How Implanted Cardioverter Defibrillators (ICD) Restore Heart Rhythm

An implantable cardioverter defibrillator (ICD), is a small device that delivers an electric shock when the heart rate is irregular or too fast. It is similar to a pacemaker in many ways, yet very different.

This article will cover everything about ICDs and discuss their similarities and differences to pacemakers.

ICD

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Implanted Defibrillator Types

There are four types of implanted defibrillators. The first three types are based on how and where the wires, also called leads, are placed in the heart. These implanted defibrillators are:

  • Single chamber ICD: The wire is attached to the right ventricle.
  • Dual chamber ICD: The wires are attached to the right atrium and right ventricle.
  • Biventricular ICD: The wires are attached to the right atrium, right ventricle, and left ventricle.

The last type of implanted defibrillator is a subcutaneous ICD (S-ICD). The wire is not placed in the heart. Instead, it is placed just under the skin to the left of the breastbone. This type of implanted defibrillator cannot also be used as a pacemaker.

Implantable Cardioverter Defibrillator (ICD)

Implantable Cardioverter Defibrillator vs. Pacemaker

An ICD is a small device about the size of a watch that is surgically placed under the skin. It is connected to wires that are attached to the heart in specific locations. When the ICD detects a life-threatening, fast heartbeat it will give a shock. This shock converts the heart rhythm back to normal.

A pacemaker is also a small device surgically placed under the skin with wires leading to the heart. When a pacemaker detects a person's heart rate is too slow, it will deliver an electrical signal to initiate a heartbeat. It can also be used for heart rates that are too fast.

Many ICDs can also be used as pacemakers. However, a pacemaker cannot be used as an ICD.

Why Do I Need an Implantable Cardioverter Defibrillator?

A healthcare provider may recommend getting an ICD if there is a risk of developing a life-threatening irregular ventricular heart rhythm like ventricular fibrillation or ventricular tachycardia. Many different health conditions can cause the heart to develop this kind of irregular rhythm. They are:

How Does an Implantable Cardioverter Defibrillator Work?

An ICD is a device with two primary components:

  • The pulse generator contains the components that detect the electrical activity of the heart and the battery.
  • The wires connect the heart to the pulse generator.

When the ICD detects an abnormal heart rhythm, it will send a jolt of electricity through the wires and to the heart. This shocks the heart and restores a normal heart rhythm.

What Does an ICD Shock Feel Like?

An ICD shock can be described as feeling startling, jolting, or even a kick in the chest. It is not painful. However, the sudden jolt in the chest can feel unsettling.

How Do I Prepare for the Procedure?

An ICD procedure requires a bit of preparation during the days leading up to the surgery.

A healthcare provider will discuss all the pre-procedural instructions over the phone or in person beforehand. These instructions may include stopping blood thinners and fasting the night before and the morning of the procedure. Not following pre-procedural instructions can cause the ICD insertion to be delayed.

You may be given a special soap to wash before the procedure. This will help reduce bacteria on the skin and minimize the risk of infection.

Some people will need to take an antibiotic before the procedure. This will be covered in the pre-procedural instructions.

What Happens During the Procedure?

ICD insertion is typically an outpatient procedure but may be part of someone's hospital stay. The procedure itself generally follows these steps:

  • Get ready for the procedure by changing into a hospital gown and removing all jewelry.
  • A healthcare provider will insert an intravenous (IV) line for medications and fluids.
  • Move into the procedural room, where there will be a table to lay flat on your back.
  • Monitors like electrocardiogram (ECG) patches, pulse oximetry, and respiratory monitoring will be attached.
  • Medications will be given through the IV to help you relax but typically people stay awake during the procedure.
  • The chest will be cleaned and the insertion site will be numbed.
  • An incision will be made in the skin under the collarbone on the left side.
  • A line called an introducer will be placed into a blood vessel to move the ICD wire into the heart.
  • The ICD wire will be placed into the necessary locations and tested.
  • The pulse generator will be placed under the skin and attached to the wires.
  • The incision will be closed with stitches and a dressing will be applied.

What Are the Risks Associated With an Implanted Defibrillator?

As with any surgery, there are risks. The risks that are specific to an ICD are:

A healthcare provider may need to change the ICD settings if it is shocking at the wrong times or not shocking when it should be. This can be done at the healthcare provider's office and does not require another procedure.

Learn more: Implantable Cardioverter Defibrillator Complications

What Happens After the Procedure?

After an ICD placement, someone typically stays in the hospital for one day.

After surgery, a healthcare provider may ask you to reduce the amount of movement on the side where the ICD was placed. This can include not lifting anything more than 10 or 15 pounds, no twisting, no raising your arms overhead, and no pushing or pulling for two to three weeks.

In most cases, people can return to full activities within four to six weeks after ICD placement.

A healthcare provider should give you a card with all the information about the ICD and who to contact in an emergency. This card should always be kept with you in a wallet or another safe spot.

What Is the Long-Term Outlook?

The long-term outlook for someone with an ICD is positive. An ICD will help them convert back to their normal rhythm without intervention from a healthcare provider.

People with ICDs must attend regular follow-up visits to ensure the device works properly. During these visits, the healthcare provider will determine how often the ICD has delivered a shock, make sure it senses the heart rhythm correctly, and see how much battery life is left.

Living With an ICD

In many ways, people who live with an ICD can carry on with life as they did before their surgery. However, there are a few things that do need to change, which are listed below:

  • Inform security guards that you have an ICD before going through metal detectors.
  • Avoid large magnetics and magnetic fields
  • If you need an magnetic resonance imaging (MRI), contact the healthcare provider who placed your ICD to ensure that is permissible.
  • Do not place a heating pad over an ICD.
  • Do not use transcutaneous nerve stimulation (TENS) therapy.
  • Avoid activities that would cause a blow or trauma to the chest.
  • Tell healthcare providers about your ICD before surgery or other procedures.
  • Keep cell phones out of chest pockets

When to Contact a Healthcare Provider

Contact a healthcare provider if you have the following symptoms or concerns:

  • Signs of an infection: fever or chills, redness, or discharge at the ICD insertion site.
  • Chest pain
  • Dizziness
  • Nausea or vomiting
  • Heart palpitations
  • If the ICD pulse generator feels loose or that it is moving under the skin

Summary

An ICD is a device used to return someone's heart rhythm back to normal. The device delivers an electrical shock when it senses a life-threatening arrhythmia. Many ICDs also work as pacemakers and can keep the heart rate from getting too low. A healthcare provider will discuss all the benefits and risks of an ICD to help you determine the best treatment for your situation.

5 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. MedlinePlus. Implantable cardioverter defibrillator.

  2. University of Michigan Health. Implantable cardiac defibrillators (ICDs).

  3. MedlinePlus. Heart pacemaker.

  4. American Heart Association. Implantable cardioverter defibrillator (ICD).

  5. Johns Hopkins Medicine. Implantable cardioverter defibrillator (ICD) insertion.

Patty Weasler

By Patty Weasler, RN, BSN
Patty is a registered nurse with over a decade of experience in pediatric critical care. Her passion is writing health and wellness content that anyone can understand and use.