What Caleb Yeung said.....
Usually heat that builds in the Central US makes it's way to the East Coast. but the Atlantic may modify it somewhat.
On the other hand, Bermuda Highs can throw heat at the Northeast, but the Midwest would miss out (depending on the position of the High)
Basically heat waves get locked in place in the Midwest when there is drought. It basically feeds on itself. 2012 was a prime example