Vascular News Medtronic supplement – January 2021

January 2021 | Educational Supplement

ChEVAR technique essentials vascularnews.com

A practical guide to chimney endovascular aneurysm repair (ChEVAR)

This educational supplement has been sponsored by Medtronic

Foreword Dear colleagues, dear readers of Vascular News, The clinical evidence on the chimney/snorkel technique has flourished in the last decade, with increasing numbers of key publications and the release of new data. However, the role of the chimney technique at different meetings has been secondary and is very often part of a debate on other therapeutic options. During the COVID-19 period, it has been possible to focus on evidence and standardisation of the procedure. In this Vascular News supplement, we will highlight clinical and scientific aspects that will provide relevant, practical advice for readers in order to optimise results and to help in the decision-making process of potential patients with inadequate neck anatomies suitable for chimney endovascular aneurysm repair (ChEVAR).

I am delighted to present to you a supplement in which we include input from various experts on the chimney technique from all over Europe. I hope you enjoy reading this supplement and that you find this information will help to optimise the performance of the chimney technique in your practice.

Yours, Konstantinos P Donas

Konstantinos P Donas is professor of vascular surgery, head of the Department of Vascular Surgery, and director of the Research Centre at Asklepios Clinic Langen, Göthe-University Frankfurt, Langen, Germany.

Contents: 3: From a bailout procedure to a standardised therapeutic option: Ten-year anniversary of the first publication of abdominal use of ChEVAR in symptomatic patients, Giovanni Torsello 4-5: Patient selection: Insights from the PROTAGORAS 2.0 study regarding adequate preoperative sizing and planning, Stefano Fazzini 6: The procedure step by step: Which are the critical moments and what should be avoided? Konstantinos Donas

8: H ow ChEVAR changed my practice with inadequate infrarenal sealing zones, Antonio Giménez Gaibar 8-9: C ase report: Complex symptomatic aortoiliac aneurysm: ChEVAR is the solution, Sébastien Déglise & Celine Deslarzes-Debuis 10-11: L atest clinical evidence on ChEVAR: What is next? Gergana T Taneva

7: How ChEVAR changed our approach in hostile AAA necks, Cornelis JJM Sikkink & Lee H Bouwman

All rights reserved. Published by BIBA Publishing, London T:+44 (0)20 7736 8788, publishing@bibamedical.com.

The opinions expressed in this supplement are solely those of Medtronic and the featured physicians and may not reflect the views of Vascular News.

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January 2021

Evolution

ChEVAR essentials

From a bailout procedure to a standardised therapeutic option: Ten-year anniversary from the first publication of the abdominal use of ChEVAR in symptomatic patients

In this article, Giovanni Torsello tracks the evolution of the chimney endovascular aneurysm repair (ChEVAR) procedure, and how it has developed from a “mere bailout solution” to a “standardised complimentary approach” in the treatment of juxtarenal abdominal aortic aneurysm (AAA).

IN 2003, ROY GREENBERG AND colleagues reported their first ChEVAR experience in the Journal of Vascular Surgery.1 This technique, originally born as a bailout solution for emergent situations, has grown in popularity in recent years. Different parallel graft methods (chimney/snorkel, periscope, sandwich) have been developed for the treatment of complex infrarenal, juxtarenal, suprarenal, thoracoabdominal, and aortic arch pathologies.2 These off-theshelf solutions have been adopted in many centres worldwide. However, the preliminary reported results were heterogeneous.

While Ohrlander, Hiramoto, and Donas3–5 reported excellent outcomes in terms of 30-day mortality and type I endoleak, higher morbidity and mortality have been described by other authors.6 The reasons for diverging results were the small number of patients included in single-centre cohorts, the wide variety of treated entities, and the varying device combinations used.

In order to better understand the value of the technique in different aortic pathologies, and also for standardisation of the procedure, thirteen European and American investigators pooled their experience with 517 cases treated by ChEVAR in the PERICLES registry.

An initial point of concern was the high rate of intraoperative type Ia endoleak.

In PERICLES,7 the type Ia endoleak rate was 7.9% on completion angiography and decreased to 2.9% by the first postoperative computed tomography angiography (CTA), demonstrating that the majority of ChEVAR gutter endoleaks can be expected to resolve spontaneously. The evaluation of the remaining persistent endoleaks were detected in patients with an insufficient length of the new proximal seal zone. Another key factor associated with a high risk of type Ia endoleak was stent graft oversizing of less than 20%.8 The type Ia endoleak rate January 2021

In this context, PERICLES also demonstrated that the risk of stent instability rises as the number of chimney stent grafts used increases. However, recent data show comparable good results in multiple chimneys when technical details are observed.11 Another point of discussion is the stroke risk after ChEVAR. This complication is related to the antegrade cannulation of the renal and visceral vessels. The use of bilateral upper extremity access was found to be an independent predictor factor associated with a 2.8-fold increased risk for postoperative stroke.12 Using a single-arm access point (e.g. left upper extremity) can reduce the stroke risk after ChEVAR procedures. In case of multiple chimneys, retrograde cannulation and periscope implantation of one or two chimneys can be an alternative, avoiding catheter manipulation at the level of the aortic arch. Further studies are necessary to validate the technique.

in this patient group was 14.3% compared to 2.1% in cases with 30% oversizing. A higher rate of gutter-related endoleaks and low oversizing was found also in patients treated in low volume centres (<20 patients treated per year), showing that experience Giovanni Torsello References plays an important role in the 1. Greenberg RK, et al. Should patients with challenging outcome of this procedure.8 anatomy be offered endovascular aneurysm repair? J Vasc Surg 2003; 38: 990–996.

