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The Complete History of AEDs & External Defibrillation

In 1775, a Dutch veterinarian named Peter Abildgaard used electricity to stop—and then revive—the heart of a chicken, thus proving once and for all that electricity could be used to manipulate heart rhythms. Ever since then, scientists have been working diligently to master the art of defibrillation, the process of using controlled electric shocks to restore normal heart function in cardiac arrest sufferers.

Today’s automated external defibrillators are capable of assessing heart rhythms, coaching users in real time, and administering automatic or semi-automatic shocks. We take for granted how intuitive these devices are, but it’s been a long and complicated journey from zapping chickens to defibrillation-on-demand. The complete history of AEDs is complex and compelling.

The Early Days of Defibrillation in Animals – 1899-1946

Starting around the turn of the 20th century, cardiac arrest became a leading killer nationwide. Ironically, the condition became common because people were getting healthier. That is, they were suddenly living long enough to develop debilitating heart disease. Infectious diseases no longer ruled the day.

As cardiac arrest became a growing worldwide concern, scientists concerned themselves with how to revive a failing heart. Expanding on the animal research conducted by earlier medical professionals, two physiologists at the University of Geneva—Jean-Louis Prevost and Frederic Batelli—came together in 1899 and conducted a series of successful defibrillation experiments on dogs. Though they weren’t the first researchers to stop and restart an animal’s heart, they were instrumental in identifying the role of ventricular fibrillation as a cause of cardiac arrest.

In the 1940s, two Soviet doctors, Dr. Naum Lazarevich Gurvich and Dr. G.S. Yuniev, expanded on this knowledge and proposed the first defibrillation waveform. This waveform, now referred to as biphasic waveform technology, is used even today in some of the world’s best AEDs. Biphasic waveforms deliver shock via two separate vectors, reducing the defibrillation threshold and improving patient outcomes.

In 1946, Gurvich and Yuniev put their theories into practice and completed the first closed-chest defibrillation on a mammal—a dog, specifically. In other words, they were able to revive the animal by applying electrodes to the surface of the chest without opening the chest cavity to access the heart organ directly. This was a huge step forward.

The First Defibrillation in Humans – 1947-1950

Less than a year after Gurvich and Yuniev captured the world’s attention with the first closed-chest defibrillation on a mammal, an American cardiac surgeon named Claude Beck would prove the viability of defibrillating human beings.

For Beck, the mission was personal. He had been heavily invested in fibrillation research since the late 1920s, when he lost a patient to ventricular fibrillation. Throughout the 1930s and ‘40s, he studied and experimented with methods of improving heart circulation and treating fibrillation with manual heart massages.

He became interested in electrical defibrillation after studying the successful animal experiments of colleagues like Carl J. Wiggers at Western Reserve (now Case Western Reserve University). He was convinced that such experiments could be replicated in humans and perfected to save lives.

In 1947, Beck and a group of investigators at the University Hospitals in Cleveland, Ohio, completed the first open-heart defibrillation on a human being. The patient, Richard Heyard, was a 14-year-old boy being treated for a congenital chest defect. His heart entered ventricular fibrillation near the end of his procedure, and manual massage did nothing to stop the problem. With no other options, Beck connected two electrodes to Heyard’s open heart and shocked it four times at 110 volts. The heart rhythm was restored, and Heyard made a complete recovery.

The story made worldwide news headlines. One such headline read, “How Science Brings Americans Back from the Dead.” From that point on, Beck dedicated himself to improving electrical defibrillation for use on human beings. He developed the original prototype defibrillator, which—though monumental for its time—was little more than a large wooden box with two metal electrodes attached.

Beck and his colleagues would ultimately go on to develop some of the CPR practices that are still used today. They trained over 3,000 doctors and nurses in CPR and ultimately developed a CPR course for laypersons as well. His work represents a turning point in the history of AEDs.

The First Portable External Defibrillators – 1950-1956

While Beck and his colleagues worked on improving defibrillation in hospitals, another doctor, William Kouwenhoven, was working on developing a more portable solution. Kouwenhoven was the dean of the School of Engineering at Johns Hopkins University, and he was known for his successful open-heart defibrillation experiments on dogs. In the early 1950s, he started experimenting with DC-powered portable defibrillator designs. At the time, though, there were no DC batteries powerful enough to create the necessary charge for closed-heart defibrillation.

