Electrophysiology study

Electrophysiology study
Electrophysiology study
Synonyms	Electrophysiological study, EP study
Purpose	Diagnose abnormal heart rhythms
Test of	Electrical activity within the heart

Last updated February 05, 2025

A cardiac electrophysiology study (EP test or EP study) is a minimally invasive procedure using catheters introduced through a vein or artery to record electrical activity from within the heart.^[1] This electrical activity is recorded when the heart is in a normal rhythm (sinus rhythm) to assess the conduction system of the heart and to look for additional electrical connections (accessory pathways), and during any abnormal heart rhythms that can be induced.^[2] EP studies are used to investigate the cause, location of origin, and best treatment for various abnormal heart rhythms, and are often followed by a catheter ablation during the same procedure.^[3]

Preparation

It is important for patients not to eat or drink for up to 12 hours before the procedure. This is to prevent vomiting, which can result in aspiration, and also cause severe bleeding from the insertion site of the catheter. Failure to follow this simple preparation may result in dangerous consequences. In general, small amounts of water can be consumed up to 2 hours before the exam. Patients should try to schedule the exam at a time when they will be having symptoms and will not need to drive for 2 to 3 days.

If the reason for the EP study is for an arrhythmia, then antiarrhythmic drugs may be held to increase the likelihood of being able to induce the rhythm. Additionally, beta blockers or calcium channel blockers may be held as well. Anticoagulants may be held or continued depending on the scenario.

Procedure

An EP study is typically performed in an EP lab (a specialized cath lab). These are specially equipped operating rooms that usually contain:^[3]

an x-ray machine capable of acquiring live X-ray video images (a fluoroscope)
equipment to record electrical signals from the heart
a stimulator to electrically excite the heart and control the heart rate
ablation equipment to destroy abnormal tissue
an electroanatomic mapping system that tracks and records the catheter position in 3D and associated electrical signals
ready access to cardiac medications such as adenosine, atropine, dopamine, and isoproterenol
ready access to an assortment of introducer sheaths and catheters
surgical instruments for device implants including scalpels, electrocautery, retractors, forceps, hemostats, and scissors

The procedure may be performed awake under local anaesthetic, or under general anaesthetic. Monitoring equipment is attached including an automated blood pressure cuff and a pulse oximeter to measure the oxygen saturation of the blood. A peripheral venous cannula is generally inserted to allow medication to be given such as sedatives, anesthesia, or drugs.^[3]

An access site that will allow catheters to be passed to the heart via an artery or vein is shaved and cleaned, usually in the groin. The blood vessels used to reach the heart (the femoral or subclavian veins, and sometimes the femoral artery) are punctured before a guidewire and plastic sheath are inserted into the vessel using the Seldinger technique.^[3]

EP Study and inducibility

Once the catheter is in and all preparations are complete elsewhere in the lab, the EP study begins. The X-ray machine will give the doctor a live view of the heart and the position of the electrodes. He will guide the (steerable) electrodes to the correct position inside the heart. The electrophysiologist begins by moving the electrodes along the conduction pathways and along the inner walls of the heart, measuring the electrical activity along the way.

The next step is pacing the heart, this means he/she will speed up or slow down the heart by placing the electrode at certain points along the conductive pathways of the heart and control the depolarization rate of the heart. The doctor will pace each chamber of the heart one by one, looking for any abnormalities. Then the electrophysiologist tries to provoke arrhythmias and reproduce any conditions that have resulted in the patient's placement in the study. This is done by injecting electric current into the conductive pathways and into the endocardium at various places. Last, the electrophysiologist may administer various drugs (proarrhythmic agents) to induce arrhythmia (inducibility of VT/VF^[4]). If the arrhythmia is reproduced by the drugs (inducible), the electrophysiologist will search out the source of the abnormal electrical activity. The entire procedure can take several hours.

Ablation

If at any step during the EP study the electrophysiologist finds the source of the abnormal electrical activity, they may try to ablate the cells that are misfiring. This is done using high-energy radio frequencies (similar to microwaves) to effectively heat up the abnormal cells, to form scar tissue. This can be painful with pain felt in the heart itself, the neck and shoulder areas. A more recent method of ablation is cryoablation, which is considered less risky and less painful.^[5]

Recovery

When the necessary procedures are complete, the catheter is removed. Firm pressure is applied to the site to prevent bleeding. This may be done by hand or with a mechanical device. Other closure techniques include an internal suture and plug. If the femoral artery was used, the patient will probably be asked to lie flat for several hours (3 to 6) to prevent bleeding or the development of a hematoma. Trying to sit up or even lift the head is strongly discouraged until an adequate clot has formed. The patient will be moved to a recovery area where he/she will be monitored.

