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Bilateral Internal Iliac Artery Occlusion for EVAR
Abstract
Purpose. Internal iliac artery occlusion can be an intentional or inadvertent complication of endovascular aneurysm repair, especially repair of abdominal aortic aneurysms (EVAR). Several studies have reported on side effects experienced by patients as a result of bilateral internal iliac artery occlusion, with buttock claudication and erectile dysfunction being the most frequent. A low incidence of serious side effects, including colonic and spinal cord ischemia, have been reported. In our study, we add the experience of 7 patients who underwent bilateral internal iliac artery occlusion at our institution in conjunction with endovascular repair of aneurysms of the abdominal aorta or common iliac arteries. Methods. A retrospective chart review was performed on patients who received embolization or experienced inadvertent occlusion of both internal iliac arteries. Patients were also contacted by phone and were asked about their experience with the procedures. Data regarding the incidence and severity of side effects as experienced by patients were compared to that obtained from published studies. Results. Between May 2000 and May 2010, 7 patients underwent procedures resulting in bilateral occlusion of the internal iliac arteries. Four of 7 patients (57%) experienced initial buttock claudication following the procedures; of these, claudication resolved by 18 months in 2 of 4 patients. Two of 7 patients (29%) reported experiencing new-onset impotence following the embolization procedures. There were no incidences of colonic or spinal cord ischemia. Conclusions. Bilateral internal iliac artery occlusion appears to have an acceptable incidence of side effects, with buttock claudication being the most common negative symptom.
VASCULAR DISEASE MANAGEMENT 2011;8(1):E1–E5
Key words: abdominal aortic aneurysm; iliac artery; iliac occlusions; aortic aneurysm stent graft
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Introduction
Endovascular repair of abdominal aortic aneurysms (EVAR) has become a robust alternative to open surgical repair in appropriately selected candidates. Reported lower morbidity, perioperative mortality and decreased duration of hospital stay1–3 have contributed to the increasing use of EVAR when feasible. Common iliac artery (CIA) aneurysms are present unilaterally or bilaterally in approximately 16% and 12% of patients with identified abdominal aortic aneurysms (AAA), respectively4 A potential obstacle to EVAR is distal aneurysms, including those affecting the common iliac artery and its branches. Common iliac or external iliac artery aneurysms may require that an aortic stent-graft be extended distally into the external iliac artery in order to provide adequate distal sealing of the graft. The presence of internal iliac artery (IIA) aneurysms may require occlusion by stent grafting or coiling. Disruption of flow to the IIA can also occur with unintentional traumatic interruption of the artery or distal migration of an aortic stent-graft that covers the IIA orifice. Thus, IIA occlusion can become an intentional or unintended complication of EVAR.
Reported complications of unilateral and bilateral IIA occlusion include buttock and thigh claudication, impotence and other more rare occurrences such as colonic ischemia, spinal cord ischemia and scrotal skin sloughing.5–7 The reported frequency of these side effects vary, but the majority of available data suggest that bilateral IIA occlusion results in increased morbidity as compared to unilateral occlusion.8–11 Rayt et al, in a study consisting of case series data pooled with data derived from 18 previously published studies, reported that the most common adverse effect experienced by patients who underwent bilateral IIA embolization was buttock claudication, occurring with a frequency of 35% (34 of 98 patients).8 In many of these studies, improvement or resolution of claudication was documented in some or most patients after 1, 6 or 12 months. New-onset erectile dysfunction or impotence was the second most commonly reported side effect, occurring in 24% (9 of 28) of those undergoing bilateral IIA embolization.8
In cases where bilateral IIA occlusion is necessary, it has previously been suggested that the use of staged embolizations, allowing a period of days to weeks to elapse between an initial embolization and a second embolization concurrent with stent-graft placement, may decrease the incidence of morbidity as compared to simultaneous bilateral embolization performed at the time of stent-graft placement. Staged embolizations may provide time for collateral pelvic circulation to develop, thus limiting the areas that are permanently or temporarily deprived of blood flow. However, the potential benefits of staged embolizations remain a point of contention, as conflicting outcomes have been reported in some studies.12,13
It has been suggested that another means to decrease morbidity in IIA embolization is by proximal occlusion of the artery, with use of techniques to prevent distal coil migration.12,14,15 Proximal artery occlusion may better allow for the development of collateral pelvic circulation, and thus reduce side effects of IIA occlusion in a manner similar to staged embolizations, i.e., by minimizing ischemia. In one study, the decrease in frequency of side effects reported when such methods were utilized was so impressive as to lead the author to suggest that proper technique might prevent many of the morbidities experienced with IIA embolization.14
In our study, we provide the experience of 6 patients who received bilateral IIA embolization due to the presence of difficult iliac anatomy, as well as 1 patient who experienced inadvertent IIA occlusion with distal aortic stent-graft migration; all except 1 patient underwent related EVAR. Our aim in this retrospective analysis was to share our experience with bilateral IIA occlusion and the incidence of adverse effects, including buttock claudication, erectile dysfunction and colonic ischemia.
