© Dittrick Medical History Center, Case Western Reserve University
How a shock to the heart jump-started emergency medicine
The spark of life lies not only at the core of the wonders of science, it is arguably the greatest mystery of human life. The electrical impulse that compels the human heart to beat is at once unknowable and, as it turns out, entirely replicable.
When Mary Shelley’s daring Dr Frankenstein conceived his monster, it took nothing less than the awesome power of lightning to bring a biological jumble of stolen body parts to life. At the time her book was published in 1818, electricity and in particular galvanism — the use of electrical current to contract muscle — were at the forefront of both the public’s imagination and the scientific community’s interest. Strangely, what began as romance and science fiction were fast becoming fact.
Late in the 18th century, Italian physician and philosopher Luigi Galvani (1737-98) had proved that a simple spark of electricity could make the legs of a dead frog dance with life. It was 1791, and the idea that a shock might be used to correct heart problems and even bring the dead back to life was still many decades away, but it was the birth of the study of bioelectricity and scientists soon began connecting the dots that would eventually lead to defibrillation.
In the mid 19th century, German physiologist Carl Ludwig (1816-1895) was at the forefront of cardiology, exposing the inner workings of what made the heart tick — as well as what made it stop. In his lab at Zurich University, Ludwig induced ventricular fibrillation via electrical current in the heart of a dog in 1850. The poor pooch may not have survived, but the notion that electricity and the heart were intricately, exquisitely connected did, inspiring other researchers to pick up the torch.
Researchers in the United States, Europe and Russia simultaneously came to the conclusion that a shock to heart might actually be a good thing, with far-reaching therapeutic benefits. From various labs around the world, devices specifically designed to zap cardiac muscle were emerging. These early capacitors stored an electrical charge, which could be transmitted via a pair of paddles directly to the heart.
At the University of Geneva in 1899, Swiss researchers Jean-Louis Prévost (1838-1927) and Frederic Batelli (1867-1941) were experimenting with single-pulse defibrillation. They were the first to revive animals whose hearts they’d stopped using charged capacitors. A weak current caused ventricular fibrillation, they observed, while a stronger current actually stopped fibrillation and kick-started the heart into action again. The catch, of course, was that none of this was possible without the shock being applied directly to the heart muscle. Since cardiac surgery in humans was relatively unheard of at that point, electrical defibrillation was a wonder well ahead of its time.
MODERN DR FRANKENSTEIN?
Beginning in 1925, thoughtful funding by the Edison Power Company — interested in reducing the rising number of electrocution deaths in linemen who oversaw the wiring of North America in the early part of the 20th century — led to experiments conducted on victims of accidental electrocution.
The research was jointly conducted at Johns Hopkins University by engineer William Kouwenhoven (1886-1975) and several physicians, including neurologist Orthello Langworthy (1897-1996) of the School of Hygiene and Public Health. Throughout the 1930s, the team unravelled the electrical mysteries of the heart, using shocks to induce and the reverse fibrillation in rats and dogs, effectively reviving the earlier work of Prévost and Batelli. The Hopkins team was also the first to test and prove that defibrillation was technically possible simply by shocking the outside of the chest, too.
The notion had been fairly well proven: direct electrical stimulation to a fibrillating heart can get it beating regularly once again. But what therapeutic benefit might this hold? Animal experiments were acceptable, of course, but interference in the workings of the human heart was another story entirely. Fortunately, desperate times call for desperate measures, as one pioneering cardiologist discovered during a crisis in surgery.
Claude Beck (1894-1971), the first professor of cardiovascular surgery in the United States, had developed a keen interest in defibrillation experiments on animals during his time at the University Hospitals of Cleveland during the 1940s. While conducting surgery on a 14-year-old boy with a congenital chest defect who suddenly went into cardiac arrest, Beck attempted the standard therapy, cardiac massage, to halt fibrillation.
He administered drugs and manually pumped the boy’s heart for 45 minutes, but knew the end was near. As a last-ditch effort, Beck sent for his homemade AC defibrillator — its paddles were simply metal tablespoons attached to a boxed transformer unit with a variable resistor to control the current — and successfully shocked the boy’s heart into a normal sinus rhythm once again. Dr Beck literally brought his patient back from the dead, in much the same way as the fictional Dr Frankenstein had animated his monster on that stormy fictional night.
Word of Beck’s success spread like wildfire across the country, and electric defibrillation during surgery began saving human lives almost immediately. Still, the method was crude and often led to heart damage and even broken ribs from having to quickly crack the patient’s chest cavity open to access the heart and apply the electrode paddles directly to its sides.
The early open-chest alternating-current, or AC defibrillators as they were called, were large and bulky units that needed to be plugged in to the wall, and were actually quite heavy to move around. To make matters worse, they were a little too powerful and the current was hard to control, resulting in many injuries, burns and even death. Things changed dramatically with the advent of closed-chest defibrillators, and the introduction of batter-powered devices.
In the 1950s, continued corporate funding by the power companies allowed for the development of the first closed-chest defibrillator by Kouwenhoven and cardiovascular physiologist William Milnor (1920-2008). In 1954, they successfully revived a dog using their device, elevating a last-ditch surgical effort to a miracle-level cardiac cure.
Also in 1954, Paul Zoll (1911-1999) — Chief of the Cardiac Clinic at Beth Israel Hospital in Boston — proved that external defibrillation during a cardiac event was remarkably successful in treating more than just man’s best friend. By increasing the power of the electrical current, shocking a patient's chest directly was indeed enough to restart the human heart and get a stable rhythm going. It was a watershed moment in emergency medicine, dramatically reducing the mortality rate for cardiac arrest and heart disease from that moment on.
AND CPR TOO!
External defibrillation was also a precursor to the birth of CPR. In 1958, Kouwenhoven’s assistant – engineering student Guy Knickerbocker (b. 1932) – noticed that the mere act of placing the heavy paddles on the chest of the dogs they had been reviving during defibrillation experiments caused blood pressure to rise. It was the birth of CPR – and they discovered that repeated manual chest compression worked on humans too, proving it once and for all by saving a woman in cardiac arrest in 1959. For his incredible contributions to medicine, engineer Kouwenhoven was given the first honourary Doctor of Medicine by Johns Hopkins.
In 1960, the direct-current (DC) defibrillator was introduced by cardiologist and Nobel-Prize winner Bernard Lown (b. 1921) of Harvard University, while Seattle cardiologist Karl William Edmark (1924-1994) of the University of Washington came up with a DC device as well. These lower-voltage units that no longer had to be plugged into the wall were far safer and smaller than the earlier AC versions, which damaged tissue and all-too-often jolted patients to death.
Technology greatly reduced the size of the machines during the 1960s and ’70s. Before long, portable defibrillators were everywhere. Non-physicians and even lay people could be trained in their use, making their presence ubiquitous everywhere emergency medicine was happening: ambulances, airplanes, athletic events and remote clinics. As the digital age in medicine was ushered in and computer technology elevated these once basic boxes into sophisticated machines, defibrillators have saved countless lives around the world.
Once it became clear that electricity was so effective in regulating heart rate and even resuscitating patients on the brink — or even past — the point of no return, it didn't take long for physicians and researchers to push the idea of the defibrillator even further by permanently implanting miniature versions directly inside cardiac patients' chests.
From the cataclysmic power of lightning to the microscopic miracles that keep countless cardiac patients alive on a daily basis, the ability to control the power of electricity to cure what ails the human heart has been nothing short of revolutionary.
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