The problem is the same as with any organ transplant. The recipient must take many immune-suppressing drugs daily to prevent the body from attacking the organ. Such drugs greatly weaken the defense to other illnesses & diseases, leaving the recipient vulnerable.I don't know anything about heart transplants but I assumed that after having one the person then has a healthy heart and can go about life as usual. Hike, water ski, dance, whatever they did before.
Apparently not? They are so fragile that even a cold will kill them?