ICD or Implantable Cardioverter Defibrillator

Implantable Cardioverter Defibrillators (ICDs) have been very beneficial in averting cases of sudden death in patients with known continuous ventricular tachycardia or fibrillation. Studies show that it plays a vital role in preventing cardiac arrest in high-risk patients who haven't had but are at risk of fatal ventricular arrhythmias.

How it works

ICDs are small devices like pacemakers about the size of a pager and are placed below the collarbone. It is a battery-powered device placed under the skin with thin wires that connect to the heart to track the heart rate. In case an abnormal heart rhythm is detected (the heart is beating chaotically or too fast) the ICD produces an electric shock to re-establish a normal heartbeat. ICDs can also work as pacemakers when the heartbeat is too slow (bradycardia).

The ICD itself consists of a small, thin, battery-driven titanium "generator”. The generator contains a battery, capacitors, a computer, and other sophisticated electronics. The leads transmit the heart's tiny electrical signals (that control the heart rhythm) back to the generator where they are continuously analysed. If a dangerous arrhythmia is detected the ICD immediately treats it by either pacing or shocking the heart through the leads.

ICDs also offer several other sophisticated functions such as storing all detected arrhythmic events and the capacity to perform electrophysiological testing. Stored information helps doctors optimize the ICD for the patient’s needs.

Who should get an ICD?

  • Patients who have had or are at a high risk of having a ventricular tachycardia, fibrillation or sudden cardiac arrest
  • A prior cardiac arrest
  • Patients with rapid heartbeat originating from the lower chambers of the heart (Ventricular tachycardia)
  • Patients with a heartbeat that is too rapid, irregular or chaotic (Ventricular fibrillation)
  • Ejection fractions of less than 35 percent; An ejection fraction (EF) is the proportion, fraction, or percentage of blood pumped by the heart with each beat. A normal heart pumps out a little more than half the heart's volume of blood with each beat, making a normal EF 55 percent or higher
  • Patients at a high risk for sudden cardiac death (SCD) because of an inherited heart abnormality

Living with an ICD

Most patients can continue a near normal lifestyle. But it is best to consult a doctor on what activities one can and cannot do when implanted with an ICD. Recipients need to be aware about the types of machines or equipment they should avoid. It is important to be aware of one’s surroundings and the devices since devices with strong magnetic fields can potentially disrupt its functioning.


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