Treatments for Heart Arrhythmiaby Roger S. Blumenthal, M.D.
Arrhythmias are treated in a number of ways. In many individuals, medication is helpful, although these drugs can have serious side effects. Electrical cardioversion—the administration of an electrical stimulus to the heart to restore its normal rhythm—is the only way to overcome ventricular fibrillation, and it may also be used to treat atrial fibrillation. In addition, an increasing number of arrhythmias are treated with radiofrequency catheter ablation or with an implanted device such as a pacemaker or cardioverter-defibrillator.
Drugs are used to suppress abnormal activity where the arrhythmia originates or to block the conduction of abnormal electrical impulses. For example, atrial fibrillation can be treated by either slowing the ventricular heart rate or trying to return the rhythm to normal. Beta-blockers, such as metoprolol (Lopressor, Toprol XL) and propranolol, and calcium-channel blockers such as diltiazem (Cardizem) and verapamil (Calan), are frequently used to slow the heart rate. These drugs slow the conduction of electrical impulses through the AV node (the relay station between the atria and ventricles) and reduce the response of the ventricles to the rapid rhythm of the atria.
Anti-arrhythmic medications, such as ibutilide (Corvert), procainamide, sotalol (Betapace, Sorine), amiodarone (Cordarone, Nexterone, Pacerone), flecainide (Tambocor), and propafenone (Rythmol), may be used to try to convert atrial fibrillation to a normal rhythm. These anti-arrhythmic medications can have potentially serious adverse effects—for example, bradycardia (slow heart rate) and hypothyroidism (a deficiency in thyroid hormone production).
When drug therapy fails in people with atrial fibrillation, electrical cardioversion may be tried to return the heart rhythm to normal. After administration of an intravenous sedative, the heart is given an electrical shock that interrupts its electrical activity and may restore it to a normal rhythm.
Electrical cardioversion is the only effective treatment for ventricular fibrillation. Now that portable automated external defibrillators are available in public places like malls, stadiums, and airports, lifesaving electrical cardioversion can be delivered not only by emergency personnel but also by anyone who witnesses a cardiac arrest. In a recent study, the use of an automated external defibrillator before emergency services arrived nearly doubled survival after a cardiac arrest.
Artificial pacemakers are small devices surgically implanted within the chest. Leads from the pacemaker to the heart provide electrical stimuli to maintain the heart rate in individuals with bradycardia or disorders of the AV node. When the heart is beating too slowly, the pacemaker detects the problem and stimulates the heart rate to a normal level.
Implantable cardioverter-defibrillator (ICD): part 1
An ICD can stop a life-threatening ventricular arrhythmia. It is recommended for people who have survived a cardiac arrest due to ventricular fibrillation, experienced other life-threatening ventricular arrhythmias, or are at high risk for ventricular arrhythmias because they have had a heart attack that severely affected the function of the heart’s left ventricle.
Implantable cardioverter-defibrillator (ICD): part 2
An ICD constantly monitors the heart’s rhythm. When it detects a dangerous rhythm, it delivers an electrical shock to return the heart to its normal rhythm. The shocks can be startling and painful, but the discomfort lasts only a short time. Implantation of an ICD generally requires a two- to three-day stay in the hospital so that doctors can test the device. Most ICDs also have a pacemaker component so that a single device can be used to treat people who have more than one type of arrhythmia.
Radiofrequency catheter ablation: part 1
This type of ablation is an increasingly popular method of suppressing tachycardias that originate in the atria, such as atrial fibrillation. Ablation is also sometimes used for ventricular tachycardias. The effectiveness of this technique is high (up to a 90 percent success rate) in people with certain types of tachycardia. The risks are minimal, although bleeding or infection can occur.
Radiofrequency catheter ablation: part 2
The procedure requires an electrophysiological study to identify the area of the heart responsible for the abnormal rhythm. Then with the patient mildly sedated, the doctor inserts a catheter (often into a vein in the groin) and guides it to the site in the heart causing the rhythm disturbance. The abnormal tissue is then ablated (destroyed) using radiofrequency energy delivered through a heated electrode at the tip of the catheter.