Atrial flutter ablation using a technique for detection of conduction block within the posterior isthmus

Catheter ablation orientated on the induction of a functional intraatrial b lock within the posterior isthmus of the tricuspid annulus has been shown t o effectively abolish atrial flutter. In order to improve and simplify the current technique, a strategy based on an electrode catheter for combined r ight atrial and coronary sinus mapping and stimulation was explored prospec tively. Twenty-four consecutive patients referred for catheter ablation of recurrent type I atrial putter were included. A steerable 7 Fr catheter (Me dtronic/Cardiorhythm) composed of two segments with 20 electrodes was used for right atrial and coronary sinus activation mapping and stimulation. Mul tiple steering mechanisms allowing intubation and positioning of the distal part within the coronary sinus were incorporated into the device. Adequate positioning of the mapping catheter was achieved solely via a transfemoral approach in all patients after 7.7 +/- 4.6 minutes, providing stable elect rogram recordings during the entire ablation procedure. Radiofrequency curr ent ablation (16.3 +/- 9.6 pulses) caused a significant bidirectional incre ase of the mean intraatrial conduction times via the posterior isthmus irre spective to the stimulation interval. Significant changes of intraatrial co nduction properties were induced during ablation in 22 of 24 patients (bidi rectional block: n = 18, unidirectional block: n = 3, conduction delay: n = 1, unchanged conduction: n = 2). Following ablation atrial flutter was non inducible in all patients. Twenty-two of 24 patients (92%) remained free of atrial flutter episodes during a follow-up of 12.5 +/- 5.7 months. Two of six patients without a bidirectional conduction block had a recurrence of a trial flutter. Atrial flutter ablation guided by the induction of an intraa trial conduction block can be effectively performed with this novel strateg y for combined mapping of the posterior tricuspid isthmus, including corona ry sinus and right atrial free wall. This transfemoral approach has a high accuracy with respect to the defection of radiofrequency current-induced ch anges of intraatrial conduction patterns.