These days defribillators are so advanced that almost anyone can use them. These devices were once usable only to trained paramedics, but now in many parts of the world to use a defibrillator all that is required is that you take a basic CPR course and then a short (four hour) defibrillator course.
Automatic external defibrillators (AEDs) that cost under US$5000 are being outfitted at convenient locations in office buildings, airports and even elementary schools. These ones are battery operated and have voice directions to guide you. The major reason why the defibrillator is now available for public use is that the new devices check the status of the heart and won't let you shock the patient unless he or she is really fibrillating. After all, you really don't want people being shocked accidentally!
Manufacturers claim that use of external defibrillators can improve survival rates 30% in cases of sudden cardiac arrest.
There are also small implantable cardiac defibrillators (ICDs), which are surgically implanted in the heart and produce a shock when they detect fibrillation.
http://enquirer.com/editions/1999/04/16/loc_company-owned.html
http://www.metroactive.com/papers/saratoga.news/02.09.00/defib-0006.html
http://www.advocatehealth.com/healthinfo/articles/heartcare/invasive/icdefib.html