An implantable cardioverter defibrillator (ICD) is a device that monitors heart rhythms, and delivers shocks if dangerous rhythms are detected.

Many ICDs record the heart’s electrical patterns whenever an abnormal heart beat occurs. Doctors can review this record during regular check-ups to help plan future treatment options.

When is it used?
ICDs are used to treat patients whose lower heart chambers (ventricles) beat too quickly (tachycardia) or quiver ineffectively (fibrillation). They are also used in patients who are at risk of these conditions due to previous cardiac arrest, heart failure, or ineffective drug therapy for abnormal heart rhythms.

How does it work?
Like a pacemaker, an ICD consists of a battery and electrical circuitry (pulse generator) connected to one or more insulated wires. The pulse generator and batteries are sealed together and implanted under the skin, usually near the shoulder. The wires are threaded through blood vessels from the ICD to the heart muscle.

The ICD continuously checks the heart rate. When it detects a too-rapid or irregular heartbeat, it delivers a shock that resets the heart to a more normal rate and electrical pattern (cardioversion).

Stopping the potentially fatal fibrillation is called defibrillation.

What will it accomplish?
ICDs protect against sudden cardiac death from ventricular tachycardia and ventricular fibrillation.

What are the risks?
Potential risks from the surgical procedure include infection, bleeding, and bruising. Other rare complications include stroke, heart attack, blood clots, or perforation of a major vessel, a lung, or the heart muscle.

Your doctor will tell you about additional risks from ICDs.

Electromagnetic Interference
Some devices in your surroundings may interfere with your ICD. You may need to avoid certain types of security devices. Always carry your wallet ID card with you.

Household devices and appliances may affect your ICD. Ask your doctor which devices to avoid.
Some medical equipment can damage your ICD. If you are visiting your doctor or dentist, tell him or her that you have an ICD BEFORE they do any testing or treatment.
Some security devices may affect your ICD. A general rule of thumb is “Don’t lean, don’t linger” when moving through these devices.
Welders and electric generators may affect your ICD.

When should it not be used?
ICDs should not be used in patients whose heart conditions are reversible or temporary. They should not be used in patients who will not benefit from the devices, or who are sensitive (allergic) to the exposed components.