Any good physiology book. Guyton? Costanzo? There are good chapters in most good anesthesia books.
I don't find it as rocket science as respiratory, unless you want to know stuff at the level of m and h gates, in which case Boron should be your friend (although I haven't read it... yet).
There is also a highly rated Pathophysiology of Cardiac Disease book on Amazon. I would not buy a separate book just for cardiac physiology, but that's just me.