Outcomes of the Gore Excluder Iliac Branch Endoprosthesis Using Division Branches of the Internal Iliac Artery as Distal Landing Zones

Abstract

Purpose: To evaluate the outcomes of the Gore Excluder Iliac Branch Endoprosthesis (IBE) using division branches of the internal iliac artery (IIA) as distal landing zones. Materials and Methods: Between January 1, 2014, and December 31, 2018, 74 patients (mean age 74±7 years; 72 men) treated for aortoiliac or common iliac artery aneurysms had an IBE deployed with distal landing of the side branch within the main trunk (n=60) of the internal iliac artery (IIA) vs within a division branch (n=25). Thirteen (17%) patients received bilateral IBE implantations for a total of 85 vessels evaluated. Early endpoints were technical success, 30-day mortality, 30-day major adverse events (MAEs), and 30-day major access complications. Late endpoints were survival, primary and secondary IIA patency, freedom from IIA branch instability, freedom from new-onset buttock claudication, and aneurysm sac diameter changes. Time-dependent outcomes were reported as Kaplan-Meier curves with differences assessed using the log-rank test. Estimates are presented with the 95% confidence interval (CI). Results: The overall technical success rate was 97%, with 1 technical failure per group (p=0.43). Two patients, one from each group, died within 30 days (p=0.43). No significant differences were seen in the rates of 30-day MAEs (7% vs 17%, p=0.35) or major access complications (9% vs 11%, p>0.99) for patients receiving distal landing in the main trunk vs a division branch, respectively. The mean follow-up for the entire cohort was 19±12 months. The overall 1-year survival rate was 94% (95% CI 74% to 99%). The primary and secondary patency rates at 1 year were 98% (95% CI 88% to 99%) vs 95% (95% CI 72% to 99%, p=0.72) and 98% (95% CI 88% to 99%) vs 100% (p=0.41) for the main trunk vs division branch groups, respectively. Freedom from IIA branch instability estimates were also similar at 1-year follow-up [93% (95% CI 82% to 97%) vs 90% (95% CI 66% to 97%), p=0.29], as were the freedom from new-onset buttock claudication estimates [98% (95% CI 86% to 99%) and 94% (95% CI 67% to 99%), respectively; p=0.62]. Mean sac diameter change was 5.4±5.3 mm, not significantly different between the groups (p=0.85). Conclusion: Use of the posterior or anterior division of the IIA as a distal landing zone for the Gore Excluder IBE was safe and efficacious in the midterm. This technique may permit extending indications for endovascular repair of aortoiliac aneurysms to cases with unsuitable anatomy within the IIA main trunk. Long-term assessment is needed to affirm the efficacy of this technique.

Keywords

aortoiliac aneurysms distal landing zone endovascular aneurysm repair iliac branch devices internal iliac artery

Introduction

Iliac branch devices (IBDs) currently represent the first-line endovascular option to preserve antegrade flow to the internal iliac artery (IIA), when anatomically feasible, in patients with aortoiliac aneurysms. This has revolutionized endovascular aneurysm repair (EVAR), now allowing total endovascular incorporation of the IIA in most cases.^1,2 The Gore Excluder Iliac Branch Endoprosthesis (IBE; Gore Medical, Flagstaff, AZ, USA) has been approved in Europe (2013) and the United States (2016) for treatment of common iliac artery (CIA) and aortoiliac aneurysms.^1,3,4

One common limitation of IBD applicability is an inadequate distal landing zone due to coexisting IIA aneurysm or poor quality of the IIA main trunk. Consequently, one option is to create a suitable landing zone in the distal normal IIA or one of its branches in the presence of diseased or ectatic IIAs. However, outcomes of this technique are limited. The aim of the study was to evaluate the short- and midterm outcomes of the Gore Excluder IBE using the division branches of the IIA as distal landing zones.

