ASDIN: Successful Endovascular Treatment of a Hemodialysis Graft Pseudoaneurysm by Covered Stent and Direct Percutaneous Thrombin Injection

Sonographer’s Role in the Screening, Diagnosis, and Treatment of Dialysis Fistula Pseudoaneurysms

Pseudoaneurysm (PSA) formation, in an arteriovenous fistula (AVF) undergoing hemodialysis, can occur as a result of frequent venipunctures and can lead to a weakened vessel wall. Since many dialysis patients’ lives depend on their weekly hemodialysis sessions, complications that result from dialysis require treatment. A PSA can be a life-threatening complication, especially for these patients. Sonography has been demonstrated to be a useful modality of choice in the screening, diagnosis, and treatment of a PSA. The sonographic appearance of a PSA using gray-scale, color, and spectral Doppler can play a significant role in ruling out other diagnoses. A case study is presented of a dialysis-dependent patient who developed a PSA in his dialysis access site. Sonography played a key role in the diagnosis and follow-up for this specific case. Due to the risks involved with these patients, there is an essential need for sonographers to be competent in performing these examinations. Evaluation of the AVF to check for patency and a thorough assessment of the PSA are required.

Aneurysms and pseudoaneurysms in dialysis access

Aneurysms are a common and often difficult complication seen with arteriovenous vascular access for haemodialysis. The purpose of this narrative review is to define and describe the scale of the problem and suggested therapeutic strategies. A narrative review of the published literature illustrated by individual cases is presented with the aim of summarising the relevant literature. The definitions of aneurysm are inconsistent throughout the literature and therefore systematic review is impossible. They vary from qualitative descriptions to quantitative definitions using absolute size, relative size and also size plus characteristics. The incidence and aetiology are also ill defined but separation into true aneurysms and false, or pseudoaneurysms may be helpful in planning treatment, which may be conservative, surgical or radiological. The lack of useful definitions and classification along with the multitude of management strategies proposed make firm evidence based conclusions difficult to draw. Further robust well designed studies are required to define best practice for this common problem.

Aneurysm Formation and Infection in AV Prosthesis

In contrast to autogenous arteriovenous (AV) fistulae where true aneurysms are the most frequent type, aneurysms in prosthetic AV grafts are mostly false aneurysms and less frequently anastomotic ones. Indications for repair comprise false aneurysms exceeding twofold the graft diameter, those with rapid enlargement or with skin thinning or erosion, the ruptured, those causing pain or severely limiting the cannulable area and the infected ones. They can be managed either with conventional surgery or with endovascular techniques; However, conventional surgery represents the current standard treatment consisting of either aneurysm resection and interposition graft in situ or resection/exclusion and bypass via a new route to avoid a potentially contaminated area.

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

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.

Role of stent grafts for the treatment of failing hemodialysis accesses

Covered stents or stent grafts are exciting new products with multiple applications for patients with vascular disease, including hemodialysis access-related complications. Although most of the current uses of stent grafts in these settings are "off-label" (ie, not approved by the US Food and Drug Administration) several studies are currently underway to provide the necessary data to support their application. It is clear that stent grafts provide a rapid, effective means for endovascular repair of ruptured access vessels. The commercially available devices and their current applications for treating access-related complications, including aneurysms/pseudoaneurysms, venous outflow stenoses, cephalic arch lesions, ruptures, and diffuse access stenoses, will be reviewed in this article. Available data are reported along with our current clinical practice and algorithms.

Review of central venous disease in hemodialysis patients

A common problem in the management of patients who are undergoing hemodialysis is central venous occlusive disease. There has been extensive literature on the treatment of this important and prevalent problem. Treatment options to date include percutaneous balloon angioplasty, bare metal stents, and surgical bypass. Unfortunately, all the available treatment options have poor long-term patency, requiring repeated interventions. More recently, covered stents have been mentioned in the literature for the treatment of central venous stenosis and obstruction. There are very few data to date on this technology, and further randomized controlled trials will be needed to compare the efficacy of percutaneous balloon angioplasty, bare metal stents, and covered stents. It appears that it is of paramount importance to prevent this difficult problem by limiting access to, or intervention in, the central venous system.

Endovascular stents for dialysis access: under what circumstances do the data support their use?

Despite strict K/DOQI clinical practice guidelines regarding the deployment of stents in the hemodialysis vascular circuit, their use has increased exponentially over the last 10 years in both arteriovenous fistulas and grafts. The literature is very scant regarding outcomes, with most studies suffering from design flaws. Some authors have advocated the use of stents for specific clinical scenarios, such as patients with thrombosed arteriovenous grafts or ones with a severe stenosis at the venous anastomosis. Others have advocated a more liberal strategy to deploy stents at a variety of sites if the stenotic lesion remains greater than 30% after angioplasty. Although not approved for the treatment of pseudoaneurysms in the AV grafts, stent use in this setting is emerging to be an important strategy. The use of stents as a treatment for rupture of a vessel while performing a percutaneous angioplasty is well described and performed routinely. It is important to recognize the clinical scenarios when stent placement may present a distinct disadvantage (eg, loss of a potential secondary fistula creation in the same extremity). Finally, well-designed studies need to address all these issues to clarify indications and to provide stronger scientific guidelines for stent use.