A Shock To The System
A 62-YEAR-OLD MAN IS WALKING THROUGH a shopping mall, searching for a birthday present for his wife. Suddenly a lightness, a dizziness, fills his head. He quickly sits down, but the sensation doesn’t go away. He feels himself shrinking, like a balloon with the air rapidly escaping. Sounds reach him down an echoing corridor. He slumps to the floor. Before passers-by can react, he is clinically dead: His pulse and breathing have stopped. His brain, starved of oxygen, slips into unconsciousness.
Although the man has experienced sudden cardiac arrest, his heart has not simply come to a standstill. Instead it has fallen into a pattern of electrical activity that results in frenzied, chaotic motion but pumps no blood. Surgeons vividly describe such a heart as a sack of writhing worms. When first identified in 1850, the phenomenon was called intervermiform, or wormlike, movement. At the time, it was a curiosity. Today, known as ventricular fibrillation, it is recognized as the leading cause of death in industrial countries, one that kills an estimated 1,000 Americans every day.
A bystander checks the man’s vital signs and administers cardiopulmonary resuscitation (CPR). The CPR does not reverse the electrical disturbance, but it buys time, keeping the organs supplied with a trickle of oxygen. Now two paramedics rush in. They cut open the man’s shirt and slap a pair of sticky pads onto his chest. Wires lead from the pads to a machine with the inelegant name of defibrillator. A heart monitor shows the ragged pattern of what’s known in emergency medicine as v-fib. The only antidote is electricity.
When the paramedic presses a button, the machine sends 2,000 volts through the electrodes for a fraction of a second. Part of the current travels through the heart itself, stunning the quivering fibers into stillness. A moment later the heart’s internal pacemaker, a little knob of tissue near the top, reasserts itself. Coordinated contractions push blood into the man’s arteries. He draws a breath and coughs. He is alive again.
The first detailed investigation of ventricular fibrillation was carried out by the Scottish researcher John MacWilliam in work he published in 1889. Even without the advantage of an electrocardiogram, he was able to track down the true cause of the “fatal syncope” that had long puzzled doctors. It was an electrical malfunction, not an injury, that caused the heart to fail. “Sudden cardiac failure does not usually take the form of a simple ventricular standstill,” he stated. ”… Instead of quiescence, there is a tumultuous activity, irregular in its character and wholly ineffective.” His discoveries began the modern study of resuscitation.
MacWilliam was the first to show that the heart is a self-contained electrical unit marching to its own drumbeat, a rhythm produced in little nodes in the atria. When this electrical pacing system breaks down, anarchy results. Individual fibers send out their own electrical signals, firing feverishly but without effect. The heart, in essence, electrocutes itself.
In popular parlance, the victim dies of a “massive heart attack.” The cause of such an event is often unclear; research has shown that fewer than half the cases of sudden death are brought on by a blockage of coronary arteries. Diseased hearts are susceptible to v-fib, but it is sometimes impossible to pinpoint the true cause of this always transient event.
The modern defibrillator began, literally, as a footnote. In 1899 two Swiss physiologists, Jean Louis Prévost and Frederic Battelli, were studying the detrimental effects of electricity on the hearts of dogs. They published a paper detailing how a shock of 40 volts could send the heart into ventricular fibrillation, refuting the notion that death from electrocution was a result of respiratory paralysis. At the bottom of the page they mentioned that a stronger jolt, from 240 to 4,800 volts, would cause the quivering to cease, bringing the dog back to life. The reason why this is so remains something of a mystery to this day.
News of their discovery sat virtually unnoticed on the shelves of academic libraries for decades. Yet interest in remedies for v-fib had been growing over the latter part of the nineteenth century as more patients died from the effects of general anesthesia. Chloroform could send patients’ hearts into fibrillation, and surgeons had to stand by helplessly and watch their patients die.
