| | Branched iliac bifurcation: 6 years experience with endovascular preservation of internal iliac artery flowReceived 11 February 2007; accepted 3 April 2007. published online 30 June 2007. ObjectiveThe objective of the current study was to share a 6-year experience with the iliac bifurcation device (IBD) and determine its safety and effectiveness in patients with common iliac artery aneurysms. MethodsBetween 2001 and 2006, 46 patients were prospectively enrolled in a single institution study on the IBD. Indications included unilateral or bilateral common iliac artery aneurysms (CIAA) (combined or not with abdominal aortic aneurysm endovascular repair). The first 26 patients were intended to receive a first generation unibody IBD and the following 20 patients the second generation, modular, IBD. ResultsIn 33 patients out of 46 attempted (technical success per patient 72%), 35 iliac bifurcated devices (2 patients received bilateral IBD) out of 51 attempted (technical success per vessel 69%), were successfully implanted. The technical success rate (per vessel) was 58% for the first generation device and 85% for the second generation device. Inability to introduce the side branch into the IIA and intraoperative occlusions were the main reasons for technical failure. Among these failures, only two patients required open conversions. The mean ± SD follow-up (radiological and clinical) of the 33 patients with a total of 35 successful IBD implantations was 26 ± 17 months (median 24, range 3 to 60). During the follow-up period out of 35 successfully-implanted iliac bifurcation devices, four (11%) hypogastric side branch occlusions occurred, all within the first 12 months. Cumulative IBD side branch patency was 87% at 60 months. Comparing the first with the second generation IBD outcomes, cumulative patency rates at 2 years revealed no statistical difference (P = .774). No endoleak, and particularly no IBD, modular side branch disconnection, no late rupture, or deaths have yet been encountered. ConclusionsPreservation of pelvic circulation in high risk patients treated for bilateral or unilateral common iliac aneurysms combined or without AAA is feasible and secure exclusively by endovascular repair. New generation iliac bifurcated devices show a favourable intraoperative performance and long-term outcomes. Endovascular abdominal aortic aneurysm (AAA) repair (EVAR) has reached its maturity. As experience and knowledge on EVAR technology and device behavior expand, an even broader range of patients with more complicated anatomies are targeted in order to be eligible for this minimal invasive technique. Combined aortic and common iliac artery aneurysms (CIAA), encountered in 20% to 30% of cases 1, 2 always posed a barrier for a solitary and uneventful EVAR procedure. It is nowadays clear that secure distal fixation of a bifurcated endograft requires an adequate long segment of undilated iliac artery.3 Small CIAA (18 to 24 mm) might often be treated by the “bell bottom” technique, a questionable concept, since in longer follow-up, further vessel dilatation and/or distal leak due to retrograde migration usually emerge, necessitating some kind of secondary intervention. According to our experience, when iliac diameter exceeds 24 mm safe endograft landing proximal to the internal iliac artery (IIA) is impossible. The challenge is even higher when bilateral CIAA are involved and the concerns of severe pelvic ischemia are profound.4, 5 Traditionally, extension of the endograft’s iliac leg to the external iliac artery has been used, excluding the hypogastric artery, occasionally accompanied by coil embolization.6 Measures to preserve internal iliac flow such as aortouniiliac endografts, external to internal iliac endografts and IIA revascularization techniques followed by femoro-femoral bypass have been adopted.6, 7, 8, 9, 10 Clinically, an IIA unilateral occlusion may range from asymptomatic occlusion to the development of buttock claudication and impotence and less frequently of colon and spinal ischemia, all symptoms summing up to 12% to 45%.11, 12, 13, 14 Bilateral interruption antegrade IIA flow is rarely asymptomatic and ischemic complications can result in severe morbidity and mortality.12, 13, 14Since branched endograft devices are already used successfully, modular iliac bifurcated devices (IBD) are an appealing alternative to avoid IIA occlusions or complicated surgical procedures.15, 16, 17 The objective of the current study was to share our 6-year experience and particularly our learning curve with the IBD and determine its safety and effectiveness (combined or not with AAA endovascular repair) in patients with common iliac artery aneurysms. Patients and methods  Between February 2001 and September 2006, 46 patients