Heart Surgery in New Zealand: The Dramatic Evolution of a Lifesaving Specialty (Part 1)
On 3 September 1958 a large ventricular septal defect (hole between the two pumping chambers of the heart) was closed using a heart-lung machine, at Green Lane Hospital in Auckland. This was the first “open heart” operation performed in New Zealand. A lot of work went into getting to this point.
Pioneering Days | In the nineteen century the heart was regarded by many as sacrosanct and even as the “seat of the soul.” Eminent Viennese surgeon Theodor Billroth pontificated as late as 1884 that “any surgeon who dares to suture the human heart deserves to lose the respect of his peers”. This taboo was broken barely a decade later when, in Frankfurt in 1896, Ludwig Rehn successfully closed a stab wound in the heart of a young man who had been stabbed in a barroom brawl.
Subsequent progress was slow. The development of positive pressure ventilation during anaesthesia allowed safe surgery inside the chest, but thoracic surgeons were then preoccupied by the demands of tuberculosis. It was not until 1938 that Robert Gross in Boston successfully tied a patent ductus arteriosus, the channel between the aorta and pulmonary artery which normally closes soon after birth.
Following the Second World War operations were developed which could be performed without opening the heart. Mitral valves narrowed by the aftereffects of rheumatic heart were opened by a blind technique in thousands of patients. Surgeon Alfred Blalock and his cardiologist colleague Helen Taussig devised a palliative operation for “blue babies” who had the common combination of congenital defects known as tetralogy of Fallot. Their procedure increased blood flow to the lungs, with an apparently miraculous conversion of the children to a normal “pink” colour.
At this point, there was still no way to stop the circulation for long enough to correct the many common defects inside the heart. Stopping the heart requires a pump to circulate the blood, and some form of oxygenator to substitute for the exchange of oxygen and carbon dioxide in the lungs; i.e. a pump oxygenator or heart-lung machine. Suitable pumps were easily found, but oxygenators proved a major obstacle.
In 1954 outcomes in 18 patients were reported, using various devices ranging from monkey lungs, the patient’s own lungs and different mechanical contraptions. There was only one survivor, a young woman patient of John Gibbon in Philadelphia, who had worked on the problem for 20 years in his laboratory. His next three patients died, and, disheartened, he passed his machine on to the Mayo Clinic where a young surgeon, John Kirklin assembled a team of engineers, physiologists, anaesthetists and cardiologists to perfect the machine and introduce it into safe routine clinical use. This was the start of a new era, and it was with Kirklin that the young Brian Barratt-Boyes developed his skills.
First Steps in New Zealand | Following the success with Helen Arnold, surgery at Green Lane became routine, with, initially, two operations weekly. Fresh blood from six donors was needed to prime the machine, the oxygenator of which consisted of stainless-steel discs rotating on a spindle through blood within a Perspex cylinder. Gas exchange took place by direct contact of oxygen with blood on the surface of the discs. This inevitably gradually damaged the red cells of the blood, leading to temporary damage to other organs. The Texas surgeon Denton Cooley, famed for his speed, proclaimed that the moment the patients were put on the machine they started to die! Nevertheless, this technology, or its modifications, was used with outstanding success on hundreds of patients over the following fifteen years, at first mainly for correction of congenital defects, but later for valvular heart diseases, including homograft aortic valve replacement, which was pioneered by Barratt-Boyes at Green Lane in 1962.
Repairing Babies' Hearts | Approximately one in every hundred babies born have a congenital heart defect, and almost half die or become inoperable in the first year of life. In 1969 the mortality of babies having surgery with the perfusion techniques then available was prohibitive. Two junior doctors from Osaka in Japan told the Green Lane team of successful surgery in these infants in their hospital, using hypothermia.
When an anaesthetised baby is cooled with ice to below 28 degrees Celsius the heart ceases beating. The Japanese had been then cooling the babies to 18degrees using the heat exchanger on the heart-lung machine. At that temperature brain metabolism is minimal, and circulation could be stopped for up to 45minutes without brain injury. This permitted even complex intra cardiac defects to be corrected in an empty heart. Circulation with the heart-lung machine was then resumed, rewarming to 37 degrees.
The reduced perfusion time minimised blood and tissue damage and allowed consistent survival. The Green Lane group modified and publicised this method which was soon widely adopted. Ten years later membrane oxygenators, in which the blood is separated from the oxygen by a fine silicone or polypropylene membrane, came into general use. These need much less blood to prime and has largely obviated the necessity of this rather cumbersome procedure, though it is still useful in some circumstances.
Check out Part 2 for the developments in coronary artery disease treatment.