Implantable defibrillators are used to treat dangerous, rapid heartbeats (ventricular tachycardia or ventricular fibrillation).

Tachycardia refers to a fast heart rate. Fibrillation refers to fast, uncoordinated beats, a ‘quivering heart’.

Implantable defibrillators are slightly larger than pacemakers and have leads that are directly connected to the heart to continuously monitor your heart rhythm and deliver precisely calibrated electrical shocks when needed to control abnormal, rapid heartbeats. The devices can also stop other types of irregular heart rhythms (arrhythmias).

What is an ICD?

• The ICD is a small, battery-driven, self-contained device that's implanted under your skin, usually near your left collarbone. One or two thin wires (leads) run from the ICD through your veins to the chambers of your heart.
• The ICD continuously monitors your heart rhythm and treats rapid heartbeats with electrical therapy.
• When you experience ventricular tachycardia, external defibrillators can shock your heart back into a normal rhythm. Such defibrillators are available at hospitals, and ambulances and police cars often carry portable versions. Not everyone is near a hospital or an emergency worker, however, when a rapid heartbeat occurs. The time between the onset of ventricular tachycardia and loss of consciousness or death may not be long, and the sooner treatment can be administered, the sooner your heart may return to a normal rhythm. According to the American Heart Association, death can occur just 4 to 6 minutes after a cardiac arrest.
• The ICD is a readily available defibrillator that can administer electrical therapy almost immediately when needed. If you are at high risk of dangerous heart rhythms, it can be lifesaving.

How does an ICD work?

• Each ICD is individually programmed. You may undergo a series of electrophysiology studies before, during and after ICD surgery to help your doctor program specific, individualized instructions into the device. Your doctor programs the ICD to include one or all of the following functions:
• Anti-tachycardia Pacing (ATP) – When the heart beats too fast, a series of small electrical impulses are delivered to the heart muscle to restore a normal heart rate and rhythm.
• Cardioversion – A low energy shock is delivered at the same time as your heartbeat to restore a normal heart rhythm.
• Defibrillation – When the heart is beating dangerously fast, a high-energy shock is delivered to the heart muscle to restore a normal rhythm
• Bradycardia Pacing – When the heart beats too slow, small electrical impulses are sent to stimulate the heart muscle to maintain a suitable heart rate.
• ICDs also function as pacemakers. This means that in addition to treating fast heartbeats, they can also prevent slow ones.
• Some ICDs are also capable of biventricular pacing. In biventricular pacing, two pacing wires are placed in the bottom chamber of your heart instead of one, which is more common. For some people with weakened heart muscle, this type of pacing can strengthen their heartbeat and help control symptoms of heart failure.

Single Chamber ICD
A lead is attached in the right ventricle. If needed, energy is delivered to the ventricle to help it contract normally.

Dual Chamber ICD
Leads are attached in the right atrium and the right ventricle. Energy is delivered first to the right atrium and then to the right ventricle, helping your heart to beat in a normal sequence.

Biventricular ICD
Leads are attached in the right atrium, the right ventricle, and the left ventricle. This technique helps the heart beat in a more balanced way and is specifically used for patients with heart failure.

Who needs an ICD?

• People who have had an episode of sudden cardiac death or ventricular fibrillation
• People who have had a heart attack and are at high risk for sudden cardiac death
• People who have hypertrophic cardiomyopathy and are at high risk
• People with at least one episode of ventricular tachycardia

What Can I Expect?

• Your doctor may ask you to stop certain medications one to five days before your test (such as aspirin products). Ask your doctor what medications you are allowed to take. If you are diabetic, ask your doctor how you should adjust your diabetic medications.
• Do not eat or drink anything after midnight the evening before your test. If you must take medications, drink only with a sip of water
• When you come to the hospital, wear comfortable clothes. You will change into a hospital gown for the procedure. Leave all jewelry or valuables at home.
• You will lie on a bed and the nurse will start an intravenous line (IV) into your arm or hand. This is so you may receive medications and fluids during the procedure. You will be given an antibiotic to prevent infection and a medication through your IV to relax you and make you drowsy, but it will not put you to sleep.
• The nurse will connect you to several monitors. The monitors allow the doctor and nurse to check your heart rhythm, blood pressure and other measurements during the pacemaker implant.
• Your left or right side of your body, from your neck to your groin will be shaved and cleansed with a special soap. Sterile drapes are used to cover you from your neck to your feet. A strap will be placed across your waist and arms to prevent your hands from coming in contact with the sterile field.

