Branched Grafts for Thoracoabdominal Aneurysms: Off-Label Use of FDA-Approved Devices

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1 471 TECHNICAL NOTE Branched Grafts for Thoracoabdominal Aneurysms: Off-Label Use of FDA-Approved Devices Karthik, MD Emory University School of Medicine, Atlanta, Georgia, USA. Purpose: To report off-label use of approved off-the-shelf endografts with no modification to the devices for the management of thoracoabdominal aneurysms (TAAA). Technique: The parallel endograft octopus technique is demonstrated in a 68-year-old woman with a past history of open TAAA repair with a patch reimplant of the visceral vessels who now presented with back pain. Non-contrast computed tomography revealed a 6.8-cm aneurysm of the visceral segment involving the celiac trunk, superior mesenteric artery (SMA), and right renal artery. As she was at high risk for redo surgery due to significant pulmonary dysfunction, she was an ideal candidate for a branched graft, but she could not travel to an investigational site for a custom graft. At surgery, 4 sheaths were introduced, 2 retrograde (18-F DrySeal) and 2 (8-F) antegrade, via the femoral arteries. The 18-F sheaths on both sides were connected to the 8-F sheaths for continued limb perfusion. Via an axillary conduit, a 12-F, 80-cm sheath was introduced into the proximal thoracic aorta over a stiff wire. Subsequently, two 28-mm Excluder endografts were introduced via the bilateral 18-F femoral sheaths and positioned side by side in the descending thoracic aorta such that the lower end of the Excluder limbs were positioned $2 cm above the target visceral vessels. Viabahn stent-grafts were then deployed in the celiac axis, SMA, and right renal artery from the axillary conduit. Subsequently, a 23-mm Excluder was deployed within the distal end of the upsized limb and extended to both common iliac arteries. Imaging at 6 months demonstrated no endoleaks, with good flow to all visceral vessels. Conclusion: The parallel endograft octopus technique described here, which has been applied successfully in 9 cases thus far, is a relatively simple method using currently available devices with no requirement for device modification or customization. Although this technique shows promise, long-term data will be required to prove efficacy. This technique demonstrates a concept for future development of branched graft technology. J Endovasc Ther. Key words: thoracoabdominal aortic aneurysm, visceral aneurysm, endovascular repair, stent-graft, off-label use, branched graft, parallel endograft octopus technique Off-the-shelf branched grafts can be viewed as the holy grail of endovascular therapy for thoracoabdominal aneurysms (TAAA). Currently, no branched grafts are available in the US, where use of these customized devices is restricted to investigational sites. However, a parallel endograft octopus technique has been developed to use off-the-shelf approved endografts for TAAA repair with no modification to the devices. TECHNIQUE This novel technique is demonstrated in a 68- year-old woman who presented with complaints of back pain. Past surgical history The author has no commercial, proprietary, or financial interest in any products or companies described in this article. Address for correspondence and reprints: Karthik, MD, Department of Surgery, Emory University Hospital, Room H-122A, 1364 Clifton Rd. NE, Atlanta, GA USA. kkasira@emory.edu ß 2011 by the INTERNATIONAL SOCIETY OF ENDOVASCULAR SPECIALISTS Available at

2 472 BRANCHED GRAFTS FOR TAAA Figure 1 (A,B) CT scans demonstrating a 6.8-cm aneurysm of a prior visceral patch implant. Note absence of the left kidney. (C) Continued limb perfusion via male to male adaptors (noted by forceps) to minimize the effect of ischemia reperfusion to the limbs. (D) Initial diagnostic angiogram of the aneurysm. involved an open juxtarenal aneurysm repair 11 years prior, with a subsequent left nephrectomy for renal infarction. Two years later she underwent an open thoracoabdominal repair with a patch reimplant of the remaining 3 visceral vessels. During the current workup for back pain, non-contrast computed tomography (CT) revealed a 6.8-cm aneurysm of the visceral segment involving the celiac, superior mesenteric artery (SMA), and right renal artery (Fig. 1A,B). She was considered at high risk for redo surgical thoracoabdominal repair or visceral debranching techniques due to significant pulmonary dysfunction (forced expiratory volume 0.9 L in 1 second). Based on the aneurysm morphology, the patient was considered an ideal candidate for a branched graft, but given the symptomatic nature of her aneurysm, it was felt that she would not be able to travel to an investigational site for a custom branched graft. Therefore, an endovascular technique using off-the-shelf endografts was devised after appropriate patient consent for off-label device use. Retrospective chart review was performed for patient/procedural details (IRB# ). At surgery, the patient was placed under general anesthesia, and both femoral arteries were exposed through transverse incisions. The left axillary artery was also exposed, and after adequate heparinization, a 6-mm Dacron