Materials and Methods

Study Design and Patient Sample

A search of the electronic medical records identified all consecutive patients electively treated for aortoiliac or CIA aneurysms using Gore Excluder IBEs between January 1, 2014, and December 31, 2018. Patients with <1 month of follow-up and/or lack of available imaging follow-up were excluded. The search identified 74 patients (mean age 74±7 years; 72 men) suitable for this retrospective analysis. Thirteen (17%) patients had received bilateral IBE implantations. Of these, 6 were in the main trunks on each side, 5 were in a division branch on each side, and the last 2 patients received one in each location. Patients were dichotomized according to the successfully completed distal landing sites for the IBD (60 main trunks of the IIA or 25 division branches).

The clinical and imaging data were reviewed for baseline demographics, comorbidities, and anatomical characteristics as well as procedure details and outcomes. Baseline patient characteristics are given in Table 1. The study was approved by the Institutional Review Board of the Mayo Clinic (Rochester, MN, USA; approval number 18-010874). All patients consented to participation in minimal-risk research studies.

Table 1.

Baseline Demographics, Comorbidities, and Anatomical Characteristics.^a

Variable	Overall (n=74)	Main Trunk (n=56)	Division Branch (n=18)	p
Demographics and comorbidities
Age, y	74±7	74±7	75±7	0.47
> 80 years	17 (23)	15 (25)	2 (15)	0.72
Men	72 (97)	59 (97)	13 (100)	>0.99
Body mass index, kg/m²	29±5	29±5	28±5	0.42
Cigarette smoking	36 (49)	30 (49)	6 (46)	>0.99
Hypertension	64 (86)	51 (84)	13 (100)	0.19
Hypercholesterolemia	61 (82)	50 (82)	11 (85)	>0.99
Coronary artery disease	33 (45)	29 (48)	4 (31)	0.36
COPD	18 (24)	13 (21)	5 (38)	0.28
Peripheral artery disease	8 (11)	6 (10)	2 (15)	0.62
CKD stage III-V	18 (24)	14 (23)	4 (31)	0.72
Diabetes mellitus	8 (11)	7 (11)	1 (8)	>0.99
Congestive heart failure	12 (16)	11 (18)	1 (8)	0.68
Stroke/TIA	7 (9)	7 (11)	0 (0)	0.34
Preoperative evaluation
Serum creatinine, mg/dL	1.1±0.4	1.1±0.5	1.0±0.3	0.18
eGFR, mL/min/1.73 m²	80±29	79±26	86±37	0.77
Prior aortic repair	17 (23)	14 (23)	3 (23)	>0.99
EVAR	9 (12)	7 (11)	2 (15)	0.65
F/BEVAR	3 (4)	3 (5)	0	>0.99
Surgical grafts	5 (7)	4 (7)	1 (8)	0.88
Up and over technique	14 (19)	11 (18)	3 (23)	0.70
Anatomical measurements of the IBE side, mm
Largest aortic diameter	48±16	47±18	51±10	0.12
Maximum CIA diameter	37±10	35±8	41±13	0.07
Maximum IIA diameter	19±12	17±11	23±15	0.04
Aortic bifurcation diameter	36±11	35±11	39±9	0.01

Abbreviations: CIA, common iliac artery; CKD, chronic kidney disease; COPD, chronic obstructive pulmonary disease; eGFR, estimated glomerular filtration rate; EVAR, endovascular aneurysm repair; F/BEVAR, fenestrated/branched EVAR; IBE, iliac branch endoprosthesis; IIA, internal iliac artery; TIA, transient ischemic attack.

Continuous data are presented as the mean ± standard deviation; categorical data are given as the number (percentage).

