Electrophysiology | EKG | ECG

What is electrophysiology?

An electrophysiology procedure is a test to see if there is a problem with your heartbeat (heart rhythm) and to find out how to fix it. During this test, the doctor inserts one or more flexible tubes, called catheters, into a vein, typically in the groin or neck. Then he or she threads these catheters into the heart. At the tip of these catheters are electrodes, which are small pieces of metal that conduct electricity. The electrodes collect information about your heart's electrical activity.

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Diagnostic Test Types

Electrocardiogram (EKG/ECG)

If you are experiencing shortness of breath, chest discomfort, or a racing heart, your provider may recommend an EKG. Many patients have an EKG right in their provider’s office, while some may be referred to a medical facility that specializes in diagnostic technologies. An EKG tracks the electrical activity in your heart and shows:


  • Damage to the heart
  • How fast the heart is beating
  • Effects of drugs or assistive heart devices
  • Characteristics of the heart chambers
  • Abnormal electrical activity (arrhythmia) in the heart

What happens during an EKG?
Patients lie on a table and have patches or pads placed on their chest, arms, and legs. These pads are connected to a machine which reads the heartbeats and electric activity of the heart. The data is recorded digitally or written on a paper by the machine. The procedure usually takes only a few minutes. Medications can alter the results of an EKG so be sure to tell your provider if you are taking any drugs.

Cardiac Catheterization

Cardiac catheterization is a medical test to check and treat some heart conditions. The test lets your heart specialist see inside your arteries for blockages. Cardiac catheterization is used to diagnose and treat coronary artery disease, or CAD.

What happens during a cardiac catheterization?
Doctors use a thin flexible tube called a catheter to do the diagnostic exam. It is inserted through a vein in the arm or leg to reach the heart. Through the catheter, your doctor can view plaque buildup and often provide treatment at the same time. The patient is awake for the procedure, which does not hurt. A cardiac catheterization lets your doctor:


  • See if plaque has built up in your arteries and blocks blood flow. By putting dye in the catheter, your doctor can see your arteries using x-rays. The test is called a coronary angiography.
  • View blockages with the help of an ultrasound. Ultrasound uses sound waves to create images of the arteries that supply blood to your heart.
  • Take samples of blood and heart muscle, and do minor surgery to correct problems.

If coronary artery disease is detected during a cardiac catheterization procedure, your heart specialist may do the following treatments:


  • Angioplasty: A tiny balloon is put at the end of the catheter to unblock a blood vessel.
  • Stent placement: A stent is a small tube placed inside an artery to help blood flow. Sometimes stents are coated with medicine, which helps healing.

Angiogram/Angiography

An angiogram is an imaging procedure that allows your doctor to take pictures of your blood vessels and organs to check for blockages and narrowing. Angiograms are used to diagnose:


  • Aneurysms
  • Tumors
  • Blood clots
  • Cerebral vascular disease
  • Arterial Stenosis

If blockages and narrowing are found, your doctor may treat these issues during the angiogram procedure. There are different types of angiographies depending on the information the doctor needs.


  • A computed tomography (CT) angiogram, also known as a “cardiac CT scan,” is a series of x-rays of your arteries and veins. An injection of dye before the test helps doctors see the outlines of your vessels, arteries and veins.
  • A cardiac magnetic resonance angiography (MRA) test, also known as a “cardiac MRI” uses a big magnet and radio waves to see your blood vessels. Dye may be also be used during this procedure.

Exercise Stress Test

Some heart issues can be diagnosed more easily when the heart is beating faster than usual. Also known as an “exercise EKG,” this test tracks electrical activity of the heart during physical movement on a treadmill or stationary bike. Your doctor may recommend an exercise stress test before you start a cardiac rehabilitation program or, if you have:


  • Chest pain or pressure
  • Irregular heartbeat
  • Heart disease

What happens during an exercise stress test?
The test usually takes about 15 to 30 minutes and you should wear loose, comfortable clothing. A technician will attach pads to your chest, arms, and legs. First, the electrical activity of your heart will be measured while it is at rest. Then, you will be asked to walk or pedal and the electrical activity of your heart will be measured while it is beating faster. You may experience sweat, cramps, or soreness during the test and should report any symptoms to the technician.


Cardio Pulmonary Exercise Test (CPET)

The CPET is an exercise stress test that not only measures the electrical activity of your heart also assesses how well the heart, lungs, and muscles are working individually, and together. The full cardiopulmonary system is assessed during a CPET by measuring the amount of oxygen your body is using, the amount of carbon dioxide it is producing, your breathing pattern, and electrocardiogram (EKG) while you are riding a stationary bicycle. The CPET is also used to monitor changes in your disease condition, the effect of certain medications on your body, and if medical therapy is improving your condition.

Holter and Event Monitors (Ambulatory EKG/ECG, Continuous EKG/ECG, EKG Event Monitors)

Holter and event monitors are small, portable electrocardiogram devices that record your heart’s electrical activity for long periods of time while you do your normal activities.These monitors can record how fast your heart is beating, whether the rhythm of your heartbeats is steady or irregular, and the strength and timing of the electrical impulses passing through each part of your heart. Information from these recordings helps doctors diagnose an arrhythmia, or irregular heartbeat, and check whether treatments for the irregular heartbeat are working.

There are many types of monitors, such as episodic monitors, autodetect recorders, 30-day event recorders, and transtelephonic event monitors. Your doctor will decide which monitor is best for you. Most monitors have electrodes with sticky adhesive patches that attach to the skin on your chest. Some monitors and electrodes used for long-term recording may be implanted under your skin to make it easier for you to bathe and perform your daily activities. Your doctor will explain how to wear and use the monitor and tell you whether you need to adjust your activity during the testing period.

You should avoid magnets, metal detectors, microwave ovens, electric blankets, electric toothbrushes, and electric razors while using your monitor. Usually, you will be instructed to keep electronic devices such as cell phones, MP3 players, and tablets away from the monitor. After you are finished using the monitor, you will return it to your doctor’s office or the place where you picked it up. If you were using an implantable recorder, your doctor will remove it from your chest.

There is a small risk that the sticky patches that attach the electrodes to your chest can irritate your skin. You may have an allergic reaction to the electrode adhesive, but the reaction will go away once the electrodes are removed. If you are using an implantable recorder, you may get an infection or have pain where the device was placed under your skin. Your doctor can prescribe medicine to treat these problems.

Next Steps for Patients

While some patients are candidates for self-referral to our cardiovascular specialists, we recommend that you ask your primary care physician for help with the process. Find a Provider

Provider Referrals

If you are a provider who would like to refer a patient for MaineHealth cardiovascular imaging and diagnostic services, please review our clinical guidelines and call 207-885-9905. Clinical Guidelines
Source: National Heart, Lung, and Blood Institute; National Institutes of Health; U.S. Department of Health and Human Services.

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