Douglas Harper's Etymology Dictionary
1940, in reference to heartbeat, from de- + fibrillation "a beating in an abnormal way," especially of the muscles of the heart that contract irregularly in this condition.
Wiktionary
n. the stopping of the fibrillation of the heart in order to restore normal contractions, especially by the use of an electric shock
WordNet
n. treatment by stopping fibrillation of heart muscles (usually by electric shock delivered by a defibrillator)
Wikipedia
Defibrillation is a common treatment for life-threatening cardiac dysrhythmias and ventricular fibrillation. Defibrillation consists of delivering a therapeutic dose of electric current to the heart with a device called a defibrillator. This depolarizes a critical mass of the heart muscle, terminates the dysrhythmia, and allows normal sinus rhythm to be reestablished by the body's natural pacemaker, in the sinoatrial node of the heart.
Defibrillators can be external, transvenous, or implanted ( implantable cardioverter-defibrillator), depending on the type of device used or needed. Some external units, known as automated external defibrillators (AEDs), automate the diagnosis of treatable rhythms, meaning that lay responders or bystanders are able to use them successfully with little or no training.
Usage examples of "defibrillation".
If she ever suffered a killing bout of cardiac arrhythmia, the mere thought of Vess would be more effective at jump-starting her heart than the electrical paddles of a defibrillation machine.