underwent elective endovascular repair of aortoiliac or solitary CIAA using the IBD at the Surgical Department of Städtische Kliniken Frankfurt-Höchst, Germany. All patients fulfilled standard accepted indications for EVAR. Our first 26 patients were selected to receive a first generation unibody IBD (William Cook Inc, Brisbane, Australia) (group 1), while 20 patients received the second generation, modular, IBD (William Cook Inc, Brisbane, Australia) (group 2). Patient and aneurysm characteristics are presented in Table I. Device description First generation iliac bifurcation device The first generation unibody IBD was a two-branch stent graft consisting of common (12 mm diameter, 45 mm length), external (10 mm diameter, 37 mm length), and internal iliac segments (12 mm distal diameter, 29 mm length) The internal segment was planned to be introduced into the IIA (Fig 1, A). An preloaded catheter passed through the external into the common segment from where it curves back into the internal segment like a shepherd-hook catheter. Its metallic rounded tip formed the tip of the constricted internal branch. Second generation iliac bifurcation device The new generation, modular, IBD is a two-branch vessel graft consisting of the common (12 mm diameter, 44 mm length), the external (10, 12, or 14 mm diameter, 54 or 71 mm length), and the reinforced stump (8 mm diameter, 12 mm length) for the hypogastric side branch (Fig 1, B). The graft is preloaded, with proximal and distal fixation, onto an introducer sheath. A preloaded catheter passes through the introducer, outside of the external iliac segment, enters the graft through the distal opening of the side branch and exits the graft through the proximal end of the common iliac segment. Two release strings on the handle are controlling proximal and distal attachment. Iliac bifurcation device implantation technique Treatment of solitary iliac aneurysms included the deployment of the Zenith Composite (William A. Cook) bifurcated component accommodated on the aortic bifurcation as previously described.18 Aortic aneurysms were excluded with standard bifurcated Zenith devices (four trifab, 26 composite, two fenestrated composite). The bifurcated aortic components can be introduced through either side. In bilateral common iliac aneurysms, unless two IBD were successfully implanted, bell bottom iliac limb, bypass, or intentional occlusions of the contralateral IIA were carried out. Successful implantation of an IBD is defined as iliac bifurcation graft and internal iliac side branch patency, without type I or III leak by the end of the endovascular procedure. First generation unibody iliac bifurcation device An angiogram was performed perpendicular to the iliac bifurcation angle as taken from the computed tomography (CT) and the offspring of the internal iliac artery is marked. The IBD was prepared as for a standard Zenith procedure and, with the aid of the gold radiopaque markers, was advanced over a guide wire until the side branch was just proximal to the origin of the internal iliac artery. The delivery sheath of the proximal part was withdrawn, including the side branch, which remained constricted over the indwelling catheter. The IIA was then cannulated with a wire passing through the preloaded catheter and by pulling back the device, its side branch slipped and cannulated into the IIA. The side branch was opened by removing the restriction wire. An angiography confirmed satisfactory position. Zenith endograft deployment for the AAA followed. Second generation modular device An angiogram was performed as described above. The IBD was prepared for a standard Zenith procedure and, with the aid of the gold radiopaque markers, was advanced over a guide wire until the side branch was just proximal to the origin of the internal iliac artery. Following withdrawal of the delivery sheath until the distal end of the side branch was exposed, a thin wire through the indwelling catheter was advanced into the aorta and was extracted through the contralateral side using a snare catheter (Entrio Snare; Bard, Olen, Belgium). An 8F cross-over-sheath (Balkin’up & Over Contralateral Flexor Introducer Sheath; William Cook, Bjaeverskov, Denmark) was passed from the contralateral groin over the thin through-and-through wire into the proximal opening of the device and the stump for the side branch. Alternatively, the thin wire of the preloaded catheter could be snared through the longer brachial access. Through the cross-over sheath, the hypogastric artery was cannulated with a regular 0.035-inch Terumo guidewire (Terumo Europe N.V., Leuven, Belgium) and after removal of the thin wire the sheath was further advanced into the hypogastric artery using a partially inflated low diameter (4 to 5 mm) balloon