Methods
A retrospective chart review was performed, seeking patients who underwent procedures resulting in bilateral IIA occlusion at our institution. Seven such patients were found: all were male and 5 of 7 were Caucasian (2 were African-American), with a mean age of 81.4 years
(range 74–90 years). Procedures of interest occurred between May 2000 and May 2010. All but 1 patient underwent related EVAR; the exception was 1 patient who had bilateral CIA aneurysms but no infrarenal aortic aneurysm.
Of 7 patients, 5 had bilateral CIA aneurysms; 3 of these 5 also had bilateral IIA aneurysms. One patient had a single CIA aneurysm with an IIA aneurysm on the contralateral side, and the remaining patient had a unilateral CIA pseudoaneurysm. CIA aneurysm diameters ranged from 2.5–5.0 cm; the diameter of the pseudoaneurysm was 6 cm. In 2 patients, IIA embolization was performed bilaterally in the same intervention. In the remaining patients, embolization of one IIA occurred 3–28 days before occlusion of the second IIA. Of the 6 patients who completed a subsequent EVAR procedure, 5 underwent planned bilateral IIA embolization and 1 experienced IIA occlusion with inadvertent distal migration of the aortic stent-graft.
All of the patients who had an associated AAA were initially evaluated for their suitability to undergo endovascular repair. All were found to have a suitable proximal neck length, aneurysmal angulation and aneurysm diameter of > 5 cm, considered amenable to EVAR. Distal neck suitability was complicated by the anatomic considerations mentioned above, specifically aneurysms involving the common iliac artery(ies) and adjoining branches.
IIA embolizations were performed in the angiographic suite under local anesthesia. Several commercially available coils were used for the embolization, including Nester (Cook, Inc., Bloomington, Indiana) and interlocking detachable coils (Boston Scientific Corp., Natick, Massachusetts). Amplatzer plugs (AGA Medical, Inc., Plymouth, Minnesota) were also utilized in two separate embolization procedures. In 6 of 7 patients, embolizations were performed at or close to the orifice of the IIA at a proximal location along the artery. In the remaining patient, anterior and posterior branches of the IIA were occluded bilaterally, affecting a more distal embolization. Fluoroscopy and angiography were used during the procedures to aid in anatomic guidance and to confirm successful embolization of the arteries. Manual compression or a vascular closure device (Perclose or StarClose, Abbott Vascular, Abbott Park, Illinois) was used to close the arteriotomy site.
EVAR was performed with a variety of commercially available stent-grafts. All EVAR procedures were performed in the operating room under general or spinal anesthesia. At least one vascular surgeon and one interventional radiologist were present at each procedure. Femoral arteries were accessed bilaterally through standard groin incisions, and intraoperative 
fluoroscopy and angiography were performed to assure proper graft seating and seal, as well as to confirm patency or occlusion of adjacent vessels.
Patient charts were analyzed retrospectively and data regarding the incidence and severity of side effects were collected. Most data came from documentation obtained at follow-up visits where patients were asked about the presence of side effects including buttock claudication and new-onset impotence. Visits occurred from 1–40 months following the procedures where IIA occlusion took place. Patients were also contacted by phone and were asked to complete a brief telephone survey about their experience with the procedure. Surveys consisted of 11 questions that asked about the presence of buttock claudication and new-onset impotence and the resolution of these symptoms as applicable. Five of 7 patients participated in the telephone survey and 1 patient completed the survey in person at a follow-up clinic visit.
