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What is Defibrillation?

IVSAT 2024

The treatment for ventricular fibrillation and other life-threatening arrhythmias (abnormal heartbeats) is defibrillation. The heart stops pumping blood to the brain and body when it is in ventricular fibrillation. If not treated immediately, it will induce cardiac arrest and death within minutes. By shocking the heart with electricity, defibrillation restores a regular heartbeat.

When combined with CPR and specialized medical care, rapid defibrillation can save lives. Defibrillation does not treat the arrhythmia's underlying cause. It does not always work, especially in cases of severe, untreated cardiac disease or some end-stage conditions.

Defibrillator Machine

Defibrillators are devices that provide an electric pulse or shock to the heart to restore a regular heartbeat. They're used to prevent or treat arrhythmias, which are irregular heartbeats that are either too slow or too fast. If the heart abruptly stops beating, defibrillators can help restore it. Defibrillators are designed to work in a variety of ways. The goal of automated external defibrillators (AEDs), which are found in many public places, is to save the lives of those who have suffered a sudden cardiac arrest. In an emergency, even inexperienced people can operate these devices. Other defibrillators can help those who are at high risk of dying from a life-threatening arrhythmia. Implantable cardioverter defibrillators (ICDs) and wearable cardioverter defibrillators (WCDs) are two types of defibrillators. ICDs are surgically implanted inside the body, while WCDs are placed on the body. It takes time and effort to adjust to living with a defibrillator, and it's critical to be aware of the risks and issues that can arise.

Types of Defibrillator Machines

1. Manual Defibrillator

A healthcare professional's skill is required for manual external defibrillators. They're utilised in conjunction with an Electrocardiogram, which might be standalone or integrated. The voltage and timing for the electrical shock are manually determined after a healthcare provider assesses the heart rhythm. The majority of these units may be found in hospitals and on select ambulances. During or after cardiac surgery, such as a heart bypass, an internal defibrillator is frequently used to defibrillate the heart. Round metal plates are used as electrodes and come into direct touch with the myocardium. Paddles placed directly on the heart administer the shock in manual internal defibrillators. They're mostly employed in the operating room and, in rare cases, the emergency department during an open heart surgery.

2. Automated External Defibrillators (AED Defibrillator)

Automated external defibrillators (AEDs) are a type of defibrillator designed for use by untrained persons. AEDs have equipment that can analyse cardiac rhythms. As a result, determining whether or not a rhythm is shockable does not necessitate the use of a qualified health expert. AEDs have improved outcomes for abrupt out-of-hospital cardiac arrests by making these units widely available.

Trained health professionals will have more limited use of automatic defibrillators than manual external defibrillators. AEDs do not enhance outcomes in patients with in-hospital cardiac arrests, according to recent studies. AEDs have fixed voltages and do not allow the operator to adjust the voltage based on the situation. AEDs may also cause effective CPR to be delayed. AEDs frequently require the cessation of chest compressions and rescue breathing in order to diagnose rhythm. For these reasons, certain organisations, such as the European Resuscitation Council, advocate that if manual external defibrillators are readily available, they be used instead of AEDs.

AEDs have been widely available in many easily accessible regions because early defibrillation can greatly improve VF outcomes. AEDs have been incorporated into the basic life support algorithm (BLS). They are carried by many first responders, including firefighters, police officers, and security guards.

AEDs are available in two types: completely automatic and semi-automatic. A semi-automatic AED diagnoses heart rhythms and determines whether or not a shock is required. If a shock is recommended, the user must press a button to deliver it. A fully automated AED detects the heart beat and instructs the user to stand back while the shock is delivered automatically. Few types of AEDs have advanced features, like manual override or an ECG display.

3. Cardioverter-Defibrillators

Automatic internal cardiac defibrillators (AICDs), also known as implantable cardioverter-defibrillators (ICDs), are pacemaker-like implants. According to the device's programming, they continuously monitor the patient's heart rhythm and automatically administer shocks for life-threatening arrhythmias. Many current equipments can discriminate between ventricular fibrillation, ventricular tachycardia, and other arrhythmias that are more benign, such as supraventricular tachycardia and atrial fibrillation. Prior to synchronised cardioversion, some devices may attempt overdrive pacing. When ventricular fibrillation is life-threatening arrhythmia, the device is programmed to deliver an unsynchronized shock right away.

In some situations, the patient's ICD may fire frequently or incorrectly. This is a medical emergency since it depletes the device's battery life, gives the patient severe discomfort and worry, and in extreme situations, can even produce life-threatening arrhythmias. Some emergency medical personnel now have a ring magnet to place over the device, which essentially inhibits the device's shock function while still allowing the pacemaker to work (if the device is so equipped). EMS workers may deliver sedation if the gadget shocks regularly but adequately.

A wearable defibrillator is a portable defibrillator which can be worn by risky patients. If VF or VT is identified, the equipment watches the patient 24 hours a day and can immediately deliver a biphasic shock. Patients who are not immediate candidates for ICDs should use this device.

Defibrillator Uses

In cardiac resuscitation, defibrillation is frequently used (CPR). CPR is a procedure that uses an algorithm to restore cardiac and pulmonary function. Only some types of cardiac dysrhythmias, such as ventricular fibrillation (VF) and pulseless ventricular tachycardia, require defibrillation. Defibrillation is not recommended if the heart has fully stopped, as in asystole or pulseless electrical activity (PEA). If the patient is cognizant and has a pulse, defibrillation is not recommended. Electrical shocks administered incorrectly can result in serious dysrhythmias such as ventricular fibrillation.

