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Types of Defibrillator – Overview & Uses

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Defibrillators are critical tools for doctors and surgeons, often crucial in helping to restart a patient’s heart. There are five main types of defibrillators, each with unique features and success rates. AEDs, certain types of pacemakers, and other tools often fall under the technological umbrella of “defibrillator”. 

What is a Defibrillator?

The function of CPR is the keep blood circulating throughout the body when the heart is not online. The function of defibrillation is to re-instate a pulse/reignite the heart’s innate ability to pump blood. 

However, each type of defibrillator is specifically designed for certain situations, so knowing which type to use and when is essential to saving lives.

5 Types of Defibrillators

The five main types of defibrillators are:

Each unique type of defibrillator works in varying conditions. Together, each device works as a toolbox of emergency response tools that save countless lives. 

Automated External Defibrillators (AEDs)

What are they?

Automated External Defibrillators use electric pulses to treat cardiac arrest during the first few minutes of arrhythmia. Once strapped on, the electrode pads begin to detect irregularities. AEDs can identify both ventricular fibrillation and pulseless ventricular tachycardia. If the machine notices either of these irregular heart rhythms, it administers a shock to restore the patient’s pulse. 

When are they needed?

People experiencing cardiac arrest outside of the hospital benefit the most from AEDs. AEDs make it easy for bystanders to help restart someone’s heart as soon as possible. AEDs can be used for adults and children alike. 

Sometimes, like when a patient has a pacemaker, or a medical alert bracelet, using an AED is not advisable. 

Learn more about when not to use an AED here.

What are the benefits?

Since AEDs detect arrhythmia and irregular heartbeats automatically, they are critical tools that even bystanders can use. Many schools, homes, and public places have AEDs handy in case of an emergency. 

AEDs improve a victim’s survival rate drastically over CPR alone, and in many studies, bystanders can save victims before EMS arrives. Recent studies have shown that cardiac arrest survival rates double when bystanders step in to use an AED on the victim, rather than waiting for emergency responders to arrive. 

Advanced Life Support (ALS) Defibrillators

What are they?

Advanced life support defibrillators are heavy-duty resuscitating machines used by medical professionals and paramedics. Older ALS defibrillator models used paddles, which a technician would press against a patient’s chest to administer a shock. 

When are they needed?

Often, ambulances are equipped with ALS devices to monitor and restore a critical patient’s heartbeat on the way to a hospital after the patient has already received CPR and shocks from an AED. Using an ALS on a patient is called advanced resuscitation, which is a key link in the American Heart Association’s Out of Hospital Cardiac Arrest Chain of Survival. 

What are the benefits?

While monitoring the patient’s pulse and delivering shocks as needed, advanced life support defibrillators also monitor the patient’s blood pressure, carbon monoxide levels, and other key medical information. ALS defibrillators stabilize patients by making sure that their heart is pumping blood by delivering shocks routinely. This greatly improves their chances of surviving until reaching the hospital. 

Implantable Cardioverter-Defibrillators (ICDs)

What are they?

Implantable cardioverter-defibrillators are medical devices surgeons implant in a patient’s body. Doctors install ICDs beneath a patient’s collarbone. Thin wires connect to the heart, and the battery-powered device sends an electric shock to the heart if it detects an irregular heartbeat. Newer models also function as pacemakers.

When are they needed?

Typically, patients with ICDs have a history of recurring heart irregularities or heart failure. Doctors only consider implanting these devices in patients with certain potentially life-threatening conditions, such as: 

  • surviving cardiac arrest or a heart attack
  • genetic predisposition to irregular heartbeats
  • a congenital heart defect that impacts the hearts ability to beat sufficiently

What are the benefits?

The primary advantage of an ICD is constant protection from irregular heartbeats, even outside of the hospital. Studies show that ICDs are associated with increased survival rates and decreased mortality in people with genetically-inhereted heart arrhythmias.” — this ties into the listed conditions above and further clarifies when these devices are used for the reader.

