Re-intervention for type III endoleak after endovascular aneurysm repair with an ALTO stent graft: a case description

Introduction

Approximately 30% of patients who undergo endovascular aneurysm repair (EVAR) for abdominal aortic aneurysms (AAAs) develop endoleaks (1). Among patients with an endoleak, 12–20% require re-intervention (2,3). Type III endoleaks are usually caused by a defect within the graft material or by structural failure, causing separation between the components or inadequate overlap. Type IIIa endoleak is classified as a disconnection of components, while type IIIb endoleak is classified as a fabric tear or stent fracture of the graft material. Such cases are classified as high-pressure/high-risk leaks because they allow direct communication between the arterial system and the aneurysm sac, which may occur during graft deployment or during follow-up (4). Once detected, immediate treatment is imperative because the aneurysm sac is exposed to systemic pressure (5). Furthermore, it was reported that only 20% of type IIIb endoleaks are detectable with computed tomography angiography (CTA) (6), suggesting that the reported incidence of 2–4% may be underestimated (7-9).

The ALTO stent graft (Endologix LLC, Irvine, CA, USA) for AAAs became available in Japan in 2021. In contrast to conventional stent grafts, the ALTO stent graft has a proximal ring structure into which an artificial resin polymer is injected, allowing close contact between the proximal neck (PN) and the vessel wall. This stent graft is also suitable for cases with a short PN of 7 mm, while its proximal stent extends to the celiac artery (10-12). We recently encountered a patient with a suspected type IIIb endoleak after EVAR with an ALTO stent graft and performed redo-EVAR. Because this is a rare situation with few previously published cases, we believe that this case is worth reporting.

Case presentation

The case was an 81-year-old man with no particular complaints. His medical history consisted of hypertension, myocardial infarction, and benign prostatic hyperplasia. He had a history of aspirin use. He previously underwent EVAR using an ALTO stent graft (Endologix LLC) for an AAA with a maximum diameter of 57 mm (Figure 1A,1B). For EVAR, the PN length was 58 mm and the PN diameter was 24‒25 mm. Therefore, a 29 mm main device (TV-AB2980-N), right leg (TV-IL1418120-J), and left leg (TV-IL1412160-J) were selected. An aneurysm was found in the left common iliac artery, and his left internal iliac artery was embolized using coils, followed by a left external iliac artery landing. To prevent type II endoleak, the inferior mesenteric artery was intraoperatively embolized using a 6 mm AVP4 (Abbott, Plymouth, MN, USA). Polymer filling and contralateral cannulation were uneventful. Final angiography did not reveal any type I or type III endoleaks (Figure 1C). Contrast-enhanced computed tomography (CECT) performed 1 week after EVAR also showed no obvious endoleak. Six months after EVAR, a type II endoleak was suspected, but the patient was placed under observation because the aneurysm diameter did not increase. CECT performed 1 year after EVAR revealed enlargement of the aneurysm and a persistent type II endoleak (Figure 2A,2B). An endoleak was also suspected on the dorsal side of the main body (Figure 2B,2C). Because further examination of this endoleak was deemed necessary, the patient was hospitalized for examination and treatment.

Figure 1 Preoperative CECT. (A) Image showing an AAA with a preoperative maximum short diameter of 57 mm. (B) Virtual reality image showing a long neck AAA within the instructions for use. (C) Final angiography showing no evidence of an endoleak after EVAR with an ALTO stent graft. AAA, abdominal aortic aneurysm; CECT, contrast-enhanced computed tomography; EVAR, endovascular aneurysm repair.

Figure 2 Postoperative CECT performed 1 year after EVAR. (A) Image showing a type II endoleak (white arrow). (B) Sagittal CECT image showing a type II endoleak (white arrow) and the presence of an endoleak, not type II, on the dorsal side of the main body (white arrowhead). (C) Image suggesting the presence of an endoleak, although not a type II endoleak, on the dorsal side of the main body (white arrow). (D) Sagittal time-resolved CTA image showing a type IIIb endoleak from the dorsal part of the main body just above the flow divider (white arrow). CECT, contrast-enhanced computed tomography; CTA, computed tomography angiography; EVAR, endovascular aneurysm repair.

