Percutaneous Arterial Venous Fistula Creation

Hemodialysis is a tremendous socioeconomic burden within industrialized countries, with costs exceeding 1.5 billion dollars in Europe and within 2.9 billion dollars in annual costs in the United States. A large and essential component for delivery of dialysis is a stable and usable hemodialysis access. There are primarily three kinds of access: the catheter, a dialysis graft, and a dialysis fistula. The latter, a direct surgical connection between the artery and the vein, is considered an ideal access because it is associated with lower costs and improved durability. Since the introduction of the Quinton-Scribner shunt in 1960 and the Brescia-Cimino autogenous fistula in 1966, there has been little technical or surgical innovation to improve on the original fistula surgery.

Although an arteriovenous fistula (AVF) is the recommended access because of its associated low mortality, morbidity, and cost compared with other access types, after AVF creation, between 20% and 60% do not successfully mature or are rendered unsuitable for hemodialysis, subjecting patients to prolonged catheter dependence and its associated morbidity and mortality. Also, AVFs require an average of 1.5 to 3.3 interventions to facilitate usability for hemodialysis. Ultimately, the combination of these factors increases patient reluctance to undergo surgical fistula creation, particularly those with previously failed fistulas.

In attempts to address the issues of surgical fistulas new autogenous fistulas, prosthetic dialysis accesses, different materials and modifications of current concepts have been adopted. These advances have led to improved hemodialysis initiation times, quality of dialysis, maintenance of accesses, and outcomes in patients. Despite these advances the requirement for initial surgical placement remains unchanged. Variability in outcomes has been attributed to variations in surgical technique, quality of vessels, and multiple other factors. To overcome this variability various devices and drugs have been studied with limited to no success. These include the Optiflow device, which standardizes the arteriovenous anastomosis, human pancreatic elastase, and bioengineered blood vessels ( clinicaltrials.gov ; NCT01744418).

The constants with surgical creation include an incision, dissection, vessel transection, and stitching. These steps are associated with hypoxic injury of the vein, which is the trigger for intimal hyperplasia followed by venous stenosis, the primary cause of fistula failure. Percutaneous creation of a fistula would potentially avoid this ischemic injury. Other potential advantages include greater technical success, consistent anastomotic creation, and multiple endovascular specialists capable of performing the procedure. All these factors put together would hopefully lead to improved adoption, usage, lower dysfunction, and potentially reduced costs to healthcare systems.

History

Any percutaneous creation would involve the creation of an artery-to-vein anastomosis, or an artery/graft–to–graft/vein anastomosis. Keeping this in mind, there have been isolated reports of percutaneous fistulas being created but most of these are modifications of prior working fistulas or grafts surgically created that have failed. In an animal study, Trerotola et al. in 1995 created an entirely percutaneous hemodialysis graft within the dog model which met with later failure but no subsequent known further investigation, modification, translation to human use, or larger study. Beyond these reports, there are prior failed methods and attempts or devices that have not reached implementation in humans. Initial reports described the surgical creation of an arterial anastomosis with percutaneous creation of the venous anastomosis with stent grafts in humans. This does not fit the definition of an autogenous hemodialysis fistula.

Percutaneous Creation

Since 2015, two devices have shown technical success in creation of a dialysis fistula percutaneously with functional patency. The first is the original FLEX device, now called the everlinQ device by TVA Medical (Austin, TX); this was the first device described for use in humans. The second is the Ellipsys device by Avenu Medical (San Juan Capistrano, CA).

EverlinQ Devices

The TVA devices use radiofrequency energy to percutaneously create a sutureless arteriovenous anastomosis in humans with success. TVA’s everlinQ endovascular AVF system consists of two 6F (everlinQ or everlinQ square) or 4F catheters (everlinQ 4) that contain rare earth magnets ( Fig. 82.1 ). The magnets are imbedded within the catheters and cause alignment of the catheters within the artery and vein, and the magnetic attraction pulls the vessels together. The catheters themselves are hydrophilic. Within the venous catheter a footplate is released/present and radiofrequent energy is delivered for less than 2 seconds, vaporizing the tissue and vessel walls between the artery and the vein creating, a 1 mm × 5 mm fistula. Blood then flows from the artery into the veins of the deep venous system and via perforators to the superficial venous system, which includes the antecubital vein, basilic vein, and cephalic veins. The everlinQ devices are Certification Europe (CE) marked, and the everlinQ 6F system is approved for use in Canada.

Fig. 82.1, Different versions of the EverlinQ device (TVA Medical [Austin, TX]). Shown are the everlinQ ( top ), the everlinQ S ( middle ), and the everlinQ 4 ( bottom ) versions.

Initial Animal Work

A precursor to the everlinQ System called the FLEX system, also a 6F system, was used to create an sutureless arteriovenous anastomosis initially in 40 sheep. In the ovine model, an AVF was successfully created between the external iliac artery and vein in all animal subjects. Long-term follow-up showed healing with an endothelialized anastomosis and no collateral damage with histological examination ( Figs. 82.2 and 82.3 ).

Fig. 82.2, Histological image of the anastomotic site demonstrating no stenosis and a uniform endothelialized fistula between the iliac artery and vein.

Fig. 82.3, Gross image of the fistula created between the iliac artery and vein that demonstrates a well-healed fistula with no fibrosis or scarring.

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