What is an Automatic Implantable Cardioverter Defibrillator?

The automatic implantable cardioverter defibrillator, or AICD, is an electrical device used to regulate the heart rhythm. It is also known more simply as an implantable cardioverter defibrillator, or ICD. As well as having the ability to act like an ordinary pacemaker, using electrical impulses to correct an irregular heartbeat, the automatic implantable cardioverter defibrillator can apply electric shocks to prevent a heart attack. The device is implanted under the skin of the chest, with a wire which leads through a vein into the heart's right lower chamber, or right ventricle.

Automatic implantable cardioverter defibrillators are currently used to treat conditions which were formerly managed using drugs. These include the disorder called ventricular tachycardia, where the lower chambers of the heart, or ventricles, beat too quickly. A prolonged episode of ventricular tachycardia can worsen into what is known as ventricular fibrillation, when the muscle fibers in the ventricles beat completely at random, the heart can no longer function, and there is a risk of death. An automatic implantable cardioverter defibrillator may be recommended for someone who has already suffered from a cardiac arrest caused by ventricular tachycardia or ventricular fibrillation.

Once in place, the device is able to pace the heart when ventricular tachycardia occurs, or, conversely, when the heartbeat becomes too slow. Bursts of electrical activity are delivered to the heart by way of the wire lead inside the right ventricle, helping to reinstate a normal rhythm. If tachycardia continues, a stronger jolt of electricity known as a cardioversion shock is used to stop the heart from beating so rapidly. Should fibrillation occur, the device acts as a defibrillator, and a powerful shock is sent to the heart muscle to restore a regular heart rhythm.

In most cases an automatic implantable cardioverter defibrillator is effective, reducing a person's risk of death due to abnormal heartbeat conditions. Sometimes patients need to take medication in addition to having the AICD, and occasionally there may be problems, such as the device delivering shocks when they are not required. A number of patients develop psychological problems associated with the automatic implantable cardioverter defibrillator, becoming apprehensive and anxious about the possibility of a shock occurring.

Shocks feel quite violent if they occur when the patient is conscious, and the AICD may come to be associated with feelings of loss of control and helplessness, leading to depression. The amount of mental distress caused by having an automatic implantable cardioverter defibrillator seems to be related to the number of times the device actually fires. Psychological treatment such as cognitive behavioral therapy may be beneficial for those who experience anxiety and depression. Support groups for patients and their families have also proved helpful.