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A Pacemaker is a small, artificial, electrical device placed in the chest or abdomen to help control abnormal heart rhythms. Pacemakers steady patients’ heartbeats by regulating Sinoatrial node contractions. A Pacemaker is used to treat Arrhythmias and can help patients resume a more active lifestyle.

Pacemakers consist of two major parts: the generator and the leads. The generator is essentially a tiny computer (along with a battery and other electronic components), housed in a hermetically sealed titanium container. Most modern Pacemaker generators are roughly the size of an American 50-cent coin, and approximately three times as thick.

A lead is a flexible, insulated wire that carries electrical signals back and forth between the Pacemaker generator and the heart. One end of the lead is attached to the generator, and the other end is inserted through a vein into the heart. Most Pacemakers use two leads; one is placed in the right atrium and the other in the right ventricle.

Pacemakers are implanted under local anesthesia. The generator is placed under the skin, beneath the collar bone. The leads are threaded through a nearby vein, advanced to the appropriate position within the heart, and their ends are plugged into the generator.

Once implanted, the Pacemaker works by monitoring the heart’s electrical activity, and deciding whether and when to “pace.” If your heart rate becomes too slow, the device paces by transmitting a tiny electrical signal to the heart muscle, causing it to contract. Pacing can be done from the right atrium, the right ventricle, or both. The pacemaker decides on a beat-to-beat basis whether it needs to pace, and if so, in which chambers it should pace. Its’ intelligent pacing makes sure that that an appropriate heart rate is always present, and that the work of the cardiac chambers is always coordinated.

Pacemakers are “programmable,” which means that the specific functions they perform can be altered at any time. Programming a pacemaker is done by wirelessly transmitting new instructions to the generator, using a special device called a “programmer.”

Almost all Pacemakers have the ability to vary the rate at which they pace, depending on your immediate needs. These Pacemakers are called “rate-responsive pacemakers” because they utilize several technologies to determine the optimal heart rate, but two in particular have proven quite useful. One of these is the activity sensor, which detects body movement. The more active you are, the faster the Pacemaker will pace your heart (within a range of heart rates that is set by your doctor). The other method commonly used to vary the rate of pacing is a breathing sensor, which measures your rate of breathing. The faster your breathing, the more active you are (presumably), and faster the pacing (again, within a pre-set range). Either of these technologies allows rate-responsive pacemakers to mimic the normal, moment-to-moment changes in heart rate. Rate-responsive pacing allows patients to be much more active with much less fatigue.

In the majority of people with pacemakers, the hearts own electrical system is actually generating most of the heart beats. The pacemaker is there mainly as a “safety valve,” to prevent occasional episodes of Bradycardia or to override dangerous Tachycardias.