title: The superior transseptal surgical approach to mitral valve creates slow conduction.
abstract: BACKGROUND
  Atrial tachycardia is very frequent after mitral valve surgery using the superior transseptal approach.
  
  
  METHODS
  Sixteen patients operated on for mitral valve disease (superior transseptal approach = Group A, n = 9, and left atrial approach = Group B, n = 7) underwent radiofrequency catheter ablation of atrial tachycardia guided by electroanatomic mapping. Twenty-six consecutive patients without previous cardiac surgery with typical atrial flutter served as controls (Group C).
  
  
  RESULTS
  Atrial tachycardia occurred earlier after the operation in Group A than in Group B (median 97 vs 2,159 days, P = 0.003). Typical atrial flutter was the most frequent circuit in all groups (Group A-7 patients, Group B-5 patients, Group C-26 patients). Three patients in Group A developed right atrial incisional tachycardia. Ten of 14 tachycardia circuits (typical atrial flutter, n = 7, incisional tachycardia, n = 3) in Group A depended on the corridor between the right atrial part of the atriotomy and the tricuspid annulus. Slow conduction during typical atrial flutter was detected in this corridor in Group A, but not in the corresponding region in Groups B and C (P < 0.001). The cycle length of typical atrial flutter was longer in Groups A and B than in Group C (mean 283 ms and 282 ms vs 233 ms, P = 0.003). Patients in Group B with typical atrial flutter had larger right atria than patients in Group A or Group C (mean 156 mL vs 96 mL and 113 mL, P = 0.033).
  
  
  CONCLUSIONS
  The superior transseptal incision may predispose to atrial tachycardia by creating slow conduction between the atriotomy and the tricuspid annulus.
authors.affiliation: Department of Cardiology, Aarhus University Hospital at Skejby, Aarhus, Denmark. lukacpe2@hotmail.com
authors.forename: Peter
authors.initials: P
authors.lastname: Lukac
authors.forename: Vibeke
authors.initials: V
authors.lastname: Hjortdal
authors.forename: Anders K
authors.initials: AK
authors.lastname: Pedersen
authors.forename: Henrik K
authors.initials: HK
authors.lastname: Jensen
authors.forename: Peter T
authors.initials: PT
authors.lastname: Mortensen
authors.forename: Peter S
authors.initials: PS
authors.lastname: Hansen
mesh_terms: D000328:Adult; D000368:Aged; D000704:Analysis of Variance; D001281:Atrial Fibrillation / Q000209:etiology / Q000503:physiopathology / Q000601:surgery*; D001282:Atrial Flutter / Q000209:etiology / Q000503:physiopathology / Q000601:surgery*; D017115:Catheter Ablation; D022062:Electrophysiologic Techniques, Cardiac; D005260:Female; D006329:Heart Conduction System / Q000503:physiopathology; D006346:Heart Septum / Q000601:surgery; D006801:Humans; D008297:Male; D008875:Middle Aged; D008944:Mitral Valve Insufficiency / Q000601:surgery; D012189:Retrospective Studies; D018709:Statistics, Nonparametric; D016896:Treatment Outcome