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What Is a Pacemaker?

Contributor Nathaniel Steiger, MD
9 minute read
A pacemaker in the palm of a hand

The heart is like an orchestra: If one musician starts playing too fast or too slow, it can throw off the whole song.

“The heart is an organ that pumps in a coordinated manner using an electrical signal. Sometimes that electrical signal can have issues. It can lead to fast heart rates, or it can lead to very slow heart rates,” says Nathaniel Steiger, MD, a Mass General Brigham electrophysiologist. Dr. Steiger cares for patients at Brigham and Women’s Hospital. Electrophysiologists are cardiologists who specialize in treating abnormal heart rhythms, called arrhythmias.

For certain arrhythmias, a device called a pacemaker helps all the instruments play on the beat. Learn how pacemakers work, find out how doctors implant a pacemaker, and how to minimize risks of complications. 

Electric signals and heart function

The heart has four chambers that pump in a coordinated way to send blood to the rest of the body. The top two chambers, or atria, pump first. Then the bottom chambers, or ventricles, pump second. “They’re coordinated by a pacemaker we’re born with, called the sinus node. It’s a bundle of cells that signals the heart to pump. It sends signals across specialized muscle cells that conduct electricity quickly,” says Dr. Steiger. As the electrical signals move through the heart chambers, they contract in an organized way.

Disease in the sinus node, or in the special muscle cells that conduct electricity, can lead to slow heart rates, known as bradycardia. Bradycardia may lead to symptoms of fatigue, shortness of breath, and chest pressure. In more severe cases, people can experience lightheadedness and sudden fainting.

People who have bradycardia might need a pacemaker depending on the severity and the underlying cause. Another group of patients who may require a pacemaker are those who require medications to treat fast heart rhythms, known as tachycardias, which result in reducing an otherwise normal heart rate to one that is too slow.

“In order to adequately treat the fast heart rates with medicines, they need a pacemaker to support their lower heart rate. This may affect people with Afib (atrial fibrillation),” Dr. Steiger says. Patients who have certain types of heart failure may also benefit from a pacemaker.

Pacemakers have sensors that listen for a heartbeat. “If it doesn’t hear one within a certain period of time, it’ll generate its own through an electrical signal,” explains Dr. Steiger. Pacemakers also have accelerometers and other sensors, which sense movement. The pacemaker adjusts the heartbeat based on activity levels, whether someone is exercising or sleeping. 

Types of pacemakers

Different types of pacemakers include:

  • Transvenous pacemakers are implanted with one, two, or three leads (or wires), depending on the cause of bradycardia and underlying heart function. The tip of the lead is implanted inside the heart via veins in the chest, and the other end of the lead is attached to the pacemaker generator, which is traditionally implanted in the left upper chest over the breast muscle. “Usually people get two wires, a wire in the top chamber and the bottom chamber,” says Dr. Steiger.
  • Leadless pacemakers are a newer option, which are the size of a small paperclip and are implanted directly into the heart muscle. There are no leads, which lowers the risk of infection. They don’t work for all bradycardias but may be a good option for some patients.

Electrophysiologists can also use pacemakers to provide physiologic pacing. “We can pace the heart in a similar way to your biological pacemaker to help prevent problems with heart failure in the future. It’s a newer, advanced technique that Mass General Brigham doctors are really focusing on in certain patients,” explains Dr. Steiger. 

Pacemaker surgery

“We consider implanting a pacemaker to be a minimally invasive procedure. Usually patients come in the morning, and they go home later that day,” Dr. Steiger says. Patients are given a local anesthetic and put under conscious sedation, where they’re partially awake without feeling discomfort or pain.

During the procedure, the doctors make a small incision in the upper chest next to the shoulder. They find a vein and advance the pacemaker wires through the vein into the heart using x-ray guidance. Sometimes they use intravenous (IV) contrast to help identify heart structures.

“We attach the wires to the heart muscle by deploying a little screw at the tip of the wire. Next, we attach the other end of the wire to the pacemaker device, which we implant under the skin,” explains Dr. Steiger.

