AV Node Ablation
What is AV node ablation?
AV node ablation is a catheter-based treatment aimed at relieving troublesome symptoms of AF where all other therapies have been ineffective or unsuitable.Before the procedure, a permanent cardiac pacemaker needs to be implanted first. This device will regulate the heart’s rhythm once the ablation has been performed.
The AV node is a critical structure in the centre of the heart that relays electrical impulses from the atria to the ventricles. The ventricles are the main pumping chambers of the heart and rely on these electrical impulses to beat regularly and to generate your pulse.
In AF, the AV node is severely overstimulated, and the ventricles are made to pump rapidly and erratically. AV node ablation blocks the electrical connection between the atria and ventricles, allowing the pacemaker to regulate your heart rhythm even while AF continues in the upper chambers.
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.
The catheter has electrodes on its end that can monitor the heart’s internal electrical activity, akin to performing an internal ECG of the heart. It 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 or early afternoon, 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. The entire ablation procedure will usually be performed under mild sedation.
Your cardiac pacemaker will first be checked to confirm it is working appropriately. A single intravenous line will be placed in a vein at the top of the right thigh in the groin area through which the ablation catheter will be passed and positioned in the heart using X-ray for guidance. The catheter will then be used to locate the heart’s AV node which sits at the junction of the right atrium and ventricle. Just 60 seconds of radiofrequency energy here is required to ablate the AV node. Your heart rhythm will be observed over a few minutes to confirm the ablation has been successful before the catheter and intravenous line is removed and your pacemaker settings are adjusted. The entire procedure normally takes around 30 min.
Benefits and Risks
AV node ablation is reserved for patients with intrusive AF symptoms who have exhausted all other treatment options.
If you fall in this category, you are likely to experience these benefits.
- Your AF symptoms will improve significantly.
- Your heart will no longer race out of control.
- Your heart will not weaken through overstimulation.
- You will no longer require antiarrhythmic or rate-controlling medications for AF.
This is a common and very low-risk procedure. Aside from occasional pain and bruising around the blood vessel in the right groin area, almost all patients undergoing catheter ablation experience no complications.
The following are extremely rare complications which may occur in 1 in 200 cases.
- Inadvertent dislodgement of a pacemaker lead, requiring repositioning.
- Pacemaker malfunction requiring replacement.
After the procedure, you 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. You may 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 6 to 8 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.
The success rate of the procedure is 98%, with the large majority feeling much better after the procedure. A minority of patients experience residual symptoms even after a successful procedure. Partly, this is because the procedure does not eliminate AF in the top chambers, therefore the heart therefore is not pumping at 100% capacity. However, there are usually additional reasons, including stiffness of the ageing heart muscle and poor overall fitness level due to lack of exercise. A regular exercise program will normally improve residual symptoms over time.