An arrhythmia is any disorder of your heart rate or rhythm. It means that your heart beats too quickly, too slowly, or with an irregular pattern. Most arrhythmias result from problems in the electrical system of the heart. If your arrhythmia is serious, you may need a cardiac pacemaker or an implantable cardioverter defibrillator (ICD). They are devices that are implanted in your chest or abdomen.

A pacemaker helps control abnormal heart rhythms. It uses electrical pulses to prompt the heart to beat at a normal rate. It can speed up a slow heart rhythm, control a fast heart rhythm, and coordinate the chambers of the heart.

An ICD monitors heart rhythms. If it senses dangerous rhythms, it delivers shocks. This treatment is called defibrillation. An ICD can help control life-threatening arrhythmias, especially those that can cause sudden cardiac arrest (SCA). Most new ICDs can act as both a pacemaker and a defibrillator. Many ICDs also record the heart's electrical patterns when there is an abnormal heartbeat. This can help the doctor plan future treatment.

Getting a pacemaker or ICD requires minor surgery. You usually need to stay in the hospital for a day or two, so your doctor can make sure that the device is working well. You will probably be back to your normal activities within a few days.

Heart disease, also called cardiovascular disease, can have serious consequences. It’s the leading cause of death for men and women in the United States. Medical devices approved by the U.S. Food and Drug Administration (FDA), such as pacemakers and defibrillators, have extended and improved the lives of millions of people living with heart disease.

The FDA evaluates certain devices for safety and effectiveness before they can be marketed to the public. These medical devices include certain devices used to treat cardiovascular disease, cardiovascular conditions, and other related issues. Many of these FDA-approved medical devices can be implanted in a person’s body, while others are used outside the body. Health care providers determine which cardiovascular devices, if any, are best for each patient.

Below are some categories of FDA-approved devices used to treat various cardiovascular issues. Types of heart devices include:

Automated external defibrillators (AEDs): Portable and automatic, these devices are often found in public places and can save lives. They can help restore normal heart rhythm in patients whose hearts suddenly and unexpectedly stop pumping blood, an event called cardiac arrest. AEDs analyze heart rhythm and can help rescuers determine whether a shock is needed to restore a normal heartbeat. These devices are not difficult to use, but training in the use of AEDs is highly recommended. Learn more about AEDs on the FDA’s website.

Cardiac ablation catheters: Long, thin flexible tubes that are threaded into or onto the heart, cardiac ablation catheters treat abnormally rapid heartbeats. They work by modifying small areas of heart tissue that are causing abnormal heart rhythms.

Cardiovascular angioplasty devices: These are long, thin, flexible tubes that are threaded into a heart or other blood vessel to open narrowed or blocked areas. They are intended to improve blood flow to the heart, reduce chest pain, and treat heart attacks.

Cardiac pacemakers: Small and battery-powered, pacemakers are implanted into the body. Used when the heart beats too slowly, they monitor the organ’s electrical impulses and, when needed, deliver electrical stimulation to make it beat at a more appropriate rate.

Implantable cardioverter defibrillators (ICDs): These devices monitor heart rhythms and deliver shocks if dangerously fast rhythms are detected. Many record the heart’s electrical patterns when certain abnormal rhythms occur, allowing doctors to review the patterns.

Prosthetic (artificial) heart valves: Used for replacing diseased or dysfunctional heart valves, which direct blood flow through the heart, these are available in two forms. Mechanical valves are made of man-made materials. The second type, called “bioprosthetic” valves, are made from tissue taken from animals or human cadavers.

Stents: Small, lattice-shaped, metal tubes that are inserted permanently into an artery, stents are intended to help improve blood flow. Some contain drugs that may reduce the chance that arteries will become blocked again.

Ventricular assist devices (VADs): Mechanical pumps that are intended to help weak hearts pump blood effectively, VADs were originally approved for short-term use until donor hearts became available. Some are now approved for long-term therapy in patients with severe heart failure who are not candidates for heart transplants.

When to Seek Medical Help

If you have questions or concerns about your heart, talk to your primary care doctor. If you feel like you’re having a heart attack or other emergency medical issues, immediately call 911.

Know the warning signs and symptoms of a heart attack. The chances of survival are greater when emergency treatment begins quickly.