A 4 Fr sheath (Terumo, Tokyo, Japan) was inserted through the femoral artery. A 4 Fr pigtail catheter (Medikit, Tokyo, Japan) was inserted to the level of the origin of renal artery. Angiography revealed no obvious type I endoleak. Next, time-resolved CTA (Aquilion ONE, Canon Medical Systems, Otawara, Japan) was performed from within the graft near the graft bifurcation and revealed a type IIIb endoleak within the aneurysm from the dorsal part of the main body just above the flow divider (Figure 2D).

We decided to redo-EVAR. The plan was to place the type IIIb endoleak in the main trunk using the double D technique with cuff lining and bilateral inverted legs, which procedure involves inserting two limbs of the same diameter in parallel into the proximal cuff stent-graft within the abdominal aorta, which has been previously placed, (13). Because the type IIIb endoleak was directly above the flow divider, the cuff was placed directly above the flow divider, and the inverted leg was placed to avoid interfering with the renal artery. The ALTO main body was placed at a position where the abdominal aorta diameter was 29 mm. Because the inner diameter of the trunk was 23 mm, we planned to apply a 23 mm excluder cuff (W. L. Gore & Associates, Flagstaff, AZ, USA) and 20 mm inverted contralateral legs (W. L. Gore & Associates) on both sides (Figure 3A,3B). Endovascular treatment was performed with no particular problems (Figure 4A,4B) and a CECT scan immediately after redo-EVAR showed that the type IIIb endoleak had disappeared. Several days after the procedure, transcatheter arterial embolization (TAE) was performed using approximately 0.8 mL of n-butyl-2-cyanoacrylate (NBCA; Histoacryl, B. Braun, Melsungen, Germany)-lipiodol (Guerbet, Villepinte, France) to treat the type II endoleaks in the bilateral L4 lumbar arteries (Figure 5A,5B).

Figure 3 Final angiography after the redo-EVAR. (A) Arterial phase angiograph showing no evidence of an endoleak after the redo-EVAR. (B) Delayed-phase angiograph showing no evidence of an endoleak after the redo-EVAR. EVAR, endovascular aneurysm repair.

Figure 4 CECT performed 1 week after the redo-EVAR. (A) Image showing the double D shape, as planned, before the redo-EVAR. (B) Virtual reality image showing the stent graft configuration, as planned preoperatively. CECT, contrast-enhanced computed tomography; EVAR, endovascular aneurysm repair.

Figure 5 Images showing the presence of a type II endoleak and treatment by TAE. (A) Angiograph showing the type II endoleak (white arrowhead) before TAE. The right L4 lumbar artery (white arrow) served as the inflow artery and the left L4 lumbar artery (black arrow) as the outflow artery. (B) Angiograph obtained after TAE showing no evidence of an endoleak. TAE, transcatheter arterial embolization.

Currently, the patient is being followed up for 6 months after redo-EVAR, and the endoleak has disappeared and no expansion of the aneurysm has been observed on CECT.

All procedures in this study were performed in accordance with the ethical standards of the institutional and/or national research committee(s) and with the Declaration of Helsinki and its subsequent amendments. Written informed consent was obtained from the patient for publication of this article and accompanying images. A copy of the written consent is available for review by the editorial office of this journal.

Discussion

Lyden et al. reported that the Alto abdominal stent graft is safe and effective in treating AAAs with appropriate anatomy at 1 year. According to their report, through 1-year post-treatment, all-cause mortality was 4.0%. No AAA-related mortality occurred. AAA enlargement was 1.6%, type I endoleak rate was 1.4%, with 100% freedom from type III endoleaks, device migration, device fracture, stent occlusion, or AAA rupture. The device-related secondary intervention rate was 2.7% (10). On the other hand, in our case, 1 year after EVAR, we suspected aneurysm enlargement due to type III and type II endoleaks, necessitating secondary intervention. This is considered an extremely rare case, as there have been few reported cases in the past.