Device Description

The Gore Excluder IBE is made up of 2 components. The main iliac branch component is an IBD with a proximal diameter of 23 mm and overall length of 10 cm, with available distal diameters of 10, 12, and 14.5 mm. The main trunk is 5.5 cm long, containing a 2-cm-long gate that is 13 mm in diameter. The IIA component has a proximal diameter of 16 mm, a length of 7 cm, and available distal diameters of 10, 12, and 14.5 mm. As listed in the instructions for use (IFU), anatomical criteria exist to enable proper positioning and sealing of the IBE, including a CIA diameter ≥17 mm, an IIA diameter 6.5 to 13.5 mm, and a distance from the lowest renal artery to the CIA bifurcation ≥165 mm. In case of bilateral implantation of the IBE device, more distance from the lowest renal artery to the CIA bifurcation is required. Lengths ≥195 mm and ≥205 mm are required when using 23-mm and 27-mm bridging stent-grafts, respectively, but longer distances are needed if using the larger diameter (≥31 mm) main body Excluder aortic stent-grafts (https://www.goremedical.com/resource/MD141541).

Procedure

All the procedures were performed under general endo-tracheal anesthesia. When feasible, a bilateral percutaneous femoral approach was employed with the preclose technique using 2 ProGlide closure devices (Abbott Vascular, Santa Clara, CA, USA) deployed at the 1:30 and 10:30 o’clock position before the larger-diameter sheath was introduced, as previously described.⁵ The patient was systemically heparinized, and a 16-F DrySeal Flex sheath (Gore Medical) was advanced through the ipsilateral femoral approach while a 12-F DrySeal Flex sheath was advanced through the contralateral femoral approach. The IBE device was advanced through the ipsilateral 16-F sheath and after establishing through-and-through femoral access it was partially deployed, releasing the IIA portal. In the case of IIA aneurysms, embolization was attempted of any branch ≥2 mm taking off from the aneurysm sac. The bridging stent(s) was then advanced and deployed; if the intended distal landing zone was within the posterior IIA division, embolization of the anterior IIA division was performed. Kissing angioplasty of the 2 limbs of the IBE device was finally performed. In patients undergoing concomitant EVAR, standard bifurcated or fenestrated/branched stent-grafts (F/BEVAR) were implanted after completion of the IBD procedure. Several types of bridging stent-grafts were employed in addition to the IBE internal iliac limb: the Gore VBX (Gore Medical), the Gore Viabahn (Gore Medical), and the Atrium iCAST (Getinge, Hudson, NH, USA). All patients received dual antiplatelet therapy (clopidogrel 75 mg/d + aspirin 100 mg/d) for 1 month followed by lifelong single antiplatelet therapy. If the patient was on chronic anticoagulation for previous medical reason, dual antiplatelet therapy was avoided.

Clinical and Imaging Follow-up

The follow-up protocol called for clinical examination, laboratory tests, and imaging studies at 3, 6, and 12 months and annually thereafter. Imaging evaluation included computed tomography angiography (CTA) or CT without contrast enhancement and duplex ultrasound of the aortoiliac vessels. All imaging studies were independently evaluated by a group of vascular radiologists.

Study Outcomes

Early outcome measures were technical success, 30-day mortality, 30-day major adverse events (MAEs; composite endpoint of any cause mortality, acute myocardial infarction, stroke, spinal cord ischemia, acute kidney injury or new-onset dialysis, bowel ischemia, estimated blood loss ≥1 liter, and respiratory failure), and 30-day major access complications (any event necessitating a major surgical, medical, or endovascular intervention and including prolonged convalescence, rehospitalization, major amputation, permanent disability, or death). Technical success was defined as correct deployment of all endografts with complete exclusion of the aneurysm sac(s), patent target vessels, and absence of types I and III endoleak.

Late outcomes were survival, primary and secondary IIA patency, freedom from IIA branch instability, freedom from new-onset buttock claudication, and aneurysm sac diameter changes. IIA branch instability was defined as the composite cumulative endpoint of any IIA branch-related complications leading to aneurysm rupture, death, occlusion or stenosis/kink, disconnection, type I or III endoleak, or reintervention to maintain branch patency or to treat a separation or endoleak. Primary patency was defined as uninterrupted patency without procedures performed on or at the margin of the treated segment. Loss of primary patency was diagnosed when there was CTA or duplex ultrasound evidence of significant restenosis requiring treatment or thrombosis of the treated segment. Secondary patency was defined as restored patency through the original treated segment.

