• A pacemaker is a small device implanted in your chest that can send electrical signals into your heart if it isn't beating properly. 
• Pacemakers are made out of titanium, a lithium battery, and wires that are called leads. 
• You may need a pacemaker if you have bradycardia, or a slow heartbeat, especially when it is caused by sick sinus syndrome or heart block. 
• This article was medically reviewed by John Osborne, MD, PhD, and the Director of Cardiology for Dallas-based State of the Heart Cardiology.
• Visit Insider's homepage for more stories.

Your heart has an internal pacemaker called the sinus node. It's a group of cells, located on top of your heart, that sends electrical signals into the heart and controls your heartbeat. 

Sometimes, the sinus node can become damaged, or it can malfunction. And when the electrical signals can't reach the heart — often resulting in a heart rhythm disorder — you may need a pacemaker. 

A pacemaker is a small device made out of titanium, a lithium battery, and wires. Just like the internal pacemaker we're born with, a pacemaker can send electrical signals into the heart. These signals cause the heart to squeeze, which generates a pulse, and keeps the heart beating properly. 

You may need a pacemaker if you have a heart rhythm disorder

When your heart doesn't beat regularly, it is called an arrhythmia, or a heart rhythm disorder. An irregular heartbeat can be too fast or too slow, and it may lead to symptoms of fatigue, dizziness, and lightheadedness. 

"If we can correlate these symptoms with a slower heartbeat, then that's when your own internal pacemaker is not working so well," says Shephal Doshi, MD, director of cardiac electrophysiology and pacing at Providence Saint John's Health Center. 

A slow heartbeat is typically defined as fewer than 60 beats per minute and is called bradycardia. This may indicate sick sinus syndrome or heart block, and these are the underlying conditions that often warrant a pacemaker. 

Sick sinus syndrome is the most common reason behind a pacemaker placement. It occurs when the node of cells that act as a pacemaker becomes damaged, diseased, or lose functionality with aging. 

As a result, the electrical signals in your heart are no longer firing fast enough, according to Doshi, and this causes bradycardia. A pacemaker is placed to take over, making sure the heart is beating as often as it should. Sick sinus syndrome is more common among older adults, and one in 600 adults over the age of 65 will experience it, according to Harvard Health Publishing.

Heart block occurs when the electrical signal that directs the heartbeat is partially or completely blocked, and parts of the heart can't get the signal from the sinus node. This can also cause a slower heartbeat and a pacemaker may be needed to help conduct that signal, according to Doshi.

To determine if you will need a pacemaker, your doctor may use an electrocardiogram to measure your heartbeat or ask you to wear a Holter monitor, which is worn over an extended period of time while you go about your day-to-day life.

What to expect from pacemaker surgery 

During surgery, the battery of the pacemaker is implanted under the skin of the chest wall. It is a short surgery, taking less than half an hour, according to Adam Splaver, MD, a clinical cardiologist. 

Wires, called leads, are attached to the battery and snaked through your veins to the muscle of the heart. You will remain awake during your surgery, but a local anesthetic is used for numbing the location of your incision. 

Pacemakers have an internal monitoring system and you can follow the battery life to know when it's time for a replacement. Since the device itself is mostly a battery, you'll essentially need to replace the pacemaker altogether, with the wires left in place. 

"The battery life on these devices can typically last 10 years," says Doshi. "We can change the battery in an outpatient procedure." This means that, although your pacemaker will need to be replaced eventually, it usually won't require an overnight hospital stay. 

For individuals with a slow heartbeat, having a pacemaker can improve quality of life, make it possible for you to return to normal exercise, and keep you living longer.

"Quality of life after pacemaker surgery is normal, except for not having the ability to raise your arms above your head for six weeks or more," says Splaver. While most patients return to daily life in the few days after surgery, you'll likely be asked to take it easy and refrain from vigorous physical activity. 

In addition, technology that has a strong magnetic component could interfere with your pacemaker. For this reason, it is important to talk with your doctor about your pacemaker if you're having an MRI, and keep distance from industrial equipment like electrical generators or industrial welders.

Related stories about heart health:

• What is bradycardia? How to know if your heart rate is too low
• What is tachycardia, and when a high heart rate is dangerous
• A heart murmur is often innocent, but it can be dangerous
• What is AFib? Danger signs and treatments for atrial fibrillation
• What is a good resting heart rate, for adults and kids
• How to lower your heart rate from anxiety, or a panic attack
• What is heart rate variability? How to measure HRV and what it means

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