In fact, clues to the value of electricity in resuscitating heart attack cases had been around for more than a century before the Swiss researchers made their discovery. On June 18, 1782, an elderly Englishman “was struck by lightning, thrown from his chair, and taken up for dead. In this hopeless state electrification was performed by a skillful practitioner … by which efficacious remedy the man was happily at length restored to Life.” While it is far from clear whether this case, and other accounts of electrical resuscitation recorded by the Royal Humane Society of London, were truly examples of defibrillation, they do point to early attempts to use electricity to save those in a lifeless state. In 1788 Charles Kite, a London medical innovator, published a diagram of a device remarkably like a modern defibrillator, with a Ley den jar as a capacitor and two insulated knobs for electrodes. “Electricity,” he concluded, “is the most powerful stimulus we can apply.”
Enthusiasm about resuscitation was high at the time, and all kinds of techniques were tried. Victims were hung upside down, pommeled, rolled over barrels, laid across the saddles of trotting horses, and given anal infusions of tobacco smoke. The prospect of being subjected to some of these nostrums led citizens to sew notices into their clothing announcing, “I suffer from epilepsy—please leave me alone!” Then, toward the end of the eighteenth century, electricity, which had been shown to cause muscles to contract, began to be viewed as a potential reanimator.
As early as 1804 the Italian researcher Giovanni Aldini advocated a combination of artificial respiration and electrical treatment that was very much like modern resuscitation protocols. In 1815 James Curry of England suggested that moderate shocks “should, at intervals, be passed through the Chest in different directions, in order, if possible, to rouse the Heart to act.” His instructions for placing the electrodes are almost identical to modern practice. In 1824 Richard Reece of London described a “reanimation chair,” invented by a man named deSanctis, that made use of Alessandro Volta’s electrochemical battery.
Little of this electrical experimentation carried over into modern medicine. Twentieth-century researchers at first saw electricity as a danger, not a remedy. In 1926 the Consolidated Electric Company of New York kicked off modern defibrillation research by sponsoring investigations into ways to save electrocuted workers. One of those working on the project was the physiologist William H. Howell, of Johns Hopkins University. In 1930 Howell came across Prévost and Battelli’s paper. He took the idea to his team of researchers, who included the electrical engineer William B. Kouwenhoven.
Kouwenhoven was a professorial, pipe-smoking, highly determined researcher who would keep returning to the problem of defibrillation over the next forty years. He and his colleagues R. Donald Hooker and Orthello Langworthy began to look at the effect of electricity on dogs. In 1933 they verified the findings of their Swiss predecessors: An electrical current could indeed end ventricular fibrillation.
But there was a catch. If the shock was delayed more than two minutes, the animal’s oxygen-starved heart would fail to resume its beat after defibrillation. The only way to extend this time was to massage the heart by hand in order to maintain circulation. This hardly seemed practical in the field, for cardiac massage was considered dangerous even in the operating room. The group was stymied. “This 2-min limitation was a real road block,” Kouwenhoven wrote later.
Interest in the subject was spreading, though. Dr. Claude Beck, a large, soft-spoken heart surgeon at Western Reserve University in Cleveland, had followed the Johns Hopkins research. In 1937 he published a paper advocating a standard procedure to deal with v-fib in the operating room: ventilation with pure oxygen, heart massage, and defibrillation with 60-cycle alternating current applied directly to the heart at 110 volts—resulting in a current of 1.0 to 1.5 amps—for up to two seconds. The technique was not widely adopted and remained experimental.
World War II put progress on hold. Then in 1947 Beck was operating on a 14-yearold boy to repair a congenital chest deformity. The boy’s heart went into fibrillation. Beck massaged the organ for 45 minutes while the defibrillator was brought from his research lab and set up. Two shocks resulted in cessation of v-fib. Three hours later the boy was awake and answering questions. Beck had achieved a breakthrough. It was the first modern instance in which an application of electricity had restored a human life.
