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.
Implanting the device is often considered a routine procedure for the growing population of patients who get them. In 1993, there were just over 121,000 pacemaker implantations in the United States, according to a 2012 study in the Journal of the American College of Cardiology. Last year, about 320,000 people got pacemakers, according to device-maker Medtronic—that's an increase of more than 60 percent over two decades.
More people getting pacemakers translates to more business for companies like Medtronic, which says it makes half of the world's pacemakers. But Calkins, the doctor at Hopkins, says requiring new pacemakers every 10 years isn't about protecting financial interests through planned obsolescence. The thing is: A decade is a really long time in medical years.
"And the reality is, every time your pacemaker runs out, you don't just replace the battery," Calkins told me. "You replace the whole pacemaker. You may say, 'This seems fairly wasteful. Why don't we just put in a new Duracell battery?' But there are always advances in pacemakers. The technology keeps getting better. They are smaller, they last longer, they have more of an ability to communicate with programmers."
In other words, pacemakers may seem outdated battery-wise, but they're actually heading in the same direction as most wearable gadgets: Data-driven and responsive to the behaviors of the person who is wearing—or in this case implanted with—the device.
Some pacemakers already have responsive capabilities. They can be set to recognize when a person's working out—so they'll automatically keep her heart beating at, say, 155 beats per minute while she jogs. "Pacemakers are just sort of a safety net, if you will," Calkins said. "[They set the rate] below which your heartrate can't go any slower, in case our own body's pacemaker's is starting to get sluggish."
Activity-specific heart-rate programming is standard with today's pacemakers. But Mike Hess, device president of research and development for the pacemaker division at Medtronic, says the pacemaker of the future will be even more sophisticated. Scientists are looking for more useful applications for the huge trove of data that pacemakers collect about people implanted with them. The idea is to figure out how that data—coupled with data from other monitors and devices—might contribute to more comprehensive understanding of a person's health.
"One area that a lot of people have interest in is how you integrate this implantable tech because these devices that are implanted have a unique front-row seat," Hess said. "How you link all of this data is a big area of focus for the future."
Hess says he can envision a person having a digital hub in her home—maybe an app or a website—where she could cross-reference various information being sent from devices like pacemakers, scales, blood pressure cuffs, etcetera. Data from different devices would be sent to and analyzed by a central system, then available for patients and their doctors to review.
Smart pacemakers have already raised some questions about security. Former Vice President Dick Cheney told 60 Minutes he had doctors disable the wireless capability on his pacemaker because he feared hackers could access it to carry out an assassination attempt, a worry device-makers said was justified.
Today, developers are also working on building pacemakers with anti-infective properties. Although the risk of infection is low, the more times someone has to have a pacemaker implanted, the more opportunities for infection there are.
Not surprisingly, each generation of pacemaker continues to shrink in size. One group of researchers announced this month that it built an implantable nano-ribbon strong enough to power a pacemaker.
And yet, for all the focus on building sleeker and smarter pacemakers, the notion of a rechargeable device has fallen out of fashion. Part of it has to do with the introduction of possible patient error.
"Rechargeable seemed like a good idea," Hess said. "But if you're putting a pacemaker in to keep someone alive, you don't want that to rely on their ability to recharge the pacemaker ... So the interest in rechargeables has really dropped off quite a bit as the battery technology and circuit technology is allowing devices to last more than 10 years."
That 10-year lifespan of a pacemaker can also be measured in about 420 million heartbeats, long enough that many patients and doctors are satisfied with switching out the device when the time comes. (If you live to be 80 years old, it's reasonable to expect about 3 billion heartbeats over the course of your life.)
Again, Calkins: "If you look at where we're going, we certainly are not going in the direction of rechargeable pacemakers … Physicians and patients don’t want it because they wouldn't get the latest technologies. I never would expect another rechargeable pacemaker to be produced."