Statistical Analysis

Data were reported according to the Society for Vascular Surgery reporting standards for EVAR.³ Technical success, mortality, MAEs, major access complications, and survival were analyzed per patient. Patency and branch instability were analyzed per vessel. Patients with bilateral IBEs implanted in a division branch on either side were grouped with the division branch cohort for per-patient analysis. Results were reported as absolute numbers (with frequencies) for categorical variables and mean ± standard deviation for continuous variables. The Pearson chi-square or Fisher exact test was used for analysis of categorical variables. Differences between means were tested with the 2-sided Student t test, Wilcoxon rank sum test, or Mann-Whitney U test. Time-dependent outcomes were analyzed using life tables and displayed as Kaplan-Meier curves with differences determined using the log-rank test. Estimates are presented with the 95% confidence intervals (CI). Statistical significance was defined as p<0.05. Statistical analysis was carried out using JMP software (version 13; SAS Institute, Inc, Cary, NC, USA).

Results

Group Characteristics

There were no significant differences between the main trunk vs division branch groups in largest aortic diameter (mean 48±16 mm, p=0.12). However, patients receiving distal landing in the main trunk had smaller CIA diameters (mean 35±8 vs 41±13 mm, p=0.07), IIA diameters (mean 17±11 vs 23±15 mm, p=0.04), and aortic bifurcation diameters (mean 35±11 vs 39±9 mm, p=0.01) compared with those receiving distal landing in a division branch. A concomitant IIA aneurysm (≥10 mm diameter) was also less frequent in patients receiving distal landing in the main trunk (20% vs 89%, p<0.001).

Procedure Details

A bilateral percutaneous femoral approach was used in 80% of the cases (Table 2). In the entire cohort, 62 (84%) of 74 patients underwent concomitant aortic repair (9 F/BEVAR, 53 EVAR). In 14 (19%) patients the previously described “up and over technique”⁶ was required for IBE implantation due to the presence of prior aortic repair.

Table 2.

Procedure Details and Early Outcomes.^a

Variable	Overall (n=74)	Main Trunk (n=56)	Division Branch (n=18)	p
General anesthesia	74 (100)	56 (100)	18 (100)	>0.99
CBCT	51 (69)	41 (73)	10 (56)	0.24
Percutaneous femoral approach	66 (89)	50 (89)	16 (89)	>0.99
Unilateral	7 (9)	5 (9)	2 (11)	>0.99
Bilateral	59 (79)	45 (80)	14 (78)	>0.99
Treated side				0.46
Right	47 (56)	36 (59)	11 (48)
Left	37 (44)	25 (41)	12 (52)
Concomitant aortic repair	62 (84)	47 (84)	15 (83)	>0.99
F/BEVAR	9 (12)	7 (13)	2 (11)	>0.99
EVAR	53 (72)	40 (71)	13 (72)	>0.99
Concomitant IIA aneurysm	27 (36)	11 (20)	16 (89)	<0.001
Unilateral	18 (24)	10 (18)	8 (44)	0.03
Bilateral	9 (12)	1 (2)	8 (44)	<0.001
Upper extremity access	6 (8)	3 (5)	3 (17)	0.15
Left	2 (3)	1 (2)	1 (6)	0.42
Right	4 (5)	2 (4)	2 (11)	0.24
Contrast volume, mL	135±57	128±56	159±57	0.04
Procedure time, min	177±101	167±93	209±123	0.08
Fluoroscopy time, min	51±34	48±36	60±30	0.02
Cumulative air kerma, mGy	1137±963	960±786	1718±1255	0.02
Dose area product, Gy·cm²	189±133	168±112	264±177	0.16
Estimated blood loss, mL	239±340	219±322	214±178	0.47
Technical success	72 (97)	55 (98)	17 (94)	0.43
30-day mortality	2 (3)	1 (2)	1 (6)	0.43
30-day MAEs	7 (9)	4 (7)	3 (17)	0.35
30-day major access complications	7 (9)	5 (9)	2 (11)	>0.99
Follow-up, mo	17 (11–25)	18 (12–25)	16 (9–27)	0.74
Device design^b	(n=85)	(n=60)	(n=25)
IIA bridging stent				<0.001
IBE internal iliac limb	52 (62)	42 (69)	10 (43)
Viabahn stent-graft	9 (11)	1 (2)	8 (35)
iCAST stent-graft	4 (5)	4 (7)	0
VBX stent-graft	19 (23)	14 (23)	5 (22)
Additional stent	33 (39)	12 (20)	21 (91)	<0.001