Early operating-room defibrillators, all makeshift devices, were simple. The instrument Kouwenhoven had put together for use in the Johns Hopkins Hospital began with an isolation transformer to diminish the chances that the current would spark or shock the operator. Next came a variable voltage transformer, or Variac, which allowed the surgeon to dial his desired shock level. A foot switch and pilot light completed the circuitry. Two insulated brass rods with stainless-steel paddles the size of half-dollars served as electrodes. Sterile felt soaked in saline solution covered them when in use. The surgeon applied the paddles to the quivering heart, controlling the duration of the current with the foot switch.
Limitations kept these early defibrillators from being used routinely. During the 1950s open-chest heart massage was the only available means of keeping a person in v-fib alive. Beck encouraged all hospital physicians to carry a scalpel to open the chests of patients in cardiac arrest. Hospitals routinely kept kits at the bedside of heart patients to be ready for such intervention. Beck, ever eager to save “hearts too good to die,” suggested that the bloody technique could be performed on the street, an opinion that led a conservative colleague to label him “not a safe man to have on the faculty.”
In 1951 the problem of electrocuted linemen continued to vex the utilities industry. The Edison Electric Institute, a consortium of power companies, asked Kouwenhoven to develop a closed-chest defibrillator, eliminating the need to cut into a victim’s flesh. “I was told they would place a defibrillator on every line truck and thus circumvent the 2-min limitation,” Kouwenhoven recalled. Trained crew members would apply the defibrillator.
For this application Kouwenhoven and the other researchers in the field faced the problem of delivering the right amount of current to the heart. With open-chest defibrillators this was a straightforward matter, since the electrodes were applied directly to the organ. But the chest, with its bone, blood, and muscle, is a complicated electrical conductor. Enough current had to pass through the heart to bring most of the fibers to rest, but too much current could permanently damage the heart or reinduce fibrillation. Even today the optimum amount of electricity and how to deal with variations in impedance among patients are subjects of debate. Kouwenhoven settled on a charge of around 450 volts, which was found to yield a total current of five amperes in “a barrel-chested man.” Of this, about one ampere passed through the heart muscle, a current roughly equal to that applied by the open-chest defibrillator.
In 1952 Dr. Paul M. Zoll of Boston solved a related problem when he showed that electricity applied to the chest could pace the heart’s beat (see “Many Paths to the Pacemaker,” Invention & Technology , Spring 1997). Zoll and Kouwenhoven proceeded to develop external defibrillators simultaneously. Zoll first used external electrodes to defibrillate a human patient later in 1955, and soon the defibrillator was ready to move out of the operating room—but not far.
Kouwenhoven’s closed-chest defibrillator was equipped with a massive step-up generator to boost the charge to the voltage needed. A timer, a circuit breaker, a few switches, and the three-inch electrodes with insulated grips completed the device. The problem was portability. The Hopkins AC defibrillator weighed 280 pounds and was powered by line current. It could barely be wheeled around the hospital, to say nothing of being lugged into the field.
Most of those struck down by what was now being recognized as an epidemic of heart disease died outside the hospital. Use of the closed-chest defibrillator faced the same severe time constraint that Kouwenhoven had puzzled over in the 1930s. Until that limitation was circumvented, the machine would remain a marginal weapon in the losing war against sudden death. The defibrillator would come into its own only after two more pieces of the resuscitation puzzle fell into place: maintaining the victim’s breathing and pulse.
Artificial respiration has a long history filled with false starts. In 1732 the Scottish surgeon William Tossach, called to the side of a miner overcome by fumes, blew into the victim’s mouth “as strong as I could, raising his chest fully with it and immediately I felt six or seven beats of the heart.” Two hours later the patient walked home. Tossach suggested that his discovery be disseminated to the public as something that “can at least be no harm.”
Rescuers also tried inserting bellows into a stricken patient’s mouth or nostril. A modified version of this approach, a self-inflating bag connected to the patient’s airway, is used today by emergency personnel. But as one researcher put it, “we lost our way in resuscitation for almost a century.” Unfounded fears of causing emphysema or of rupturing the lungs of patients made physicians shy away from bellows. Fear of contagion and concern over the effect of exhaled carbon dioxide caused the mouth-to-mouth technique to lose favor. Medical men also frowned on this “vulgar” form of resuscitation, which had long been associated with midwives. Fashion and misapprehension won out over empirical observation. By the 185Os the two most effective means of artificial respiration had sunk into a long oblivion.
