RESUMO
Objective To investigate the mechanisms of right atrial tachycardia(AT) occurring after atriotomy of structural heart disease under the guidance of image integration system(CartoMerge system) and explore the efficacy of catheter ablation by using the aboved technique.Methods From January 2005 to December 2006,forty consecutive drug-refractory patients presenting with AT underwent complete electroanatomic mapping of spontaneously occurring and inducible right ATs.The ablation strategy was to avoid visible anatomic anomaly under the guidance of image integration system and to transect the isthmus,usually targeting the narrowest portion of the isthmus.Patients were followed up on an outpatient basis with clinical evaluation and 24-hour Holter recordings being performed at three months,six months,and afterwards on a yearly basis.Results Three main tachycardia mechanisms were identified: single-loop macroreentrant atrial tachycardia(MAT)(n=36),double-loop MAT(n=16),and focal AT(n=4).In most MATs,critical isthmus areas were identified most frequently the cavotricuspid isthmus(CTI)(n=35) and the surgical incision isthmus(n=36).Surgical incision causing obvious morphological anomalies including scar-like anomaly,pouch-like anomaly,and node-like anomaly could be visible by image integration technique in 12 patients,which had the electrophysiological characteristics of a surgical incision(a CDP or scar).A mean number of 19.5?10.1 radiofrequency(RF) applications were delivered to terminate the circuit.During a follow-up of 18?10 months the RF ablation was acutely successful in all patients.Eight patients(20%) had an early recurrence of MAT and needed an additional ablation procedure.Conclusion Image integration system not only allows reconstruction of AT mechanisms,but also represents an advance in the accurate localization and ablation of the arrhythmogenic substrate of postsurgical AT.Three-dimensional MR/CT images of RA can be successfully extracted and registered to anatomically guide catheter ablation in RA.The display of real and detailed anatomic information during the procedure enables tailored RF ablation to individual distorted anatomy related with surgical incision.