| | Preservation of pelvic circulation with hypogastric artery bypass in endovascular repair of abdominal aortic aneurysm with bilateral iliac artery aneurysmsReceived 28 April 2006; accepted 4 August 2006. PurposeThe endovascular repair (EVAR) of an abdominal aortic aneurysm (AAA) with a bilateral common iliac artery aneurysm (CIAA) often requires exclusion of the bilateral hypogastric artery (HA), which can be associated with pelvic ischemic complications such as erectile dysfunction and buttock claudication. This study assessed the effect of HA bypass on improving pelvic circulation. MethodsFive patients who underwent endovascular repair with HA bypass for an AAA with bilateral CIAA were evaluated. In all patients, the patency of the inferior mesenteric artery and bilateral HAs arteries was confirmed with preoperative computed tomography (CT) scans and angiography. During EVAR, penile blood flow was monitored with pulse-volume plethysmography measuring the penile brachial pressure index (PBI), and bilateral buttock blood flow was monitored with near-infrared spectroscopy measuring the gluteal tissue oxygenation index (TOI). An aortouni-external iliac artery stent graft with a crossover bypass was performed after embolization of the contralateral HA. HA bypass was performed between the crossover bypass graft and the ipsilateral HA via a retroperitoneal incision. ResultsUnilateral coil embolization of the contralateral side HA trunk slightly decreased blood flow to the contralateral side buttock but did not cause significant changes in penile blood flow. At the completion of EVAR, the levels of both PBI and the contralateral side TOI were significantly lower than the baseline levels. After ipsilateral side HA revascularization with HA bypass, both PBI and bilateral gluteal flow returned almost to the baseline levels. Postoperative angiography and CT scans demonstrated the patency of all HA bypasses and no endoleaks. None of the patients experienced new onset of erectile dysfunction or buttock claudication 1 month after surgery. ConclusionBilateral HA interruption during EVAR for AAA with bilateral CIAA was associated with significant depletion of both penile and gluteal blood flow. Intraoperative monitoring of PBI and TOI at the bilateral buttocks showed significant improvement of both parameters after HA bypass. HA bypass is an excellent procedure to improve pelvic circulation despite its increased surgical complexity. Endovascular abdominal aortic aneurysm (AAA) repair (EVAR) has demonstrated decreased surgical morbidity and good patient recovery.1, 2, 3 The technique has been applied to AAA treatment worldwide, and the number of procedures has increased each year.4 However, EVAR for AAA with bilateral common iliac artery aneurysm (CIAA) often requires exclusion of the bilateral hypogastric artery (HA) with coil embolization and deployment of the distal aspect of the stent graft in the external iliac artery (EIA) to achieve exclusion of the aneurysm from arterial circulation. In addition, when the hypogastric artery aneurysm (HAA) is concomitant, these aneurysms should be excluded together. These maneuvers, however, are often associated with hip or buttock claudication, and impotence due to pelvic hypoperfusion.5, 6 To avoid such complications, revascularization of HA has been recommended to preserve pelvic circulation.7, 8 When the HA blood flow is interrupted during EVAR, no intraoperative monitoring method is available to assess pelvic circulation. We recently introduced a new monitoring system to assess buttock blood flow uses near-infrared spectroscopy (NIRS), and pulse-volume plethysmography for measurement of penile brachial pressure index (PBI) during EVAR.9 We used this monitoring system to assess the effect of HA bypass on pelvic circulation in EVAR for AAA with bilateral CIAA and also the clinical outcome of the surgery. Materials and methods  Between February 2004 and March 2006, 31 patients underwent elective endovascular repair of aortic or aortoiliac aneurysm at our department. Until July 2006, the Japanese government had not approved the import of commercial endovascular grafts. Therefore, a custom-made aortouniiliac stent graft with crossover bypass was used in all patients. Retrograde flow to the contralateral CIA was interrupted with coil embolization of the CIA, unless the contralateral CIA was aneurysmal. The stent graft was made from a Gianturco Z-stent (Cook Inc, Bloomington, Ind) and a spiral Z-stent (Medico’s Hirata Inc, Osaka, Japan), which was tapered and sutured to a woven polyester graft (UBE Corp, Ichihara, Japan). Of the 31 patients who had procedures, only five were registered for this study because they had an AAA with a bilateral CIAA and a patent inferior mesenteric artery (IMA). HA bypass was performed after EVAR. Before entry into the study, each patient was fully informed of the nature, the aim, and expected and possible side effects of this study, and then informed consent was obtained from all participating patients. None of the five patients had peripheral artery occlusive disease. A preoperative angiogram confirmed that all patients had patent bilateral HAs and IMA, and three had visible patent lumbar arteries. A preoperative angiogram also identified patent bilateral