VT Ablation in Normal Hearts
What is Catheter Ablation?
Catheter ablation is a minimally invasive, keyhole technique used to treat a variety of heart rhythm disorders. It is performed in a special operating theatre called a cardiac catheterization laboratory, or cath lab for short. A catheter is a fine wire that can be threaded through a blood vessel via a keyhole opening in the skin and placed in the heart. Usually, a blood vessel at the top of the right thigh in the groin area is used for access to the heart.
Depending on the complexity of the arrhythmia, up to 4 catheters may be used during the procedure. Each catheter has electrodes on its end that can monitor the heart’s internal electrical activity, akin to performing an internal ECG of the heart. An ablation catheter can be used to deliver radiofrequency energy to the problem area in the heart. Radiofrequency energy is a low power, high frequency energy that is delivered to a tiny region of heart tissue near the tip of the catheter, thus cauterizing or ablating the tissue.
Radiofrequency energy has been used for decades by surgeons to cut tissue and to stop bleeding. For the treatment of heart rhythm disorders, radio-frequency energy at a much lower power is used to ablate tissue within the heart that is responsible for initiating or perpetuating your arrhythmia.
This is normally an elective procedure. You will receive a letter from the hospital bookings clerk or doctor’s secretary outlining the date, time, and other details of your hospital admission for the procedure. A nurse may call you to confirm your personal and medical details. You may need to attend a blood collection service for a blood test approximately 1 week prior to your procedure. If so, a blood test request slip will be provided.
You will receive specific instructions about any medications changes that are necessary prior to your procedure. If you are unsure about the instructions, please do contact the clinic for clarification. You will be required to fast for at least six hours before your ablation. If your procedure is in the morning, do not eat or drink after midnight, except for a sip of water to help you swallow your pills. If your procedure is in the mid to late afternoon, you may have a light, early breakfast.
You will normally be admitted on the day of your procedure. Pre-operative checks will be performed and your groin area will be shaved before transfer to the cath lab. The cath lab has a movable patient bed, an X-ray machine, ECG monitors, and other equipment.
ECG electrodes and patches will be attached to your chest and back. These will feel cool on your skin. An anaesthetist will insert a fine intravenous tube usually into the back of your hand before administering a sedative. A second tube will be placed into the artery of your wrist to monitor blood pressure. The entire ablation procedure will usually be performed under moderate sedation, or in some circumstances under general anaesthesia.
Intravenous lines will be placed in a vein at the top of the right thigh in the groin area through which catheters will be passed and positioned in the heart using X-ray or a computerized 3D mapping system for guidance. Sometimes, access to the left heart via an artery in the right groin area is also required. The catheters are used to perform electrophysiologic testing of the heart, with attempts to induce the culprit arrhythmia.
VT in structurally normal hearts is usually due to a focal source. Ablation of this form of VT is therefore also referred to as focal VT ablation. In some cases, this procedure is performed to eliminate ventricular ectopy (VE) rather than VT, but the general approach is the same. Once the culprit arrhythmia is identified, an ablation catheter is used to target the VT focus for ablation.
In some cases, the ablation catheter may need to be positioned across a thin membrane within the heart that separates the left and right heart. A transoesophageal echocardiogram (TOE) may be required to guide this process. Under general anaesthesia, the TOE probe is passed down the throat into the gullet which lies just behind the heart to provide clear pictures of the heart while access to the left heart is established. The TOE probe is removed before you wake up and may cause a self-limiting sore throat that resolves over several days.
If the source of focal VT lies close to the heart’s own blood supply, it may be necessary to perform a coronary angiogram to ensure that there is an adequate distance separating the ablation catheter tip and the critical arteries. This involves the injection of dye into the heart’s coronary arteries to define their anatomy on X-ray.
A focal VT ablation procedure typically lasts 2 to 3 hours, although it may last longer if the VT is difficult to induce or the location of the VT is in an anatomically complex region of the heart.
Focal VT ablation is a common and generally low-risk procedure. If a complication does arise, it will be dealt with at once. The risk of serious complications is 1.5% (1 to 2 in 100 chance), varying according to the location of the arrhythmia.Aside from occasional pain and bruising around the blood vessels in the right groin area, almost all patients undergoing focal VT ablation experience no complications.
The following are rare complications and may or may not be relevant to your case.
- Nerve injury and vascular damage requiring transfusion or surgical repair is very rare.
- There is a very small risk of heart attack, stroke, and cardiac bleeding.
- The need for emergency open heart surgery and death are exceedingly rare.
- There is a risk of inducing a dangerous heart rhythm that may cause dizziness and may require a small electric shock to restore normal rhythm.
If there is a chance you are pregnant, please notify the doctor performing the procedure.
After the procedure, you will return to the recovery ward before being transferred to a normal hospital ward. You will need to lie flat for 4 to 6 hours after the procedure. During this time, it is important to keep your legs straight and your head relaxed on the pillow.
It is usual to stay in hospital for 1 night after the procedure. If you required a transoesophageal echocardiogram, it is common to have a sore throat and some mild chest discomfort. You may also have some discomfort and bruising in the groin. Symptoms will typically improve over several days. You should avoid exercise, driving, and heavy lifting for 5 days after the procedure. Please arrange to take 1 week off work for your recovery.
You will need to arrange for a family member or friend to pick you up from the hospital following discharge. A follow-up appointment will be arranged 8 to 12 weeks post procedure or earlier if necessary.
- Wound care.The access site at the top of the right thigh in the groin area may take several days to heal. Observe the area every day and keep it dry and clean. Avoiding applying soap and talcum powder to the site. A pea-sized lump and a minimal amount of bruising is normal and may last for up to 2 weeks. If there is increasing pain, active bleeding, or an expanding mass in the groin, please make immediate contact with the clinic, or proceed immediately to your local emergency service for assessment.
- Rest and recovery. To facilitate healing of the access site, it is best to take a week off work, particularly if your job involves physical activity. Avoid exercise, driving, abdominal straining, and heavy lifting for 5 days. Rest and gentle walking at home is permitted. After 5 days, slowly return to normal activities. After 1 week, there should be no limitations on your usual activities.
- Contact details. Prior to your first follow-up appointment, it is best to contact the treating team for any procedure-related concerns as they will be most familiar with the details of the procedure. For public patients, contact the Alfred Heart Centre on 03 9076 3263. For private patients, contact the Heart Rhythm Clinic on 03 8560 0535. If the clinic is closed or the treating doctor or nurse not available, please proceed to your GP or local emergency service for evaluation.
Successful catheter ablation requires that your VT can be induced in the EP lab. If the VT cannot be readily induced, then it will not be possible to map the VT and accurately ablate the abnormal focus. If the VT can be induced, then the success rate depends on the location of the focus. The majority will be found in the right heart where the success rate is 90%. The success rate in other regions may be lower depending on several anatomic factors.