Internal Cardiac Defibrillator (ICD)

An automatic implantable cardioverter defibrillator (ICD or AICD) is a device that monitors a person’s heart rate. The device can speed up or slow down your heart, depending upon your heart rate. The ICD gives your heart a shock to make the heart start beating normally again if you start having life-threatening arrhythmias or an abnormally high heart rate. An ICD can also make your heart beat faster if your heart is not beating fast enough.

ICDs have two parts: electrodes (thin flexible wires) and a generator. The electrodes or “leads” sense or watch the heart’s electrical activity. The generator is the battery power source and the “brains” of the ICD. It is a small metal can about the size of a deck of cards. The generator stores information about any arrhythmias you have. The generator also keeps track of how often it needs to give your heart a shock.

Who needs an ICD?

You may need an ICD if you have:

• At least one episode of ventricular tachycardia (VT) or ventricular fibrillation (Vfib)
• Previous cardiac arrest or abnormal heart rhythm that has caused you to pass out
• A fast heart rhythm that keeps returning and could cause death
• A fast heart rhythm that cannot be cured by surgery
• A fast heart rhythm that cannot be controlled with medications
• Severe side effects from medications

How does ICD implantation work?

An electrophysiology test can help your doctor decide whether to use an ICD or whether to use drugs for treatment. ICD implantation is minimally invasive. Your doctor will make an incision in your upper chest below the collarbone and insert a wire through a vein into your heart. Sometimes more than one wire is used. The doctor will create a “pocket” in your chest, where the ICD is inserted. The ICD is connected to the wires. The doctor will test the ICD by creating an arrhythmia and then observing whether the ICD delivers the required therapy.

Later that day, or the next day, your ICD system will be checked and tested again. You will receive sedation. The doctor will provoke an arrhythmia to see if the device works. The ICD will deliver a shock (defibrillation). The staff will fine-tune the equipment. Hospital stays are rarely longer than 3 or 4 days and you can quickly return to your former levels of activity.

Do ICD batteries wear out?

Just like a battery you use with your electronic equipment, the battery can wear down over time. How long the ICD pulse generator will last depends on settings programmed into the system and how often it must deliver shocks to your heart.