Wearable Cardioverter-Defibrillators (WCDs)

What are they?

Wearable defibrillators (also called WCDs) are defibrillation devices that patients wear as vests under their clothes. The sensors in the WCD can detect ventricular arrhythmia. If it does, the WCD administers a shock to treat and restore the wearer’s heartbeat. WCDs are entirely automatic and do not require bystander or medical professional involvement to deliver a life-saving shock. Essentially, WCDs are the external and removable version of an ICD. 

When are they needed?

Like ICDs, WCDs are a treatment approach for patients at risk of dying from an arrhythmia. However, WCDs are usually prescribed to patients who will only need this type of support for a shorter period of time. For example, a patient awaiting a heart transplant might need the WCD’s support until surgery takes place. Or a patient waiting to replace their ICD might need a WCD in the interim. 

What are the benefits?

The main perk of WCDs is that patients get to enjoy physical activities that may be dangerous with an implanted pacemaker. In addition, a conscious patient can prevent unnecessary shocks by interacting with the controls on the vest. With this technology, people with life-threatening conditions can carry on with their daily lives with ongoing protection from sudden cardiac arrest. In patients who do not have ICDs, wearable defibrillators have survival rates of over 90%

Learn more about WCDs

Manual External Defibrillators

What are they?

Like ALS machines, manual external defibrillators are used primarily by technicians with extensive medical training. Unlike AEDs and other devices, manual external defibrillators require the user to select a specific shock frequency and administer the shock at their own designated time. They do not automatically detect the heartbeat of the patient and select the voltage for the user. In other words, it is a fully manual system rather than relying on automatic features.

Manual external defibrillators are usually connected to an electrocardiogram (ECG), a machine that depicts heart activity to medical professionals. 

When are they needed?

Patients experiencing cardiac arrest at the hospital or in an ambulance might be treated with a manual external defibrillator. For example, if someone experiences cardiac arrest outside the hospital, receives CPR and AED shocks, and is picked up by EMS personnel, they might receive shocks from a manual external defibrillator in the ambulance on the way to the hospital. 

Manual external defibrillators are also a great option for babies experiencing cardiac arrest, since the dose of the shock can be so highly customized. 

What are the benefits?

Manual external defibrillators allows medical professionals to customize the shock they deliver to the patient. The ECG the manual external defibrillator is connected to offers medical professionals a more accurate, timely glimpse at the heart’s activity than AEDs can. The provider can then use their expertise to deliver a custom shock based on the ECG, which means the shock is better tailored to the patient’s needs than the kind of shock they might get from an AED. Plus, since a highly-trained technician operates this device, there is a much smaller chance for machine errors,sensor inaccuracies, or technology-related delays. 

The survival rates of patients treated with manual defibrillators are comparable to those treated with AEDs. However, manual defibrillators are usually inaccessible until EMS arrives, meaning they are usually a late-stage tool in treating cardiac arrest. 


Each type of defibrillator works in unique ways, but they all maintain a common goal of regulating the patient’s heartbeat. Whether they’re for ambulance teams, skilled doctors, or everyday people, there is a defibrillation tool for anyone to help save someone’s life. 

Automated external defibrillators (AED) are especially convenient and cost-effective for lay people. Having one in your home could save someone’s life from a cardiac emergency while EMS is on its way. 


What is the difference between a defibrillator and a pacemaker?

A pacemaker is an implantable device that keeps a person’s heartbeat steady throughout their daily activities with a very low dose of electricity. It helps the heart to speed up during physical exertion or keep a heart going when the heart muscle is weakened from something like a heart attack.

A defibrillator, on the other hand, administers a stronger electrical pulse when it detects irregular heart behavior. Instead of a regulator like a pacemaker, a defibrillator is an emergency response device.

Many new pacemakers are dual ICD-pacemaker devices.

Learn more about the difference between ICDs and pacemakers

Learn more about living with an ICD

Learn more about technology that interferes with ICDs and pacemakers

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