The author could even do something more simple, and try to locate some primary literature on the topic he is discussing above, changes to the beating pattern of the heart. It doesn't need to include a bunch of basic information for it to be a 'steemstem' post, rather just an illustration that the content is based in fact and not just the opinion of the poster with some citations to the information, so anyone who wants to read in more detail has the easy access to do so.