HIStalk has Healthcare IT News and Gossip http://histalk2.com/
But it's not forum style like HN.
You can always create one yourself - check out HelloBox - http://hellobox.co
Over the years many people have tried building sites like this. None of them have ever worked out.
No, you should build one.
I've been looking for this, too. We have reddit.com/r/healthtech which I moderate but it's not that active right now. Trying to make it more active. :)
Also reddit.com/r/medicine but that is kind of more clinicians and less health tech. There's also reddit.com/r/telemedicine.
Personally I wish there was a way to sort HN via topic, so you could get all the medical news easily separated.
(am a telemedicine nurse at a health tech startup)
There's also RockHealth which you can follow on facebook but they kind of feel scammy imo and generally seem to only promote their own companies. Also you can sort by healthtech on techcrunch: http://techcrunch.com/tag/healthtech/