Modified upside-down technique with Gore tapered iliac limbs for isolated iliac artery aneurysms

Introduction

Isolated iliac artery aneurysms are an uncommon condition affecting approximately 2% of patients with aneurysmal disease. ¹ Iliac artery aneurysms extending from the Common Iliac Artery (CIA) to the External Iliac Artery (EIA) can be treated by open surgery or endovascular treatment. Open surgical repair is technically challenging and associated with high rates of morbidity and mortality. ²

Endovascular treatment is based on branched endoprosthesis to preserve Internal Iliac Artery (IIA) or in case of unsuitability, IIA embolization and aneurysm exclusion with covered stents.

Proximal and distal landing zone diameter discrepancies with proximal CIA landing zone significantly larger than distal EIA landing zone, can severely limit the endovascular available options in absence of specific tapered devices.

Previous case reports and technical notes have described the inversion of Endurant (Medtronic Cardiovascular, Santa Rosa, California), Zenith (Cook, Inc., Bloomington, Indiana), and Gore (W. L. Gore & Associates Inc, Flagstaff, Arizona) iliac limbs to overcome this issue.^3–7

We report an original technique of extracorporeal inversion of a Gore Excluder contralateral tapered leg and subsequent controlled release. The case of a 76 year-old male with CIA/EIA aneurysm and IIA chronic occlusion is reported.

Technique

The procedure starts by cutting with Mayo scissors 2 cm of the tip of an 18 Fr 33 cm sheath introducer Gore DrySeal (Figures 1.1 and 2.2). A 15 Fr Gore DrySeal introducer sheath is then prepared with cutting of sheath’s dilator (Figures 1.2 and 2.1). The cut should be approximately 1 cm long; a longer cut could worsen blood leak through dilator’s central lumen. After the cutting maneuvers, the surgeon must ensure a blunt end of the introducers to avoid arterial damage (Figure 1.1 and 1.2).OPEN IN VIEWER

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Figure 2.

2.1: 15 Fr sheath introducer and cutting of the 15 Fr dilator; 2.2: cutting of the 18 Fr sheath introducer; 2.3: co-axial 15-18 Fr sheath introducers system; 2.4: tip-to-tip endograft delivery inside the 15 Fr introducer sheath; 2.5: complete system, from the top to the bottom: 15 Fr sheath introducer with endograft internally deployed and 4 Fr catheter inside; 15 Fr dilator previously cut; 18 Fr introducer sheath cut with inserted 18 Fr dilator.

The 18 Fr introducer is flushed, and differently the 15 Fr introducer is maintained dry to avoid graft migration during the release inside the introducer. The tapered endoprosthesis is therefore prepared by bending and cutting with Mayo scissors the olive at the tip of the graft releasing system (Figure 1.3) and inserted in a tip-to-tip fashion into the 15 Fr introducer sheath (Figures 1.4 and 2.4) The graft is then deployed in the introducer by pulling the releasing wire (Figure 1.5). The back tip of a 0.035″ guidewire (Radifocus™ Guide Wire M Standard Type, Terumo Aortic Ltd, Renfrewshire, Scotland, United Kingdom) is inserted into the graft releasing system. A 4 Fr 100 cm Bern catheter (Tempo, Cordis Corporation, Bridgewater, New Jersey) is inserted into the tip of the aforementioned guidewire (Figure 1.6). The graft releasing system and the guidewire are then pulled away.

The system is now ready for deployment (Figures 1.7 and 2.5).

After heparinization, the previously cut 18 Fr introducer sheath is inserted into the femoral artery and advanced up to the proximal sealing zone. Following the removal of the 18 Fr dilator, the 15 Fr introducer is inserted in a co-axial fashion into the 18 Fr introducer (Figure 1.7). Using the previously mounted catheter, an extra stiff 0.035″ guidewire is positioned. After removing the catheter, the pre-cut 15 Fr dilator is brought up to the endograft and used as a pusher. A pull-back maneuver of the co-axial system, maintaining the dilator in position, allows the controlled and correct delivery of the endograft (Figure 1.8).

The technique was applied in a 76 year-old male with incidental finding at a CT scan of a 40 mm diameter aneurysm involving both CIA and EIA coupled with chronic occlusion of the IIA. The proximal CIA diameter was 23 mm and distal EIA diameter was 15 mm. No relevant findings nor symptoms in his past medical history were recorded. Written informed consent was obtained from the patient for publication of this case report and any accompanying images.