Another important merit of the PERICLES 2. Kansagra K, Kang J, Taon MC, et al. Advanced endografting study is the demonstration that the materials techniques: snorkels, chimneys, periscopes, fenestrations, and branched endografts. Cardiovasc Diagn Ther 2018; play a paramount role when avoiding gutters.9 8(Suppl 1): S175–S83.

3. Ohrlander T, Sonesson B, Ivancev K, et al. The chimney graft: Unpublished data presented at the LINC a technique for preserving or rescuing aortic branch vessels Mount Sinai 2017 Endovascular Symposium in stent-graft sealing zones. Endovasc Ther 2008 Aug; 15(4): 427–32. doi: 10.1583/07-2315.1 (13–14 June, New York, USA) show that 4. Hiramoto JS. Commentary: Multiple chimney grafts for the frequency of this complication was 3.4 total endovascular revascularization of the visceral arteries in the setting of ruptured TAAA: Inventive but let’s wait for times greater in patients treated with stainless the smoke to clear on this one. J Endovasc Ther 2010; 17: steel endoskeleton compared to nitinol 222–223.

5. Donas KP, Pecoraro F, Torsello G, et al. Use of covered devices. This finding was confirmed by the chimney stents for pararenal aortic pathologies is safe and feasible with excellent patency and low incidence of PROTAGORAS study,10 showing excellent endoleaks. J Vasc Surg 2012; 55(3): 659–65. results if the flexible Endurant™ endograft 6. Coscas R, Kobeiter H, Desgranges P, Becquemin JP. Technical aspects, current indications, and results of chimney (Medtronic) is combined with high-radial grafts for juxtarenal aortic aneurysms. J Vasc Surg 2011 Jun; force balloon-expandable chimney stent 53(6): 1520–7. doi: 10.1016/j.jvs.2011.01.067. Epub 2011 Apr 22. grafts (Advanta™ V12, Getinge). The data 7. Donas KP, Lee JT, Lachat M, et al. Collected world experience have demonstrated the importance of specific about the performance of the snorkel/chimney endovascular technique in the treatment of complex aortic pathologies: device combinations to achieve good results, the PERICLES registry. Ann Surg 2015; 262(3): 546–53; discussion 52–3. not only in terms of endoleak reduction, but 8. Donas KP, Usai MV, Taneva GT, et al. Impact of aortic stentalso in chimney occlusion-free survival. Both graft oversizing on outcomes of the chimney endovascular

The ENCHANT registry will provide reliable data on ChEVAR performance.” complications are rare when nitinol-polyester endografts are used. The choice of bridging stent is also important in order to reduce additional use of relining stents, which is associated with significantly worse stent patency (p=0.014).

technique based on a new analysis of the PERICLES registry.

Vascular 2019; 27: 175–180.

9. Scali ST, Beck AW, Torsello G, et al. Identification of optimal device combinations for the chimney endovascular aneurysm repair technique within the PERICLES registry. J Vasc Surg 2018; 68(1): 24–35.

10. Donas KP, Torsello GB, Piccoli G, et al. The PROTAGORAS study to evaluate the performance of the Endurant stent graft for patients with pararenal pathologic processes treated by the chimney/snorkel endovascular technique. J Vasc Surg 2016; 63(1):1–7.

11. Taneva GT, Donas KP, et al. Results of chimney endovascular aneurysm repair as used in the PERICLES Registry to treat patients with suprarenal aortic pathologies.

J Vasc Surg 2020 May; 71(5): 1521–1527.e1.

12. Bosiers MJ, Tran K, Lee JT, et al. Incidence and prognostic factors related to major adverse cerebrovascular events in patients with complex aortic diseases treated by the chimney technique. J Vasc Surg 2018; 67(5): 1372–9.

Giovanni Torsello is a vascular surgeon at the Institute for Vascular Research, St Franziskus Hospital in Münster, Germany.

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Key data

Patient selection: Insights from the PROTAGORAS 2.0 study regarding adequate preoperative sizing and planning

Stefano Fazzini highlights key findings of the recently-published PROTAGORAS 2.0 study, concluding “aortic stent graft oversizing should be considered the most important parameter for optimal ChEVAR [chimney endovascular aneurysm repair] planning”.

RECENTLY, THE CHEVAR procedure was included in the European Society for Vascular Surgery (ESVS) 2019 guidelines for the treatment of juxtarenal abdominal aortic aneurysms (jAAA), as an alternative to fenestrated EVAR (FEVAR) in urgent settings and/or hostile anatomies (e.g. angulated aortic neck, narrow and calcified iliac access).

Despite the tremendous evolution of ChEVAR in the last decade, in terms of important publications (such as PERICLES and PROTAGORAS) and worldwide spread, the gutter-related endoleak (type Ia endoleak) is still considered the Achilles’ heel of the technique by many authors.

One of the reasons for this perception is the concerning results comparing ChEVAR with FEVAR, showing that the former has a higher rate of late type Ia endoleak.

Some authors have suggested that new research should focus on improvements in the preoperative planning, in order to avoid significant divergent experiences with this approach.

