Effects of hypothermia combined with sevoflurane on myocardial monophasic action potential and transmural dispersion of repolarization of ventricles in rabbits / 中华麻醉学杂志

ABSTRACT

Objective To investigate the effects of hypothermia combined with sevoflurane on myocardial monophasic action potential (MAP) and transmural dispersion of repolarization (TDR) of the left ventricle in rabbits in vitro. Methods Adult rabbits weighing 1.5-2.0 kg were sacrificed after heparinized and anesthetized.The hearts were immediately removed and perfused with K-H soluation saturated with 95%O2-5%CO2 at 37℃ in a Langendorff apparatus. Forty-eight isolated hearts were randomly divided into 6 groups ( n = 8 each) Ⅰ control group (group C), Ⅱ low concentration sevoflurane group ( group S1 ), Ⅲ high concentration sevoflurane group (group S2 ), Ⅳ hypothermia group (group H), Ⅴ hypothermia + low concentration sevoflurane (group HS1 ) and Ⅵ hypothermia + high concentraion sevoflurane (group HS2 ).Group C received continous perfusion. Group S1and S2 received perfusion with K-H solution saturated with 2.4% and 4.8% sevoflurane at 37 ℃ for 30 min respectively. Group H received perfusion with K-H solution at 30℃ for 30 min. Group HS1 and HS2 received perfusion with K-H solution saturated with 2.4% and 4.8% sevoflurane at 30℃ respectively.MAPs of epicardium, mid-myocardium and endocardium of the left ventricle were recorded. MAP duration at 90%repolarization(MAPD90)and TDR were calculated. Early after-depolarization,delayed after-depolarization and arrhythmia were also recorded. Results Compared with group C, MAPD90 of the 3 layers of ventricle was significandy prolonged, the incidence of arrhythmia increased in group H (P＜0.05). There was no significant difference in TDR among all groups ( P＞0.05). There was no interaction between sevoflurane and hypothermia (P＞0.05), and it only showed that MAPD90 was prolonged by hypothermia (P ＜0.05 ). Conclusion Hypothermia combined with sevoflurane exerts no significant effects on myocardial MAP and TDR of ventricles in rabbits, and sevoflurane decreases the incidence of hypothermia-induced arrhythmia through inhibiting the prolongation of MAPD90.