Obituary: Dr Paul Zoll

PAUL ZOLL made decisive contributions to treatment of life- threatening cardiac arrhythmias by the invention and successful application in humans of the cardiac pacemaker, cardiac defibrillator, and cardiac monitoring in the 1950s. His discoveries saved and improved the lives of millions of people throughout the world.

He was born in 1911 in Boston, Massachusetts. He received a bachelor of arts degree from Harvard College in 1932 and an MD from Harvard Medical School in 1936. His residency training was at Beth Israel Hospital in Boston and Bellevue Hospital in New York City. In 1939, he returned to Beth Israel Hospital as a research fellow in cardiology.

Initially, he worked under Dr Monroe Schlesinger and Dr Herrman Blumgart on the pathology of coronary arteries by injecting dye into the post-mortem human heart. He studied the relationship between the blockage of the coronary artery and chest pain and heart attack. This study was the forerunner of the modern-day coronary angiography and served as an important foundation of the pathogenesis of atherosclerotic ischaemic heart disease.

During the Second World War, Zoll served as an Army Medical Officer in the UK. There, he witnessed Dr Dwight Harken, his classmate at Harvard, remove foreign bodies (such as shell fragments) from around the heart. Zoll was impressed that the heart was highly excitable: whenever Harken touched the heart with forceps, it generated an extra beat.

In 1949, Zoll cared for a patient in her sixties who had recurrent fainting spells due to her heart intermittently being arrested. The patient died three weeks later and this greatly frustrated Zoll. He thought she would not have died if he had a way to stimulate the heart. Recalling his observation in the UK, he started to perform laboratory experiments to explore methods to pace the heart without opening the chest. This led to a successful electrical pacing of the human heart through the chest, saving the life of a patient in 1952. Following this, a number of groups in the world raced to develop a permanent implantable pacemaker - Zoll's group was among the first to apply it in 1960 to patients.

While the pacemaker was life- saving for cardiac standstill or slow rhythm, it was not effective for another kind of cardiac arrest - ventricular fibrillation (chaotic heart rhythm, commonly seen after a heart attack or severe heart failure). In 1956, Zoll was the first successfully to perform external cardiac defibrillation - the application of electric countershock to stop the chaotic rhythm. Cardiac defibrillators are now equipped in every hospital, ambulance, and even in commercial airlines, as it is the most rapid and effective procedure to terminate this lethal rhythm. Zoll also found that the cardiac defibrillation was effective in terminating most cases of life-threatening rapid heart rate.

Another important invention Zoll made during this time was the development of continuous cardiac monitoring with an oscilloscope with audio alarms. This allowed an immediate detection of irregular heart rhythm and patients could be treated without delay. The cardiac monitor is now standard in every coronary care unit, in intensive care units, operating rooms, and recovery rooms. Remarkably, Zoll did not patent any of his revolutionary inventions in medical technology. This allowed rapid dissemination of the technology throughout the world without patent restrictions and, therefore, contributed to saving millions of lives.

Zoll was head of the Cardiac Clinic at Beth Israel Hospital from 1947 to 1958. He was Associate Editor of Circulation, the official journal of the American Heart Association, from 1956 to 1965. He became a Clinical Professor of Medicine at Harvard Medical School in 1965. He maintained active clinical practice up until the early 1990s and continued to perform research on the external cardiac pacemaker. In the 1980s, Zoll and his son founded Zoll Medical Corporation, based on new, painless external electrodes Zoll developed in the later years.

Zoll was quite extraodinary in that he pioneered three critical areas of modern therapeutic electrophysiology: the cardiac pacemaker, the cardiac defibrillator, and the continuous cardiac monitor, enabling immediate diagnosis and treatment of potentially fatal cardiac arrhythmias. Any one of these would have been quite an accomplishment for a professor of cardiology. Furthermore, his concept laid the foundation for the development of highly sophisticated devices, such as anti-tachycardia pacemakers and implantable cardiac defibrillators.

In 1973, he received the prestigious Albert Lasker Award - many of those awarded this honour go on to receive a Nobel Prize in medicine or physiology. Indeed, given the impact of Zoll's work, he would have been a well-deserved recipient of the Nobel Prize. Nevertheless, his name will always be remembered because the cardiac pacemaker, cardiac defibrillator, and cardiac monitor will stay forever as the most important armamentarium of cardiologists. Ordered electrical activity is inherently fundamental for the heart and it was Paul Zoll who first taught us that electricity can (and should) be used to treat fatal cardiac arrhythmias in humans.

Seigo Izumo

Paul Maurice Zoll, cardiologist: born Boston, Massachusetts 15 July 1911; assistant in medicine, Beth Israel Hospital, Boston 1939-54, Head of Cardiac Clinic 1947-58, Physician 1954-93 (Honorary Senior Physician 1993); Research Fellow, Harvard Medical School 1941-65, Clinical Professor of Medicine 1965-93 (Emeritus); married 1939 Janet Jones (deceased; one son, one daughter), 1981 Ann Blumgart Gurewich; died Newton, Massachusetts 5 January 1999.