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Valve Replacement

Mechanical Bileaflet Valve (St. Jude Medical)

The implantation of artificial heart valves is a rather safe and routine clinical procedure  since more than 40 years. Starting with the first implant of a caged-ball prosthesis by Charles Hufnagel in 1952, numerous valve designs have been developed mainly in order to improve their hemodynamic performance. These designs may be classified in 2 main categories: mechanical and biological valves. Whereas mechanical valves totally consist of synthetic materials, Bioprostheses are at least partially made from biologic material.

The development of mechanical valves started started with caged-ball valves and led over tilting disc to bileaflet prostheses, which still hold a leading market position since the late 70s in an almost unchanged configuration. Their advantages are a good hemodynamic performance, a high durabilty and a rather low complication rate in their clinical application. Although, in spite of their improved hemodynamic performance patients with mechanical heart valves need to be treated with a life long anticoagulation therapy in order to prevent acute thromboses or thromboembolism.

Porcine Bioprosthesis (Medtronic)

Bioprostheses are mainly classified in porcine and pericardial valves. Whereas porcine valves are made from aortic valve leaflets of pigs, the pericardial valves are mainly manufactured from bovine pericardium. Although an anticoagulation treatment is usually not necessary after heart valve replacement with a Bioprostheses, the durabilty of the devices is uncertain. They tend to calcify, biodegrade or fail structurally.

The Cardiovascular Engineering group has a more than 35 year history in research and development of new valve concepts. Whereas the early works focussed on testing of the hemodynamic performance and the durability of existing prostheses, own concepts were developed in later years. I.e., the concept of biomechanical heart valve prostheses with flexibel polymer leaflets was followed in the 80s and 90s and was further developed by the spin off company (ADIAM life sciences). Furthermore, the group was substantially involved in the development of a mechanical trileaflet valve (Triflo Medical).

Mechanical Trileaflet Valve (Triflo)
Biomechanical Polymer Valve (ADIAM)

Percutaneous Valve (CoreValve)

Latest developments aim on a more gentle implantation of the prostheses. They are interventionally applied insted of surgically implanted in the open chest. Therefore, they are integrated into a stent, folded and loaded into an application catheter. The catheter is then shifted through a vessel to the implant position under image guidance. There the valve is realeased, unfolded and anchored, mostly by radial forces only. These valve types are often referred to as "percutaneous valves", as only a small incision through the skin (percutaneous) is needed to access the guiding blood vessel.

As the valves need to be folded, only flexible types are suited for percutaneous valves. In one of its valve projects the CardioVascular Engineering group follows the target to develop a polymer valve modeled on the biomechanical valves as a percutaneous valve. In a similar fashion the polymer valve technology is used to design a venous valve.

In addition, a polymeric valved conduit is developed for reconstruction of the right ventricular outflow tract of new borns.

Contact

Dipl.-Ing. Christian Doose

Tel. +49 241 80 88764

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