Catheter Ablation
Catheter ablation (CA) is carried out in the specialised Cardiac Angiography Suite. Ablation simply means destroying tissue, and in this case it is destroying abnormal tissue in the heart that is causing heart rhythm problems. Like an electrophysiology study the procedure involves a number of small, flexible tubes (or catheters) being inserted into veins (and occasionally into the artery) in the groins, and then guided up into the heart under x-ray control. Once the abnormality has been identified, the ablation catheter itself is inserted and directed towards the pathway(s) of the abnormal electrical currents. These pathways are ‘ablated’ using small, precise, controlled burns (or sometimes freezing). Some patients feel a slight discomfort during the ablation, despite the sedation, and so more pain relief will be given. The procedure can take between 2-5 hours, depending on the type of rhythm being ablated.
Success rates using CA are:
- 95-97% of patients with SVT are completely cured although 10-15% may require a further procedure at some point in the future if symptoms return.
- 90% of patients with atrial flutter are completely cured although they may require more than one session of CA, and may they have co-existing rhythm disturbances which may need other forms of treatment.
Risks include:
- Bruising at the groin where the catheter is inserted, and in 1% of patients this may require surgery to close the hole where the catheter was inserted. The DVLA stipulate a 2-day driving ban following ablation although we recommend that you do not drive for a week after the procedure, due to the bruising in the groin;
- Disruption of the normal electrical circuits of the heart requiring insertion of a pacemaker (0.5%-1.0%); and
- Very rarely, death (0.05-0.1%).
Catheter ablation of AF is quite different to ablation of the other SVT arrhythmias and atrial flutter. The aim of the procedure is to ablate ‘noise generators’ in the atria that may trigger and/or maintain AF. Many of these are in the left atrium and particularly in or around the pulmonary veins. This procedure can be done either under heavy sedation or general anaesthetic, but many of people do choose a general anaesthetic because it is often a slightly longer procedure and can be quite painful. A transoesophageal echocardiogram is performed to ensure there are no clots within the left atrium before starting. The procedure is then performed with a view to discharging the patient the following day. Prior to the procedure itself a cardiac MRI scan is done to give detailed information on the anatomy of the left atrium. Whilst performing the ablation the catheters are carefully manipulated from the groin into the heart and across from one side to the other and then quite extensive ablation of the tissue performed with a view to hopefully completely removing the AF tendency. In patients with paroxysmal AF there is approximately an 80-85% chance that they maintain normal rhythm predominantly, without any medication, with persistent AF it is about 75-80%.However approximately 30-40% of people will need the procedure done twice or more to achieve this result. It is however impossible to predictexactly who these patients will be. Warfarin is normally given for at 3 months afterwards, and the risks of serious complications such as death or heart attack are less than 1/1000. The risk of vascular damage or needing a pacemaker is also low and although there is a small risk of perforation related to the procedure this can normally be dealt with straightforwardly in the few cases where it occurs. The main concern for most people either performing or undergoing these procedures is the risk of stroke which is probably less than 1% nowadays and every precaution to minimise this.