Editing Defibrillation (section)

== Types ==
{{more citations needed section|date=August 2014}}

=== Manual models ===
Manual external defibrillators require the expertise of a healthcare professional.<ref name="Beaumont" /><ref name="FDA" /> They are used in conjunction with an [[electrocardiogram]], which can be separate or built-in. A healthcare provider first diagnoses the cardiac rhythm and then manually determine the voltage and timing for the electrical shock. These units are primarily found in [[hospital]]s and on some [[ambulance]]s.  For instance, every [[National Health Service|NHS]] ambulance in the [[United Kingdom]] is equipped with a manual defibrillator for use by the attending paramedics and technicians. {{Citation needed|date=December 2016}} In the [[United States]], many advanced [[Emergency medical technician|EMTs]] and all [[paramedics]] are trained to recognize lethal arrhythmias and deliver appropriate electrical therapy with a manual defibrillator when appropriate. {{Citation needed|date=December 2016}}

An internal defibrillator is often used to defibrillate the heart during or after cardiac surgery such as a [[heart bypass]]. The electrodes consist of round metal plates that come in direct contact with the myocardium. Manual internal defibrillators deliver the shock through paddles placed directly on the heart.<ref name="Tintinalli" /> They are mostly used in the [[operating theater|operating room]] and, in rare circumstances, in the emergency room during an [[thoracotomy|open heart procedure]].

=== Automated external defibrillators ===
{{main|Automated external defibrillator}}

Automated external defibrillators (AEDs) are designed for use by untrained or briefly trained laypersons.<ref name="PowellJ" /><ref name="ThePublicAccessTrial" /><ref name="Yeung" /> AEDs contain technology for analysis of heart rhythms. As a result, it does not require a trained health provider to determine whether or not a rhythm is shockable. By making these units publicly available, AEDs have improved outcomes for sudden out-of-hospital cardiac arrests.<ref name="PowellJ" /><ref name="ThePublicAccessTrial" />

Trained health professionals have more limited use for AEDs than manual external defibrillators.<ref name="ChanPS" /> Recent studies show that AEDs does not improve outcome in patients with in-hospital cardiac arrests.<ref name="ChanPS" /><ref name="PerkinsGD" /> AEDs have set voltages and does not allow the operator to vary voltage according to need. AEDs may also delay delivery of effective CPR. For diagnosis of rhythm, AEDs often require the stopping of chest compressions and rescue breathing. For these reasons, certain bodies, such as the European Resuscitation Council, recommend using manual external defibrillators over AEDs if manual external defibrillators are readily available.<ref name="PerkinsGD" />

As early defibrillation can significantly improve VF outcomes, AEDs have become publicly available in many easily accessible areas.<ref name="ChanPS" /><ref name="PerkinsGD" /> AEDs have been incorporated into the algorithm for [[basic life support]] (BLS). Many [[certified first responder|first responders]], such as firefighters, police officers, and security guards, are equipped with them.

AEDs can be fully automatic or semi-automatic.<ref name="Physio-Control" /> A semi-automatic AED automatically diagnoses heart rhythms and determines if a shock is necessary. If a shock is advised, the user must then push a button to administer the shock. A fully automated AED automatically diagnoses the heart rhythm and advises the user to stand back while the shock is automatically given. Some types of AEDs come with advanced features, such as a manual override or an [[ECG]] display.

=== Cardioverter-defibrillators ===
[[Implantable cardioverter-defibrillator]]s, also known as automatic internal cardiac defibrillator (AICD), are implants similar to [[artificial pacemaker|pacemakers]] (and many can also perform the pacemaking function). They constantly monitor the patient's heart rhythm, and automatically administer shocks for various life-threatening arrhythmias, according to the device's programming. Many modern devices can distinguish between [[ventricular fibrillation]], [[ventricular tachycardia]], and more benign arrhythmias like [[supraventricular tachycardia]] and [[atrial fibrillation]]. Some devices may attempt overdrive pacing prior to synchronised cardioversion. When the life-threatening arrhythmia is ventricular fibrillation, the device is programmed to proceed immediately to an unsynchronized shock.

There are cases where the patient's ICD may fire constantly or inappropriately. This is considered a [[medical emergency]], as it depletes the device's battery life, causes significant discomfort and anxiety to the patient, and in some cases may actually trigger life-threatening arrhythmias. Some [[emergency medical services]] personnel are now equipped with a ring [[magnet]] to place over the device, which effectively disables the shock function of the device while still allowing the pacemaker to function (if the device is so equipped). If the device is shocking frequently, but appropriately, EMS personnel may administer sedation.

A [[wearable cardioverter defibrillator]] is a portable external defibrillator that can be worn by at-risk patients.<ref name="Zoll" /> The unit monitors the patient 24 hours a day and can automatically deliver a biphasic shock if VF or VT is detected. This device is mainly indicated in patients who are not immediate candidates for ICDs.<ref name="Adler" />