Sudden cardiac arrest occurs when the heart suddenly and unexpectedly stops pumping blood. If cardiac arrest does occur, rapid treatment with an AED can be life-saving. Defibrillation is a time-sensitive issue. The probability of survival decreases by 7 percent to 10 percent for every minute that a victim stays in a life-threatening arrhythmia.

Emergency first-responders are typically equipped with and trained to use AEDs. AEDs are also often found in public areas, and people with CPR and AED training can use them to help a person in cardiac arrest.

Sudden cardiac arrest occurs when the heart suddenly and unexpectedly stops pumping blood. It can happen to anyone, at any time, and signs include sudden collapse and immediate loss of consciousness.

Unlike heart attacks, which are caused by a blockage in an artery to the heart, sudden cardiac arrest is caused when the heart’s electrical system malfunctions. This produces abnormal heart rhythms, called arrhythmias, that make the heart unable to pump blood.

If cardiac arrest does occur, rapid treatment with a medical device called an automated external defibrillator (AED) can be life-saving.

An AED is a type of computerized defibrillator that automatically analyzes the heart rhythm in people who are experiencing cardiac arrest. When appropriate, it delivers an electrical shock to the heart to restore its normal rhythm. The conversion of a ventricular arrhythmia to its normal rhythm by an electrical shock is called defibrillation.

Defibrillation is time-sensitive. The probability of survival decreases by 7 percent to 10 percent for every minute that a victim stays in a life-threatening arrhythmia.

The U.S. Food and Drug Administration (FDA) regulates AEDs as medical devices and evaluates them for safety and effectiveness before they are marketed.

Many AEDs Are in Plain Sight

You can find AEDs in many public places, including offices, schools, shopping malls, grocery stores, and airports.

Emergency first-responders are typically equipped with and trained to use AEDs. Some people with underlying cardiac conditions can be at a higher risk of sudden cardiac arrest. Your health care provider can tell you if a home AED is something you should consider.

How AEDs Work

An AED system includes an AED device and accessories, such as a battery, pad electrodes, and if applicable, an adapter. The devices give verbal instructions to users.

This is how they work:

• The user turns on the AED and follows the voice prompts. Some devices turn on automatically when the user opens the lid.
• The user attaches two sticky pads with sensors (called electrodes) on the chest of the person in cardiac arrest.
• The electrodes send information about the person’s heart rhythm to a processor in the AED, which then analyzes the rhythm to find out whether an electric shock is needed.
• If a defibrillation shock is needed, the AED uses the voice prompts to instruct when to press a button to deliver the shock. In some devices, the voice prompts announce that a shock is going to be delivered and the AED delivers the shock without intervention by the user.

Training to Use AEDs

AEDs are not difficult to use, but training in the use of AEDs is highly recommended. This training, in connection with CPR training, is offered by many major health organizations. Some training is available online.

Classes can teach you how to recognize the signs of a sudden cardiac arrest, when to call emergency medical services, how to do CPR, and how to use an AED.

Some people may be afraid to use an AED because they’re worried something may go wrong. But most states’ Good Samaritan laws and the Federal Cardiac Arrest Survival Act provide some protection for bystanders who respond to emergencies.

But as always, in an emergency, call 911 immediately. If you’re somewhere that has an emergency response system that includes a clearly visible number, call that number for assistance. In either case, an operator can give instructions on how you can help someone who has sudden cardiac arrest.

How the FDA Regulates AEDs

As part of its regulatory oversight, the FDA closely monitors reports of device malfunctions, and reviews reports from consumers and manufacturers of AEDs.

Although the FDA regulates AEDs as medical devices, it does not regulate the resuscitation guidelines for the use of these devices.

In February 2015, the FDA required manufacturers to have “premarket approval” before marketing AED devices and accessories necessary for the functionality of the AED, to better ensure quality design and manufacturing practices. Premarket approval is the most stringent type of device marketing review required by the FDA, and approval is based on a determination by the FDA, relying on valid scientific evidence, that there is a reasonable assurance that the device is safe and effective for its conditions of use.

The FDA maintains a list of AED devices that are FDA-approved. Certain AEDs that do not appear on the FDA-approved list are considered “legacy devices.” Although some of these legacy devices are still in use, they may no longer be legally marketed.