As a bailout and not-standardised procedure, ChEVAR cannot be compared with FEVAR in terms of preoperative planning, because many challenging anatomical aspects must be taken into account with ChEVAR. At the same time, physicians performing ChEVAR should be dealing with urgent cases and hostile anatomies.

The new era of the ChEVAR technique, named ‘standardisation’, could be realised by easy/customised planning and an ideal chimney–graft combination.

Most of the published data have been evaluated by in vitro experiences focusing on gutter-related endoleaks and chimney graft compression, which is supposed to influence flow profile and may induce a risk of stent thrombosis.

To overcome the technical bias of in vitro

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studies (silicon models with one standard chimney graft morphology), we decided to analyse a homogeneous cohort of patients with single/double chimney grafts involving only one device combination: the Medtronic Endurant stent graft combined with a balloon-expandable stent graft (Advanta V12, Getinge). This choice allowed us to evaluate many challenging anatomies, such as a hostile neck (reverse tapered, angulated) and access (narrowed and calcified).

We performed a computed tomography angiography (CTA)-based evaluation of a 10-year Münster experience with ChEVAR. With PROTAGORAS 2.0 (European Journal of Vascular and Endovascular

We advise an oversizing of 30–40% to avoid persistent type Ia endoleaks and likewise to ensure chimney graft patency.”

Surgery, article in press) for the first time, a single parallel graft combination was evaluated using late outcomes and CTA-based pre/postoperative imaging in order to identify significant predictors to optimise sizing and prevent persistent type Ia endoleaks and chimney grafts stenosis/ occlusion.

A recommended new range for main graft sizing, a new composite parameter (L-OS), and the concept of lost neck are the main elements of novelty for ChEVAR planning.

A central finding of this study was that a

main graft oversizing between 30 and 40% (Figure 1) was significantly associated with a freedom from type Ia endoleak-related reintervention, without compromising primary chimney graft patency. Wide necks (>29mm) were significantly related to type Ia endoleaks having a mean oversizing of less than 20%; inversely, narrow diameters (<20mm) were significantly related to chimney graft stenosis/occlusion caused by excessive oversizing of more than 50%.

The mean diameter of sealing zone (three aortic cross-sections of total neck length) should be taken into consideration in order to select the aortic stent graft diameter (Figure 2). In contrast to the actual recommendations of 20–30%, the optimal main graft oversizing seems to be higher, at around 30%. In fact, oversizing of at least 30–35% should be used for single and double chimneys, respectively.

Stefano Fazzini The turbulence of blood flow at the level of the gutters should induce a spontaneous resolution of flow, proportional to the length and inversely proportional to the gutter area. Despite this general belief, a total neck length >20mm could not guarantee the sealing of early and late endoleaks in this study, if the oversizing was not adequate.

In the present analysis, oversizing was the only significant independent parameter to prevent late type Ia endoleak. The presence of infrarenal neck was the only factor preventing type Ia endoleaks; in the case of no infrarenal neck, an oversizing of more than 35% would be needed to minimise the risk of persistent gutters.

Another novelty of our research was the presentation of a new composite parameter (L-OS: total neck length [mm] + oversizing [%]) in order to reflect more accurately the successful preoperative planning. It could be a useful tool for uncertain cases (the choice of stent graft sizing leading to a wide gap of oversizing, e.g. 32/36mm resulting in 23/38% oversizing for a neck diameter of 26mm) to find a compromise between a short neck and aggressive oversizing, single or double chimney grafts. An L-OS range of 55–65 was significantly related to freedom from persistent type Ia endoleak and primary chimney graft patency.

Considering that we treated 86% of hostile necks, the higher ranges (OS>35 and L-OS>60) could be indicated for double January 2021

ChEVAR essentials

Figure 1. Key parameters for sizing of ChEVAR procedures with single/double chimney grafts.

Figure 2. Aortic neck diameter is measured as the mean of three aortic cross-sections of the sealing zone (proximal, middle, distal segment).

chimney grafts and hostile parameters as pararenal neck or infrarenal angulation >60 degrees (Figure 3).

An additional finding of the current study was the estimation of the lost neck, considering that the ideal and available total neck length is not always achieved; even in the case of very precise deployment, some amount of neck (mean of 3mm) could be lost during the procedure, caused by the presence of the sheaths in place and/or very angulated anatomy.

Finally, the association between these two devices, the most used in the published literature, seems to result in optimal clinical outcomes, combining the flexibility of Endurant stent grafts and high patency rate of Advanta V12. Our imaging-based analysis confirm the benefit of the high conformability at the level of the transition zone between the aortic neck and the proximal portion of the aneurysm, thanks to short M-shaped stents of Endurant stent grafts.

Our experience suggests that aortic stent graft oversizing should be considered the most important parameter for optimal ChEVAR planning. The total neck length seems not effective to guarantee the sealing without an adequate oversizing.

In conclusion, as far as the usage of the Endurant stent graft and Advanta V12 is concerned, we advise an oversizing of 30– 40% to avoid persistent type Ia endoleaks and likewise to ensure chimney graft patency. In case of double chimney grafts and/or hostile neck features, greater degrees of oversizing should be planned. A 20– 25mm total neck length should be suggested considering the amount of lost neck, higher in angulated anatomies. The pararenal and wide necks seem to be the main risk factors for endoleaks.

Stefano Fazzini is a researcher and vascular surgeon in the Department of Vascular and Endovascular Surgery at “Tor Vergata” University of Rome in Rome, Italy.

