What is in an Implantable Cardiac Defibrillator (ICD), and how does it work? Please elaborate.
An implantable cardiac defibrillator is a electronic medical device implanted surgically through the skin (percutaneously) in patients who have a medical history of lethal arrythmias (dysrthymia ). An arrhythmia or dysrythmia is a disturbance in the cardiac conduction system which leads to many different types of irregular heart rhythm's. These irregular rhythm's cause a multitude of problems including low blood pressure (hypotension), asystole(no heart beat), and others. The defibrillator senses and reads the patient's cardiac rhythm and when it detects a lethal or fatal rhythm it defibrillates or "shocks" the heart in an effort to correct that rhythm and return the myocardium back to a sustainable rhythm.
ICD's differ from pacemakers in so far as cardiac pacemakers do not shock the heart, they regulate the underlying rythm. A patient who needs a pacemaker does not necessarily need a defibrillator and vice versa.
An Implantable Cardioverter (Cardiac) Defibrillator is used in patients who are at risk for recurrent, sustained ventricular tachycardia or fibrillation. It is a device that is attached to leads that are attached to the inside of the heart or on the surface of the heart. A pulse generator is implanted beneath the skin in the chest or abdomen.
An ICD is a very sensitive device that monitors cardiac rhythm and sends electrical shocks to the heart. The reason it does this is to pace the heart when needed and in doing so it restores the hearts natural rhythm.
Many lives have been saved because of this device.