Hypothermia in Open Heart Surgery

Researcher name: 
W.G. Bigelow, OC, MD, FRCSC*

Until the advent of heart surgery, there was virtually no special treatment for the vast number of people suffering and dying from heart failure. Surgeons were fearful of operating upon the heart.

Heart disease is the most common cause of illness and death – a greater threat than cancer. Until the advent of heart surgery, there was virtually no special treatment for the vast number of people suffering and dying from heart failure. Surgeons were fearful of operating upon the heart.

In the 1940s surgeons exposed the heart in order to correct congenital deformities of the nearby blood vessels. It did not stop, thus surgeons lost some of their fears. But the surgeons would never be able to correct or cure heart conditions unless they were able to stop the circulation through the heart, open it, and operate in a bloodless field under direct vision. How to do this?

Probably as a result of previous research on frostbite, I woke one night with a simple solution: "Cool the whole body (hypothermia), reduce the oxygen requirements, stop the circulation, and open the heart." (Hypothermia – low body temperature).

This was a virgin field of physiology and blood chemistry at low body temperature that had never been studied. There were great hurdles. Allowing the body temperature to fall was considered highly dangerous and it was believed that hypothermia actually increased the oxygen requirements causing shock and death. For these reasons, no one had ever thought of using low body temperature for heart surgery. There were no articles in the world literature.

In spite of these beliefs, our surgical research team from the Toronto General Hospital commenced the study of hypothermia in 1946 at the Banting Institute, working with experts from four other university departments. For 10 of the 18 years of research a groundhog farm was established in Collingwood (the only colony in the world) – a major effort to learn the secret of safe cooling from hibernation. Twenty brilliant surgical research fellows contributed to this study.

In 1950, after four years of research, our Toronto team reported to medical science the first successful open heart operation on record. Using hypothermia and animals, the body temperature was lowered, the blood entering the heart was stopped and the heart was opened for 20 minutes. Following this report to a senior American society, hypothermia became a sensation and dominated the surgical scientific literature for 10 years.

In 1954, after further research, the first open heart operation on a human patient in Canada was carried out by our team at the Toronto General Hospital, using hypothermia. Hypothermia became the most common form of open heart surgery between 1954 and 1960 in the few cardiac surgery centres that existed around the world.

The heart-lung pump was also under study by John Gibbon in the 1940s in Philadelphia. The first successful open heart operation on a humans using the heart-lung pump, was carried out a year after the first hypothermia procedure. By 1960, it was safe enough to combine both techniques – the "pump" and "hypothermia" – by having the blood flow through a cooling device as it passed along the plastic tube back to the patient. This is called cardiac bypass for open heart surgery, as we know it today.

The story of the worldwide development of open heart surgery in the last four decades is a saga unparalleled in medical history. At present, every known heart condition can be treated and if the disease has progressed to its terminal stages, a heart transplant is possible – all with an acceptable low risk. This great advance, as usual, was only possible using experimental animal research. Most of the hypothermia research was with small animals. In the final stage of testing, larger animal species were used.

The announcement of a discovery in medicine is very often followed by controversy and priority claims from other unheralded investigators, (e.g. insulin). They come out of the woodwork. No one in the world has ever questioned our Canadian priority in: (1) demonstrating for the first time the true relationship between metabolism (oxygen requirements) and body temperature and (2) showing the use of hypothermia for the first open heart surgery.

Hypothermia is an integral part of present-day cardiac bypass surgery. In North America, in one year, nearly one million open heart operations have treated coronary and valvular disease and complicated congenital heart defects. In 1991, in Toronto alone, there were 4,000 such operations. The cardiac bypass technique is used in neurosurgery, lung transplantation, and several important operations involving the major arteries (e.g. aorta).

Over the years, the team received necessary funding by grants from the Defence Research Board, Medical Research Council of Canada, National Research Council, Federal Department of Health, Bickell Foundation, and many private donors, notably Gordon M. Graham, Marian Webster Taylor, John W. Connell, John M. McFadyen and John T. Frame. In later years, major support was received from the Ontario Heart Foundation. Today, there is unfortunately a close relationship between financial resources and excellence of research, with the need for expensive high-tech equipment and specialized technicians.

*Deceased March 27, 2005