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Cardioversion

Cardioversion

Definition

Cardioversion refers to the process of restoring the heart's normal rhythm by applying a controlled electric shock to the exterior of the chest. Abnormal heart rhythms are called arrhythmias or dysrhythmias.


Purpose

When the heart beats too fast, blood no longer circulates effectively in the body. Cardioversion is used to stop this abnormal beating so that the heart can begin its normal rhythm and pump more efficiently.


Demographics

Cardioversion is used to treat many types of fast and/or irregular heart rhythms. Most often, cardioversion is used to treat atrial fibrillation or atrial flutter. Life-saving cardioversion can be used to treat ventricular tachycardia and ventricular fibrillation.

Abnormal heart rhythms are slightly more common in men than in women and the prevalence of abnormal heart rhythms, especially atrial fibrillation, increases with age. Atrial fibrillation is relatively uncommon in people under age 20.


Description

Elective cardioversion is usually scheduled ahead of time. After arriving at the hospital, an intravenous (IV) catheter will be placed in the arm to deliver medications and fluids. Oxygen may be given through a face mask.

In some people, a test called a transesophageal echocardiogram (TEE) may need to be performed before the cardioversion to make sure there are no blood clots in the heart.

A short-acting general anesthetic will be given through the IV to put the patient to sleep. During the five or 10 minutes of anesthesia, an electric shock is delivered through paddles or patches placed on the exterior of the chest and sometimes on the back. It may be necessary for the doctor to administer the shock two or three times to stop the abnormal heartbeat and allow the heart to resume a normal rhythm. During the procedure, the patient's breathing, blood pressure, and heart rhythm are continuously monitored.


Diagnosis/Preparation

Diagnosis of abnormal heart rhythms

A doctor may be able to detect an irregular heart beat during a physical exam by taking the patient's pulse. In addition, the diagnosis may be based upon the presence of certain symptoms, including:

  • palpitations (feeling of skipped heart beats or fluttering in the chest)
  • pounding in the chest
  • shortness of breath
  • chest discomfort
  • fainting
  • dizziness or feeling light-headed
  • weakness, fatigue, or feeling tired

Not everyone with abnormal heart rhythms will experience symptoms, so the condition may be discovered upon examination for another medical condition.

diagnostic tests. Tests used to diagnose an abnormal heart rhythm or determine its cause include:

  • blood tests
  • chest x rays
  • electrocardiogram
  • ambulatory monitors such as the Holter monitor, loop recorder and transtelephonic transmitter
  • stress test
  • echocardiogram
  • cardiac catheterization
  • electrophysiology study (EPS)
  • head-upright tilt table test
  • nuclear medicine test, such as a MUGA scan (multiple-gated acquisition scanning)

Preparation for cardioversion


medication guidelines.

  • Medication to thin the blood (blood thinner or anticoagulant) is usually given for at least three weeks before elective cardioversion.
  • The patient should take all usual medications as prescribed, unless other instructions have been given.
  • Patients who take diabetes medications or anticoagulants should ask their doctor for specific instructions.

eating and drinking guidelines. The patient should not eat or drink anything for six to eight hours before the procedure.

other guidelines. It is advisable to arrange for transportation home, because drowsiness may last several hours and driving is not permitted after the procedure.

Do not apply any lotion or ointments to your chest or back before the procedure.


Aftercare

The patient generally wakes quickly after the procedure. Medical personnel will monitor the patient's heart rhythm for a few hours, after which the patient is usually sent home. The patient should not drive home; driving is not permitted for 24 hours after the procedure.


Medications

The doctor may prescribe anti-arrhythmic medications (such as beta-blockers, digitalis, or calcium channel blockers) to prevent the abnormal heart rhythm from returning.

Some patients may be prescribed anticoagulant medication, such as warfarin and aspirin , to reduce the risk of blood clots.

The medications prescribed may be adjusted over time to determine the best dosage and type of medication so the abnormal heart rhythm is adequately controlled.


Discomfort

Some chest wall discomfort may be present for a few days after the procedure. The doctor may recommend that the patient take an over-the-counter pain reliever such as ibuprofen to relieve discomfort. Skin irritation may also be present after the procedure. Skin lotion or ointment can be used to relieve irritation.


