Bidirectional isthmus conduction block has been associated with a low
recurrence rate after atrial Butter ablation, We present the case of a
type I, typical or ''counterclockwise'' atrial flutter ablation guide
d by stimulation and recordings obtained from a basket catheter, which
allowed for constant electrogram recording from splines positioned al
ong the right lateral free wall and septum, After atrial flutter termi
nation with radiofrequency application, the ability to record and stim
ulate from multiple sites in the-atrium using the basket catheter was
useful to detect residual bidirectional slow conduction through the is
thmus, Complete isthmus block could be documented after additional rad
iofrequency energy applications.