An ICD is designed to monitor your heart rhythm. If your heart is beating too fast or irregularly, the device will first send small painless electrical signals to correct your heart rate. If the fast heart rate continues, the defibrillator will deliver a shock to restore your heart to a normal rate.

The implantable defibrillator may 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 treatments for your specific heart condition.