Risks

Cardioverters have been in use for many years and the risks are few. The unlikely risks that remain include those instances when the device delivers greater or lesser power than expected or when the power setting and control knobs are not set correctly. Unfortunately, in about 50% of cases, the heart prefers its abnormal rhythm and reverts to it within one year, despite cardioversion. Cardioversion can be repeated for some patients whose abnormal heart rhythm returns.

Normal results

About 90% of cardioversions are successful and, at least for a time, restore the normal heart rhythm safely and prevent further symptoms.


Morbidity and mortality rates

The 2002 Rate Control vs. Electrical Cardioversion for Persistent Atrial Fibrillation (RACE) study, published in The New England Journal of Medicine indicated that controlling a patient's heart rate is as important as controlling the patient's heart rhythm to prevent death and complications from cardiovascular causes. The study also concluded that anticoagulant therapy is important to reduce the risk of stroke and is appropriate therapy for patients who have recurring, persistent atrial fibrillation even after they were treated with cardioversion. In patients who did not receive anticoagulant therapy after cardioversion, there was a 2.4% increase of embolic events (such as stroke or blood clots), even though there were no signs of these events prior to the procedure.


Alternatives

Atrial fibrillation and atrial flutter often revert to normal rhythms without the need for cardioversion. Healthcare providers usually try to correct the heart rhythm with medication or recommend lifestyle changes before recommending cardioversion.

Lifestyle changes often recommended to treat abnormal heart rhythms include:

  • quitting smoking
  • avoiding activities that prompt the symptoms of abnormal heart rhythms
  • limiting alcohol intake
  • limiting or not using caffeine (Caffeine products may produce more symptoms in some people with abnormal heart rhythms.)
  • avoiding medications containing stimulants, such as some cough and cold remedies (These medications contain ingredients that may cause abnormal heart rhythms. Read all medication labels and ask a doctor or pharmacist for specific recommendations.)

If cardioversion is not successful in restoring the normal heart rhythm, other treatments for abnormal heart rhythms include:

  • permanent pacemakers
  • implantable cardioverter-defibrillator
  • ablation therapy
  • heart surgery, including the Maze procedure and the pulmonary vein isolation procedure

Resources

books

McGoon, Michael D., ed., and Bernard J. Gersh, MD. Mayo Clinic Heart Book: The Ultimate Guide to Heart Health, Second Edition. New York: William Morrow and Co., Inc., 2000.

Topol, Eric J., MD. Cleveland Clinic Heart Book: The Definitive Guide for the Entire Family from the Nation's Leading Heart Center. New York: Hyperion, 2000.

Trout, Darrell, and Ellen Welch. Surviving with Heart: Taking Charge of Your Heart Care. Colorado: Fulcrum Publishing, 2002.


periodicals

The New England Journal of Medicine 347, no. 23 (December 5, 2002): 18341840.


organizations

American College of Cardiology. Heart House. 9111 Old Georgetown Rd., Bethesda, MD 20814-1699. (800) 253-4636 ext. 694 or (301) 897-5400. <http://www.acc.org>.

American Heart Association. 7272 Greenville Ave. Dallas, TX 75231. (800) 242-8721 or (214) 373-6300. <http://www.americanheart.org>.

The Cleveland Clinic Heart Center, The Cleveland Clinic Foundation. 9500 Euclid Avenue, F25, Cleveland, Ohio, 44195. (800) 223-2273 ext. 46697 or (216) 444-6697. <http://www.clevelandclinic.org/heartcenter>.

Heart Information Network. <http://www.heartinfo.org> .

HeartCenterOnline. <http://www.heartcenteronline.com> .

National Heart, Lung and Blood Institute. National Institutes of Health. Building 1. 1 Center Dr., Bethesda, MD 20892. E-mail: [email protected] <http://www.nhlbi.nih.gov>.

North American Society of Pacing and Electrophysiology. 6 Strathmore Rd., Natick, MA 01760-2499. (508) 647-0100. <http://www.naspe.org> .


Dorothy Elinor Stonely Angela M. Costello

WHO PERFORMS THE PROCEDURE AND WHERE IS IT PERFORMED?


Heart doctors (cardiologists) specially trained in cardioversion (called electrophysiologists) should perform this procedure. To find a heart rhythm specialist or an electrophysiologist, patients can contact the North American Society of Pacing and Electrophysiology. Cardioversion usually takes place in the hospital setting in a special lab called the electrophysiology (EP) laboratory. It may also be performed in an intensive care unit , recovery room or other special procedure room.

