Artificial cardiac pacemaker

The concept of electrical cardiac stimulation dates to the 19th century, but the first practical external pacemaker was developed in 1952 by Paul Zoll, who used electrodes on the chest wall. In 1958, Åke Senning and Rune Elmqvist implanted the first fully internal pacemaker in a patient in Sweden; that device lasted only hours, but subsequent models improved rapidly. The introduction of lithium-iodine batteries in the 1970s extended device longevity, and microprocessor-based programming in the 1980s allowed noninvasive adjustment.¹

Pacemakers are indicated for symptomatic bradycardia, high-grade atrioventricular block, and certain forms of heart failure (e.g., cardiac resynchronization therapy). Devices are classified by the number of chambers they stimulate: single-chamber (atrial or ventricular), dual-chamber, and biventricular. Rate-responsive pacemakers adjust pacing rate based on physiologic sensors such as activity or minute ventilation. Temporary pacemakers are used in emergencies or post-cardiac surgery, often via transcutaneous or transvenous routes.²

Implantation is typically performed under local anesthesia with fluoroscopic guidance, with the pulse generator placed in a subcutaneous pocket near the clavicle. Leads are advanced transvenously into the right atrium or ventricle. Complications include infection, lead dislodgement, pneumothorax, and venous thrombosis. Long-term issues include lead fracture, insulation failure, and device erosion. Electromagnetic interference from MRI, diathermy, and certain industrial equipment can affect function, though MRI-conditional devices are now available.³

Early pacemaker pioneers faced skepticism; the first implant in 1958 was performed without prior animal trials. The term "pacemaker" was coined by Albert Hyman in the 1930s, who built a device that was never used clinically. In 1960, Wilson Greatbatch developed a reliable implantable pacemaker using a mercury-zinc battery, but its short life required frequent replacements. Modern innovations include leadless pacemakers, which are self-contained units implanted directly into the right ventricle, and subcutaneous ICDs that combine pacing and defibrillation. Additionally, pacemakers have been used experimentally in non-cardiac applications, such as gastric pacing for gastroparesis.⁴

Bradycardia

A heart rate slower than 60 beats per minute.

Atrioventricular block

A conduction disorder where electrical signals are delayed or blocked between the atria and ventricles.

Lead

An insulated wire that connects the pulse generator to the heart.

Pulse generator

The battery-powered electronic circuit that produces the electrical impulses.