What is an Implantable Cardioverter Defibrillator (ICD)?

Peter Dazeley/The Image Bank/Getty Images
Peter Dazeley/The Image Bank/Getty Images

ICD stands for Implantable Cardioverter Defibrillator. It is made up of a small, slim, box shaped device which contains a battery and electronic circuits. The device is connected to your heart by wires known as leads. The leads are passed along a blood vessel to your heart and the ICD box is usually implanted under the skin in your upper chest, near your collar bone. The ICD can recognise and monitor your heart rhythm and can give you some treatments if needed. It also stores information about your heart rate and rhythm which can be accessed when you come to the clinic for follow-up

What is Cardiac Resynchronisation Therapy?

Cardiac Resynchronisation Therapy (CRT) devices are used to help to treat heart failure and can be either a permanent pacemaker or an ICD. They work by making the heart chambers pump at the same time (synchronously) and improve the overall function of the heart so that you feel lees breathless and have more energy.

What can the ICD do?

Most modern ICDs have three main functions; however you may not need to have all of them. Your Cardiologist will select what settings are best for your condition.

  • If your heart rhythm is too slow, the device can give your heart extra beats by working as a normal pacemaker. This is called anti-bradycardia pacing.
  • If your heart beats too fast, the ICD can give you a burst of extra beats at an even faster rate which will normally return your heart back to a normal rhythm. This is called anti-tachycardia pacing (or ATP).
  • If the anti-tachycardia pacing doesn’t bring your heart back to a normal rhythm, or if the ICD senses a faster rhythm called ventricular fibrillation, the ICD can then give a higher energy shock. This is called defibrillation