3 BRANCHED GRAFTS FOR TAAA 473 Figure 2 (A) Drawing and (B) fluoroscopic image of the 2 parallel Excluder devices deployed in the descending thoracic aorta. Note the left axillary conduit in A. (C) Drawing and (D) angiogram of the branched graft to the celiac artery. conduit was sewn to the left axillary artery. Two 18-F DrySeal sheaths (W.L. Gore & Associates, Flagstaff, AZ, USA) were introduced retrograde into the common femoral arteries; 2 additional 8-F sheaths were introduced antegrade in both distal common femoral arteries. To minimize the ischemia-reperfusion phenomenon after prolonged limb ischemia, the 18-F sheaths on both sides were connected to the 8-F sheaths via male-to-male adaptors to allow continued limb perfusion (Fig. 1C). A 12-F, 80-cm sheath was introduced via the axillary conduit into the proximal thoracic aorta over a stiff wire. Subsequently, two 28-mm proximal diameter Excluder endografts (W.L. Gore & Associates) Figure 3 (A) Superior mesenteric artery cannulation from above; note the minimal angulation of approach allowing for easy cannulation. (B) Celiac and superior mesenteric artery branch grafts via the short gate of the Excluder endograft. (C) Drawing and (D) completion angiogram after right renal branch graft; note the 10-mm Excluder limb used to downsize prior to renal artery cannulation. were introduced via the bilateral 18-F femoral sheaths (prior descending thoracic aortic graft diameter was 34 mm). Based on the initial angiogram (Fig. 1D), the grafts were positioned side by side in the descending thoracic aorta (Fig. 2A,B) such that the lower end of the Excluder limbs were positioned to be at least 2cmormoreabovethetargetvisceralvesselto be cannulated. Following graft deployment, the short gate of one of the Excluder devices was cannulated from the 12-F axillary sheath. A vertebral catheter (Cook Inc, Bloomington, IN, USA) was then used to selectively cannulate the celiac axis, which was confirmed by a subsequent angiogram via the catheter. An mm Viabahn stent-graft (W.L. Gore & Associates) was then deployed in the celiac axis and subsequently extended to the upper end of the short Excluder limb with a mm Viabahn

4 474 BRANCHED GRAFTS FOR TAAA Figure 4 (A) Drawing of the parallel (octopus) endograft technique on completion. (B) Completion angiogram demonstrates no endoleak with good flow to all 3 visceral vessels. (C) CT scan at 6 months showing excellent graft patency and no endoleak. (D) Note the well expanded proximal cuffs with no graft infolding or extra-graft contrast flow. (Fig. 2C). The Viabahn stent-graft was then sequentially dilated distal to proximal with 10- mm and 14-mm angioplasty balloons. Repeat angiography via the 12-F sheath demonstrated good antegrade flow into the celiac axis with no endoleak (Fig. 2D). Subsequently, the second Excluder was cannulated from above, and via the second short gate, the SMA was cannulated (Fig. 3A). Two additional Viabahn devices were deployed to extend proximally to the Excluder limbs from the SMA (distal mm and proximal mm; Fig. 3B). Following celiac and SMA stent-grafting, attention was directed to the right renal artery. At this point, a 10-mm Excluder limb was deployed via the femoral route inside one of the long limbs of the Excluder graft to reduce the diameter of the Excluder limb so that a Viabahn stent-graft sized for the renal artery would be diametrically compatible. The

5 BRANCHED GRAFTS FOR TAAA 475 TABLE Advantages of the Octopus Branched Graft Technique 1. Individual customization is not necessary. 2. Graft limb orientation to visceral vessels is not required. 3. Axillary access provides simplified visceral vessel cannulation. 4. Branch graft flexibility better tolerates moderate graft migration without occlusion/stenosis. 5. Modular graft configuration can provide.3-cm limb overlap to ensure adequate and durable seal. femoral wire was then withdrawn, and the gate was cannulated from above with subsequent cannulation of the right renal artery. An 8310-mm Viabahn and a second mm Viabahn were then extended from the right renal artery to the 10-mm Excluder limb (Fig. 3C,D). The remaining long limb of the Excluder was then upsized with a 20-mm limb from the femoral route. Subsequently, a 23- mm Excluder was deployed within the distal end of the upsized limb and extended to both common iliac arteries in the same fashion as a standard abdominal aortic endograft procedure (Fig. 4A). All graft and attachment site junctions were dilated from above or below to prevent any junctional endoleaks, which were ruled out on the completion angiogram (Fig. 4B). The axillary Dacron graft was stapled close to the anastomotic site, and all other arterial access sites were appropriately closed. Total fluoroscopic time was 98 minutes. The patient was extubated on postoperative day 3 and had no neurological complications. A 6-month CT (Fig. 4C,D) demonstrated no endoleak, with good flow to all visceral vessels. DISCUSSION The standard open surgical management of visceral patch aneurysms carries a high operative mortality, 1,2 which can be mitigated by using hybrid visceral bypass techniques, although these continue to carry high morbidity. 3 Fenestrated stent-grafts would be an option in these cases, but these devices are not yet approved in the US. Moreover, the US trial of fenestrated stent-grafting for juxtarenal abdominal aortic aneurysms (AAA) was halted after enrolling 30 patients due to dismal results involving the renal fenestrations. The 4-year trial results presented early in reported 13 renal events in 12 of the 17 patients who had completed the 4-year follow-up, despite a 9-mm infrarenal neck length and a 32u infrarenal neck angle. 4 This data appears to suggest that fixed fenestrations may not have a durable resultandneedtoberestrictedtoinvestigational sites with Food and Drug Administration (FDA) oversight. A variety of off-label stents are currently used to fix fenestrations with the current technology. The in situ forces experienced by these stents have not been well studied and can have significant implications for the long-term durability of fenestrated grafts. Failure may also be related to the use of balloon-expandable stents in an environment that is not fixed (renal/pulmonary motion). The durability of visceral branch grafts may hinge on device flexibility and kink resistance. The devices used in the case reported here have known kink resistance and the lowest limb occlusion rates in clinical trials. Mobile fenestrations or branches may be a more realistic option for these patients as this technology continues to develop. 5,6 However, no branched graft study is currently underway in the US. The parallel endograft octopus technique described here is a relatively simple method using currently available devices with no requirement for modification or customization (off-the-shelf), which has multiple advantages (Table). Although the technique is easier compared to the need to align fenestrations to the visceral vessels with the current technology, it does require advanced endovascular skills. It is very important to maintain wire access at all times until the Viabahn grafts are reconnected to the Excluder main body to avoid free-floating grafts. Additionally, a minimum of 5-cm graft-tograft overlap is recommended to avoid late type III endoleaks. In the future, devices with multiple limbs (octopus) that can be deployed