QUESTIONS TO ASK THE DOCTOR


  • Why is this procedure being performed?
  • What are the potential benefits of the procedure?
  • What are the risks of the procedure?
  • Can I take my medications the day of the procedure?
  • Can I eat or drink the day of the procedure? If not, how long before the procedure should I stop eating or drinking?
  • When can I drive after the procedure?
  • What should I wear the day of the procedure?
  • Will I be awake during the procedure?
  • What kinds of monitors are used during the procedure to evaluate my condition?
  • Will I have to stay in the hospital after the procedure?
  • When can I resume my normal activities?
  • When will I find out the results?
  • What if the procedure was not successful?
  • If I've had the cardioversion procedure once, can I have it again to correct an abnormal heart rhythm, if necessary?
  • Will I have any pain or discomfort after the procedure? If so, how can I relieve this pain or discomfort?
  • Are there any medications, foods or activities I should avoid to prevent my symptoms from recurring?

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Cardioversion

Cardioversion

Definition

Cardioversion refers to the process of restoring the heart's normal rhythm by applying a controlled electric shock to the exterior of the chest.

Purpose

When the heart beats too fast, blood no longer circulates effectively in the body. Cardioversion is used to stop this abnormal beating so that the heart can begin normal rhythm and pump more efficiently.

Precautions

Not all unusual heart rhythms (called arrhythmias ) are dangerous or fatal. Atrial fibrillation and atrial flutter often revert to normal rhythms without the need for cardioversion. Healthcare providers may also try to correct the heart rhythm with medication or recommend a lifestyle change before trying cardioversion. However, ventricular tachycardia lasting more than 30 seconds and ventricular fibrillation require immediate cardioversion.

Description

Elective cardioversion is usually scheduled ahead of time. After arriving at the hospital, an intravenous (IV) catheter will be placed in the arm and oxygen will be given through a face mask. A short-acting general anesthetic will be administered through the vein. During the two or three minutes of anesthesia, the doctor will apply two paddles to the exterior of the chest and administer the electric shock. It may be necessary to give the shock two or three times to obtain normal rhythm.

Preparation

Medication to thin the blood is usually given for at least three weeks before elective cardioversion. Food intake should be stopped eight hours before the procedure.

Aftercare

Medical personnel will monitor the heart rhythm for a few hours, after which the patient is usually sent home. It is advisable to arrange for transportation home, because drowsiness may last several hours. The doctor may prescribe anti-arrhythmic medication to prevent the abnormal rhythm from returning.

Risks

Cardioverters have been in use for many years and the risks are few. Those unlikely risks that remain include those instances when the device delivers greater or lesser power than expected or when power setting and control knobs are not set correctly. Unfortunately, in a number of cases, the heart prefers its abnormal rhythm and reverts to it despite cardioversion.

Normal results

Most cardioversions are successful and, at least for a time, restore the normal heart rhythm.

KEY TERMS

Atrial fibrillation A condition in which the upper chamber of the heart quivers instead of pumping in an organized way.

Atrial flutter A rapid pulsation of the upper chamber of the heart that interferes with normal function.

Ventricular fibrillation A condition in which the lower chamber of the heart quivers instead of pumping in an organized way.

Ventricular tachycardia A rapid heart beat, usually over 100 beats per minute.

Resources

ORGANIZATIONS

American Heart Association. 7320 Greenville Ave. Dallas, TX 75231. (214) 373-6300. <http://www.americanheart.org>.

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cardioversion

cardioversion (countershock) (kar-di-oh-ver-shŏn) n. restoration of normal heart rhythm in patients with increased heart rate caused by arrhythmia. It involves the application of a controlled shock through electrodes placed on the chest wall of the anaesthetized patient. The apparatus is called a cardiovertor.

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Cardioversion

Cardioversion

Definition

Cardioversion refers to the process of restoring the heart's normal rhythm by applying a controlled electric shock to the exterior of the chest.

Purpose

When the heart beats too fast, blood no longer circulates effectively in the body. Cardioversion is used to stop this abnormal beating so that the heart can begin normal rhythm and pump more efficiently.

KEY TERMS

Atrial fibrillation —A condition in which the upper chamber of the heart quivers instead of pumping in an organized way.