catheter. The selected extension stent-graft was advanced into the internal iliac artery and after withdrawal of the cross-over sheath deployed. An angiography through the cross-over sheath confirmed satisfactory position of the side branch (Fig 2). Zenith endograft deployment for the AAA followed. Follow-up The patients’ follow-up was comprised of computed tomography aortography (CTA) and plain x-rays, either at discharge or within 6 months of EVAR, followed by 12 month scans and yearly ones, thereafter. Each CTA was carefully assessed for component position, endoleaks, migration, and sac status. Clinical examination and laboratory studies, including serum creatinine concentration and blood urea nitrogen, were also assessed on a regular basis. Statistical analysis Values are presented as as means ± standard deviation and ranges or as frequency and percentage. Subgroup univariate comparisons were assessed with the χ2 test and Fisher exact test to identify variables potentially associated to IBD technical failure or delayed occlusion. Statistical significance was assessed with P < .05. Late outcomes were assessed using Kaplan-Meier life-table analysis and the log-rank test was used when comparing subgroups. Results Operative results In successful IBD implantations, mean operating time was 183 ± 52 minutes (range 100 to 330), mean x-ray time 23.5 ± 14.8 minutes (range 6 to 68), and mean contrast media used 85 ± 35 ml (range 33 to 180). All values refer to the whole operative procedure, including bilateral IBD implantations and AAA repair (24 out of 33 cases), when existing. Comparing the values with the relative ones of our >1200 patient EVAR cohort, the mean operating time was 59 minutes more, the mean x-ray time 8.5 minutes more, and the mean contrast media 15 ml more. Blood transfusion was necessary for three patients. Success rates, technical failures and intraoperative complications In 46 patients, 51 total IBDs (five bilateral attempts), IBDs were scheduled to be implanted. It finally succeeded (at least one IBD implanted successfully) in 33 patients (technical success per patient 72%) by implanting 35 IBDs (two successful bilateral implantations). The technical success per vessel was 69% (35 successful/51 attempted) (Fig 3). By splitting the success rates between the two devices, the technical success rate per patient for the first generation device (group 1) was 62% and for the second generation device (group 2) 85%. The technical success rate per vessel was 58% for group 1 and 85% for group 2 (Table II). Primary failures to implant an IBD were 13 out of 31 (attempted vessels) for group 1 and 3 out of 20 (attempted vessels) for group 2. Reasons for primary failure per device are illustrated in Table III. Inability to introduce the side branch into the IIA, usually associated to ostial stenosis, and intraoperative occlusions, usually associated to IBD misplacement, were the main reasons for technical failure. Univariate comparisons demonstrated severe kinking as a significant factor of IBD acute breakdown (P = .019, odds ratio [OR] = 4.3). | | |  | | First generation IBD | Second generation IBD | |
|---|
| Device failure | 2 | 0 | | | Intubation failure | 8 | 0 | | | Intraoperative occlusion following successful IBD implantation | 3 | 2 | | | Side branch deployment failure | — | 1 | | | Total | 13 | 3 | | | | |
In 14 out of 16 target vessels (in 13 patients) with a primary failure, a limb graft extension to the external iliac artery was carried out sealing the offspring of the IIA or of the IBD side branch. No retrograde leaks were noted during the follow-up. The remaining two patients (two vessels), both due to device deployment failure, were converted to open repair, IBD explantation, and conventional aortobiiliac reconstruction. Loss of both IIAs occurred in two patients. These were primary failures combined with the pre-planned intentional occlusions of the contralateral IIA. They only suffered from intermittent buttock claudication, which gradually subsided within the first postoperative month. One intraoperative occlusion of the side-branched IIA was successfully treated by local thrombolysis and percutaneous angioplasty (PTA). One other showed recanalization of the IIA on the control angiography on the second postoperative day. Though unusual, we assume that recanalization occurred due to spontaneous lysis of an otherwise fresh clot, following adequate flow re-establishment after an impaired intraoperative (eg, due to wire and sheath manipulations) circulation in the IIA. Two years later, both IIAs are patent. One intraoperative occlusion of the AAA graft limb, in a patient who received successfully bilateral IBD, was managed with a fem-fem bypass and the patency of both internal arteries remained