Out-of-hospital cardiac arrest survival rates are dismal, often less than 10%. In-hospital cardiac arrests have a greater success rate of 20%. The specific heart rhythm of persons who have experienced a cardiac arrest can have a major impact on survival rates. People with a shockable rhythm (such as VF or pulseless ventricular tachycardia) had better survival rates of 21-50 percent compared to people with a non-shockable rhythm (such as asystole or PEA).

Why is Defibrillation Performed?

Your heart is a pump-like muscle that pumps blood around your body. There are two upper chambers (atria) and two lower chambers in this structure (ventricles). Your heart, like other pumps, requires an energy source to work. The energy in your heart comes from an electrical conduction system built into it that transfers electrical signals through the four chambers. To produce a regular heartbeat, electrical signals coordinate the chambers. Certain signal faults result in a disordered, inefficient, quivering rhythm. Defibrillation sends an electrical shock through the heart, causing all of the cardiac cells to contract simultaneously. This brings the heart's abnormal beat to a halt and allows it to resume normal electrical activity. To be effective, defibrillation must be performed within minutes of the onset of a life-threatening ventricular arrhythmia.

Defibrillation is used to treat ventricular arrhythmias that are immediately life-threatening, such as:

  • Ventricular fibrillation is a condition in which your heart's lower chambers, or ventricles, beat so quickly and irregularly that they quiver or shake. Your heart pumps very little or no blood to your brain and body as a result. Without defibrillation, death occurs in five to ten minutes.

  • Without a pulse, ventricular tachycardia occurs when the ventricles beat excessively quickly. The heart's efficiency suffers as a result of this. It lowers the quantity of blood your heart can pump to your brain and other parts of your body. If there isn't enough blood to produce a pulse or you pass out, you'll need to be treated with defibrillation. Without a pulse, ventricular tachycardia can quickly progress to ventricular fibrillation.

How is Defibrillation Performed?

The technique for defibrillation differs based on the type of device. It usually entails the following steps:

  • Until a heart defibrillator is available, the clinician will begin CPR.

  • Two sticky defibrillator electrodes or paddles lubricated with special jelly will be applied to your upper right chest and lower left rib cage area by the provider. The upper right chest and upper left back are two possible positions. A doctor will create a thoracotomy incision in your chest and place the electrodes directly on your heart muscle in rare circumstances.

  • The provider or the AED will assess your cardiac rhythm and, if necessary, shock your heart.

  • The provider or the AED will re-analyze the resulting heart rhythm and, if necessary, administer further shocks. A team of healthcare professionals will offer CPR and advanced life support (ALS) treatments as needed during this period.

Complications of Defibrillation

Defibrillation comes with dangers and potential problems. Defibrillation's life-saving benefits significantly exceed the hazards. The following are some of the risks and potential complications:

  • Burns on the skin

  • Myocardial necrosis (death of heart muscle tissue)

  • Various cardiac arrhythmias include asystole (no heart rhythm, also known as "flatlining"), ventricular fibrillation following pulseless ventricular tachycardia, and other less dangerous arrhythmias.


Defibrillation is a life-saving treatment for cardiac dysrhythmias such as ventricular fibrillation (VF) and non-perfusing ventricular tachycardia (NPVT) (VT). A defibrillator shocks the heart with an electric current (known as a counter-shock). Although the exact mechanism is unknown, this process depolarizes a huge portion of the heart muscle, putting an end to the dysrhythmia. The body's natural pacemaker, located in the sinoatrial node of the heart, is then able to restore normal sinus rhythm. A defibrillator cannot restart a heart that is in asystole (flatline), but it can be treated with cardiopulmonary resuscitation (CPR). Synchronized electrical cardioversion, in contrast to defibrillation, is an electrical shock administered in time with the heart cycle. Cardioversion is used to treat poorly perfusing cardiac dysrhythmias such as supraventricular tachycardia, even if the patient is still severely unwell. Depending on the type of device used or required, defibrillators can be external, transvenous, or implanted (implantable cardioverter-defibrillator). Automated external defibrillators (AEDs) are external machines that automate the detection of treatable arrhythmias, allowing lay responders or bystanders to use them successfully with little or no training.

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FAQs on Defibrillation

1. What is the Purpose of Defibrillation?

Ans: Defibrillator used to provide an electric pulse or shock to the heart to restore a regular heartbeat. They're used to prevent or treat arrhythmias, which are irregular heartbeats that are either too slow or too fast. If the heart abruptly stops beating, defibrillators can help restore it.

2. What is Defibrillation in CPR?

Ans: Defibrillation is a life-saving treatment for cardiac dysrhythmias such as ventricular fibrillation (VF) and non-perfusing ventricular tachycardia (NPVT) (VT). A defibrillator shocks the heart with an electric current (known as a counter-shock).

3. Why Early Defibrillation Matters?

Ans: Because VF, VT, and SCA can strike anyone at any time — in or out of the hospital, even at home – defibrillation devices must be readily available. Improved outcomes require quick access to therapy and high-quality CPR. According to research, victims who receive high-quality CPR and an AED shock before rescue professionals arrive have a higher chance of surviving. It's also critical that defibrillators are simple to operate and provide CPR feedback to rescuers, allowing them to provide CPR that matches the American Heart Association's criteria of high quality and increases a victim's chances of survival.

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