Cardiology in Critical Care

Electrophysiology Studies: A Guide for Patients

nursebob 07/25/10


This booklet 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 booklet with you and answer any questions you have. You may write down questions as they come to mind in the space provided in the back of this booklet.

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 pathways 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 conduction system of the heart. A previous heart attack or other scarring of the heart is often the cause, but arrhythmias can also occur in young, healthy people with apparently normal structure of the heart.

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 less than 60 times per minute, you have "bradycardia". If your heart beats more than 100 times per minute, you have "tachycardia".

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). Not all bradycardias are abnormal, or a sign of illness. Some very beneficial medicines produce slow heart rates and protect the heart from stress.

Tachycardias are classified by the location of abnormal conduction. If the abnormal rhythm originates from the upper chambers of the heart, it is called "supraventricular tachycardia", or SVT. Tachycardias may also originate in the lower chambers, or ventricles. This fast rhythm is called "ventricular tachycardia", or VT.

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 heart beat 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.

Before the test, your doctors and nurses will review this information with you and your family to clarify information and answer questions. A member of the Electrophysiology team will also talk with you about the procedure. If your EP study is to be performed as an outpatient, that is, without prior admission to the hospital, this information will be provided to you in a clinic setting or on the telephone.

If you are admitted to the hospital prior to your EP study, special monitors will be used to provide a continuous reading of your heart rhythm

Intravenous (IV) Lines
A small intravenous (IV) catheter may be placed in a vein in your hand or arm. This may be used to continuously administer fluids, or it may be covered with a cap for intermittent use. The purpose of this IV is to provide the nurses and doctors with a quick means of administering medications, should your heart rhythm abnormality occur.

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 this information, you will be asked to sign a consent form to indicate your permission for the study.

Skin Preparation
Prior to the EP study, your skin will be washed with a special soap and the hair shaved from potential catheter insertion sites. The most common site used is the groin, or the area at the crease of the leg about midway between the center of your body and your hip. Occasionally the forearm, neck or collarbone areas are used. The purpose of this washing 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 clear liquid breakfast, after which you must not eat or drink. You may take your morning pills with a sip of water. All your medicines will be reviewed, and some may be withdrawn prior to the test.

Final Preparation
You will not receive anything to put you to sleep before this test. It is important for you to describe sensations you have during the test to the staff in the EP laboratory. Medicines that sedate people may interfere with the ability to find the abnormal heart rhythm, but each patient is treated individually and you may discuss this issue with the EP team physicians and nurses.

If you have dentures and they are tight-fitting, you may wear them during the study. You may also wear your glasses and watch if you wish. You should wear a hospital gown without bottoms, but may wear your socks if you wish. You should use the bathroom just before going to the lab because it may be several hours before you return to your room. A bedpan or urinal will be made available to you, should you need it during the study. It is sometimes necessary to insert a catheter into the bladder for continuous drainage during longer procedures. If this is planned, it will be inserted early in the procedure. An initial EP study takes an average of two and a half hours; however, they may range from one to six hours. Your family members can wait in your room or in one of several lounges, and will be notified when your study is finished.

During the Study
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 you 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 camera is to help position the catheters in the heart.

Inserting the Intravenous Catheters
Catheters are flexible hollow plastic tubes, much like the intravenous catheter in your arm or hand, only larger to be placed in larger central veins. These are placed most commonly in veins, but occasionally in arteries, depending upon the type of study you are undergoing. Usually, two catheters are used, but, depending on the type of study to be performed, as many as five can be used. The purposes of these catheters are both to provide access to the vein or artery, for placement of pacing wires into the heart, and for administration of medications or fluids.

Before inserting the catheters, the insertion sites 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 and some burning or stinging, but after that you should feel only pressure while the catheters are being placed. After these catheters are in place, you will probably not even be aware that they are there.

Positioning the Heart Catheters
Long, thin, flexible wires, referred to as pacing wires, or intra-cardiac catheters, are advanced through the IV catheter and up into the heart chambers under the guidance of an x-ray camera (see diagram). These pacing wires are used to both record the electrical patterns from inside the heart and to "pace" the heart. Pacing the heart is delivery of very small amounts of electricity to the heart muscle through the tip of the catheter. This causes a heart beat, and allows the electrophysiologist to compare your heart's response to paced beats to already known normal responses. Approximately half of the patients undergoing this procedure are aware of each heart beat, and therefore, feel their heart speed up, slow down, or "skip a beat". Many other people are completely unaware of the pacing procedure.

If an arrhythmia is provoked by the pacing, 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. A member of the team will be by your side and talking with you at all times. 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 impulses that started it. Occasionally, the arrhythmia must be stopped by an electrical shock applied to the chest. This is called cardioversion, and would never be applied while you are awake.

You may be given some medications during the procedure. Some drugs are given to mimic your body's response to stress and activity. Some drugs are given to prevent the arrhythmias.

After the test, the catheters will be removed. Firm pressure will be applied over the puncture site for approximately 15 minutes. This is necessary to prevent any bleeding from the insertion site. You will then be taken to your hospital room, or the EP recovery area.

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 rest, you will be able to resume your previous activity level.

Postprocedural 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 temperature 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 or family members can help you eat while you are reclining in bed.

Your doctors will discuss the test results and further recommendations with you and your family members following the study.

Treatments for heart rhythm abnormalities include medications, curative catheter ablation procedures, implanted pacemakers for slow heart rhythms, and implanted anti-tachycardia devices called ICDs (Internal Cardioverter Defibrillators). There are, in addition, some surgical corrections for selected heart rhythm abnormalities.

Please make sure you understand which therapies apply to your specific heart rhythm when you discuss the options with your physicians and nurses.

If you have further questions, please feel free to contact any of the professional health care staff of the Medical Cardiology Unit or Electrophysiology Service. Our goal is to help you better understand the electrophysiology study and the treatments for heart rhythm disturbances.

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