An electrophysiological study (EP study) is an invasive procedure that
tests the heart's electrical system. The electrical system of the heart
generates the heart beat.
During an EP study, a small, plastic catheter (tube) is inserted through
a vein in the groin (or neck, in some cases) and is threaded into the
heart, using a special type of X-ray, called fluoroscopy, to guide the
catheter. Once in the heart, electrical signals are sent through the
catheter to the heart tissue to evaluate the electrical conduction
system contained within the heart muscle tissue.
There are several ways in which EP studies may be performed to assist in
diagnosing electrical conduction system abnormalities of the heart. For
example, a dysrhythmia/arrhythmia (an abnormal rhythm) may be
deliberately stimulated by a doctor during the EP study so that the
underlying abnormal electrical circuitry can be identified. Likewise, in
order to evaluate the effectiveness of an antiarrhythmic medication, an
attempt may be made to stimulate the dysrhythmia.
Mapping, another type of EP study, may be done to locate the point of
origin of a dysrhythmia. If a location is found that is the cause of the
dysrhythmia, an ablation (removal of the spot by freezing or heated
radiofrequency waves) may be done, which should stop the dysrhythmia.
The results of the study may help the doctor determine further
therapeutic measures, such as inserting a pacemaker or implantable
defibrillator, adding or changing medications, performing additional
ablation procedures, or providing other treatments.
Other related procedures that may be used to assess the heart include
resting or exercise electrocardiogram (ECG), Holter monitor,
signal-averaged ECG, cardiac catheterization, chest X-ray, computed
tomography (CT scan) of the chest, echocardiography, magnetic resonance
imaging (MRI) of the heart, myocardial perfusion scans, radionuclide
angiography, and cardiac CT scans. Please see these procedures for
heart is, in the simplest terms, a pump made up of muscle tissue. Like
all pumps, the heart requires a source of energy in order to function.
The heart's pumping action is regulated by an electrical conduction
system that coordinates the contraction of the various chambers of the
In the heart, an electrical stimulus is generated by the sinus node
(sinoatrial node, or SA node), which is a small mass of specialized
tissue located in the right atrium (right upper chamber) of the heart.
The sinus node generates an electrical stimulus regularly at 60 to 100
times per minute (for adults) under normal conditions. This electrical
stimulus travels down through the conduction pathways (similar to the
way electricity flows through power lines from the power plant to your
house) and causes the heart's lower chambers to contract and pump out
blood. The right and left atria (the two upper chambers of the heart)
are stimulated first and contract a short period of time before the
right and left ventricles (the two lower chambers of the heart). The
electrical impulse travels from the sinus node to the atrioventricular
node (also called AV node), where impulses are slowed down for a very
short period, then continue down the conduction pathway via the bundle
of His into the ventricles. The bundle of His divides into right and
left pathways to provide electrical stimulation to the right and left
When a problem develops with the heart’s rhythm, there may or may not be
any symptoms. The presence of a dysrhythmia is usually determined by an
electrocardiogram (ECG). An ECG is one of the simplest and fastest
procedures used to evaluate the electrical activity of the heart. By
placing electrodes at specific locations on the body (chest, arms, and
legs), a tracing of the electrical activity can be obtained.
The electrical activity of the heart is measured by the ECG machine,
electronically interpreted, and printed out for the doctor’s information
and further interpretation.
One of the most common heart dysrhythmias/arrhythmias is premature
ventricular beats, or PVCs. PVCs are just what they sound like: the
ventricles beat sooner than they should. This means that the ventricle
is contracting and pumping out blood before the atrium above it has
completely pumped its blood volume into the ventricle. Most of the time,
PVCs are harmless. In fact, almost everyone has them at one time or
another. However, if PVCs occur too frequently (more than several times
per minute), the heart is unable to pump an adequate volume of blood to
the body, which can cause symptoms such as weakness, fatigue,
palpitations, or low blood pressure.
