STARS:Inventing the Computer
Author: Paul Ceruzzi
As a result of the pioneering work of many scientists, engineers and doctors, the fully implantable pacemaker was invented and developed in the mid 20th century. This is a medical device that uses electrical impulses to keep a human heart pumping, when the internal electrical timekeeper of that heart has failed. By the end of that century, some 100,000 artificial pacemakers were being implanted annually worldwide into patients, almost all of whom benefitted from lengthened and enhanced lives.
An interest in the interaction between living organisms and electricity dates back to the beginnings of electrical science. Luigi Galvani’s anatomical experiments in the late 18th century led him to observe that an electric spark could cause the muscles of dissected frog to twitch. The growing knowledge of the human body led to experimentation on a wide range of electrotherapies—by pioneering scientists and physicians, and also by quacks. These techniques employed both direct current and static electricity, and it soon became clear that the heart was an organ especially sensitive to electricity.
As early as 1788, attempts were made to treat irregular heartbeats with an electric shock, and in 1872 T. Greene in England published an important but sometimes overlooked paper showing that electric shock could restart a stopped heart. By 1878 Munich surgeon Wilhelm von Ziemssen discovered that periodic pulses of DC current applied to the chest could cause the heart to accelerate until its beat coincided with the external stimulus. John Alexander McWilliam then proposed in 1889 that small, regular electric pulses could be used to treat conditions where the heart was beating irregularly or at the wrong rate. In 1899 he published key experiments demonstrating his thesis that regular heart rhythm could be evoked by applying regular impulses.
Impact of AC Power
With the spread of AC power and its dangerous high currents in the late 19th century, researchers began to study why and how electric shocks could be fatal. They came to realize that it was the result of heart failure. Jean Louis Prevost and Frederic Battelli in Geneva and Richard Hoope Cunningham in the United States then discovered that rapid application of a second large shock could sometimes restore the heartbeat and return the victim to life, in a manner somewhat analogous to jump-starting an automobile. One problem was that often the heart would stop again. Physicist Edgar H. Booth and surgeon Mark C. Lidwell in Sidney, Australia, developed an AC-powered apparatus which could deliver large shocks to the heart at regular intervals. In 1928 they used it for ten minutes on a stillborn infant, who subsequently recovered. It became clear, however, that there were two closely related but separate challenges: 1) defibrillation, that is, starting a stopped heart, and ultimately being able to artificially stop and start a heart during surgery; and 2) correcting the heart rate of a heart that was not stopped, but not functioning properly either.
Albert Salisbury Hyman, a New York cardiologist, took up the second challenge. In 1932 he described an electromechanical instrument of his own invention that was powered by a spring-wound hand-cranked motor and delivered, by means of a needle, a regular small pulse to the right atrial area of the sinus node where the heart’s natural pacemaker is located. Hyman coined the term "artificial pacemaker" to describe it, and conducted animal experiments and perhaps one clinical trial, but was unable to interest manufacturers. The medical establishment resisted his technique because of the difficulty and danger of placing a needle directly into the heart. He did eventually manage to produce a few copies of the machine, dubbed the “Hyman meter,” but its medical impact was small
Hyman’s partial success led a team from the University of Toronto to take up the challenge of pacemaking. In 1950 cardio-thoracic surgeons John C. Callaghan and Wilfred Gordon Bigelow of the University of Toronto and the Toronto General Hospital persuaded the Canadian National Research Council to assign an engineer, John A. Hopps, to work on the problem. The argument was made that there was a risk to national security with soldiers experiencing slowing of the heart upon exposure to extreme temperatures. The team improved on Hyman’s work by developing an AC-powered device using vacuum-tube technology to provide pacing to the heart from outside the body, and successfully demonstrated it on canine subjects.
This work in turn inspired Paul Maurice Zoll, a Boston surgeon who had been working on defibrillation. He realized that some of the improvements made by the Toronto team could be used to help his own defibrillation work, but he also saw how the knowledge he had been acquiring could be applied to pacemaking. He built an improved device, and in 1952 he kept alive a 65-year-old man with recurrent cardiac arrest by external stimulation for 52 hours. The patient survived for six months. Zoll’s seminal publication in the New England Journal of Medicine led to the recognition of pacemaking as a fruitful area for future research.