Atrial flutter —A rapid pulsation of the upper chamber of the heart that interferes with normal function.

Ventricular fibrillation —A condition in which the lower chamber of the heart quivers instead of pumping in an organized way.

Ventricular tachycardia —A rapid heart beat, usually over 100 beats per minute.

Precautions

Not all unusual heart rhythms (called arrhythmias ) are dangerous or fatal. Atrial fibrillation and atrial flutter often revert to normal rhythms without the need for cardioversion. Healthcare providers may also try to correct the heart rhythm with medication or recommend a lifestyle change before trying cardioversion. However, ventricular tachycardia lasting more than 30 seconds and ventricular fibrillation require immediate cardioversion.

Description

Elective cardioversion is usually scheduled ahead of time. After arriving at the hospital, an intravenous (IV) catheter will be placed in the arm and oxygen will be given through a face mask. A short-acting general anesthetic will be administered through the vein. During the two or three minutes of anesthesia, the doctor will apply two paddles to the exterior of the chest and administer the electric shock. It may be necessary to give the shock two or three times to obtain normal rhythm.

Preparation

Medication to thin the blood is usually given for at least three weeks before elective cardioversion. Food intake should be stopped eight hours before the procedure.

Aftercare

Medical personnel will monitor the heart rhythm for a few hours, after which the patient is usually sent home. It is advisable to arrange for transportation home, because drowsiness may last several hours. The doctor may prescribe anti-arrhythmic medication to prevent the abnormal rhythm from returning.

Risks

Cardioverters have been in use for many years and the risks are few. Those unlikely risks that remain include those instances when the device delivers greater or lesser power than expected or when power setting and control knobs are not set correctly. Unfortunately, in a number of cases, the heart prefers its abnormal rhythm and reverts to it despite cardioversion.

Results

Most cardioversions are successful and, at least for a time, restore the normal heart rhythm.

Resources

ORGANIZATIONS

American Heart Association. 7320 Greenville Ave. Dallas, TX 75231. (214) 373-6300. http://www.americanheart.org.

Dorothy Elinor Stonely

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Because each style has its own formatting nuances that evolve over time and not all information is available for every reference entry or article, Encyclopedia.com cannot guarantee each citation it generates. Therefore, it’s best to use Encyclopedia.com citations as a starting point before checking the style against your school or publication’s requirements and the most-recent information available at these sites:

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Notes:
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  • In addition to the MLA, Chicago, and APA styles, your school, university, publication, or institution may have its own requirements for citations. Therefore, be sure to refer to those guidelines when editing your bibliography or works cited list.

Cardioversion

Cardioversion

Definition
Purpose
Demographics
Description
Diagnosis/Preparation
Aftercare
Risks
Normal results
Morbidity and mortality rates
Alternatives

Definition

Cardioversion refers to the process of restoring the heart’s normal rhythm either by applying a controlled electric shock to the exterior of the chest or by giving certain medications. The first type is called synchronized electrical cardioversion; the second is called pharmacologic or chemical cardioversion. Abnormal heart rhythms are called arrhythmias or dysrhythmias.

Purpose

When the heart beats too fast, blood no longer circulates effectively in the body. Cardioversion is used to stop this abnormal beating so that the heart can begin its normal rhythm and pump more efficiently.

Demographics

Cardioversion is used to treat many types of fast and/or irregular heart rhythms. Most often, cardioversion is used to treat atrial fibrillation or atrial flutter. Life-saving cardioversion can be used to treat ventricular tachycardia and ventricular fibrillation; implantable cardioverter-defibrillators (ICDs) are designed to treat these two conditions.

Abnormal heart rhythms are slightly more common in men than in women and the prevalence of abnormal heart rhythms, especially atrial fibrillation, increases with age. Atrial fibrillation is relatively uncommon in people under age 20 but affects 5% of the American population over 65, and 8% of the population over 80. It is responsible for 15-25% of all strokes.

Description

Synchronized electrical cardioversion

Elective synchronized electrical cardioversion is usually scheduled ahead of time. After arriving at the hospital, the patient will have an intravenous (IV) catheter placed in the arm to deliver medications and fluids. Oxygen may be given through a face mask.

In some people, a test called a transesophageal echocardiogram (TEE) may need to be performed before the cardioversion to make sure there are no blood clots in the heart.