profunda femoris arteries in all five patients. An aortouni-EIA stent graft implantation with a crossover bypass was performed. Under general anesthesia, the contralateral HA was embolized with a coil at the main trunk. Among these five patients, one patient had a contralateral internal iliac artery aneurysm; therefore, we embolized the first branches of the HA along with main trunk embolization. The ipsilateral iliac bifurcation was mobilized through a retroperitoneal incision. After the patient received systemic heparinization, a 22F stent graft delivery sheath (Medikit Co, Ltd, Hyuga, Japan) was inserted through the EIA. The stent graft was deployed between the infrarenal abdominal aorta and ipsilateral EIA. A crossover bypass was performed using an 8-mm knitted Dacron graft (Vascutek Gelsoft ERS, Vascutek, Ltd, Renfrewshire, Scotland, UK). The proximal anastomosis of the crossover bypass came off the EIA, where the delivery sheath was inserted. The distal anastomosis of the bypass was placed at the contralateral common femoral artery. The proximal region of the common femoral artery was ligated. Then, a crossover bypass graft to ipsilateral HA bypass was constructed with an 8-mm knitted Dacron graft. The proximal anastomosis of the bypass was performed in an end-to-side fashion, and the distal anastomosis was performed in an end-to-end fashion after mobilization of the distal part of the HA. The proximal part of the HA was oversewn with 4-0 polypropylene suture for hemostasis. After declamping, pelvic circulation was restarted through the HA bypass. Postoperative angiography was performed in every patient to confirm the patency of the HA bypass and endoleaks (Fig 1). Six time points for monitoring pelvic blood flow We monitored pelvic blood flow at the following six time points (Fig 2): A—before HA flow interruption. B—after interruption of contralateral HA flow with coil embolization. C—after bilateral interruption of both HA and EIA flow. At this time, the stent graft was deployed below the renal artery, and the delivery sheath was still inside the EIA just distal to the stent graft. All pelvic circulation, therefore, was blocked (ie, IMA, lumbar artery, bilateral HAs and bilateral limb perfusion), except for a limited volume of collateral perfusion from the superior mesenteric artery. D—after revascularization of the ipsilateral EIA with interruption of both bilateral HA flow and contralateral EIA flow. E—after revascularization of bilateral EIA with interruption of bilateral HA flow. F—after revascularization of ipsilateral HA with interruption of contralateral HA flow. Monitoring of pelvic blood flow Intraoperative monitoring during EVAR was conducted as described previously.9 Briefly, penile blood pressure was repeatedly measured with an oscillometric cuff placed on the patient’s penis to assess penile blood flow. The penile brachial pressure index (PBI), defined as the ratio of penile blood pressure divided by brachial systolic blood pressure, was automatically calculated with form PWV/ABI (BP-203RPEII; Omron Colin Co, Ltd, Tokyo, Japan). With this device, PBI was repeatedly measured without manual manipulation during EVAR. To monitor gluteal blood flow, two NIRS probes were positioned on each side of the buttocks. An NIRS instrument (NIRO-300; Hamamatsu Photonics KK, Hamamatsu, Japan) was used to continuously monitor the tissue oxygenation index (TOI), which was calculated as the ratio of oxygenated hemoglobin to total hemoglobin in tissue. Because TOI is a relative value at the buttock, it was expressed as the percentage of change compared with baseline values obtained at the starting time. To distinguish each side of the buttocks, we designated the side ipsilateral to the aortouniiliac stent graft as “ipsilateral” and the contralateral side as “contralateral,” Throughout surgery, systemic oxygen saturation was monitored with pulse oximetry. During EVAR and HA bypass surgery, we recorded data at six time points shown in Fig 2. PBI and TOI were recorded 5 minutes after each procedure. Statistical analysis Patient demographic data and surgical variables were expressed as the mean ± SD. One-way analysis of variance (ANOVA), followed by the Tukey test, was performed to test differences in the mean TOI value between ipsilateral and contralateral. Comparisons of PBI or TOI at different time points within each group were analyzed by two-way ANOVA for repeated measures. P < .05 was considered significant. Results Five men underwent HA bypass as an adjunct to EVAR. Surgery was successfully accomplished in all cases. Average patient age, mean diameter of aortoiliac aneurysms, the size of the IMA on preoperative CT, preoperative and postoperative ankle-brachial index (ABI), preoperative erectile function, and surgical parameters are summarized in the Table. Postoperative angiography (Fig 1, B) and CT scan demonstrated good patency in all of the HA bypasses. There were no endoleaks. All patients had an uneventful postoperative course. Preoperatively, three of the five patients had erectile dysfunction and remained impotent postoperatively; postoperative erectile dysfunction did not develop in the other two. None of the patients complained of buttock claudication postoperatively. Monitoring of penile blood flow