Clinical characteristics and electrophysiological features in patients with focal atrial tachycardia originating from the nonseptal region of tricuspid annulus

Objective To observe the clinical characteristics and electrophysiological features in patients with focal atrial tachycardia (AT)originating from the nonseptal region of tricuspid annulus (TA). Methods From August 2005 to October 2014, the patients underwent successful radiofrequency catheter ablation (RFCA) for focal AT were enrolled in the study, and the clinical and electrophysiological data of patients with a TA focus were reviewed. Result Among the 318 patients with focal AT, 16 (5.03%)patients had focal AT originating from nonseptal region of TA. Most of the TA focus (9/16 cases)were localized in the segment of the TA between 6: 00 and 8: 00. Along with the TA focus clockwise from 6: 00 to 12: 00, the P wave morphology during AT changed from positive to negative in leads aVL and aVR, from negative to positive in inferior leads, and from negative to positive in leads V5~6. The P wave morphology may be determined by the right atrial conduction and preferential interatrial conduction. Conclusion The nonseptal region of TA is an uncommon origin of focal AT, and most of the TA focus were localized in the segment of the TA between 6: 00 and 8: 00. The TA focus from different segments have characterized P wave morphologies.