Atrioventricular conduction in dogs during anesthesia with isoflurane.

The effects of 1.25, 2.0, and 2.5 MAC isoflurane on atrioventricular conduction were studied by His-bindle electrocardiography during atrial pacing in ten dogs. No effect upon atrioventricular conduction as evidenced by changes in A--H interval (the time of conduction from low right atrium to His-bundle, representing primary AV nodal conduction) was found at these concentrations. Atrial pacing to 200 beats/min did not influence the A--H interval at the three anesthetic concentrations. The stability of cardiac rhythm observed clinically with isoflurane may be related to this lack of effect upon the AV node.