Ablation therapy for arrhythmias

Cardiac arrhythmias most commonly result from the development of a re-entry circuit caused by a developmental anomaly (e.g. Wolff-Parkinson White Syndrome where the re-entrant pathway is due to the presence of a congenital accesory pathway) or a myocardial scar. The destruction of this and any other abnormal electrical circuits is termed 'ablation therapy'. Radiofrequency ablation came into clinical practice at the end of the 1980's and revolutionise the way patients with abnormal heart rhythms could be treated and sometimes cured.

• radiofrequency ablation:
  • cardiac catheter introduced to the cardiac chambers via the peripheral vascular system
  • an electrode is mounted on the end of the cardiac catheter through which a radiofrequency is passed - the passage of current results in a very localised lesion (4-5mm in depth and diameter) that is adequate to eradicate electrical pathways but has no effect (either short or long term) on cardiac function
  • rarely complications can occur if the lesion is situated in a critical area e.g. ablation of a pathway close to the AV node may require implantation of a pacemaker (<1% of cases); also cardiac wall perforation is a rare complication
    
    
• arrhythmias suitable for ablation:
  • in general, supraventricular tachycardias tend to be easier and less dangerous to ablate curatively than ventricular tachycardia, since with the exception of atrial flutter and atrial fibrillation, most cases are the consequence of developmental electrical abnormal connections
  • in patients who are very debilitated by atrial fibrillation a decision may be taken to interrupt the atrioventricular node and then control the rhythm of the ventricles with an implanted pacemaker
  • ablation therapy combined with antiarrhythmic drug therapy is superior to antiarrhythmic drug therapy alone in preventing atrial arrhythmia recurrences in patients with paroxysmal or persistent AF in whom antiarrhythmic drug therapy has already failed (1)

Reference:

1. Stabile G et al. Catheter ablation treatment in patients with drug-refractory atrial fibrillation: a prospective, multi-centre, randomized, controlled study (Catheter Ablation For The Cure Of Atrial Fibrillation Study). Eur Heart J 2006;27:216-21.
2. British Heart Foundation, Factfile 1/2001.