A short-acting general anesthetic will be given through the IV to put the patient to sleep. During the

five or 10 minutes of anesthesia, an electric shock is delivered through paddles or patches placed on the exterior of the chest and sometimes on the back. It may be necessary for the doctor to administer the shock two or three times to stop the abnormal heartbeat and allow the heart to resume a normal rhythm. During the procedure, the patient’s breathing, blood pressure, and heart rhythm are continuously monitored.

Pharmacologic cardioversion

Pharmacologic, or chemical, cardioversion is a less immediate method of restoring normal hear rhythm, and is somewhat less effective than electrical cardioversion, having a success rate between 60% and 80%. It has the advantage of being simpler and more convenient, particularly for patients who are afraid of electrical devices. The patient does not need to undergo anesthesia and can receive the drugs immediately after eating; there is no need to fast for several hours.

There are two basic groups of drugs given in pharmacologic cardioversion: those given to control the heart rate and those given to normalize the heart rhythm. The first group includes such medications as digoxin (Lanoxin), diltiazem (Cardizem), verapamil (Calan), esmolol (Brevibloc), metoprolol (Lopressor), and propranolol (Inderal). These drugs may be given either intravenously or orally. With the exception of digoxin, which takes about 30 minutes to take effect, these drugs begin to work in 5-7 minutes.

Drugs given to normalize the heart rhythm are called antiarrhythmics. Quinidine (Quinaglute), the oldest drug in this group, is given by mouth, while procai-namide, propafenone (Rythmol), flecainide (Tambocor), amiodarone (Cordarone), sotalol (Betapace), dofetilide (Tikosyn) and ibutilide (Corvert) may be given intravenously or orally. Unlike the drugs given to control the heart rate, these medications take longer to work, one hour for procainamide and ibutilide, and 3–8 hours for the others. These drugs should be administered in a hospital setting where the patient can be monitored. Dofetilide can be prescribed only by physicians who have had special training in the risks and side effects of the drug.

Diagnosis/Preparation

Diagnosis of abnormal heart rhythms

A doctor may be able to detect an irregular heart beat during a physical exam by taking the patient’s pulse. In addition, the diagnosis may be based upon the presence of certain symptoms, including:

  • palpitations (feeling of skipped heart beats or fluttering in the chest)
  • pounding in the chest
  • shortness of breath
  • chest discomfort
  • fainting
  • dizziness or feeling light-headed
  • weakness or fatigue

Not everyone with abnormal heart rhythms will experience symptoms, so the condition may be discovered upon examination for another medical condition.

DIAGNOSTIC TESTS. Tests used to diagnose an abnormal heart rhythm or determine its cause include:

  • blood tests
  • chest x rays
  • electrocardiogram
  • ambulatory monitors such as the Holter monitor, loop recorder, and transtelephonic transmitter
  • stress test
  • echocardiogram
  • cardiac catheterization
  • electrophysiology study (EPS)
  • head-upright tilt table test
  • nuclear medicine test, such as a MUGA scan(multiple-gated acquisition)

Preparation for synchronized electrical cardioversion

Medication to thin the blood (blood thinner or anticoagulant) is usually given for at least three weeks before elective cardioversion. The patient should take all usual medications as prescribed, unless other instructions have been given. Patients who take diabetes medications or anticoagulants should ask their doctor for specific instructions.

The patient should not eat or drink anything for six to eight hours before the procedure.

It is advisable to arrange for transportation home, because drowsiness may last several hours and driving is not permitted after the procedure. The patient is also advised not to apply any lotion or ointments to the chest or back before the procedure.

Aftercare

The patient generally wakes quickly after the procedure. Medical personnel will monitor the patient’s heart rhythm for a few hours, after which the patient is usually sent home. The patient should not drive home; driving is not permitted for 24 hours after the procedure.

Medications

The doctor may prescribe anti-arrhythmic medications (such as beta-blockers, digitalis, or calcium channel blockers) to prevent the abnormal heart rhythm from returning.

Some patients may be prescribed anticoagulant medication, such as warfarin and aspirin, to reduce the risk of blood clots.

The medications prescribed may be adjusted over time to determine the best dosage and type of medication so the abnormal heart rhythm is adequately controlled.

Discomfort

Some chest wall discomfort may be present for a few days after the procedure. The doctor may recommend that the patient take an over-the-counter pain reliever such as ibuprofen to relieve discomfort. Skin irritation may also be present after the procedure. Skin lotion or ointment can be used to relieve irritation.

