I had a pacemaker for 11 years and the battery was finally draining quicker than usual. Unfortunately, the HMO I belong to in Northern California has a durable materials department that won’t allow the pacemaker to be changed until it has drained down and is in the “end of it’s life” mode. I was at a wedding destination 10 hours away when the pacemaker decided it was time. It was terrible; I could barely walk and had no energy whatsoever. Thank goodness, my husband was there to lean on constantly. We thought I felt that way because I had been having a lot of pain with plantar fasciitis because the tech never told me it was that imminent and I would feel like “crap” (her words afterwords). Lucky I had an appointment for a pacemaker check the day after we came back from vacation and had an emergency replacement within a few days. I feel like my health was put in jeopardy and don’t know if any damage was done to my heart. My life or their profit.
I realize that you have a lot of history with your mother and her pacemaker, but modern pacemakers don't just "die". When the battery voltage drops to a certain level. The pacemaker will go into an "end of life mode" (battery, not person). It's sort of a last ditch conservation mode until the battery can be replaced. What happens then is the pacemaker will fire to a preset pulse rate. It will no longer take into account what the user's heart is doing. The is reported by some to be a very uncomfortable, miserable feeling. However, if your mother is pretty sedentary, she may not notice it as much as someone who is ambulatory.
Many times, pacemaker replacement can be done under local anesthesia. This is not a difficult procedure. Absolutely get another opinion!
I understand the battery replacement is a rather minor surgery. Seems strange to me her doctor would say she is not a candidate "due to her other health problems". I would push for a reconsideration by the doctor as it reads like she may be stuck in bed without the help of the pacemaker. This is not a diagnosis or even a statement from experience, just and encouragement to be sure the doctor does his/her best to keep your mother's quality of life as high as possible.
Is there a reason she is letting the battery die? I am paced most of the time and feel awful when not paced. My own heart rate goes down in the 40s and I feel wobbly, shaky, like I can't even walk. After being paced for 9 years, I am wondering why the pacemaker is not being replaced.