Early results of using Spiral Flow AV Graft: Is it a breakthrough solution to a difficult problem?
Although, the preferred method to create an access is native AV fistula, there is still a significant number of patients where this is not feasible. AV access grafts are used in those patients and their patency rates are far from being ideal requiring frequent interventions to maintain their use. Their failure is usually related to stenosis of the venous outflow due to intimal hyperplasia, near the venous anastomosis of the graft. Neo-intimal hyperplasia may, in part, be a normal cellular response to an abnormal (turbulent) flow environment created by the AV access. Studies have shown that, Spiral laminar flow is the normal pattern of flow in most of the large and medium sized vessels in vivo. The Spiral flow graft has a design that creates a more natural spiral laminar flow at the venous end that is a hypothetically a more friendly hemodynamic environment thus reducing intimal hyperplasia and graft failure. We here report the early results of the largest available series of using the graft in AV access.
Retrospective review of all cases using the Spiral Flow graft for AV access in our institution, Jan 2012 to Jan 2014. Patients selected had no suitable superficial veins for native AV fistula. Patient demographics and comorbidities were recorded. Kaplan Meier curve analysis was used to calculate primary, assisted primary and secondary patency rates in comparison to historic controls of straight ePTFE and heparin bonded grafts for the same indication in our institution. Complications were also recorded.
A total of 38 cases were included. The access site was the arm (24), the forearm (11), and chest wall (3). Two thirds were females, mean age of 60 years and mean follow up of 8 months. At 12 month, the primary, assisted primary and secondary patency rates were 73%, 73% and 79%, respectively. Complications included 4 graft infections; 3 severe steal syndrome, 4 seromas and 2 arm swelling. There was only 1 early graft failure. There was only one early graft failure in less than 30 days in a patient with known hypercoagulable state who was not therapeutic on anticoagulation.
|Spiral AVG||78 ± 8||73 ± 8||79 ± 8|
|Heparin banded||56 ± 8||60 ± 8||59 ± 8|
|Standard ePTFE||38 ± 10||47 ± 10||66 ± 11|
12 month patency rates
Spiral flow grafts are a valid and successful option for AV access. One year results tend to be significantly superior to using straight ePTFE and heparin bonded grafts. This may be explained on the basis of the hemodynamic environment created by the spiral laminar flow and may be a significant contribution to preventing neointimal hyperplasia and hence AV access graft failure.