Alik Farber, MD, professor of surgery and radiology at Boston University, is set to present the results of a multicenter U.S. study at the 2024 Society for Clinical Vascular Surgery (SCVS) annual meeting (March 16–20) in Scottsdale, Arizona, that will show creating arteriovenous fistulas with a vascular external support system, VasQ, decreases the median time to achieve two-needle cannulation by reducing the need to perform maturation procedures.
The study set out to assess the functional outcomes of fistulas created with an external vascular support device as compared with rigorously matched controls of unsupported fistulas for end-stage kidney disease (ESKD) patients by the same surgeons.
Farber focuses on the unreliable trajectory of unsupported fistula functional success that surgeons grapple with: “Arteriovenous fistulas (AVF), when they work, are much more durable and much better for patients [than central venous catheters or arteriovenous grafts],” he said. “But to work, they require maturation, which means that the vein that is plugged into the artery needs to grow in diameter and thickness. We are asking the body to do this, but the problem is, this doesn’t work all the time. Sometimes the vein may grow in diameter but not in thickness, or it may not grow in diameter and simply grow in thickness. So, the corollary to that is many surgically created fistulas do not mature; some fistulas require procedures to help with maturation, and these may or may not be successful.
“In the ideal world, the best thing for the ESKD patient is the creation of a fistula that, after a certain period of time, say six weeks, is usable 100% of the time without any other interventions. That’s the predictable ideal, but doesn’t happen very often. So, anything that improves outcomes to get us closer to that ideal is going to be a very good thing for our patients,” he added bluntly.
One approach to overcoming this quandary is the concept of external support during surgical fistula creation. The VasQ device is a nitinol-based permanent vascular reinforcement implanted around the artery-vein connection. The device is designed to reduce both hemodynamic and mechanical stress to create more functional fistulas. The device, implanted during the surgical creation of either upper arm or forearm fistulas, guides the remodelling in the juxta-anastomotic region to promote outward wall thickening by maintaining the optimal angle, reducing wall tension and facilitating a more stable, laminar flow profile.
“It appears that externally supporting the fistula and making the fistula take an improved angle has promise in increasing functional patency and decreasing the number of interventions to get to maturation,” Farber told Vascular Specialist.
Six U.S. sites that participated in the VasQ U.S. pivotal study and enrolled more than six patients were eligible to participate in a retrospective chart review of unsupported AVFs to compare them to fistulas that had VasQ support. The cohort for this analysis included 104 ESKD patients with 52 in the unsupported group and 52 in the VasQ group. Both groups were well-matched with no significant differences in baseline parameters, including vessel diameter. The researchers evaluated the functional outcomes of time and intervention rate prior to first use, as well as functional success, which was defined as the proportion of fistulas used for hemodialysis at three and six months after AVF creation.
Farber is expected to present the results showing a nearly 30-day reduction in median time to first use driven by a significantly lower need for maturation procedures in the VasQ group as compared to the unsupported cohort. Additionally, significantly more fistulas in the VasQ cohort achieved functional success by the three-month timepoint. The VasQ cohort also showed a trend toward higher functional success rate at six months, but that finding did not reach statistical significance.
“We’re going to present that the immediate days to first use is typically shorter with VasQ fistulas. The ratio of interventions to first use is also significantly less in the VasQ-supported fistulas and the functional success is higher in this group,” commented Farber, adding that the device is relatively easy to place and doesn’t add significant time to the procedure.
Commenting on the results, he said: “The study offers encouraging evidence for the efficacy of an external vascular support of fistulas, especially in lowering intervention rates and shortening the time to achieving functional success.
“I think it’s exciting that there is new clinical science in this space. There’s a huge opportunity that we have with these patients because the maturation rates are currently 50 to 60%, at best. And that’s a pretty small number. So, there’s a considerable need to improve the maturation rates and I applaud Laminate Medical and other companies that are trying to develop ways to address this issue.”
