Engineers backed by the National Institute for Biomedical Imaging and Bioengineering (NIBIB) are designing and testing aortic heart valve replacements made of polymers rather than animal heart tissues.
The prototype valve was developed in a collaboration between Stony Brook University, New York, and Polynova Cardiovascular. The valve is a TAVR version of a Polynova polymeric valve designed for surgical aortic valve replacement (SAVR). The valve was made by placing pellets of the raw polymer into a mould under heat and pressure using compression moulding.
Led by NIBIB grantee Danny Bluestein, professor of Biomedical Engineering, Stony Brook University, a team of experts in the dynamics of blood flow in the cardiovascular system has designed and laboratory tested an experimental polymer TAVR valve. It’s hoped the use of polymers will overcome some of the problems with long term use of tissue valves, improving the procedure and outcomes so that it can be reliably offered to more patients of all ages, reducing the need for open heart surgery.
Bluestein said: “We are able to test the valves in the early stages of development using computer models and with mechanical devices that mimic the heart pumping blood through the valve. Our test systems and computer simulations allow us to evaluate a polymer valve and identify specific structural issues affecting performance. Then, we can make the necessary changes, for example in the shape, flexibility, or other aspects of the polymer that would mitigate problems and increase efficiency.”
He also explained that a key advantage of working with polymers is that their shape and properties can be changed, unlike tissues.
Aortic stenosis occurs when the aortic valve of the heart does not open fully as a result of Calcific Aortic Valve Disease (CAVD). CAVD is caused by calcium build up on the valve and can lead to heart failure.
More doctors and patients are opting for TAVR over surgery because the minimally-invasive nature of the procedure can enable quicker recovery. Recovery from SAVR takes several months, while TAVR patients are typically out of the hospital and able to function normally within a few days.
The increase in use of TAVR in younger patients raises a serious issue of the durability of the valves as they are now expected to function for many more years in the patients’ bodies.