Defibrillation is Tx for life-threatening cardiac dysrhythmias and ventricular fibrillation.

• Delivering a therapeutic dose of electrical energy to the heart, with a defibrillator
• The defib depolarizes a critical mass of the heart muscle, terminates the dysrhythmia, and allows normal sinus rhythm to be reestablished by the SA node (the body's natural pacemaker)

• External, including:
  • AED's (automated external defibrillators), which automate the Dx of treatable rhythms, meaning that lay responders or bystanders can use them successfully with little or no training at all
• Transvenous
• Implanted (implantable cardioverter-defibrillator)

• Life support