Type IIIb endoleaks have been reported to be common in trunks and flow dividers (14). In this case, a type IIIb endoleak was found in the main body directly above the flow divider, which is consistent with previously reported locations (14). The possible causes of the type IIIb endoleak in this case are diverse, including damage during manufacturing, damage during deployment from the delivery system or during leg device placement after main body placement, and damage to the graft during balloon touch-up (6). Because the leg device was placed slightly beyond the flow divider, the latter cannot be ruled out, but the exact cause remains unknown. There has been one reported case of type III endoleak detected 4 years after EVAR using an ALTO stent graft in which iliac stent relining was performed (11). However, the authors did not mention whether the endoleak was due to component separation or fabric tears (11). Therefore, the present case is extremely rare.

Previous reports suggest that endovascular treatment using stent graft relining is more common for treating type IIIb endoleak than surgical treatment (14). Regarding the selected sizes of the aortic cuff and leg, the length of the semicircular portion of the leg, which is deformed into a D-shape by parallel insertion, corresponds to half the circumference of the aortic cuff, and the length of the straight portion corresponds to the diameter of the aortic cuff. Therefore, the circumference of the leg to be inserted parallel must be at least half the circumference of the aortic cuff plus the diameter of the aortic cuff, which is approximately 82% of the diameter of the aortic cuff (13). Therefore, we inserted an Excluder contralateral leg (16‒20 mm) upside down into an Excluder aortic cuff (23 mm) using the same sizing.

A type IIIB endoleak was diagnosed in our case following time-resolved CTA. In a prior report, Type III endoleak due to defective polymer sealing of the ovation was identified (15). Our patient was initially misdiagnosed as having a type II endoleak based on CECT, and digital subtraction angiography was unclear. Time-resolved CTA was useful in reaching the diagnosis of type IIIb endoleak. Time-resolved CT angiography is an imaging diagnostic method that can visualize hemodynamic changes over time. We believe it can enable the diagnosis of type IIIb endoleaks, which are difficult to diagnose with conventional methods, potentially leading to a reduction in the risk of complications and improved long-term prognosis. Contrast-enhanced ultrasound should also be considered in endoleak detection without carrying the risks of radiation exposure or nephrotoxicity (16), although it was not used in this case.

Our report has a limitation. Although we diagnosed a type IIIb endoleak using time-resolved CTA, the diagnosis was not made by inserting a catheter into the graft fracture. This means that the suspicion remains that this was not a type IIIb endoleak, but a type IIIa endoleak due to poor graft adhesion or a combination of type IIIa and type IIIb endoleaks. However, time-resolved CTA clearly identified a pinhole-like endoleak leaking from within the graft into the aneurysm, allowing us to diagnose it as a type IIIb endoleak.

In conclusion, we experienced a suspected case of type IIIb endoleak after EVAR using an ALTO stent graft. Time-resolved CTA was valuable for reaching the diagnosis of type III endoleak. Re-intervention EVAR using the double D technique with an excluder aortic cuff and inversion of the excluder leg successfully treated the type III endoleak that occurred after the EVAR with an ALTO stent graft.

Acknowledgments

None.

Footnote

Funding: None.

Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at https://qims.amegroups.com/article/view/10.21037/qims-2026-0733/coif). The authors have no conflicts of interest to declare.

Ethical Statement: The authors are accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved. All procedures in this study were performed in accordance with the ethical standards of the institutional and/or national research committee(s) and with the Declaration of Helsinki and its subsequent amendments. Written informed consent was obtained from the patient for publication of this article and accompanying images. A copy of the written consent is available for review by the editorial office of this journal.

Open Access Statement: This is an Open Access article distributed in accordance with the Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International License (CC BY-NC-ND 4.0), which permits the non-commercial replication and distribution of the article with the strict proviso that no changes or edits are made and the original work is properly cited (including links to both the formal publication through the relevant DOI and the license). See: https://creativecommons.org/licenses/by-nc-nd/4.0/.

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