Abbreviations: CBCT, cone beam computed tomography; EVAR, endovascular aneurysm repair; F/BEVAR, fenestrated/branched EVAR; IBE, iliac branch endoprosthesis; IIA, internal iliac artery; IQR, interquartile range; MAE, major adverse events.

Continuous data are presented as the mean ± standard deviation (or range) and categorical data are given as the number (percentage).

Data reported per vessel.

An individual technical failure in each group due to inability to catheterize the target vessel resulted in a 97% per-patient technical success rate (Table 2), without any difference between the groups (p=0.43). As expected, patients receiving distal landing in the main trunk required less contrast (128±56 vs 159±57 mL, p=0.04), as well as shorter procedure (167±93 vs 209±123 minutes, p=0.08) and fluoroscopy times (48±36 vs 60±30 minutes, p=0.02). The most used bridging stent-graft was the Gore IBE internal iliac limb (52, 62%) followed by the VBX stent-graft (19, 23%), the Viabahn stent-graft (9, 11%), and the iCAST stent-graft (4, 5%). As expected, a significantly lower proportion of patients with distal landing in the main trunk required placement of an additional stent (20% vs 91%, p<0.001). No significant differences were seen in right- vs left-sided procedures between the groups. Intraoperative complications (Table 3) were noted in 9 cases (13% vs 0%, p=0.18).

Table 3.

Details of Intraoperative Complications.

Patient	Group	Complication
1	Main trunk	Perforation of renal artery branch → coil embolization
2	Main trunk	Partial IIA occlusion → rescue parallel grafting between IIA and EIA
3	Main trunk	A portion of the IBE obstructed flow into the CIA → repeat kissing balloon dilation
4	Main trunk	Renal artery coverage → rescue stenting
5	Main trunk	Blood loss >1 liter from the sheath valve → intraoperative transfusion required
6	Main trunk	The Perclose device tore the artery, resulting in hemorrhage → primary repair of the femoral artery
7	Main trunk	Rupture of CIA during kissing angioplasty → rescue EVAR

Abbreviations: CIA, common iliac artery; EIA, external iliac artery; EVAR, endovascular aneurysm repair; IBE, iliac branch endoprosthesis; IIA, internal iliac artery.

Early Outcomes

Two patients died within 30 days, 1 in each group (p=0.43). Similarly, no significant differences were seen in the rates of 30-day MAEs (7% vs 17%, p=0.35) or 30-day major access complications (9% vs 11%, p>0.99) for patients receiving distal landing in the main trunk compared with the division branch. Regarding the individual MAEs, in addition to the 2 aforementioned deaths, all other events recorded were estimated blood loss ≥1 L (5% vs 11%, p=0.59).

