READ YOUR ORDERS
Every surgeon will be specific as to what will need to do.
You cannot do chest compressions, the chest is open so it would have to be direct cardiac massage. Only saw that a few times and always by the surgeon.
As far as defib, our surgeons always left a metal retractor in place to hold the sternum open, so there's no way you could use external paddles. We had internal paddles in the bottom drawer of our code carts right along with a chest opening tray that had all kinds of nasty goodness inside.
LVAD/RVAD - READ YOUR ORDERS. In most cases - no compressions. Depending on the type, if the VAD fails, there is usually a hand pump or something as a backup.