 The ICD may be implanted in two ways:

Endocardial (transvenous) Approach (most common)

• A small incision is made under the collar bone
• Lead is placed into a vein and guided inside your heart chamber
• Generator is placed under skin in upper chest and attached to the lead(s)

Epicardial Approach (outside your heart)

On a rare occassion, it may be necessary for your doctor to implant your ICD by epicardial approach (outside your heart).

• This requires open heart surgery. Instead of placing the lead through a vein and guiding it to the heart, it is sewn onto the heart. Your doctor will decide if this approach is necessary for you.
• The ICD implant takes about one to three hours to perform.

After the Procedure

Hospital Stay
You will be admitted to the hospital overnight. The nurses will monitor your heart rate and rhythm. The length of your hospital stay depends on the type of ICD procedure you had. The morning after your implant, you will have an EKG, blood tests and a chest x-ray to ensure the leads and/or patches and ICD is in the proper position.
Wound Care: Keep your wound clean and dry. After five days, you may take a shower. Look at your wound every day to make sure it is healing.

Call your doctor if you notice:

• Redness
• Swelling
• Drainage
• Fever
• Chills

You will have a slight bulge under the skin where the generator is located. It will not be noticeable under clothes. If the ICD implant is in your abdomen, avoid wearing tight fitting clothing or tight belts so your wounds will not be irritated.

ICD Identification
You will be given information about:

• The type of ICD and leads you have
• The date of implant
• The doctor who implanted them
• In about three months you will receive a permanent card from the company. It is important that you carry this card at all times in case you need medical attention.

Activity
You may move your arm normally. You can do most activities when you return home.

• Avoid lifting objects that weigh more than 20 pounds or pushing or pulling heavy objects.
• If you had heart surgery, it may take longer to get back to some activities.
• Your doctor or nurse will discuss specific activities with you before you leave the hospital

Electrical Interference
Most electrical devices, such as microwave ovens, do not interfere with ICD function. You need to avoid strong electric or magnetic fields such as some industrial equipment, high output ham radios, high intensity radiowaves (found near large electrical generators, power plants or radiofrequency transmission towers), and arc or resistance welders.

Stay at arm's length away from less powerful electric or magnetic fields such as large magnets, stereo speakers, airport security wands, antennas used in ham or CB radios.

Cell phones should be kept at least 6 inches from your ICD and not on the same side as your ICD.
 
Do not undergo any tests that require magnetic resonance imaging (MRI). You may have CT ("CAT") scans done if necessary. If you have concerns about your job or activities, ask your doctor.

ICD Therapy:
You may or may not be aware of when your ICD detects and corrects your heart rhythm. Often it depends on the type of therapy you receive:

• Pacing - you may or may not feel the impulses - usually they are not detectable
• Cardioversion - shock feels like a thump on the chest; discomfort does not linger
• Defibrillation - you may be unconscious (passed out) and not feel the shock. If you are awake, the shock feels like a kick in the chest; felt for only a moment.

If you receive a shock:

• Stay calm. Sit or lie down.
• Ask someone to stay with you.
• If you do not feel well after the shock, call your doctor or an ambulance (Dial 911 in most areas).
• If you feel fine after the shock, you do not need to seek immediate medical attention. Call your doctor within 24 hours.
• If someone is touching you when the ICD fires, they may feel a tingling feeling. This is not harmful to them.

Follow-Up
Regular follow-up is important after an ICD implant. These visits typically occur every 3 to 6 months. During ICD checks, the doctor will determine if the ICD had detected or treated any abnormal heart rhythms and will check the ICD battery. These visits are very important. You will also need to see a cardiologist at least once a year.