Other Ablation

Catheter ablation is a procedure where one or more flexible, thin tubes (catheters) are guided via x-ray into the blood vessels and directed to the heart muscle. A burst of radiofrequency energy destroys very small areas of tissue that give rise to abnormal electrical signals.

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 is usually hot (radiofrequency energy), which cauterizes the tissue, or occasionally 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.

Normally, electricity flows throughout the heart in a regular, measured pattern. This electrical system brings about heart muscle contractions. A problem anywhere along the electrical pathway causes an arrhythmia, or heart rhythm disturbance. By accurately diagnosing the precise cause of an arrhythmia, it is possible to select the best possible treatment.

Why an EP study?

While electrocardiograms (ECGs) are important tests of the heart’s electrical system, they are brief tests that record only the events that occur while the tests are running. Arrhythmias, by their very nature, are unpredictable and intermittent, which makes it unlikely that an ECG or electrocardiogram will capture the underlying electrical pathway problem. Even tests that stretch over longer time lengths, such as Holter monitoring, may not capture an event.

During an EP study, a specially trained cardiac specialist may provoke arrhythmia events and collect data about the flow of electricity during actual events. As a result, EP studies can help locate the specific areas heart tissue that give rise to the abnormal electrical impulses that cause arrhythmias. This detailed electrical flow information provides valuable diagnostic and, therefore, treatment information.

The value of an EP study

An electrophysiologic, or EP, study provides information that is key to diagnosing and treating arrhythmias. EP studies most often are recommended for patients with symptoms indicative of heart rhythm disorders or for people who may be at risk for Sudden Cardiac Death. Although it is more invasive than an electrocardiogram (ECG) or echocardiogram, and involves provoking arrhythmias, the test produces data that makes it possible to:

• Diagnose the source of arrhythmia symptoms
• Evaluate the effectiveness of certain medications in controlling the heart rhythm disorder
• Predict the risk of a future cardiac event, such as sudden cardiac death
• Assess the need for an implantable device (a pacemaker or ICD) or treatment procedure (radio frequency catheter ablation)

An Overview of the Procedure

While ECGs are non-invasive, an EP study is invasive. The study is performed after giving local anesthesia and conscious sedation (twilight sleep) to keep the patient as comfortable as possible. The procedure involves inserting a catheter – a narrow, flexible tube – attached to electricity monitoring electrodes, into a blood vessel, often through a site in the groin or neck, and winding the catheter wire up into the heart. The journey from entry point to heart muscle is navigated by images created by a fluoroscope, an x-ray-like machine that provides continuous, “live” images of the catheter and heart muscle. Once the catheter reaches the heart, electrodes at its tip gather data and a variety of electrical measurements are made. These data pinpoint the location of the faulty electrical site. During this “electrical mapping,” the cardiac arrhythmia specialist may instigate, through pacing (the use of tiny electrical impulses), some of the very arrhythmias that are the crux of the problem. The events are safe, given the range of experts and resources close at hand and are necessary to ensure the precise location of the problematic tissue.

Once the damaged site or sites are confirmed, the specialist may administer different medications or electrical impulses to determine their ability to halt the arrhythmia and restore normal heart rhythm. Based on this data, as well as information acquired before the study, sometimes the specialist will proceed to place an implantable cardioverter device (ICD) or a pacemaker or will perform cardiac ablation. In any case, the information proves useful for diagnosis and treatment.

Throughout the procedure, the patient is sedated but awake and remains still. Patients rarely report pain, more often describing what they feel as discomfort. Some are able to watch the procedure on monitors and occasionally ask questions. Others sleep. The procedure usually takes about two hours. The patient remains still for four to six hours afterward to ensure the entry point incision begins to heal properly. Once mobile again, patients may feel stiff and achy from lying still for hours.

Who Performs the Test and Where

A cardiac electrophysiologist, with advanced training in the diagnosis and treatment of heart rhythm problems, performs the EP study. The cardiac electrophysiologist leads a team of specially trained health care professionals, technicians and nurses, who assist during the procedure. The team performs the EP study in an electrophysiology laboratory, or EP lab, a well-equipped, controlled clinical environment usually located within a hospital or clinic. As a result, the test is quite safe and complications are rare.

What is Ablation?

Results

Cardiac ablation is an effective treatment, and the treatment of first choice 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).

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.