Treatments - Catheter Ablation

The use of minimal access ‘key-hole’ surgery to cure many disturbances of rhythm has been available for over 15 years. The common tachycardias, particularly supraventricular tachycardias and atrial flutter, are particularly amenable to this treatment. It may also be useful in selected patients with ventricular tachycardia, particularly those patients who have no evidence of any other heart disease. More recently there has been intense research into techniques to cure atrial fibrillation, and the success rates are rapidly improving. See diagnosis section, arrhythmias.

In general ablation procedures are carried out under local anaesthetic, with appropriate sedation, through veins in one or both groins. Fine wires are advanced through the veins into the heart and record electrical activity. If the abnormal heart rhythm is present at the time of the study the electrical recordings allow an accurate diagnosis to be made. If a normal rhythm is present, pacing the heart through the wires almost always allows the abnormal rhythm to be triggered off and diagnosis of the arrhythmia. This is the diagnostic part of the procedure and is vital before any treatment can be given.

Once a diagnosis is made, another wire can be introduced that delivers (usually radiofrequency) energy to the source of the arrhythmia. This is usually relatively painless, although sometimes warmth in the chest is felt. If the procedure is painful, strong morphine like painkillers are given. One or more lesions of radiofrequency energy may need to be delivered to eliminate the abnormal electrical pathway or focus and cure the arrhythmia.

For supraventricular arrhythmias and atrial flutter, success rates of 90% or more are usually achieved. The success rates are probably lower for patients with ‘normal heart’ ventricular tachycardia. The success rates for atrial fibrillation are very difficult to access because the treatment is fairly new, and long term follow up data are not available. For so-called paroxysmal AF (that is stop-start AF), success rates of up to 80-90% are published.

In addition to the small risk of damaging a leg vein, there are additional risks of an ablation. These partly depend on the type of arrhythmia being ablated and will be discussed with you in detail if you are considering the treatment. It is possible to damage the normal electrical wiring of the heart leaving the heart beating to slowly, and the need for a permanent pacemaker. This risk is rarely above 1%. A significant minority of arrhythmias arise on the left hand side of the heart (including atrial fibrillation). Ablating left sided arrhythmias carries a very small risk of blood clots and stroke. This risk is approximately 1 in 1000 for routine supraventricular tachycardias, but may be slightly higher for AF. An additional small risk is that of a blood lead around the heart that has to be drained away through the skin under the breast bone. This occurs in perhaps 1 in every 200-300 cases, again slightly more frequent for AF ablation.

The commonest complication is probably failure or recurrence (a damaged area of ablation recovering). This is seen in 5-10% of cases, and often a second procedure is offered and is successful in eliminating the problem.