Minimally Invasive Management of Aortoiliac Aneurysms: Outcomes in 12 Patients with Iliac Branch Endografts

Introduction

Common iliac artery aneurysms account for approximately 2% of all aneurysms. They are often associated with abdominal aortic aneurysms and typically measure between 1 and 2 cm in diameter (mean 1.53 cm; range 0.7–2.35 cm). These aneurysms are also more commonly found on the right side than on the left [1].

Endovascular aneurysm repair (EVAR) is currently the option for most patients with abdominal aortic aneurysm [2–6]. Initially reserved for patients at high surgical risk, EVAR has been increasingly chosen by many authors, even for those patients with low surgical risk, provided that the morphology of the aneurysm is suitable for the procedure [5]. Successful EVAR excludes the aneurysm from blood flow by placing a bifurcated stent graft, which is typically inserted through the femoral arteries. Initially, femoral artery access for EVAR was achieved via surgical cutdown. However, with advancements in percutaneous arterial closure devices, percutaneous EVAR has become more common, and bilateral percutaneous access is now used in most cases [4]. EVAR has advantages for elderly patients; however, technical challenges and outcomes in this age group vary [4].

One of the major limitations of EVAR arises when the aneurysm involves one or both common iliac artery bifurcations. In such cases, excluding the aneurysmal sac often requires the occlusion of the hypogastric arteries, typically achieved through pre-embolization [5]. Their effectiveness in treating the internal iliac artery has not yet been demonstrated in comparing internal iliac artery revascularization with internal iliac artery occlusion in the endovascular treatment of aorto-iliac aneurysms or isolated iliac aneurysms involving the iliac bifurcation [7]; however, it is effective in the treatments of abdominal aortic aneurysms [8].

Unfortunately, hypogastric artery occlusion can lead to complications related to pelvic ischemia, such as gluteal claudication, sexual dysfunction, and, in some instances, colonic ischemia. These complications are well documented in scientific literature and can significantly affect patient quality of life [5,6,9].

To prevent these complications, 2 primary approaches can be taken. The first approach is direct surgical reconstruction, which is more invasive. The second approach, which is more innovative and less invasive, involves the use of new endovascular devices. These devices have been specifically designed to preserve hypogastric artery patency without requiring its occlusion [10,11]. In recent years, iliac branch devices have been developed to ensure continuous blood flow to the hypogastric artery during aneurysm exclusion [10,11], with studies showing very satisfactory efficacy and survival rates [12].

In this report, we aimed to describe the management and outcomes in 12 patients, aged 62 to 83 years, with endovascular repair of aorto-iliac aneurysms using iliac branch stent grafts.

Material and Methods

COMPOSITION AND CLINICAL CHARACTERISTICS OF THE POPULATION:

Between January 2002 and June 2011, 12 patients (8 men, 4 women) aged between 62 and 83 years were treated for aorto-iliac aneurysms. Of these patients, 3 presented with isolated bilateral iliac aneurysms, 7 had aorto-iliac aneurysms involving both iliac bifurcations, and in 2 cases, the hypogastric artery was also involved. The remaining 2 patients had previously undergone aorto-iliac bypass graft implantation and developed bilateral iliac aneurysms (Table 1).

The cohort exhibited significant comorbidities, with 8 patients having hypertension or coronary artery disease, 3 having diabetes mellitus or chronic obstructive pulmonary disease, and 1 patient having end-stage renal disease. Given their overall high surgical risk (American Society of Anesthesiologists classes 3 and 4), these patients were deemed unfit for open surgical repair.

All patients underwent preoperative volume rendering computed tomography (CT) scan angiography. The average diameter of the aortic aneurysms was 54 mm (ranging from 48 to 66 mm), while the mean size of the iliac aneurysms was 36 mm (ranging from 25 to 61 mm). All patients had patent hypogastric arteries, and in 5 cases, the inferior mesenteric artery was occluded (including 2 cases of prior aortic bypass grafts). Two patients also had large hypogastric aneurysms. Six patients, experiencing erectile dysfunction, underwent preoperative ultrasound evaluation of penile blood flow, revealing pathologic Doppler waveform modifications.

TREATMENT MODALITIES AND TECHNIQUES:

Eleven patients were treated with unilateral internal iliac artery branch devices combined with a proximal bifurcated endograft (Cook, Inc, Bloomington, IN, USA). In 10 patients, hypogastric artery embolization, side branch placement, and aortic bifurcated endograft implantation were performed in a single surgical session. In 1 patient, hypogastric embolization was performed 1 month prior to the endograft deployment. To bridge the gap between the side branch and the hypogastric artery and ensure proper sealing, covered stents – Advanta V12 (Atrium Medical, Hudson, NH, USA) in 10 patients, and Fluency (CR Bard Inc, Murray Hill, NJ, USA) in 1 patient – were used. Internal iliac artery embolization was performed using Amplatzer vascular plugs (AGA Medical, Golden Valley, MN, USA) in 2 patients, and platinum fibered coils in 10 patients. A pig-tail diagnostic catheter was introduced through the left axillary artery in all cases.

During the early stages of the study, when bifurcated standard endografts were not yet available, 1 patient was treated with a custom-made Zenith endograft (Cook Inc). In this case, the left hypogastric artery was embolized using platinum fibered coils, followed by the insertion of a common-external iliac leg excluder endograft (WL Gore & Associates, Flagstaff, AZ, USA). Three months later, the contralateral iliac aneurysm was treated with a custom-made branched endograft. This bifurcated iliac component consisted of a common iliac trunk, a short cuff for the internal iliac artery, and the external iliac limb. Using an ipsilateral femoral approach, the iliac bifurcated component was introduced. The radiopaque marker indicating the short limb was placed just above the hypogastric artery, allowing for the endograft’s release. Subsequently, via the contralateral common femoral artery using a cross-over-sheath, the short limb and internal iliac artery were cannulated using a guidewire. All procedures were performed under epidural anesthesia.

