The pacemaker is a significant medical advancement that regulates heart rhythm. It delivers electrical impulses to the heart, ensuring a consistent and healthy rate. For individuals whose hearts struggle to maintain a regular rhythm, this device alleviates symptoms and extends life. Its development transformed cardiovascular care for millions globally.
Understanding the Need for a Pacemaker
The human heart uses a natural electrical system to coordinate contractions and pump blood. If this system malfunctions, it leads to irregular heartbeats called arrhythmias. These can be too slow (bradycardia) or too fast, hindering the heart’s ability to supply blood and oxygen. Such conditions cause symptoms like dizziness, fatigue, and shortness of breath, and can be life-threatening.
The idea of electrically stimulating the heart to regulate rhythm led to early external devices. In 1950, Canadian electrical engineer John Hopps developed the first external artificial pacemaker. His device sent electrical pulses to the heart, and was successfully tested on a dog that same year. This pioneering work laid foundational groundwork for future cardiac pacing.
Pioneering the Implantable Device
The implantable pacemaker resulted from several innovators’ contributions. Electrical engineer Wilson Greatbatch made an accidental discovery in 1958. While working on a heart rhythm recording device, he inadvertently used a wrong resistor, causing his circuit to produce intermittent electrical pulses mimicking a heartbeat. This outcome became the basis for the first successful implantable pacemaker circuit.
Greatbatch collaborated with surgeon William Chardack to refine and miniaturize the device. Their Chardack-Greatbatch pacemaker was first successfully implanted in a human in 1960. Simultaneously, Earl Bakken, Medtronic co-founder, helped make implantable pacemakers commercially viable. Bakken had developed the first external, wearable, battery-powered pacemaker in 1957. Medtronic commercialized the first implantable pacemaker in 1960, building on Greatbatch’s design and overcoming miniaturization and biocompatibility challenges.
Milestones in Pacemaker Development
Following initial implantable designs, pacemakers underwent significant technological advancements. Battery technology saw a major improvement, transitioning from early mercury batteries to long-lasting lithium-iodine cells introduced by Wilson Greatbatch in the 1970s. These lithium batteries extended pacemaker longevity to over 10 years.
The 1970s also brought programmable pacemakers, allowing physicians to non-invasively adjust pacing parameters for patient needs. This enabled fine-tuning without additional surgery. Dual-chamber pacemakers, pacing both atrium and ventricle in synchronization, were developed by the late 1970s. This innovation mimicked the heart’s natural electrical activity, improving cardiac output. More recently, leadless pacemakers, smaller and implanted directly without wires, have emerged, reducing complications.