Novel Endovascular Approach Using the Gore Iliac Branch Endograft for Short Iliac Anatomy

Introduction

Abdominal aortic aneurysms (AAAs) are associated with concomitant iliac artery ectasia or aneurysm in up to 40% of cases. ¹ Ensuring adequate proximal and distal seal is paramount for durability of endovascular aneurysm repair (EVAR). In patients with an unsuitable landing zone in the common iliac artery (CIA), the distal landing zone will usually be extended into the external iliac artery (EIA), excluding the internal iliac artery (IIA) with or without coil embolization or occluder devices. Preservation of the IIA is desirable to minimize the risk of buttock claudication, impotence, colon ischemia, and spinal cord ischemia.

To avoid adverse sequelae of IIA occlusion, various open, endovascular, and hybrid measures have been described to maintain perfusion to the pelvis.^2,3 Open surgical options to preserve IIA flow increase the complexity of EVAR and extend the hospital stay. ³ Other less invasive methods involve the use of flared iliac limbs within the CIA ⁴ or iliac branch devices (IBDs).^5–7 These devices are generally employed in cases of aneurysmal CIAs, ⁸ but the presence of short CIAs, frequently described in Asian patients,^9,10 poses a significant challenge in maintaining IIA patency. Herein is described the use of an IBD in a patient with an infrarenal AAA and short CIA anatomy.

Case Report

A 74-year-old man of Asian ethnicity was diagnosed with an asymptomatic infrarenal AAA as an incidental finding while undergoing cardiac investigation. Past history included hypertension, hypercholesterolemia, past smoking, and a family history of aortic aneurysm. Computed tomography angiography (CTA) demonstrated a 67-mm fusiform infrarenal AAA (Figure 1, A and B). The right CIA was funnel-shaped, measuring 14 to 22 mm in diameter and only 15 mm in length, providing no appropriate stent-graft landing zone. The left CIA measured 14 mm in diameter and 25 mm in length. It was decided to try to preserve flow to both IIAs using a Gore Iliac Branch Endoprosthesis (W. L. Gore & Associates, Flagstaff, AZ, USA) for the short right CIA and a conventional limb to land in the left CIA.

OPEN IN VIEWER

Figure 1.

Preoperative computed tomography (CT) reconstruction (A) and sagittal view (B); a indicates the short right common iliac artery, b is the right internal iliac artery, and c is the right external iliac artery. (C) Intraoperative completion angiogram after deployment of the iliac branch endograft (a is the right external iliac artery, b is the right internal iliac artery, and c is the aortic bifurcation). (D) The follow-up CT scan at 6 months shows patent external and internal iliac arteries.

The procedure was performed using percutaneous access to both common femoral arteries (CFAs). The 23-×12-mm IBD was inserted via the right groin and positioned with the main body of the IBD well into the aortic aneurysm. Through-and-through wire access from the left CFA was established, and a 12-F sheath was passed from the left CFA into the IIA limb of the IBD. The right IIA was accessed and the 16/10-×70-mm branch graft deployed. The external iliac limb was then fully deployed. The main aortic device (23-×14.5-×120-mm Excluder; W. L. Gore & Associates) was inserted via the left groin and partially deployed. The contralateral limb was cannulated through the iliac branch graft and the bridging limb deployed. The ipsilateral limb of the main aortic graft was then fully deployed and the left limb extended to the iliac bifurcation after localization of the IIA origin. Completion imaging (Figure 1C) showed good positioning of the graft with no evidence of endoleak and patency to both IIAs. The patient was discharged from hospital, and early follow-up CTA at 6 weeks showed patency of the endograft and both IIAs. Further follow-up at 6 months (Figure 1D), 12 months, and 24 months documented ongoing patency of the IBE and IIA limb and exclusion of the aortic aneurysm.

Discussion

The short CIA poses significant challenges in EVAR, frequently requiring sacrifice of the IIA on the affected side. The short CIA is a recognized anatomical variant, particularly in the Asian population,^9,10 and has sometimes led to open aneurysm repair rather than EVAR, with the known increase in procedural mortality and morbidity. A study by Cheng et al ¹⁰ found that CIA length in an Asian population was significantly shorter than their Western counterparts. The mean right and left CIA lengths were 29.9 and 34.2 mm, respectively, whereas most Western series reported CIA lengths in excess of 50 mm. ¹¹ The average maximum diameter of the CIA was also significantly larger in Asians at 20.2 mm for the right and 17.9 mm for the left CIA compared with the Western series. Review of the patients in these studies found that IIA coverage with or without embolization would be necessary in 51% of endovascular repairs due to short and/or aneurysmal CIAs.

In the case presented here, the Gore IBD was deployed within the AAA itself and cannulated from the contralateral femoral artery. Although this application is not within the device’s Instructions for Use (IFU), the design of this graft facilitated this approach due to its larger proximal diameter (23 mm) and flexibility, allowing it to “flex” to the side of the contralateral cannulation. It may be possible to achieve a similar end result with other branched devices; however, this would generally require access from the upper limb in order to enter the IIA. This third access site would add further complexity to the procedure and may not be possible in some patients due to the aortic arch anatomy or other vascular issues.

The funnel shape of the CIA allowed deployment of the IBD within the AAA sac while still maintaining access to the ipsilateral IIA. A “narrow” origin to the target CIA could limit the IIA access, with the IBD limb opening in the aneurysm sac. This must be part of the case planning. In our experience, however, the short CIA anatomy is usually associated with a funnel shape and so is favorable to maintaining access to the IIA.

One limiting factor to using the IBD in this form of anatomy is the length of the currently available bridging component. An adequate length from the lowest renal artery to the IIA on the side to be treated is crucial if both the IBD and main aortic stent-graft body are to be deployed and still have a gap for the bridging graft. The shortest bridging piece currently available (100 mm) means a minimum 150 to 160 mm renal to IIA length allowing ~40 mm of separation between the main aortic graft and the IBD. This can be reduced with concertinaing of the bridging graft to a certain extent, as was done in this case. A crossed-limb configuration may also provide some ability to treat shorter renal-IIA length anatomy. A shorter bridging limb (eg, 80 mm) would increase the applicability of the IBD for IIA preservation in patients with short CIA anatomy. This length would maintain good overlap into the contralateral stump of the main aortic graft and the main body of the IBD, with enough separation to allow cannulation of the iliac stump on the main aortic graft.

Conclusion

This case demonstrates the feasibility of using the Gore IBD to treat patients with short CIA anatomy while preserving flow to the ipsilateral IIA with maintained early patency of the IIA limb. The use of the device in this way is not part of the manufacturer’s IFU, and familiarity using the device within the IFU is recommended before attempting off label, complex cases such as this. The use of the graft to preserve IIA patency could have significant implications to expand the use of EVAR in patients with short CIAs. A shorter bridging piece than is currently commercially available would increase the applicability of this technique.