As a replacement the London physician Marshall Hall in 1857 suggested rolling a sudden-death victim from stomach to side to stimulate breathing. There followed 100 years of controversy over artificial respiration, with new procedures gaining popularity every decade or so. By 1953 there were at least 117 different techniques on the books, none of them very effective. A 1951 study sanctioned by the National Research Council had not even considered the mouth-to-mouth approach.
There were dissenters. During a 1946 polio epidemic in Minneapolis, Dr. James Elam had performed mouthto-nose on a dying victim without thinking about it. “I went into total reflex behavior,” he said. In fact he was reviving not only a patient but a long-forgotten resuscitative procedure. By 1954 Elam was lobbying the surgeon general and the Red Cross to support mouthto-mouth resuscitation. The authorities remained unconvinced.
Two years later Elam had a chance conversation with Dr. Peter Safar, an anesthesia expert who had immigrated to the United States from Austria in 1949. Safar began a series of experiments to see if the rediscovered technique worked. He quickly proved that mouth-to-mouth was the most effective approach to maintaining respiration, as well as the easiest to learn. He became its ardent advocate. In 1958 the American Medical Association accepted his view. One more piece of the resuscitation revolution was in place, but maintaining breathing in a patient with no pulse was futile, while open-chest heart massage was impractical. Another element was needed to complete the equation.
Back in the defibrillator lab Kouwenhoven, now retired as an engineering professor, was trying in 1958 to determine how long a dog’s heart could remain in fibrillation and be revived by a closed-chest shock. With his assistant, G. Guy Knickerbocker, Kouwenhoven hooked a blood-pressure gauge to one of the dog’s arteries. Knickerbocker made a chance observation: When he pressed down with a defibrillator electrode to get better contact, the gauge jumped. Repeated thrusts produced repeated spikes—a pulse. Further experimentation revealed that the same effect could be achieved with just hand pressure.
Kouwenhoven recognized that the finding could be valuable. It was a way of maintaining circulation without opening the chest. The medical community, though, was skeptical.
Dr. James Jude, a resident in cardiac surgery who had joined the pair’s research group, tested the method on patients. He found it to be an effective way to extend the period of viability during which the heart could be defibrillated. The three men published their results in 1960, stating, “Anyone, anywhere, can now initiate cardiac resuscitative procedures. All that is needed is two hands.” That paper, according to one medical historian, “may have resulted in saving more lives than any other medical manuscript during the past century.”
“The roadblock had been cleared,” Kouwenhoven wrote later, “the time limitation had been overcome, and the closed-chest defibrillator had become a versatile tool.”
Once again it was a case of rediscovering a lost art. As early as 1858 a Hungarian surgeon named Janos Balassa had resuscitated an 18-year-old woman during a laryngotomy using chest compressions. Other physicians used the technique sporadically during the late nineteenth century. The Cleveland surgeon George Crile revived a 28-year-old goiter patient this way in 1904. But these isolated cases were not seized on by the medical community, and the procedure faded for the next 50 years.
In the early 1960s advocates led by Dr. Safar combined chest compression and mouth-to-mouth breathing to create modern cardiopulmonary resuscitation. As laypeople began to learn this effective technique for sustaining hearts in v-fib, the opportunity to revive victims of cardiac arrest multiplied. But speed remained the key element. The need to make defibrillation quickly available to victims became paramount.
During the 1950s Kouwenhoven was still intent on inventing a device that would fulfill the mandate of the electric utilities: portable, so that it could be carried on line trucks, and safe, so that it could be used by a layperson without fear of harming a victim whose heart was still beating.