In 1951, Kouwenhoven started exploring AC power instead, and he was finally on his way to developing a sustainable portable defibrillator. By 1957, he finished work on one of the original closed-chest defibrillators for human use. The device used AC electricity to deliver 480-volt shocks safely to the adult heart. The only problem was that it weighed over 250 pounds (120 kg), which made it completely impractical as a portable device. Still, Kouwenhoven and his team kept innovating, and by 1961, they developed the first truly portable defibrillator. It weighed about 45 pounds and was capable of fitting into a small suitcase.

Though Kouwenhoven’s contributions were monumental, his legacy would ultimately be overshadowed by that of Paul Zoll, one of his contemporaries who was also researching portable defibrillation. Zoll, who’s recognized today as the Father of Modern Cardiac Therapy, became interested in treating ventricular fibrillation in 1947. Like Beck before him, his interest was ignited after he lost a patient to cardiac arrest.

His radical ideas—like his preference for closed-chest over open-chest resuscitation and his use of direct current countershock to stimulate heart activity—were met with resistance and even ridicule in the 1950s, but these techniques would ultimately become the hallmarks of external defibrillation practices used even today.

In 1952, Zoll used external defibrillation to resuscitate two cardiac arrest patients. Though the first patient only survived 20 minutes, the second lived for nearly a year after being revived. Zoll continued to develop his techniques, and by 1956, he developed a new closed-chest method of safely defibrillating patients with a much larger shock, as much as 750 volts.

Zoll and Kouwenhoven developed their closed-chest devices within months of one another, and while both doctors changed the face of cardiac treatment, it’s Zoll’s once-controversial techniques that have stood the test of time and influenced generations of cardiac researchers. In 1980, Zoll co-founded ZOLL Medical, and ZOLL AEDs continue to raise the bar even today.

The First Portable Defibrillators in the Field – 1965-1969

Though Zoll and Kouwenhoven experimented with portable defibrillation in the 1950s, the world wouldn’t see such a device in the field until the mid-’60s. In 1965, Irish physician and cardiologist Frank Pantridge developed a 150-pound portable defibrillator for use in a Belfast ambulance. It was powered by car batteries.

By 1968, Pantridge developed an improved portable defibrillator that weighed less than 7 pounds and was powered by a miniature capacitor designed by NASA. This small, lightweight device is often considered the first true portable AED on account of its size and power.

Starting as early as the late 1960s, Pantridge’s innovative designs were adopted in hospitals and ambulances throughout the world. Surprisingly, though, the technology caught fire internationally before it became a mainstay of his own homeland. Defibrillators wouldn’t become standard in all UK ambulances until 1990.

The Modern History of AEDs – 1978 to the Present

Even as portable defibrillators became a reality in the 1960s, it would be years before such devices would be available to the general public. There were understandable concerns about entrusting untrained laypersons with equipment capable of emitting hundreds of volts of electrical shock to the heart.

The solution would come from a group of colleagues in Portland, Oregon, in 1978. Physicians Arch Diack and W. Stanley Welborn collaborated with engineer Robert Rullman with the goal of developing a foolproof portable defibrillator that bystanders could safely use in an emergency.

And so they developed the Heart-Aid, the first commercially available AED designed for minimally trained lay-providers. The device contained a specially designed sensor that an operator could insert into the patient’s airway. The sensor could detect if a patient was breathing (and therefore not in cardiac arrest) and would then cease operations. A computer chip could also detect heart rate activity from the electrode and determine if a shockable rhythm was present.

An adhesive electrode pad made the device safe for untrained users, as it allowed the user to take a hands-off approach and avoid the kind of accidental shock that could result from improperly operating a paddle. Finally, the device was equipped with real-time voice coaching, so an untrained user could listen along and deliver emergency treatment.

Although the Heart-Aid never became a major commercial success, it set the foundation for the modern automated external defibrillator. Every AED currently in production relies on conventions that originated with this device, including the use of adhesive pads, heart rhythm assessment, and voice coaching.

The history of AEDs is still unfolding. Today, most devices weigh around 3 pounds—a far cry from the 250-pound “portable” defibrillator developed by William Kouwenhoven. Many deliver automatic shocks, and most are available for home use. They’re low-maintenance, easy to operate, and constantly improving as new technologies emerge.

If you ever need to use one of these devices, you can thank the tireless research and experimentation of innovators like William Kouwenhoven, Claude Beck, Frank Pantridge, and Paul Zoll.

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