Difference between an ICD and a Pacemaker

December 7, 2016 by Editorial Team

Individuals who have arrhythmia suffer from problems with the electrical system of their heart. This causes the heart to beat quicker than normal or in an irregular pattern. In medical cases like these, devices such as pacemakers and ICDs can help save lives. Is a pacemaker different from an ICD? Let’s find out.


An implantable cardioverter defibrillator includes a microcomputer and a lithium ion battery in a sealed case

An ICD, or implantable cardioverter defibrillator, is a device that continuously monitors heart rhythms to control arrhythmia. It is surgically implanted either in the abdomen or in the chest. Modern ICDs can function as both a defibrillator and pacemaker.

The ICD sends a small electric charge to the heart when if detects abnormal heart rhythms, particularly ones that can cause a sudden cardiac arrest. If the small electric pulses fail to restore the heart back to its normal rhythm, the ICD then sends high-energy pulses that last a millisecond. The second electric shock can be painful. This life-saving process is called defibrillation.

An ICD is equipped with electrodes wired to the heart chambers. In addition to stopping arrhythmias, an ICD also monitors and records the heart’s electrical patterns for future medical reference or treatment.

A MedTronic Enrhythm Pacing System: a popular pacemaker that can correct irregular heartbeats

A pacemaker is small device that doctors use to detect and control arrhythmias. It is implanted in the chest and can only send faint electrical pulses to correct less critical heart rhythms, particularly those that happen in the upper chambers of the heart.

Pacemakers monitor and detect slow, fast, and irregular heartbeat that can cause the heart to fail to pump enough blood in the body. They can relieve symptoms such as fainting and fatigue. They can also improve the quality life of a person who suffers from abnormal heart rhythms.


While both life-saving devices can treat cases of arrhythmia at the first sign of trouble, they slightly differ on how they operate to treat heart ailments.

ICDs and pacemakers both monitor and detect slow, fast, and irregular heartbeats caused by arrhythmia. An ICD can send either a low-powered or a high-powered electrical impulse to set the heart back to its normal beating pattern. However, a pacemaker can only give out low energy impulses to correct less serious cases of arrhythmia that commonly strikes the upper chambers of the heart. An ICD can help treat serious cases of arrhythmia.

Comparison Chart

Sends out high and low energy impulsesCan only send low energy impulses
Can help prevent serious cardiac arrestMaintains correct heart rate


Here’s a YouTube video for more about these life-saving devices.