For patients who had a catheterization at the femoral artery or vein (and even some of those with a radial insertion site), in general recovery is fairly quick, as the only damage is at the insertion site. The patient will probably feel fine within 8 to 12 hours after the procedure, but may feel a small pinch at the insertion site. After a short period of general rest, the patient may resume some minor activity such as gentle, short, slow walks after the first 24 hours. If stairs must be climbed, they should be taken one step at a time and very slowly. All vigorous activity must be postponed until approved by a physician.

It is also important to note that unless directed by a doctor, some patients should avoid taking blood thinners and foods that contain salicylates, such as cranberry-containing products until the clot has healed (1–2 weeks).

Complications

As with any surgical procedure, cardiac catheterizations come with a generic list of possible complications. One of the complications that are sometimes reported involves some temporary nerve involvement. Sometimes a small amount of swelling occurs that can put pressure on nerves in the area of the incision. Venous thrombosis is the most common complication with an incidence ranging between 0.5 and 2.5%.^[6] There have been reports of patients feeling like they have hot fluid like blood or urine running down their leg for up to a month or two after the incision has healed. This usually passes with time, but patients should tell their doctor if they have these symptoms and if they last.

More severe but relatively rare complications include: damage or trauma to a blood vessel, which could require repair; infection from the skin puncture or from the catheter itself; cardiac perforation, causing blood to leak into the sac around the heart and compromising the heart's pumping action, requiring removal using a needle under the breast bone (pericardiocentesis); hematoma at the site(s) of the puncture(s); induction of a dangerous cardiac rhythm requiring an external shock(s); a clot may be dislodged, which may travel to a distant organ and impede blood flow or cause a stroke; myocardial infarction; unanticipated reactions to the medications used during the procedure; damage to the conduction system, requiring a permanent pacemaker; death.

Related Research Articles

Cardiology is the study of the heart. Cardiology is a branch of medicine that deals with disorders of the heart and the cardiovascular system. The field includes medical diagnosis and treatment of congenital heart defects, coronary artery disease, heart failure, valvular heart disease, and electrophysiology. Physicians who specialize in this field of medicine are called cardiologists, a sub-specialty of internal medicine. Pediatric cardiologists are pediatricians who specialize in cardiology. Physicians who specialize in cardiac surgery are called cardiothoracic surgeons or cardiac surgeons, a specialty of general surgery.

The diagnostic tests in cardiology are methods of identifying heart conditions associated with healthy vs. unhealthy, pathologic heart function.

<span class="mw-page-title-main">Electrocardiography</span> Examination of the hearts electrical activity

Electrocardiography is the process of producing an electrocardiogram, a recording of the heart's electrical activity through repeated cardiac cycles. It is an electrogram of the heart which is a graph of voltage versus time of the electrical activity of the heart using electrodes placed on the skin. These electrodes detect the small electrical changes that are a consequence of cardiac muscle depolarization followed by repolarization during each cardiac cycle (heartbeat). Changes in the normal ECG pattern occur in numerous cardiac abnormalities, including:

A pacemaker, also known as an artificial cardiac pacemaker, is an implanted medical device that generates electrical pulses delivered by electrodes to one or more of the chambers of the heart. Each pulse causes the targeted chamber(s) to contract and pump blood, thus regulating the function of the electrical conduction system of the heart.

Wolff–Parkinson–White syndrome (WPWS) is a disorder due to a specific type of problem with the electrical system of the heart involving an accessory pathway able to conduct electrical current between the atria and the ventricles, thus bypassing the atrioventricular node. About 60% of people with the electrical problem developed symptoms, which may include an abnormally fast heartbeat, palpitations, shortness of breath, lightheadedness, or syncope. Rarely, cardiac arrest may occur. The most common type of irregular heartbeat that occurs is known as paroxysmal supraventricular tachycardia.

Atrial flutter (AFL) is a common abnormal heart rhythm that starts in the atrial chambers of the heart. When it first occurs, it is usually associated with a fast heart rate and is classified as a type of supraventricular tachycardia (SVT). Atrial flutter is characterized by a sudden-onset (usually) regular abnormal heart rhythm on an electrocardiogram (ECG) in which the heart rate is fast. Symptoms may include a feeling of the heart beating too fast, too hard, or skipping beats, chest discomfort, difficulty breathing, a feeling as if one's stomach has dropped, a feeling of being light-headed, or loss of consciousness.

