One of my professors at Sick Kids in Toronto did, if I can remember correctly, 5 yrs. general surgery, 3 yrs cardiac and 1 yr pediatric cardiac. I asked him if that's the norm and he said, "Well, you may be able to shorten it a bit, but you probably wouldn't get a very good job."
I know at Toronto, virtually every surgical resident is "strongly encouraged" to pursue a graduate degree as part of their training as the school's goal is to produce academic surgeons, so this can add to the time. But I don't know if this applies in the States as most if not all major centres here that do these types of procedures are attached to universities.