Vascular Flow Technologies Ltd. has announced positive test results for its Spiral Flow arteriovenous graft, which the United Kingdom-based devicemaker claims demonstrates superior efficacy when paired against polytetrafluoroethylene grafts, the standard of care.
The European trial’s midterm results indicate the Spiral Flow AV graft had 18-month primary patency rates of 72 percent while PTFE graft rates were only 36.7 percent, the company said in a news release. Secondary patency was 85.5 percent.
The graft’s technology mimics natural blood flow, providing for better patient outcomes, the devicemaker claims. The grafts were used only if patients were not acceptable candidates for autologous fistula procedures.
The company followed up with patients, carrying out duplex mapping every three months and initiated duplex scanning if there were indications shunt failure might occur. Four patients had shunt occlusions, two of which were treated with thrombectomies, the devicemaker said.
"The results are more than satisfactory, particularly as the patients receiving Spiral Flow grafts were negatively selected," noted Wolfgang Hofmann, M.D., of the Department of Vascular Surgery at Feldkirch General Hospital in Austria. Hofmann also is an investigator of the study that compared primary patency rates for 15 patients receiving Spiral Flow AV grafts with a consecutive series of 87 patients receiving PTFE (polytetrafluoroethylene) grafts. Spiral Flow AV grafts only were used if, according to pre-operative duplex mapping, patients were not suitable for any type of autologous fistula.
Vascular Flow executives said the study results provide strong support for the premise of the Spiral Flow technology. Spiral Flow grafts are designed to encourage a spiral laminal flow within the graft, which replicates the natural flow in blood vessels. This reduces turbulence at the distal (venous) end of the graft, thus reducing shear stress, endothelial activation and platelet activation that precede thrombus formation at the distal anastomosis. The study used duplex mapping to confirm the presence of spiral flow in the grafts.
"We have long known that prosthetic graft failure is a normal tissue response to an abnormal flow environment. It was particularly gratifying to see that changing the flow pattern at the venous aastomosis improves the patency of the graft," Hofmann said.
Vascular Flow Technologies develops and markets devices designed to improve blood flow in compromised or diseased blood vessels, using its proprietary Spiral Laminar Flow technology. The company has two CE-marked and U.S. Food and Drug Administration-approved devices commercialized in Europe and the United States -- the Spiral Flow peripheral bypass graft and the Spiral Flow arteriovenous access graft. The firm's headquarters is located in Dundee, U.K.