Deployment Failure of a Stent-Graft During Arteriovenous Access Procedure

Introduction

Endovascular stents have been widely utilized in the management of arteriovenous access (AVA) dysfunction. ¹ Device-related complications and adverse events can occur during its deployment such as deployment failure, migration, and device failure. ² These inadvertent events can impose a dire consequence on the patients. Although the deployment failures are extremely rare and were described only once in the literature, ³ it is worth to report another case of failed deployment of the particular stent to alert the interventional colleagues about this astonishing complication.

This study was carried out in accordance with the Declaration of Helsinki and case reports of less than 3 do not require institutional review board approval at my institution.

Materials and Methods

A 57-year-old man on hemodialysis for the past 7 years presented with local swelling of his arm. The patient had a transposed brachiobasilic AVA, which functioned until approximately a year ago. The access developed multiple strictures, aneurysmal dilatations, and infections that could not be repaired. A bovine mesenteric vein graft (6 mm diameter × 30 cm length, ProCol Vascular Bioprosthesis; LeMaitre Vascular, Inc, Burlington, Massachusetts) was subsequently placed to reconstruct the access. Subsequently, the venous outflow stenoses of the access were revised by balloon dilatation angioplasties. On the last admission, the access was found to have multiple pseudoaneurysms along the needle puncture sites. To seal off these pseudoaneurysms, attempts were made to deploy a covered stent-graft. A 10 mm × 10 cm stent-graft (Gore Viabahn Endoprosthesis with Heparin Bioactive Surface; W. L. Gore & Associates Inc, Flagstaff, Arizona) was inserted via an 11F vascular introducer sheath and placed in the target access area. The stent deployment was initiated by pulling the deployment line, but at the halfway point, the line could not be pulled any more, leaving the rest of the stent still constrained (Figure 1). After multiple attempts failed to remove the incompletely deployed stent by pulling back into the sheath, the stent and its delivery catheter were retrieved by opening the access through a skin incision. The access was repaired by the replacement of the pseudoaneurysmal segment with a new ProCol graft. In the back table, attempts were made further to deploy the retrieved stent-graft without success (Figure 2). The manufacturer, W. L. Gore & Associates Inc has examined the explanted stent to find no structural defect in the stent.

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Figure 1.

Incompletely deployed stent-graft in an arteriovenous fistula in the left upper arm.

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Figure 2.

The retrieved stent-graft from the arteriovenous fistula and further attempts were made to deploy the stent further in the back table.

Discussions

Although the use of endovascular stent-grafts for the management of vascular access dysfunction increases, inadvertent mechanical complications during deployment are rarely encountered. The case described herein is an unexpected deployment failure of a Viabahn stent, which is usually deployed by pulling the deployment line away from the deployment catheter. The deployment line consists of an expanded polytetrafluoroethylene (ePTFE) constraint filament, which in this case, was peeled away to the midpoint of the stent but could not be pulled farther. On examination of the retrieved device from the access, the stent showed entanglement of this filament with the Nitinol stent wire in the midportion of the stent. The event conceivably leading to this entanglement was the separation of the external Nitinol structure from the underlying ePTFE graft, making the constraint filament vulnerable to entanglement. The likely cause of such a separation is the improper manipulation of the stent during the deployment process, such as acute kinking or bending of the stent, passing of the stent back and forth through the tight introducer sheath, or repositioning of the partially deployed segment of the stent in the middle of the deployment process. The filament entanglement in the case reported herein is believed from the unrealized attempts of stent repositioning. Ferguson and Cwikiel reported that placement of a larger diameter Viabahn through a preexisting stent may carry a risk of failed deployment. ³ It is quite possible that their stents failed to deploy fully because the filaments were entangled at the struts of the preexisting bare-metal stents.

When the deployment of a stent has started in the target vessel area but fails to be completed, the partially deployed stent cannot be removed by pulling back into the introducer sheath in place because the Nitinol struts do spread over the leading edge of the sheath and block further advancement. However, Ferguson and Cwikiel have successfully removed the partially deployed stent-grafts (11 and 13 mm diameter, respectively) by percutaneous endovascular technique through a 16F sheath. They have used a lot of force to move these inside the sheaths, and once the stents were inside the sheath, the sheaths were removed from the patients. In my personal ex vivo experiment, it was confirmed the partially expanded stent can be ensheathed and reconstrained into an extra-large size sheath when forceful pull was exerted to flip over the external support of Nitinol struts. Alternatively, the entire delivery system catheter with the partially deployed but still attached stent-graft can be simply pulled out in tandem with the introducer sheath by making a small incision on the fistula around the sheath. The incision can make just large enough opening to allow the expanded stent to be pulled out and can be suture repaired.

While the exact cause of this deployment failure warrants further investigation, the stent-graft should be carefully examined to confirm its integrity and follow the recommendation of the manufacturer. ² During the deployment process, any improper manipulations should be avoided while holding the access flow to a standstill for the safe deployment without inadvertent migration of the stent. ⁴