Biography of Paul M. Zoll

1911–1999

Paul M. Zoll was born and educated in Boston. He attended Harvard Medical School and trained and practiced at the Beth Israel Hospital in Boston for the remainder of his career. During the Second World War, he and Dwight Harken described the operative removal of foreign bodies, shrapnel, bullets, and other metallic objects from within and about the heart and great vessels. These publications demonstrated the ability to successfully operate on the heart, an intervention that had previously been done infrequently.

In 1950, a presentation at a meeting of the American College of Surgeons, in Boston, about stimulating the sino-atrial node via a transvenous catheter, inspired Zoll to develop a technique for pacing the heart through the intact chest during asystole. With an epochal publication in 1952 he described cardiac resuscitation via electrodes on the bare chest with 2-millisecond duration pulses of 100–150 volts across the chest, at 60 stimuli per minute. This initial clinical description launched widespread evaluation of pacing and the recognition by the medical profession and the public that the asystolic heart could be stimulated to beat; it became the basis for future clinical pacing developments. This technique eventually fell from favor, except in an emergency, because of associated pain and the limited mobility it allowed the patient. It was later revised using larger skin electrodes and longer pulse durations, both of which made the shocks less painful and therefore more acceptable.

In 1955, Zoll described a mechanical technique for "stimulating" the asystolic heart. In 1956, he published a transcutaneous approach to terminate ventricular fibrillation with a much larger shock, of up to 750 volts, and later described similar termination of ventricular tachycardia. His use of an alternating current shock began clinical cardioversion–defibrillation but eventually was replaced by direct current shock, largely for technical reasons.

He eventually became an advocate of patient monitoring in the coronary care unit during periods of increased vulnerability. The first such monitoring facilities used equipment manufactured by the Electrodyne Company, with which he had been long associated. He was briefly involved in the development of a pacemaker to be implanted by thoracotomy, but he and Electrodyne soon ceased its manufacture. He participated in the development of emergency pacing and defibrillation throughout his lifetime, but did not participate in the later development of implantable cardiac pacing or implantable cardioversion–defibrillation, both of which benefited from his repetitive pioneering efforts.

Zoll was a practicing physician throughout his life with a reputation for careful and dedicated attention to his patients, many of whom he served for decades, all simultaneous with his groundbreaking research in bradycardia and tachycardia control. He was awarded the Lasker Award in 1973 and recognized as a Pioneer in Cardiac Pacing by the North American Society of Pacing and Electrophysiology (NASPE) in 1989.

In 1980, Zoll cofounded ZOLL Medical. His seminal work in electrophysiology, internal and external defibrillation, cardioversion, and external pacing provided the foundation for the company. More than 30 years later, the company culture remains focused on new technology and improvements in care provided by that technology in the tradition of the company’s namesake.