Your rhythmic heartbeat is controlled by a smooth, constant flow of electricity through the heart. A short-circuit anywhere along this electrical pathway can disrupt the normal flow of signals, causing an arrhythmia (an irregular heartbeat). Cardiac ablation is a procedure used either to destroy these short-circuits and restore normal rhythm, or to block damaged electrical pathways from sending faulty signals to the rest of the heart.
What to Expect During the Procedure
Cardiac ablation is performed by a cardiac electrophysiologist — a physician who specializes in diagnosing and treating heart rhythm disorders. The procedure involves inserting catheters — narrow, flexible tubes — into a blood vessel, often through a site in your groin or neck, and threading them through the vein until they reach your heart. You will be given sedatives to make you relaxed and comfortable, and a topical anesthetic to numb your skin before the catheters are inserted.
Using electrodes on the tip of the catheters, the doctor first conducts an electrophysiology (EP) study to pinpoint the location of the short-circuit. Once the precise location is confirmed, the “short-circuit” is either destroyed (to reopen the electrical pathway) or blocked (to prevent it from sending faulty signals to the rest of the heart). This is done by sending energy through the catheters to destroy a small amount of tissue at the site. The energy may be either hot (radiofrequency energy), which cauterizes the tissue, or extremely cold, which freezes or “cryoablates” it.
Most people say they experience only brief moments of discomfort, rather than pain, during the procedure. As with an EP study, you will need to lie still for four to six hours afterward to make sure your catheter incision starts healing properly.
Results
Cardiac ablation is an effective treatment for many types of arrhythmias. It is successful in 90 to 98 percent of cases, eliminating the need for open-heart surgery or long-term drug therapy.
Is Ablation Right for You?
Cardiac ablation may be an option in any of these cases:
- If your arrhythmia can’t be controlled with lifestyle changes or medication.
- If you can’t tolerate or don’t want to take the drugs used to treat your arrhythmia.
- If you have a supraventricular tachycardia (SVT) — a rapid heartbeat that begins in the upper chambers of the heart.
- (Less commonly) if you have ventricular tachycardia (VT), an arrhythmia that begins in the lower chambers. For VT, ablation is sometimes coupled with an ICD (implantable cardioverter defibrillator).
Atrial Fibrillation Ablation
- Pulmonary vein atrium isolation: Research has shown that most atrial fibrillation signals come from the four pulmonary veins. During this procedure, special catheters are inserted into the heart. Two catheters are inserted into the right atrium and two into 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 and within 4 to 8 weeks, 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.
Atrial Flutter Ablation
This is an arrhythmia caused by one or more rapid circuits in the atrium. Atrial flutter ablation is done by applying energy to a structure in the right atrium called the isthmus to stop conduction through this structure.
Other Types of Ablation Therapies
- Radiofrequency ablation: A special radiofrequency energy catheter is used to heat the tissue and produce lesions on the heart similar to the lesions of the Maze procedure. There are a variety of surgical techniques related to the type of catheter used, the dose of energy, and the types of lesions created.
- Cryothermy: (also called cryoablation) Very cold temperatures are transmitted through a probe (called a cryoprobe) to create lesions. This technique is used commonly during arrhythmia surgery to replace the incisions made during the Cox Maze procedure. This is also used for catheter “cryo” ablation.
- Microwave technology: A special wand-like catheter is used to direct microwave energy to create several lesions on the heart. The lesions block the conduction of abnormal electrical beats and restore a normal heartbeat.
- Laser: Lasers rapidly create the lesions or lines of conduction block. Laser technology offers promise for the development of additional minimally invasive approaches.
- Surgical ablation: Procedures used for treating atrial fibrillation can be "minimally invasive" or traditional "open" surgery and may be combined with other surgical therapies such as bypass surgery, valve repair, or valve replacement. Surgical ablation procedures include:
- The Maze procedure. During this traditional open-heart surgical procedure, the surgeon makes small cuts in the heart to interrupt the conduction of abnormal impulses and to direct normal sinus impulses to travel to the atrioventricular node (AV node) as they normally should. When the heart heals, scar tissue forms and the abnormal electrical impulses are blocked from traveling through the heart.
- Minimally invasive surgical ablation. Unlike traditional heart surgery, there is no large chest wall incision and the heart is not stopped. These techniques utilize smaller incisions and endoscopes (small, lighted instruments that contain a camera).
- The modified Maze procedure. The surgeon uses a special catheter to deliver energy that creates controlled lesions on the heart and ultimately scar tissue. This scar tissue blocks the abnormal electrical impulses from being conducted through the heart and promotes the normal conduction of impulses through the proper pathway. One of four energy sources may be used to create the scars: radiofrequency, microwave, laser or cryothermy (cold temperatures). The modified Maze procedure involves a single incision in the left atrium.