Contralateral HA embolization decreased PBI slightly at time point B (0.71 ± 0.22), but there was no significant difference compared with the initial value at time point A (0.86 ± 0.30). At time point C, 5 minutes after stent graft deployment with its delivery sheath still remaining in EIA, the PBI dropped below the level that the device could measure blood pressure oscillometrically. At time point D, the PBI increased to 0.30 ± 0.18. At time point E, the PBI further increased to 0.37 ± 012; however, this value was significantly lower than that at time point A (P < .01). At time point F, 5 minutes after revascularization of HA, the PBI recovered to 0.76 ± 0.13 (Fig 3). Monitoring of bilateral gluteal flow At time point B, the contralateral TOI decreased to –12.5% ± 3.7% of the baseline value, but the ipsilateral TOI did not change. At time point C, the bilateral TOI decreased to almost –30% of the baseline. Then, at time point D, revascularization of the ipsilateral limb increased ipsilateral TOI (–10.0 ± 7.3), but contralateral TOI remained low (–26.5 ± 11.0). At time point E, completion of crossover bypass and revascularization to the contralateral limb slightly increased the bilateral TOI; however, the values of the contralateral TOI were significantly lower than baseline value (–3.1 ± 4.2 ipsilateral and –19.4 ± 5.0 contralateral, respectively). After completion of HA bypass (time point F), the TOI returned to the baseline values bilaterally (Fig 4). Throughout surgery, systemic oxygen saturation was monitored with pulse oximetry. The surgical record showed that oxygen saturation remained quite stable in all cases, even in a patient who had significant blood loss. Discussion The HAs and their branches are characterized by an ample network of anastomotic connections with arteries such as the IMA, lumbar arteries, external iliac arteries, and profunda femoral arteries.10 Therefore, to study the effect of HA bypass as an adjunct to EVAR on pelvic circulation, we carefully chose patients with similar pelvic hemodynamics. In this study, all patients who underwent EVAR for AAA with bilateral CIAA were confirmed to have patent bilateral HAs and an IMA preoperatively. Moreover, preoperative angiography and ABI measurement were performed to deny peripheral artery occlusive disease and confirm the patency of the HAs and IMA. Under the hemodynamic conditions described, we performed aortouni-EIA stent grafting and crossover bypass with ipsilateral HA bypass after contralateral HA coil embolization. During EVAR with HA interruption, no monitoring system is available to assess pelvic circulation. However, pelvic ischemic complications such as new onset of impotence and persistent buttock claudication have been reported to occur in 10% to 50% of patients after EVAR with HA interruption.11, 12, 13, 14, 15 We previously used the NIRS system to reveal that the change in ipsilateral gluteal blood flow differed from that of the contralateral gluteal blood flow during EVAR, so that blood flow at each buttock should be monitored separately.9 For that purpose, monitoring probes should be applied to each buttock without contamination of the surgical field. In this study, we applied the same monitoring system to assess changes in pelvic circulation before and after the HA bypass. Our results suggested that unilateral coil embolization of the HA trunk slightly decreased blood flow to the buttock on the same side, but it did not cause significant changes in penile blood flow when both hypogastric arteries were patent, the IMA was patent, and there was no evidence of peripheral artery occlusive disease. With bilateral interruption of both HAs and the EIA, the bilateral gluteal TOI and PBI were both significantly depressed. With unilateral lower extremity reperfusion, PBI and ipsilateral gluteal blood flow both increased, possibly through collaterals of the deep femoral artery and EIA. Completion of the crossover bypass further increased PBI and slightly increased bilateral gluteal blood flow; however the levels of both PBI and contralateral TOI were still significantly lower than the baseline levels, suggesting that completion of EVAR without HA bypass might be associated with erectile dysfunction and serious buttock claudication. In contrast, revascularization of ipsilateral-side HA finally resulted in recovery of both PBI and bilateral gluteal flow almost to the baseline levels. The elevation of contralateral side TOI after ipsilateral HA bypass suggested the existence of collateral networks between bilateral HAs. However, advancement of collateral networks differs in each individual depending on the patency of the preoperative IMA and the HAs with and without peripheral artery occlusive disease, which is difficult to assess preoperatively. AN intraoperative selective HA angiogram, after contralateral HA embolization but before stent graft deployment, may facilitate assessment of the advancement of cross-pelvic collaterals. Moreover, Lin et al14 reported that depressed PBI after EVAR persisted >6 months and continued erectile dysfunction. Therefore, the monitoring of pelvic circulation at each region might be recommended during EVAR, particularly, with HA interruption. In addition, when the monitoring system suggested pelvic