Scientists, poets, mystics and lay-people alike have long been fascinated by the human heart and, as Van Morrison put it, its “inarticulate speech.” The organ has a rich history as home to the soul, moral compass, seat of emotions and essence of life. Only more recently have we come to understand the heart's electrical pathways, knowledge culminating in the development of an artificial heart regulator called the pacemaker. Shaped by many different hands (and hearts), this life-saving electrical device has steadily improved since the primitive models of the early 1950s, shrinking in size as it grew in reliability, complexity and popularity.
Early incarnations of the pacemaker resembled little the advanced models in use today, but all were based on the same idea: that administering an electric shock directly to or near the heart could stimulate it to contract. This artificial stimulus mimicked the electrical signals normally initiated by the sinoatrial (or sinus) node in the right atrium of the heart. This specialized bunch of cells is the body’s natural pacemaker, but can become damaged or made sluggish by a variety of diseases, medications and traumas. Enter the artificial pacemaker.
The first model, developed in 1950 by John Hopps, John Callaghan and Wilfred G. Bigelow, was external and plagued by problems (not the least of which was its size — as big as a television set!). The early electrodes, powered by a plug-in AC current that tethered the patient to a wall outlet, elicited a painful shock that also damaged the skin. Then, in Minneapolis in 1957, a major advancement arrived in the form of electronics repairman Earl Bakken’s “wearable” pacemaker. The design was inspired by Northwestern Hospital’s pioneer open-heart surgeon Dr. C. Walton Lillehei. After the death of a patient whose AC pacemaker failed during a power outage, Lillehei implored Bakken for an alternative. Working in the cramped garage office of his struggling medical equipment repair business, Medtronic, Bakken developed a prototype about the size of a paperback that could be strapped around the chest or looped though a belt. Most importantly, it was powered by batteries. Bakken’s was also the first pacemaker to use a transistor, a device invented in 1947 that can switch a circuit on and off by letting current through or blocking it. This capability made transistors perfect for pacemakers, which use periodic doses of electrical current rather than continuous flow to make the human ticker tick.
Soon, the pacemaker was moving up in the world and down under the skin with subcutaneous parts, such as leads that reached closer to the heart via veins or were tacked to the heart tissue itself. This reduced the intensity of the shock needed to about 2 volts. Naturally, the idea of an entirely internal pacemaker followed, with the first implant performed in Sweden in 1958 by Dr. Ake Senning. The device, designed by Rune Elmqvist and implanted in the patient’s abdomen, was the size of a can of Kiwi brand shoe polish (a tin of which actually served as Elmqvist’s mold) and lasted a few hours before failing. It was replaced the following morning with another, which had better success. The patient received a total of 26 pacemakers throughout his life and lived to be 86.
Though Elmqvist’s pacemaker and its leads (which were sewn into the myocardial tissue of the heart) were internal, the batteries were still charged by an external coil via induction. The first totally implantable pacemaker was designed by William Greatbatch … by mistake.
While working on a device in the late 1950s that could help record fast heart sounds, Greatbatch reached into a box of resistors without looking and grabbed the wrong size. When he ran his electrical circuit, it pulsed. Then stopped. Then pulsed again. With this simple assembly error, the proverbial lights came on for Greatbatch, who recognized the circuit pattern as a mimicked heartbeat and began work on his pacemaker design. Complete with batteries with a lifespan of three to five years, the pacemaker was implanted in 1960 at the Veterans Administration Hospital in Buffalo, New York, by Drs. William Chardack and Andrew Gage. Patented as the Chardack-Greatbatch implantable pacemaker (pictured above), the device, which used an oscillating circuit, was manufactured and marketed by that same struggling medical equipment repair company, Medtronic, now a major corporation that still sells pacemakers.
In 1983, the National Society of Professional Engineers called the Chardack-Greatbatch implantable pacemaker “one of two major engineering contributions to society during the last fifty years.” While older models were limited to a pre-set heart rate, today’s complex models can, by sensing movement and changes in breathing, adjust heart rate to correspond to activity levels. No bigger than the face of your wristwatch, today’s pacemakers are powered by longer-lasting, corrosion-free lithium batteries (developed by the same Wilson Greatbatch) and can even be monitored and adjusted externally via a computer. Use of the pacemaker has branched beyond cardiology into fields such as pain management and treatment of seizures. With more than 200 million implanted since 1960, the little-device-that-could is one of the most important weapons in the war against heart disease, the number one cause of death in the United States today.
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