icd device on blue background

Implantable Cardioverter Defibrillator (ICD) For Tachycardia



What is an ICD?

When people refer to an implantable cardioverter defibrillator (ICD), they are actually discussing the system - the defibrillator and the leads.

  • A pulse generator (defibrillator) works like a small computer & continuously monitors the heart and automatically delivers electrical pulses or shocks to correct fast heart rhythms. It is a small device about the size of a matchbox and is usually inserted just under your collarbone.
  • Leads are thin soft insulated wires about the size of a spaghetti noodle. They are placed in your heart through a vein and are connected to the defibrillator. Leads carry the electrical impulse from the defibrillator to your heart and relay information about the heart’s natural activity back to the defibrillator.

Watch Bernard Gallacher's story

Even professional golf players can experience a cardiac arrest and need an implantable defibrillator. Hear from Bernard Gallacher and his physician.


An implantable cardioverter defibrillator is designed to monitor your heart rhythm 24 hours a day. If your heart is beating too fast or irregularly, the device will first send small painless electrical signals to correct your heart rate (this is called anti-tachycardia pacing or ATP ). If the fast heart rate (tachycardia) continues, the defibrillator will deliver an electric shock to restore your heart to a normal rate. This electric shock is synchronised with the heart’s rhythm as far as possible and is then referred to as cardioversion. If the electric shock cannot be synchronised with the heart’s rhythm, e.g. during ventricular fibrillation, it is referred to as defibrillation.

The implantable cardioverter defibrillator can also treat slow heart rhythms by sending electrical pulses to the heart to correct it.

Your doctor will program the ICD to deliver the most effective therapies for your specific heart condition.

The ICD battery

The energy needed for the ICD to work comes from a special battery. How long your battery lasts depends on several factors. Some of these factors include the type of ICD you have, the nature of your heart condition, and how often your ICD provides therapy to your heart.

It could last up to 13 years1. Because your ICD operates using a battery sealed inside the device, the entire device (pulse generator) will need to be replaced when battery power falls to a low level. The leads only need to be changed in exceptional cases.

Watch Ciara's ICD Story

Ciara tells us how getting an ICD not only improved her symptoms but also saved her life.

What do Medtronic Device Tones Sound Like?

Did you know that your heart device can emit tones? Watch the video to learn more.

Watch the animation and download the infographic to learn about heart failure

Information on this site should not be used as a substitute for talking with your doctor. Always talk with your doctor about diagnosis and treatment information.


Medtronic Cobalt™ XT VR MRI SureScan™ Model DVPC3D4 device manual (example).



Subject to local availability

Free-of-charge number

Ability to leave voicemail outside of office hours