Hello? Is there a doctor in the house?
A defib is used on a heart in an irregular rhythm. A heart in normal rhythm is a pump, in irregular rhythm it doesn't pump. A defib administers a shock to the heart jolting it back into a normal rhythm.
a stopped heart doesn't have any output. A full auto defib needs a rhythm to administer a shock, as such a stopped heart will not be approved by the machine for a shock.
Perhaps better statement would be a "defibrillator can start (or reset) a heart that is not beating correctly." Normal heartbeats work when electrical impulses move through heart muscle in a coordinated manner. If something interferes with these impulses, then the pumping action of some or all of the heart can be affected in different ways. A defibrillator can only work if the heart is still generating its own impulses. Picture a slap to the face of a hysterical person (in movies, anyway) that momentarily stuns, but then allows the person to get a grip. Unfortunately, it only works sometimes. But the sooner a defibrillator is used, the better chance it has of working. Thus, they are now seen in public places (malls, arenas, etc). One at home may save a life.
The aed does not start someone's heart that has stopped beating.It actually stops a heart for a second that is not beating correctly like v-fib. The heart then hopefully gets back into a normal sinus rhythm. the best analogy is that it is similar to rebooting your computer when it is not working correctly. when you do this you are actually shutting the computer off for a second then when it comes back on the computer is working fine. The aed doesn't always work but it does on many occasions!
A defibrilator can NOT i say again NOT under ANY circumstances be used to start a heart that is not beating. Actually the best way to ensure you will never be able to start a stopped heart is to use a defibrilator it is ABSOLUTELY CONTRAINDICATED FOR CARDIAC ARREST. A defibrilator is useful for fibrilations, flutters or other arrythmias BUT NOT cardiac arrest. To start a heart in cardiac arrest you must treat the cause, such as fluid replacement in hypovolemia etc, and give positive inotropic drugs such as epinephrine or dobutamine and administer heart massage.