Common iliac artery aneurysms (CIAAs) are concomitant in a significant proportion of patients with abdominal aortic aneurysm (AAA), accounting for 20%-40% of cases [1,2]. Traditional endovascular treatment of these aneurysms involves internal iliac artery (IIA) embolization and stent graft extension to the external iliac artery (EIA) to achieve adequate distal sealing and prevent type II endoleaks from the IIA. However, although still controversial, IIA embolization may not be a benign procedure considering the reported rates of buttock claudication and erectile dysfunction caused by the interruption of blood flow to the pelvic organs [3].

The iliac branch device (IBD) is now widely used to prevent these complications. A recent large-scale study and meta-analysis of IBD outcomes reported that the risk of late failure of IBD is low [4,5], and the reintervention rate does not differ from that of simple endovascular aneurysm repair (EVAR) without IBD among patients with AAA [5]. Also, the rate of IBD-related endoleaks during follow-up was reported as 2.1%-2.3% in large-scale series, and most IBD-related endoleaks were successfully treated endovascularly [6]. Therefore, recent guidelines recommend using an IBD to maintain perfusion in anatomically suitable patients [7,8]. However, in the domestic market, only one type of IBD and balloon-expandible bridging stent graft for IIA is currently available. In addition, the combination of the Zenith branch iliac endovascular graft (ZBIS; Cook Medical) and LifeStream (Bard Peripheral Vascular) balloon-expandable stent graft (BESG) currently used in South Korea has not been widely used or investigated in other countries. Here we present two cases of type Ic endoleak after IBD placement with caution. This study was approved by the Institutional Review Board of Kyungpook National University Chilgok Hospital (IRB no. 2023-01-009), which waived the requirement for written informed consent.

1) Case 1

An 83-year-old man presented with a 4-hour history of abdominal pain. Computed tomography (CT) performed at another medical center revealed an AAA with concomitant CIAAs. The maximum AAA diameter was 53 mm. The CIAAs were bilateral, with maximal diameters of 65 mm and 47 mm on the right and left sides, respectively (Fig. 1). The patient also had chronic obstructive pulmonary disease and mild cognitive dysfunction. A physical examination revealed a palpable pulsating abdominal mass, and he complained of tenderness in the right side of his abdomen. Based on his age and associated comorbidities, we decided to perform EVAR. Additionally, IBD placement on the right and IIA embolization on the left were planned to avoid bilateral disruption of pelvic flow since the maximal diameter of the left IIA was greater than that of the right IIA. Measurements made using three-dimensional imaging software (Aquarius iNtuition; TeraRecon Inc.) revealed that the diameters of the right EIA and proximal IIA were 10.9 mm and 10.8 mm, respectively. Moreover, the right CIAA was 72 mm long, while the right iliac bifurcation was 20 mm in diameter. More detailed information about the anatomy for the IBD placement is summarized in Fig. 1.

Figure 1. Initial computed tomography angiography (CTA) scan. (A) Detailed anatomy of bilateral iliac arteries was presented and the axial image of CTA demonstrated bilateral common iliac artery aneurysms (CIAAs) measuring 65 mm on the right side and 47 mm on the left side. (B) A three-dimensional reconstruction image revealed an abdominal aortic aneurysm with bilateral CIAAs. CIA, common iliac artery; L, length; IIA, internal iliac artery; D, diameter; EIA, external iliac artery; A, angle.

Standard operating procedures were followed for all techniques. The bilateral common femoral arteries were punctured under general anesthesia, and vascular closure devices (Perclose ProGlide; Abbott Vascular) were placed. The left proximal IIA was embolized using multiple detachable coils. The IBD (ZBIS-12-45-41) was then advanced from the right groin, and a through-and-through wire was subsequently created. After selecting the right IIA from the contralateral femoral sheath using the up-and-over technique, a 10 mm×58 mm LifeStream BESG was deployed as a bridging stent graft for the ZBIS and the right IIA. Given that the IIA was 10.8 mm in diameter at the time of measurement, we performed additional balloon flaring of the distal part of LifeStream using a 12 mm×20 mm Admiral balloon (Medtronic Cardiovascular) (Fig. 2A). Notably, angiography performed after full deployment of the ZBIS and LifeStream did not reveal an Ic endoleak (Fig. 2B). The remaining procedures, including main body deployment, contralateral gate selection, deployment of a bridging stent graft for the main body and ZBIS, and ipsilateral limb extension to the left EIA were performed without any notable adverse events. Angiography performed upon completion of the procedure revealed no type I, III, or IBD-related endoleaks. The postoperative course was uneventful, and the patient was discharged 4 days postoperatively.

