uently from previous heart attacks. Sometimes it is simply caused by aging of the conduction system.Pacemakers come in different shapes and sizes. All of them are small and lightweight. Depending on the patients heart condition, the physician will prescribe the number of chambers to be paced and a specific kind of pacing. A single-chamber pacemaker paces either the right atrium or the right ventricle with one lead. Single lead pacemakers are used primarily in three situations:1. When the only problem is with the formation of the initial impulse in the atrium, simply placing a lead in the right atrium will start things off when it is needed, and the electrical impulse will then continue normally throughout the rest of the atrium and the ventricles.2. When the patient is in chronic atrial fibrillation and the ventricle is going too slow. In this case, only a single lead is placed in the ventricle.3. When the problem with a slow rate occurs only occasionally and for relatively brief periods of time, a single lead in the ventricle may be all that is utilized to provide brief help at those times.A dual-chamber pacemaker has one lead in the right atrium and one in the right ventricle. This pacemaker keeps the upper and lower heart chambers contracting in their proper sequence. This style is the most common pacemaker used today. A rate-responsive pacemaker is needed when a heart cannot appropriately increase its rate according to a persons needs. This type of pacemaker varies its rate depending upon a persons level of activity, respiration, or other factors. Rate-responsive pacing can be a part of single-chamber and dual-chamber pacing. Normal heart rhythms slow down or speed up many times during the day. The heart beats slower while resting or sleeping. Exercise or emotional excitement makes the heart beat faster because the body requires a greater amount of blood circulation. Rate-responsive pacemakers use special sensors that re...