Figure 3. The easy customisation for ChEVAR sizing. The main hostile neck parameters are considered pararenal, angulated (>60°), hostile shape (reverse tapered), and calcified (>50%) neck.

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Procedure guide

The procedure step by step: Which are the critical moments and what should be avoided?

In this step-by-step guide, Konstantinos P Donas outlines the chimney endovascular aneurysm repair (ChEVAR) technique from access to further treatment considerations, detailing various crucial moments and offering a range of tips and tricks to ensure a successful procedure.

THE CHEVAR TECHNIQUE increases the risk of occlusions is demanding and requires due to the placement of more advanced endovascular skills. material in a small (6mm or less) It involves a minimum of two target vessel. access points: femoral and The second critical moment is an upper extremity. Femoral to deploy the chimney graft in access can be completed in a the middle of the suprarenal stent percutaneous fashion. One or both of the abdominal device (Figures upper extremities, preferably the 1–3). The chimney graft should left side, are accessed dependent be protected and not be in contact Konstantinos P on the number of chimney grafts with the pins of the suprarenal planned. A preoperative computed Donas stent. In the removal of the tomography angiography (CTA) balloon of the chimney graft after of the thoracic aorta and the subclavian deployment in particular, the sheath should arteries is paramount in order to exclude be below or just at the level of the pins of the the presence of soft plaques and thrombotic suprarenal stent, protecting the balloon of lesions, which can lead to stroke or the chimney graft from the pins in order to embolisation of the visceral arteries. avoid the risk of trapping the balloon with the An open approach to the axillary artery suprarenal pins of the abdominal device. is utilised in the majority of cases. We gain The next crucial moment is to perform proximal and distal control of the axillary artery, and single or double puncture of the vessel can be performed at a distance of 1–2cm. After changing the short 5F sheaths for 90cm 7F sheaths, we perform a selective catheterisation of the involved target vessels.

Here is the first critical periprocedural moment; the sheath followed by the chimney graft should be advanced in the target vessels only over a stiff wire with an atraumatic curved tip. Particularly where there is friction or stenosis of the orifice of the target kissing ballooning between the aortic stent vessels, there is a risk of injury to the kidney graft and the chimney graft at the end of the parenchyma when using stiff wires with stiff procedure. This manoeuvre is very important tips. because it improves the conformability of the Once the selected branches have wires in abdominal device and the chimney grafts. place, the aortic endograft is deployed and, Here it is crucial to deflate the balloon of subsequently, each chimney graft should the chimney graft only after the complete have the proximal edge in the middle of deflation of the balloon in the aortic stent the suprarenal stent of the aortic endograft, graft. Otherwise, there is a risk of creating a extending at least 10–15mm inside the target stenosis of the chimney graft, which is not vessel. Angulated renal arteries are at risk of per se crush resistent from the balloon of the severe stenosis and kinking of the chimney aortic stent graft if the balloon of the chimney grafts, in the case of deep placement and graft is deflated first. involvement of the angulated segment of The next crucial moment during the the renal arteries. Additional deployment procedure is the reaction of the physician in of flexible nitinol stents or covered stents case of type Ia endoleak at the completion

The ChEVAR technique is demanding and requires advanced endovascular skills.”

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Figure 1. There is a risk of complication from trapping the sheath with the pins of the suprarenal stent.

Figure 2. There is a risk of capturing the balloon of the chimney graft with the pins.

Figure 3. The ideal position of the sheath, protecting the balloon from the pins, for when we decide to remove the balloon.

angiography. How aggressive should further treatment be; should we deploy a cuff; should we use endoanchors or not? The main rationale for the decision is to admit that type Ia endoleaks caused by the gutters is common during the procedure. The question is, which case will need additional treatment and which case will undergo radiological surveillance?

Preoperative planning is key to the eradication of potential gutter-related endoleaks. As clarified in the previous article from Fazzini, aggressive oversizing of 30% in single chimneys and 35% in double chimneys, and a new seal zone of at least 20mm in length, are important considerations in preoperative planning. Within these parameters, any gutter-related endoleak at the completion angiography will dissapear in the in-hospital CTA. Konstantinos P Donas is professor of vascular surgery, head of the Department of Vascular Surgery, and director of the Research Centre at Asklepios Clinic Langen, Göthe-University Frankfurt, Langen, Germany.

January 2021

Experience

ChEVAR essentials

How ChEVAR changed our approach in hostile AAA necks Cornelis JJM Sikkink and Lee H Bouwman detail how chimney endovascular aneurysm repair (ChEVAR) has changed their approach in hostile abdominal aortic aneurysm (AAA) neck management, summarising that a standardised approach has been a key factor to ensure procedural success.

CHEVAR HAS BEEN PRESENT IN endovascular specialists’ armamentarium for many years, but has always been relegated to a bailout option due to lack of a standardised approach reflected in contradicting published evidence. Further resistance to the technique was due to concerns regarding gutters and intraoperative endoleaks.

The PERICLES study helped to clarify multiple aspects, such as the spontaneous resolution of gutter endoleaks when oversizing and new sealing zone requirements are correctly applied.

Additionally, multiple benchmodel studies have reported Endurant (Medtronic) and Advanta V12 (Getinge) to morphologically adapt well to each other, reducing gutter areas and minimising stent compression.1–3 Further contribution to a standardised approach was achieved in 2016, when Medtronic received CE mark for the Endurant II/IIs stent graft system to treat patients with AAA using ChEVAR, based on the clinical findings of the PROTAGORAS trial.4 The ongoing ENCHANT multicentre prospective trial is set to add further robust evidence that might support future therapy guidelines.

