Heart Surgery in New Zealand: The Dramatic Evolution of a Lifesaving Specialty (Part 2)

An Epidemic of Coronary Artery Disease | In the early 1970s in New Zealand, as in most western countries, the incidence of disability and death from disease of the coronary arteries reached a peak. We now know that this was related to many factors, including cigarette smoking, high consumption of saturated fats, high blood pressure and obesity with its associated lack of exercise and diabetes.

Many middle-aged people, mainly men, were unable to work with chest pains occurring with minor effort or worse, at rest; pain known as angina. Sudden deaths in relatively young people were common. That these problems were due to narrowings in the small coronary arteries which supply blood to the heart muscle had been shown years earlier by injections of contrast material, opaque to x-rays.

The operation is usually done with the heart arrested using a heart-lung machine, but more recently is sometimes done with a beating heart. Later improvements include use of superior grafts, the internal mammary artery, from the inside of the chest wall, or the radial artery from the forearm. The first such operation at Green Lane was performed by Sir Brian Barratt-Boyes in 1969.

The operation provided dramatic relief from angina, together with protection from death in some groups of patients. The grafts, especially the saphenous veins often developed late arteriosclerotic narrowing, but this has been reduced since the introduction of statin drugs which reduce blood cholesterol. Demand for the procedure grew exponentially and despite the more recent advent of angioplasty, it remains the major part of the workload of most adult cardiac surgical departments.

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Dilating Narrow Coronary Arteries | In 1977 Andreas Grüentzig in Zurich showed that it was possible to dilate a narrowed coronary artery by inflating a balloon on a double lumen cardiac catheter introduced through the femoral artery in the groin and positioned across the localised narrowing under x-ray control, a procedure named angioplasty. Cardiologist Tony Roche from Green Lane visited Grüentzig, and introduced the procedure to New Zealand. Angioplasty was much less painful, invasive and resource intensive than coronary artery surgery and was soon widely adopted.

However, it became apparent that after about six months the narrowing had recurred in about 30% of patients, due to scarring and elastic recoil. To prevent this, the balloon was covered with an expandable metal mesh, or stent, which remained in place when the balloon was deflated. This halved the incidence of late narrowing which has been further reduced by covering the stent with material containing drugs which inhibit scar formation. The catheters used have now also been improved and are now routinely inserted through the radial artery at the wrist.

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Check out Part 3 for the developments in transplants, and the future of cardiac surgery.