[Catheter ablation of atrial flutter. Electrophysiological characterization of posterior and septal isthmus block].
OBJECTIVE
Evaluate the different types of conduction blocks obtained between inferior vena cava-tricuspid annulus (posterior isthmus) and between tricuspid annulus-coronary sinus ostium (septal isthmus) after radiofrequency (RF) catheter ablation of atrial flutter (AFL).


METHODS
In 16 procedures, 14 patients (pts), 9 male, with type I AFL underwent RF ablation. Atrial activation around tricuspid annulus was performed with a 10-bipole "Halo" catheter (H1-2; H19-20). In sinus rhythm, isthmus conduction was evaluated during proximal coronary sinus (PCS) and low lateral right atrium (H1-2) pacing, before and after linear ablation. According to the wave front of impulse propagation we assessed absence of block (bidirectional conduction); incomplete block (bidirectional conduction with delay in one front of impulse propagation) and complete block (absence of conduction). The PCS/H1-2 interval was measured before and after ablation.


RESULTS
Complete isthmus block was achieved in 7 (44%) and incomplete block in 4 (25%) procedures. Conduction block was not achieved in 5 procedures. At a mean follow-up of 12 months, there were no recurrences in the pts with complete block, whereas AFL recurred in the 6 pts with incomplete or no conduction block (p < 0.001). Pts with complete block had delta PCS/H1-2 interval (74.0 +/- 26.0 ms) greater than incomplete (30.5 +/- 7.5 ms) or absent block (p < 0.05).


CONCLUSIONS
The verification of complete isthmus conduction block with atrial multipolar mapping is an effective strategy to assess electrophysiological success and absence of late recurrence in common atrial flutter ablation.
Moreira
J M
JM
Escola Paulista de Medicina-UNIFESP.
Alessi
S R
SR
Rezende
A G
AG
Prudêncio
L A
LA
de Paola
A A
AA
D000293:Adolescent; D000328:Adult; D000368:Aged; D001282:Atrial Flutter / Q000503:physiopathology / Q000601:surgery*; D002304:Cardiac Pacing, Artificial; D017115:Catheter Ablation; D004594:Electrophysiology; D005260:Female; D005500:Follow-Up Studies; D006346:Heart Septum / Q000601:surgery*; D006801:Humans; D008297:Male; D008875:Middle Aged; D014261:Tricuspid Valve / Q000503:physiopathology; D014682:Vena Cava, Inferior / Q000503:physiopathology
Ablação por cateter do flutter atrial. Caracterização eletrofisiológica da interrupção da condução pelos istmos posterior e septal.