Academic Reading — Test 86

Reading passage

The human heart depends on a delicate electrical system to keep its chambers contracting in a regular sequence. When that system falters, the heart may beat too slowly or skip beats altogether, a condition that can leave a patient dizzy, breathless or, in severe cases, unconscious. For centuries physicians could do little but watch. The idea that an artificial electrical impulse might take over the work of a failing heart had been discussed since the nineteenth century, but it was only in the twentieth century that engineers and doctors built devices capable of delivering such impulses safely and reliably. The story of the pacemaker is therefore a story of collaboration between medicine and engineering, and it is one in which Australian and Canadian contributors played a central part. An important early step came in the late 1920s in Sydney, where an anaesthetist named Mark Lidwill, working with the physicist Edgar Booth, devised an apparatus that could deliver a controlled electrical pulse to the heart. The machine was powered from the mains electricity supply and used a needle inserted into the chamber of the heart. In 1928 it was reportedly used to revive an infant whose heart had stopped, and the child recovered fully. Lidwill, however, was reluctant to publicise the achievement, partly because of unease about the ethical questions such interventions raised. As a result, his work received little attention at the time and was largely forgotten for decades. Around the same period, an American physiologist, Albert Hyman, independently built a hand-cranked device that he called an "artificial pacemaker", coining the term that would later become standard. These first machines were bulky, were plugged into the wall, and delivered their current through the skin or through wires passed directly into the body. They could not be carried by a patient and, because they relied on the mains, a power cut could be fatal. The decisive shift towards a portable device occurred in Canada in the early 1950s. The engineer John Hopps, working at the National Research Council, collaborated with the surgeons Wilfred Bigelow and John Callaghan, who were investigating how cooling the body might assist heart operations. They observed that a chilled heart which had stopped could be restarted by an electrical stimulus, and Hopps was asked to construct a device to deliver that stimulus. The result, completed in 1950, was the first substantial Canadian pacemaker. It was still too large to implant and was driven by vacuum-tube technology, but it established that a manufactured device could pace a heart in a controlled and repeatable way. Hopps is often remembered in his own country as the father of the pacemaker, and he himself later received an implanted device. The remaining obstacle was size and power. A pacemaker tethered to a wall socket left the patient confined to a hospital and vulnerable to interruptions in supply. The arrival of the transistor changed everything, because it allowed circuits to be made small enough to be worn or, eventually, placed inside the body. Across the world, teams raced to produce a wearable and then an implantable unit. The first fully implantable pacemaker was placed in a patient in Sweden in 1958, and although that early model failed within hours, the principle had been proven. From that point the device evolved rapidly, with longer-lasting batteries, sealed casings to keep out body fluids, and circuits that could sense the heart's own activity and fire only when needed. Australia returned to the narrative through refinement rather than first invention. From the 1960s onwards, biomedical engineers in Australia worked on improving the reliability and intelligence of implanted devices. They contributed to the development of pacemakers that could adjust their rate in response to a patient's level of physical activity, so that the heart would beat faster during exercise and more slowly at rest, mimicking a healthy organ. Australian work on lithium batteries and on the long-term behaviour of implanted electronics helped to extend the working life of a pacemaker from a year or two to a decade or more, sparing patients repeated operations. These were not headline-grabbing breakthroughs of the kind that announce a new machine to the world, but they were the patient, incremental improvements that turned a fragile experimental object into a dependable medical tool. By the end of the twentieth century the pacemaker had become one of the most successful pieces of implanted technology ever made, restoring an ordinary life to millions of people whose hearts could no longer keep their own time. Its history shows how progress in medicine rarely belongs to a single inventor or a single country. An Australian beginning that was almost lost, a Canadian device that proved the concept could be engineered, a Swedish first implant, and decades of Australian refinement together produced a small object that quietly keeps a steady beat inside the chest of its wearer.