Figure 2. Intraoperative images during the deployment of the iliac branch device (IBD) and bridging stent graft. (A) The distal edge of the 10 mm×58 mm LifeStream BESG was over-dilated with a 12 mm×20 mm balloon to secure the distal sealing zone. (B) Angiography performed after placement of the IBD and LifeStream demonstrated no type Ic endoleaks intraoperatively.

One month after the EVAR, a follow-up CT scan revealed an endoleak adjacent to the IBD; a type Ic endoleak was suspected (Fig. 3A). As the diameters of the AAA and CIAA sacs remained stable, the patient was followed up with the expectation of spontaneous resolution. However, CT angiography (CTA) performed at 1-year post-EVAR revealed a sustained type Ic endoleak, and the right CIAA sac diameter increased to 68 mm (Fig. 3B); therefore, we decided to perform reintervention. Under local anesthesia, the proximal brachial approach was undertaken with cutdown, and an 8-F Shuttle sheath (Cook Medical) was placed on the right bridging stent graft to the IIA. At this time, an angiography-confirmed type Ic endoleak (Fig. 3C) and an additional 10 mm×58 mm LifeStream was deployed 2 cm distal to the previous end of the LifeStream. Finally, the LifeStream was dilated with a 12 mm×20 mm balloon. Angiography performed after the procedure revealed dissection of the IIA at the distal end of the LifeStream, but no endoleak was observed in the CIAA sac (Fig. 3D). Follow-up CTA performed 1 month after the reintervention demonstrated no type Ic endoleaks (Fig. 3E).

Figure 3. Follow-up computed tomography angiography (CTA) and intraoperative images during reintervention. (A) After one month of operation, a 3-dimensional (3D) reconstruction CTA image revealed that a perigraft endoleak (arrow) from the distal edge of the iliac artery stent graft had extended to the abdominal aortic aneurysm (AAA) sac. (B) The sustained type Ic endoleak (arrow) was also demonstrated by the 3D reconstruction image at 1 year postoperative, but the extension to the AAA sac disappeared. (C) Angiography scan during reintervention confirmed the type Ic endoleak (arrow) to the right common iliac artery aneurysm (CIAA) sac. (D) After the placement of additional LifeStream distal to the previous stent graft, the type Ic endoleak to CIAA disappeared, but dissection occurred (arrow). (E) Follow-up CTA performed 1 month after reintervention demonstrated no type Ic endoleak.

2) Case 2

An 88-year-old man presented with abdominal discomfort for which follow-up imaging revealed an increased AAA diameter. Four years prior, he was diagnosed with AAA with a diameter of 42 mm on a CT scan. However, the patient did not undergo any subsequent follow-up imaging examinations; rather he presented to our hospital upon developing abdominal discomfort. His AAA was 67 mm in diameter at this presentation; in addition, concomitant bilateral CIAAs (32 and 40 mm on the right and left, respectively) were present. A preoperative evaluation of his cardiac and pulmonary functions revealed an acceptable risk for surgery; moreover, he did not report the presence of any other medical conditions. Similar to the previous case, IBD in the right iliac artery and embolization of the left IIA were planned to preserve at least one pelvic flow because the left EIA demonstrated severe tortuosity compared with the right EIA. An anatomical examination of the right iliac artery revealed the following: common iliac artery (CIA) length, 64 mm; iliac bifurcation diameter, 16 mm; proximal EIA diameter, 9.2 mm; and maximal proximal IIA diameter, 9.9 mm. Fig. 4 summarizes the anatomy of both iliac arteries.