Other types of rhythm problems can have similar effects. Problems may
occur when the heart beats too fast, too slow, or with an irregular
rhythm. But whether the heart is beating too fast, too slow, or too
irregularly, the effects are often the same as one or more of those
described above. Some additional examples of rhythm problems include:
Atrial fibrillation. Occurs when the atria beat
irregularly and too fast
Ventricular fibrillation. Occurs when the
ventricles beat irregularly and too fast
Bradycardia. Occurs when the heart beats too
Tachycardia. Occurs when the heart beats too
Heart block. Occurs when the electrical signal
is delayed or blocked after leaving the SA node. There are
several types of heart blocks, and each one has a distinctive
Some dysrhythmias, however, occur only intermittently, and cannot be
seen on a routine ECG or even on a more sophisticated type of ECG, such
as a signal-averaged ECG or a Holter monitor procedure (a prolonged
recording of the heart rhythm over 24 hours or longer). If the doctor
suspects a problem with the heart's conduction system and cannot
adequately diagnose the problem with other tests or procedures, then he
or she may also decide that an electrophysiology study is appropriate.
An EP study may be performed for the following reasons:
To evaluate a symptomatic patient (a patient having dizziness,
fainting, weakness, palpitation, or other symptoms) for a rhythm
problem when other noninvasive tests have been inconclusive
To locate the source of a rhythm problem
To assess the effectiveness of medication(s) given to treat a
To evaluate the effectiveness of a pacemaker
There may be other reasons for your doctor to recommend an
Possible risks of an EP study include, but are not limited to, the
Stimulation of more severe rhythm problems
Bleeding from the catheter insertion site(s)
Damage to the vessel at the catheter insertion site(s)
Infection of the catheter site(s)
Perforation of the heart (rare)
You may want to ask your doctor about the amount of radiation from the
fluoroscopy used during the procedure and the risks related to your
particular situation. It is a good idea to keep a record of your past
history of radiation exposure, such as previous scans and other types of
X-rays, so that you can inform your doctor. Risks associated with
radiation exposure may be related to the cumulative number of X-ray
examinations and/or treatments over a long period of time.
If you are pregnant or suspect that you may be pregnant, you should
notify your health care provider due to risk of injury to the fetus from
an EP study. Radiation exposure during pregnancy may lead to birth
defects. If you are lactating, or breastfeeding, you should notify your
health care provider.
Patients who are allergic to or sensitive to medications or latex should
notify their doctor.
For some patients, having to lie still on the procedure table for the
length of the procedure may cause some discomfort or pain.
There may be other risks depending on your specific medical condition.
Be sure to discuss any concerns with your doctor prior to the procedure.
Your doctor will explain the procedure to you and offer you the
opportunity to ask any questions that you might have about the
You will be asked to sign a consent form that gives your
permission to do the test. Read the form carefully and ask
questions if something is not clear.
Notify your doctor if you are sensitive to or are allergic to
any medications, iodine, latex, tape, or anesthetic agents
(local and general).
You will need to fast for a certain period of time prior to the
procedure. Your doctor will notify you how long to fast, usually
If you are pregnant or suspect that you may be pregnant, you
should notify your doctor.
Notify your doctor if you have any body piercing on your chest
Notify your doctor of all medications (prescription and
over-the-counter) and herbal supplements that you are taking.
Notify your doctor if you have heart valve disease, as you may
need to receive and antibiotic prior to the procedure.
Notify your doctor if you have a history of bleeding disorders
or if you are taking any anticoagulant (blood-thinning)
medications, aspirin, or other medications that affect blood
clotting. It may be necessary for you to stop some of these
medications prior to the procedure.
Your doctor may request a blood test prior to the procedure to
determine how long it takes your blood to clot. Other blood
tests may be done as well.
Notify your doctor if you have a pacemaker.
If a sedative is given before the procedure, you may need
someone to drive your home afterwards.
The area around the catheter insertion (groin area) may be
Based on your medical condition, your doctor may request other
An EP study may be performed on an outpatient basis or as part of your
stay in a hospital. Procedures may vary depending on your condition and
your doctor’s practices.
Generally, an EP study follows this process:
You will be asked to remove any jewelry or other objects that
may interfere with the procedure.
You will be asked to remove clothing and will be given a gown to
You will be asked to empty your bladder prior to the procedure.
An intravenous (IV) line will be started in your hand or arm
prior to the procedure for injection of medication and to
administer IV fluids, if needed.
You will be placed in a supine (on your back) position on the
You will be connected to an ECG monitor that records the
electrical activity of the heart and monitors the heart during
the procedure using small, adhesive electrodes. Your vital signs
(heart rate, blood pressure, breathing rate, and oxygenation
level) will be monitored during the procedure.
There may be several monitor screens, showing your vital signs
and the images of the catheter being moved through the body into
You will receive a sedative medication in your IV before the
procedure to help you relax. However, you will likely remain
awake during the procedure.
