Iowa Health Book: Internal Medicine
Cardiovascular Division
Department of Internal Medicine
The University of Iowa Hospitals and Clinics
Written By
A. Aschoff, R.N.
K. Slotterback, R.N.
S. Small, R.N., M.A.
M. McCue, R.N.
In Collaboration With
The Medical Nursing Division and Physicians of the Cardiac Electrophysiology Service of the Department of Internal Medicine
Produced By
Hospital Information Services
Contents
Introduction
This information has been prepared to give you a better understanding of the diagnostic test called an electrophysiology study (EP study) and to describe what will happen before, during, and after the test. We believe that you will be more comfortable during this study if you know what to expect.
Your nurses and doctors will go over this information with you and answer any questions you have. Write down any questions as they come to mind.
Structure and function of the normal heart
The heart is a four-chambered muscular organ. The upper chambers are called atria and the lower chambers are called ventricles. The heart works as a pump supplying blood to all parts of the body.
Blood is pumped in an orderly sequence (see diagram). Blood from the body enters the right side of the heart and is pumped to the lungs. The oxygen-rich blood then returns to the left side of the heart and is pumped to the rest of the body.
How your heart beats
Your heart has its own electrical conduction system (see diagram). Each heartbeat is normally started in a special part of the heart called the sinus node. The electrical impulse from the sinus node travels down a pathway to the atrial-ventricular or AV node. Finally, the impulse travels down the pathways to the ventricles and causes them to squeeze, or contract. One impulse from the sinus node should result in one contraction, and therefore one heartbeat.
Arrhythmias and the EP study
What are arrhythmias?
When the electrical conduction system in the heart is changed, an abnormal heart rhythm can develop. Abnormal rhythms are called arrhythmias. Many things can change the electrical conducting system of the heart. The aging process or a previous heart attack is often the cause, but arrhythmias can also occur in young, healthy people.
Classification of arrhythmias
Arrhythmias are classified in a number of ways. One way is based on whether your heart beats too fast or too slow. If your heart beats more than 100 times per minute, you have tachycardia.
Tachycardias are classified by the location of the abnormal conduction. If the sinus node, the atria, or the AV node causes a fast rhythm, it is called supraventricular tachycardia, or SVT. Tachycardias may also begin in the ventricles. This fast rhythm is called ventricular tachycardia, or VT.
Bradycardias may be caused by a disruption or blockage anywhere in the normal conduction system. Bradycardias become a problem when the heart is pumping too slowly to maintain an adequate blood pressure, and blood supply is insufficient to vital organs (for example, the brain).
Some people have both brady- and tachyarrhythmias. There may be a normal heart rhythm at times, followed by periods of bradycardia or tachycardia.
Whether your heartbeat is too slow or too fast, the result may be a decreased pumping ability of the heart. When this happens, symptoms occur. Symptoms that can occur are dizziness, tiredness, blurred vision, shortness of breath, chest pain, and loss of consciousness. Since similar symptoms may result from other problems, careful evaluation is necessary to make a proper diagnosis.
The purpose of an EP study
Arrhythmias can be very dangerous and sometimes life-threatening. While most are treatable, the treatment will be based on the cause. For this reason, your doctors have decided that you need an electrophysiology study of your heart.
Before the study
The word electrophysiology is made up of two words. The first part of the word, electro, means electrical, and the second part of the word, physiology, means function. Therefore, an electrophysiology study is simply a study of the electrical function of your heart. This study will provide specific information about your arrhythmia. Once the doctor has this information, it is easier to select the appropriate treatment for you.
The evening before the test, the nursing staff will review this document with you and your family to clarify information and answer questions. A member of the SP team will also talk with you about the procedure.
Monitoring
Special monitors will be used to provide a continuous reading of your heart rhythm.
Intravenous (IV) lines
A small intravenous (IV) catheter will be placed in a vein in your hand or arm. This may be used to continuously administer fluids or it may be capped with a heparin lock for intermittent use.
Consent
An EP team doctor will explain why the procedure is necessary and what risks are involved for you. The degree of risk varies with each person and is related to your specific condition. After discussing the information, you will be asked to sign a consent form to indicate your permission for the study.
