Purpose: To determine the effects of propofol on the cardiac conduction sys
tem in dogs with pharmacological autonomic blockade.
Methods: In eight mongrel dogs receiving 6 mg.kg(-1).hr(-1) propofol and ve
curonium under pharmacological autonomic blockade with atropine and propran
olol the infusion rates of propofol were increased from 6, (baseline), to 1
2, 18 and 24 mg.kg(-1).hr(-1) at 60-min intervals. An electrophysiological
study assessed sinus rate, sinus node recovery time corrected sinus node re
covery time, intraatrial conduction time, AV nodal effective refractory per
iod, Wenckebach cycle length and AV conduction times. Electrocardiographica
l variables and arterial pressures were also measured, All measurements wer
e repeated at 30 min after the beginning of each infusion of propofol,
Results: Propofol did not produce direct effects on the electrophysiologica
l or electrocardiographical variables at any infusion rates. Heart rates di
d not change at higher infusion rates in the presence of decreases in arter
ial pressures.
Conclusion: Propofol did not affect the cardiac conduction system in the pr
esence of autonomic blockade, Thus, the direct cardiac effects of propofol
do not play a causative role in the genesis of propofol-associated bradyarr
hythmias.