Parallel Stent Graft Techniques to Facilitate Endovascular Repair in the Aortic Arch 35 Frank J. Criado Introduction Whether using a traditional open-chest approach or endovascular techniques, the arch remains a big challenge in thoracic aortic surgery, and this is mostly related to the presence of critical branches the supra-aortic trunks. The need to preserve flow into these branches represents a notorious potential impediment to endografting [1]. Historically, the so-called chimney grafts emerged as bailout and rescue technique in the effort to preserve or revascularize branches that were inadvertently covered by the endograft [2, 3]. This was certainly true in the author s first arch chimney case, performed in April 2003, when a left common carotid artery (LCCA) chimney stent was deployed via retrograde cervical puncture in the course of endovascular repair of a dissecting thoracic aneurysm that resulted in unintentional coverage of the left carotid artery [4 6]. Chimney graft techniques have evolved significantly over the past 15 years, alongside developments with fenestrated and branched endograft devices that are meant to address some of the same issues [7]. Other terms in use to characterize chimney techniques include snorkels, periscopes, and sandwich grafts. I believe the best all-encompassing term is parallel stent grafts (PGs) [8, 9]. Almost immediately after the initial reports, chimneys and PGs were recognized as clearly useful bailout resources, but not without significant downsides and possible complications mainly those related to the breakage of the seal at F.J. Criado (*) Department of Vascular Surgery, MedStar Union Memorial Hospital, 3333 N. Calvert St., Suite 560, Baltimore, MD 21218, USA e-mail: frankjcriado@gmail.com the fixation zone and the creation of gutters at the interface between the PG conduit and the intra-aortic endograft leading (potentially) to development of a type 1 endoleak. Published reports have substantiated these fears [10], but showing also wide variability in the rates of gutter-related endoleaks [11, 12]. The aortic segment involved, the number of chimney grafts in the same segment, and the type of PG conduit and aortic endograft used have all been identified as influential factors. This realization and the paucity of data containing high-level evidence have combined to relegate chimneys and PG techniques to a place of inferiority in the minds of some experts who continue to feel their use can be justified only in the context of branch vessel rescue or urgent cases, but refuse to consider their use reasonably in elective situations where other more traditional and accepted forms of arch management strategies are available [10]. This picture is beginning to change, though, as additional recent publications have shown increasingly the undeniable utility of PGs and a lower-than-expected complication rate especially type I endoleak that would appear to be less common than once feared [12]. The techniques have thus been proclaimed to be viable or acceptable treatment options in the aortic arch, pararenal, and iliac segments by many respected authors and experts in the aortic endografting field around the world [13]. Moreover, their off-the-shelf availability makes them particularly attractive to operators and centers without experience with or access to fenestrated and branched stent graft technologies that are arguably more resource intensive. The techniques described in this chapter reflect the author s personal experience and lessons learned from others. It is meant to offer readers a relatively simple how-to guide on the fundamental technical principles and procedural steps leading to successful execution. However, caution must be exercised at the time of choosing one of these PG techniques versus a more traditional approach to arch branch management for a given patient and especially so in the context of an elective procedure. Mayo Foundation for Medical Education and Research 2017 G.S. Oderich (ed.), Endovascular Aortic Repair, DOI 10.1007/978-3-319-15192-2_35 543
544 Basic Principles Not unexpectedly, there is wide variability in the choice of PG conduit and other technical aspects. But the following guidelines should prove useful: While bare-metal stents have worked well in our hands for some simple cases, there is now near consensus that in most situations a covered stent (stent graft) device should be used. Balloon-expandable chimneys (i.e., icast) are preferred where a short PG conduit will suffice (i.e., in the LCCA) and, especially, in areas exposed to severe compressive forces and possible crushing (i.e., the origin of the LSA). Self-expanding conduits (i.e., the Viabahn device) are widely used where a long PG conduit is needed. The greatest disadvantage of the chimney/pg technique relates to the breakage of the seal zone and creation of gutters. The problem can be mitigated or avoided altogether by placing the chimney across a long (2 cm or more) seal zone or by avoiding crossing such area altogether (see description of the LSA periscope technique). Techniques Techniques of parallel stent grafts can be used as a primary method to extend the proximal landing zone in patients