Curing reentrant atrial arrhythmias: Targeting protected zones of slow conduction by catheter ablation

Radiofrequency catheter ablation has become the treatment of choice for paroxysmal supraventricular tachycardia involving dual atrioventricular nodes or an accessory pathway. For reentry confined to the atrium where the arrhythmia itself or the ventricular response cannot be controlled with drugs, catheter ablation of the His bundle is a treatment option, but requires implantation of a permanent pacemaker and does not restore normal rhythm. In the atria, important anatomic obstacles, such as the great veins and the ostium of the coronary sinus, interrupt the normal arrangement of myocardial fibers. Under certain circumstances these natural obstacles, or those created during atrial surgery for congenital heart disease, may help to facilitate conditions for reentrant excitation within the atrium. The purpose of this study was to evaluate the safety and efficacy of radiofrequency ablation directed at a protected isthmus of slow conduction in patients with reentrant atrial tachycardia or flutter. Eighteen patients with drug refractory atrial arrhythmias underwent invasive electrophysiology testing, followed in the same session by ablation using radiofrequency energy delivered between the large distal electrode of a deflectable catheter and a skin patch. In eight patients, intracardiac echocardiographic imaging was performed to compliment fluoroscopy. These 18 patients had a total of 20 atrial tachyarrhythmias atypical atrial flutter (1 patient), typical atrial flutter (13), intraatrial reentrant tachycardia (5), and sinus node reentry (1). There were 5 women and 13 men with an age range of 8 to 81 years. Structural heart disease was present in 10 of 14 patients with atrial flutter, and 4 patients with intraatrial reentrant tachycardias had surgery for congenital heart disease. Acute success was achieved in 12 of 13 cases (92%) of typical atrial flutter and in 6 of 6 cases of other atrial reentrant tachyarrhythmias, including sinus node reentry and five arrhythmias associated with congenital heart disease surgery. One patient developed a deep venous thrombosis. Radiofrequency catheter ablation, by severing narrow corridors of slow conduction, can safely abolish reentrant atrial arrhythmias in humans. Long-term follow-up evaluation will be required since these patients generally have atrial disease and recurrence of the ablated arrhythmia or the emergence of new arrhythmias is a possibility.