death of husband

my husband died at physical therapy that was prescribed after knee surgery from a work comp fall at work. He had an ekg before surgery and because of that they were going to postpone the surgery. They did the surgery and he's told to start this therapy. while he's going to therapy the nurse who took the ekg keeps calling leaving messages that he should follow up on that ekg. the doctor does not let the therapy department of the orthopedic center know of the ekg hence the therapy becomes a strain for my husband. He's not a complainer and figures he has to do this. He in the meantime plays phone tag with this nurse trying to find out what is on it that she is concerned with. He goes to the therapy, does most of it and is then put on the stair stepper again at which time he collapses from a heart attack. The orthopedic center is one in which there is a surgery center, the doctors offices, and the physical therapy offices. I would like to know why the physical therapists were not aware of the ekg and why the doctor would order that much of a therapy instead of just for the knee or at least keep it very minimum. I would like to know if there is something I should do or if this would even warrant looking into. He was in his mid 50's. The loss of my husband has turned my world upside down and I feel cheated out of even another day I could have had with him. He was found to have heart disease, but was not aware of it nor did he have any problems leading him to believe he had a problem.