MODULATION OF ATRIOVENTRICULAR-CONDUCTION BY ABLATION OF THE SLOW ATRIOVENTRICULAR NODE PATHWAY IN PATIENTS WITH DRUG-REFRACTORY ATRIAL-FIBRILLATION OR FLUTTER
P. Dellabella et al., MODULATION OF ATRIOVENTRICULAR-CONDUCTION BY ABLATION OF THE SLOW ATRIOVENTRICULAR NODE PATHWAY IN PATIENTS WITH DRUG-REFRACTORY ATRIAL-FIBRILLATION OR FLUTTER, Journal of the American College of Cardiology, 25(1), 1995, pp. 39-46
Objectives. We hypothesized that modulation of atrioventricular (AV) n
ode conduction, allowing a reduction in ventricular rate during atrial
fibrillation or flutter without affecting AV conduction during sinus
rhythm, might be achieved through ablation of the ''slow'' AV node pat
hway. Background. In patients with atrial fibrillation or flutter not
amenable to a direct atrial approach, ablation of the His bundle is pe
rformed to induce complete AV block. This procedure causes pacemaker d
ependence. Methods. Fourteen patients with drug-refractory paroxysmal
atrial flutter or fibrillation underwent ablation of the slow AV node
pathway. Radiofrequency current was delivered in six patients during s
inus rhythm, in six during atrial flutter and in two during atrial fib
rillation. Results. The anterograde effective refractory period of the
AV node was prolonged from 270 +/- 50 (mean +/- SD) to 390 +/- 87 ms
(p = 0.005) and the Wenckebach cycle from 346 +/- 33 to 458 +/- 75 ms
(p = 0.004) in six patients during sinus rhythm. Mean AV ratio increas
ed from 1.6 +/- 0.5 to 3.0 +/- 0.6 (p = 0.02) in six patients with atr
ial flutter. Mean ventricular rate decreased from 157 +/- 38 to 67 +/-
10 beats/min in two patients with atrial fibrillation. Complete AV bl
ock was induced in two patients (transient in one, permanent in one).
During a follow-up period of 5.8 +/- 3.5 months, 11 patients experienc
ed a recurrence of atrial fibrillation at 60 to 95 beats/min. No patie
nt had progression to any degree of AV block . Conclusions. Ablation o
f the slow AV node pathway allows reduction of ventricular rate during
atrial fibrillation or butter while maintaining intact AV conduction
during sinus rhythm. Modulation of AV node conduction is effective in
most patients as an alternative to His bundle ablation for control of
ventricular rate in paroxysmal atrial fibrillation or flutter.