Author(s):
Griffin McNamara
Johnathan Neshiwat
Chris Childers
Jonah Adler

Editor(s):
Tushar Garg, MD

History
Dialysis treatment for chronic kidney disease was first developed by Dr. Willem Kolff in 1943, after various iterations and advances its availability began to grow in 1962 after which it has become a mainstay treatment for patients with chronic kidney disease [1,2]. It is estimated that, in 2021, 15 percent of adults in the United States (approximately 37 million people) have chronic kidney disease, of which 661,000 individuals have renal failure, and 468,000 individuals require dialysis [3,4]. There have been a number of advancements in dialysis treatment since its advent; most notably, the creation of arteriovenous fistulas (AVF) for chronic venous access in 1966 [5].

AVF formation is traditionally performed by vascular surgeons by creating radiocephalic, brachiocephalic, or brachiobasilic transpositions and suturing the anastomoses. According to Dr. Dheeraj Rajan, division head and professor of vascular and interventional radiology at the University of Toronto, “the basic technique of creating an AV fistula has not changed considerably since 1966 when initially described by Brescia and Cimino. The sutured anastomosis also has not significantly changed since initially described by Carrel in 1902” [6]. As a result, patients often require post-creation interventions such as in order to maintain patency and facilitate proper maturation of the fistula. For example, in a 2018 study, patients receiving endovascular AVF placement were found to have an event rate per patient-year of 0.74, compared to 7.22 in patients who received surgical intervention (P<.0001) [7].

In recent years, the FDA has approved two new methods for AV fistula creation using a percutaneous approach. These include the WavelinQ (Beckton Dickinson, NJ) and Ellipsys (Avenu Medical, CA) endovascular arteriovenous fistula devices that use radiofrequency and thermal technologies, respectively, to fuse vessels. In 2014, William Cohn, M.D., vice president and director of Johnson and Johnson Center for Device Innovation at TMC, presented a prototype of the Wavelinq endoAVF System, known as everlinq endoAVF system [8]. In 2018, everlinq was approved by the FDA for marketing alongside the Ellipsys endovascular AVF system [9] (5). Several follow-up studies since the introduction of these technologies have shown that they are associated with fewer additional procedures in the 12 months following the initial procedure, suggesting better outcomes and decreased cost [10,11]. Implementation of endovascular AVF placement is also associated with more rapid maturation of the AVF and decreased time to initiation of dialysis [12].

Current
These two techniques are performed by vascular specialists who use a wire to advance a probe in retrograde fashion through the superficial veins in the upper extremity into the radial/ ulnar artery. A probe is then advanced and uses magnets to align the artery and vein and uses thermal energy or radiofrequency to fuse the arteriovenous anastomoses to create the fistula. This technique has favorable outcomes when compared to the traditional surgical technique. First, this is a minimally invasive procedure, and results in minimal scarring and tissue damage around the fistula. Additionally, the formation of a “side by side” anastamoses lessens stress from blood flow, decreases the risk for vessel wall thickening, and has favorable effects on blood flow [15].

WavelinQ:
WavelinQ was given 510(k) clearance by the FDA in 2018 [13]. WavelinQ is indicated for the creation of an arteriovenous fistula using the concomitant ulnar artery and vein in patients who have chronic kidney disease and need hemodialysis. A minimally invasive approach using WavelinQ is achieved using magnets. WavelinQ allows increased physician flexibility by allowing for AV Fistula creation using the ulnar and radial veins and concomitant arteries [13] . Two catheters are inserted, initially into the brachial vein and artery. Using magnetism, the catheters are aligned and confirmed using fluoroscopy. The venous site contains the electrode which emits a burst of radiofrequency energy that introduces a connection between the arterial and venous system [14] .

Figure 1. WavelinQ AV Fistula creation using either the radial/ulnar artery and vein using magnets and radiofrequency to create a fistula.

Ellipsys:
FDA approved in 2018 [9] and one of two newly approved devices for percutaneous arteriovenous fistula creation, the Ellipsys vascular access system from Avenu Medical utilizes a novel technique in pAVF creation. Like the WavelinQ system, Ellipsys takes advantage of the proximity of the upper forearm deep communicating vein and the proximal radial or proximal ulnar arteries [15]. An alternative to WavelinQ’s magnetic and radiofrequency method, Ellipsys utilizes a combination of thermal energy and ultrasonographic guidance in the creation of pAVF. [14,16].

Figure 2. Various options for AV Fistula creation [12]

Under ultrasound guidance, access is gained to a perforating vein adjacent to the radial artery and punctured into the radial artery. A guidewire is then advanced into the radial artery followed by sheath insertion over the guidewire. The Ellipsys catheter device is then inserted. Once positioned to capture both arterial and venous walls, the Ellipsys device is activated. Simultaneously cutting and fusing adjacent arterial and venous walls using thermal energy, our AV fistula is created. Balloon angioplasty follows pAVF creation to reduce post-anastomotic stenosis [15].

Figure 3. Percutaneous AV Fistula creation using Ellipsys [7].

Impact
Since first described by Brescia and Cimino in 1966, AV fistulas have been at the cornerstone of treatment for patients with chronic renal failure. Often these fistulas serve as a lifeline for these patients. Initially, the surgical placement of an AV fistula was revolutionary and its technology not only extended the life but also the quality of patients with renal disease. However, since 1966, the surgical placement of AV fistulas has not changed much. Open surgical placement of these AV fistulas poses some initial limitations such as needing additional procedures within the preceding 12 months after procedure, slow AV fistula maturation and increased time to initial dialysis.

To further advance the technology of AV fistula placement and provide better outcomes for patients both the WavelinQ and Ellipsys systems have been developed. Both technologies provide a new means for minimally invasive placement of AV fistulas. Each of these systems uses a novel approach to create robust fistulas via minimally invasive techniques. The hope is that this technology will provide a new means to perform AV fistulas placement without the complications seen in open surgical placements. Rather than needing general anesthesia and open surgery AV fistulas can now be placed under minimal sedation and minor surgical intervention.

Recent studies done using the wavelineQ have shown promising results. A recent study comparing the wavelineQ AVFs compared to surgically placed radiocephalic AV fistulas showed that the wavelineQ AVFs showed higher rates of fistula primary patency at 400 days [17]. These results indicate that the use of the wavelineQ prolongs time from initial fistula placement to first thrombosis or any intervention needed for recanalization. For patients, this means that they will have a longer complication free interval after initial placement as compared to surgical AVF creation. These results also indicate that the use of the wavelineQ will increase the time and likelihood of fistula functionality before the need for abandonment. When comparing the WavelineQ to the Ellipsys we see similar results. A study conducted comparing the two showed that the rates of primary patency were equivalent between the two. However, it was noted that the rates of secondary patency in this study favored the Ellipsys [17]. These two single center studies suggest that these new technologies are superior to that of open surgical AF fistula placement in terms of primary and secondary patency.

Not only do both the WavelinQ and Ellipsys provide superior patency but they also provide a superior aesthetic appearance without a scar. This outcome is favorable as it improves patient satisfaction with the procedure. Further, these technologies require less postoperative follow up as no surgical incision care is needed. Finally, the increase in patency and need for intervention shown in the previous studies reduces the post fistula creation cost [18].

In conclusion the development of these two new technologies provides a novel and superior method of placement of AF fistulas. The combination of increased efficacy, reduced costs, and increased patient satisfaction make these technologies a welcome addition to the growing procedural base in interventional radiology.

References:
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