with thoracic or distal arch aneurysms or as a bailout maneuver if there is inadvertent coverage of one of the supra-aortic trunks. These techniques are summarized below according to the Zones of Ishimura and which of the supra-aortic trunks is targeted by the parallel stent. Zone 2 Deployment Zone 2 arch deployment is needed in patients undergoing thoracic endovascular aortic repair (TEVAR) for thoracic aortic aneurysms and dissections that extend into the distal arch and require coverage of the left subclavian artery. In these cases, access is established into the left upper extremity using either a trans-brachial percutaneous approach (Fig. 35.1a, inset) or, occasionally, via surgical cutdown exposure. A Glidewire and 5Fr catheter are advanced into the ascending aorta via the brachial approach, while transfemoral access is established into the aortic arch. The Glidewire is exchanged for a stiff 0.035-in. wire for advancement of the thoracic stent graft (Fig. 35.1b). The thoracic endograft is advanced into position in the aortic arch, while a hydrophilic F.J. Criado sheath and a chimney stent are delivered to the target position in the LSA (Fig. 35.1c). The thoracic device is deployed just distal to the origin of the left common carotid artery, covering the origin of the LSA (Fig. 35.1d). The LSA sheath is withdrawn to expose the stent (Fig. 35.1e g). Selective angiography can be performed via the sheath to demonstrate the origin of the left vertebral artery prior to stent deployment. The LSA chimney-covered stent is deployed fully (Fig. 35.1h). A short balloonexpandable covered stent (e.g., icast, Atrium Maquet, Hudson NH) is preferred for short segments. It is critical that the proximal intra-aortic end of the chimney stent be positioned >10 mm proximal to the proximal-most fabric edge of the aortic stent graft to ensure optimal intake of blood flow into the LSA branch. While balloon-expandable stents are preferred for the LSA, a self-expanding device may at times need to be used mainly for large-diameter LSA vessels or when the chimney is designed to traverse several cm within the aorta (Fig. 35.1i). In such case, it is advisable to add implantation of a short balloon-expandable bare-metal stent within the conduit, placed across the origin of the LSA to protect it and prevent collapse of the crushing- prone selfexpanding device (Fig. 35.1j). Parallel grafts can also be deployed in a retrograde or periscope configuration (Fig. 35.2). The LSA periscope is a relatively new and appealing addition to our armamentarium as it avoids interfering with the proximal seal zone altogether. For these cases, a Viabahn stent graft (Gore, Flagstaff, AZ) is preferred because of its flexibility and wide range of diameters and lengths. Transfemoral access with delivery of long sheath into LSA is depicted in Fig. 35.2a, while the thoracic aortic stent-graft is positioned for deployment in zone 2. A long Viabahn device is delivered through the sheath, which is then retracted, allowing deployment of the covered conduit (Fig. 35.2c). Deploying the Viabahn (tip to hub) has to be done slowly and carefully to avoid pulling the stent out of the target vessel, which can happen with forceful and fast deployment. Note in the illustration that more than one stent may be needed to allow adequate length to reach the distal end of the thoracic endograft. In these cases, deployment is started proximally at the LSA and then carried distally to the end of the thoracic stent. Implantation of a second Viabahn device (Fig. 35.2d), overlapping with the first, is often needed to encompass the full extent of the thoracic stent graft in the descending thoracic aorta and to emerge below some 10 20 mm beyond the distal edge of the fabric (Fig. 35.2e). This technique has also been applied using the transfemoral LSA periscope to revascularize the aberrant RSA (arsa) (Fig. 35.2f). It is quite appealing given the suitable anatomical course of the proximal portion of the arsa for targeting from a transfemoral approach.
35 Parallel Stent Graft Techniques to Facilitate Endovascular Repair in the Aortic Arch 545 Fig. 35.1 Technique of parallel stent graft for Zone 2 thoracic endovascular aortic repair. (a) Access is established using trans-brachial percutaneous (inset) or surgical cutdown exposure. (b) Glidewire is exchanged for a 0.035-in. stiff wire for advancement of a thoracic stent graft. (c) The thoracic endograft and LSA chimney stent have been delivered to the target position, and (d) the thoracic device has been deployed. Deployment of LSA chimney-covered stent (e h). Selfexpanding stent is used for larger vessels (i) and should be reinforced with balloon expandable bare metal stent (j). By permission of Mayo Foundation for Medical Education and Research. All rights reserved