6 476 BRANCHED GRAFTS FOR TAAA sequentially with a single proximal cuff may help simplify the thoracic branched graft technology and may, for the first time, allow off-the-shelf branched devices. The author has performed 9 of these procedures thus far with no major stroke or paraplegia; 1 patient had an endoleak of unknown origin on follow-up CT. If 4-vessel branching were required, the second renal artery could be revascularized with a periscope technique (covered stent extending from the iliac artery to one of the renal arteries, parallel to the aortic endograft). This sandwich technique has been described previously by various authors. 7,8 Another technique involves 2 Viabahn grafts deployed inside a single Excluder limb from above to accommodate the fourth visceral vessel if required. Two important additional adjuncts to these procedures involve the use of axillary conduits and continued lower limb perfusion via the 8-F antegrade femoral sheaths. Prolonged endovascular procedures that require bilateral largediameter sheath access can be associated with significant intraoperative lower limb ischemia time. Additionally, upon sheath removal, cardiopulmonary systems can be stressed as effective blood volume is reduced by dramatically increased vasculature capacity and the release of free radicals during the reperfusion phenomenon, which is significant in the many TAAA patients who present with chronic obstructive pulmonary disease. Maintaining blood perfusion to the extremities can possibly reduce this cardiac overload and avoid acute lung injury. Brachial access is best avoided for sheaths larger than 8 French. The axillary conduit allows for free sheath movement, with minimal vascular trauma and continued distal limb perfusion throughout the procedure. Conclusion Although the parallel endograft octopus technique shows promise, long-term data will be required to prove its efficacy. This technique demonstrates a concept for future development of branched graft technology. REFERENCES 1. Lombardi JV, Carpenter JP, Pochettino A, et al. Thoracoabdominal aortic aneurysm repair after prior aortic surgery. J Vasc Surg. 2003;38: Coselli JS, Bozinovski J, LeMaire SA. Open surgical repair of 2286 thoracoabdominal aortic aneurysms. Ann Thorac Surg. 2007;83:S Tshomba Y, Bertoglio L, Marone EM, et al. Visceral aortic patch aneurysm after thoracoabdominal aortic repair: conventional vs. hybrid treatment. J Vasc Surg. 2008;48: Makaroun M. The US multicenter trial of fenestrated endograft repair for juxtarenal AAA. Presented at Controversies and Updates in Vascular Surgery, January 27 29, 2011; Paris, France. 5. Sweet MP, Hiramoto JS, Park KH, et al. A standardized multi-branched thoracoabdominal stent-graft for endovascular aneurysm repair. J Endovasc Ther. 2009;16: Verhoeven EL, Muhs BE, Zeebregts CJ, et al. Fenestrated and branched stent-grafting after previous surgery provides a good alternative to open redo surgery. Eur J Vasc Endovasc Surg. 2007;33: Kolvenbach RR, Yoshida R, Pinter L, et al. Urgent endovascular treatment of thoracoabdominal aneurysms using a sandwich technique and chimney grafts a technical description. Eur J Vasc Endovasc Surg. 2011;41: Lobato AC. Sandwich technique for aortoiliac aneurysms extending to the internal iliac artery or isolated common/internal iliac artery aneurysms: a new endovascular approach to preserve pelvic circulation. J Endovasc Ther. 2011;18: