It sounds like your mother's situation is pretty serious. I agree with straydog that you can surf the net and drive yourself crazy. At this point if you are worried about the procedure, you should get a second or third opinion from various doctors (ie. cardiologist, endocrinologist). Then sit down calmly and discuss the pros and cons. Make a decision based on good information, not emotion.
Once you have made a decision, then you need to address some underlying concerns. While not all, many health problems can be helped, if not cured, by a healthy diet and some form of exercise. I'm the poster child for that. At your mom's age, she can look forward to changing her lifestyle and enjoying herself, or going from medication to procedure to next medication and next procedure. After this crisis is over, do some research and determine how she can begin to get herself in as good of shape as possible.