New materials and coatings extend life of vascular implants

Research on new materials and coatings in EUREKA project E! 2866 VASCUCHARGE will extend the life of synthetic vascular grafts from months to years, saving on average €7,000 per operation. As such grafts are used in around 500 out of each million vascular treatments in Europe, the savings could be considerable. Furthermore, the pain and discomfort suffered by patients is significantly reduced, as is the drain on health service resources.

The number of implants used in the surgical treatment of vascular disease has been steadily increasing over the last 20 years, so it is now considered a common procedure. Such tubes replace or bypass part of a blood vessel – principally arteries – and operate in a similar fashion to natural blood vessels.

However, while advances have been made in vascular disease surgery, synthetic implants are still susceptible to thrombosis or clotting, occlusions and infection caused by protein and cell adsorption and coagulation activation. Serious post-surgical problems occur in some 10% of surgical patients, which includes approximately a 2% rate of vascular graft infections. As a result, some grafts have to be replaced after only a few months.

Project partners from Austria and Slovenia concentrated their efforts on small grafts where the problem is particularly acute – those with a diameter less than 6 mm. Improved grafts will diminish the likelihood of complications, so the need for repeat vascular surgical treatments will be greatly reduced.

“Little was known about the mechanisms that cause this undesired protein absorption before our work began,” explains Professor Dr Volker Ribitsch from the Institute of Chemical Process Development and Control at Austrian project partner Joanneum Research.

“We knew that there was a correlation between surface charge, surface energy and the accumulation of bioactive substances. By working closely with our Slovenian partners, we investigated these parameters and other factors, including the structure of the polymer used in the graft and a variety of coatings – such as heparin and collagen – to determine the conditions that can reduce this damaging protein absorption.”

New test device

While studying the grafts, the partners also developed a test device to make the necessary experimental investigations possible. “The new instrument monitors surface properties and protein adsorption on medical devices and provides continuous data,” says Professor Ribitsch. “It will be on the market and available to potential manufacturers in the next year or two.”

The new grafts and coatings require more research but are already promising to reduce replacement operations by up to 50%. When this essential work is complete, the partners will seek industrial collaboration with a medical equipment manufacturer to market the results.

“EUREKA was the ideal framework for the project as the expertise lay beyond the medical devices industry,” adds Ribitsch. “Its bottom-up approach is ideal for such research.” The budget for the project was €0.6 million.