An implantable cardio defibrillator, or ICD, is a small electrical impulse generator. The ICD is traditionally used in patients who are at risk for serious cardiac attacks which can lead to sudden cardiac death. These attacks, ventricular fibrillation and ventricular tachycardia, are defined as having an uncoordinated beating rhythm or a rapid heart rate, respectively. If an attack is sensed by the ICD, an electrical shock is delivered to the heart to restore normal rhythm. Newer devices are relatively small, approximately the size of the palm of your hand, and can be implanted via blood vessels, which eliminates the need for open-heart surgery.
Single-Chamber ICD
The heart is comprised of four chambers: the right and left atrium and the right and left ventricle. A single-chamber ICD is implanted either on the heart's surface or next to the heart. Its wires are then attached to the right ventricle. When needed, an electrical shock is delivered to the right ventricle to help it regain normal rhythm.
Dual-Chamber ICD
A dual chamber ICD is attached to two chambers of the heart: the right atrium and the right ventricle. When the dual chamber ICD senses an attack, an electrical shock is sent to the right atrium first, followed by a shock to the right ventricle. This series of shocks helps the heart regain a normal rhythm.
Biventricular ICD
A biventricular ICD is specifically used for patients with heart failure. Heart failure is a disorder that progresses over time, causing a weakening of the cardiovascular system which ultimately leads the heart to inefficiently pump blood to the body. The wires of a biventricular ICD are attached to both the right and left ventricle and the right atrium. It is able to detect when the heart is beating inefficiently and will deliver a shock to the heart to regain normal rhythm.
