The Vital Test That Helps Detect Abnormal Heart Rhythms

An electrophysiology study can help get to the bottom of a slow, fast or irregular heartbeat and get you back in rhythm.

Medically reviewed in September 2021

When your heart isn’t ticking the way it should, you need to find out why. A problem with the rate or rhythm of your heartbeat involves your heart’s electrical system.

Normally, the heart beats at a steady rhythm, or between 60 and 100 times per minute when you’re at rest. If you have an arrhythmia however, it could beat too quickly (tachycardia), too slowly (bradycardia), or in an irregular pattern.

Some abnormal heart rhythms need treatment because they can be dangerous, or in certain cases, deadly. An electrophysiology study (EPS) can determine if you have a heart rhythm disorder and what kind it is. This special test helps doctors decide the best way to reset your out-of-sync heart.

The basics of arrhythmias
Your heart’s electrical system controls the rate and rhythm of its four chambers: two upper atria and two lower ventricles. Electrical impulses normally start in the right atrium and flow through pathways in the heart. This creates coordinated, steady beats. Bad signaling anywhere along this route can cause an issue with your heart rhythm. Some problems trigger obvious symptoms, including a fluttering sensation or pounding in your chest, dizziness or shortness of breath, but other heart rhythm problems may go unnoticed.   

Before an EPS, doctors use tests including electrocardiograms, heart monitors and certain other exams to look for a suspected arrhythmia, says Juan Rodriguez, MD, a cardiac electrophysiologist at LewisGale Medical Center in Salem, Virginia. But sometimes those tests can’t pick up irregular heartbeats, as arrhythmias can be unpredictable; your heart may beat normally most of the time but then fall out of rhythm periodically. Sometimes, an arrhythmia is detected but doctors can’t tell exactly where the problem starts in your heart.

Who gets an EPS?
An EPS can rule out or confirm an arrhythmia and pinpoint the spot where your electrical system is going haywire. Your doctor may order one if you:

  • Have a known arrhythmia: Your doctor may want to get a closer look at how electricity flows through your heart to make better treatment decisions.
  • Are at increased risk of sudden cardiac death: Certain heart problems make it more likely you could go into cardiac arrest—an emergency situation where your heart stops. An EPS can help doctors understand your personal risk and how to prevent it from happening.
  • Lose consciousness: Sudden fainting spells (known as syncope) can be a big red flag for an arrhythmia.
  • Are getting a cardiac catheter ablation: An EPS is done before this procedure, which uses heat or cold to destroy small areas of the heart to block bad electrical signals.

Your doctor may strongly suspect that you have a rhythm problem and order an EPS if you have stubborn symptoms that aren’t explained by other health problems. These include:

  • Heart palpitations, which can feel like a flutter, a skipped beat or a racing heartbeat
  • Dizziness or light-headedness
  • Weakness or fatigue
  • Pounding in the chest
  • Shortness of breath

How is an EPS done?
Electrophysiology studies are invasive, meaning they occur inside your body. The test is done in a high-tech hospital laboratory in a very controlled setting under the close supervision of electrophysiologists and a team of specialists.

You may be awake during the procedure but be given medication to make you relax and feel comfortable. If your doctor plans to perform an ablation as well, you may be given general anesthesia, Dr. Rodriguez notes.

During the test, several catheters (narrow, flexible tubes) are inserted into a vein usually in your groin. The catheters have electrodes on the tip and are carefully guided into various areas of your heart. The medical team sees continuous live images on a video screen.

The electrodes record your heart’s electrical activity. The electrophysiologist uses small electrical impulses to slow down or speed up heartbeats, hoping to trigger a suspected arrhythmia. This “pacing” technique can unmask what kind of arrythmia you have and the exact tissue responsible, Rodriguez explains. An arrhythmia triggered during the procedure will either resolve on its own, or the electrophysiologist will use drugs, more pacing or other techniques to get your heart back into rhythm.

An EPS usually takes several hours. You’ll have to lie still in recovery for a few more hours as your small puncture wound starts to heal

What happens next?
You’ll need to be sure you understand and follow the doctor’s discharge directions. It's also important to know what to look for and what to do if you spot anything that the doctor says could be a sign of trouble, like swelling or increased bruising at the site of your incision.

Once you return home, you should limit your activity for 24 hours and avoid strenuous lifting for at least one week. Avoiding prolonged sitting and be sure to stretch or get up and walk periodically to help prevent blood clots from forming.

Complications from the procedure, which may include damage to a heart valve, bleeding, blood clots and infection, are rare and usually linked to placement of the catheters. Be sure to seek immediate medical attention if your incision site becomes painful or warm to the touch, or if you develop chest pain, shortness of breath, lightheadedness or have a fluttering or pounding sensation in your chest.

The doctors will tell you what your test results reveal. If you’re diagnosed with a heart rhythm disorder, your treatment will depend on what type you have, your symptoms, or if you’re at risk for major complications.

Ventricular arrhythmias—arrhythmias that begin in the heart’s ventricles—may be concerning. The mildest type is a premature ventricular contraction (PVC), often described as a "skipped beat." These are usually harmless unless they're very frequent or you have heart disease. Ventricular tachycardia and fibrillation however cause the lower chambers to beat way too fast. As a result, they can’t fill with enough blood to be pumped to the brain and other vital organs. You may suddenly lose consciousness or go into cardiac arrest.

Treatments for ventricular arrhythmias may include all or some of the following:

  • Medications that control the rate and rhythm of your heart
  • Cardiac catheter ablation
  • A device called an implantable cardioverter defibrillator, which can detect a fast or erratic heartbeat and shock the heart back into rhythm
  • Healthy lifestyle adjustments, such as being more active, maintaining a healthy weight, easing stress and not smoking

Supraventricular arrhythmias—arrhythmias that begin in the atria, or the heart’s upper chambers—can cause troubling symptoms like fatigue and shortness of breath. “They can ruin your quality of life and cause long term damage like heart failure, but in general, they aren’t lethal in the short term,” Rodriguez says.

The most common arrhythmia, atrial fibrillation (AFib), is a fast and irregular heartbeat that occurs when the atria fibrillate (quiver) so blood can’t move as effectively into the ventricles. As a result, blood clots can form and move from the heart to the brain. This is why people with AFib are five times more likely to have a stroke than people without it, Rodriguez says.  

Treatment is often one or more of the following:

  • Blood thinners to prevent clots
  • Medications that control the rate and rhythm of your heart
  • Electrical cardioversion (low voltage electric shock) to restore a normal heartbeat
  • ​Cardiac catheter ablation
  • Surgery to disrupt abnormal electrical signals or to implant a pacemaker to restore the heart’s natural rate and rhythm.

Your doctor may ask you about all the medicines you take because some can trigger arrhythmias. Your lifestyle matters too. Heart disease, high blood pressure, electrolyte imbalances, drinking too much caffeine or alcohol, or using certain illegal drugs can also trigger an irregular heart rhythm.

Bottom line: If you have a suspected arrhythmia, your doctor may refer you to a specialist, called a cardiac electrophysiologist, who can map your heart’s electrical system and determine if you have an irregular heartbeat and how it should be managed.  

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