The human heart is the ultimate timepiece. And yet it's not always the most reliable one. So an estimated one million people per year get back-up systems, pacemakers, implanted to restore the heart's rhythm when it falters. If you don’t have a pacemaker, it’s likely you know someone who does.
The procedure is common but invasive. Doctors make an incision in the patient’s chest, and guide a wire through the vein and into the heart. The device at the other end of the wire is secured under a flap of skin created from the incision. It's common for patients to spend a night in the hospital after getting a pacemaker implantation, which is overwhelmingly considered safe. There are very few deaths attributable to pacemaker implantation.
Most of the patients who get pacemakers are older than 60, but since pacemakers usually don't last much longer than a decade, plenty of people find they outlive their devices and have to get new ones implanted.
Why should they have to?
We have rechargeable batteries for all kinds of devices these days—smartphones, laptops, flashlights, drills, vacuum cleaners, portable speakers, etcetera, etcetera—so why not find a way to recharge the device that's arguably the most essential one a person can have?
"The answer to that question is that we used to have them," said Hugh Calkins, a professor of medicine and director of the Arrhythmia Service at Johns Hopkins Hospital. "There were rechargeable pacemakers back in the '70s, and they got rid of them. If you're cynical, you say it's because the companies then couldn't sell a new pacemaker every 5 to 12 years."
But it's not that simple, Calkins says. More on that in a minute. First, a look at the device itself. There are a few different kinds of pacemakers but here's the basic gist: A pacemaker consists of battery-powered computerized generator that's usually about the size of a matchbook and is connected to the heart with wires.
The wires are tipped with sensors that monitor the heart's electrical activity, transferring data back to the generator. If that data reflects an abnormal heart rhythm, the generator sends electrical pulses through the wires to get your heart lub-dubbing properly again.
The whole thing is implanted in your chest: Wires are attached to the heart, but the generator is implanted just below the surface of the skin, usually pretty high up on one side of your chest.
Pacemakers have come a long way since their early development about a century ago. Cardiologists in the 1930s designed portable hand-crank generators that were hooked up to current-interrupting devices that would deliver electric current to the heart via—brace yourself for this—a really long needle, according to a 2010 paper about the history of the device. But it would be decades before surgeons in the United States successfully implanted a pacemaker in a human patient.
That happened June 6, 1960, in Buffalo, New York. The patient, a 77-year-old man, lived for another year and a half as a result of the device. (A patient in Sweden had a pacemaker implanted in 1958, but the device failed after three hours. That patient subsequently had to have 21 separate pacemaker implantations.)
In the early days, pacemakers were bigger—about the size of a pack of cigarettes in 1960—and the procedure was riskier. Even as implantation became more common, the devices also had a shorter lifespan, lasting only about a year or two.
Reliable batteries were such an issue in the early days that scientists obsessed over ways to make them last longer, including working to develop rechargeable pacemaker batteries. The same team that carried out the first successful implantation in the United States developed a plutonium-powered pacemaker that would last for 30 years. But nuclear-powered pacemakers were impractical. Plutonium is toxic, and disposal of nuclear devices would have been a huge issue.
Often when researchers worked on making rechargeable pacemakers in the 1970s, they did so with children in mind. Although the vast majority of pacemaker recipients are older than 60, there is a small population of much younger patients outfitted with pacemakers. In 1965, scientists developed a rechargeable pacemaker that could last up to three months without being charged, according to a paper in the Annals of Thoracic Surgery from that year.
Even today, a baby born with congenital heart disease might need a pacemaker early on, and would have to get a new one implanted again and again over the course of his life.
These days, pacemakers last anywhere from about five to 12 years using lithium-iodine cell batteries.