[Supraventricular tachycardias: mechanism, diagnosis and therapy]

Most of the paroxysmal forms of supraventricular tachycardia are reentry tachycardias in origin with either an AV-nodal reentry (AVNRT; approx. 50%) or an AV reentry circuit via accessory pathway (AVRT; approx. 30%) as the anatomical basis of tachycardia. The therapeutic options include either drug therapy or transcatheter radiofrequency ablation. In asymptomatic patients, where supra-ventricular tachycardia or WPW syndrome was documented incidentally, an expectative approach without therapy is usually recommended. However, if frequent tachycardia recurrences or severe clinical symptoms (syncope, pre-syncope make treatment mandatory, medical therapy with either betablockers, calcium antagonists or digoxin should be tried if AV-nodal reentry tachycardia is the mechanism (no evidence of WPW syndrome on the 12-lead ECG). In patients with symptomatic WPW syndrome or drug refractory AV-nodal reentry tachycardia, transcatheter radiofrequency ablation with its good results and low complication rate is the therapy of choice. The treatment modality is particularly indicated in young patients who otherwise would need lifelong drug therapy. In contrast, supraventricular tachycardias with badly defined anatomical substrate, such as multifocal atrial tachycardias or atrial fibrillation, should in the first place be treated medically and not by radiofrequency ablation.