Risks

Cardioverters have been in use for many years and the risks are few. The unlikely risks that remain include those instances when the device delivers greater or lesser power than expected or when the power setting and control knobs are not set correctly. Unfortunately, in about 50% of cases, the heart prefers its abnormal rhythm and reverts to it within one year, despite cardioversion. Cardioversion can be repeated for some patients whose abnormal heart rhythm returns.

Normal results

About 90% of cardioversions are successful and, at least for a time, restore the normal heart rhythm safely and prevent further symptoms.

KEY TERMS

Ablation— The removal or destruction of tissue.

Ablation therapy— A procedure used to treat arrhythmias, especially atrial fibrillation. During the procedure, a catheter (small flexible tube) is inserted in a vein and threaded to the heart. High-frequency electrical energy is delivered through the catheter to disconnect the pathway causing the abnormal heart rhythm in the heart.

Ambulatory monitors— Small portable electrocardiograph machines that record the heart’s rhythm. Ambulatory monitors include the Holter monitor, loop recorder, and transtelephonic transmitter. Each type of monitor has specific features related to the length of recording time and the ability to send the recordings over the phone.

Antiarrhythmic— Medication used to treat abnormal heart rhythms.

Anticoagulant— A medication, also called a “blood thinner,” that prevents blood from clotting. This type of medication is used for people at risk of stroke or blood clots.

Arrhythmia— An irregular heart rhythm.

Atria (singular, atrium)— The right and left upper chambers of the heart.

Atrial fibrillation— A condition in which the upper chamber of the heart quivers instead of pumping in an organized way.

Atrial flutter— A rapid pulsation of the upper chambers of the heart that interferes with normal heart function. Atrial flutter is usually more organized and regular than atrial fibrillation, although it often converts to atrial fibrillation. Atrial flutter occurs most often in people with heart disease and in the first week after heart surgery.

Cardiac catheterization— An invasive procedure used to create x-ray images of the coronary arteries, heart chambers and valves. During the procedure, a catheter is inserted into an artery in the groin or arm and is guided to the heart. Contrast material (dye) is injected into the catheter to produce the x ray images.

Echocardiogram— An imaging procedure used to create a picture of the heart’s movement, valves and chambers. The test uses high-frequency sound waves that come from a hand wand placed on the chest. Echocardiogram may be used in combination with Doppler ultrasound to evaluate the blood flow across the heart’s valves.

Electrocardiogram (ECG, EKG)— A test that records the electrical activity of the heart using small electrode patches attached to the skin on the chest.

Electrophysiology study (EPS)— A test that evaluates the electrical activity within the heart. The test is used to help determine the cause of the abnormal heart rhythm and find the best treatment. During the test, the doctor may safely reproduce the abnormal heart rhythm and give the patient medications to determine which medication works best to control the abnormal heart rhythm.

Head-upright tilt table test— A test used to determine the cause of fainting spells. During the test, the patient is tilted at different angles on special table for a period time. During the test, the patient’s heart rhythm, blood pressure and other measurements are evaluated with changes in position.

Implantable cardioverter-defibrillator (ICD)— Anelectronic device that is surgically placed to constantly monitor the patient’s heart rate and rhythm. If a very fast abnormal heart rate is detected, the device delivers electrical energy to the heart to beat in a normal rhythm again.

Maze procedure— A surgical procedure used to treat atrial fibrillation. During the procedure, precise incisions are made in the right and left atria to interrupt the conduction of abnormal impulses. When the heart heals, scar tissue forms and the abnormal electrical impulses are blocked from traveling through the heart.

Nuclear imaging— Method of producing images by detecting radiation from different parts of the body after a radioactive tracer material is administered.

Pacemaker— A small electronic device implanted under the skin. This device sends electrical impulses to the heart to maintain a suitable heart rate and prevent slow heart rates.

Pharmacologic cardioversion— The use of medications to restore normal heart rhythm. It is also called chemical cardioversion.

Pulmonary vein isolation— A surgical procedure used to treat atrial fibrillation. During the procedure, a radio frequency probe, microwave probe, or cryoprobe is inserted and, under direct vision, used to create lesion lines in the heart to interrupt the conduction of abnormal impulses.

