Objectives: 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.