1923-2004 Biography
Born in Hamilton, Ontario, John Callaghan graduated from the University of Toronto Faculty of Medicine in 1946. After internship at the Toronto General Hospital he entered the "Gallie Course," the Post-Graduate Training Program in Surgery in Toronto. He was assigned as a Research Fellow to work with Dr. Wilfred (Bill) G. Bigelow at the Banting Institute of the University of Toronto.
Bill Bigelow had been overseas with the Canadian Army Medical Corps and had been interested in the effects of cold, particularly vascular injuries due to frostbite. Due to the dramatic achievements of the emerging field of heart surgery he spent time with Alfred Blalock at the Johns Hopkins Hospital and returned to Toronto to pursue clinical research that might facilitate safe interventions on the heart. Bigelow and Greenwood published their seminal work on the progressive reduction of oxygen consumption with increasing depths of induced hypothermia, suggesting the heart could be stopped to permit direct repair. Callaghan recalled that he had already been exposed to cold as a Medical Officer serving Inuit and Aboriginal Canadians in the Arctic, as well as experiencing a most memorable plane crash.
Callaghan and Bigelow were frustrated at their inability to revive hypothermic dogs from cold-induced ventricular fibrillation or arrest, and set about to determine the means to facilitate rewarming and resuscitation in order to obtain consistent survival. They attempted electrophrenic artificial respiration and radiofrequency rewarming, to no avail. Since the hypothermic canine model was beset by so many physiologic variables, Callaghan attempted to increase heart rate in normothermic animals subjected to vagal arrest or sinus node crush. The results were inconsistent but ultimately he was able to increase or decrease heart rate using a transvenous electrode connected to an "artificial pacemaker."
His research efforts were recognized by the University of Toronto which awarded him the Reeve Prize in Surgical Research (1949) and the Lister Prize in Surgery (1950).
The external pacing device, constructed with the engineering assistance of J.A.(Jack) Hopps of the National Research Council in Ottawa, delivered electrical impulses via a transvenous wire/electrode to the region of the sino-atrial node, Their results were presented in Boston at a meeting of the American College of Surgeons and later published in Annals of Surgery in 1950. Local media attention to their presentation prompted Paul Zoll to write requesting the circuitry. Working with M.I.T., Zoll developed and popularized his own version of an external pacemaker. Bigelow, Callaghan and Hopps, however, are generally given credit for the original idea and potential application. Of interest, Bigelow and Hopps in later life each received permanent implanted pacemakers.
John Callaghan is an outgoing, likeable man who is a born raconteur and delights in telling of the difficulties of achieving reliable cardiac stimulation through the electrode positioned "somewhere near the sinus node" in both the experimental hypothermic animal and in some desperate clinical settings of cardiogenic shock in thoracic surgical patients of Prof. Janes (1949). He continues to bemoan his failure to advance the catheter "another two inches" through the tricuspid valve to obtain right ventricular stimulation for patients with heart block.
His clinical training was at the dawn of heart surgery pioneered in Toronto by his mentors, W.G. Bigelow and W.T.(Bill) Mustard at the Hospital for Sick Children. He later worked with Lord Russell Brock in London and Frank Gerbode in San Francisco. He was appointed Professor of Surgery and Director of Thoracic and Cardiovascular Surgery at the University of Alberta in Edmonton, a position he held from 1960 to 1986. Dr. Callaghan maintained an active research interest throughout his long and distinguished career, with particular interests in heart valves, extracorporeal circulation, myocardial preservation and coronary bypass conduits.
The government of Alberta recognized his contributions with the Achievement Award for Excellence in Medical Research in 1982 and the Order of Excellence in 1986. He received a Distinguished Scientist Award from NASPE in 1985 and was made an Officer of the Order of Canada in 1986.
- Bernard. S. Goldman, MD, FRCSC
March 26, 2002
Toronto, Canada
