What is catheter ablation and how does it treat arrhythmias?

Catheter ablation is a procedure that treats an abnormal heart rhythm by finding the small area of heart tissue causing it and disabling that tissue, usually with heat or with extreme cold. Unlike medication, which suppresses a rhythm problem for as long as you keep taking it, ablation sets out to remove the cause.

That distinction is the reason patients ask me about it, and it is the right question to be asking. For some rhythm disorders, ablation is close to a cure. For others it is a very good treatment that may need repeating. Knowing which group you are in is most of the conversation.

How the Procedure Actually Works

Your heart beats because an electrical signal travels through it in an orderly sequence. Heart rhythm disorders happen when that sequence is disrupted, either by an extra electrical pathway that should not exist, or by a patch of tissue firing on its own, or by a signal circling round and round instead of moving on.

Ablation works by finding that spot and putting it out of action.

Fine catheters are passed into the heart through a vein, usually at the top of the leg. Nothing is cut open. Once the catheters are in place, the electrical activity of the heart is mapped in detail, which is an electrophysiological study and is often done in the same sitting. Modern systems build a three dimensional picture of the heart and show exactly where the abnormal signal begins.

The tip of the catheter then delivers energy to that precise area. Radiofrequency energy heats the tissue, or cryoablation freezes it. Either way the result is a small area of scar that no longer conducts electricity, so the abnormal circuit is broken.

Which Arrhythmias It Treats

Ablation is not one operation with one success rate, and honest information here matters more than optimism.

• [Supraventricular tachycardia](https://www.nhs.uk/conditions/supraventricular-tachycardia-svt/). This is the group where ablation performs best. The problem is usually a single extra pathway, and removing it generally resolves the condition permanently. For a young patient having frequent episodes, it is often the treatment of choice rather than a last resort.
• [Wolff Parkinson White syndrome](https://www.nhs.uk/conditions/wolff-parkinson-white-syndrome/). Also caused by an accessory pathway, and also very treatable by ablation. Here there is an additional reason to act, because the pathway itself can occasionally be dangerous rather than merely unpleasant.
• [Atrial flutter](https://www.kingstoncardiologist.com/conditions/atrial-flutter). The circuit is usually predictable and sits in a known part of the right atrium, which makes it a reliable target.
• [Atrial fibrillation](https://www.kingstoncardiologist.com/conditions/atrial-fibrillation). More complex, because the triggers usually sit around the pulmonary veins and the condition is progressive. Ablation works well, particularly for people whose AF comes in episodes rather than being permanent, but a proportion of patients need a second procedure. Understanding how atrial fibrillation behaves makes that much easier to accept in advance.
• Ventricular arrhythmias. A more specialised area, usually managed alongside other treatment.

If you want an overview of where each of these sits, the different rhythm disorders are worth reading first, and the NHS overview of heart rhythm problems covers the same ground in plain terms.

What Happens on the Day

Ablation is usually a day case, though some people stay overnight.

You will be given either sedation or a general anaesthetic depending on the type of ablation and on you. Local anaesthetic numbs the top of the leg, the catheters are placed, and the mapping begins. Part of that process may involve deliberately provoking the arrhythmia so it can be located, which sounds alarming and is entirely controlled.

The procedure itself commonly takes between one and three hours depending on complexity. Afterwards you lie flat for a few hours so the vein at the groin seals properly, and most people are walking about the same evening.

Bruising in the groin is normal. Feeling the occasional extra beat or short run of palpitations in the following weeks is also normal and does not mean the procedure has failed, because the tissue takes time to settle. That is one of the most common worries I am asked about afterwards.

The Risks, Stated Plainly

Ablation is a well established procedure, but it is still an invasive one and it would be dishonest to present it as risk free.

The common issues are minor, mainly bruising and discomfort at the groin. Serious complications are uncommon and include bleeding, damage to the heart or surrounding structures, and, rarely, damage to the heart's normal conduction system requiring a pacemaker. The specific risks differ considerably between a straightforward SVT ablation and a complex AF ablation, so the figures that matter are the ones for your procedure, from the team performing it.

What Recovery Actually Looks Like

Most people are back to normal activity within a few days, and back at work within a week after a straightforward ablation. Driving restrictions vary with the procedure and with your licence type, so ask before you leave rather than assuming.

The part that catches people out is the settling period. For roughly the first six to eight weeks the treated tissue is still healing, and during that time extra beats and short runs of palpitations are common. That does not mean the ablation has failed. Judging the result before that period is over is unfair to the procedure and unnecessarily frightening for the patient, and it is the single most common reason somebody contacts me worried afterwards.

Follow up usually involves a review with a monitor, so the assessment rests on what your rhythm is actually doing rather than only on how you feel. That distinction matters in both directions. Some people continue to notice occasional beats while their underlying rhythm has returned entirely to normal, and a smaller number feel nothing at all while the arrhythmia is still present.

Medication is often continued for a period and then reviewed, rather than stopped on the day of the procedure.

How I Approach the Decision

Palpitations are one of the most common reasons people are referred, and rhythm problems are Dr Jogiya's main specialist interest. Not everyone referred with palpitations turns out to be a candidate for ablation. Many have a rhythm that does not need it, or symptoms that turn out not to be arrhythmic at all.

The first job is always proof. You cannot ablate a rhythm nobody has recorded, and an ECG captured between episodes is frequently normal. Longer monitoring is usually what settles it.

Ablation is often preferred to persisting with a third antiarrhythmic drug in a younger patient with documented, symptomatic SVT, because the drugs are suppressing something that a single procedure can usually remove for good, and a person in their thirties otherwise faces decades of medication with its own side effects. For persistent AF in someone in their seventies with other health problems, the balance often tips the other way, and rate control with anticoagulation is the kinder answer.

Dr Jogiya holds the British Heart Rhythm Society examination in electrophysiology and devices, and sees rhythm patients in his NHS posts at Kingston Hospital and Guy's and St Thomas' as well as in private clinic. People reach a rhythm service at very different stages, some within weeks of a first episode and some after years of them. What matters most is getting the rhythm recorded, because everything after that is a decision rather than a guess.

If you have blackouts alongside palpitations, that combination needs urgent assessment rather than a routine appointment. If you have chest pain with a racing heart, or you collapse, call 999.

Conclusion

Catheter ablation treats the cause of an abnormal heart rhythm rather than masking it, by mapping the heart's electrical activity and disabling the small area responsible. For supraventricular tachycardia and Wolff Parkinson White syndrome it is often close to definitive. For atrial fibrillation it is effective but more complex, and sometimes needs more than one attempt.

Whether it is right for you depends on which arrhythmias you actually have, how much it affects your life, your age and what else is going on. None of that can be settled without a recording of the rhythm itself, which is where any sensible assessment starts.

If you have palpitations that have not been explained, if you have been offered ablation and would like to talk it through, or you would like a second opinion on a rhythm problem, you can contact me, Dr Roy Jogiya, at Kingston Cardiologist to arrange a proper rhythm assessment in Kingston upon Thames or central London. Appointments are available in person and virtually, with full diagnostic support including extended rhythm monitoring.