Results

IMMEDIATE RESULTS:

No perioperative deaths were observed. At the end of the procedure, left iliac graft limb and iliac branch occlusion were detected in 1 patient. In spite of several attempts, a good recanalization was not possible, probably due to an inadequate deployment of iliac side branch, and a femoro-femoral crossover bypass graft was needed.

FOLLOW-UP RESULTS:

During the follow-up (6 months to 7 years, mean 36 months) postoperative CT scans showed good aneurysms exclusion and hypogastric branch patency in 11 patients (Figure 1); in 4 patients, it also detected a type II endoleak from lumbar arteries that resolved spontaneously during follow-up, as demonstrated by echo-enhanced duplex ultrasound scanning (CEUS) 6 and 12 months later. In the patient who required a femoro-femoral bypass graft, CT scanning and CEUS controls revealed good exclusion of the aneurysm and the patency of the extra anatomical graft (Figure 2). This patient reported erectile dysfunction and mild buttock claudication at 30 days from discharge (Table 2).

Discussion

When treating aorto-iliac aneurysms, either through open or endovascular surgery, preserving or revascularizing at least 1 hypogastric artery is crucial to prevent postoperative complications, such as impotence, buttock claudication, colonic ischemia, and gluteal necrosis [13,14]. In our prior experience with open surgical treatments, we aimed to preserve hypogastric perfusion by performing the distal anastomosis at the iliac bifurcation. Alternatively, we performed bypass grafts on the hypogastric artery, or, in select cases, an end-to-side anastomosis on the external iliac artery to ensure retrograde blood flow, while sewing the aneurysmal sac over the iliac bifurcation. However, extensive dissection is often required in these surgeries, potentially causing hypogastric plexus injuries, which can negate the benefits of hypogastric revascularization in preserving erectile function [15,16].

When EVAR is indicated, pelvic blood flow can be preserved by using hybrid procedures. These involve the endovascular exclusion of the iliac bifurcation aneurysm, coupled with surgical revascularization of the distal hypogastric artery [14]. However, this approach carries the risk of neurological complications, which are more common in patients with prior aorto-iliac surgeries.

An alternative solution for maintaining hypogastric artery patency is the use of iliac side-branched endografts. These devices allow for the exclusion of the iliac aneurysm while ensuring the revascularization of at least 1 hypogastric artery [13,14,17–19]. This option is suitable for safeguarding pelvic blood flow when collateral pathways, such as those involved in atherosclerotic disease, are compromised or absent. Presently, this revascularization can be conducted by an endovascular exclusion of the iliac aneurysm and a branched endograft insertion to save the patency of a single or both hypogastric arteries [10,20].

On the other hand, the preservation of only a single hypogastric artery involves the embolization of the contralateral one by means of platinum coils or occluder systems.

The successful application of these procedures requires accurate preoperative assessment of vessel anatomy, including their length, diameter, and any unique anatomical features. Operator skill is also essential, as these procedures are technically more demanding than standard EVAR techniques. Additionally, this approach is not feasible in patients with hypogastric artery aneurysms.

In our experience, we achieved favorable results regarding aneurysm exclusion and vessel patency in the 10 patients treated in a single surgical session and in the 1 patient who underwent prior hypogastric embolization. No major postoperative complications were observed in this group. In only 1 case, an acute thrombosis occurred in the left iliac and hypogastric limbs, likely due to improper endograft deployment. Actually, obstructive complications can occur from mistakes in short limb orientation and subsequent difficulties in internal iliac artery intubation, or from a wrong covered stent graft release.

We did not observe buttock embolization during our endovascular procedures. This complication is rare but has occurred in our open surgery cases, particularly when treating large aneurysms with an intraluminal thrombus.

For patients with bilateral iliac aneurysms, modular multi-branched devices can be used to preserve both hypogastric arteries. According to the experience of Abraham et al [21], this procedure is now considered routine and is not significantly more complex or time-consuming than hypogastric embolization. However, in our opinion, preserving just one hypogastric artery reduces radiation exposure and operative time and improves cost-effectiveness.

Additionally, Itoga et al [22] reported that EVAR was safe for treating common iliac artery aneurysms in a cohort of 69 Japanese patients, with a low incidence of persistent buttock claudication (only 1 case) and no major pelvic complications. Furthermore, Khouri et al [23] evaluated the use of fenestrated/branched endovascular aortic repair in a retrospective analysis of data from the US Aortic Research Consortium, demonstrating low 30-day mortality rates.

Postoperative follow-up should include CEUS before discharge, followed by another CEUS at 30 days. Additionally, CT angiography should be performed at 30 days and again at 6 months, to ensure ongoing patency and aneurysm exclusion [21].

In reference to the limitations of our study, they are mainly related to being a case series: the absence of a control group and the small case series can limit its reproducibility and generalization.

Conclusions

Our results indicate that using iliac side-branch endografts to treat iliac aneurysms is a feasible approach with generally good outcomes. However, several important challenges persist. These include the high cost of the procedure, the need for careful preoperative planning, and the requirement for advanced technical expertise. For these reasons, the procedure is best performed in specialized centers with the necessary experience and resources.