Endovascular abdominal aortic aneurysm repair in patients with common iliac artery aneurysms – Initial experience with the Zenith bifurcated iliac side branch device

Methods 

Between November 2005 and October 2006, all patients who were being considered for EVAR and were going to require coverage of at least one of their internal iliac artery origins by the stent graft to obtain a seal were offered the IBD. Informed consent, stressing the as yet unknown long-term outcome of the device, was obtained from all patients. All eight patients to whom this treatment modality was offered accepted to have an IBD device as opposed to losing an internal iliac artery. In two patients (cases 1 and 2 in Table I, Table II), the IBD was used in conjunction with a standard Zenith Flex main body, a Zenith side branch occluder, and extension grafts to exclude an infra-renal aortic aneurysm with bilateral common iliac artery aneurysms. In another four patients, it was used in conjunction with a standard Zenith Flex main body, and extension grafts to exclude an infra-renal aortic aneurysm with a single common iliac artery aneurysm in three patients (cases 3 to 5 in Table I, Table II) and a solitary common iliac aneurysm in one patient (case 6 in Table I, Table II). In another patient (case 7 in Table I, Table II), a juxta-renal abdominal aortic aneurysm with bilateral common iliac aneurysms had already been previously managed using a two-vessel fenestrated Zenith graft, and a Zenith side branch occluder in the larger common iliac artery. The IBD was inserted as a secondary procedure to treat a distal type 1 endoleak. In another patient (case 8 in Table I, Table II), it was used to treat a right 3.5 cm internal iliac aneurysm. The patient had previously had a 5 cm left internal iliac aneurysm treated with a Viabahn Excluder stent. Further patient details are given in Table I.

Table I. Patient age and aneurysm dimensions pre-procedure and at last follow-up

	Patient	Age (years)	Follow-up (months)	Side of IBD	AAA diameter (cm)pre-procedure	AAA diameter (cm)at last follow-up	Right common Iliac diameter (cm) pre-procedure	Right common Iliac diameter (cm) at last follow-up	Left common Iliac diameter (cm) pre-procedure	Left common Iliac diameter (cm) at last follow-up
	1	80	3	Right	5.0	4.6	3.5	3.9	3.5	3.9
	2	64	8	Left	6.2	6.0	3.9	3.9	2.6	2.7
	3	77	6	Left	5.8	4.0	1.6	1.6	2.9	2.0
	4	67	14	Right	5.4	2.9	3.2	1.9	2.0	2.4
	5	69	1	Right	5.4	5.4	2.1	1.8	1.5	1.5
	6	75	5	Right	2.0	2.0	3.7	3.4	2.4	2.4
	7	65	12	Left	5.8	5.6	6.3	5.8	4.3	4.3
	8	80	1	Left	2.8	3.0	3.6 [5.0]	3.4 [5.3]	3.3 [3.6]	3.3 [3.8]

For case 8, internal iliac artery diameters are also given in square brackets, since this patient also had bilateral internal iliac aneurysms which were his main pathology.

Table II. Contrast use and fluoroscopy screening time

	Patient	Type of contrast (volume in ml)	Contrast used as g of Iodine	Fluoroscopy time
	1	Iomeron 300 (373)	112g	57 minutes
	2	Isovue 370 (284)	105g	49 minutes
	3	Iomeron 300 (433)	130g	48 minutes
	4	Isovue 370 (237)	88g	43 minutes
	5	Isovue 370 (227)	84g	38 minutes
	6	Isovue 370 (332)	123g	70 minutes
	7	Isovue 370 (237)	88g	105 minutes
	8	Isovue 370 (264)	98g	83 minutes

