Any supraventricular tachycardia (SVT) that requires only atrial tissue for its initiation and maintenance can properly be considered an atrial tachyarrhythmia. Although a relatively uncommon form of SVT, atrial tachycardia tends to be refractory to pharmacologic therapy and is therefore frequently treated with ablative therapy.
Current catheter ablative techniques have evolved from open surgical techniques in which the arrhythmia focus was identified using intraoperative mapping and then excised [1,2]. Direct current (DC) shock catheter ablation (fulguration) was used for a short time in small numbers of patients with atrial tachycardia; this technique has been completely supplanted by radiofrequency (RF) catheter ablation.
Radiofrequency catheter ablation (RFCA) techniques and outcomes in patients with atrial tachycardia will be reviewed here. Ablative techniques for the management of atrial fibrillation, and atrial flutter, both typical and atypical flutter, are discussed separately. (See "Radiofrequency catheter ablation to prevent recurrent atrial fibrillation" and "Maintenance of sinus rhythm after cardioversion in atrial flutter".)
ATRIAL TACHYCARDIAS AMENABLE TO CATHETER ABLATION
Atrial tachycardia may be unifocal or multifocal; some unifocal tachycardias originate in or around the sinus node.
- Unifocal (or ectopic) atrial tachycardia may have an automatic or reentrant mechanism, and a paroxysmal or incessant pattern (waveform 1 and waveform 2 and waveform 3). Most varieties of unifocal atrial tachycardia are amenable to catheter ablation. Like atrial fibrillation, focal atrial tachycardia may arise from the pulmonary venous ostia [3,4]. The pathophysiology appears to be related, but not identical, to that of focal AF . (See "Intraatrial reentrant tachycardia" and "Focal atrial tachycardia" and 'Indications for catheter ablation' below and "Radiofrequency catheter ablation to prevent recurrent atrial fibrillation".)
- Sinoatrial node reentrant tachycardia (SNRT) is a specific type of unifocal atrial tachycardia in which sinoatrial (SA) nodal or peri-SA nodal tissue is part of the reentry circuit; this results in P waves during tachycardia which may be indistinguishable from normal sinus P waves [5,6]. (See "Sinoatrial nodal reentrant tachycardia (SANRT)".)
- Inappropriate sinus tachycardia (IST), also known as chronic nonparoxysmal sinus tachycardia, is a distinct syndrome in which the resting sinus rate is elevated and there is an exaggerated chronotropic response to exercise . Although IST is most often treated with beta blockers, ablation may be considered in refractory patients. (See "Sinus tachycardia".)
- Occasionally, patients with more than one discrete ectopic atrial focus are candidates for curative ablation. Multifocal atrial tachycardia (MAT), however, is due to abnormal automaticity or triggered activity throughout the atria, and is therefore not curable with standard catheter techniques (waveform 4). Refractory patients with MAT may benefit from complete atrioventricular junctional ablation and permanent pacemaker implantation or AV nodal modification . (See "Multifocal atrial tachycardia".)