Stress test— A test used to determine how the heart responds to stress. It usually involves walking on a treadmill or riding a stationary bike at increasing levels of difficulty, while the electrocardiogram, heart rate and blood pressure are monitored. If the patient is unable to walk on a treadmill or ride a stationary bike, medications may be used to produce similar results.

Synchronized electrical cardioversion— The term used to describe cardioversion by the application of a controlled electric shock to the patient’s chest.

Transesophageal echocardiogram (TEE)— An invasive imaging procedure used to create a picture of the heart’s movement, valves, and chambers. The test uses high-frequency sound waves that come from a small transducer passed down the patient’s throat. TEE may be used in combination with Doppler ultrasound to evaluate the blood flow across the heart’s valves.

Ventricles— The lower, pumping chambers of the heart. The heart has two ventricles: the right and the left ventricle.

Ventricular fibrillation— An erratic, disorganized firing of impulses from the ventricles, the lower chambers of the heart. The ventricles quiver instead of pumping in an organized way, preventing blood from pumping through the body. Ventricular fibrillation is a medical emergency that must be treated with cardiopulmonary resuscitation (CPR) and defibrillation as soon as possible.

Ventricular tachycardia— A rapid heart beat, usually over 100 beats per minute. Ventricular tachycardia originates from the lower chambers of the heart (ventricles). The rapid rate prevents the heart from filling adequately with blood, so less blood is able to pump through the body. Ventricular tachycardia can be a serious type of arrhythmia and may be associated with more symptoms.

Morbidity and mortality rates

Controlling a patient’s heart rate is as important as controlling the patient’s heart rhythm to prevent death and complications from cardiovascular causes. Anticoagulant therapy is important to reduce the risk of stroke and is appropriate therapy for patients who have recurring, persistent atrial fibrillation even after they were treated with cardioversion. In patients who did not receive anticoagulant therapy after cardioversion, there was a reported 2.4% increase of embolic events (such as stroke or blood clots), even though there were no signs of these events prior to the procedure.

Alternatives

Atrial fibrillation and atrial flutter often revert to normal rhythms without the need for cardioversion. Healthcare providers usually try to correct the heart rhythm with medication or recommend lifestyle changes before recommending electrical cardioversion.

Lifestyle changes often recommended to treat abnormal heart rhythms include:

  • quitting smoking
  • avoiding activities that prompt the symptoms of abnormal heart rhythms
  • limiting alcohol intake
  • limiting or not using caffeine (caffeine products may produce more symptoms in some people with abnormal heart rhythms)
  • avoiding medications containing stimulants, such as some cough and cold remedies (these medications contain ingredients that may cause abnormal heart rhythms)

If cardioversion is not successful in restoring the normal heart rhythm, other treatments for abnormal heart rhythms are considered. These include an implantable cardioverter-defibrillator (ICD). Since first approved by the Food and Drug Administration (FDA) in 1985, ICDs have been continually improved. Current models are much smaller and easier to implant than the early ICDs, can be programmed to deliver low-energy or high-energy shocks, and have batteries that last as long as six years. Originally considered a treatment of last resort, ICDs are now considered first-line therapy for some abnormal heart rhythms. The chief drawback of ICDs is the anxiety some patients feel about the possibility of the device’s firing (emitting a shock).

Other treatments for abnormal heart rhythms include permanent pacemakers, ablation therapy, and heart surgery, including the Maze procedure and the pulmonary vein isolation procedure.

WHO PERFORMS THE PROCEDURE AND WHERE IS IT PERFORMED?

Heart doctors (cardiologists) specially trained in cardioversion (called electrophysiologists) should perform this procedure. To find a heart rhythm specialist or an electrophysiologist, patients can contact the Heart Rhythm Society (formerly the North American Society of Pacing and Electrophysiology). Cardioversion usually takes place in the hospital setting in a special lab called the electrophysiology (EP) laboratory. It may also be performed in an intensive care unit, recovery room or other special procedure room.

Resources

BOOKS

Elefteriades, John A., and Lawrence S. Cohen. Your Heart: An Owner’s Guide: Answers to Your Questions about Heart Disease. Amherst, NY: Prometheus Books, 2007.

McGoon, Michael D., ed., and Bernard J. Gersh, MD. Mayo Clinic Heart Book: The Ultimate Guide to Heart Health, Second Edition. New York: William Morrow and Co., Inc., 2000.

