Thanks for your suggestion, LivingInHope -- I'll be sure to pass it along.
In the meantime, you might want to try using the search box in the Dysautonomia forum itself, entering the term "Tachycardia".
You can also use the main search box at the top of any page and enter your search term as well as the forum name (e.g., "Tachycardia Dysautonomia"). This has the added benefit of locating posts that mention Tachycardia and Dysautonomia in other forums:
http://www.medhelp.org/search?utf8=%26%23x2713%3B&query=tachycardia+dysautonomia
Claire