Cardioversion Health Article

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 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.