Propofol does not affect the canine cardiac conduction system under autonomic blockade

Abstract

Purpose: To determine the effects of propofol on the cardiac conduction system in dogs with pharmacological autonomic blockade. Methods: In eight mongrel dogs receiving 6 mg'kg -l'hr -I propofol and vecuronium under pharmacological autonomic blockade with atropine and propranolol the infusion rates of propofol were increased from 6, (baseline), to 12, 18 and 24 mg'kg -i'hr -l at 60-min intervals. An electrophysiological study assessed sinus rate, sinus node recovery time, corrected sinus node recovery time, intraatrial conduction time, AV nodal effective refractory period, Wenckebach cycle length and AV conduction times. Electrocardiographical variables and arterial pressures were also measured. All measurements were repeated at 30 min after the beginning of each infusion of propofol. Re~uJts: Propofol did not produce direct effects on the electrophysiological or electrocardiographical variables at any infusion rates. Heart rates did not change at higher infusion rates in the presence of decreases in arterial pressures. Conclusion: Propofol did not affect the cardiac conduction system in the presence of autonomic blockade. Thus, the direct cardiac effects of propofol do not play a causative role in the genesis of propofol-associated bradyarrhythmias.Objectif: DEterminer les effets du propofol sur le syst~me de conduction du coeur chez les chiens soumis ~ un blocage nerveux autonome. M&hode : I'&ude a porte sur huit chiens communs qui ont re~ju 6 mg-kg -I-hr t de propofol et du v&uronium sous un blocage pharmacologique nerveux autonome avec de ratropine et du propranolol. La vitesse de peffusion du propofol a augment& passant de 6, au depart, ~ 12, 18 puis 24 mg-kg -~'hr -I ~ des intervalles de 60 min. Un examen Electrophysiologique a permis d'Evaluer le rythme sinusal, le temps de rEcupEration sinusale, le temps de rEcupEration sinusale corrig& le temps de conduction intra-auriculaire, la pEriode rEfractaire effective clu noeud AV, la Iongueur de la p&iode de Wenckebach et les temps de conduction AV. On a aussi mesurE les variables Electrocardiographiques et les pressions artErielles. Toutes les mesures ont EtE reprises 30 min aprEs le debut de chaque perfusion de propofol. l~.~ultats : Le propofol n'a pas eu d'effet direct sur les variables ~lectrophysiologiques ou Electrocardiographiques, r&ultat valable pour route vitesse de perfusion. Les frEquences cardiaques front pas change pendant les perfusions les plus rapides en pr&ence de baisses de pression artErielle. Conclusion: Le propofol n'a pas affect6 la conduction cardiaque en presence d'un blocage nerveux autonome. Par consequent, les effets directs du propofol sur le coeur front pas eu de r61e causal dans I'apparition des bradyarythmies qui lui Etaient associEes.

Effects of Propofol on Electrocardiogram Measures in Mice

“…A suppressive effect of propofol has been reported on human sympathetic nerve activity (10), with similar effects observed in rat and rabbit models (11,12). However, no suppressive effect was detected in dogs (13).…”

Conversion of supraventricular arrhythmia to normal rhythm by propofol and remifentanil: three cases report

“…Propofol induces bradycardia originating from an intense reduction of the sympathetic tone [7]. Ikeno et al [8] reported that propofol did not affect the CCS when the autonomous nervous system (ANS) was blocked with atropine prior to the administration of propofol in dogs. These reports support the assumption that propofol affects the ANS, suppressing tachycardia and triggering bradycardia.…”

“…Zaballos et al [10] reported that the electrophysiologic synergic interaction between propofol and remifentanil could be excluded. However, both drugs can change the autonomic nervous system tone [7,8,12]. Thus it is plausible that both drugs may affect the tone additively or synergistically.…”

Efeitos do propofol sobre o sistema de condução cardíaca

“…In studies with dogs, any effect on the CCS was not observed when in the presence of ANS blocked induced by atropine and propranolol before the administration of propofol 21 .…”