Endovascular treatment of stent fracture and pseudoaneurysm formation in arteriovenous fistula dialysis access

Abstract

Arteriovenous fistulae (AVF) and grafts (AVG) for hemodialysis access generally provide good long-term solutions for the patient with end-stage renal disease. However, complications of both AVGs and AVFs are common and require a multimodality approach to maintain their patency and continued use. Commonly encountered problems include stenosis, thrombosis, aneurysm or pseudoaneurysm formation, rupture, and infection. Each needs to be addressed on a case-by-case basis. Outflow stenosis, often occurring within the cephalic arch in patients with a brachiocephalic fistula, may occur alone or be discovered in conjunction with other access problems. Pseudoaneurysm of the venous end generally arises from traumatic weakening of the vessel wall, often from repetitive venipuncture. More rare is the fracture of a previously placed stent. We present a case of stent fracture complicated by pseudoaneurysm formation with concomitant stenosis of the cephalic arch treated successfully with single-procedure placement of endovascular stent grafts.

CASE DESCRIPTION

A 49-year-old man with end-stage renal disease (ESRD) with a left upper extremity brachiocephalic fistula presented with marked swelling of his left upper extremity. Ten months previously, he underwent placement of a stent graft (Fluency, Bard Peripheral, Tempe, AZ) for access site extravasation not amenable to conservative management. The left upper extremity was evaluated with sonography prior to the procedure and demonstrated a large pseudoaneurysm and associated hematoma (Figure 1). The patient could not extend his elbow, and the decision was made to access the left cephalic vein via a right groin approach from the right common femoral vein.

Figure 1.

Color Duplex interrogation of the fistula reveals the classic “ying-yang” color flow within a pseudoaneurysm.

After ultrasound-guided access using a standard Seldinger technique and placement of a vascular sheath, a 0.035-inch guidewire and 5F selective catheter were negotiated into the superior vena cava and into the left subclavian vein. Exchange was then made over an Amplatz guidewire (Boston Scientific, Natick, MA) for a 90 cm, 8F vascular sheath that was advanced into the left subclavian vein. Venography of the left cephalic vein was performed, confirming extravasation into a pseudoaneurysm (Figure 2). An 8 mm × 15 cm Viabahn (WL Gore, Flagstaff, AZ) stent graft was advanced, and the pseudoaneurysm and fractured stent were covered. Repeat venogram under a digital subtraction technique demonstrated stagnant blood flow due to poor venous outflow; therefore, the stent graft was extended to the level of the cephalic arch using an additional 8 mm × 5 cm Viabahn stent graft. The stent grafts were postdilated with an 8 mm × 40 mm Dorado balloon (Bard Peripheral, Tempe, AZ). Postangiographic imaging demonstrated successful occlusion of the bleeding pseudoaneurysm with no extravasation and robust venous outflow (Figure 3).

Figure 2.

Digital subtraction venogram obtained prior to intervention documents contrast extravasation into a cephalic venous pseudoaneurysm and stent fracture with separation (Type IV). Stenosis of the cephalic arch is also notable.

Figure 3.

Digital subtraction venogram following stenting reveals treatment of the stent fracture with exclusion of the pseudoaneurysm and normal flow through the cephalic vein.

DISCUSSION

Stent grafts have offered interventionalists an additional weapon in their arsenal for treating commonly encountered arteriovenous access complications from an endovascular approach and might offer improved long-term patency compared with treatment with percutaneous transluminal angioplasty (PTA) alone (1). The use of the stent graft to maintain circuit patency is considered off label. The only use of stent grafts approved by the Food and Drug Administration is for vessel rupture after PTA, although stent grafts have been used for a host of other problems routinely for many years (1–3). A study by Dolmatch et al highlighted the versatility of covered stent use in the treatment of dysfunctional access: they treated a myriad of problems with the Fluency stent graft with a high rate of technical success and a low rate of complications (3). Cephalic arch stenosis is a commonly encountered problem with brachiocephalic fistulae, reported to develop in up to 77% of cases. A retrospective study by Shawyer et al demonstrated the effective treatment of cephalic outflow stenoses with the Viabahn-covered stent graft, showing improved rates of access patency compared with the previously reported data for bare metal stents (4). Failure to address problems in the venous outflow as in our case can lead to early failure of corrective procedures performed for arteriovenous access problems elsewhere.

Rare but increasingly reported are stent fractures, a known complication of stent placement elsewhere in the body. Cases of fractured stents placed for the treatment of coronary artery disease (5), peripheral vascular diseases (6), and chronic mesenteric ischemia (7) have been reported. Factors thought to contribute to stent fracture include placement in motion-prone segments, compressive forces, stretching of the stent during placement, and the presence of overlapping stents (5–7). Stent fractures have been classified in one system as type I to IV, with type I reflecting a single strut fracture; type II, multiple strut fractures; type III, multiple strut fractures resulting in complete transverse fracture; and type IV, a complete transverse fracture with stent separation (7). In our reported case, a type IV fracture was clearly evident on fluoroscopy, given the above parameters.

Pseudoaneurysms commonly arise at sites of cannulation through weakening of the vessel wall, although the development of pseudoaneurysms appears multifactorial, with high pressures from arterial flow and venous outflow stenosis being implicated. The presence of pseudoaneurysm is problematic and can lead to an increased risk of rupture with potential exsanguination, compromised viability of the overlying skin, limitations in the territory available for cannulation, infection, and cosmetic concerns. Indeed, the National Kidney Foundation guidelines recommend treatment when a pseudoaneurysm limits cannulation availability or when viability of the overlying skin becomes compromised (8). Historically, surgical revision was required, although now there are numerous case reports of successful exclusion of the pseudoaneurysm via the placement of stent grafts (9) with or without thrombin injection (10). Following placement of a stent graft, issues relative to cannulation territory may remain, and indeed it has been suggested that access through a stent graft should be avoided given potential complications and the lack of long-term safety data (11). These issues remain unresolved at present, and theoretical drawbacks of endovascular treatment must be carefully considered when either surgical revision or access abandonment appear to be the only options. The access in this case was salvaged by endovascular management and remained patent and usable at 10-month follow-up, despite necessary cannulation through the stent grafts.