I'm involved in the healthcare (EMR) space. I might be able to give some useful feedback.
EMRs are a difficult product for lean-startups b/c Docs are always pretty busy. That being said there are techie docs which like to discuss the latest and greatest. Have you come across any avenues to reach a broad range of physicians? ImedicalApps (imedicalapps.com) is a pretty good site for this. I have done some guest blogging on their site.