546 F.J. Criado Fig. 35.1 (continued) Zone 1 Deployment Proximal landing in arch zone 1 implies coverage of the LSA and LCCA (Fig. 35.3a, inset). The latter must be preserved or revascularized in most if not all such cases. While I have personally most often accessed the left carotid via (retrograde) percutaneous puncture in the left neck, many would prefer to do so using a small-incision cutdown operative technique, in which case preliminary placement of a pursestring suture in its anterior wall would make sense for easy tying and hemostasis after sheath removal. Others might prefer to simply clamp or finger-pinch the vessel for a short time while suturing the hole shut. Access is established both in the LCCA and LSA, which are to be preserved with chimney conduits (Fig. 35.3b). For the LSA, a similar setup is used which has been described
Fig. 35.2 (a) The LSA periscope is performed using transfemoral access with delivery of long sheath into LSA. (b) After deployment of the thoracic stent, (c) a Viabahn is deployed. (d) Implantation of a second Viabahn device is often needed to encompass the full extent of the thoracic stent graft. (e) The stent 10 20 mm beyond the distal edge of the fabric. (f) Transfemoral LSA periscope technique to revascularize the aberrant RSA (arsa). By permission of Mayo Foundation for Medical Education and Research. All rights reserved
548 F.J. Criado Fig. 35.2 (continued)
35 Parallel Stent Graft Techniques to Facilitate Endovascular Repair in the Aortic Arch 549 Fig. 35.3 (a) Access via left carotid artery (retrograde) using percutaneous puncture or small incision. (b) Thoracic stent and sheaths in both LCCA and LSA. (c) Thoracic stent is deployed in Zone 1. (d) The LCCA and LSA stents are exposed for deployment. (e) Preservation of the LCCA with placement of a transcervical icast conduit, vascular plug closure of the proximal LSA, and a surgical left carotid-subclavian bypass. (f) LSA is not revascularized, and vessel closure is deemed unnecessary because the aortic endograft occludes its origin from within the aorta. (g) Cervical bypass revascularization of the LSA using carotid-axillary bypass. By permission of Mayo Foundation for Medical Education and Research. All rights reserved
550 F.J. Criado Fig. 35.3 (continued)
35 Parallel Stent Graft Techniques to Facilitate Endovascular Repair in the Aortic Arch 551 in Fig. 35.1 for chimney technique in Zone 2 with the addition of a stiff guidewire and sheath introduced in the LCCA and positioned within the distal ascending aorta. The thoracic endograft is delivered to the arch for deployment in Zone 1. The thoracic stent graft is deployed first, covering the origins of both vessels (Fig. 35.3c). Note technical steps followed for deployment of chimney conduits into both the LSA and LCCA. The sheaths are carefully retracted exposing the chimney stents in both vessels. A Viabahn device is chosen for the longer LSA conduit, and an icast balloon- expandable covered stent for the LCCA (Fig. 35.3d). Worth noting are the intra-aortic proximal ends both lying several mm proximal to the proximal edge of the main endograft. Variations of this technique can be used to decrease the number of chimney grafts and potentially the risk of gutter endoleaks associated with double chimney grafts (Fig. 35.3e). A slightly different strategy consists of preserving the LCCA with placement of a transcervical icast conduit, while the proximal LSA is excluded using a vascular plug closure, and a surgical left carotid-subclavian bypass is performed to preserve flow (Fig. 35.3e). The inset shows yet another variation where the covered LSA is not revascularized and vessel closure deemed unnecessary because the aortic endograft is expected to completely occlude its origin from within the aorta. The author s choice for cervical bypass revascularization of the LSA is illustrated in Fig. 35.3g. In these cases, a left carotid-axillary bypass is performed using two incisions to expose the LCCA in the left neck and the axillary artery via small infraclavicular incision. An 8-mm ringed vascular graft is tunneled under the clavicle and anastomosed end to side to the axillary artery. Axillary-artery exposure, instead of the subclavian artery, is felt to be technically easier and essentially free of potential nerve and lymphatic complications. In suitable anatomies, a right trans-brachial or transaxillary approach may be considered for deployment of the LCCA chimney (Fig. 35.4). Zone 0 Deployment Even more controversial than the rest are chimney solutions for extra-thoracic total arch debranching through a hybrid combination of surgical maneuvers in the neck and placement of a PG conduit into the innominate artery (IA, brachiocephalic trunk). The technical strategy is largely based on the use of the RCCA as access site for IA chimney delivery and deployment and as the origin for a surgical crossover bypass to the LCCA and to the LSA (if desired). Care must be exercised to sequence the various steps in the best possible way to minimize or avoid cerebral ischemia. Fig. 35.4 A right trans-brachial or trans-axillary approach may be considered for deployment of the LCCA chimney. By permission of Mayo Foundation for Medical Education and Research. All rights reserved First, construction of the crossover carotid-carotid bypass, plus a left carotid-subclavian (or carotid-axillary) bypass, is performed as discussed in Chap. 36 (Fig. 35.5a). Retrograde access into the IA is established using a puncture of the surgically exposed RCCA at a point below the graft anastomosis, followed by advancement of