What is the difference between a pacemaker and an implantable defibrillator?

In electrophysiology we treat heart rhythm problems, such as when the heart becomes irregular, when it gets fast or when it gets slow. There are various ways to treat heart rhythm problems. If the heart rhythm gets very slow and it is not treatable with changes in medications then a pacemaker is needed.

What a pacemaker does is keep the heart beating at the proper rate and from beating too slow. You can adjust the pacemaker so that it can be suitable for either the top or bottom heart chambers or both, depending on what type of pacemaker it is and the needs of the patient. It also will only work if it is needed, it doesn't work all the time.

An implanted defibrillator is a bigger device. It is there to prevent death from a cardiac arrest. The device shocks the heart if it needs to be shocked, because of a life-threatening rhythm disturbance from the lower chambers of the heart. It can correct this rhythm. Because it has a pacemaker built into it, a defibrillator also has the capability of stimulating the heart like a pacemaker, to help stop fast rhythms, at times, and to prevent the heart from getting too slow.

Images/Video made available by Boston Scientific