Late Outcomes

The mean follow-up for the entire cohort was 19±12 months (19±12 vs 18±13 months, respectively; p=0.74) with an overall 1-year survival estimate of 94% (95% CI 74% to 99%), which was not significantly different between the groups (p=0.94, Figure 1A). The primary patency rate at 1 year was estimated at 98% (95% CI 88% to 99%) vs 95% (95% CI 72% to 99%, p=0.72) for patients receiving distal landing in the main trunk or in a division branch, respectively (Figure 1B). Similarly, high secondary patency was achieved with comparable 1-year rates in the groups [98% (95% CI 88% to 99%) vs 100%, p=0.41; Figure 1C]. No significant differences were found in the rate of branch instability between the groups (7% vs 13%, p=0.39; Table 4) or branch-related reinterventions (2% vs 13%, p=0.06). Freedom from branch instability was similar between the groups at 1 year: 93% (95% CI 82% to 97%) vs 90% (95% CI 66% to 97%, p=0.29; Figure 1D).

Table 4.

Branch Instability.^a

	Overall (n=85)	Main Trunk (n=60)	Division Branch (n=25)	p
Any branch instability	7 (8)	4 (7)	3 (13)	0.39
Branch-related reintervention	4 (5)	1 (2)	3 (13)	0.06
Branch occlusion	3 (4)	2 (3)	1 (4)	>0.99
Branch disconnection	1 (1)	0	1 (4)	0.27
Branch-related endoleak	5 (6)	3 (5)	2 (9)	0.61
Branch-related rupture	0	0	0
Branch-related death	0	0	0

Data reported per vessel as the number (percentage).

Freedom from new-onset buttock claudication estimates at 1 year were 98% (95% CI 86% to 99%) and 94% (95% CI 67% to 99%), respectively (p=0.62), with 2 events (one for each group) recorded during the first year of follow-up. The event in the patient selected for distal landing in a division branch was due to technical failure to catheterize the target vessel during the index procedure. The event in the patient with distal landing in the main trunk was due to thrombosis of the IBE side branch, which was not treated.

Mean aneurysm sac diameter change was 5.4±5.3 mm for the entire cohort, with similar means for the groups (5.7±4.9 vs 6.5±7.7 mm, p=0.85). Overall, 36 patients (43% of the entire cohort) were observed to have a ≥5-mm decrease of the aneurysm sac diameter (46% for the main trunk vs 35% for the division branch, respectively; p=0.46).

Discussion

According to the updated clinical practice guidelines from the Society for Vascular Surgery⁷ and the European Society for Vascular Surgery,⁸ preservation of blood flow to at least one IIA is strongly recommended during EVAR if it does not compromise aneurysm exclusion. IBDs represent the first dedicated endovascular option to preserve antegrade flow to the IIA, when anatomically feasible. Clinical studies and systematic reviews have shown excellent technical success, with extremely low morbidity and mortality rates in the perioperative period, as well as satisfactory device integrity and target vessel patency in the midterm.⁹ The major disadvantages of IBDs still are the anatomical requirements.^10,11 One common limitation is an inadequate distal landing zone because of coexisting IIA aneurysm or poor quality of the IIA main trunk, which may portend worse outcomes. Although outside of the device IFU, repair can still be done by extending the distal landing zone into healthy main division branches.^12,13 However, whether this would detrimentally affect the results of the procedure as compared with on-IFU distal deployment has not been extensively evaluated. Indeed, recent series have reported good technical and clinical results with implantation of IBDs for the treatment of IIA aneurysms despite a higher rate of endoleaks and reinterventions during midterm follow-up.^14,15 However, given the absence of a control group in these series, it might be questionable to extrapolate outcomes of IBDs for regular indications and to compare them with data from these studies.