At our hospital, we are participating in the ENCHANT trial and have enrolled several patients over the last three years. Early results of these patients are promising but more long-term outcomes are desired.

To be noted, 2019 AAA treatment guidelines from the European Society for Vascular Surgery now recommend ChEVAR

in urgent cases and when fenestrated repair is unfeasible or contraindicated.

In our institution, we started to adopt ChEVAR because we were regularly confronted with patients with short Cornelis JJM Sikkink and hostile necks, who were not ideal candidates for open surgical repair. We wanted an easy off-theshelf alternative in cases with inadequate infrarenal sealing zones where EVAR was not feasible and fenestrated EVAR (FEVAR) was excluded due to anatomical or logistical factors, for instance in semi-emergency cases. Although not determinative, economic factors are also evident. The main advantages we see, compared to custom-made solutions, are the immediate availability, fewer access problems due to the smaller profile, and the

Figure 1. CT angiogram of a patient with a hostile neck 7mm long.

Figure 2. Final intraoperative angiogram, with patent renal stents and the stent graft just below the SMA.

January 2021

We feel that this technique is of particular value in the patients with infrarenal aortic necks between 3–8mm in length.”

possibility of gaining a long suprarenal sealing zone with a relatively easy approach compared to use of a fourfenestrated stent graft. We feel that this technique is Lee H Bouwman of particular value in patients with infrarenal aortic necks between 3–8mm in length.

In conclusion, in our experience the chimney technique remains an effective complementary alternative modality in inadequate infrarenal sealing zones and a standardised approach has been a key factor to ensure ChEVAR success.

References 1. Donas KP, Usai MV, Taneva GT, et al. Impact of aortic stentgraft oversizing on outcomes of the chimney endovascular technique based on a new analysis of the PERICLES registry.

Vascular 2019; 27: 175–180.

2. Donas KP, Lee JT, Lacaht M, et al. Collected world experience about the performance of the snorkel/chimney endovascular technique in the treatment of complex aortic pathologies: the PERICLES registry. Ann Surg 2015; 262: 546–553.

3. Mestres G, Uribe JP, Garcia-Madrid C, et al. The best conditions for parallel stenting during EVAR: an in vitro study.

Eur J Vasc Endovasc Surg 2012; 44: 468–473.

4. Donas KP, Torsello GB, Piccoli G, et al. The PROTAGORAS study to evaluate the performance of the Endurant stent graft for patients with pararenal pathologic processes treated by the chimney/snorkel endovascular technique. J Vasc Surg 2016; 63: 1–7.

Cornelis JJM Sikkink and Lee H Bouwman are vascular surgeons at the Zuyderland Medical Center in Heerlen, The Netherlands.

Figure 3. 3D reconstruction, four weeks after the procedure; patent vessels/stents, no endoleak.

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Experience

How ChEVAR changed my practice with inadequate infrarenal sealing zones

Antonio Giménez Gaibar discusses his team’s positive experience with chimney endovascular aneurysm repair (ChEVAR), and highlights future research that might introduce further evidence in support of the technique.

EVAR IS A MINIMALLY INVASIVE method for treating infrarenal abdominal aortic aneurysms (AAAs), especially for patients with severe comorbidities. However, between 30–40% of patients are unsuitable anatomic candidates for conventional EVAR, mostly due to a challenging proximal aortic neck anatomy.

Several endovascular techniques have been proposed to ensure a secure proximal landing zone in AAA with hostile necks. The conceptual basis for these complex cases involves cranial extension of the proximal seal zone with preservation of branch vessel patency. ChEVAR and fenestrated (FEVAR) or branched EVAR (BEVAR) are most commonly used.

One advantage of ChEVAR is its immediate availability. Before the approval of custom fenestrated devices by the US Food and Drug Administration (FDA) in 2012, homemade fenestrated and chimney techniques were developed to treat urgent or bailout-type interventions with an allendovascular procedure. This technique can currently be used to treat AAAs with short necks, type Ia endoleaks after EVAR, as well as juxtarenal and pararenal endovascular repairs. It is also recommended when FEVAR/BEVAR would entail unacceptable cost, manufacturing delays, or for patients deemed unsuitable for custom-made devices, especially in tortuous aortic anatomy or in

Case report: Complex symptomatic aortoiliac aneurysm: ChEVAR is the solution 8

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challenging iliac artery access.

Our team started using ChEVAR in high-risk patients for open surgery with short neck and inadequate sealing zone for standard EVAR. As a rule of thumb, we applied 20–30% oversizing in all cases, with a tendency to oversize closer to 30%, as suggested by the most recent evidence, in cases requiring more than one chimney.

Balloon-expandable covered stents have been used as chimney grafts. The length of the proximal landing zone dictates which renal

and/or visceral vessels require coverage, and thus the number of snorkel grafts needed.

A sealing ring below the chimney grafts would be desirable for technical success. Our hypothesis is that owing to this sealing ring, the gutters run blind and produce thrombosis.

Furthermore, a discrepant origin of the two renal arteries would be advisable to indicate ChEVAR. Published results confirm that ChEVAR can be applied in a variety of clinical situations with a high degree of technical success. It has been established as a useful, safe, and effective technique for cases not suitable for the current commercially available branched or fenestrated devices and it provides an immediate off-the-shelf solution. We believe that the ongoing ENCHANT trial may introduce further evidence to support this technique.

