Comprehensive Cardiovascular Care Group:Implantable Cardioverter Defibrillators

In 1983 the first defibrillator is implanted.

Since 1983, we have performed more than 2000 ICD procedures-the largest number in the state of Wisconsin and one of the largest numbers in the United States. We also have the best operative safety record for ICD implants in the nation.

About Implantable Cardioverter Defibrillators (ICD's)

If medications are not considered the best option or have failed in controlling ventricular tachycardia or ventricular fibrillation, an ICD will be offered - with frequently both conventional and newer devices available. An ICD, which can now be implanted without opening the chest, monitors the heart�s rhythm and if an abnormal rapid rhythm is detected, it sends a varying form of energy back to the heart to restore a normal heartbeat. The device�s generator (about half the size of a deck of cards) is implanted in the chest-pectoral region, like a pacemaker. One or more long, thin wires, called "leads" run from the device to the heart. Additional leads may be placed in or outside the heart, if indicated. These leads then feed the heart�s electrical impulses to the generator for monitoring. When an abnormal signal is received, the preprogrammed device sends up to three different kinds of responses to the heart to rectify the irregularity. Depending on the abnormal rhythm, the ICD may send a series of rapid electrical impulses (probably undetectable to the wearer) called pacing; it may send a low-energy shock (similar to a small thump) called cardioversion; or it may send a high-energy shock (feels like a kick or a blow) called defibrillation.

Living With Your Implantable Defibrillator

The Defibrillator
An implantable defibrillator has two main parts:

A pulse generator, placed in the upper pectoral region which holds the "brains" and battery of the device.

Wires (called "leads") which connect to the heart. These wires can sense the heart�s rate and can shock the heart if needed.

How it is Implanted
Leads for the defibrillator are usually implanted by threading them through a large vein that goes to the heart. This is called transvenous placement. A small incision is made over a vein in the upper chest. One or two leads are inserted through the vein to the heart. A small patch may also be placed under the skin on the left side of the chest. The ends of the leads and patch are tunneled under the skin and attached to the generator, which is usually placed in the left pectoral region (near your left shoulder, above your left breast). The term "pectoral implant" refers to the fact that the generator is now located near the pectoral muscle in the upper chest.

On rare occasions, the defibrillator leads can be implanted directly over the heart during surgery. Your doctor will advise you if this is the way your leads need to be implanted.

How Your Device Works

During your Electrophysiology Study, or on an ECG or other type of rhythm strip, your doctor has discovered which type of arrhythmia you have and at what heart rate your heart goes into the arrhythmia. When your device is implanted, it will be programmed to detect this rate or problem. When it does, it will try to stop the rhythm in one of three ways. Your electrophysiologist will choose which methods are best for your rhythm problem.

The three ways are:

Pacing (called antitachycardia or fast pacing) � The device may send small, rapid electrical impulses to your heart. These impulses will try to stop your abnormal rhythm and let the normal heart rhythm return. You will probably not feel these pacing impulses.

Cardioversion � The device may send a low-energy shock through the two patches attached to your heart. One or more of these shocks can be sent to convert your fast heart rhythm to a more normal rhythm. You will be aware of the shock even though it is at a low energy level. It may feel like a small jol