Not to speak for nobog, I think that what he's trying to say - but can't because he may be limited by non-disclosure agreements, - is that similar valves - using plastics or similar materials as leaflets (instead of solid materials like metal or pyrolitic carbon) have probably been tested in labs on non-humans - and developers are still trying to find long lasting, effective alternatives that are more lifelike and may eventually become suitable for safe use for decades.
I can't imagine technologists just siting on their thumbs because current valves work well and provide decades of good performance -- there's a lot of money (in addition to a minor effect - saving lives) - to developing a better alternative. And this involves developing and testing synthetic materials. There's a LOT of wear and tear on any leaflet - and it's awfully damned challenging to come up with ANY material that would last for decades. (Even natural tissue - porcine or bovine valves - have limited lifespans.
(Gruesome thought - for some people with bad valves - instead of heart transplants, what about transplanting valves from the young unfortunates who become organ donors? With these kind of donations - just valves, instead of entire hearts, more than one life can be saved - mitral valve in one person, aortic in another - I said this was gruesome).
Oh - one more thing -- 'blood thinners' do NOT thin blood. They increase clotting time. It's unfortunate that this pair of words has caught on.
