Chronic Venous Insufficiency
Chronic venous insufficiency is one of the most widespread diseases that mainly affects women, women / men ratio being two to one. The main cause of this disease is represented by a malfunction of the venous valves in the legs. Due to the fact that venous valves are not closing properly, blood that circulates through the veins of the legs will be unable to overcome gravity and will stagnate at this level leading to edemas and even varicose ulcers. Conventional treatment for chronic venous insufficiency makes use of diureticts and anti-inflammatory drugs.
Researchers from the Fraunhofer Institute for Manufacturing Engineering and Automation IPA in Stuttgart were able to create valve implants for this widespread disease. This implants are created from polycarbonate-urethane (a plastic) and are aimed to treat the cause of chronic venous insufficiency and not just the symptoms, as is the case of drug treatment.
The central nucleus of this implants made by polycarbonate-urethane, 3D droplet dispensing technology which allows scientists to a apply a certain polymer onto a surface without a certain form and in the same time to exploit polymer hardness. 3D droplet dispensing technology is an additive procedure that allows three-dimensional geometries to be created layer by layer using a polymer, explains the leader of the researchers team.
The reason why researchers used polycarbonate-urethane for valve implants is represented by the fact that this material is very flexible and strong and can be easily seen into the surrounding tissue. Another feature of this material is that polycarbonate-urethane can form structures in very thin layers which are ideal for venous valve implants. By using PCU in combination with our 3D dispensing kinematics, we can achieve seamless transitions within the material between six different grades of elasticity and hardness without any breaking points whatsoever. This technique mirrors the design of highly stressed structures in nature. It can't be done using injection molding, explained the scientists.
Polycarbonate-urethane become a venous valve prosthesis by a technique that is using nitrogen and the 3D droplet dispensing tool. Initially, the polymers are dissolved by a solvent and the are placed onto a venous valve prosthetic mold. After this procedure the prosthetic valve is introduced into streams of warm nitrogen, procedure which makes the solvent to evaporate. This step is repeated for several times until venous valve prosthesis is fully coated with droplets of polycarbonate-urethane. Due to the fact that this prosthesis is very flexible, doctors can implant it into a vein of the lower limb by venous catheter passed through the skin.
Venous valve implants represent a step forward in the treatment of chronic venous insufficiency and also represent the first treatment which is treating the cause of the disease and not only the symptoms. In the future researchers want to make their venous valve implants as durable as heart valve implants.