In Seattle the heart surgeon Karl W. Edmark, a sparetime inventor, was working on a similar idea. In 1955 he put together the first battery-powered prototype of a direct-current defibrillator and tested it on dogs. Six years later he wheeled the device into the operating room and used it to defibrillate a patient. Because a burst of only 3 to 5 milliseconds of current was needed, compared with 200 milliseconds of alternating current, the DC defibrillator was vastly safer. Patients barely twitched. Bernard Lown at Harvard was doing similar work at the time and shares credit for making the DC defibrillator the standard.
Around the same time, Kouwenhoven finally reached the goal of a search begun in 1926. He devised a portable suitcase-sized DC defibrillator that weighed 50 pounds and could be powered by line current or by plugging into the electrical system of a truck or an ambulance. A transformer stepped the current up to 2,000 volts and stored the energy in two capacitors. When an operator pressed the paddles to the patient’s chest, first one, then the other capacitor discharged, sending current through the electrodes in two directions. The idea was to mimic the waveform of alternating current, which was known to be effective (though DC eventually won out).
During the 1960s and 1970s Dr. J. Frank Pantridge, of Belfast, Northern Ireland, originated the idea of bringing sophisticated aid to victims of heart attack. His concept of the mobile coronary care unit, or heartmobile, spread quickly in the United States. Innovators like Dr. Leonard Cobb, in Seattle, trained firefighters to read the defibrillator monitor and apply the shock. The profession of paramedic was born, as defibrillation began to be available where it was needed.
But while putting the machines on ambulances brought patients the benefits of defibrillation more quickly, the inevitable delay still kept many heart attack victims from being saved. CPR alone was no panacea. Once cardiac arrest occurred, the patient’s chance of survival declined about 10 percent each minute. By the time the paramedics arrived, death was usually an accomplished fact.
Beginning in 1967, the surgeon Arch W. Diack of Portland, Oregon, took the next step in defibrillation: making the machines automatic. In the early 1970s Diack and his colleagues waded through endless trial-and-error testing of circuitry, voltages, and other components. They reported the first successful use of the devices in 1979.
Diack’s original machine used analogue circuitry to analyze the electrical signals coming from the patient’s heart. The machine needed not only to recognize the electrical pattern of v-fib but also to identify reliably when a shock was not called for. Microchips and digital technology made that task far more precise.
Other companies rushed to add computers to their defibrillators. By the mid-1980s the automatic external defibrillator (AED) was becoming widely available. Its main advantage was that it required far less skill: The user didn’t need to know how to read an electrocardiogram. As a result, operator training was reduced from 12 hours or more to 3 hours. The AEDs were also shown to allow a quicker delivery of shocks and to enhance operator safety.
Defibrillator technology had already taken an additional step. In 1980 the device was miniaturized sufficiently to be implanted in the chest of a person known to be at risk for sudden death, usually because the patient had already been through one potentially fatal attack. Incipient fibrillation could be instantly stilled by a small charge directly into the heart.
During the 1990s external defibrillators have also gotten much smaller, and they can now recognize patterns more accurately than a trained technician. Yet the overall rate of survival from cardiac arrest has barely changed since the 1970s. Time remains the hurdle. Local studies have shown that if defibrillators were more widely available, many lives could be saved. In a Las Vegas research project, security personnel in casinos were trained to use AEDs. They cut the average response time for stricken gamblers to three minutes and scored a 70 percent survival rate, compared with only 5 percent nationally. In Rochester, Minnesota, where all police cars carry defibrillators, 45 percent of victims survive cardiac arrest.
The American Heart Association has been pushing for much wider distribution of AEDs. Some airlines have started to stock them on planes. Sports stadiums, offices, and shopping malls are other targets. The newest AEDs weigh four pounds, are the size of a hardcover book, and give voice instructions to the operator. They cost from $3,000 to $4,000 each. Many in the industry think that economies of scale can bring the price as low as $500 and that the day may come when many homes will be equipped with the devices.
Because ventricular fibrillation is one of the most common causes of death, defibrillation has been called “the single most important medical intervention.” While sudden death will always claim its share of victims, the widespread availability of defibrillators will at least provide a potent weapon, and a ray of hope, in an age-old struggle.