Results
Between May 2000 and May 2010, 7 patients underwent procedures at our facility that resulted in occlusion of blood flow to both IIAs. There were 12 IIA embolizations, 1 occurrence of distal stent-graft migration with inadvertent coverage of the IIA orifice and 1 CIA embolization with an Amplatzer plug (AGA Medical). All IIA and CIA embolizations were technically successful, with confirmation of arterial occlusion obtained by angiography. Five patients had an AAA and received IIA embolization to facilitate EVAR. Of these, 4 patients had aneurysms bilaterally that affected the common and/or internal iliac arteries, and 1 patient had a unilateral 
CIA aneurysm. This last patient received unilateral IIA embolization and experienced bilateral IIA occlusion with inadvertent distal migration of an aorto-iliac stent-graft.
Two patients had aneurysms of the CIAs without a coexisting AAA and underwent IIA embolization to facilitate aneurysm repair. Of these, 1 patient received EVAR and the other underwent bilateral endovascular CIA stenting.
Complications. One patient included in the study had a history of aorto-iliac grafting for AAA repair 24 years previously. The patient presented with left distal pseudoaneurysm formation at the site of the graft anastamosis; he subsequently underwent several procedures in order to prevent further pseudoaneurysm enlargement, including initial endovascular stenting of the pseudoaneurysm. At a 6-month follow-up visit, enlargement of the pseudoaneurysm was detected, with no detectable source. The patient subsequently underwent left IIA embolization, followed by a third intervention which consisted of placement of a Zenith AAA unibody endograft (Cook), right CIA occlusion with an Amplatzer plug and femoral-femoral bypass with anastamosis to the right external iliac artery. These measures were successful in terminating enlargement of the pseudoaneurysm.
Approximately 3 months after the endograft placement and bypass procedure, the patient experienced a new-onset symptom of thigh claudication. Computed tomographic (CT) angiography revealed an aorto-uni-iliac endograft that was completely thrombosed, occluding the infrarenal aorta. The femoral-femoral graft was also completely thrombosed. An axillary-femoral bypass grafting procedure was completed without complications, and the patient tolerated the procedure well. At a 6-month follow-up visit after this final procedure, the patient was doing well with no reported complaints.
Clinical outcomes. Of the 7 patients who underwent bilateral occlusion of blood flow to the IIAs, there were no incidences of perioperative mortality and no reported incidences of stent-graft infections. No occurrences of transient or permanent spinal cord ischemia were documented. There were also no reported incidences of pelvic necrosis, colonic ischemia or scrotal skin sloughing. One patient experienced bilateral groin hematomas at the site of the femoral cut-downs for an EVAR procedure, which was the only perioperative complication reported.
One patient who underwent EVAR following IIA embolization was found to have an enlarging aneurysmal sac at a 16-month follow-up visit, which required re-intervention. This patient and the patient detailed above in the Complications section were the only patients in the series to date that have required re-intervention for the presence of an endoleak or for any other complication after completion of EVAR.
Documentation of the presence or absence of side effects as found in patient charts was verified during telephone interview follow-up. Four of 7 patients (57%) in our series reported the presence of buttock claudication after the embolization procedures. Two of these 4 patients (50%) reported complete resolution of the claudication by 18 months following the second embolization procedure. The remaining 2 patients (50%) reported persistence of claudication, with no improvement at the time the telephone interview was conducted. In 1 of these patients, however, the telephone interview was conducted after only approximately 6 weeks had elapsed since the most recent embolization procedure (see discussion below). In the 2 patients who reported complete resolution of claudication, time to resolution was reported as 12 months in 1 patient and 18 months in the other.
In our series, 3 of 7 patients (43%) had reported preexisting erectile dysfunction, which was not reported to have worsened with any intervention. Two patients (29%) reported new-onset impotence following the second IIA embolization procedure.
One patient died approximately four and a half months after undergoing bilateral IIA embolization, before endovascular repair of his AAA could be completed. The patient died before this procedure could be performed due to rupture of a coexisting thoracic aortic aneurysm. This patient is the only participant in the series who is now deceased; he was the oldest participant at age 90 years of age. At this patient’s last office visit, which occurred three and a half months after completing IIA embolization, he did not report experiencing any buttock or thigh claudication, but he was 1 of the 2 patients who reported new-onset impotence.
