What Does a Heart Defibrillator Do?

An implantable cardioverter defibrillator (ICD) is a device that sends an electric shock to the heart during a life-threatening abnormal heartbeat. The shock returns the heart rhythm to normal. An ICD can be a lifesaving device.

This article discusses when someone may need a heart defibrillator, how a heart defibrillator works, and how a heart defibrillator is implanted. It also explains the difference between a heart defibrillator and a pacemaker.

When to Consider a Heart Defibrillator

A healthcare provider may recommend an ICD if you've experienced certain heart emergencies or you have a specific heart condition, including:

• You've had a previous sudden cardiac arrest (heart loses function) due to ventricular fibrillation, a life-threatening fast heart rhythm.
• You're at a high risk for cardiac arrest because you have ventricular arrhythmia, an abnormally fast heart rate that starts in the heart's ventricles.
• Your heart is weak and does not pump blood like it should. Sometimes, these are caused by previous heart attacks, heart failure, or cardiomyopathy.
• You have a genetic health condition.
• You have a heart problem that was present at birth.

How a Heart Defibrillator Implant Works

A traditional ICD is implanted under the skin and below the collarbone. It has a pulse generator about the size of a stopwatch, a battery, and a small computer inside. It also has wires called leads that connect to locations in the heart.

Implantable Cardioverter Defibrillator (ICD)

If your heart has a life-threatening rhythm from the heart's ventricles, the ICD will provide a shock called defibrillation to return the heart rhythm to normal and prevent sudden cardiac arrest. The shock may be startling; some describe the feeling as a punch in the chest, while others may pass out due to the heart rhythm change and not feel it at all. Some people with an ICD never experience the shock.

Subcutaneous ICDs are a type of ICD with leads placed on the skin near the heart rather than routed directly to the heart. Healthcare providers use these in people who may need shocks but are not candidates for a typical ICD due to the risks associated with wires leading to the heart.

Subcutaneous Implantable Cardioverter Defibrillator (S-ICD)

Some people with an ICD also have a device that combines a defibrillator and a biventricular pacemaker to help the heartbeat with better coordination.

A heart defibrillator can help you extend your life and improve your quality of life, although you may have other health conditions that may affect outcomes.

Heart Defibrillator vs. Pacemaker

A heart defibrillator provides electrical shocks to the heart to return it to a normal rhythm in patients with an irregular heartbeat. This also means that the device is monitoring for and suppressing irregular heart rhythms. There are some similarities between a heart defibrillator and a pacemaker, but they aren't the same.

A pacemaker is a device that sends an electrical impulse to the heart when it needs help to pump blood properly. It is commonly used for a slow heartbeat (also called bradycardia) and less for a fast heartbeat (tachycardia). Some pacemakers are implanted internally, while others are implanted externally, mainly if they will only be used temporarily.

Procedure to Implant a Heart Defibrillator

An ICD procedure is typically done at a hospital. Before the surgery, you will receive medicine that makes you relax but does not entirely put you to sleep. You also will receive a local anesthetic at the surgical site.

The surgeon will place a sheath, a plastic tube or catheter, into a blood vessel under your collarbone. Surgeons use the sheath to help insert the ICD lead wire into the blood vessels and the heart.

Once the surgeon inserts the lead wire or wires, they make an incision to insert the ICD generator and attach the lead wire(s) to the generator. Before closing the incision, the medical team tests the device to ensure it works properly.

The entire procedure takes about an hour. You will likely stay in the hospital overnight for monitoring. Although you should be able to return to normal activities quickly, a full recovery may take four to six weeks.

Risks After Implantation

There are some risks associated with insertion of an ICD, including:

• Bleeding where the catheter was inserted or the incision was made
• Blood vessel damage where the catheter was inserted
• An infection where the catheter was inserted or where the incision was made
• A tear to the heart muscle
• The leads coming out of place, which would require another procedure to put them in the correct position
• A collapsed lung

Discuss any concerns you have about these risks with your surgical team. There may be other risks specific to your health conditions.

Electronics, Traveling, and Restrictions

Having a heart defibrillator can be life-changing and lifesaving. However, there are a few precautions to keep in mind, such as:

• When traveling by plane, let security screeners know you have an ICD. If they aren't familiar with an ICD, you may have to use the word "pacemaker." Although airport security detectors are safe for ICDs, the metal in the ICD and the leads may set off the alarm.
• If you must have more security screening before a flight, remind the screener that the magnet in their security wand could disrupt your device's functions if held over it for longer than a few seconds.
• Avoid areas with large magnetic fields, such as auto junkyards that use large magnets to lift vehicles.
• Turn off motors for cars and boats when working on them, as they could create a magnetic field.
• Speak with your healthcare provider before a magnetic resonance imaging (MRI) exam. It is often recommended to avoid them when you have an ICD.
• Be careful around anti-theft or electronic article surveillance used in some stores. They may interact with an ICD, but you can still walk through such detection systems quickly.
• Avoid radio or TV transmitters, high-tension wires, and similar high-voltage and radar machinery.
• If you require other types of surgery by a doctor or dentist, let them know you have a heart defibrillator. You may need help to put the ICD in a particular mode or turn it off during the surgery.
• Always have an ID card, and consider wearing a medic alert bracelet to inform health professionals that you have an ICD.

Summary

An implantable cardioverter defibrillator, or ICD, sends an electric shock to the heart to counteract a life-threatening abnormal heartbeat. It may be an option if you have had a heart attack or sudden cardiac arrest before or if you have a genetic condition that an ICD can help. The procedure to insert an ICD takes about an hour. You usually stay at the hospital overnight to ensure the device works as it should.

Getting back to your normal lifestyle is possible after ICD insertion, although you must follow certain precautions when traveling or around areas or machinery with a magnetic field.