C
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Not strictly a valve advance, but still quite an amazing story. Shows that the heart can recover somewhat when allowed to rest. I guess it's quite an endorsement for ventricular assist devices (in a roundabout way). For those of us whose hearts were a bit damaged prior to valve replacement, any sort of advance in this area is welcome.
http://news.bbc.co.uk/1/hi/health/4904914.stm
http://news.bbc.co.uk/1/hi/health/4904914.stm