What is an implantable cardioverter defibrillator?

An implantable cardioverter defibrillator (ICD) is a small electronic device connected to the heart. It is used to continuously monitor and help regulate potentially fast and life-threatening electrical problems with the heart.

A transvenous or “traditional” ICD, about the size of a stopwatch, is implanted under the skin just below the collarbone. It consists of a pulse generator and wires, called leads. The pulse generator contains the battery and a tiny computer. One or more lead wires connect the pulse generator to specific locations in the heart.

The ICD responds to irregular life-threatening heart rhythms from the lower chambers of the heart with pacing that corrects a fast rhythm and promotes a normal heartbeat, or a shock (defibrillation) that resets the heart rhythm to prevent sudden cardiac arrest. An ICD also records and stores information about your heart rhythm and therapies delivered by the ICD for your doctor to review.

Most people are unaware when the ICD is pacing the heart. But, a defibrillation shock is described by many as feeling like a "kick in the chest."

An ICD can also be programmed to work as a basic pacemaker as needed. Sometimes after a shock is delivered, the heart may beat too slowly. The ICD has a "back-up" pacemaker, which can stimulate the heart to beat faster until the normal heart rhythm returns. The ICD can act as a pacemaker any time the heart rate drops below a preset rate.

For those patients who do not require either “back-up” pacing or Anti-Tachycardia Pacing (ATP), a Subcutaneous Implantable Defibrillator (S-ICD) is available. It allows for the delivery of high-energy shocks while avoiding the potential risks and complications associated with leads that traverse the veins leading to the heart.

Why might I need an implantable cardioverter defibrillator?

You may need an ICD if you have survived sudden cardiac arrest due to ventricular fibrillation, or have fainted due to ventricular arrhythmia, or if you have certain inherited heart conditions.

An ICD is generally needed for those at high risk of cardiac arrest due to a ventricular arrhythmia. This includes people with heart failure who have problems with the contraction of the heart, such as abnormal left ventricular ejection fraction.

There may be other reasons for your doctor to recommend an ICD.

What are the risks of an implantable cardioverter defibrillator?

Possible risks of ICD insertion include:

• Bleeding from the incision or catheter insertion site

• Damage to the blood vessel at the catheter insertion site

• Infection of the incision or catheter site

• Tearing of the heart muscle

• Collapsed lung

• Dislodging of the leads requiring another procedure to reposition the leads

If you are pregnant or think that you could be, or are currently breastfeeding, tell your healthcare provider.

If you are allergic to or sensitive to any medicines or latex, tell your healthcare provider.

Lying still on the procedure table for the length of the procedure may cause some discomfort or pain.

There may be other risks depending on your specific medical condition. Be sure to discuss any concerns with your healthcare provider before the procedure.

How do I get ready for an implantable cardioverter defibrillator?

• Your doctor will explain the procedure to you and ask if you have any questions.

• You will be asked to sign a consent form that gives your permission to do the test. Read the form carefully and ask questions if something is not clear.

• Tell your doctor if you are sensitive to or are allergic to any medicines, iodine, latex, tape, or anesthetic agents (local and general).

• You will need to fast for a certain period before the procedure. Your doctor will tell you how long to fast, usually overnight.

• If you are pregnant or think that you could be, tell your doctor.

• Tell your doctor of all medicines (prescription and over-the-counter) and herbal or other supplements that you are taking.

• Tell your doctor if you have heart valve disease, as you may need to take an antibiotic before the procedure.

• Tell your doctor if you have a history of bleeding disorders or if you are taking any blood-thinning medicines (anticoagulants), aspirin, or other medicine that affect blood clotting. You may be told to stop some of these medicines before the procedure.

• Your doctor may request a blood test before the procedure to see how long it takes your blood to clot. Other blood tests and chest X-ray may be done as well.

• You may get a sedative before the procedure to help you relax.

• Based on your medical condition, your doctor may request other specific preparation.

How is a cardioverter defibrillator implanted?

Having an ICD implanted may be done on an outpatient basis or as part of your stay in a hospital. Procedures may vary depending on your condition and your doctor’s practices.

