What is Ventricular Fibrillation?

When a ventricular arrhythmia (irregular heartbeat) becomes very fast and irregular, it's called ventricular fibrillation. The heart just quivers, and no blood is pumped to the brain or the body. A person with ventricular fibrillation usually passes out very quickly. Unless treatment is given in 5-10 minutes, ventricular fibrillation causes death.

In people who don't have an ICD, ventricular fibrillation is treated with an external defibrillator. Paddles are put on the outside of the chest and an electrical shock is given through the paddles. This shock goes through the heart and stops the irregular beat. The heart then goes back to a more regular rhythm.

Unfortunately, ventricular fibrillation can occur without warning-often treatment can't be given in time. An ICD may be recommended for you because your doctor thinks you're at high risk for ventricular fibrillation. The ICD can quickly recognize and stop ventricular fibrillation.

How Does an ICD Work?

The ICD constantly watches your heart rhythm. If it sees that your heart is beating fast, it delivers the treatment programmed by your doctor. The ICD can do several things:

Pacing: If you have ventricular tachycardia that isn't too fast, the ICD can deliver several pacing signals in a row. When the signals stop, the heart may go back to a normal rhythm.

Cardioversion: If the pacing doesn't work, cardioversion can be used. In cardioversion, a mild shock is sent to the heart to stop the fast heartbeat.

Defibrillation: If ventricular fibrillation is detected, a stronger shock is sent. This stronger shock can stop the fast rhythm and help the heartbeat go back to normal.

Pacemaker: The ICD can also see when your heart beats too slowly. It can act like a pacemaker and bring your heart rate back up to normal.

How is an ICD Implanted?

The pulse generator may be implanted under you collarbone, or in your abdomen. The doctor will make a pocket under your skin or in a muscle to put the generator in. One end of the lead wire is put into a vein that goes to your heart. The wire is moved through the vein until it reaches the heart. The other end of the wire is attached to the pulse generator. Once implantation is complete, your doctor will program the ICD to treat your specific heart rhythm problem.