Device characteristics and planning 

The Zenith bifurcated iliac side branch device resembles a standard Zenith limb extension but has a side branch attached to its body approximately half way down its length as shown in Fig 1. In order to use this device, the external iliac artery must not be aneurismal in order to provide a distal fixation segment. This vessel must therefore be at least 20 mm long and have a diameter between 8 and 11 mm. The internal iliac artery must also be of normal caliber with a length of at least 10 mm to allow for proper sealing. The graft is constructed of full-thickness woven polyester fabric sewn to self-expanding stainless steel and nitinol Cook Z-stents. The graft is fully stented. This provides stability as well as the expansile force necessary to open its lumen during deployment. Nitinol rings positioned at the proximal end of the graft help maintain lumen patency during access. Additionally, the Cook Z-stents provide the necessary seal between the graft and vessel wall. Long gold markers are used to mark the outer side of the side branch, which is supported by a nitinol stent and two 7 mm reinforced rings. The inner distal diameter of the side branch is 8 mm. The main stent has a proximal diameter of 12 mm. The device is tailored to the patient’s anatomy based on the length of the common iliac artery aneurysm and the length and diameter of the external iliac artery. When planning the device, one has to keep in mind that the distal end of the side branch will lie 10 mm above the iliac bifurcation (see Fig 2) and the proximal end of the common iliac segment needs to lie as close as possible to the aortic bifurcation. The diameter of the external iliac segment is oversized by 10%. Planning of these devices was based on maximum intensity projection (MIPs) from computed tomography (CT)-angiograms and conventional angiography with a calibrated pig-tail catheter in all patients. All the devices used were custom made (Cook Australia Pty Ltd, Brisbane, Queensland, Australia) for each individual patient and loaded into a 20F sheath, with a curved indwelling catheter and guidewire through the side branch to facilitate its cannulation from the contralateral side by snaring of this wire.

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Fig 1. Photograph of the unsheathed Zenith bifurcated iliac side branch device. A, Anterior/posterior view; B, Side view to demonstrate the gold markers. The balloon expandable covered stents that are used to bridge the gap between the side branch and the internal iliac artery must not extend proximally above the third gold marker (counting from above). [Courtesy of William A. Cook Australia Pty Ltd].

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Fig 2. Line diagrams depicting deployment of the Zenith bifurcated iliac side branch device (IBD): A, The indwelling catheter is snared within the aortic aneurysm sac and brought out via the contralateral femoral artery. B, The IBD is partly deployed to open up its side branch prior to advancing the Balkin sheath over the through-and-through wire, into the proximal segment of the IBD and out of its side branch, C. Another 0.035 wire is then introduced through the Balkin sheath to allow cannulation of the internal iliac artery. D, This wire is then changed to a stiffer wire over which covered stents are introduced and later deployed after fully unsheathing the IBD. [Line diagrams used with permission of William A. Cook Australia Pty Ltd.]

Operative technique 

Endovascular access is obtained through both common femoral arteries. The IBD is introduced over a Lunderquist wire, the contralateral side being used for angiography to allow correct positioning. The pre-mounted wireguide (within the side branch of the device) is exchanged for a 0.035-inch stiff shaft Glidewire (Terumo Medical Corporation, Somerset, New Jersey). The tip of this wire is advanced well into the aneurysm sac and retrieved from the contralateral access site (Fig 2, A). After partially deploying the IBD thereby allowing its side branch to open, a 12 Fr Balkin sheath is advanced over the through-and-through wire, over the aortic bifurcation, into the proximal opening of the IBD and out of its side branch (Fig 2, B and Fig 3, A). A new 035-inch stiff shaft Glidewire (Terumo Medical) is then advanced through the Balkin sheath to cannulate the opposite internal iliac artery (Fig 2, C). In one patient, this was unsuccessful and the internal iliac artery was cannulated with access through the left brachial artery. The wire is advanced into a distal side branch of the internal iliac artery and exchanged for an Amplatz Superstiff Guidewire (Boston Scientific, Natick, Mass). The external iliac part of the IBD is opened into place. Advanta V12 covered stents (Atrium Medical, Hudson, New Hampshire) are deployed, from the internal iliac artery (or its largest normal branch [in case 8] when an internal iliac aneurysm is also present) to the side branch of the IBD, ensuring good sealing and patency (Fig 2, D and Fig 3, B). The Balkin sheath and Amplatz Superstiff Guidewire (Boston Scientific) are removed and a Zenith flex graft introduced from the side opposite the IBD over a Lunderquist wire and deployed in the standard fashion immediately distal to the origin of the renal arteries. If required, a Zenith side branch occluder is introduced and deployed to occlude the internal iliac artery on the opposite side of the IBD prior to insertion of the main body. A leg extension is introduced and deployed to bridge the ipsilateral leg of the main body device and the distal segment of the Zenith side branch occluder or native common iliac artery. Another leg extension with a distal diameter of 16 mm is introduced and deployed to bridge the contralateral leg of the main body device and the IBD.