What this means for you:

If you own an AED, check the FDA’s list of approved AED devices to confirm the device is FDA-approved. Contact the AED manufacturer with any questions or concerns.

If a cardiac arrest emergency happens and an AED is available, know that AEDs can save lives, even legacy devices. The potential life-saving benefits of FDA-approved AEDs when used as intended outweigh the probable risks of using them, when accompanied by adequate directions and appropriate warnings. You should be confident in using these devices in life-threatening situations.

Pacemakers, implantable cardioverter defibrillators (ICDs) and other implantable electronic heart devices and radiation procedures

X-ray imaging and CT scans can damage implantable electronic heart devices such as pacemakers, implantable cardioverter defibrillators (ICDs), and others. The chances of damage are extremely low. The recommendations on this page will help prevent damage to these devices from radiation procedures.

The FDA continues to receive a very limited number of reports of problems associated with people with implantable pacemakers and ICDs undergoing CT imaging. Potential problems may include:

• loss of consciousness
• an irregular, rapid heart rate (atrial fibrillation)
• a slower than normal heart rate (bradycardia)
• a rapid, fluttering or pounding heart (palpitations)
• device failure
• device power-on reset (“device reboot”)
• memory/data corruption
• device reset to default pacing
• early battery depletion
• in extremely rare cases, death

Even though the reports we received occurred during CT scanning, there is little evidence that CT exposure was the cause of these events.

Based on the available evidence, the chances of implantable electronic heart device problems due to CT are very low. The risk of problems can be reduced by following the recommendations below.

Recommendations for people with implantable electronic heart devices

If your doctor recommends CT scans for medical reasons, be aware the chances of a problem occurring is extremely low. You can help reduce the risk by doing the following:

• Tell the doctor who ordered the CT scan, as well as the tech performing the scan, that you have an implanted pacemaker or other device. This will help them plan imaging that minimizes the risk of problems.
• Tell the radiology tech and your physician immediately if you experience symptoms such as lightheadedness or palpitations during or immediately after the CT scan.
• Tell the doctor who is monitoring your device at your next regularly scheduled appointment that you have had a CT scan, so they can check the device to make sure it is working correctly.

Recommendations for physicians ordering a CT scan

If a patient has a pacemaker or ICD, it should NOT stop you from performing an appropriate, medically indicated CT scan. The probability of an adverse event being caused by exposing these devices to CT irradiation is extremely low and it is greatly outweighed by the clinical benefit of a medically indicated CT examination. CT continues to be the preferred tomographic imaging technology for patients with these devices. Magnetic Resonance Imaging (MRI) may also be an option for MR Conditional pacemakers or ICDs if the conditions of safe MR use can be met. An MR Unsafe device should not enter the MR environment and any device without explicit MR labeling should be considered MR Unsafe.

• Communicate with the radiologist and CT tech to help them plan imaging that will minimize the risks of adverse effects.
• Communicate with the physician who is monitoring the implanted pacemaker or defibrillator to ensure that they check the device at the next regularly scheduled appointment after the CT exam.

Recommendations for radiologists and radiologic technologists

If a patient has a pacemaker or ICD, it should NOT stop you from performing an appropriate, medically indicated CT scan. The probability of an adverse event being caused by exposing these devices to CT irradiation is extremely low and it is greatly outweighed by the clinical benefit of a medically indicated CT examination. CT continues to be the preferred tomographic imaging technology for patients with these devices. Magnetic Resonance Imaging (MRI) may also be an option for MR Conditional pacemakers or ICDs if the conditions of safe MR use can be met. An MR Unsafe device should not enter the MR environment and any device without explicit MR labeling should be considered MR Unsafe.

CT imaging facilities can use the following recommendations to develop protocols for planned and for urgently needed CT scans.

