When the normal cardiac rhythm is changed or is very slow, the answer frequently comes in the form of pacemakers – devices that send small electrical impulses to the heart muscle to maintain a suitable heart rate or to stimulate the ventricles. They artificially stimulate the heart and were born out of a necessity to prevent catastrophic bradycardic events. 

The initial pacemaker systems were large, bulky external devices. However, advancements in technology allowed for the development of internally powered, fully implantable devices. Further advancements resulted in even more complex, programmable devices. In recent years, the role of implantable pacing devices has expanded beyond the arrhythmia horizon. Modern pacemakers’ functions include various modes of dual-chamber pacing, rate-response algorithms with dual sensors for optimum physiological response, cardiac resynchronization therapy (CRT), arrhythmia-prevention algorithms, antitachycardia pacing, and hemodynamic monitoring. Modern pacemakers also offer “physiological pacing” algorithms that minimize ventricular pacing and reduce the incidence of atrial fibrillation significantly. The approach to cardiac pacing is continually shifting and evolving and now there are even leadless pacemakers. These are small, self-contained devices that are inserted in the right ventricle of the heart of patients who need single-chamber pacing only.