50th Anniversary of Defibrillation: Paul M. Zoll, MD and the Beginning of ZOLL Medical Corporation

My father Paul Zoll had a long and distinguished research career. A good summary is on the Heart Rhythm Society's website (https://www.hrsonline.org/ep-history/notable_figures/bios/paul_zoll/). His research was in the setting of an active private practice, and his practice was the source of his inspiration and incentive, as well as unending distractions. Every time he tried to do anything, he was constantly interrupted by clinical issues with various patients. He was totally committed to taking the best care of his patients, though. He was very demanding of the hospital staff and attentive to his patients. He presented a gruff demeanor as necessary, but it was totally an act. He had a wry wit. He was full clinical professor at Harvard Medical School at the Beth Israel Hospital. He continued this active research program with many collaborators. He was also the editor of Circulation for many years. As I was growing up, I was primarily aware of his introduction of the pacemaker in 1952 and the defibrillator in 1956. Many of the more medically-oriented contributions were beyond my understanding at the time. These two principal introductions of the pacemaker and defibrillator were in association with Electrodyne Company, which was headed by Alan Belgard and Norm Simon. Together, with the introduction of real-time cardiac monitoring, these inventions formed the basis of modern electrical rhythm therapy. At the time, this therapy was considered a radical innovation, and there was considerable opposition to the use of these devices on many fronts. Many felt that the resuscitation of people who were essentially dead was against God's will; this was until an editorial by a religious leader in Boston applauding the use of the device quieted that opposition. It also was difficult to sell the devices to hospitals since they required that all equipment had UL listing. The pacemaker could not get UL listing because you could get a shock from the device. These problems demonstrate how innovative these ideas were at the time. Surprisingly, my father was often very reluctant to try new therapies, such as new models of pacemakers or leads, on his patients until they had stood the test of time in other doctor's patients. He was not always so ready to trust others' innovations. The interests of his own patients came first. In 1976, after just finishing graduate school in physics, I was privileged to join my father's research team for a few years. Other principal actors in the collaboration were Alan Belgard from Electrodyne, the thoracic surgeon Howard Frank, and Matt Weintraub, a research fellow. We had a grant with RCA to attempt to selectively heat parts of the myocardium with microwave energy to increase rhythmicity. This project eventually went nowhere because of the technical difficulties of trying to apply energy at such a depth from the surface. However, the project was useful in bringing us together, and it underscored my father's interest in developing a more satisfactory method of emergency temporary pacing. His original technique from 1952 was completely effective, but it had problems and waned in popularity after the introduction of transvenous pacing. The original pacemaker was often extremely uncomfortable in conscious patients, and it interfered excessively with EKG monitoring. No new units were being manufactured nor were there any available at that time. He felt that abandoning his external pacemaker was inappropriate, as transvenous pacing took too long to establish in an emergency. He wanted to reintroduce the old technique or some other, more attractive alternative. At that time, we typically met two or three times per week in the basement of Yamen's Building of the Beth Israel Hospital or in the animal laboratory to do various experiments. These included mechanical pacing, epicardial electrodes, or defibrillation experiments in which we measured delivered current and voltage, and began to sort out variables involved in doing these measurements. We also conducted microwave and ultrasound heating experiments. In addition, we did clinical measurements of various parameters of pacing at the time of revisions of pacing systems, and we measured threshold and impedances in clinical cardioversions. In the setting of vast experience with the early application of electricity to cardiac rhythm coupled with a laboratory full of related documents and equipment we were in a good position to capitalize on any ideas that we might have. When we were a little discouraged with the lack of progress in the microwave heating or mechanical pacing experiments, Alan Belgard wrote on the top of our chalkboard Painless External Electric Pacing. We thought that should be a goal, but we had no idea how to achieve it until one day in 1979. Firstly, my father had the foresight to place importance on this goal, and indeed this was contrary to the opinion of many of his contemporaries. For example, we were unable to interest anybody in manufacturing his old device. When we did eventually form ZOLL Medical Corporation, we did market research, which indicated that there was no market for a non-invasive pacing device. Most cardiologists did not see any need for it. Transvenous pacing was generally considered an adequate solution. Secondly, Alan got a set of high-impedance electrodes intended for a TENS unit. We tried them and were amazed at how much current we could apply comfortably. Immediately we decided to see if we could apply this technology to pacing. Thirdly, I felt we could further take advantage of an optimum electrode size, and electrical waveform and duration. At the time, longer pacing pulses were thought to be dangerous, but the experiments had been relatively crude and without good control of waveforms. We investigated this issue again in animals and found no safety compromise. After we established an equivalent safety compared with the old device, we did most of the testing of the new technique on ourselves. Two important principles were applied: 1) We always had the defibrillator standing by just in case we were wrong about the safety; and 2) The person receiving the pacing pulses had control over the amplitude in accordance with the Geneva Convention against torture. We optimized the waveform and electrode size for greatest comfort and efficacy. We found the new combination of features much more satisfactory, compared with the original device. We now had a pacemaker that was usually quite comfortable for a reasonable period of time, and that was easy to use because the effectiveness was easily demonstrated on a cardiac monitor. Temporary emergency pacing was an old problem that had frustrated my father for many years. It was extremely gratifying to be able to help solve it. Together we applied for a patent. Initially, we applied for 510K marketing permission, that is, the grandfather-device permission. The FDA said that we would need clinical trials and pre-market approval. Initial conversations with existing pacemaker and monitor manufacturers yielded no interest. We felt we would need to form a company to do the trials and market the device. At the time, Leigh Stein was a patient of my father and an entrepreneur with his own manufacturing company. He was delighted to help with the formation of what was initially called Ross Research. He assembled a group of venture capitalists to fund the startup. It was interesting to sell the idea to businessmen; they commented that this was not the usual dog-and-pony show they saw from a startup company. It was not a polished presentation, but an actual demonstration of external pacing in our dingy basement laboratory. The device sold itself, and my father's record of accomplishment silenced any doubt. With assembly help from a small company called Biodesign, I built seven reasonable quality prototypes into existing monitors and wrote an investigational plan and a report of prior investigations to do clinical trials. While we were waiting for permission to begin clinical trials, the FDA suddenly reversed course and granted the 510K application. We then had patent protection, FDA clearance, and clinical prototypes with a total expenditure of way less than $100,000. In 1983, I planned to leave for an accelerated medical school program. We hired Rolf Stutz as the first chief executive and, subsequently, Lou Rom as the first marketing person. My father always edited the grammar on Lou's press releases, as he had edited Circulation. We established a manufacturing facility in Cambridge, Massachusetts. Rolf hired an electronic engineer, Koon Van Opijnen, and designed our pacemaker to fit into another OEM monitor. We were on the market and brought production devices to the American Heart Association meeting in Miami in 1984. We demonstrated pacing on salesmen in our booth to the astonishment of cardiologists attending the meeting. Cardiologists stood five deep or more around our display during demonstrations. Alan Greene, our second salesperson, was also there. There was also a spot on CBS News. We recorded over 600 registrations requesting additional information. ZOLL Medical Corporation went public in 1994. My father was on the board of directors almost until his death in 1999. Indeed, marketing surveys had shown there was no need for this technique. Acceptance was very slow and several inferior copies came on to the market. We suffered especially at first by not having an integrated defibrillator. However, our fortunes improved. I'm a little bit prejudiced, but I feel that the company does the required research and produces quality equipment...and that my father would approve.