Difference Between Cardioversion and Defibrillation (With Table)

  Cardioversion and defibrillation are two terms that are closely related to the heart. These are used when we talk about issues related to the heart, like irregular heartbeats or rhythms, which is also known as arrhythmias. The right knowledge of cardioversion and defibrillation can help save the lives of many people.

Cardioversion vs Defibrillation

The main difference between Cardioversion and Defibrillation is that cardioversion is administered synchronised shocks during are waves or QRS complexes of a cardiac arrest, whereas defibrillation is a random non-synchronised administration of shock waves also during a cardiac cycle. The definition of these two might sound similar, but when we observe closely and understand that they are completely different.

Cardioversion deals with the conversion of arrhythmia to sinus rhythm. There are a lot of related procedures to cardioversion, and everything coming under this category helps in bringing back sinus rhythm. The most important aspect of cardioversion is that they need to be synchronised and not just any random wave.

Defibrillation is a random and non-synchronised administration of shocks that needs to be given during a cardiac cycle. Some indications of defibrillation are ventricular fibrillation, pulseless ventricular tachycardia, and cardiac arrest due to ventricular fibrillation. There are many more things by which the distinction between Cardioversion and Defibrillation can be seen clearly.

Comparison Table Between Cardioversion and Defibrillation

Parameters of Comparison




It is a synchronised administration of shock during QRS complex or R waves of a cardiac arrest.

It is a random non-synchronised administration of shock waves during a cardiac cycle.


Indications for Cardioversion include Atrial Fibrillation, Ventricular tachycardia with a pulse, Supravena tachycardia, etc.

Indications for Defibrillation include Ventricular Fibrillation, Pulseless Ventricular Tachycardia, and cardiac arrest due to or resulting in VF.


Anaesthesia is used in cardioversion almost all the time.

It is advised to perform Defibrillation under sedation.


Energy joules are low.

Energy Joules are high.

Escalated Energy

Escalated for next shock (100J – 200J – 300J – 360J)

No energy escalation for the next shock.

What is Cardioversion?

Cardioversion is the procedure that emphasises on synchronised administration of shock given during are waves of a cardiac arrest or also called, QRS complex of a cardiac arrest. It can be any procedure that helps in the conversion of arrhythmia that is an irregular rhythm of the heart back to a regular rhythm, that is, sinus rhythm. There are two types of cardioversions – chemical cardioversion and electrical cardioversion. Initially, the patient is treated with chemical cardioversion, and if it fails to provide any help, then it is better to move on to electric cardioversion to safeguard the person.

There are many scenarios in which cardioversion is required. Some of these are very common, like chest pain, pulmonary oedema, syncope and hypertension. There are also many situations in which this technique of cardioversion is less frequently used, like atrial fibrillation. This is very important to bring back the heart rhythm to sinus rhythm. The risk of thromboembolic disease is associated with cardioversion of atrial fibrillation, and so it is recommended to undergo anticoagulation at least four weeks after or three weeks before the procedure. Anaesthesia is given to the patient undergoing cardioversion almost all the time. Energy joules also escalated after every shock.

What is Defibrillation?

Defibrillation is referred to as random and non-synchronised administration of shocks given during a cardiac cycle. It is not a very ancient procedure and was first introduced as alternating current Defibrillation to treat ventricular fibrillation in humans in the year 1956. After six years, in 1962, even direct current Defibrillation was discovered.

Indications for defibrillation are ventricular fibrillation, pulseless ventricular tachycardia, and cardiac arrest due to or resulting in ventricular fibrillation. Defibrillation must be performed in conjunction with sedative agents. Defibrillators have the feature of delivering energy in different waveforms that are characterised as monophasic and biphasic. Monophasic defibrillation is known to deliver charge in just one direction, whereas biphasic defibrillation can deliver in one direction for the first half of the shock and then in the electrical opposite direction for the second half of the shock. There are also different portable relatives available that can be worn as a guest and monitor the heart 24/7.

The market is full of varieties when you go out to buy a defibrillator. All of them have their advantages and disadvantages, and therefore it is important to undergo quality research before choosing the right defibrillator for you. Some commonly available defibrillators are Philips heartstart onsite, physio-control lifespan cr2, heart sign samaritan 350p, cardiac science G3 AED fully automatic, and ZOLL AED plus fully automatic.

Main Differences Between Cardioversion and Defibrillation

  1. Cardioversion is an administered synchronised shock given during QR complex or R waves of a cardiac arrest, whereas Defibrillation is a random and non-synchronised administration of shock waves during a cardiac cycle. 
  2. Anaesthesia is used almost all the time in Cardioversion unless there is a special case, while defibrillation is an emergent manoeuvre, and so sedation is only provided when utterly necessary.
  3. Atrial Fibrillation, Supervena Tachycardia, and Ventricular Tachycardia with a pulse are some common indications for Cardioversion. Some common indications for Defibrillation include Ventricular tachycardia without a pulse, Cardiac arrest due to VF or resulting in VF.
  4. Energy Joules are low in cardioversion, whereas Energy Joules are high in Defibrillation.
  5. Energy is escalated for every next shock in cardioversion while it is not escalated in case of Defibrillation.


Due to not having proper knowledge about the two treatments, that is, Cardioversion and Defibrillation, there are many cases in which the patient lacks proper medication. Therefore knowing the difference between the two terms, including their procedure, indications as well as precautions, the right treatment can be given to the patient at the right time. Cardioversion and defibrillation are two procedures that are very beneficial for those who have a close relative or have to deal with people with heart problems frequently.


  1. https://www.sciencedirect.com/science/article/pii/0002914988909654
  2. https://www.sciencedirect.com/science/article/pii/0002914987903523