unaltered. Perioperative results (<30 days) Almost all patients, postoperatively, were routinely transferred to the Intensive Care Unit (ICU) or to a high dependency ward up to the next morning. Mean ± SD postoperative hospital stay was 5.8 ± 7.3 days (median 4, range 2 to 44). One patient, who intraoperatively experienced subarachnoidal bleeding, required a 44-day long hospital stay but was completely recovered when discharged. No patient died during or after the operation. Follow-up and IBD patency The mean ± SD follow-up of the 33 patients with a total of 35 primary successful IBD implantations was 26 ± 17 months (median 24, range 3 to 60). So far there was no readmission for IBD secondary intervention. However, in one patient, initially treated for bilateral CIAAs and large bilateral IIA aneurysms, the growing aneurysmal IIA contralateral to the IBD had to be excluded by open technique 1 year later. During the further follow-up the diameter of the IIA aneurysm, ipsilateral to the IBD, similarly grew (from baseline diameter 50 mm to 65 mm), leading the fixed side branch to slip out of the hypogastric ostium, without though certain signs of IBD migration. The IIA remains patent, and no secondary procedure was scheduled due to the patient’s poor condition and the risk of compromising further the IIA blood flow. During the follow-up period, four out of 35 (11.4%) successfully implanted IBDs (in four different patients) showed side branch occlusions, all within the first 12 months. Among the 35 successful implantations, cumulative IBD patency was 87.3% at 60 months (Fig 4). When comparing the first with the second generation IBD outcomes, concerning 2-year cumulative patency (88.9% and 83%, respectively), no statistical difference was revealed (Log-rank test P = .774) (Fig 5). The potential reasons for the four occlusions could be determined only in two cases: in one it was severe kinking of the fixed hypogastric side branch causing stenosis and flow reduction and in the other a severely kinked CIA caused distal migration of the IBD, which led to occlusion of the side branch. The other two cases showed no detectable changes of the graft configuration or any mechanical explanation for the occlusion. Univariate comparisons did not demonstrate any significant factor for IBD occlusion. Among these patients only one suffers from nondisabling buttock claudication. Gradual shrinkage, >5 mm, of CIAA treated successfully with an IBD was evident in 16 out of 25, which have reached the 12-month follow-up, in 18 out of 19 CIAA, which have reached the 24-month follow-up, and in all 11 cases, which have reached the 3-year follow-up. A decrease in AAA sac size >5 mm was evident in 14 out of 20 patients in the 12-month follow-up and in 15 out of 17 patients in the 24-month follow-up. The sizes in both CIAA and AAA have not increased in any of our patients. No endoleak, and particularly no IBD, modular side branch disconnection, no late rupture, or deaths have yet been encountered. Discussion As EVAR gradually takes over conventional surgical repair in high risk patients, contraindication barriers are progressively demolished. Fenestrated and branched endografts have already shifted the proximal sealing zone from the infrarenal to the suprarenal aortic segment rendering feasible the endovascular repair of juxta-, para-, and suprarenal aneurysms. The present study supports the use of iliac bifurcated devices, in selected patients with aneurysmal common iliac arteries, unsuitable for distal sealing with a standard endograft. Maintaining antegrade perfusion of at least one IIA during endovascular aortoiliac aneurysm repair has been advocated as ultimately essential to safeguard pelvic perfusion4, 5 and experience has shown that symptoms of pelvic ischemia are not generally predictable and persist in the majority of patients over many years, despite active exercise. The technical success rates of the first generation IBD were disappointingly low (58%) related to the learning curve, to the arbitrary patient selection, and to the concept of a unibody device. During our early experience, implantation difficulties and risk of failure were increased by: (1) narrow lumen of the CIA due to thrombus, (2) severe kinking of the external iliac artery, (3) narrow (stenotic) internal iliac ostium, and (4) wide angle (>50°) of the IIA offspring. Internal iliac artery intubation difficulties met with the old device concept are not any more an issue. By better patient/anatomy selection and improved technical skills, along with the modular concept of the second generation device, success rates substantially improved reaching 85%. Similar success rates are reported in two other series by Greenberg et al16 (21 patients, 86% technical success rate) and by Malina et