Skin preparation
The evening before the test, your skin will be scrubbed and hair shaved from potential catheter insertion sites. The most common site used is the groin. Occasionally the forearm is used. The purpose of the scrub is to provide a clean insertion site and reduce the chance of infection.
Eating and drinking
You will be asked not to eat or drink anything after midnight the night before your test. If your test is not scheduled until later in the day, you may have a liquid breakfast after which you must not eat or drink. You may take your morning pills with a sip of water.
Final preparation
You will not receive anything to put you to sleep before this test. It will be important for you to describe any sensations you may have during the test to the doctors in the EP laboratory. You should wear your dentures and a hospital gown without bottoms. You may wear your glasses if you wish. You should use the bathroom just before going into the lab because it may be several hours before you return to your room. An initial EP study usually takes three to five hours. Your family members can wait in your room or in the visitor's lounge and will be notified when you return to your room.
During the EP Study
The EP laboratory
The EP study is done in a special procedure room. This room is similar to an operating room and contains electronic equipment to be used during the EP study. You will lie on your back on a table and every effort will be made to see that you are comfortable. EKG patches will be placed on your chest to monitor your heart rhythm. Next, you will be covered by a sheet. A large x-ray camera will be positioned over your chest. The purpose of the x-ray camera is to help position the catheters.
Inserting the catheters
Catheters are long, thin, flexible wires that can be threaded through a blood vessel leading to your heart (see diagram). Usually, two catheters are used but, depending on the type of study to be performed, as many as four can be used.
Before inserting the catheters, the insertion site will be scrubbed with an antiseptic solution. When working with the catheters, the staff will wear gowns, masks, and gloves. All of these precautions are taken to protect you from infection.
Placement of the catheters should not cause any significant pain. Before inserting the catheters, the area will be numbed with a medication. You will feel a needle stick, but after that you should only feel pressure. While the catheters are in place you will probably not even be aware that they are there.
Recording and pacing
During the study, the catheters are moved to different locations in the heart and electrical activity is recorded. The catheters are also used to control how fast your heart beats and to add extra beats. This is called "pacing" your heart. You may be unaware of this pacing or you may feel your heart start to speed up, slow down, or skip a beat. If an arrhythmia starts, you may feel some of the same symptoms that caused you to seek medical attention. Please tell the EP staff what you feel. Let them know if you have shortness of breath, dizziness, light-headedness, or chest discomfort.
You may be given some medication during the procedure. Some drugs are given to mimic your body's response to stress and activity. Some drugs are given to prevent arrhythmias from occurring.
If the arrhythmia causes severe symptoms, it will be stopped immediately. If the arrhythmia does not stop on its own, it may be stopped by the same pacing impulse that started it. Occasionally, the arrhythmia must be stopped by an electrical shock applied to the chest. This is called a cardioversion.
After the test, the catheters will be removed. Firm pressure will be applied over the insertion site for about 15 minutes. This is necessary to prevent any bleeding from the insertion site. You will then be taken back to your room.
After the Study
Activity
Flat bed rest is necessary for two to eight hours after the study. During this time, it is important to keep the leg or arm used in the procedure straight to prevent bleeding from the insertion site. After the specified amount of bed rest, you will be able to resume your previous activity level.
Postprocedure care
Your nurse will be in the room frequently during the first hour after the study to take your blood pressure, heart rate, and check your insertion site for signs of bleeding. The pulses and temperatures of your feet will also be checked.
You will be instructed to apply pressure firmly to the insertion site if you cough or sneeze and while using the bedpan or urinal. If you should notice any bleeding at the site, notify your nurse immediately. If your back becomes uncomfortable, do not hesitate to ask the nurses for pain medications.
Eating and drinking
You will be able to resume your previous diet and your nurse will help you eat while you are flat in bed.
Results
Your doctors will discuss the test results and further plans with you and your family following the study.
If you are like most patients, a medication can be found that will effectively treat your arrhythmia. However, the first drug tried may not work. In this case, you will need to return to the EP laboratory in several days to test another drug. Repeat EP studies seldom last as long as the first study and usually take only one to two hours.
You may be offered an alternate form of treatment if for some reason your arrhythmia does not respond to medication. These alternatives are listed below. Your doctors and nurses will discuss them with you.
