Pacemaker Your doctor may have told you that you need a pacemaker. Now, you probably have questions and concerns about the pacemaker, how it is inserted into your body, and how to care for it. This page can help answer many of your questions. What is a pacemaker? A pacemaker is a small, lightweight electronic device that is prescribed for people whose hearts are beating too slowly. It is implanted (inserted) into the body, usually in the upper chest, near the shoulder. The pacemaker keeps track of the heart's electrical activity. If it senses that the heart is beating too slowly or is pausing too long between beats, the pacemaker delivers electrical impulses that pace (stimulate) the heart and keeps it beating at the proper speed. Why is the pacemaker important? If your heart rhythm (the speed and pattern of your heartbeat) is too slow, this may cause symptoms such as lightheadedness, fainting spells, and tiredness. A pacemaker gives your heart the extra help it needs to relieve your symptoms and help you feel better. Also, having a pacemaker can give you more freedom to do the activities you enjoy. When is a pacemaker needed? Sometimes, the heart's electrical system does not work properly. This may cause abnormal heart rhythms, called arrhythmias. During an arrhythmia, the heart may beat too slowly, too fast, or irregularly. A pacemaker is most commonly used to treat heart rhythms that are too slow (bradycardias). In some cases, it may be used to treat other conditions, such as syncope (passing out). When can a pacemaker help? The decision on whether you need a pacemaker will depend on the type of arrhythmia you have, how severe your symptoms are, and whether you have other problems with your heart. Your doctor may recommend a pacemaker if you have one or more the following conditions: bradycardia with significant symptoms, such as dizziness, fainting spells, tiredness, confusion, or shortness of breath bradycardia with a very slow heart rate or long pauses between beats, even without symptoms arrhythmias where the heart alternates between beating too fast and too slowly arrhythmias and other medical conditions that require medications that cause bradycardia recurring syncope that is caused, at least in part, by significant slowing of the heartbeat severe bradycardia caused by heart surgery or catheter ablation Your doctor will decide if you need a pacemaker, and if so, he or she will explain the reasons to you. How does a pacemaker work? A pacemaker has two main functions. It keeps track of the heart's natural electrical activity (this is called sensing). It also sends electrical impulses to the heart to make the heart beat (this is called pacing). For example, if the pacemaker senses that the heart is beating too slowly or pausing for too long, it sends tiny electrical impulses. These impulses are too slight for you to feel, but they stimulate the heart muscle to contract and pump blood. If the pacemaker senses that the heart is beating at a proper pace, it goes "on demand" and stands by until it is needed. The instant the heart starts beating too slowly or pauses for too long, the pacemaker will begin pacing again. The pacemaker's sensing and pacing functions are adjusted, or "programmed," by your doctor to meet your particular needs.