• Use CT radiographs (for example: scouts or localizer views) while setting up the CT scan to verify if any implanted pacemaker or ICD is present and if so, identify its location relative to the programmed scan range. Note: CT radiography, scout or localizing scans have not been associated with X-ray interference with electronic medical devices.
  • If possible, avoid including the implanted device inside the scanning range. It is important to ensure that CT images of the prescribed anatomy are taken so that the necessary diagnostic information is obtained. Confirm the required anatomic range with the supervising radiologist.
  • For CT procedures in which the medical device is located within the programmed scan range, you should minimize direct X-ray exposure to the electronics of the implanted medical device by using:
    • the lowest dose consistent with the needed level of diagnostic image quality and
    • a lower dose delivery rate, which can be accomplished by using a longer rotation time or lower pitch value, if appropriate for the ordered CT exam.
  • Imaging exams that would involve scanning directly over the electronics of the implanted device for more than several seconds, require additional care because of the potential for pacing to be inhibited for 30 or more seconds or a defibrillating shock to be applied. Examples of these scans are CT perfusion exams or interventional procedures such as CT fluoroscopy. If the procedure is urgently needed, careful monitoring of the device during and after the procedure is required.
• Be mindful that interference is possible and be ready to stop the scan if the patient experiences adverse symptoms. Although adverse symptoms are rare, they could include lightheadedness from slow heartbeat (bradycardia) or palpitations.

Recommendations for doctors who are monitoring the implantable device

The probability of risks to pacemakers and ICDs from CT exposure is extremely low. However, as a precaution, you should check the device after it was exposed to CT X-ray radiation, at the next scheduled patient checkup. Although rare, the following problems with implantable electronic heart devices have been reported:

• Power on reset (“device reboot”)
• Battery depletion
• Detected noise
• Changes in device programming (reset to default, shock counter resetting)
• Inappropriate ICD shocks
• Capacitor charging
• Corrupted memory
• Communications/interrogation issues
• Over-sensing

Some consumer electronic devices, such as certain cell phones and smart watches, include high field strength magnets. Recent studies have shown that consumer electronic devices with high field strength magnets may cause certain implanted medical devices to switch to “magnet mode” and suspend normal operations until the magnet is moved away from the medical device.

Many implanted medical devices are designed with a “magnet mode” to allow for safe operation during certain medical procedures such as undergoing an MRI scan. These safety features are typically engaged by physicians with the use of a high field strength magnet that is placed near the implanted device placing it into a “magnet mode.” Removal of the magnetic field causes the device to return to normal operation.

Precautions for Patients with Pacemakers and Other Implanted Medical Devices

The FDA recommends patients keep any consumer electronic devices that may create magnetic interference, including cell phones and smart watches, at least six inches away from implanted medical devices, in particular cardiac defibrillators. Many implanted medical devices have FDA-approved information written for patients (patient labeling), which cautions patients to keep all cell phones and smart watches at least six inches from the implanted medical device.

People with implanted medical devices may want to take some simple precautions, including:

• Keep the consumer electronics, such as certain cell phones and smart watches, six inches away from implanted medical devices.
• Do not carry consumer electronics in a pocket over the medical device.
• Check your device using your home monitoring system, if you have one.
• Talk to your health care provider if you are experiencing any symptoms or have questions regarding magnets in consumer electronics and implanted medical devices.

When near high strength magnets, devices with a magnetic safe mode could stop working or change how the device works. For example, a cardiac defibrillator may be unable to detect tachycardia events. Or it may change the operational mode of the devices such as turning on asynchronous (i.e., two or more events not happening at the same time) mode in a pacemaker.

Cardiac implanted electronic devices are intended to support heart rhythm disorders, such as slow or fast heart rates. When the device stops working, a patient may experience dizziness, loss of consciousness or even death if therapy is not delivered when lifesaving shocks are required.

It is important to emphasize the following: to avoid interference between cell phones and smart watches and your heart device, keep them at least six inches (15 centimeters) away from implanted medical devices. Also, do not place cell phones, smart watches, and other consumer electronics close to your implanted medical device.

The FDA is aware of published articles which describe the effect that sufficiently strong magnetic fields can turn on the magnetic safe mode when in close contact. The FDA also conducted its own testing on some products that use the high field strength magnet feature and have confirmed the magnetic field is both consistent with the publications and strong enough to turn on the magnetic safety mode of the medical devices in question. The FDA believes the risk to patients is low, and the agency is not aware of any adverse events associated with this issue at this time.

The FDA continues to monitor all relevant scientific information about this ongoing issue and will continue to take appropriate action, including informing the public and providing additional information, if the need arises based on its risk analysis.