Implantable Cardioverter Defibrillators
The implantable cardioverter defibrillator (ICD) system includes devices implanted in your body:
- The ICD pulse generator is a battery-powered, computer-like device. It is about the size of a Mason jar lid.
- One or two lead wires will connect the heart muscle to the pulse generator.
ICDs continuously monitor the heart rhythm, in one or both chambers. It is always on call, continuously monitoring your heart 24 hours a day. If your ICD detects a rhythm problem, it sends out electrical signals to correct it.
- The ICD can treat abnormally fast ventricular heart rhythms by delivering tiny amounts of electrical energy (anti-tachycardia pacing) to the heart. This energy slows the heart down to a more normal rhythm.
- If the ICD senses a heart rate that is dangerously fast, it delivers a shock to the heart. This shock (defibrillation) stops the abnormal rhythm. Without this life-saving therapy, the dangerously rapid rhythm could lead to a sudden cardiac arrest. This could lead to a sudden cardiac death within minutes.
ICD devices are recommended for patients at risk of sudden cardiac arrest (SCA). SCA can strike without warning. Often people who experienced it felt fine moments before.
- Coronary artery disease – About 90% of adult victims of SCA have plaque in two or more major heart arteries (coronary arteries).¹
- Heart Attack – About 75% of sudden cardiac arrest victims have scarring in their heart muscle from a prior heart attack.¹
- Other heart problems – When SCA occurs in young adults other rare heart conditions are likely the cause, such as hypertrophic cardiomyopathy.¹
How to Prepare
Your healthcare provider will give you specific instructions about preparing for your implant procedure. Follow the instructions carefully.
Your healthcare provider determines whether you should continue or stop certain medications, if you should avoid eating or drinking in the hours before surgery and what to expect when you check into the hospital.
It is important for you to tell your doctor if you cannot take aspirin or have a history of bleeding problems. Your doctor also needs to know if you are taking any other medications, have drug allergies, or are allergic to any metals or plastics.
What to Expect
The procedure to implant an ICD system in your body usually takes about an hour. During the surgery, you will be attached to monitors for your heart rate and blood pressure.
An intravenous (IV) line will be started in your arm and you will be given medicine to help you relax and get sleepy. This is called conscious sedation, which means you remain aware of your surroundings and are able to talk to the staff, but you should not feel any pain.
Implanting an ICD System - Watch the Video [00:20]
Placing the pulse generator and leads
Your doctor will determine the best way to implant your pulse generator. Your age and the size of your heart will be considered. Your doctor will also consider whether you have ever had chest surgery. Your activities and lifestyle may suggest where the ICD is implanted.
Your ICD device will likely be implanted just under the skin beneath the shoulder. Coated wires called leads carry the electrical signals between the device and the heart. The ICD system may also be implanted in the abdomen.
- A “single-chamber ICD” has one lead in the ventricle. It is looking for ventricular fibrillation.
- A “dual-chamber ICD” has a lead in both in the atrium and ventricle. It is looking for arrhythmias that may cause a fast ventricular heart rate.
Your healthcare provider will clean and numb the site where the ICD will be implanted. Then, the doctor will make a small pocket under the skin for the pulse generator and will place the lead or leads.
For most patients, the leads are placed inside the heart. The doctor opens a vein, usually through a small cut near your collarbone. The doctor can then thread the lead through the vein and position it inside your heart chamber. The tip of the lead rests against the inner heart wall.
If your heart condition requires pacing in two-chambers, another lead is positioned in the upper right chamber (atrium) of your heart. This dual-chamber lead system allows the pulse generator to watch and treat the areas of heart that your doctor has determined need monitoring.
After the leads are in position, they are tested to make sure they sense your heart signals clearly. The leads are then stitched to nearby tissue so that they won't move. Finally, the leads are connected to the pulse generator.
Once the ICD system is in place, it is tested to make sure it is working correctly. You may feel your heart beating faster during these tests.
Testing the System
During the operation, the whole ICD system will be tested to make sure it is working properly. For this test, your doctor will start an arrhythmia in your heart. The ICD system will sense the rhythm and give the programmed treatment. For this test, you will be given medicine to go to sleep.
These steps are taken to insure that the ICD system can sense the life-threatening rhythms and deliver the appropriate energy to treat them.
When the testing is finished, your doctor will close the pocket that holds the pulse generator. As you recover from the surgery, you may experience some discomfort from the incision.
What Happens Next
The procedure to implant the ICD system usually takes about an hour. In most hospitals the doctor talks to the family right after the implant—usually to answer questions and to report how the procedure went. The doctor may also see you in the recovery room, although you may be too groggy to talk very long. You might even forget talking to the doctor.
It's a good idea for a couple of family members or friends to be at the hospital. They can talk to the healthcare provider after the procedure. They can then fill you in on the details when you are more alert and help you gather questions for the next time the healthcare provider sees you.
Testing your ICD
Before you leave the hospital, your doctor may test the ICD again.
Your experience of ICD therapy will be as unique as you are. People with abnormal heart rhythms may experience unusual sensations during their arrhythmias, but not everyone feels their arrhythmias.
Your ICD system is designed to deliver treatment based on what it senses even if you don't feel any symptoms. However, you may feel sensations during therapy delivery. These feelings have been described in a variety of ways.
- Anti-tachycardia pacing – You may not feel this fast type of pacing therapy when it is delivered to your heart. You may have a feeling of fluttering in your chest. Most patients who receive ATP therapy say it is painless.
- Cardioversion – These low-energy shocks are stronger than pacing pulses. Many patients say cardioversion is mildly uncomfortable. It feels like a thump on the chest.
- Defibrillation – Many patients faint or become unconscious shortly after a very fast VT or VF rhythm starts. As a result, they do not feel these high-energy shocks. Of those patients who are conscious, some describe the shock like a "kick in the chest." Usually, the shock comes suddenly. The sensation lasts for only a second. While many find the shock reassuring, other patients may feel anxious for a short time after shock therapy is delivered.
- Bradycardia pacing – These pacing pulses are very low energy and, typically, patients do not feel them.
If any of the following are experienced, it is very important to call the healthcare provider.
- Bleeding at the insertion site
- Increased pain
- Any complaint of chest pain
- Shortness of breath
- Feeling cold, have swelling, or numbness on the arm or leg of the insertion site
- The bruising or lump at the insertion site gets larger
- Fever over 100° F
- Return of arrhythmia symptoms
Be sure to talk with your healthcare provider so that you thoroughly understand all of the risks and benefits associated with the implantation of this system. As you recover from your implant surgery, you will find that your device may allow you to return to your normal activities.