title: Characterization of the anatomy and conduction velocities of the human right atrial flutter circuit determined by noncontact mapping.
abstract: OBJECTIVE
  This study was done to characterize human right atrial (RA) flutter (AFL) using noncontact mapping.
  
  
  BACKGROUND
  Atrial flutter has been mapped using sequential techniques, but complex anatomy makes simultaneous global RA mapping difficult.
  
  
  METHODS
  Noncontact mapping was used to map the RA of 13 patients with AFL (5 with previous attempts), 11 with counterclockwise and 2 with clockwise AFL. "Reconstructed" electrograms were validated against contact electrograms using cross-correlation. The Cartesian coordinates of points on a virtual endocardium were used to calculate the length and thus the conduction velocity (CV) of the AFL wave front within the tricuspid annulus-inferior vena cave isthmus (IS) and either side of the crista terminalis (CT).
  
  
  RESULTS
  When clearly seen, the AFL wave front split (n = 3) or turned in the region of the coronary sinus os (n = 6). Activation progressed toward the tricuspid annulus (TA) from the surrounding RA in 10 patients, suggesting that the leading edge of the reentry wave front is not always at the TA. The IS length and CV was 47.73 +/- 24.40 mm (mean +/- SD) and 0.74 +/- 0.36 m/s. The CV was similar for the smooth and trabeculated RA (1.16 +/- 0.48 m/s and 1.22 +/- 0.65 m/s, respectively [p = 0.67]) and faster than the IS (p = 0.03 and p = 0.05 for smooth and trabeculated, respectively).
  
  
  CONCLUSIONS
  Noncontact mapping of AFL has been validated and has demonstrated that IS CV is significantly slower than either side of the CT.
authors.affiliation: St. Mary's Hospital and Imperial College School of Medicine, London, United Kingdom. r.schilling@ic.ac.uk
authors.forename: R J
authors.initials: RJ
authors.lastname: Schilling
authors.forename: N S
authors.initials: NS
authors.lastname: Peters
authors.forename: J
authors.initials: J
authors.lastname: Goldberger
authors.forename: A H
authors.initials: AH
authors.lastname: Kadish
authors.forename: D W
authors.initials: DW
authors.lastname: Davies
mesh_terms: D000328:Adult; D000368:Aged; D001282:Atrial Flutter / Q000000981:diagnostic imaging / Q000473:pathology* / Q000503:physiopathology*; D004553:Electric Conductivity; D004562:Electrocardiography; D022062:Electrophysiologic Techniques, Cardiac / Q000379:methods*; D005260:Female; D006325:Heart Atria / Q000000981:diagnostic imaging / Q000473:pathology / Q000503:physiopathology; D006801:Humans; D008297:Male; D008875:Middle Aged; D011859:Radiography; D015203:Reproducibility of Results; D014261:Tricuspid Valve / Q000503:physiopathology; D014682:Vena Cava, Inferior / Q000503:physiopathology