The main findings of our study are that the Gore Excluder IBE can be deployed using the division branches of the IIA as distal landing zones without compromising the safety and 1-year effectiveness of treatment compared with standard cases where the distal landing zone was achieved within the IIA main trunk. Indeed, in the current series, the 94% technical success in challenging anatomy compared favorably with the 98% technical success reported in the group in which the IIA main trunk was used as the distal landing zone. Despite the expected increased technical complexity, contrast volume and total procedure or fluoroscopy times were statistically higher but were clinically comparable. There was no significant difference between the 2 groups in 30-day MAEs, with an overall rate of 9%, which compares well with the 8.8% rate recently reported for IBDs in a large national US database.¹⁶ Moreover, this technique remains effective at a median follow-up of 1.5 years as measured by aneurysm sac regression. Our results are largely similar to those recently reported by Jerkku et al,¹⁷ indicating that use of IBDs with distal landing beyond the IIA bifurcation may be a safe, feasible, and effective option for select patients with aortoiliac aneurysms, with outcomes comparable to those achieved using conventional landing into the main IIA trunk.

The overall branch instability rate reported in our series was higher for cases of distal landing in a division branch (13%) compared with cases of distal landing in the main trunk (7%), but this difference did not reach statistical significance. Although one cannot completely exclude the possibility of a type II error given the relatively small sample size, accurate analysis of the individual instability-related events revealed a trend toward significance only for the outcome of branch-related reinterventions, which were less frequent in patients with a main trunk distal landing. Although the indication for reintervention was not collected in the database, it might be that more reinterventions are needed to attain high secondary patency rates when landing a bridging stent-graft beyond the IIA bifurcation. However, loss of patency of the IIA side branch occurred in only 3 (4%) of 84 patients, which was almost identical between the 2 groups. Furthermore, all these events were observed early in follow-up, including 1 case of technical failure due to the inability to cannulate the posterior IIA branch intended as the distal landing zone for the device.

These findings are similar to contemporary series that have demonstrated how IBD occlusions occur mostly in the early postimplantation phase, suggesting that they were likely related to the technique or patient.¹⁸ Indeed, if the device is satisfactorily deployed and the IIA or its distal branches are well preserved, long-term stability can be expected.¹⁹ If any kink or compression is detected, prompt revision should be carried out to ensure optimal outcomes.²⁰ Our group uses postimplant cone beam CT intraoperatively to allow immediate assessment and revision of technical problems for IBDs and other complex endovascular aortic procedures.²¹

Two events of new-onset buttock claudication related to buttock ischemia were recorded in the current series, one for each group. One patient suffered perioperative buttock claudication as a result of technical failure to deploy the bridging stent-graft within the posterior division branch, while the other occurred as a result of symptomatic IIA side branch occlusion that was left untreated. One other branch occlusion in our series was completely asymptomatic for overall freedom from new-onset buttock claudication >95%. This compares favorably with the reported buttock claudication rate, which can be as high as 30%, after IIA sacrifice according to recent meta-analyses.^22,23 Therefore, it seems reasonable that the use of IBDs should be favored over IIA sacrifice in most patients, even in those with unsuitable or aneurysmal main trunks, provided that an adequate distal landing zone can be obtained beyond the IIA bifurcation.

A few technical points need to be addressed to ensure optimal and durable outcomes with these advanced procedures.

For preoperative planning and sizing, some anatomical features must be identified and addressed because they can predispose to IIA side branch occlusion. Although this has not been specifically investigated, extrapolation of data from the available literature on visceral/renal vessel stenting during complex F/BEVAR suggested that extreme angulation/tortuosity, small diameter, inadequate length, and/or severe calcification would prompt careful consideration.^24–26 Distal extension of the repair beyond the IIA bifurcation is normally done in our practice into the posterior division branch while using coils or plugs to exclude the anterior division branch. Our choice has been dictated by the fact that the posterior branch has a straighter course and usually provides the majority of pelvic blood supply. However, the aim is to use the best available division branch (which must have an internal diameter ≥6 mm and be free of circumferential calcification or sharp angulation) for distal landing downstream of the IIA bifurcation but using small side vessels is avoided. The safest maneuver in this case is to first place the proximal stent within the main trunk and then extend the repair distally to avoid losing guidewire access into the target branch (Figure 2). Alternatively, one can first deploy a long self-expanding covered stent starting distally in the gluteal branch and then add proximal stents as needed (Figure 3). The diameter of the deployed bridging stent-graft is chosen so to achieve a 10% to 20% oversizing as compared to the reference vessel.

