Monitoring the durability of valve replacements using PET scans

Bio prosthetic valve thrombosis

Nearly 9 out of 10 heart valve replacements use valves made from human or animal tissue (bioprosthetic valves). However, these valves do not last for ever and can fail. Recent evidence has suggested that a major contributor to early failure could be blood clots forming on the valve, causing it to degenerate. In this study, Professor Newby’s team plans to test whether a scanning technique called positron emission tomography (PET) can be used to identify when and where these blood clots form. PET uses radioactive ‘tracers’ to track molecules within a tissue, which can then be seen on a scan. In this project they will test a blood-clot-specific tracer, called 18F-GP1. This tracer has a strong attraction for a molecule called glycoprotein IIb/IIIa receptor that is present on platelets – the cells responsible for forming a clot. They plan to use the tracer to identify early valve clots in 80 people over the age of 50 who have had a bioprosthetic aortic valve replacement. They hope to identify the presence and amount of clotting on prosthetic valves and use this to guide treatment with blood-thinning drugs. If successful, PET scans could be used to flag when treatment is needed to extend the lifespan of heart valves.