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Fig 3. Intraoperative fluoroscopy and digital subtraction images from case 3. A, Balkin sheath advanced over the aortic bifurcation, into the side branch of the partially deployed Zenith bifurcated iliac side branch device (IBD); B, The internal iliac artery has been cannulated and the wire advanced well into one of its branches, the IBD has been completely deployed, one covered stent has also been deployed, and a second one is about to be deployed; C, Completion angiograph at the end of the procedure (the right limb is not filling since no suction was applied to the sheath in the right groin to better visualize the left side).

In the patient who had the fenestrated graft, since all the other stent grafts were already in place when the IBD was inserted, cannulation of the internal iliac artery was performed via a left brachial approach.

Completion angiography is performed to assess patency and look for endoleak (Fig 3, C, Fig 4, B, and Fig 5, B). Patients were followed with clinical examination, plain abdominal x-ray, and color and power Doppler ultrasound at monthly intervals.

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Fig 4. Intraoperative digital subtraction images from case 5. A, Before stent insertion and deployment; B, At completion.

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Fig 5. Intraoperative digital subtraction images from case 7: A, before stent insertion and deployment, demonstrating a distal type 1 endoleak despite the previous use of a “bell-bottom” technique and B, at completion demonstrating no endoleak after deployment of the Zenith bifurcated iliac side branch device and Advanta V12 stents.

Results 

During the study period, we treated a total of 69 patients with aorto-iliac aneurismal pathology. Twenty-one of these patients were treated by open surgery. Of these, seven required a bifurcated graft. Forty-eight patients were treated by endovascular means, eight of whom were offered an IBD since they had a common iliac artery (CIA) diameter on at least one side greater than 25 mm.

Table II gives details of the fluoroscopy time and amount of contrast used. The median operative time was 215 minutes (range 152 to 414). There was minimal blood loss, with only one patient requiring a postoperative blood product transfusion. All the stent-grafts were deployed as planned. The length of the common iliac artery component of the IBD was 41, 65, or 83 mm, and that of the external iliac artery component of the IBD was 41 or 58 mm. Seven patients required two 8 mm and one patient required two 10 mm Advanta V12 covered stents (Atrium Medical) of various lengths to obtain a good seal. Distal diameters for the external iliac artery component of the IBD were 12, 14, and 16 mm. Completion angiography showed that all the aneurysms were fully excluded with no endoleak. Postoperative in-patient stay varied between 3 and 5 days with a median value of 4. All patients are alive at follow-up with no major complications. Two patients, however, have recurrent groin lymphoceles that are being managed conservatively.

Table I gives details on the aneurysm size at follow-up (median: 6; range: 1 to 14 months). None of the aneurysms have increased significantly in size since intervention. The patient who had a previous fenestrated graft has been found to have a type 2 endoleak from the inferior mesenteric artery. This is being closely observed with a view to intervention only if the aneurysm increases in size. To date, none of the other seven patients have demonstrated any endoleak. There was only one occlusion of an IBD, in the patient who had an internal iliac artery aneurysm. This resulted in no significant symptoms. All the other side branches remain patent with good velocities in the preserved internal iliac artery on duplex ultrasound. There were no cases of colonic ischemia and none of the patients complained of new claudication symptoms or new onset impotence at follow-up.