Figure 4. Preoperative computed tomography angiography (CTA) scan of the second patient. (A) Detailed anatomy of bilateral iliac arteries was presented and the proximal right internal iliac artery showed a diameter of 9.2-9.9 mm on measurement. (B) An abdominal aortic aneurysm with bilateral common iliac artery aneurysms were demonstrated by a three-dimensional reconstruction image. CIA, common iliac artery; L, length; IIA, internal iliac artery; D, diameter; EIA, external iliac artery; A, angle.

First, the left proximal IIA was embolized with multiple detachable coils; subsequently, the IBD (ZBIS-10-45-41) was delivered to the right CIA and the bridging stent graft deployed to the IIA (10 mm×58 mm LifeStream). The remaining procedures were performed as usual, including deployment of the main body, and bridging stent graft for main body and IBD. However, given the tortuous course of the left EIA, a left limb extension was performed using an Endurant IIs iliac extender (Medtronic Cardiovascular) with a distal diameter of 10 mm, while a 12 mm×40 mm self-expanding stent (Protégé; Medtronic Cardiovascular) was deployed to prevent kinking at the distal end of the stent graft. An angiography scan after the procedure suggested an endoleak; however, we considered it a type IV endoleak and decided to follow the patient.

A type Ic endoleak around the IBD extending to the AAA sac was observed on CTA 1 month postoperative (Fig. 5A, B). We decided to perform a reintervention because the aneurysm was pulsatile on physical examination and deemed significant on contrast-enhanced ultrasonography. Initially, we performed balloon dilation of the previously placed LifeStream with a 12 mm×20 mm Admiral balloon to facilitate additional attachment to the IIA, but the endoleak persisted. Therefore, an additional 10 mm×58 mm LifeStream was advanced and deployed distal to the previous stent graft. Subsequently, a 12-mm balloon inflation was performed. The type Ic endoleak had disappeared on the angiography scan performed at the completion of the operation. During the 6-month follow-up, the AAA sac remained stable with no recurrent type Ic endoleaks (Fig. 5C).

Figure 5. Follow-up computed tomography angiography (CTA) images at 1 month postoperative and 6 months post-reintervention. (A) The perigraft endoleak at the internal iliac artery and common iliac artery aneurysm sac (arrows) was demonstrated by CTA axial image. (B) Type Ic endoleak (arrows) extending to the abdominal aortic aneurysm sac was revealed by a three-dimensional (3D) CTA reconstruction image. (C) Type Ic endoleak was disappeared by a 3D CTA reconstruction image after 6 months of reintervention.

The use of IBD to prevent bilateral interruption of pelvic flow whenever possible, particularly for patients with bilateral CIAAs with suitable anatomy, has been advocated by recent guidelines [7,8]. A recent report by the pELVIS registry on the outcomes of IBD indicated that IBD is associated with highly positive outcomes, with 95.1% primary patency and 78.2% freedom from IBD-related reintervention at 72 months [5]. Additionally, the risk of late IBD failure was low, while the reintervention rates were comparable to those of EVAR without IBD [5].

Although the reported outcomes of IBD were mainly been positive and long-lasting, we observed two cases of IBD-related reintervention caused by type Ic endoleak among 22 cases of IBD placement over 5 years. This finding highlights the importance of following instructions for use (IFU) when planning IBD and strict follow-up after IBD placement. Notably, the basic anatomical criteria of the ZBIS are as follows: EIA length, >20 mm; EIA diameter, 8-11 mm; IIA length, >10 mm; IIA diameter, 6-9 mm; and CIA length, >50 mm. Moreover, the ZBIS IFU suggest a BESG for a bridging stent graft to the IIA. In studies from Western countries, several types of BESGs, including Advanta-covered stents (Atrium Medical), Fluency stent graft (Bard Peripheral Vascular), and BeGraft (Bentley Innomed) were used as bridging stent grafts for IIA [4,5,9]. However, at present, the only domestically applicable BESG is LifeStream, which is composed of a stainless-steel strut encased between two layers of expanded polytetrafluoroethylene fabrics.