Topol, Eric J., ed. Textbook of Cardiovascular Medicine, 3rd ed. Philadelphia: Lippincott Williams and Wilkins, 2007.

Trout, Darrell, and Ellen Welch. Surviving with Heart: Taking Charge of Your Heart Care. Golden, CO: Fulcrum Publishing, 2002.

PERIODICALS

American College of Cardiology, American Heart Association, and the European Society of Cardiology. “ACC/ AHA/ESC 2006 Guidelines for the Management of Patients with Atrial Fibrillation: Full Text.” Europace 8 (September 2006): 651–745.

Bostwick, J. M., and C. L. Sola. “An Updated Review of Implantable Cardioverter/Defibrillators, Induced Anxiety, and Quality of Life.” Psychiatric Clinics of North America 30 (December 2007): 677–688.

Cotiga, D., A. Arshad, E. Aziz, et al. “Acute Conversion of Persistent Atrial Fibrillation during Dofetilide Initiation.” Pacing and Clinical Electrophysiology 30 (December 2007): 1527–1530.

Khan, Ijaz A. “Pharmacological Cardioversion of Recent-Onset Atrial Fibrillation.” European Heart Journal 25, no. 15(2004): 1274–1276.

London, B. “Amiodarone and Atrial Fibrillation.” Journal of Cardiovascular Electrophysiology 18 (December 2007): 1321–1322.

QUESTIONS TO ASK THE DOCTOR

  • Why is this procedure being performed?
  • What are the potential benefits of the procedure?
  • What are the risks of the procedure?
  • Can I take my medications the day of the procedure?
  • Can I eat or drink the day of the procedure? If not, how long before the procedure should I stop eating or drinking?
  • When can I drive after the procedure?
  • What should I wear the day of the procedure?
  • Will I be awake during the procedure?
  • What kinds of monitors are used during the procedure to evaluate my condition?
  • Will I have to stay in the hospital after the procedure?
  • When can I resume my normal activities?
  • When will I find out the results?
  • What if the procedure was not successful?
  • If I have had the cardioversion procedure once, can I have it again to correct an abnormal heart rhythm, if necessary?
  • Will I have any pain or discomfort after the procedure? If so, how can I relieve this pain or discomfort?
  • Are there any medications, foods or activities I should avoid to prevent my symptoms from recurring?
  • Is an ICD suitable for my condition?

Miller, Karl E. “Amiodarone for Cardioversion on Recent-Onset Atrial Fibrillation.” American Family Physician 68 (July 15, 2003): 355.

ORGANIZATIONS

American College of Cardiology. Heart House, 2400 N Street, NW, Washington, DC 20037. (202) 375-6000. http://www.acc.org (accessed March 8, 2008).

American Heart Association (AHA). 7272 Greenville Ave. Dallas, TX 75231. (800) 242-8721 or (214) 373-6300. http://www.americanheart.org (accessed March 8, 2008).

Cleveland Clinic Heart and Vascular Institute, The Cleveland Clinic Foundation. 9500 Euclid Avenue, F25, Cleveland, Ohio, 44195. (216) 445-9288. http://www.clevelandclinic.org/heartcenter (accessed March 8, 2008).

HeartCenterOnline. http://www.heartcenteronline.com (accessed March 8, 2008).

Heart Rhythm Society (HRS). 1400 K Street NW, Suite 500, Washington, DC 20005. (202) 464-3400. http://www.hrsonline.org/ (accessed March 8, 2008).

National Heart, Lung and Blood Institute (NHLBI). NHLBI Health Information Center, P.O. Box 30105, Bethesda, MD 20824-0105. (301) 592-8573. http://www.nhlbi.nih.gov (accessed March 8, 2008).

OTHER

Beyerbach, Daniel M. “Implantable Cardioverter-Defibrillators.” eMedicine, September 6, 2006. http://www.emedicine.com/med/topic3386.htm (accessed January 8, 20080.

Chauhan, Vijai V., and Antonella Quattromani. “Synchronized Electrical Cardioversion.” eMedicine, July 18, 2006. http://www.emedicine.com/med/topic2968.htm (accessed January 8, 2008).

Dorothy Elinor Stonely

Angela M. Costello

Rebecca Frey, PhD

Carotid artery stenting see Endovascular stent surgery

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