Changes in electrical conduction of ventricular myocardium during hypothermic ischemia-reperfusion in rats with arrhythmia / 中华麻醉学杂志

ABSTRACT

Objective:To evaluate the changes in the electrical conduction of ventricular myocardium during hypothermic ischemia-reperfusion (I/R) in rats with arrhythmia.Methods:Healthy clean-grade adult male Sprague-Dawley rats, aged 2-3 months, weighing 200-300 g, were studied.The hearts were removed and retrogradely perfused with oxygenated K-H solution in a Langendorff apparatus. Sixteen isolated hearts were divided into 2 groups ( n=8 each) using a random number table method: normal control group (group C) and hypothermic I/R group (group I/R). In group C, the heart was perfused with K-H solution at 37 ℃ for 120 min.In group I/R, the heart was perfused with K-H solution at 37 ℃ for 30 min, and then perfusion was stopped, cardiac arrest was induced through injecting Thomas solution (4 ℃), the area around the heart was protected with low temperature (4 ℃) Thomas solution, and hearts were perfused with 4 ℃ Thomas solution at 30 min after cardiac arrest and with 37 ℃ K-H solution for 30 min staring from 60 min after cardiac arrest.The rats in group I/R were further divided into high-risk subgroup (I/R-H subgroup) and low-risk subgroup (I/R-L subgroup). The time of spontaneous recovery of heart beat and development of arrhythmia were recorded.At the end of reperfusion, the atrioventricular conduction 2∶1 block point (2∶1B) and ventricular electrical conduction velocity (CV) were measured and recorded by program-controlled electrical stimulation. Results:Compared with group C, CV and 2∶1B were significantly decreased in IR-L and IR-H subgroups ( P<0.05). Compared with IR-L subgroup, the time for restoration of spontaneous heart beat was significantly prolonged, the incidence of ventricular fibrillation and arrhythmia score were increased, and CV and 2∶1B were decreased in IR-H subgroup ( P<0.05). Conclusion:The electrical CV of ventricular myocardium is decreased during hypothermic I/R, which may be the mechanism of reperfusion-induced ventricular arrhythmia in rats with arrhythmia.