Your pulses below the IV site may be checked and marked with a
marker so that the circulation to the limb below the site can be
checked after the procedure.
A local anesthetic will be injected into the skin at the
insertion site. You may feel some stinging at the site for a few
seconds after the local anesthetic is injected.
Once the local anesthetic has taken effect, a sheath, or
introducer, will be inserted into the blood vessel. This is a
plastic tube through which the catheter will be inserted into
the blood vessel and advanced into the heart.
One or more catheters will be inserted through the sheath into
the blood vessel. The physician will advance the catheter
through the blood vessel into the right side of the heart.
Fluoroscopy (a special type of X-ray that is displayed on a TV
monitor), may be used to assist in advancing the catheter to the
Once the doctor has the catheter(s) placed properly, the
electrical testing will begin by sending very small electrical
impulses to certain areas within the heart. If a dysrhythmia
occurs, you may begin to feel lightheaded or dizzy. Medication
will be given in your IV to treat the dysrhythmia.
Alternatively, a shock will be delivered to stop the
dysrhythmia. You will be sedated before this type of shock is
If a certain area of tissue is found to be causing a
dysrhythmia, the doctor may perform an ablation to eliminate the
tissue. This is done with radio waves (radiofrequency ablation)
or cryothermy (cryoablation). The energy is delivered through
the catheter to the tissue.
If you notice any discomfort or pain, such as chest pain, neck
or jaw pain, back pain, arm pain, shortness of breath, or
breathing difficulty, let the doctor know.
Once the procedure has been completed, the catheter(s) will be
removed from the insertion site. The doctor or an assistant will
hold pressure on the insertion site so that the blood can begin
to form a clot at the site and stop the bleeding.
Once the bleeding has stopped, a bandage will be placed on the
You will be assisted to slide from the table onto a stretcher so
that you can be taken to the recovery area. NOTE: If the
insertion was in the groin, you will not be allowed to bend your
leg for a few hours. To help you remember to keep your leg
straight, the knee of the affected leg may be covered with a
sheet and the ends will be tucked under the mattress on both
sides of the bed to form a type of loose restraint.
In the hospital
After the procedure, you may be taken to the recovery room for
observation or returned to your hospital room. You will remain flat in
bed for a few hours after the procedure. The circulation and sensation
of the limb where the catheter was inserted will be monitored. A nurse
will monitor your vital signs, the insertion site, and
circulation/sensation in the affected leg or arm.
You should immediately inform your nurse if you feel any chest pain or
tightness, or any other pain, as well as any feelings of warmth,
bleeding, or pain at the insertion site in your leg or arm.
Bed rest may vary from two to six hours depending on your specific
In some cases, the sheath or introducer may be left in the insertion
site. If so, the period of bed rest will be prolonged until the sheath
is removed. After the sheath is removed, you may be given a light meal.
You may be given pain medication for pain or discomfort related to the
insertion site or having to lie flat and still for a prolonged period.
You may resume your usual diet after the procedure, unless your doctor
After the specified period of bed rest has been completed, you may get
out of bed. The nurse will assist you the first time you get up, and
will check your blood pressure while you are lying in bed, sitting, and
standing. You should move slowly when getting up from the bed to avoid
any dizziness from the long period of bed rest.
When you have completed the recovery period, you may be discharged to
your home unless your doctor decides otherwise. If this procedure was
performed on an outpatient basis, you must have another person drive you
Once at home, you should monitor the insertion site for bleeding,
unusual pain, swelling, and abnormal discoloration or temperature change
at or near the injection site. A small bruise is normal. If you notice a
constant or large amount of blood at the site that cannot be contained
with a small dressing, notify your doctor.
It will be important to keep the insertion site clean and dry. Your
doctor will give you specific bathing instructions.
You may be advised not to participate in any strenuous activities. Your
doctor will instruct you about when you can return to work and resume
Notify your doctor to report any of the following:
Fever and/or chills
Increased pain, redness, swelling, or bleeding or other drainage
from the insertion site
Coolness, numbness and/or tingling, or other changes in the
Your doctor may give you additional or alternate instructions after the
procedure, depending on your particular situation.
The content provided here is for informational purposes only, and was
not designed to diagnose or treat a health problem or disease, or
replace the professional medical advice you receive from your physician.
Please consult your physician with any questions or concerns you may
have regarding your condition.
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procedure and related health conditions. We hope you find these sites
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