MeSH (full name Medical Subject Headings) is a controlled vocabulary that is widely used in medical information systems.  We’re actively exploring using it in Trip as we believe it can significantly improve our search results.

As far as I can tell it will improve them for two main reasons.  Firstly, it’ll improve our synonyms function as MeSH is great for that.  Secondly, and this is the most exciting aspect for me, is that MeSH is hierarchical. If you do a search for arrhythmia that maps to the MeSH concept of Arrhythmias, Cardiac: