Atrial Fibrillation and Heart Disease
Procedures for Atrial Fibrillation
When drugs do not work to correct or control atrial fibrillation, or when medications are not tolerated, a procedure may be necessary, such as: electrical cardioversion, pulmonary vein isolation, catheter ablation of the AV node, or device therapy.
What Is Electrical Cardioversion?
Electrical cardioversion frequently restores a normal rhythm, although its effect may not be permanent. After a short-acting anesthesia is given, a machine is used to deliver an electric shock through electrode patches placed on the chest to synchronize the heartbeat and restore a normal rhythm. Although this procedure only takes a few seconds, several attempts may be needed to restore a normal rhythm. A patient may need to be on Coumadin for at least three weeks before this procedure is performed. This decreases the risk of a stroke that can occur with the cardioversion.
What Is Ablation Therapy?
Catheter ablation therapy is an option for people who cannot tolerate medications or when drugs fail to maintain the normal heart rhythm.
Pulmonary vein isolation: During this procedure, special catheters are inserted into the heart. Research has shown that most atrial fibrillation signals come from the four pulmonary veins as they enter the left atrium.
A specialized viewing device called intracardiac echocardiography is used to visualize the left atrium during the procedure. One catheter in the left atrium is used to map or locate the abnormal impulses coming from the pulmonary veins. The other catheter is used to deliver the radiofrequency energy to create lesions outside the pulmonary veins. The procedure is repeated for all four pulmonary veins.
The lesions heal within four to eight weeks and form a circular scar around the pulmonary veins. The scar blocks any impulses firing from within the pulmonary veins, thereby "disconnecting" the pathway of the abnormal rhythm and curing atrial fibrillation.
Ablation of the AV node: During this procedure, the doctor applies radiofrequency energy to injure the AV node. The end result is a permanent, very slow heart rate, since the electrical impulses from the top chamber of the heart cannot travel down to the lower chamber. Therefore, the patient needs a permanent pacemaker to maintain an adequate heart rate.
What Is a Permanent Pacemaker?
A pacemaker is a device that sends electrical impulses to the heart muscle to maintain a specified heart rate. Pacemakers may be implanted in people with AF who have a slow heart rate. The pacemaker has a pulse generator (which houses the battery and a tiny computer) and leads (wires) that send impulses from the pulse generator to the heart muscle, as well as sense the heart's electrical activity.
Newer pacemakers have many sophisticated features designed to help with the management of arrhythmias and to optimize heart rate-related function as much as possible.