We had no choice but to use the 10-mm diameter LifeStream because the 12-mm diameter LifeStream was not available in Korea at the time of the procedure. Notably, the ability of the 10-mm LifeStream to expand to 12 mm after over-dilation with a 12-mm balloon is an advantage despite the inevitable shortening. Therefore, although not mentioned in the IFU, it can be assumed that LifeStream BESG is useful for patients with slightly larger IIA than that mentioned in basic IFU, as in our cases; notably, the diameters of IIA were 10.8 mm and 9.9 mm in the first and second cases, respectively. Globally, the use of LifeStream as a bridging stent graft to the IIA has not yet become widespread. In a preliminary multicenter study from the Korean registry that used LifeStream as a bridging stent graft [10], the rate of technical failure was 23.7% (9/38), with type Ic endoleaks accounting for two-thirds (6/9) of the causes. In this multicenter series, 23.7% of aneurysms had a maximal IIA diameter of >12 mm. This may have caused the high rate of type Ic endoleaks observed in our cases.

The causes of the type Ic endoleaks in our study should be considered and discussed. First, a minor endoleak from the distal edge of the LifeStream may not have been detected intraoperatively. The amount of endoleaks may have increased and become readily visible on CTA. At the time of IBD placement, we used a mobile C-arm but did not confirm the definitive endoleak via angiography. However, endoleaks can go unnoticed because of limited C-arm quality. In the second case, there was an endoleak at the right CIAA sac, but we considered it a type IV. Despite this, the length of the IIA sealing zone on the 1-month follow-up CTA was not short, measuring 24 mm in the first case and 27 mm in the second case. Second, endoleaks can be caused by the postoperative recoil of the stent graft. Despite the results of a previous ex vivo study [11], in a study on over-dilation, in which the mechanical properties of LifeStream, Atrium iCAST (Maquet Cetinge Group), and Viabahn VBX stents (W. L. Gore & Associates) were investigated, the LifeStream had the greatest potential for overstretching. Nevertheless, it was associated with higher recoil rates than other BESGs. In a single-center study of the LifeStream with fenestrated and branched thoracoabdominal endovascular repair, perifenestration endoleaks secondary to inadequate sealing were observed in 22% of fenestrations [12]. The authors suspected that the cause of the endoleak was recoil due to insufficient radial force [12]. In our cases, embolization of the IIA branches and stent graft extension to a more distal IIA may be preferable treatment options. Nevertheless, the distal IIA after its branching typically has tortuosity, and the use of BESGs is considered difficult and inappropriate owing to the kinking. A recent report comparing the outcomes of hypogastric BESG and self-expanding stent graft (SESG) as a bridging stent graft to IIA revealed no statistically significant differences in clinical outcomes between patients who underwent hypogastric BESG and SESG [5]. Therefore, in ectatic or aneurysmal IIA, branch embolization with SESG extension to the distal IIA after branching could be an option. Third, the progression of IIA disease may be suspected. However, an endoleak was detected 1 month after EVAR via CTA. Thus, the likelihood of disease progression is reduced.

Currently, the major anatomic limitation of IBD in East Asians is the unsuitability of the IIA diameter for the placement of bridging stent grafts. In studies involving Asian patients, a reported 9.8% of Chinese and 17.0% of Japanese patients are anatomically suitable according to the basic ZBIS IFU [13,14]. Among the reasons for anatomic exclusion for basic ZBIS IFU, the most common was an IIA diameter of <6 mm or >9 mm. Accordingly, 78% of Chinese and 47% of Japanese patients were excluded from the basic IFU [13,14]. Thus, for the successful placement of IBD in Korean patients, a further analysis of the anatomy of aortoiliac aneurysms and isolated CIAA among Korean patients is required along with the introduction of an additional usable device, research, and follow-up.

In summary, here we described two cases of type Ic endoleak after IBD placement in conjunction with over-dilation of the distal LifeStream as a bridging stent graft to IIA, in which the diameter of the IIA was slightly larger than that mentioned in the basic IFU. Therefore, IBD placement should be performed with caution in such cases, and accurate preoperative evaluation and intraoperative manipulation are essential.

None.

Hyung-Kee Kim has been the editor-in-chief of the VSI since 2023. He was not involved in the review process. Otherwise, no potential conflict of interest relevant to this article was reported.

Conception and design: WSY, HKK. Analysis and interpretation: all authors. Data collection: all authors. Writing the article: HJK, HKK. Critical revision of the article: WSY, HKK. Final approval of the article: all authors. Overall responsibility: HKK.