Radiofrequency Catheter Ablation of Sustained Intra-atrial Reentrant Tachycardia in Adult Patients Identification of Electrophysiological Characteristics and Endocardial Mapping Techniques

Background. Information about electrophysiological characteristics and radiofrequency ablation of intra-atrial reentrant tachycardia has not been reported before. We proposed that induction and termination of intra-atrial reentrant tachycardia by atrial extrastimuli or rapid atrial pacing and resetting the response pattern by atrial extrastimuli during intra-atrial reentrant tachycardia could ensure the mechanism of reentry and that the earliest site of endocardial activation and concealed entrainment pace mapping with the shortest stimulus-P wave interval could localize a critical area responsible for intra-atrial reentrant tachycardia and radiofrequency ablation. Methods and Results. Seven patients with refractory atrial tachycardia were referred for electrophysio-logical studies and radiofrequency ablation. Electrophysiological studies and endocardial mapping found (1) 10 atrial foci with atrial tachycardia cycle length of 406±41 ms; (2) atrial tachycardia had induction and termination by atrial extrastimuli (8 of 10) or rapid atrial pacing (10 of 10); (3) atrial tachycardia had increasing (6 of 10) or mixed (flat and increasing, 4 of 10) resetting response pattern, with resetting interval of57±13 ms (14±4 % of atrial tachycardia cycle length); (4) exit sites of atrial tachycardia in right atrial free wall (6 of 10), right atrial septum (3 of 10), and midposterior left atrium (1 of 10); and (5) earliest activation site had timing relative to P wave by-37±7 ms, and concealed entrainment pace mapping had shortest stimulus-P interval 23±3 ms. By the endocardial activation pace-mapping technique, radiofrequency energy (8±1 pulses, 31±3 W, 101±11 seconds) successfully eliminated the 10 atrial foci without recurrence (follow-up, 16+5 months). Conclusions. Mechanism of intra-atrial reentrant tachycardia could be confirmed by the electrophysi-ological characteristics, and radiofrequency ablation energy delivered to a critical area in the atrial reentrant circuit is safe and effective for the treatment of intra-atrial reentrant tachycardia. (Circulatio