I'm sure that your question has already been answered, but I thought I would throw some more clarity on the situation. A pacemaker is simply a beat regulator. It does not allow your heart to go below a certain point or above a certain point depending on whether you have a slow or fast heart rate. These levels are usually set by your cardiologist. A defibrillator, which is sort of what you're describing, acts as an internal "shocker" to try to stimulate your heart back into beating. Although this device would help your heart "re-start", it would not keep you alive because without fresh oxygenated blood being pumped to your brain and other organs they will just simply die like suffocating from lack of oxygen. Classifications for someone being "dead" are different from person to person, and we won't get on that subject because it is a totally different subject