Antonio Giménez Gaibar is director of the Department of Vascular Surgery at the Hospital Universitari Parc Tauli in Barcelona, Spain.

Figure 1. a, b: Preoperative CT-scan AAA with hostile neck anatomy; c, d: Postoperative onemonth CT-scan.

Sébastien Déglise and Celine Deslarzes-Dubuis outline a case study involving the successful use of chimney endovascular aneurysm repair (ChEVAR). In the discussion of their experience, Déglise and DeslarzesDubuis note that, despite many advantages, ChEVAR continues to face “high resistance,” and argue that “choice of the technique should be dictated more by the patient, the clinical circumstances, and the anatomical characteristics rather than by personal beliefs”.

Case

A 68-year-old man known for cardiac insufficiency, atrial fibrillation, hypertension, strokes, and active smoking, presented to the Emergency Department with abdominal and back pain.

The computed tomography angiography (CTA) scan revealed signs of perianeurysmal fat infiltration and fast growth of a known juxtarenal abdominal aortic aneurysm from 32 to 50mm. Due to his frailty related to severe comorbidities, open surgery was contraindicated. However, the presence of a short conical neck with circumferential thrombus (Figure 1) precluded any standard January 2021

ChEVAR essentials

Figure 1. a: Infrarenal conical neck with circumferential thrombus; b: 3D reconstruction showing infrarenal angulation and downward left renal artery.

Figure 2. Intraoperative images showing the two chimneys with the Endurant IIs device (a) and completion angiogram (b).

Figure 3. a: Postoperative 3D-CTA showing ChEVAR and IBD on the right with patent chimneys; b. absence of any gutter endoleaks.

endovascular aneurysm repair (EVAR). The suprarenal aorta was healthy and could offer a good proximal sealing zone. Moreover, the distal landing zone was complex, with occlusion of the left internal iliac artery and a 25mm distal common right iliac artery. Both accesses were suitable for EVAR. Given the thrombotic and conical neck anatomy, it was decided to seal above the renal arteries by doing a ChEVAR. Indeed, fenestrated EVAR (FEVAR) could not be considered due to the acute symptoms of a pre-rupture state in this patient. We opted for an iliac branch device on the right side due to an ectatic iliac artery and the risk of further dilatation due to a bell-bottom stent graft. Regarding the chimneys, two BeGraft covered balloonexpandable stents of 6 and 7mm in diameter (Bentley InnoMed) were placed in each renal artery from a left axillary approach using two separate 7F Destino™ Twist long deflectable steerable guiding sheaths (Oscor) parallel to the 32mm Endurant IIs (Medtronic) mainbody. An iliac branch device (IBD) was then placed on the right side and another BeGraft covered stent was deployed in the right hypogastric artery form the left upper access. One Endurant II (Medtronic) limb extension was used as a bridge between the main body and the IBD and another was placed on the left side in order to seal in the external iliac artery. Completion angiogram showed neither any gutter nor any other endoleaks. The chimneys were widely open, as well as the iliac branch device (Figure 2). Patient had an uneventful recovery and follow-up CTA confirmed the good initial results with an excluded aneurysm, no endoleaks, and patent chimneys (Figure 3).

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Discussion

The chimney technique made itself known as a bailout procedure to save covered arterial branches during EVAR. With growing experience, the ChEVAR technique made a name for itself among the years thanks to various advantages. In 2015, the PERICLES registry offered the first world evidence of excellent and robust results of this technique in patients with complex aneurysm anatomy.

However, the durability of this technique remained a matter of debate mainly because of gutter endoleaks. The PERICLES investigators, however, found that those gutters were benign and disappeared on the first postoperative CTA in the majority of the patients with the respect of a 30% oversizing and a >20mm new sealing zone. The next step in the development of this strategy was the CE mark that Medtronic obtained in 2016 with its Endurant II/IIs system combined with balloon-expandable covered stents.

Despite numerous well-known advantages, like its off-the-shelf availability and the fact that it does not require many resources, ChEVAR continues to face high resistance, especially among FEVAR supporters.

However, these two strategies have to be considered as complementary rather than in opposition. The choice of the technique should be dictated more by the patient, the clinical circumstances, and the anatomical characteristics rather than by personal beliefs.

In our case, many parameters spoke in favour of ChEVAR. The first point to take into consideration was the presence of symptoms leading to an emergent intervention precluding the use of any custom-made device. One could argue that an off-the-

shelf multibranch stent graft could solve this problem, but with an increased zone of aortic coverage and therefore a higher risk of spinal cord ischaemia and its potential devastating consequences. Indeed, ChEVAR allows for sealing in a healthy zone of aorta but with as minimal coverage as possible.

Another point was the relatively steep trajectory of the left renal artery associated with some degree of angulation of the aorta.

In these circumstances, precise deployment of a fenestrated stent graft and cannulation of the target vessel from below through the fenestration could be very challenging.

This was not the case from above for the left chimney, especially when using a deflectable, steerable sheath. Finally, the technical configuration of the Endurant II/ IIs system allows for an easy combination with others components, such as an IBD, to ensure an optimal final result. All of these advantages led the European Society for Vascular Surgery (ESVS) to recommend the ChEVAR technique in urgent cases when a fenestrated procedure is contraindicated in their recently published abdominal aortic aneurysm treatment guidelines. The ongoing international multicentre prospective ENCHANT trial will add knowledge and further evidence to consolidate the role of the ChEVAR technique in complex aneurysms management.