AV-nodal reentrant tachycardia (AVNRT) is a type of abnormal fast heart rhythm. It is a type of supraventricular tachycardia (SVT), meaning that it originates from a location within the heart above the bundle of His. AV nodal reentrant tachycardia is the most common regular supraventricular tachycardia. It is more common in women than men. The main symptom is palpitations. Treatment may be with specific physical maneuvers, medications, or, rarely, synchronized cardioversion. Frequent attacks may require radiofrequency ablation, in which the abnormally conducting tissue in the heart is destroyed.

<span class="mw-page-title-main">Cardiac electrophysiology</span> Science of elucidating, diagnosing, and treating the electrical activities of the heart

Cardiac electrophysiology is a branch of cardiology and basic science focusing on the electrical activities of the heart. The term is usually used in clinical context, to describe studies of such phenomena by invasive (intracardiac) catheter recording of spontaneous activity as well as of cardiac responses to programmed electrical stimulation - clinical cardiac electrophysiology. However, cardiac electrophysiology also encompasses basic research and translational research components. Specialists studying cardiac electrophysiology, either clinically or solely through research, are known as cardiac electrophysiologists.

<span class="mw-page-title-main">Cardiac catheterization</span> Insertion of a catheter into a chamber or vessel of the heart

Cardiac catheterization is the insertion of a catheter into a chamber or vessel of the heart. This is done both for diagnostic and interventional purposes.

<span class="mw-page-title-main">Catheter ablation</span> Removal or termination of an electrical pathway from parts of the heart

Catheter ablation is a procedure that uses radio-frequency energy or other sources to terminate or modify a faulty electrical pathway from sections of the heart of those who are prone to developing cardiac arrhythmias such as atrial fibrillation, atrial flutter and Wolff-Parkinson-White syndrome. If not controlled, such arrhythmias increase the risk of ventricular fibrillation and sudden cardiac arrest. The ablation procedure can be classified by energy source: radiofrequency ablation and cryoablation.

Lown–Ganong–Levine syndrome (LGL) is a pre-excitation syndrome of the heart. Those with LGL syndrome have episodes of abnormal heart racing with a short PR interval and normal QRS complexes seen on their electrocardiogram when in a normal sinus rhythm. LGL syndrome was originally thought to be due to an abnormal electrical connection between the atria and the ventricles, but is now thought to be due to accelerated conduction through the atrioventricular node in the majority of cases. The syndrome is named after Bernard Lown, William Francis Ganong, Jr., and Samuel A. Levine.

Clinical cardiac electrophysiology, is a branch of the medical specialty of cardiology concerned with the study and treatment of rhythm disorders of the heart. Cardiologists with expertise in this area are usually referred to as electrophysiologists. Electrophysiologists are trained in the mechanism, function, and performance of the electrical activities of the heart. Electrophysiologists work closely with other cardiologists and cardiac surgeons to assist or guide therapy for heart rhythm disturbances (arrhythmias). They are trained to perform interventional and surgical procedures to treat cardiac arrhythmia.

Pre-excitation syndrome is a heart condition in which part of the cardiac ventricles are activated too early. Pre-excitation is caused by an abnormal electrical connection or accessory pathway between or within the cardiac chambers. Pre-excitation may not cause any symptoms but may lead to palpitations caused by abnormal heart rhythms. It is usually diagnosed using an electrocardiogram, but may only be found during an electrophysiological study. The condition may not require any treatment at all, but symptoms can be controlled using medication or catheter ablation.

The following outline is provided as an overview of and topical guide to cardiology, the branch of medicine dealing with disorders of the human heart. The field includes medical diagnosis and treatment of congenital heart defects, coronary artery disease, heart failure, valvular heart disease and electrophysiology. Physicians who specialize in cardiology are called cardiologists.

Michel Haïssaguerre is a French cardiologist and electrophysiologist. His investigations have been the basis for development of new markers and therapies for atrial and ventricular fibrillation.

Junctional ectopic tachycardia (JET) is a rare syndrome of the heart that manifests in patients recovering from heart surgery. It is characterized by cardiac arrhythmia, or irregular beating of the heart, caused by abnormal conduction from or through the atrioventricular node. In newborns and infants up to 6 weeks old, the disease may also be referred to as His bundle tachycardia or congenital JET.

Atrial fibrillation is an abnormal heart rhythm (arrhythmia) characterized by rapid and irregular beating of the atrial chambers of the heart. It often begins as short periods of abnormal beating, which become longer or continuous over time. It may also start as other forms of arrhythmia such as atrial flutter that then transform into AF.