Discussion 

As a result of the decreased morbidity following EVAR when compared with open aneurysm repair, there has been an increase in the demand for endovascular treatment of patients with aorto-iliac aneurysms. To this effect, a number of reports on how to treat patients with aorto-bi-iliac aneurysms with EVAR whilst at the same time preserving one internal iliac artery have appeared in recent literature. Parodi and Ferreira15 were the first to propose surgically relocating the origin of the internal iliac artery further distally on the external iliac artery. This procedure is, however, technically demanding, especially in patients with large iliac aneurysms, takes time, and requires significant retroperitoneal exposure. It therefore defeats the whole purpose of the minimally invasive nature by which EVAR benefits patients. As a result, a number of authors have used stent-grafts in combination with EVAR to preserve internal iliac artery flow on one side. Until recently, however, these procedures also necessitated a femoro-femoral crossover graft. Bergamini and colleagues16 used a custom-made aorto-uni-iliac device on the side where they embolized the internal iliac artery, performed a femoro-femoral crossover, and on the contralateral side, used a custom-made covered stent or a Wallgraft (Boston Scientific) to retrogradely perfuse the internal iliac artery from the ipsilateral external iliac artery and at the same time exclude the common iliac artery aneurysm proximal to it. Delle and coworkers17 used an excluder bifurcated stent-graft (WL Gore & Associates, Flagstaff, Ariz). They inserted the main device through the same side where the internal iliac artery was coiled and used a standard limb extender to seal in the external iliac artery on this side. On the contralateral side, they used various covered stent grafts, usually Hemobahn (WL Gore & Associates) to bridge the gap between the distal end of the main body’s limb and the internal iliac artery. The procedure was then completed by performing a femoro-femoral crossover graft and ligating the external iliac artery.

The IBD is a novel endovascular device that enables the exclusion of aorto-bi-iliac aneurysms, whilst simultaneously preserving at least one internal iliac artery without the need for an additional open surgical procedure. In this series, we only used unilateral IBDs. In case 1 and 2 with bilateral common iliac aneurysms, we occluded the contralateral internal iliac artery with a Zenith side branch occluder, since we believed that it was impossible to obtain a safe seal proximal to its origin. In case 1, there was no anatomical difference between either one of the common iliac arteries and, so, we put the IBD on the right side as opposed to the left for no specific reason. In case 2, we decided to deploy the IBD in the smaller of the two common iliac aneurysms, as we believed that this would result in a shorter length of covered stent to bridge the side branch of the IBD and the origin of the internal iliac artery. Although we could have elected to use bilateral IBDs, we felt that at this stage when our experience with this novel device is still limited, the increase in need for fluoroscopy time, the increased usage of contrast, the longer anesthetic time, as well as the additional need for vascular access from the arm to cannulate the second IBD side branch, and internal iliac artery would have increased the risk of the procedure, possibly outweighing the benefits. Cases 7 and 8 had an internal iliac artery previously occluded to treat previous contralateral pathology, and there would have been no choice other than to occlude the other IIA as well had the IBD device not been used.

This report, compliments that of Malina’s group from Sweden18 in confirming that the IBD may be used to completely exclude aorto-iliac aneurysms with minimal morbidity and excellent short-term results. Although our data shows that contrast usage and fluoroscopy times are considerably higher than published data for conventional cases, we believe that these will decrease as familiarity with the procedure increases. Despite the number of modular components involved, we did not observe any endoleaks related to the IBD. Malina’s group did, however, have one case of type 3 endoleak on follow-up in one of the ten patients they treated with the IBD. Greenberg and coworkers19 have also just recently published their experience with a similar device, also based on a Zenith (Cook) platform. Their common iliac aneurysm device resembles a conventional limb extension with a 2 cm long crimpled fabric tube 6 or 8 mm in diameter anastomosed as a branch. Unlike the IBD, this branch arises from the side lateral to the internal iliac artery to assume a helical path around the device. In their series of 21 patients, they failed to access the internal iliac artery in three, and had three limb occlusions all of which were successfully treated with thrombolysis and bare stenting. Malina and coworkers18 also reported one case of late external iliac occlusion in their series. Since their patient reported no symptoms, they did not treat this. In our series, we had no case of limb occlusions. We did, however, have one case where the stented internal iliac artery occluded. This occurred in the patient who had an internal iliac aneurysm and, therefore, had the stent sealing in the largest branch of the internal iliac artery after embolization of the other branches at a previous procedure. Although the cause of the occlusion remains unclear, it may well be that this was due to a combination of the smaller diameter of this vessel when compared with normal internal iliac artery and the longer course of the covered stents to reach this vessel. Despite this, we would still consider using IBDs to treat IIA aneurysms in the future, since when one compares this with embolization and covering the IIA origin with a stent-graft (our first line treatment prior to the development of the IBD), there is nothing to be lost if the side branch occludes.

Conclusion 

In conclusion, the IBD provides a new alternative for the management of patients with aorto-iliac aneurysms, that is not only safe, but also less complex than previous endovascular or hybrid methods that attempted to exclude these aneurysms whilst maintaining pelvic blood flow.

Author contributions