Sébastien Déglise and Celine DeslarzesDubuis are vascular surgeons at the University Hospital of Lausanne (CHUV) in Lausanne, Switzerland.

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E-learning

Latest clinical evidence on ChEVAR: What is next?

Writing that clinical evidence on chimney endovascular aneurysm repair (ChEVAR) has “flourished” in the last decade, Gergana T Taneva highlights key elements of the most recent research on the technique.

CHEVAR HAS SHOWN comparable results to fenestrated EVAR (FEVAR) for the treatment of juxtarenal abdominal aortic aneurysms (jAAA).1–3 The clinical evidence on ChEVAR has flourished in the last decade, with an increasing number of key publications released within recent years.4–8 ChEVAR has gained popularity to the point that its role within the AAA treatment algorithm is considered complementary depending on a patient’s characteristics and aortoiliac anatomy.9 However, cost-

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effectiveness issues, long-term outcomes, and procedural tips such as the deal with angulated renal arteries remain unknown.

In this context, we present an overview of the latest evidence and publications on these appealing topics (Table 1).

1. Widely spoken of and much needed, a cost analysis and comparison of both techniques, ChEVAR and FEVAR, was performed, evaluating all elective and symptomatic patients treated at St Franziskus Hospital in Münster, Germany, for jAAA by single or double chimney (n=111) or by FEVAR with three fenestrations (n=37) between 2013 and January 2017.10 The cost-effectiveness analysis was defined as the summary of material costs, in-hospital costs, and additional costs due to procedurerelated reinterventions. Index procedure and hospitalisation median costs were higher for FEVAR (€42,116 vs. €22,171, p<0.001). The median overall costs, including costs after reinterventions during follow-up, remain higher for FEVAR (€42,128 vs. €22,872, p<0.001) for a follow-up period of almost four years.10 Six patients (5.4%) in the ChEVAR group required readmission compared to three

patients (8.1%) who required readmission for reinterventions in the FEVAR group (p=0.69). Both FEVAR and ChEVAR proved to be expensive and technicallydemanding interventions for the treatment of juxtarenal aortic pathologies.

However, ChEVAR was significantly more cost-effective compared to FEVAR at comparable readmission rates for reinterventions.11 2. Also highly-anticipated, and extension of the follow-up and long-term evaluation of the multicentric PERICLES Registry was performed analysing clinical and radiographic data from patients treated with ChEVAR between 2008 and 2014.12 A subgroup of 244 patients with 387 chimney grafts placed and follow-up of at least 30 months was used to analyse specific anatomic and device predictors of adverse events. In the subgroup, the technical success was 88.9%, while primary patency was 94%, 92.8%, 92%, and 90.5% at two-and-a-half years, three years, four years, and five years, respectively. Mean aneurysm sac regression was 7.8±11.4mm, p<0.0001. Chimney graft occlusion occurred in 24 target vessels (6.2%).

Late open conversion was required in January 2021

Future research

ChEVAR essentials

five patients for endograft To investigate the outcomes, we infection (n=2), persistent evaluated all elective patients type 1a endoleak (n=2), and treated at St Franziskus Hospital endotension (n=1). This in Münster, Germany, over nine analysis of the PERICLES years (January 2009–December Registry provided the missing 2017) with placement of Advanta long-term experience on the V12 (Getinge) as chimney ChEVAR technique. It showed graft in combination with the favourable results with over Endurant stent graft (Medtronic) half of the patients surviving as abdominal endograft.13 A total for more than five years. Up Gergana T Taneva of 116 patients were included, to 48 months’ follow-up, the with lining performed in 43 stented vessels remained patent in over vessels for 32 patients. Lining was not 92% of the cases. The absence of infrarenal performed to increase the radial force of neck and a proximal sealing zone diameter the covered stents. The subgroup analysis >30mm were significantly associated with revealed significantly higher primary long-term device-related complications and patency within the non-lined group with poorer outcomes in terms of persistent (96.9%) at one year versus the lined group type 1a endoleak. The evidence advocated (77.1%; p=0.001).13 Lining represented the anatomical limits of the technique, a risk factor for chimney graft occlusion demanding adequate preoperative planning (odds ratio 9.9; p=0.006).13 This singleand indication. centre nine-year ChEVAR experience 3. The cause of much speculation, chimney with more than 110 Advanta V12 chimney graft lining in the case of highly angulated stents showed durable results. However, renal arteries was evaluated as a risk factor lining in angulated renal arteries showed for occlusion. Lining for deployment of a significantly higher risk for chimney an additional stent and smoothening the graft occlusion.13 These data highlight the transition in a branched vessel are normally importance of finding new ways to achieve performed when the distal part of the better conformability of the stent grafts chimney graft is seen within an angulated within the target vessel. segment of the target vessel. Typically, The presented clinical evidence contributes an additional bare metal nitinol stent is to broaden the global knowledge on the placed to improve the flexibility and even chimney technique, clarifying several major the transition. In order to minimise the issues such as cost comparison with FEVAR, reduction of the patent lumen by deploying long-term performance evidence of the an additional device, we preferred the use largest related registry, and the issue of lining of bare metal instead of covered stents. contributing to stent graft occlusion. Further

Cost-effectiveness analysis of chimney/snorkel versus fenestrated endovascular repair

Long-term chimney EVAR experience within the PERICLES registry

Use of balloonexpandable chimney grafts is durable, though caution is required when lining angulated renal arteries

Journal

J Cardiovasc Surg (Torino)

J Vasc Surg

J Endovasc Ther

Year of publication

2020

2020

2020

Main findings

ChEVAR was significantly more cost-effective at comparable reintervention rates

ChEVAR showed favourable longterm patency and patient survival rates

Lining represented a risk factor for chimney graft occlusion

Topic

research is paramount to expand and confirm the cited findings.