<span class="mw-page-title-main">Hein Wellens</span> Dutch cardiologist (1935–2020)

Henrick Joan Joost Wellens, M.D., (1935–2020) was a Dutch cardiologist who is considered one of the founding fathers of clinical cardiac electrophysiology - a discipline which enables patients with cardiac arrhythmias to have catheter electrode mapping and ablation.

Arrhythmias, also known as cardiac arrhythmias, are irregularities in the heartbeat, including when it is too fast or too slow. Essentially, this is anything but normal sinus rhythm. A resting heart rate that is too fast – above 100 beats per minute in adults – is called tachycardia, and a resting heart rate that is too slow – below 60 beats per minute – is called bradycardia. Some types of arrhythmias have no symptoms. Symptoms, when present, may include palpitations or feeling a pause between heartbeats. In more serious cases, there may be lightheadedness, passing out, shortness of breath, chest pain, or decreased level of consciousness. While most cases of arrhythmia are not serious, some predispose a person to complications such as stroke or heart failure. Others may result in sudden death.

Yaariv Khaykin is a Canadian cardiologist and a clinical researcher in the area of electrophysiology. He is the director of the Newmarket Electrophysiology Research Group at the Southlake Regional Health Centre. He has published research into complex ablation and pioneered cardiac ablation methods.

References

↑ Josephson, Mark E. (2015-08-10). Josephson's clinical cardiac electrophysiology : techniques and interpretations. Preceded by: Josephson, Mark E. (Fifth ed.). Baltimore, MD. ISBN 9781496326614. OCLC 938434294.{{cite book}}: CS1 maint: location missing publisher (link)
↑ Karen.E.Thomas and Peter J. Zimetbaum (2011). "Electrophysiology study: Indications and interpretations". In Gan-Xin Yan; Peter R. Kowey (eds.). Management of Cardiac Arrhythmias. Contemporary cardiology. Vol. 34. Hanumana Press. pp. 123–140. doi:10.1007/978-1-60761-161-5. ISBN 978-1-60761-160-8. PMC 2218957 . PMID 21253086.
1 2 3 4 Handbook of cardiac electrophysiology : a practical guide to invasive EP studies and catheter ablation. Murgatroyd, Francis D. London: ReMEDICA Pub. 2002. ISBN 9781901346374. OCLC 48363139.{{cite book}}: CS1 maint: others (link)
↑ Saksena, Sanjeev; Camm, A. John (12 December 2011). Electrophysiological Disorders of the Heart: Expert Consult – Online and Print. Elsevier Health Sciences. ISBN 978-1437709711 – via Google Books.
↑ "Cryoablation for the Treatment of Atrial Fibrillation" . Retrieved May 23, 2015.
↑ Peter W. Macfarlane; Adriaan van Oosterom; P. Kligfield; Michiel Janse; J. Camm, eds. (2010). Comprehensive Electrocardiology (2nd ed.). Springer. p. 1146. ISBN 978-1-84882-047-0.

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[1] Josephson, Mark E. (2015-08-10). Josephson's clinical cardiac electrophysiology : techniques and interpretations. Preceded by: Josephson, Mark E. (Fifth ed.). Baltimore, MD. ISBN 9781496326614. OCLC 938434294.{{cite book}}: CS1 maint: location missing publisher (link)

[2] Karen.E.Thomas and Peter J. Zimetbaum (2011). "Electrophysiology study: Indications and interpretations". In Gan-Xin Yan; Peter R. Kowey (eds.). Management of Cardiac Arrhythmias. Contemporary cardiology. Vol. 34. Hanumana Press. pp. 123–140. doi:10.1007/978-1-60761-161-5. ISBN 978-1-60761-160-8. PMC 2218957 . PMID 21253086.

[Murgatroyd-3] 1 2 3 4 Handbook of cardiac electrophysiology : a practical guide to invasive EP studies and catheter ablation. Murgatroyd, Francis D. London: ReMEDICA Pub. 2002. ISBN 9781901346374. OCLC 48363139.{{cite book}}: CS1 maint: others (link)

[4] Saksena, Sanjeev; Camm, A. John (12 December 2011). Electrophysiological Disorders of the Heart: Expert Consult – Online and Print. Elsevier Health Sciences. ISBN 978-1437709711 – via Google Books.

[5] "Cryoablation for the Treatment of Atrial Fibrillation" . Retrieved May 23, 2015.

[6] Peter W. Macfarlane; Adriaan van Oosterom; P. Kligfield; Michiel Janse; J. Camm, eds. (2010). Comprehensive Electrocardiology (2nd ed.). Springer. p. 1146. ISBN 978-1-84882-047-0.

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