How does a pacemaker work?

A pacemaker is a small device that is implanted in the chest (right or left side) and helps control the heartbeat. It is used to prevent the heart from beating too slowly and its implantation requires a surgical procedure.

Depending on the heart condition, one of the following types of pacemakers will be implanted:

  • Single-chamber pacemakers: This type of pacemaker usually carries electrical impulses to the right ventricle of the heart.
  • Dual-chamber pacemakers: This type of pacemaker carries electrical impulses to the right ventricle and right atrium of the heart to help control the timing of contractions between the two chambers.
  • Biventricular pacemakers: Biventricular pacemakers are for people who have heart failure and heartbeat problems. This type of pacemaker stimulates both lower chambers of the heart (right and left ventricles) so that the heart beats more efficiently.

Why is it implanted?

A pacemaker is implanted to help control the heartbeat. Your doctor may recommend a temporary pacemaker when you have a slow heartbeat (bradycardia) after a heart attack, surgery, or medication overdose, but otherwise your heartbeat is expected to recover. A pacemaker may be permanently implanted to correct chronic slow or irregular heartbeats or to help treat heart failure.

How does the heart beat?

The heart is a fist-sized muscular pump with four chambers, two on the left and two on the right. The upper chambers (right and left atria) and lower chambers (right and left ventricles) work with the heart\'s electrical system to keep it beating at an appropriate rate, usually 60 to 100 beats per minute for adults at rest.

The heart\'s electrical system controls the heartbeat, starting with a group of cells at the top of the heart (sinus node) and spreading to the bottom so that it contracts and pumps blood. Aging, damage to the heart muscle from a heart attack, some medications, and certain genetic conditions can cause an abnormal heart rhythm.

What does a pacemaker do?

Pacemakers work only when needed. If the heartbeat is too slow (bradycardia), the pacemaker sends electrical signals to the heart to correct the beat.

Some newer pacemakers also have sensors that detect body movement or breathing rate, prompting them to increase your heart rate during exercise as needed.

A pacemaker has two parts:

  • pulse generator. This small metal container houses a battery and the electrical circuit that controls the frequency of electrical impulses sent to the heart.
  • Wires (electrodes). One to three flexible insulated wires are placed in one or more chambers of the heart and send electrical impulses to match the heart rate. However, some newer pacemakers do not require leads. These devices, called wireless pacemakers, are implanted directly into the heart muscle.


Complications related to surgery to implant a pacemaker or having a pacemaker are rare, but may include the following:

  • Infection near the heart site where the device was implanted
  • Swelling, bruising, or bleeding at the pacemaker site, especially if you take blood thinners
  • Blood clots (thromboembolism) near the pacemaker site
  • Damage to blood vessels or nerves near the pacemaker
  • Lung collapse (pneumothorax)
  • Blood in the space between the lung and the chest wall (hemothorax)
  • Movement (displacement) of the device or leads

How do you prepare?

Before your doctor decides if you need a pacemaker, you\'ll have several tests to find the cause of your irregular heartbeat. Tests that are done before a pacemaker is placed may include:

  • Electrocardiogram. This quick and painless test measures the electrical activity of the heart. Adhesive patches (electrodes) are placed on the chest and sometimes on the arms and legs. They have wires that connect the electrodes to a computer that displays the results. A electrocardiogram it can show if the heart is beating too fast, too slow, or not at all.
  • Holter monitoring. A Holter monitor is a small, wearable device that tracks your heart rhythm. Your doctor may have you wear a Holter monitor for 1 to 2 days. During that time, the device records every heartbeat. Holter monitoring is especially helpful in diagnosing heartbeat-related problems that occur at unpredictable times. Some personal devices, such as smart watches, offer EKG monitoring. Ask your doctor if this is an option for you.
  • Echocardiogram. This noninvasive test uses sound waves to produce images of the heart\'s size, structure, and motion.
  • Stress test. Some heart problems appear only during exercise. For a stress test, an EKG is done before and right after you walk on a treadmill or ride a stationary bike. Sometimes a stress test is done along with echocardiography or nuclear medicine imaging.

Before the procedure

You\'ll probably be awake during the surgery to implant the pacemaker, which usually takes a few hours. The specialist will insert an IV into your forearm or hand and give you medicine called a sedative, which will help you relax. The chest is cleaned with a special soap.

Most pacemaker implants are done under local anesthesia to numb the area of the incisions. However, the amount of sedation needed for the procedure depends on the medical conditions you have. You may be fully awake or lightly sedated, or given general anesthesia (fully asleep).

during the procedure

One or more wires are inserted into a major vein under or near the collarbone and guided to the heart using x-ray imaging. One end of each wire is fixed in the correct position in the heart, while the other end is connected to the pulse generator, which is usually implanted under the skin near the collarbone.

Leadless pacemakers are smaller and generally require less invasive surgery to implant. The pulse generator and other parts of the pacemaker are contained within a single capsule. The doctor inserts a flexible sheath (catheter) into a vein in the groin and then guides the single component of the pacemaker through the catheter to the indicated position in the heart.

after the procedure

You will probably stay in the hospital for a day after having a pacemaker implanted. The pacemaker will be programmed to suit your heart rate needs. You will need to arrange for someone to drive you home from the hospital.

Your doctor may recommend that you avoid vigorous exercise or heavy lifting for about a month. Avoid putting pressure on the area where the pacemaker was implanted. If you feel pain in that area, ask your doctor if you can take over-the-counter medications, such as acetaminophen (Tylenol, others) or ibuprofen (Advil, Motrin IB, others).

special precautions

It is unlikely that your pacemaker will stop working properly due to electrical interference. Despite that, you should take some precautions:

  • Mobile phones. It\'s safe to talk on a cell phone, but you should keep it at least 6 inches (15 centimeters) away from your pacemaker. Don\'t keep your phone in your shirt pocket. When you talk on the phone, hold it to the ear opposite the side where your pacemaker was implanted.
  • Security systems. Going through a metal detector at the airport will not interfere with your pacemaker, although metal inside your pacemaker could set off the alarm. However, avoid standing near or leaning against a metal detection system.

    To avoid potential problems, carry an ID card that says you have a pacemaker.

  • Medical equipments. Make sure all your doctors and dentists know you have a pacemaker. Certain medical procedures, such as MRI, CT scans, radiation therapy for cancer, electrocautery to control bleeding during surgery, and shock wave lithotripsy to break up large kidney stones or gallstones may interfere with the pacemaker.
  • Power generating equipment. Stay at least 2 feet (61 cm) from welding equipment, high-voltage transformers, or motor-generator systems. If you work around such equipment, ask your doctor to arrange a test at your workplace to determine if the equipment affects your pacemaker.

Devices that are unlikely to interfere with your pacemaker include microwave ovens, televisions and remote controls, radios, toasters, electric blankets, electric shavers, and electric drills.


A pacemaker should improve symptoms caused by slow heartbeats, such as fatigue, lightheadedness, and fainting. Because most of today\'s pacemakers automatically adjust your heart rate according to your level of physical activity, they can allow you to return to a more active lifestyle.

Your doctor should check your pacemaker every 3 to 6 months. Tell your doctor if you gain weight, swell your legs or ankles, or feel faint or dizzy.

Your doctor can check most pacemakers remotely, which means you don\'t have to go to the office. The pacemaker sends information to the doctor, such as heart rate and rhythm, pacemaker function, and battery life.

Your pacemaker battery should last between 5 and 15 years. When the battery runs out, you\'ll have to have surgery to replace it. The procedure to change the pacemaker battery is usually quicker and requires less recovery time than the procedure to implant the pacemaker.

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