Discussion
Endovascular repair is increasingly being used as a nonoperative method for managing aneurysms of the aorta and iliac arteries. EVAR, in particular, is enjoying increased utilization. Patients who are appropriately selected candidates for EVAR have been shown to benefit from decreased perioperative mortality and decreased incidence of moderate and severe cardiovascular, renal and pulmonary complications.1–3 However, EVAR may be complicated by difficult iliac artery anatomy, making it necessary to occlude flow to one or both IIAs in order to insure proper seal around the aorto-iliac graft. IIA occlusion may also be necessary for successful endovascular repair of common iliac or external iliac artery aneurysms. The reported side effects associated with bilateral IIA occlusion include buttock claudication, impotence and more serious sequelae such as colonic and spinal cord ischemia. These side effects have caused interventionists to seek methods to minimize ischemia, including using techniques for embolization and novel surgical procedures to revascularize areas supplied by the IIAs.16,17
In our study, we add to the data currently available about bilateral IIA occlusion and the side effects resulting from this procedure. Our results corroborate those derived from previous studies that found buttock or thigh claudication to be the most common side effect experienced by patients who underwent bilateral IIA occlusion. Buttock claudication occurred with a frequency of 57% (in 4 of 7 patients) in our series — a percentage somewhat greater than the 35% reported by Rayt et al in their study consisting of data pooled from 18 studies and that were contributed by his institution. However, our frequency is consistent with those reported in studies with similar numbers of participants8,11 and also falls within the range of frequencies of claudication (13–80%) found in studies compiled by Rayt et al.8
Two of 4 patients (50%) in our series who experienced claudication reported resolution of symptoms by 18 months following the second IIA embolization/occlusion procedure, while the remaining 2 patients (50%) experienced no diminution of claudication. Telephone interviews of these patients were conducted with 1 patient at 6 weeks following the second embolization procedure and at 30 months post procedure in the other patient. Whether the former patient will experience relief of symptoms once farther removed from the embolization procedures remains to be seen; thus, a determination of frequency of apparent permanent claudication is unable to be made at this time.
There were 2 incidences of new-onset impotence in our study (2 of 7 patients, 29%), similar to the 24% overall frequency reported by Rayt et al in patients who underwent bilateral IIA embolization.8 In our series, there were no reports of colonic ischemia, spinal cord ischemia or scrotal skin sloughing, which corroborates conclusions drawn from previous data that suggest these side effects are rare occurrences.5–7
One patient in our series reported experiencing both claudication and new-onset impotence following the second IIA embolization procedure. Review of procedure reports indicated that this patient had both anterior and posterior branches of the IIA embolized bilaterally; thus, he was the only patient in the series to have had embolizations performed at a distal location. Although only the experience of 1 patient, this outcome may lend support to conclusions drawn from other data suggesting that distal IIA embolization results in increased morbidity as compared to proximal IIA embolization.14,15
Two of 7 patients in the study received simultaneous bilateral IIA embolization in a single intervention, with no staging between embolizations. One of these patients (50%) reported the presence of claudication post procedure, which was unresolved at 30 months. Neither patient reported the occurrence of new-onset impotence. Of the 5 patients who received staged embolizations, with 3–28 days elapsing between procedures, 3 experienced buttock claudication (60%); complete resolution of claudication occurred by 18 months in 2 of these patients. The remaining patient, who reported no resolution of claudication, was described above as the one who was contacted only 6 weeks following the second embolization procedure. Two of 5 patients (40%) who received staged embolizations reported new-onset impotence. Thus, in our series, staged embolizations provided no benefit in decreased morbidity as compared to simultaneous embolization procedures.
Conclusion
In summary, the results of our analysis reaffirm findings from other studies that report buttock claudication to be the most frequently encountered side effect of bilateral IIA occlusion, followed by new-onset impotence. The lack of incidence of colonic or spinal cord ischemia in our series support the view that these are rare events, and that bilateral IIA occlusion may be safely utilized with an acceptable amount of risk when this procedure is necessary. Utilizing techniques to embolize proximal as opposed to distal portions of the artery may minimize the morbidity associated with this procedure. In our series, no benefit was gained from the use of staged versus simultaneous IIA embolizations.
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From *Chicago Medical School at Rosalind Franklin University of Medicine and Science, Chicago, Illinois; and Kaiser Permanente Los Angeles Medical Center, Los Angeles, California. The authors report no conflicts of interest regarding the content herein. Manuscript submitted August 22, 2010, provisional acceptance given November 2, 2010, and final version accepted November 29, 2010. Address for correspondence: George Vatakencherry, MD, Kaiser Permanente Los Angeles Medical Center, 10980 Wellworth Avenue, Los Angeles, CA 90024. E-mail: gvataken@hotmail.com