al17 (10 patients, 90% technical success rate). The most challenging part of the implantation of the modular device, currently, seems to be the cross-over deployment of the IIA stent-graft. The current availability, though, of improved and longer sheaths allows transbrachial access, to overcome cross-over deployment difficulties. In secondary IBD implantations, where cross over is extremely difficult, transbrachial access appears to be superior, despite the low risk of stroke. The long-term outcomes promise a thriving future for the iliac bifurcation devices. According to the Kaplan Meier estimations, no matter which device was used (first or second generation) after successful implantation, cumulative graft patency was not significantly different between the two devices. Notably, after the 12-month period (20 cases), no side branch occlusions occurred. So, the overall estimated 60 month patency reaches approximately 88%. Reasons for our four postoperative IBD side branch occlusions could be determined only in two cases and were attributed to severe kinking of the CIA or the IIA. We have to assume that the occlusion in the other two cases was caused by local thrombosis due to flow or coagulation factors, as time for developing intimal hyperplasia19 seems too short. So far, no ruptures or complications needing a secondary intervention have been encountered. Our experience provides an initial benchmark for all users of branched devices. Iliac bifurcation device implantation might be challenging, and the reported favorable outcomes are dependent on training in the technique and patient selection. The need for careful patient selection with favorable anatomy (no extreme iliac kinking, efficient thrombus-free iliac lumen, sufficiently open IIA ostium, and no large IIA aneurysm), meticulous planning, and expert catheterization skills are of utmost importance. Future device modifications directed towards longer inter-stent gaps of the IBD main body will allow improved adoption to iliac kinking while the availability of more flexible self-expanding low profile stent grafts as modular hypogastric side branches could also improve technical success and long-term outcomes. Conclusions Preservation of pelvic circulation in patients treated for common iliac aneurysms, without or combined with AAA, is feasible and secure by an exclusive endovascular repair. New generation iliac bifurcated devices show a favorable intraoperative performance and good long-term outcomes, outweighing their higher costs. The superiority of this demanding endovascular procedure against the complex conventional alternatives will be established as soon as new long-term series provide equally encouraging results. Author contributions Conception and design: PZ, EA, WS Analysis and interpretation: PZ, EA, TU, TP, KE, WS Data collection: EA, KE Writing the article: PZ, EA Critical revision of the article: PZ, TU, TP, WS Final approval of the article: PZ, EA, TU, TP, KE, WS Statistical analysis: EA Obtained funding: Not applicable Overall responsibility: WS References 1. 1Armon MP, Wenham PW, Whitaker SC, Gregson RH, Hopkinson BR. Common iliac artery aneurysms in patients with abdominal aortic aneurysm. Eur J Vasc Endovasc Surg. 1998;15:255–257. Abstract |
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14. 14Yano OJ, Morrissey N, Eisen L, Faries PL, Soundararajan K, Wan S, et al. Intentional internal iliac artery occlusion to facilitate endovascular repair of aortoiliac aneurysms. J Vasc Surg. 2001;34:204–211. Abstract | Full Text |
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17. 17Malina M, Dirven M, Sonesson B, Resch T, Dias N, Ivancev K. Feasibility of a branched stent-graft in common iliac artery aneurysms. J Endovasc Ther. 2006;13:496–500. MEDLINE |
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18. 18Stelter WJ. Use of aortic bifurcation for better graft stability: a new generation concept. XV International Congress on Endovascular Interventions, Phoenix, Arizona, USA, Feb 2002, Abstract IV-2. 19. 19Halak M, Goodman MA, Baker SR. The fate of target visceral vessels after fenestrated aortic repair – general considerations and mid-term results. Eur J Vasc Endovasc Surg. 2006;32:124–128. Abstract | Full Text |
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Städtische Kliniken, Frankfurt a.M. Höchst, Frankfurt, Germany.  Reprint requests: Peter Ziegler, MD, Consultant Surgeon and Vascular Surgeon, Städtische Kliniken Frankfurt a.M.-Höchst, Chirurgische Klinik, Gotenstrasse 6, 65929 Frankfurt, Germany
Competition of interest: none. PII: S0741-5214(07)00581-2 doi:10.1016/j.jvs.2007.04.015 © 2007 The Society for Vascular Surgery. Published by Elsevier Inc. All rights reserved. | |
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