Three-dimensional reconstructions and vessel measurements were acquired by multi-planar reconstruction with OsiriX software (Pixmeo, Geneva, Switzerland). Fluoroscopy acquisitions were obtained with C-Arm Ziehm Vision FD Vario 3D (Ziehm Imaging GmbH, Nürnberg, Germany). Under general anesthesia, bilateral femoral percutaneous access and systemic heparinization with 5000 IU were performed. Percutaneous vascular closure devices ProGlide (Abbott Vascular, California, USA) were positioned in preclose technique. ⁸ The abovementioned system was positioned via left femoral access. A pigtail catheter was positioned through right access. The initial angiogram confirmed the CT-finding of a CIA/EIA aneurysm with chronic occlusion of the IIA (Figure 3.1).OPEN IN VIEWER

The endograft selected was a Gore Excluder contralateral tapered leg with 27 mm proximal diameter, 16 mm distal diameter, and 140 mm length. After deployment of the graft, a final angiogram was performed showing the complete exclusion of the aneurysm without signs of endoleak or migration (Figure 3.4).

Patient was discharged with single anti-platelet therapy after 2 days of hospitalization. A CT-based follow-up was planned.

At 30 days, CT-scan confirmed the previous findings with good positioning of the graft and exclusion of the aneurysm (Figure 4.4).OPEN IN VIEWER

Discussion

Iliac isolated aneurysm can be repaired by surgical or endovascular approach. In a recent systematic review, mortality was significantly lower in endovascular interventions than in surgery (8.2% vs 2.8%) underlining the role of endovascular therapy as the first-line treatment. ⁹

Endovascular approaches vary between IIA coverage and embolization to aneurysm exclusion with IIA preservation. Simple aneurysm exclusion coupled with IIA embolization represents an option with low rates of postoperative complications and high primary patency.^10,11 In emergency settings in which hypogastric flow could not be maintained, IIA embolization should be performed prior to graft deployment with the described technique. In other cases, IIA can be selectively preserved with branched grafts with high rates of technical success (98%) and moderate endoleak occurrence (11.9%). ¹²

In our case, branched devices were unfeasible due to chronic IIA occlusion while no available standard grafts could adapt to the anatomy of the patient.

EndoVascular Aneurysm Repair (EVAR) can be performed but with unnecessary coverage of a healthy infrarenal aorta. ¹³

Iliac limb grafts normally used in EVAR are the only available grafts with significant imbalance between proximal and distal diameters. Zenith Alpha Spiral-Z endovascular leg (Cook Inc, Bloomington, Indiana, USA) has 12 mm as proximal diameter and distal diameters up to 24 mm. Gore Excluder AAA endoprosthesis iliac leg (W. L. Gore & Associates Inc, Flagstaff, Arizona, USA) has a proximal diameter of 16 mm and distal diameter up to 27 mm. Endurant II (Medtronic, Minneapolis, Minnesota, USA) grafts have iliac limbs with a 16 mm proximal diameter and distal diameter up to 28 mm. All the abovementioned iliac limbs have smaller diameter upwards and bigger diameter downwards and therefore, according to the IFUs can’t be employed in cases of proximal landing zone significantly larger than distal landing zone.

A cross-over deployment technique to invert such limbs was described but could be limited by severe angulations of the aortic bifurcations. ¹⁴

To adapt in different anatomies, case reports and technical notes have been published about the possibility of extra-corporeal deployment and inversion of iliac limb grafts.^3–7

All of the previously described techniques require unloading, reorienting, and reloading of the prosthesis. The prolonged graft manipulation needed to reposition the graft could damage silk sutures or fracture the metallic scaffold resulting in type III endoleak or intraprocedural deployment complications. ¹⁵ Furthermore, extensive handling of the endoprosthesis raises infective risk. ¹⁶

In contrast our technique consists in an extra-corporeal deployment of the graft inside an introducer sheath, which limits significantly manipulation and the possible graft damages deriving from it.

Moreover, one of the principle advantages is avoiding direct graft handling.

Differently from other techniques where the graft is constrained by an expanded polytetrafluoroethylene fluorinated ethylene propylene sleeve, in our case the sleeve comes off during the intra-sheath release. Accuracy of the deployment is given by countertraction between the 18 Fr introducer sheath pull-back maneuver and the 15 Fr cut dilator used as a pusher. Risk of twisting during delivery seems to be low.

Deployment of the iliac leg Excluder stent graft with this upside-down modified technique is reliable and enables correct deployment; however, its application is limited to a few cases in which other endovascular approaches are not available.

Conclusions

Despite being an off-label use of the graft, the modified upside-down technique offers a feasible option in case of endovascular exclusion of isolated iliac artery aneurysms in presence of proximal landing zone significantly larger than distal landing zone. Extracorporeal deployment inside the introducer sheath is time-saving and could be safer in terms of graft damage and infection. Caution must be applied considering the use of this technique out of the IFUs.