Catheter ablation – Purpose- Risk- Precautions

Definition
Catheter ablation of an irregular heartbeat involves having a tube (a catheter) inserted into the heart through which electrical energy is sent to either reset the heartbeat or stop the heart from beating so a mechanical pacemaker can be put in place.

Description
Catheter ablation involves delivering highly focused heat (or radio frequency energy) to specific areas of the heart. Radio frequency energy is very rapidly alternating electrical current that is produced at the tip of the catheter that is placed inside the heart.
At the same time as the catheter is inserted, a second electrode is placed on the patient’s skin. When the catheter is energized, the body conducts the energy
from the catheter’s tip, through the heart and to the electrode on the skin’s surface, completing the circuit.

Although very little electricity is given off by the catheter, the instrument does generate a largeamount of heat. This heat is absorbed by the heart tissue, causing a small localized burn and destroying the tissue in contact with the catheter tip; in this way, small regions of heart tissue are burned in a controlled manner. This controlled destruction of small sections of heart muscle actually kills the nerve cells causing the irregular heartbeat, stopping the nerve signals that are passing through this section of the heart.This usually causes the irregular heartbeat to be reset into a normal heartbeat.

Purpose
Irregular heartbeats can occur in healthy people without causing any dangerous symptoms or requiring medical attention. Slight changes in the normal patterns
of heartbeats often reset themselves without notice.
But when the heartbeat is greatly disrupted–either because of traumatic injury, disease, hypertension, surgery, or reduced blood flow to the heart caused by
blockages in the blood vessels that nourish the heart– the condition must be recognized and treated immediately. Otherwise, it can be fatal.

Various drugs can be used to control and help reset these abnormal heart rhythms (arrhythmias). The technique of catheter ablation (meaning tube-guided
removal) is used to interrupt the abnormal contractions in the heart, allowing normal heart beating to resume.
Atrial fibrillation and flutter and Wolff-Parkinson- White syndrome are two of the most common disorders treated with catheter ablation.

Precautions
The improper correction of abnormal heartbeats can cause additional arrhythmias and can be fatal.
Abnormalities in different areas of the heart cause different types of irregular heartbeats; the type ofarrhythmia must be clearly defined before this procedure
can be properly done.

Preparation
People can undergo this procedure by having general anesthesia or by taking medicines to make them relaxed and sleepy (sedatives) along with painkillers.
Once the type of irregular heartbeat is identified and these medicines are given, the catheter is inserted through a blood vessel and into the heart.
Importantly, correct placement of the catheter is visualized by using a specialized type of x-ray machine called a fluoroscope.

Aftercare
Being sure the patient is comfortable during and after this procedure is very important. However, because each person may have a different arrhythmia
and possibly other medical problems as well, each patient’s needs must be evaluated individually.

Risks
Overall, fewer than 5% of people having this procedure experience complications. The most common complications are usually related to blood vessel injury when the catheter is inserted and to different heart-related problems due to the moving of the catheter within the heart. However, in general, this technique is safe and can control many different heart arrhythmias.

Normal results
Depending upon the type of irregular heartbeat being treated, either the normal heartbeat resumes after treatment or the ability of the heart to beat on its own is lost, requiring the insertion of a pacemaker to stimulate the heart to beat regularly.

Abnormal results
Additional irregular heartbeats can occur as a result of this procedure, as can damage to the blood vessels that feed the heart. Because this procedure requires the use of the x-ray machine called a fluoroscope, there is exposure to x-ray  radiation, but it is doubtful that this is harmful in adult patients. The risk versus benefit is considered with pediatric patients.

What to Expect During Catheter Ablation
A small incision is made in the numbed skin; again, this is usually in the groin or neck area. A needle is used to puncture the blood vessel (typically a vein, but sometimes an artery) into which an ablation or diagnostic catheter, or both, will be inserted.

One or more diagnostic catheters are inserted into your blood vessel and gently moved toward the heart. Your physician will follow catheter progress on a special monitor connected to the fluoroscope camera.

Diagnostic catheters can be used to sense electrical activity in various areas of the heart and measure how fast these impulses travel. These catheters can also be used to deliver tiny electrical impulses to stimulate the heart to beat or contract. By doing so, physicians attempt to start (or induce) your tachycardia so they can understand more about it and decide how best to treat it. If you feel the same symptoms you experienced when the arrhythmia occurred previously, you should tell the electrophysiology (EP) lab staff.

Often these induced arrhythmias stop by themselves; however, if an arrhythmia persists or is very rapid, it may make you feel faint for a moment. If this happens, your doctor may need to deliver electrical therapy to the heart to stop the abnormal rhythm. If you were not in an EP lab these arrhythmias could be very dangerous, perhaps even life-threatening. The well-trained personnel in the EP lab, however, have the equipment and medications necessary to respond appropriately and immediately to these arrhythmias.

The catheter ablation procedure is usually not painful. You may feel some pressure at the sites where the catheters are inserted. It is also not unusual to experience some mild chest discomfort during the application of the high-frequency energy, which is the actual ablation part of the procedure.

Most catheter ablation procedures are completed within two hours, but a complete procedure can last up to six hours or more, which means that you may feel tired and uncomfortable after lying still for such a lengthy period of time.

 

Catheter ablation Before the procedure

Catheter ablation During the procedure

Catheter ablation After the procedure

 

Resources
ORGANIZATIONS
American Heart Association. 7320 Greenville Ave.
Dallas, TX 75231. (214) 373-6300. <http://
www.americanheart.org>.
Dominic De Bellis, PhD
Gale Encyclopedia of Medicine. Copyright 2008 The Gale Group, Inc. All rights reserved.