If the heart is unable to maintain a regular rhythm, symptoms may occur. A normal heart rate or pulse is between 60 to 80 beats per minute. However, many medical conditions can make the heart beat too slow, too fast, skip beats or stop periodically. Irregular heart rhythms can lead to chest pain, shortness of breath or dizziness, and can increase the risk of a heart attack or stroke. In these cases, it may be necessary to have a pacemaker implanted to help the heart maintain a regular rhythm.
Battery
Pacemakers are powered by a battery that's located in the generator. According to the Texas Heart Institute, most pacemaker batteries last about seven to eight years. When the battery dies, the generator must be replaced. The activity of the pacemaker must be monitored during office visits and over the phone. A physician can use a device called a programmer, which is held over the skin where the pacemaker is located. The programmer can detect how well the device is working and whether the battery must be replaced.
Generator
The London Cardiac Institute says the main part of a pacemaker is the generator, a small device about the size of a pager. The generator houses the battery and records the electrical activity of the heart. Based on the information it receives, it decides whether to send out an electrical impulse if the heartbeat is irregular. This part of the pacemaker is usually placed near the shoulder, collarbone or chest and is inserted through a small incision. If the heartbeat is too fast, the generator stops sending impulses until the heart slows down. When the heartbeat gets too slow, the generator sends out impulses to speed it up.
Wires
A pacemaker also contains wires that carry electrical impulses to and from the heart and generator. The National Heart, Lung and Blood Institute says the number of wires a pacemaker has depends on the heart condition that's causing the irregular rhythms. The heart consists of four chambers--two upper chambers called atriums and two bottom chambers called ventricles. Different conditions cause different chambers of the heart to not contract correctly. If the problem is occurring in the right ventricle, the pacemaker has one wire between the generator and the right ventricle. A two-wire pacemaker connects the generator to the right atrium and the right ventricle. A three-wire pacemaker attaches to the right atrium and the two bottom ventricles. A cardiologist determines how many wires are needed, based on the medical condition that's causing the symptoms. Whenever the pacemaker needs to be replaced, a surgeon can check the wires to see if they also need replacement.
