Radiofrequency Catheter Ablation For Patients With Atrial Tachycardia

OBJECTIVE:To study electrophysiologic mechanisms and the original site of atrial tachycardia (AT),to evaluate the efficacy and safety of radiofrequency catheter ablation (RFCA) for AT,to investigate the factors related to failure of this treatment and to recurrence of AT after the initial success. METHOD:Electrophsiologic study and RFCA were performed in consecutive 58 patients with AT who were devided into two groups of automatic and nonautomatic tachycardia. Mapping techniques were based on identification of the earliest endocardial atrial electrogram recorded during AT with one large-tipped catheter or with Halo catheter of twenty polars,then performed ablation at the site of origin of AT. The items analyzed were the location of AT,the efficacy and safety of RFCA and the cause of recurrence after ablation. RESULTS:In 58 patients,electrophysiologic study showed that the mechanism of AT was automatic (12 patients) and nonautomatic (46 patients). AT ablation was successful in 53 patients (51 patients of right-sided AT,2 patients of left -sided AT). 5 patients recurred during follow-up of 2 to 12 months,and repeat ablation was successful in 4 patients. The foci in 53 successfully ablated patients were separately located in right free wall (26 patients),coronary sinus ostia (12 patients),interatrial septum (9 patients) ,right atrial appendage (3 patients),left and right upper pulmonary venous ostia (2 patients) and middle cardiac vein (1 patient) . There were no serious complications such as inadvertent complete heart block and heart tamponade. CONCLUSION:RFCA of AT could be performed safely and successfully. The foci were mainly located in right free wall,coronary sinus ostium and interatrial septum. The mean local endocardial electrogram time (relative to surface P-wave onset) was 47+12 ms at successful ablation sites and 26+8ms at unsuccessful sites (P<0. 05). ATlocated in the left atrium or some other special sites such as the area close to atrial scar,and the target mapped unsatisfiedly were associated with noneffective ablation. It is passible that some cases ofsupreventricular tachycardia have been wrongly classified as AT.