guidewire into the ascending aorta and insertion of a suitable (14 16F) introducer sheath through which one can deliver the PG conduit. In these cases, the IA may be of larger diameter (14 18 mm), which often requires the use of an iliac limb of an EVAR graft system. The thoracic stent graft is positioned for deployment in Zone 0. After the thoracic stent is deployed (Fig. 35.5b), it is probably best to complete deployment of the IA device and to surgically repair the arteriotomy site in the RCCA to reestablish normal antegrade flow (Fig. 35.5c), followed by a separate needle puncture to regain guidewire access into the conduit which will be necessary for subsequent post- ballooning to be done after deployment of the aortic endograft. It is wise to position precisely the constrained aortic endograft in the target Zone 0 for landing and in its relation to the IA chimney in its sheath before deploying the chimney device to ensure optimal final placement of the two as shown in Fig. 35.5c. Alternatively, one could choose to deploy the
Fig. 35.5 (a) Surgical crossover bypass to the LCCA and to the LSA. (b) Deployment of the IA stent is completed. (c) The RCCA puncture is surgically repaired to reestablish normal antegrade flow immediately. By permission of Mayo Foundation for Medical Education and Research. All rights reserved
35 Parallel Stent Graft Techniques to Facilitate Endovascular Repair in the Aortic Arch 553 Fig. 35.6 A right axillary artery access conduit can also be used for delivery and deployment of the IA chimney. By permission of Mayo Foundation for Medical Education and Research. All rights reserved aortic endograft first and then quickly proceed to IA chimney deployment and reestablishment of normal blood flow in the RCCA using a small partial occlusion clamp to control the arteriotomy site if necessary. But such strategy is definitely more risky and haste inducing because of the danger of prolonged cerebral ischemia. Lastly, the proximal LSA can be closed (if deemed necessary) with a vascular plug delivered through a left trans-brachial approach. A modification of this technique is depicted in Fig. 35.6. A right axillary artery access conduit can also be used for delivery and deployment of the IA chimney. Conclusion Parallel stent graft techniques have emerged as a reasonable alternative in patients with complex aneurysms who need extension of proximal landing zones across critical aortic branches. The technique has been widely applied in the aortic arch, pararenal, and iliac arteries. References 1. Greenberg RK, Clair D, Srivastava S, Bhandari G, Turc A, Hampton J, et al. Should patients with challenging anatomy be offered endovascular aneurysm repair? J Vasc Surg. 2003;38:990 6. 2. Criado FJ, Barnatan MF, Rizk Y, Clark NS, Wang CF. Technical strategies to expand stent-graft applicability in the aortic arch and proximal descending thoracic aorta. J Endovasc Ther. 2002;9(suppl II):II-32 II-38. 3. Ohrlander T, Sonesson B, Ivancev K, Resch T, Dias N, Malina M. The chimney graft: a technique for preserving or rescuing aortic arch branch vessels in stent-graft sealing zones. J Endovasc Ther. 2008;15:427 32. 4. Mangialardi N, Serrao E, Kasemi H, Alberti V, Fazzini S, Ronchey S. Chimney technique for aortic arch pathologies: an 11-year single- center experience. J Endovasc Ther. 2014;21:312 23. 5. Criado FJ. A percutaneous technique for preservation of arch branch patency during thoracic endovascular aortic repair (TEVAR): retrograde catheterization and stenting. J Endovasc Ther. 2007;14:54 8. 6. Criado FJ. Chimney grafts and bare stents: aortic branch preservation revisited. J Endovasc Ther. 2007;14:823 4. 7. Donas KP, Torsello G, Bisdas T, Osada N, Schönefeld E, Pitoulias GA. Early outcomes for fenestrated and chimney endografts in the
554 treatment of pararenal aortic pathologies are not significantly different: a systematic review with pooled data analysis. J Endovasc Ther. 2012;19:723 8. 8. Criado FJ, Duson S. Parallel grafts in perspective: definitions and a new classification. Vasc Dis Manag. 2013;10:16 9. 9. Lachat M, Veith FJ, Pecoraro F, Glenck M, Bettex D, Mayer D, et al. Chimney and periscope grafts observed over 2 years after their use to revascularize 169 renovisceral branches in 77 patients with complex aortic aneurysms. J Endovasc Ther. 2013; 20:597 605. 10. Scali S, Feezor RJ, Chang CK, Waterman AL, Berceli SA, Huber TS, et al. Critical analysis of results after chimney endovascular F.J. Criado aortic aneurysm repair raises cause for concern. J Vasc Surg. 2014;60:865 73. 11. Hogendoorn W, Schlosser FJV, Moll FL, Sumpio BE, Muhs BE. Thoracic endovascular aortic repair with the chimney graft technique. J Vasc Surg. 2013;58:502 11. 12. Gehringhoff B, Torsello G, Pitoulias GA, Austermann M, Donas KP. Use of chimney grafts in aortic arch pathologies involving the supra-aortic branches. J Endovasc Ther. 2011;18:650 5. 13. Donas KP, Lee JT, Lachat M, Torsello G, Veith FJ, PERICLES investigators. Collected world experience about the performance of the snorkel/chimney endovascular technique in the treatment of complex aortic pathologies. Ann Surg. 2015;262:546 53.
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