Key result
Adenosine required mean doses of 1.4 mg, 4.2 mg, and 8.5 mg to produce conduction block at the antegrade fast, antegrade slow, and retrograde fast pathways, respectively, in AVNRT patients (p<0.01).
Why the study?
Does adenosine have differential depressant effects on the antegrade fast, antegrade slow, and retrograde fast pathways in patients with AVNRT?
Does adenosine have differential depressant effects on the antegrade fast, antegrade slow, and retrograde fast pathways in patients with AVNRT?
Adenosine exhibits a differential potency in depressing AV nodal conduction pathways, being most potent on the antegrade fast pathway, followed by the antegrade slow pathway, and least potent on the retrograde fast pathway.
Answers are grounded in this paper and cite their sources.
Adenosine shows pathway-specific effects in AVNRT; leaves open whether titration informs ablation strategies.
Adenosine has a potent negative dromotropic effect. However, comparative effects of adenosine on the three pathways of atrioventricular (AV) nodal reentry remain unclear. In this study, we sought to determine the effects of adenosine on the antegrade fast, antegrade slow, and retrograde fast pathway conduction in patients with AV nodal reentrant tachycardia (AVNRT). Twenty patients with common slow-fast AVNRT (mean cycle length 360 +/- 49 ms) were studied. The effects of adenosine on the antegrade slow pathway and on the retrograde fast pathway conduction were determined during sustained AVNRT and constant right ventricular pacing at identical cycle lengths (mean 360 +/- 49 ms), respectively. Incremental doses of adenosine were rapidly administered: initial dose of 0.5 mg, followed by stepwise increases of 0.5 or 1.0 mg given at 5-min intervals until termination of AVNRT or second-degree ventriculoatrial block occurred. After the antegrade slow pathway conduction was selectively and completely ablated by radiofrequency catheter ablation, the effect of adenosine on the antegrade fast pathway conduction was evaluated. The dose-response curve of adenosine and the dose of adenosine required to produce AV or ventriculoatrial block among the representative three conduction pathways were compared. The dose-response curve for the effect of adenosine on the antegrade fast pathway lies to the left and upward to that of the effect of adenosine on the antegrade slow pathway which in turn lies to the left and upward to that of the retrograde fast pathway. The mean dose of adenosine required to produce conduction block at antegrade fast, antegrade slow, and retrograde fast pathways were 1.4 +/- 0.5, 4.2 +/- 1.6, and 8.5 +/- 2.6 mg, respectively (p < 0.01). Adenosine has a differential potency to depress antegrade fast, antegrade slow, and retrograde fast pathway conduction in patients with AVNRT. The depressant effect of adenosine on the antegrade fast pathway is more potent than that on the antegrade slow pathway which in turn is more potent than that on the retrograde fast pathway conduction.
No takes yet. Share an insight, caveat, or question.
Lai et al. (2002) studied AV nodal reentrant tachycardia (AVNRT) (n=20). Adenosine vs. Comparison among antegrade fast, antegrade slow, and retrograde fast pathways was evaluated on Mean dose of adenosine required to produce conduction block (p=<0.01). Adenosine required mean doses of 1.4 mg, 4.2 mg, and 8.5 mg to produce conduction block at the antegrade fast, antegrade slow, and retrograde fast pathways, respectively, in AVNRT patients (p<0.01).
Synapse has enriched 5 closely related papers on similar clinical questions. Consider them for comparative context: