[Type I atrial flutter radiofrequency ablation. Importance of bidirectional block of isthmus between the inferior vena cava and of tricuspid valve ring].
OBJECTIVE
To determine the clinical importance of a bi-directional line of block demonstration in the inferior vena cava-tricuspid annulus isthmus as an end-point for radiofrequency (RF) atrial flutter (FL) ablation.


METHODS
Forty consecutive patients (51 +/- 11 years) with type I FL were divided in 2 groups: GI (30 patients) anatomic, non-electrophysiologic isthmus ablation technique (interruption and non-induction FL criteria); and GII (10 patients) anatomic with electrophysiologic evaluation of bi-directional isthmus conduction. The isthmus activation was analyzed before and after anatomic RF ablation with a cateter exploring each side of the line of block, depending on the conduction evaluation (anterograde or retrograde).


RESULTS
FL was interrupted and not reinduced in 26/ 30 (86.6%) GI patients and in 10 (100%) GII patients (p = 0.5558). During follow-up FL recurred in 30% of the patients in both groups. In GII, 6 patients with bi-directional block remained assymptomatic, whereas 3 patients with unidirectional block presented recurrence (p = 0.012).


CONCLUSIONS
Electrophysiologic demonstration of bidirectional line of block in the isthmus is related to long-term success and should be the criterion for interruption of type I atrial FL RF ablation.
Scanavacca
M
M
Instituto do Coração do Hospital das Clínicas, FMUSP.
Sosa
E
E
Velarde
J L
JL
D'Avila
A
A
Hachul
D
D
Reolão
B
B
Sanches
O
O
Silva
M
M
Darrieux
F
F
D001282:Atrial Flutter / Q000503:physiopathology / Q000601:surgery*; D017115:Catheter Ablation / Q000295:instrumentation / Q000379:methods*; D004566:Electrodes; D004594:Electrophysiology; D005260:Female; D005500:Follow-Up Studies; D006329:Heart Conduction System / Q000601:surgery*; D006801:Humans; D008297:Male; D008875:Middle Aged; D014261:Tricuspid Valve / Q000601:surgery*; D014682:Vena Cava, Inferior / Q000601:surgery*