We aimed to identify the risk factors associated with late aneurysmal sac expansion after endovascular abdominal aortic aneurysm repair (EVAR).

METHODS

We retrospectively reviewed contrast-enhanced computed tomography (CT) images of 143 patients who were followed for ≥6 months after EVAR. Sac expansion was defined as an increase in sac diameter of 5 mm relative to the preoperative diameter. Univariate and multivariate analyses were performed to identify associated risk factors for late sac expansion after EVAR from the following variables: age, gender, device, endoleak, antiplatelet therapy, internal iliac artery embolization, and preprocedural variables (aneurysm diameter, proximal neck diameter, proximal neck length, suprarenal neck angulation, and infrarenal neck angulation).

RESULTS

Univariate analysis revealed female gender, endoleak, aneurysm diameter ≥60 mm, suprarenal neck angulation >45°, and infrarenal neck angulation >60° as factors associated with sac expansion. Multivariate analysis revealed endoleak, aneurysm diameter ≥60 mm, and infrarenal neck angulation >60° as independent predictors of sac expansion (P < 0.05, for all).

CONCLUSION

Our results suggest that patients with small abdominal aortic aneurysms (<60 mm) and infrarenal neck angulation ≤60° are more favorable candidates for EVAR. Intraprocedural treatments, such as prophylactic embolization of aortic branches or intrasac embolization, may reduce the risk of sac expansion in patients with larger abdominal aortic aneurysms or greater infrarenal neck angulation.

Endotension following endovascular aneurysm repair

Abstract

Endovascular aneurysm repair (EVAR) is a new and minimally invasive alternative to open repair for patients with abdominal aortic aneurysm (AAA). Soon after its introduction in 1990, it was recognized that EVAR had potential and distinct advantages in the elective and emergency settings. However, long-term follow-up has shown enlargement of the AAA in a substantial percentage of patients who underwent EVAR with the original-permeability Excluder. Of interest is that sac expansion frequently occurs in the absence of endoleak, often referred to as endotension. The pathophysiology of endoleak is beginning to be elucidated and its management is ready to be established, while controversy still exists about the etiology and clinical consequences of endotension. Fortunately, the incidence of endotension is decreasing and it appears that AAA expansion after EVAR with the original Excluder can be arrested by endovascular relining with a low-permeability Excluder endoprosthesis. The aim of this brief review is to provide historical perspective and a good understanding of the etiology, diagnosis, and management of endotension.

Symptomatic seroma after open abdominal aortic aneurysm repair

Seroma following open abdominal aortic aneurysm repair has rarely been described. The majority of cases in the literature have been associated with use of polytetrafluoroethylene grafts. Here, we present a patient with a very large, symptomatic periaortic graft seroma 10 years after conventional (open) repair. The etiology of such seromas is of significant interest in endovascular aortic repair.

Continued Aortic Aneurysmal Expansion After Thoracic Endovascular Stent-Grafting

We report the successful open repair of a thoracoabdominal aneurysm that had expanded after previous endovascular stenting. Aortic valve-sparing root replacement was performed as an initial step because the patient had significant aortic valve regurgitation caused by root enlargement. Continued aneurysmal dilatation after stenting of the thoracic aorta can lead to repair failure and therefore underscores the need for careful follow-up of patients after endografting.

Five-year report of a multicenter controlled clinical trial of open versus endovascular treatment of abdominal aortic aneurysms

OBJECTIVE

Compare long-term results of endovascular treatment and standard open repair of abdominal aortic aneurysms in a multicenter, concurrent-controlled trial.

METHODS

334 subjects were treated with standard open repair (control, n = 99) or the original EXCLUDER Bifurcated Endoprosthesis (test, n = 235). Five-year clinical evaluations and corelab radiographic results are analyzed.

