不同频率心房电刺激对犬急性房颤模型的心房电重构影响及安全性分析

Effect and safety of atrial electrical stimulation at different frequencies on atrial electrical remodeling in canine model of acute atrial fibrillation

目的探讨不同频率电刺激对犬急性房颤(AF)模型的心房电重构影响及安全性分析,为AF犬模型制作和AF的机制研究提供理论基础。方法根据刺激频率的不同将实验犬随机分为3组,A组(n=6):400次/分刺激组,B组(n=6):600次/分刺激组,C组(n=6):1000次/分刺激组,分别在基线状态和持续刺激后6、12、18、24、30、36、42、48 h动态测心房有效不应期(ERP)、AF诱发率、AF持续时间和AF易损窗(WOV),评估整个实验过程中是否有感染、休克、心衰、猝死等安全风险。结果在本实验的18只犬中,C组2只分别在快速起搏37 h和40 h出现室颤,抢救无效死亡;另外16只完成整个实验。3组均能诱发房颤。400次/分、600次/分、1000次/分不同的频率均可诱发房颤,快速起搏心房24 h之内,3组ERP进行性下降,18 h内下降趋势更明显,24 h后ERP趋于相对平稳,无进行性下降趋势,3组差异无统计学意义(P>0.05)。3组WOV、房颤诱发率、房颤持续时间均出现增加趋势,差异有统计学意义(P<0.05),但是ERP、WOV、房颤诱发率及房颤持续时间的改变时间段并不完全一致。在整个实验过程中无感染,3组降钙素原差异无统计学意义(P>0.05)。心衰相关性指标NTpro-BNP在C组中随着刺激时间的延长出现升高趋势,3只30 h时明显高于正常值,提示有心力衰竭,3组有统计学差异(P<0.05)。快速起搏心房18 h后,C组收缩压和舒张压均进行性下降,24 h后下降更明显,42 h后2只犬出现休克血压,3组血压变化差异有统计学意义(P<0.05)。结论C组造模时间较短,但是休克、心衰、死亡等风险高于A、B组,在急性模型中,起搏频率设置为400次/分或600次/分较起搏频率设置为1000次/分更安全且有效。

Objective To explore the effect and safety of atrial electrical stimulation at different frequencies on atrial electrical remodeling in canine model of acute atrial fibrillation(AF).It provides the theoretical basis for the establishment of canine model and the mechanism of AF.Methods The dogs will be randomly divided into the three groups according to the stimulation frequency.Group A(n=6):right atrial high-frequency stimulation,400/min;group B(n=6):right atrial high-frequency stimulation,600/min;group C(n=6):right atrial high-frequency stimulation,1000/min.Atrial effective refractory period(ERP),AF induction rate,AF duration and AF vulnerability window(WOV)will be measured dynamically at baseline and 6,12,18,24,30,36,42 and 48 hours after the continuous stimulation.Evaluating whether there will be safety or risks such as infection,shock,heart failure and sudden death during the whole experiment.Results Among the 18 dogs in the experiment,2 dogs in group C developed ventricular fibrillation at 37 h and 40 h of rapid pacing respectively,which were rescue ineffective and died,the other 16 completed the whole experiment.All three groups can induce AF.Different frequencies of 400/min,600/min and 1000/min can induce AF.Within 24 hours of rapid atrial pacing,ERP in the three groups were decreased,and the downward trends were more obvious within 18 hours after 24 hours,and ERP tended to be relatively stable without downward trend,and there was no statistical difference among the three groups(P>0.05).WOV,AF induction rate and AF duration in the three groups showed an increasing trends with statistical difference(P<0.05).However,the change time periods of ERP,WOV,AF induction rate and AF duration were not completely same.There was no infection during the whole experiment,and there was no significant difference in procalcitonin among the three groups(P>0.05).NTpro-BNP was increased with the extension of stimulation time in group C,and it was significantly higher than the normal value at 30 h with suggesting heart failure.There was significant difference between the three groups(P<0.05).After rapid atrial pacing for 18 hours,the systolic and diastolic blood pressure in group C was decreased gradually,and the decreasing was more obvious after 24 hours.Shock blood pressure occurred in 2 dogs after 42 hours,there was significant difference in the changes of blood pressure in the three groups(P<0.05).Conclusion The modeling time of group C is shorter,but the risks of shock,heart failure and death are higher than those of groups A and B.In the acute model,a pacing rate of 400/min and 600/min may be more effective and safe than 1000/min.