malperfusion, performing HA bypass should be considered to maintain pelvic circulation and avoid ischemic complications. The cut-off point for either PBI or TOI to cause ischemic complications is yet to be determined using our monitoring system. With regard to vascular impotence, a previous study reported that the range between 0.6 and 0.8 is the threshold value for concern according to data obtained with Doppler ultrasound scans.16 We have previously demonstrated that our PBI values measured with the oscillometric method were almost identical to those measured with Doppler ultrasound.17 Therefore, it may be better to keep PBI at >0.8 after EVAR. In contrast, concerning the threshold level at which decreased gluteal blood flow causes buttock claudication, to our knowledge, no studies have used NIRS data to investigate the relationship between TOI changes and buttock claudication. Moreover, because buttock claudication is an exercise-induced, dynamic condition, it would be quite difficult to assess the possible occurrence of buttock claudication without muscle activity in this study. Therefore, the simple restoration of TOI with contralateral HA bypass at rest may not have significant clinical implication in preventing buttock claudication. To revascularize HA blood flow, we performed crossover bypass graft-to-ipsilateral HA bypass as an adjunct to an aortouni-EIA stent graft. Various methods have been introduced to revascularize the HAs, such as a contralateral EIA-to-contralateral HA stent graft with an aortouniiliac stent graft,8, 18 EIA-to-HA bypass via a retroperitoneal incision,7, 19, 20 bifurcated stent graft with one side limb extending to HA with crossover bypass,21 and a fenestrated and branched HA revascularization.22 In this study, although the short-term postoperative courses in all patients were uneventful, the amount of intraoperative blood loss was substantially larger than that in our previous series in which we examined perioperative outcomes of EVAR without HA bypass.9 Among the five patients, one patient with severe tissue adhesion around iliac bifurcation lost >1500 mL of blood because of iliac vein injury during mobilization of the HA. The amount of blood loss in the other four patients averaged 500 mL. Caution must therefore be exercised to avoid iliac vein injury. Moreover, the patency of HA bypass should be studied over a longer follow-up in a larger series. Conclusion Bilateral HA interruption during EVAR for AAA with bilateral CIAA caused significant depletion of both penile blood flow and gluteal perfusion. Intraoperative monitoring of PBI and TOI at the bilateral buttocks showed significant improvement of both parameters after HA bypass. HA bypass is an excellent procedure to improve pelvic circulation despite its increased surgical complexity. Intraoperative monitoring of PBI and TOI during EVAR may facilitate selection of patients for HA revascularization. Author contributions Conception and design: NU, KI Analysis and interpretation: NU, KI, NY, HK Data collection: NU, KI, NY, DS, MS Writing the article: NU Critical revision of the article: NU, KI, NY, HK Final approval of the article: NU Statistical analysis: NU Obtained funding: Not applicable Overall responsibility: NU References 1. 1May J, White GH, Waugh R, Ly CN, Stephen MS, Jones MA, et al. Improved survival after endoluminal repair with second-generation prostheses compared with open repair in the treatment of abdominal aortic aneurysms: a 5-year concurrent comparison using life table method. J Vasc Surg. 2001;33:S21–S26. MEDLINE 2. 2Hua HT, Cambria RP, Chuang SK, Stoner MC, Kwolek CJ, Rowell KS, et al. Early outcomes of endovascular versus open abdominal aortic aneurysm repair in the National Surgical Quality Improvement Program-Private Sector (NSQIP-PS). J Vasc Surg. 2005;41:282–289. 3. 3EVAR trial participants. 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19. 19Lee WA, Berceli SA, Huber TS, Seeger JM. A technique for combined hypogastric artery bypass and endovascular repair of complex aortoiliac aneurysms. J Vasc Surg. 2002;35:2289–2291. 20. 20Arko FR, Lee WA, Hill BB, Fogarty TJ, Zarins CK. Hypogastric artery bypass to preserve pelvic circulation: improved outcome after endovascular abdominal aortic aneurysm repair. J Vasc Surg. 2004;39:204–208. 21. 21Delle M, Lonn L, Wingren U, Karlstrom L, Klingenstierna H, Risberg B, et al. Preserved pelvic circulation after stent-graft treatment of complex aortoiliac artery aneurysms: a new approach. J Endovasc Ther. 2005;12:289–295. 22. 22Greenberg RK, West K, Pfaff K, Foster J, Skender D, Haulon S, et al. Beyond the aortic bifurcation: branched endovascular grafts for thoracoabdominal and aortoiliac aneurysms. J Vasc Surg. 2006;43:279–286. Division of Vascular Surgery, Second Department of Surgery, Hamamatsu University School of Medicine, Hamamatsu, Shizuoka, Japan.  Reprint requests: Naoki Unno, MD, Division of Vascular Surgery, Second Department of Surgery, Hamamatsu University School of Medicine, 1-20-1 Handayama, Hamamatsu, Shizuoka 431-3192, Japan.
Competition of interest: none. PII: S0741-5214(06)01390-5 doi:10.1016/j.jvs.2006.08.011 © 2006 The Society for Vascular Surgery. Published by Elsevier Inc. All rights reserved. | |
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