Defibrillators and pacemakers help the heart maintain a regular rhythm. Defibrillators deliver a shock if the heart goes into arrhythmia. Pacemakers use electrical impulses to keep the heart from beating too slowly or skipping a beat.

Conditions such as arrhythmia and heart failure interfere with the heart’s ability to circulate enough blood to meet the body’s needs.

A person experiencing this type of heart issue can work with their doctor to decide whether a defibrillator or a pacemaker is the right fit as part of their treatment.

This article discusses the difference between defibrillators and pacemakers, how they work, and their purposes. It also looks at how a person might choose between them and how much they might cost.

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A defibrillator is a device that tracks a person’s heart activity. It delivers an electric shock if it detects an abnormal heart rhythm.

Defibrillation works on irregular rhythms that originate in the lower heart chambers, called ventricles. The two shockable rhythms are ventricular fibrillation and pulseless ventricular tachycardia.

Asystole, or no heartbeat, is not shockable. However, effective CPR can convert asystole into a shockable rhythm.


There are three types of defibrillators:

  • Implantable cardioverter defibrillators (ICD): ICDs are defibrillators that people receive as surgical implants. There is a traditional ICD, implanted in the chest, and a subcutaneous ICD, implanted under the skin below the armpit.
  • Wearable cardioverter defibrillator (WCD): A person wears a WCD similarly to a vest.
  • Automated external defibrillator (AED): AEDs are portable devices that can detect and shock certain irregular heart rhythms.

To implant an ICD, a healthcare professional will perform minor surgery. They can place the ICD intravenously, meaning they move it along a blood vessel and into the chambers of the heart. Alternatively, they can place a wire along the breastbone, using a monitor to guide them.

A pacemaker is an implantable device that stabilizes a person’s heartbeat. It monitors the heart’s activity and sends electrical pulses as needed to regulate its rate and rhythm.

Pacemakers can also help improve the beat synchronization between heart chambers. This helps the heart pump blood more efficiently.


Traditional pacemakers use wires connected to the heart. There are three types of traditional pacemakers:

  • single chamber, which uses one lead attached to the heart
  • dual chamber, which uses two leads on separate heart chambers, one upper and one lower
  • biventricular, which treats heart failure with cardiac resynchronization therapy

It is also possible to get wireless pacemakers. These are the size of a large pill capsule. A healthcare professional implants it into the chamber of the heart using a small tube inserted into a vein.

The heart beats because of electrical signals sent from its sinoatrial (sinus) node. These signals cause the heart muscle to contract so it can pump blood.

Defibrillators and pacemakers both use electricity to interact with the heart’s existing signals to correct weak or irregular heart rhythms.


Each type of defibrillator works in a slightly different way.


ICDs are surgically implanted devices placed in the chest or stomach area.

They give off a low energy shock to slow down or speed up an abnormal heart rate. To correct an irregular or fast heart rate, they deliver a high energy shock.

ICDs have a generator connected to wires that can detect a person’s heart rate. These wires rest inside the chambers of the heart. Other types have wires that rest on the heart.

ICDs can record heart rhythms. This can help a doctor program the device to respond to the specific type of arrhythmia a person has.


WCDs have sensors that attach to the skin. These sensors connect to a unit that monitors a person’s heart rhythm.

They can deliver high or low energy shocks as required depending on the type of arrhythmia.

Before delivering the shock, the WCD will give an alert. A person can turn off the alert and prevent a shock. If a person does not turn off the alert, the WCD will deliver the shock.

A person will need to replace the sensors after each episode.


Sticky pads that contain sensors attach to a person’s chest. These sensors send information about the heart rhythm to a computer in the AED, which analyzes the rhythm. The sensors deliver a shock if a person needs it.


Pacemakers send low energy electrical impulses to the heart. Traditional pacemakers use wires to do this.

A person can adjust a pacemaker’s voltage, pulse time, and rate as needed.

The typical ranges are:

  • 0.1 to 15 volts
  • 0.5 to 25 milliseconds
  • a rate of up to 300 per minute

The wireless pacemaker sends pulses to the right ventricle.

There are a range of heart conditions doctors can treat with defibrillators and pacemakers.


A person may benefit from a defibrillator if they have experienced a cardiac episode or have any underlying conditions that increase the risk of sudden cardiac arrest.

Examples include:


Doctors may recommend a pacemaker to manage:

The type of heart condition a person has will determine whether an ICD or pacemaker is a better choice for an individual.

Is one better than the other?

Newer ICDs often come with with pacemaker functionality. This means they can deliver electrical impulses of varying strengths depending on what the heart needs to restore its typical rhythm.

Pacemakers do not have the ability to shock an immediately life threatening heart rhythm.

People may experience issues with their defibrillator or pacemaker if they are near strong magnetic fields or certain electrical devices.

They should use electrical devices sparingly and keep them at least 6 inches away from their defibrillator or pacemaker.

Devices to limit or avoid include:

A person’s doctor can provide detailed information specific to their defibrillator or pacemaker.

Implant surgery also carries some risks, including:

Device risks include:

  • device failure
  • manufacturer recall
  • lead dislodgement

The cost of a defibrillator or pacemaker can vary depending on a person’s insurance coverage.


Medicare lists the following costs, based on national averages from 2022:

Ambulatory surgical centers Hospital outpatient departments
Total cost$28,254$34,486
Doctor fee$939$939
Facility fee$27,315$33,547
Medicare pays$22,603$32,742
Person pays$5,650$1,743


Medicare lists the following costs, based on national averages from 2022:

Ambulatory surgical centers Hospital outpatient departments
Total cost$8,594$11,150
Doctor fee$531$531
Facility fee$8,063$10,619
Medicare pays$6,875$9,488
Person pays$1,718$1,662

The following are answers to some frequently asked questions about defibrillators and pacemakers.

Can a person get a combined pacemaker/defibrillator?

Some ICDs have a pacemaker feature that can deliver electrical impulses if a person’s heart rate is too slow.

Can a person have a heart attack with a pacemaker or defibrillator?

A person can still have a heart attack while wearing a pacemaker or defibrillator.

A heart attack, or myocardial infarction (MI), happens when a blood vessel blockage cuts off the blood supply to an area of the heart muscle. It can result in the death of some cells in that area.

Pacemakers and defibrillators help correct heart rhythm abnormalities, not blood vessel blockages. So a person can still experience an MI with an implanted cardiac device.

What is the life expectancy of a person with a pacemaker or defibrillator?

Life expectancy can vary according to factors, including the type of cardiac condition a person has, their age at the time of implantation, and any other medical issues they may have.

How painful is a defibrillator shock?

Defibrillator shocks can vary in intensity depending on the activity of the heart.

Low energy shocks may not be detectable or can feel similar to a fluttering sensation in the chest.

High energy shocks are very short but can hurt, similar to a thump or kick in the chest. Prior to a high energy shock, a person may feel arrhythmia.

ICDs and pacemakers send electrical currents to the heart to help it beat correctly. Both devices are surgically implanted and have different functions.

For example, ICDs can deliver a voltage high enough to correct a dangerous arrhythmia. Pacemakers can treat heart failure by helping the heart pump more effectively.

A person’s doctor can help them decide which device best meets their needs.