Doctors implant leadless pacemakers via a large vein in the leg. They advance a long thin tube, also known as a catheter, from the leg into the heart under x-ray guidance. The tip of the catheter contains the leadless pacemaker, which they place in the heart muscle. Once the pacemaker is confirmed to be in the right position, the doctor removes the catheter from the body, leaving the entire pacemaker system contained in the heart. 

Pacemaker follow-up

As part of the follow-up care post-surgery, patients see their doctors within a couple of weeks, then once a year afterwards. Pacemakers also send reports directly to the doctor every 3 months, detailing the health of the device. If the pacemaker finds any arrhythmias, it notifies the doctor sooner.

“If we see an arrhythmia that’s concerning, we may order more tests to see if there’s anything new going on. We may start a new or different medication. We may try a procedure to take care of the arrhythmia. Sometimes it requires reprogramming or recalibrating the device,” Dr. Steiger says.

How long does a pacemaker last?

Pacemaker batteries last between 6 and 13 years, sometimes longer. “It depends on person to person, and how much you use it,” explains Dr. Steiger. When it’s time for a new battery, doctors will install a completely new device.

“We make a small incision where the old device is, we take out the old device and replace it with a new one, and attach it to the existing wires,” Dr. Steiger says. Pacemakers may last even longer in the future, as the technology continues to improve.

Pacemaker risks

Pacemaker complications are fortunately rare. During implantation, some of the risks include infection, bleeding, or damage to the heart or lungs.

“There is a slight risk of infection over time. If it were to happen, it can be quite serious and require removal of the device,” says Dr. Steiger. Removing the pacemaker can be difficult, because over time the body creates scar tissue around the device and leads. “At the Brigham, we have a long history with our device extraction program. My colleagues specialize in removing these devices with specialized tools and an interdisciplinary team,” he says. “But the majority of people will never have to experience it.”

There is also a risk of pacemaker lead malfunction, which may require an additional procedure to replace the lead. Other rare risks include chronic pain from the pacemaker, feeling a chest sensation from the paced beats, or dislodgement of the leads from the heart muscle. 

A lot of patients forget they have a pacemaker. And that’s sort of the goal when we install it — we program it in a way that makes people feel better. And then they forget they have it.

Nathaniel Steiger, MD

Cardiac Electrophysiologist

Mass General Brigham

Things you can’t do with a pacemaker

Having a pacemaker probably won’t impact a patient’s day-to-day life. “Most household activities or items aren't going to cause any issues with the pacemaker. If you travel and you're going through airport security, you have a card to present to security. The x-ray machine itself is fine,” says Dr. Steiger.

MRI scanners, which use magnetic fields to create detailed images of the body, can also safely be used in patients with pacemakers. “The newer pacemakers are what we call MRI conditional, or MRI compatible. They have safe modes where in a monitored setting people can get an MRI safely. Even for patients who have older devices, some may be candidates to undergo an MRI scan. We use a very rigorous protocol to ensure we can do it safely,” Dr. Steiger explains.

People with pacemakers should take care with the following:

  • High arc welding: Avoid this type of construction technique, which generates electric fields and can interfere with the pacemaker’s function.
  • Cooking with an induction stove: Try to stay an arm’s length from an induction stove, which uses an electromagnetic field to heat the cookware directly. “As long as you’re not hugging your stove, you should be okay,” says Dr. Steiger.
  • Shooting rifles: If you use a rifle regularly, your doctor may install it in a different location to prevent the recoil of the gun hitting against the pacemaker.
  • Cancer treatment or radiation therapy: If you’re receiving radiation treatment for cancer located in the chest, “We want to make sure the pacemaker is out of the field of the radiation,” Dr. Steiger says.
  • Cell phones: Keep them at least 6 inches from the pacemaker. Avoid carrying a cell phone in a shirt pocket.

Because there aren’t a lot of activity restrictions attached to the device, most patients find they can get back to their regular lives after the procedure. “A lot of patients forget they have a pacemaker. And that’s sort of the goal when we install it—we program it in a way that makes people feel better. And then they forget they have it.” says Dr. Steiger. 

Learn about Mass General Brigham Heart services

Nathaniel Steiger


Cardiac Electrophysiologist