I had my PM implanted almost 9 years ago. It was implanted for sick sinus syndrome (40) and Afib. On my last visit, I was told that I was 100% dependent. I have one yeat plus a few months left on this PM. I've had no problems, feel fine, swim 50 laps every day. Now I am nervoius now, how do they change batteries if I am PM dependent 100%.