Variable responsiveness of anterograde and retrograde fast pathway conduction to adenosine in patients with typical AV-nodal reentry tachycardia.
Adenosine is known as a substance which depresses predominantly the slow pathway of the av-node. However, the effect of adenosine on the anterograde and retrograde fast pathway (FP) has not been studied in a large patient population. Ninety-one patients with inducible typical av-nodal reentrant tachycardias (AVNRT) were included. The clinically used dosage of 12 mg adenosine was administered subsequently as bolus injection during a constant atrial and ventricular pacing (500 ms) in all patients. Electrophysiological av-nodal parameters were determined. A higher responsiveness of the anterograde compared to the retrograde FP was observed: the majority of patients (76%) blocked anterogradely and 55% blocked retrogradely within the FP after the administration of 12 mg adenosine. Thirty-six percent of all patients revealed a differential behaviour to adenosine. Sixteen percent of all patients were completely resistant to adenosine (P=0.012). Electrophysiological parameters did not predict the responsiveness of the FP to adenosine. In patients with typical AVNRT the anterograde FP shows a higher sensitivity than the retrograde FP to adenosine. This might reflect an anatomical and/or functional distinction between anterograde and retrograde FP. The variable response to adenosine could be due to individual anatomical and electrophysiological heterogenity of the perinodal tissue and the av-node.
Mewis
C
C
Department of Cardiology, University Hospital Tübingen, Tübingen, Germany. christian.mewis@med.uni-tuebingen.de
Kühlkamp
V
V
Bosch
R F
RF
Seipel
L
L
D000241:Adenosine; D000328:Adult; D000889:Anti-Arrhythmia Agents; D016009:Chi-Square Distribution; D004305:Dose-Response Relationship, Drug; D005260:Female; D006329:Heart Conduction System / Q000187:drug effects* / Q000503:physiopathology; D006801:Humans; D008297:Male; D013611:Tachycardia, Atrioventricular Nodal Reentry / Q000175:diagnosis* / Q000503:physiopathology
D000889:Anti-Arrhythmia Agents; D000241:Adenosine