Generally, an ICD insertion follows this process:

• You will be asked to remove any jewelry or other objects that may interfere with the procedure.

• You will be asked to remove your clothing and will be given a gown to wear.

• You will be asked to empty your bladder before the procedure.

• An intravenous (IV) line will be started in your hand or arm for injection of medicine and fluids, if needed.

• You will be placed on your back on the procedure table.

• You will be connected to an electrocardiogram (ECG) monitor that records the electrical activity of the heart during the procedure using. Your vital signs (heart rate, blood pressure, breathing rate, and oxygenation level) will be monitored during the procedure.

• The surgical site is cleaned. In some cases, hair may be shaved or clipped.

• Large electrode pads will be placed on the front and back of the chest.

• You will receive a sedative in your IV before the procedure to help you relax. However, you will likely remain awake during the procedure.

• The ICD insertion site will be cleansed with antiseptic soap.

• Sterile towels and a sheet will be placed around this area.

• A local anesthetic will be injected into the skin at the insertion site.

• Once the anesthetic has taken effect, the doctor will make a small incision at the insertion site.

• A sheath, or introducer, is inserted into a blood vessel, usually under the collarbone. The sheath is a plastic tube through which the ICD lead wire will be inserted into the blood vessel and advanced into the heart.

• It will be very important for you to remain still during the procedure so that the catheter does not move out of place and to prevent damage to the insertion site.

• The lead wire will be inserted through the introducer into the blood vessel. The doctor will advance the lead wire through the blood vessel into the heart.

• Once the lead wire is inside the heart, it will be tested to verify proper location and that it works. There may be 1, 2, or 3 lead wires inserted, depending on the type of device your doctor has chosen for your condition. Fluoroscopy, (a special type of X-ray that will be displayed on a TV monitor), will be used to position the lead.

• For subcutaneous ICDs, one or two small incisions are made near the top and bottom of the sternum or breast bone. The lead wire is then tunneled underneath the skin next to the sternum and from the sternum to the incision on the left side of the chest.

• The ICD generator will be slipped under the skin through the incision (just below the collarbone for traditional ICDs and on the left side of the chest for S-ICDs) after the lead wire is attached to the generator. Generally, if you are right-handed, the device will be placed in your upper left chest. S-ICDs are implanted on the left side of the chest near the heart. If you are left-handed, or have a contraindication to a left-sided device a traditional ICD can be placed in your upper right chest.

• The ECG will be observed to monitor ICD function. Certain tests may then be done to assess the device function.

• The skin incision will be closed with sutures, adhesive strips, or special glue.

• A sterile bandage or dressing will be applied.

What happens after an implantable cardioverter defibrillator?

In the hospital

After the procedure, you may be taken to the recovery room for observation or returned to your hospital room. A nurse will monitor your vital signs.

Tell your nurse right away if you feel any chest pain or tightness, or any other pain at the incision site.

After the period of bed rest has been completed, you may get out of bed with help. The nurse will help you the first time you get up, and will check your blood pressure while you are lying in bed, sitting, and standing. Move slowly when getting up from the bed to avoid any dizziness from the period of bed rest. You will be able to eat or drink once you are completely awake.

Your arm may be in a sling for a day or so. How long you will need to wear a sling will depend on your provider. Some people are asked to wear it at night while they sleep after the first couple of days but can take it off during the day.

The insertion site may be sore or painful, and pain medicine may be given if needed.

After the procedure, a chest X-ray is often done to check the lung and make sure the systems are stable.

Your doctor will visit with you in your room while you are recovering. The doctor will give you specific instructions and answer any questions you may have.

Once your blood pressure, pulse, and breathing are stable and you are alert, you will be taken to your hospital room.

If the procedure is done on an outpatient basis, you may be able to leave after you have completed the recovery process. However, it is common to spend at least 1 night in the hospital after ICD implantation for observation.

Arrange to have someone drive you home from the hospital after your release.

At home

You should be able to return to your daily routine within a few days. Your doctor will tell you if you need to take more time in returning to your normal activities.

Avoid lifting or pulling on anything for a few weeks. You may be told to limit movement of the arm on the side that the ICD was placed, based on your doctor's preferences.