In large IIA aneurysms with numerous side branches, it is important to exclude them all using coil embolization or vascular plugs since stent oversizing alone may not be sufficient to reliably prevent type II endoleaks. Although this might potentially increase the risk for postoperative buttock claudication, this has not been observed in our experience. The technique of going from one side branch to the other using a buddy catheter is very useful to minimize manipulation, particularly in the case of large intraluminal thrombus with potential concern for embolization. While data are scarce in the literature to assess the long-term clinical relevance of these type II endoleaks, one should consider that embolization of side branches when a stent-graft has already been deployed through an IIA aneurysm would be an extremely challenging (if not infeasible) procedure. Therefore, it has been our approach to perform embolization when it is relatively straightforward at the time of first intervention (Figure 4).

A wide range of balloon-expandable and self-expanding covered stents can be deployed within the IIA side branch, and the current literature is not adequately powered to address the question about the type of bridging stent-graft to be used.²⁷ A recent study from the pELVIS registry indicates that results of IBD for endovascular treatment of aortoiliac aneurysms are equally favorable with both balloon-expandable and self-expanding stent-grafts.²⁸ However, the authors did not specifically investigate whether the site of distal landing had any influence on outcomes.

When the repair is to be extended beyond the IIA bifurcation and more stents are necessary to bridge the longer distance to the distal landing zone, our preference is to use balloon-expandable stents (typically Gore Viabahn VBX 8L) or the IBE internal iliac limb proximally to provide stability, with self-expanding stents distally to ensure flexibility. Despite the intrinsic risk of more stent-related complications with the use of an additional or longer stent, the best strategy so far seems to be the use of more than one bridging stent-graft for a smooth transition between the devices and avoidance of diameter discrepancies.²⁹

Finally, the standard crossover technique may be more challenging in patients with narrow aortic bifurcations or previous bifurcated endografts but can be overcome using brachial access,^30,31 femoral access with steerable sheaths,^32,33 or an up-and-over technique.^5,34 However, one should carefully consider the increased technical complexity if a more distal target is to be reached with a non-standard approach so as to anticipate any potential intraoperative difficulty.

Limitations

Limitations of the study include its retrospective single-center design and small sample size, which may not allow generalization to other centers. Although reported in this study, buttock claudication in particular is a difficult endpoint to capture without a prospective design. In addition, the follow-up is relatively short, and longer follow-up is needed to determine the durability of the IBE device with regard to patency rates and efficacy. Also, the anterior branch was used as the distal landing zone in only 2 cases, preventing any meaningful comparison between its use and the posterior branch.

This study captures only patients who were deemed candidates for IBE implantation by experienced individual practitioners, which is a highly individualized and subjective process. Last, since this report gives technical and clinical outcomes after the use of a single manufacturer’s device, these data might not be directly extrapolated to other commercially available IBDs.

Conclusion

Use of the posterior or anterior division of the IIA as a distal landing zone for the Gore Excluder IBE was safe and efficacious over midterm follow-up. This technique may permit extending indications for endovascular repair of aortoiliac aneurysms to cases with unsuitable anatomy within the IIA main trunk. Long-term assessment is needed to affirm the efficacy of this technique.

Footnotes

Declaration of Conflicting Interests

The author(s) declared the following potential conflicts of interest with respect to the research, authorship, and/or publication of this article: Gustavo S. Oderich has received consulting fees and grants from Cook Medical, Gore Medical, and GE Healthcare (all paid to Mayo Clinic with no personal income).

Funding

The author(s) received no financial support for the research, authorship, and/or publication of this article.

ORCID iDs

Mario D’Oria

Emanuel R. Tenorio

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