"My heart docs say I can go forward with surgeries. I had a stress test a year ago that was ok. My big concern is the rehab stress triggering more antrial tachycardia events which occur intermittently now."

Just thinking about heart issues is stressful in itself, so I understand your concern. If your doctor feels you can handle surgery, I would go with that and try to calm your fears as much as possible. As far as PT, the movements and muscle stretches are slow and deliberate, while sitting or laying down to start with. Make sure your therapist is aware of your cardiac concerns and will pay attention to any complaint you might have during sessions. Some of the exercises need to hold at extreme discomfort in order to stretch to an improved next level, but should stop short of actual pain. Knowing what to expect ahead of time may calm some of your concerns, so be sure to discuss and ask questions of your therapist before your sessions. If you don't think they are listening to you or you just don't "jell" with them, ask for another person. Since you had two successful hip surgeries, you already went through something similar, though knee rehab is a bit more time consuming. Good luck on your surgeries, and be sure to check in after the first one and tell us how it's going.