You will most likely be able to resume your usual diet, unless your doctor tells you differently.

Keep the insertion site clean and dry. You will be given instructions about bathing and showering.

Your doctor will give you specific instructions about driving. You will not be able to drive until your doctor says it's OK. These limitations will be explained to you, if they are applicable to your situation.

You will be given specific instructions about what to do the first time your ICD delivers a shock. For example, you may be told to dial 911 or go to the nearest emergency room in the event of a shock from the ICD. Calming yourself with slow deep breaths can be helpful if you are anxious after a shock.

Ask your doctor when you will be able to return to work. The nature of your job, your overall health, and your progress will determine how soon you may return to work.

After implantation, your ICD will require regular evaluation (called an interrogation) to evaluate its function and battery status, and to check for any significant events stored by the device. Your doctor will tell you when and how this is done.

A home monitor may be provided to you that can communicate with your ICD wirelessly. Information about ICD function can then be related to your doctor over the internet.

Tell your doctor right away if you have any of the following:

• Fever or chills

• Increased pain, redness, swelling, or bleeding or other drainage from the insertion site

• Chest pain or pressure, nausea or vomiting, profuse sweating, dizziness or fainting

• Palpitations

• ICD shock

• If your device generator feels loose or like it is wiggling in the pocket under the skin

Your doctor may give you other instructions after the procedure, depending on your particular situation.

Living with an ICD

Take the following precautions when you have an ICD implanted. Discuss the following in detail with your doctor, or call the company that made your device:

• Always carry an ID card that states you have an ICD. In addition, you may want to wear a medical ID bracelet showing that you have an ICD.

• If you travel by air, inform security screeners that you have an ICD before going through the metal detector. (It may help to say you have a pacemaker – which is true as pacemaker functions are built into ICDs – because security may not know what an ICD is.) In general, airport security detectors are safe for pacemakers and ICDs, but the small amount of metal in the device and leads may trigger the alarm. If you are selected for additional screening, politely remind the screener that the security wand contains a magnet, which may interfere with the programming or function of the ICD (pacemaker) if it is held over the device for more than a few seconds.

• Anti-theft systems or electronic article surveillance (EAS) used in department stores may interact with an ICD. Do not lean on or stand in this equipment. But it is OK to pass quickly through the detection system.

• Avoid large magnetic fields such as power generation sites and industrial sites, such as automobile junkyards that use large magnets.

• If an MRI has been recommended for you, contact your doctor. Some newer ICDs are compatible with MRI scanners with some restrictions.

• Do not use diathermy (the use of heat in physical therapy to treat muscles). Do not use a heating pad directly over your ICD.

• Avoid transcutaneous electrical nerve stimulation (TENS) therapy. Talk to your doctor if you are considering this treatment.

• Turn off large motors, such as cars or boats, when working on them as they may create a magnetic field.

• Avoid high-voltage and radar machinery, such as radio or television transmitters, electric arc welders, high-tension wires, radar installations, or smelting furnaces.

• If you are scheduled for surgery, let the surgeon know well ahead of the operation that you have an ICD. Also, consult with your cardiologist before the procedure to find out if you need any special preparation.

• When involved in a physical, recreational, or sporting activity, protect yourself from trauma to the ICD. A blow to the chest near the ICD can affect its functioning. If you are hit in that area, you may want to see your doctor.

• Cell phones are generally safe to use, but keep them at least 6 inches away from your ICD. Avoid carrying a cell phone in your breast pocket over your ICD.

• Always see your doctor when you feel ill after an activity, or when you have questions about beginning a new activity.

• Always talk to your doctor if you have any questions concerning the use of equipment near your ICD.

Next steps

Before you agree to the test or the procedure make sure you know:

• The name of the test or procedure

• The reason you are having the test or procedure

• What results to expect and what they mean

• The risks and benefits of the test or procedure

• What the possible side effects or complications are

• When and where you are to have the test or procedure

• Who will do the test or procedure and what that person’s qualifications are

• What would happen if you did not have the test or procedure

• Any alternative tests or procedures to think about

• When and how will you get the results

• Who to call after the test or procedure if you have questions or problems

• How much will you have to pay for the test or procedure