Arnold Schwarzenegger just got a pacemaker. Here's what to know about the heart device that makes him 'a little bit more of a machine.'

Arnold Schwarzenegger has become more like his iconic Terminator character after having surgery last week to receive a pacemaker, the 76-year-old actor and former California governor announced Monday. “I had surgery to become a little bit more of a machine. I got a pacemaker,” he told listeners to his podcast, Arnold’s Pump Club. Schwarzenegger was born with a bicuspid aortic valve, a heart defect that can eventually lead blood to flow the wrong direction and weaken cardiac function. He previously had three open heart surgeries to treat the congenital condition, and said he’s doing great since having the pacemaker placed.

Here’s what you need to know about pacemakers and when someone may need the device.

What is a pacemaker?

A pacemaker is a small, battery-powered device that controls the heartbeat. Our heartbeats are controlled by a highly efficient, biological electrical system that ensures our heart steadily pumps blood to the rest of the body. But sometimes — due to age, illness, chronic health conditions or problems such as heart attacks and heart failure — this electrical system goes haywire. If it goes on for too long, the reduced or irregular blood flow can harm the heart, brain and other organs, according to the National Institutes of Health. “The idea behind the pacemaker is to help stimulate the heart in a more regular rhythm,” Dr. Sadiya Khan, a professor of cardiovascular epidemiology at Northwestern Feinberg School of Medicine, tells Yahoo Life.

The device consists of two primary components: a box containing a battery and a tiny computer that processes information and delivers electrical impulses and wires (called “leads”). The wires are threaded into the veins around the heart. Electrodes at the ends of these wires perform dual functions: They sense your heartbeat, reading when it slows (or, less commonly, speeds up) to an abnormal space, and deliver electrical impulses that prompt the heart to beat, getting its rhythm back on track.

Information from the electrodes is processed by the computer in the pacemaker box, which is surgically implanted on the left side of the chest, just under the collarbone. The computer determines when the heart needs a jolt to get back on rhythm and delivers the electrical impulses back through the wires to the electrode, stimulating the heart muscle to contract.

Pacemakers are also sometimes used temporarily when someone is recovering from a heart attack or heart surgery, but in this case only the wires are inserted into the body; the pacemaker box stays outside the body, and the device is generally only used for a few days.

When does someone need a pacemaker?

The device is most commonly implanted when someone’s heart beats too slowly or is too weak. They’re often used in patients who have an arrhythmia condition called atrial fibrillation, but can also be used in those who have had a heart attack or heart failure or are at risk of going into cardiac arrest.

Pacemakers are also sometimes used to regulate the heartbeats in people with congenital heart disease, a group of conditions that affect about 1% of people born in the U.S., according to the Centers for Disease Control and Prevention. Schwarzenegger has one of these conditions, called a bicuspid aortic valve, which can cause blood to flow the wrong direction and overwork the heart by trying to push blood through the narrower passageway.

Schwarzenegger previously had open-heart surgeries to replace a defective aortic valve and another heart valve. Each of those have to be replaced after an average of 12 to 15 years, and he had those valves replaced again in 2018 and 2020. The actor didn’t reveal the precise reason he had a pacemaker placed, but he did mention his heart defect.

What is life with a pacemaker like?

Most people can return to normal activities after recovering from surgery. In fact, the American Heart Association recommends being physically active to maintain health and good blood circulation, as long as patients don’t overdo it. People with pacemakers can travel by plane, car or train, but should tell security checkpoint workers about their pacemakers because they may need to be screened differently. The only major concerns for those with pacemakers are strong magnets and electrical fields, which can disrupt the device.

Otherwise, the device should be basically unnoticeable, says Khan. “You shouldn’t feel anything when the pacemaker is working,” she tells Yahoo Life. She adds that some patients are aware of the pacemaker box and battery, which can sometimes be seen or felt under the skin, but it shouldn’t be evident when the device is delivering electrical impulses or not.

How long do pacemakers last?

A pacemaker’s battery typically lasts between five and seven years before it needs to be changed, according to Johns Hopkins Medicine. Sometimes the entire pacemaker box, including the battery, is replaced. Other times, just the battery is swapped out. The procedure is fairly simple, and can be sometimes done as an outpatient procedure.

How long someone will live after getting a pacemaker “really depends on why they needed the pacemaker,” says Khan. “The pacemaker itself should not influence how somebody feels or how they’re doing; in fact they should feel better, if they were having problems beforehand.” Patients who have fewer or less severe health issues may have a nearly normal life expectancy with a pacemaker, according to the Cleveland Clinic.

As for Schwarzenegger, he’s barely missed a beat. “I had my surgery on Monday, and by Friday, I was already at a big environmental event with my friend and fellow fitness crusader Jane Fonda,” he said on his podcast.