What Is Electrophysiology?

An electrophysiology (EP) study tests for abnormal heartbeats or rhythms

An electrophysiology (EP) study uses the heart's electric signals to diagnose abnormal heartbeats or heart rhythms (arrhythmia).

During an EP study, three to five catheters (flexible wires) pass through IVs (also called sheaths) inserted into the groin or neck. With the aid of a video screen, a healthcare provider then guides the electrodes to the heart. An EP study is painless, though there is some pressure where the catheters enter the groin or neck.

Read below for more on what an EP study looks like, risks or potential complications, how to prepare for an EP study, what happens after an EP study, and how the results of an EP study are interpreted.

Microscope for electrophysiology

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Purpose of an Electrophysiology (EP) Study

An EP study is usually advisable when non-invasive testing methods, like an electrocardiogram (an EKG) or Holter monitor (a pocket-size battery-operated heart monitoring device), don't provide answers. EP studies can help determine:

  • How well the heart's electrical system is working
  • The reason behind an arrhythmia (irregular heartbeat)
  • How effective medications for irregular heartbeat are
  • Whether some of the heart's tissue can be removed to regulate the heartbeat (catheter ablation)
  • The need for a pacemaker or ICD (implantable cardioverter defibrillator), a device that tracks heart rhythm and releases an electric shock when arrhythmia occurs
  • Heart attack or cardiac arrest risk

Risks and Contradictions

EP studies are usually ordered when non-invasive procedures cannot find the root of an issue. There are some risks and contradictions associated with the test.

EP Study Risks

Though it is largely safe, EP studies can include some risk of side effects, including:

  • Arrhythmia that can require an electric shock to once again regulate the heart
  • Heart attack
  • Stroke
  • Damage to heart valves
  • Blood clots at the end of the catheter
  • Vein injury
  • Bruising, bleeding, or infection at IV insertion sites

Accuracy of Electrophysiology

EP studies can be more specific in identifying the exact cause of arrhythmia, at a rate of 75–95%. They are most accurate for determining the cause of arrhythmias.

Before the Test

To prepare for an EP study, you will likely be instructed to do the following.

  • Discuss any medications and supplements you are taking to check if you should discontinue any in preparation for the test.
  • Arrange for transportation to and from the test.
  • Sign a consent form.
  • Avoid food for six to eight hours.


An EP test takes about one to four hours, which includes time for anesthesia, shaving the area where the electrodes are inserted, conducting the test itself, and removing the IVs after the results are recorded.


An EP test is likely to take place in an EP laboratory (EP lab) or the catheterization lab (cath lab), where the patient lies on an X-ray table next to television screens and monitors. After the procedure, a patient can go to a recovery room for one to three hours.

Food and Drink

Patients undergoing an EP study are usually instructed to avoid food for six to eight hours before the test.

Cost and Health Insurance

The cost of an EP study can depend on the subject's insurance plan, but most plans usually cover the procedure as well as any other non-invasive tests that diagnose arrhythmia.

The cost of an EP study for a patient on Medicare can range from $60 to about $300, depending on the complexity of the study required (checking one atrium versus the whole heart, for example). Visiting an electrophysiologist for general concerns could cost about $100 to $200, depending on your insurance plan's location.

What to Bring

Before undergoing an EP study, you should bring a list of current medications and supplements to your healthcare provider. This is to determine if you should avoid any of them right before the test. On the day of an EP study, you should bring any hearing or vision aids you normally wear to the test.

Other Considerations

Considering the anesthesia and relaxation medications that precede an EP study, arranging transportation to and from your healthcare provider's office is an important consideration.

During the Test

The following is some of what you can expect before, during, and after an EP study.


You will likely need to sign a consent form before undergoing an EP study.

After giving your consent, a nurse (and/or anesthesiologist) will likely do the following:

  • Provide a sedative via IV to relax you
  • Clean and shave the area where the catheters will enter the groin, neck, and/or arm
  • Provide a numbing agent to the area where the electrodes will enter

Throughout the Test

Throughout your EP study, you'll likely feel:

  • Some pressure in the area where catheters are inserted (though the numbing agent will likely keep any pain at bay).
  • A bit of discomfort at the IV's insertion points: This could include stinging or tingling as the needle is inserted.
  • A faster heartbeat: Electric pulses will be sent to your heart to affect its heartbeat. If this makes you anxious or causes uncomfortable symptoms like nausea, chest pain, and dizziness, tell your healthcare provider immediately.

