title: Radiofrequency ablation of left atrial flutter mediated with double potentials in a seemingly normally structured heart.
abstract: BACKGROUND
  Left atrial flutter (left AFL) is common in patients who undergo atrial fibrillation ablation and cardiac surgery; however, few reports describe left AFL in detail in a seemingly normally structured heart, and the mechanisms of the occurrence of such arrhythmia are still not clear. We describe left AFL in patients without prior cardiac surgery or catheter ablation and discuss the electrophysiological characteristics that may explain the preferential generation and perpetuation of such tachycardia.
  
  
  RESULTS
  Eleven patients with left AFL, who had no history of cardiac surgery or interventions, underwent electrophysiological studies and 3-dimensional electroanatomic mapping studies. Echocardiography revealed a relatively mild dilation of the left atrium, mild to moderate mitral regurgitation, and a normal left ventricular ejection fraction. The electroanatomic mapping during tachycardia showed a "reentrant" activation pattern in all patients. The mean tachycardia cycle length was 266 ± 17 ms. A single-loop reentrant circuit was identified in 7 patients. A counterclockwise left atrial flutter evolved around the mitral valve annulus in 6 patients. The tachycardia rotated around the left atrial anterior wall in 1 patient. Four patients exhibited a double-loop reentrant circuit with a "figure of 8" pattern reentry. Double potentials as the critical isthmus of the circuit were identified in the left atrial anterior wall near the mitral annulus which displayed a low-voltage area matched with the left atrium-aorta contiguity. The conduction velocity was significantly slower in the double-potential recording area than in the lateral mitral annulus (0.36 ± 0.03 m/s vs 0.74 ± 0.12 m/s; P<0.05). Successful ablation around the double-potential recording site caused an interruption of the tachycardia, and remained free of recurrence during a 12-month follow-up in all patients.
  
  
  CONCLUSIONS
  Left AFL in patients without a history of surgery or ablation is rarely observed in clinical practice. The successful site of ablation was within the anterior wall near the mitral annulus showing the double potentials as the critical part of the reentrant circuit. This suggests that perhaps a double potential-targeted ablation may be effective for these patients.
authors.affiliation: Section of Electrophysiology, Division of Cardiology, Beijing Friendship Hospital Affiliated to Capital Medical University, Beijing, China.
authors.forename: Hui
authors.initials: H
authors.lastname: Peng
authors.affiliation: Section of Electrophysiology, Division of Cardiology, Beijing Friendship Hospital Affiliated to Capital Medical University, Beijing, China.
authors.forename: Zhijun
authors.initials: Z
authors.lastname: Sun
authors.affiliation: Section of Electrophysiology, Division of Cardiology, Beijing Friendship Hospital Affiliated to Capital Medical University, Beijing, China.
authors.forename: Heping
authors.initials: H
authors.lastname: Zhang
authors.affiliation: Section of Electrophysiology, Division of Cardiology, Beijing Friendship Hospital Affiliated to Capital Medical University, Beijing, China. Electronic address: liumanyi0921@hotmail.com.
authors.forename: Yongquan
authors.initials: Y
authors.lastname: Wu
mesh_terms: D000368:Aged; D001282:Atrial Flutter / Q000000981:diagnostic imaging* / Q000503:physiopathology / Q000601:surgery; D018780:Body Surface Potential Mapping / Q000379:methods; D017115:Catheter Ablation / Q000379:methods; D019560:Echocardiography, Three-Dimensional / Q000379:methods; D005260:Female; D005500:Follow-Up Studies; D006325:Heart Atria / Q000000981:diagnostic imaging* / Q000601:surgery; D006801:Humans; D008297:Male; D008875:Middle Aged
keywords: Atrial flutter; Catheter ablation; Double potential; Electrophysiology; Mapping