References 1. Taneva GT, Criado FJ, Torsello G, Veith F. Results of chimney endovascular aneurysm repair as used in the PERICLES Registry to treat patients with suprarenal aortic pathologies 2014: 1–8. Doi: 10.1016/j.jvs.2019.08.228.

2. Donas KP, Lee JT, Lachat M, et al. Collected world experience about the performance of the snorkel/chimney endovascular technique in the treatment of complex aortic pathologies: The PERICLES registry. Ann Surg 2015; 262(3): 546–52. Doi: 10.1097/SLA.0000000000001405.

3. Ronchey S, Fazzini S, Scali S, et al. Collected transatlantic experience from the PERICLES Registry: Use of chimney grafts to treat post-EVAR type Ia endoleaks shows good midterm results 2018. Doi: 10.1177/1526602818782941.

4. Ballesteros-Pomar M, Taneva GT, Austermann M, et al.

Successful management of a type B gutter related endoleak after chimney EVAR by coil assisted onyx embolisation.

EJVES Short Reports 2019; 42: 38–42. Doi: 10.1016/j. ejvssr.2018.12.002.

5. Bosiers MJ, Tran K, Lee JT, et al. Incidence and prognostic factors related to major adverse cerebrovascular events in patients with complex aortic diseases treated by the chimney technique. J Vasc Surg 2018; 67(5): 1372–9. Doi: 10.1016/j. jvs.2017.08.079.

6. Donas KP, Criado FJ, Torsello G, et al. Classification of chimney EVAR-related endoleaks: Insights from the PERICLES Registry. J Endovasc Ther 2017; 24(1): 72–4. Doi: 10.1177/1526602816678994.

7. Torsello G, Usai MV, Scali S, et al. Gender-related outcomes of chimney EVAR within the PERICLES Registry. Vascular 2018; 26(6): 641–6. Doi: 10.1177/1708538118797448.

8. Donas KP, Usai MV, Taneva GT, et al. Impact of aortic stent-graft oversizing on outcomes of the chimney endovascular technique based on a new analysis of the PERICLES Registry. Vascular 2019; 27(2): 175–80. Doi: 10.1177/1708538118811212.

9. Donas KP, Eisenack M, Panuccio G, et al. The role of open and endovascular treatment with fenestrated and chimney endografts for patients with juxtarenal aortic aneurysms. J Vasc Surg 2012; 56(2): 285–90. Doi: 10.1016/j. jvs.2012.01.043.

10. Taneva GT, Donas KP, Pitoulias GA, et al. Cost-effectiveness analysis of chimney/snorkel versus fenestrated endovascular repair for high-risk patients with complex abdominal aortic pathologies. J Cardiovasc Surg 2019. Doi: 10.23736/S00219509.19.11146-9.

11. Taneva GT, Donas KP, Pitoulias GA, et al. Cost-effectiveness analysis of chimney/snorkel versus fenestrated endovascular repair for high-risk patients with complex abdominal aortic pathologies. J Cardiovasc Surg (Torino) 2019; 60(0): 1–6.

Doi: 10.23736/S0021-9509.19.11146-9.

12. Taneva GT, Lee JT, Tran K, et al. Long-term chimney/snorkel EVAR experience for complex abdominal aortic pathologies within the PERICLES Registry. J Vasc Surg 2020;(S07415214(20)32496-4). Doi: 10.1016/j.jvs.2020.10.086.

13. Taneva GT, Fazzini S, Pipitone MD, et al. Use of stainlesssteel , balloon-expandable chimney grafts is durable though caution is required when lining angulated renal arteries. J Endovasc Ther 2020; 27(6): 902–9. Doi: 10.1177/1526602820948260.

Gergana T Taneva is a vascular surgeon at the University Hospital Puerta de Hierro in Madrid, Spain, and research leader of the Research Centre at Asklepios Clinic Langen, Göthe-University Frankfurt, Langen, Germany.

Table 1. Overview of the latest evidence and publications on cost-effectiveness issues, long-term outcomes, and lining of chimney stent grafts.

The content of these articles is meant for general information purposes only and should not be construed as a promotion or solicitation for any product or for an indication for any product which is not authorized by the laws and regulations of the country where the reader resides. The views and opinions expressed therein should be interpreted as personal views. They are completely independent and do not necessarily reflect the opinions of Medtronic. As a health care provider, you should use your own professional judgment in evaluating the information provided and rendering any medical opinion or advice. Your use of and any reliance on such information is solely at your own risk and responsibility. Medtronic makes no representation or warranty, express or implied, including any warranty of accuracy, completeness, or usefulness of any information described in these articles and Medtronic assumes no liability for the use of the information in any manner whatsoever.

See the device manual for information regarding the instructions for use, indications, contraindications, warnings, precautions, and potential adverse events.

January 2021

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