The EP study will then proceed with the following steps:

  • A thin needle will puncture through the skin, and a sheath (a small tube) will enter the vein or artery.
  • Three to five EP catheters with cameras are then inserted through the sheaths and directed to your heart by your healthcare provider via a video screen.
  • Electric pulses are then sent to the heart to make it beat differently, and the heart's electric signals are then recorded.


After your heart's signals are recorded, the IV lines are then removed. A nurse then stops any bleeding at IV insertion sites by applying pressure.

An EP study can take one to about four hours, after which you will likely go to a recovery room for four to six hours. It is advisable to remain still during recovery time. If you experience pain or bleeding, contact a nurse immediately.

After about six hours, you will likely be permitted to eat and then take any medications you have been prescribed or have been taking.

After the Test

Avoiding driving during the 24 hours after an EP study is advisable. However, normal activities can resume the next day. Refraining from picking up anything that weighs more than 10 pounds is also advisable. You can also remove any dressings for wounds the next day.

Speak to your healthcare provider about avoiding blood clots after your EP study via leg movements or walking, especially if your drive home is long. You might feel tired after an EP study, but that should resolve within a few days. You may notice that your heartbeat skips beats or beats at a higher rate.

Managing Side Effects

Side effects of an EP study can include:

  • New blood at insertion sites: If any new bleeding doesn't stop after applying pressure for about 20 minutes, go to an emergency room while continuing to apply pressure.
  • Bruising at insertion sites: This symptom should disappear in about four weeks.

The following side effects require medical attention:

  • Tingling wherever catheters were inserted
  • Cold or color change in hands or arms
  • Swelling, warmth, or more bruising at the puncture sites
  • Shortness of breath
  • Fever

Post-EP Study: Emergency Side Effects

If any of the following occurs after your EP study, call 911 immediately:

  • Uncontrolled bleeding at insertion sites
  • Symptoms of stroke or heart attack, like chest pain, lightheadedness, or heavy breathing
  • Swelling at puncture sites

Interpreting Results

When the results of an EP study are available can depend on your healthcare provider, and you will likely require a future appointment to discuss them.

Electrophysiology results can look like drawings of lifeline measurements. The results can provide insight into aspects of irregular heart rhythms, including:

  • Dysfunction in the electrical components of the heart, including the sinus node and the atrioventricular (AV) node, both of which contain electric signals in the heart
  • Tachycardia: a rapid heart rate
  • Results of ablation, an EP study that can indicate whether a treatment for arrhythmia is effective
  • Whether medication for irregular heartbeat is working
  • Whether a pacemaker or similar device is necessary or is effective if already installed
  • The likelihood of cardiac arrest in the future


Undergoing a repeat EP study (such as when following up on a pacemaker, for example) is possible; however, you should discuss the risks associated with the procedure with your healthcare provider.

Other tests for arrhythmia can help clarify diagnoses, including for longer-term conditions and other areas of the heart and body. For example:

  • Holter monitors or implantable loop recorders record heart rhythm over spans of time, which can help people whose arrhythmia happens without a set pattern
  • Blood tests can test hormone or mineral imbalances
  • Genetic testing can help determine whether specific genes are increasing the likelihood of arrhythmia in your family
  • Heart imaging tests can look at other areas of the heart for abnormalities like damaged tissue or structures

If your EP study indicates a problem, your healthcare provider might perform a catheter ablation to remove any damaged tissue from the heart during the EP study itself.

Other treatments might include:

  • Medication
  • A pacemaker or other device
  • Avoiding alcohol, smoking, and drug use
  • Health improvements, such as lowering blood pressure and/or losing weight if necessary
  • Daily exercise

Other Considerations

An EP study can help pinpoint the exact location of arrhythmia and provide a treatment plan. However, if you have doubts about your diagnosis, do keep an open dialogue with your healthcare provider about other available tests.

Requesting a copy of EP study results for a second opinion may also help.


An electrophysiology (EP) study uses catheters with cameras to determine the location and cause of arrhythmia. During an EP, IVs create punctures, and catheters are then inserted and guided with the help of video monitors. An EP study can come with some risks, including tissue damage. However, the test is largely safe.

EP studies come provided with anesthesia and calming medications, and patients usually stay awake throughout them. During an EP study, you might experience pressure where catheters are inserted. After your healthcare provider has inserted the catheters, they may apply an electric current to make the heart beat faster. They will then measure and record the electric signals in response.

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By Neha Kashyap
Neha is a New York-based health journalist who has written for WebMD, ADDitude, HuffPost Life, and dailyRx News. Neha enjoys writing about mental health, elder care, innovative health care technologies, paying for health care, and simple measures that we all can take to work toward better health.