The main drawback of the pacemakers made by the Toronto group and by Zoll was their size. Although they were portable in the sense that they could be wheeled into the patient’s room—unlike, for example, an x-ray machine where the patient must be brought to the device—they were large and cumbersome, and the patient had to be constrained. Another major problem was the power source. Using AC because batteries could not effectively power such large instruments, the devices required the patient to be plugged into the wall.
Late in 1957 Dr. C. Walton Lillehei, a pioneer in open-heart surgery at the University of Minnesota, asked Earl E. Bakken, co-founder of Medtronic, Inc. (a small, local medical instrumentation firm) if it would be possible to develop a battery-operated pacemaker. Bakken realized that the recently developed solid-state electronics was the answer. Within four weeks he had produced a prototype that could be worn on a belt, with the leads running up to the chest. By having the leads penetrate the chest, there was no problem with the patient being ambulatory, and even smaller batteries could be used. Almost immediately Lillehei used it for treating children who had developed heart block after surgery, and he published his results in a major medical journal. This wearable, transistorized unit was produced commercially as the Medtronic 5800 pacemaker. Initially limited to a few hundred units, this pacemaker liberated patients from their power-cord tethers, demonstrating once and for all the safety and effectiveness of pacemaking as a medical technology. As a result, Medtronic became well established as a manufacturer of medical devices and perhaps the industry leader in external pacemakers.
The next significant challenge was to make a device that was fully implantable. If the heart could be paced from inside, it would reduce the danger of infection and free the patient not just from the bed but from the hospital. In order to achieve full implantability, however, it would require a device that was extremely light and that employed a battery that was sufficiently small yet long-lasting. In addition, the electrical leads would have to be able to accommodate substantial current while being contained completely within the body and not harming any tissue. A number of techniques were tried. In 1958 engineer Rune Elmqvist and surgeon Åke Senning at the Karolinska University Hospital in Solna, outside Stockholm, developed a device using rechargeable batteries that could be implanted in a patient and charged externally with an induction coil. Although the device failed after only three hours, many historians consider the patient, Arne Larsson, to be the first human to have a fully implanted pacemaker. Over the next two years a series of trials eventually resulted in a patient living nine months. Medical engineering had passed another milestone, but a truly satisfactory implantable pacemaker was not yet available.
That availability occurred following clinical trials beginning on 15 April 1960 when William C. Chardack, a surgeon at the Veterans Administration hospital in Buffalo, New York, USA, assisted by Andrew Gage, implanted devices into the chest cavities of a series of ten patients with heart problems caused by failures of their hearts’ electrical systems. The inventor of the device, local engineer Wilson Greatbatch, had heard about Bakken’s work, and thought he could solve the battery problem. He eventually convinced Chardack to work with him. The device, for which Greatbatch obtained a patent in1962, used a two-transistor, transformer-coupled oscillating circuit powered by a mercury battery. The patients, who formerly would have died within weeks under any known treatment, lived for another eighteen months to thirty years. Since Earl Bakken already had in place the infrastructure to produce and distribute pacemakers, and because Chardack and Lillehei were friends, Greatbatch licensed his invention to Medtronic. Greatbatch continued to design and patent improvements in pacemakers for Medtronic until 1972. One of his last achievements was the development of a five-year lithium battery, which became the industry standard for use in pacemakers.
Since then, there have been significant continuous improvements in the pacemaker, especially in battery life, biologically neutral packaging, and computer control of the rate of pacing. Another key development has been the introduction of microprocessor-controlled devices. Beginning with Bakken’s model, the pace could be adjusted, but the heart had to be monitored separately. Modern pacemakers contain sensors and microprocessors that monitor the heart and adjust themselves appropriately. The technological advances in the fully implantable artificial pacemaker have been matched by expanding penetration into society.
By the end of the 20th century, more than 100,000 artificial pacemakers were being implanted annually worldwide. This significant technological achievement has resulted in millions of patients benefitting from an extended life span and an improved quality of life.
References of Historical Significance
References for Further Reading
About the Author(s)
Michael N. Geselowitz is Staff Director of the IEEE History Center. He holds S.B. degrees in electrical engineering and in the anthropology of technology from the Massachusetts Institute of Technology, and M.A. and Ph.D. degrees in the anthropology of technology from Harvard University. His research and publication focus has been on the history and social relations of technology, and he has held teaching and research positions relating to the social study of technology at M.I.T., Harvard, and Yale, including stints as Collections Manager/Curator at Harvard's Peabody Museum and Laboratory Director at MIT’s Center for Materials Research in Archaeology and Ethnology.