Implantable Cardioverter Defibrillator (ICD)

What is an implantable cardioverter defibrillator?

An implantable cardioverter defibrillator (ICD) is a device that fixes life-threatening irregular heart rhythms (arrhythmias). It constantly monitors your heart. If it senses that your rhythm is one of the abnormal, life-threatening ones, it sends an electrical shock to your heart to correct it. Many ICDs have a built-in pacemaker, too.

A surgeon places an ICD under the skin on your chest. It has a pulse generator and a thin wire called a lead. You may have more than one lead if the ICD is also meant to function as a pacemaker. The pulse generator is about the size of a stopwatch. It contains a battery and electrical circuits that read your heart’s electrical activity. The leads go into your heart chambers to monitor your rhythm and deliver a shock if need be.

A subcutaneous ICD is a different type of ICD. It has a thin wire that travels under your skin to the outside of your heart. Its purpose is to deliver a shock to correct dangerous heart rhythms if they occur.

ICDs can:

• Correct dangerous arrhythmias
• Prevent sudden cardiac arrest
• Record info about your heart’s function to help your cardiologist recommend treatments

Other names for an ICD include:

• Automatic implantable cardiac defibrillator (AICD)
• Internal cardiac defibrillator
• “Shock box”

You may need an ICD if you’re at high risk of sudden cardiac death from an abnormal heart rhythm. Conditions that can cause this include:

• Previous sudden heart attack or cardiac arrest
• Ventricular tachycardia
• Ventricular fibrillation
• Heart failure with reduced ejection fraction
• Hypertrophic cardiomyopathy
• Brugada syndrome
• Certain types of congenital heart disease
• Long QT syndrome, in certain cases

How should I prepare for an ICD procedure?

Before you get an implantable cardiac defibrillator, your healthcare provider may ask you to:

• Get blood tests, urine tests and an electrocardiogram to ensure you’re healthy enough for the procedure
• Get an echocardiogram to understand why you may need an ICD
• Tell them if you have any blood disorders or take blood thinners
• Report any allergies to contrast dye or iodine
• Tell them if you have asthma, diabetes, kidney disease or any other medical conditions
• Fast for several hours before the procedure (not eat or drink anything except water)

What happens during an ICD procedure?

The type of procedure you have depends on your health and other treatments you need at the same time.

The transvenous approach is the most common for ICD implantation. It involves a small incision (cut) near your collarbone. Your healthcare provider threads the leads through veins to get to your heart. In some cases, implantation requires open-heart surgery.

ICD implantation processes can vary widely. But in general, your provider will:

1. Give you local anesthesia with an injection to numb the skin near your collarbone, or they may give you general anesthesia through an IV to put you to sleep
2. Make an incision near your collarbone, chest or abdomen (belly)
3. Access your subclavian vein and put the wires into your heart chambers
4. Place the ICD under your skin
5. Connect the lead to your heart and the ICD
6. Test the device and the wires to ensure they’re connected correctly and working well
7. Close the incision
8. Test the system again before sending you to recovery

The procedure typically takes a couple of hours.

What are the advantages of this procedure?

An ICD can treat life-threatening arrhythmias and sudden cardiac arrest. It can also provide important information about your heart to your cardiologist.

What are the risks or complications of this procedure?

ICD implantation is generally safe. But as with any surgery, the procedure comes with risks, including:

• Bleeding or bruising
• Collapsed lung (pneumothorax)
• Damage to blood vessels from the leads
• Device malfunction
• Device-related infection
• Infection of the incision site
• Movement of the device, which can tear internal tissue
• Swelling
• Shocks in response to other rhythms that aren’t life-threatening

What happens after this procedure?

After ICD implantation, you may feel tired and sore, especially near the incision. Your healthcare provider may suggest pain medications to make you more comfortable.

Many people go home the day after surgery. Depending on your health and the type of procedure you had, you may have to stay in the hospital for a few days.

Before you go home, your healthcare provider may test the ICD system again.

How many shocks will an ICD deliver?

Most people need only one shock to restore a normal heart rhythm. But you may get two or more shocks in 24 hours. Your provider can adjust the frequency and intensity of shocks depending on the situation.

You should let your provider know if you have any shocks. It could mean you’re having a cardiac emergency or that the ICD isn’t functioning properly.

What should I know about living with an ICD?

If you have an ICD, carry a card in your purse or wallet to alert emergency personnel. This will help them care for you if you have a medical emergency and can’t communicate.

Similarly, you should tell all your healthcare providers about your ICD. This includes dentists and imaging technicians. They may use equipment that can interfere with an ICD’s function.

What should I avoid with an ICD?

Strong magnetic fields and some technology can interfere with an ICD’s function. Ask your healthcare provider if you should avoid or minimize:

• Antitheft systems at retail stores and metal detectors at airports
• Arc welding equipment
• Cellphones (keep yours at least 6 inches away from your ICD)
• Citizen’s band (CB) radios and amateur “ham” radios
• Electric fences, like invisible fences for pets
• Jumper cables and portable car battery chargers
• Machinery that contains magnets, like those that lift vehicles in a junkyard
• MRI machines
• Powerful stereo speakers
• Some medical alert systems

When should I call my healthcare provider?

Tell your healthcare provider if you develop any signs of infection, like:

• Bleeding or other fluids (like pus) coming from the incision
• Fever or chills
• Pain that’s getting worse or isn’t getting better with time
• Redness or swelling that doesn’t improve

Get medical help immediately if you receive several shocks from your ICD in a short time.

What does an ICD shock feel like?

An ICD can be programmed to give low-energy or high-energy shocks. A low-energy shock can feel like a flutter or thump in your chest. High-energy shocks can be painful for a moment, like a blow to the chest.

How long does an implantable cardioverter defibrillator last?

ICD batteries last up to seven years. But this can vary depending on how often you’re receiving shocks. Your healthcare provider should check your ICD every three to six months.