The closest thing to do for one year is adult cardiac anesthesia with elective rotations in pediatric cardiac. The new requirements for adult cardiac, now that they are in the ACGME, limit the amount of peds you can do though.
There are about 5 pediatric cardiac programs that you can do after pediatric anesthesia or cardiac anesthesia fellowship, but they aren't really combined programs.
You can also do a cards fellowship then 6 months of peds hearts. That way you are eligible for full TEE certification. Depends on your interests. Rumor has it that peds then peds hearts will be the norm in the future though.