Ablation is performed by an electrophysiologist (EP), a doctor specializing in diagnosing and treating heart rhythm disorders.
During catheter ablation, catheters (narrow, flexible tubes) are inserted into a blood vessel, often through a site in the groin (upper thigh) or neck, and guided through the vein until they reach the heart. Small electrodes on the tip of the catheters stimulate and record the heart's activity. This test, called an electrophysiology (EP) study, allows the doctor to pinpoint the exact location of the short circuit.
Once the 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 (radio frequency energy), which cauterizes the tissue, or extremely cold, which freezes or "cryoablates" it.
Talking to your Doctor
By talking openly to your doctor, you will know what treatments are best for you. Your doctor can provide advice based upon your concerns, value and priorities; a process called shared decision-making. Even if you simply want to follow your doctor’s recommendations, it is important to have a conversation about what matters most to you.
Is an Ablation Right for You?
Ablation is used to treat many types of arrhythmias. It is often successful in eliminating the need for open-heart surgery or long-term drug therapy. Ablation may be an option in any of these cases:
- If your arrhythmia cannot be controlled with lifestyle changes or medication.
- If you cannot tolerate or do not want to take medication to treat your arrhythmia.
- If you have a supraventricular tachycardia (SVT), a rapid heartbeat that begins in the upper chambers of the heart.
- If you have ventricular tachycardia (VT), a rapid heartbeat that begins in the lower chambers of the heart. For VT, ablation is sometimes used in combination with an ICD.
What Type of Ablation is Right for Me?
There are a large variety of ablations available to patients with heart rhythm disorders.
Pulmonary Vein Isolation
The initial approach to ablation based treatment of atrial fibrillation attempts to isolate the pulmonary veins from the body of the left atrium. Electrical signals that originate between the entrance of the pulmonary vein and the left atrium have been shown to trigger atrial fibrillation. Using ablation to isolate the veins by creating a line of scar around each vein has been shown to reduce the frequency of atrial fibrillation. There are two commonly used catheter based techniques to achieve pulmonary vein isolation.
- Radiofrequency Ablation
With this technique, catheters are advanced into the left atrium from the femoral vein in the groin. Radiofrequency (RF) energy is used to heat the tissue around the pulmonary veins in a point by point fashion to create a circular scar around each vein, or around groups of veins (antral isolation). Testing is then performed to ensure that each vein is effectively isolated from the body of the left atrium. Additional lesions can be provided to treat other arrhythmias in either the right or left atrium dependent on the clinical presentation.
In this technique, a single catheter is advanced into the left atrium from the femoral vein in the groin. The tip of the catheter has a balloon that contains a refrigerant. The tip is advanced into the entrance of each vein. The balloon is then inflated, and the refrigerant is frozen. This effectively freezes the tissue that is in contact with the balloon in a circumferential fashion. In contrast to radiofrequency energy, which uses heat to create scar, cryoablation uses freezing to create scar. Electrical isolation of the pulmonary veins tested. In addition, other arrhythmias noted during the procedure may be treated using a radiofrequency catheter.
Surgical Ablation Atrial Fibrillation
A number of techniques have been developed since the initial open chest procedures for atrial fibrillation devised by Dr. James Cox in the 1980s (Cox-Maze, Cox-Maze II). This technique involved creating a myriad of scars or lesions throughout the left atrium to prevent fibrillatory conduction. Open chest procedures may be performed in association with planned coronary bypass/or cardiac valve replacement. The original "cut and sew" approaches have been supplanted with surgical ablation tools which may use radiofrequency, or cryothermal, energy sources to create scar. These techniques may be referred as Cox-Maze III-IV procedures. Several minimally invasive techniques have been devised as stand-alone procedures.
- Mini Maze
This technique utilized 3-5 small incisions along the front and side of the chest to insert special tools. Once the surgeon has accessed the surface of the heart, he/she will be able to use surgical ablation tools to perform isolation of the pulmonary veins, and treat other triggers for atrial fibrillation. The recovery from these procedures is much shorter than with open chest procedures.
This technique utilizes surgical and catheter based ablation techniques. In this technique, the electrophysiologist advances catheters into the left atrium through the femoral vein. Pulmonary vein isolation is performed using radiofrequency ablation. The cardiac surgeon then accesses the heart through a small incision underneath the sternum (breastbone) and advances a special radiofrequency catheter to deliver energy to the outside surface of the heart. In this fashion, isolation of the pulmonary veins is accomplished both from the inside and the outside surfaces of the heart.
Isolation of the pulmonary veins is considered the hallmark of atrial fibrillation ablation, and is the first line treatment for atrial fibrillation based on more than two decades of research and experience. In some selected cases, other "substrates" of atrial fibrillation may be targeted for ablation.
The left atrium is a complex structure, and individuals with persistent atrial fibrillation may have triggers independent of the pulmonary veins. Rotors are regions within the left atrium that demonstrate complex electrical activity. Recently these areas have been targeted for ablation with RF catheters and specialized mapping catheters to identify rotors. The technique may be called FIRM at some centers (Focal Impulse and Rotor Modulation).
CFAE stands for Complex Fractionated Atrial Electrograms. These CFAEs are detected by mapping systems employed in catheter ablation. These areas in the left atrium are felt to be triggers for atrial fibrillation, and may be targeted for RF ablation.
- Ganglionated Plexi
These are regions in the left atrium that are rich in autonomic innervation. Autonomic nerve fibers are involved in the human body's "flight or fight" responses, and can affect the heart rate. These regions have also been targeted for ablation with RF catheters in those patients with persistent atrial fibrillation.
In some patients, the chances for restoration of normal sinus rhythm with either catheter or surgical methods are felt to be very low. This may be due to the long standing presence of atrial fibrillation, severe other medical problems, or prior failed ablations. RF ablation of the AV node and pacemaker implantation allows regularization of the heart rate (the rapid irregular impulses of atrial fibrillation are no longer transmitted to the lower chambers or ventricles of the heart) but results in pacemaker dependence.
Catheter ablation for supraventricular tachycardia is usually accomplished utilizing radiofrequency energy. In a small number of cases, treatment may require using cryo-energy due to the proximity of the ablation site to critical structures of the normal electrical conduction system. These catheters are advanced via the femoral veins in the groin to the right and/or left atrium.
Ventricular tachycardia usually presents in the structurally abnormal heart. RF ablation has been widely utilized to treat ventricular tachycardia. In addition, there are individuals with a structurally normal heart that present with ventricular tachycardia. These arrhythmias are very amenable to treatment with RF ablation.