RESULTS

Overall and aneurysm-related survival are similar. There have been ten open conversions, most frequently for enlarging sacs without endoleak. Two patients died after conversion. Including reinterventions and complications of reinterventions as adverse events, there is significant, persistent long-term reduction in major adverse events. At 5 years, corelab reported 0% limb narrowing, 0% trunk migration, 0% component (contralateral leg, aortic extender, and iliac extender) migration, 0% fracture, endoleak in 3% (2 type II/68), and aneurysm growth (>5 mm compared to baseline) in 38% (30/78) of the test group. There are no aneurysm ruptures in either test or control group.

CONCLUSIONS

After 5 years follow-up, endovascular repair is a safer and effective treatment compared with open surgical repair for abdominal aortic aneurysms. Major adverse events are less frequent with the endograft despite the need for late reinterventions. Aneurysm expansion is observed in nearly two-fifths of patients but is not associated with endoleak or aneurysm rupture. Multicenter clinical trials are evaluating a newer version of this device designed to avoid this high rate of sac expansion.

Progressive growth of a pelvic collection five years after endovascular aneurysm repair: an atypical presentation of an asymptomatic contained rupture

We report a case of an unusual and late presentation of an asymptomatic contained rupture after modular stent-graft implantation to treat an aortobiiliac aneurysm. Follow-up computed tomography (CT) scans 4 and 5 years after endovascular aneurysm repair showed a homogeneous, nonenhancing, but clearly growing, pelvic collection. CT-guided drainage of the collection was performed, and cultures of the evacuated brown fluid were negative for any infection. Control CT scan after drainage showed a complete collapse of both the collection and the previously excluded iliac aneurysms. A direct communication between the sterile pelvic collection and the excluded iliac aneurysm was suggested on this CT imaging and confirmed afterwards by surgery. From these imaging and surgical findings, this pelvic collection can be considered as an atypical presentation of an asymptomatic contained rupture of the excluded aneurysm.

Sac enlargement due to seroma after endovascular abdominal aortic aneurysm repair with the Endologix PowerLink device

A patient who had undergone endovascular repair of an abdominal aortic aneurysm with the Endologix PowerLink bifurcated system presented with delayed aortic aneurysm enlargement due to assumed endotension. He was treated with aortic sac evacuation and wrapping of the endograft. This is the first report of endotension and aneurysm sac enlargement after implantation of the PowerLink endograft.

Endoscopic Aneurysm Sac Fenestration as a Treatment Option for Growing Aneurysms Due to Type II Endoleak or Endotension

PURPOSE

To evaluate endoscopic fenestration as a treatment option for growing aneurysm due to a type II endoleak or endotension after endovascular aneurysm repair (EVAR).

METHODS

Eight patients (7 men; median age 69 years, range 55-79) who underwent "successful" EVAR were diagnosed with a growing aneurysm due to a type II endoleak (n=4) or endotension (n=4). Surgical intervention consisted of endoscopic fenestration of the sac and removal of all the thrombus material, preceded by clipping of the inferior mesenteric and all lumbar arteries in cases of endoleak. Fluid samples from the fenestrated aneurysm sac were analyzed for the presence of microorganisms and fibrin degradation products (FDP) and/or D-dimers.

RESULTS

The median duration of operation was 220 minutes (range 111-333). There was no perioperative mortality. In one patient, the endoscopic procedure was converted to an open fenestration procedure. Seven patients had uncomplicated follow-up and a clear decrease in the diameter of the sac; one patient was converted to open repair owing to continued sac growth despite fenestration. Bacterial cultures were negative in all patients, but high levels of FDP and/or D-dimers were found in all available samples, indicating continued fibrinolysis.

CONCLUSION

Endoscopic fenestration, with or without endoscopic clipping of all side branches, seems to be an effective, reliable and minimally invasive treatment option for patients with a growing aneurysm due to type II endoleak or endotension. The high levels of FDP and/or D-dimers in the aneurysm sac are suggestive of hyperfibrinolysis, which may play an important role in aneurysm growth after EVAR.