Atrioventricular conduction during adenosine-induced hypotension in dogs anaesthetized with sevoflurane

We have studied the effects of adenosine-induced hypotension on A-Hinterval (atrioventricular (AV) nodal conduction time during sinus rhythm),St-H interval (intra-atrial plus AV nodal conduction time during atrialpacing), H-V interval (His-Purkinje conduction time) and H-S interval(total ventricular conduction time) by His-bundle electrocardiography inaddition to surface electrocardiogram during both sinus rhythm and atrialpacing in nine dogs anaesthetized with 1 MAC of sevoflurane. Stepwiseincreases in infusion rates of adenosine to 0.1, 0.3, 0.5 and 1.0 mg kg-1min-1 produced a dose-related decrease in mean arterial pressure from 91(6) to 38 (2) mm Hg. Adenosine significantly increased the A-H interval atinfusion rates of 0.5 mg kg- 1 min-1 and above, and the St-H interval at1.0 mg kg-1 min-1. The H-V and H-S intervals remained unchanged. Heart ratedecreased significantly only at 1.0 mg kg-1 min-1 with a significantincrease in the PR interval. Adenosine-induced hypotension did not havedeleterious effects on AV conduction times and the surfaceelectrocardiogram in dogs anaesthetized with 1 MAC of sevoflurane. This mayindicate that the effects of adenosine on AV conduction were small andtherefore are unlikely to be a contraindication to the use of adenosine forinducing hypotension in patients with initially normal conduction duringsevoflurane anaesthesia.