Electrophysiologic study and radiofrequency catheter ablation of isthmus-independent atrial flutter

Isthmus-Independent Atrial Flutter. Introduction: We report the electrophys iologic study and radiofrequency catheter ablation of isthmus-independent a trial flutter in 2 patients. The isthmus-independent atrial flutter in thes e 2 patients had similar ECG and electrophysiologic findings. Both were rep roducibly induced by rapid atrial pacing. The atrial activation sequence an d entrainment study proved that these atrial flutters were not isthmus-depe ndent. A high-right atrial site was identified as the critical site of the slow conduction zone of the tachycardia in both. This site showed double po tentials and mid-diastolic potentials. Radiofrequency catheter ablation at this site successfully eliminated the isthmus-independent atrial flutter in both patients. (J Cardiovasc Electrophysiol, Vol. 10, pp. 728-735, May 199 9).