起搏阈值测量用兔心肌梗死模型的制备

ESTABLISHMENT OF MYOCARDIAL INFARCTION MODEL OF RABBITS FOR THE MEASUREMENT OF PACING THRESHOLD

目的探讨起搏阈值测量用兔心肌梗死模型的制备方法。方法健康新西兰大白兔27只,随机分为5组,其中A组(高剂量利多卡因组)7只;B组(中剂量利多卡因组)4只;C组(低剂量利多卡因组)5只;D组(美托洛尔静脉注射组)3只;E组(美托洛尔饲喂组)8只。结扎各组冠状动脉左回旋支(left circumflex arteries,LCA)中点建立心肌梗死模型,除E组术前1 h给药外,其余各组均于结扎后1 min内静脉注射相应药液,并于结扎前及结扎后10、20、30、40、50、60、75、90、105、120、140、160、180、200、220、240、260、280、300main给予电信号刺激,统计观察各组降心率效果、抗心律失常作用及病死率。结果 A、B组易诱发不良事件(心律失常或死亡),与其余组比较差异有统计学意义(P<0.05);C组不易诱发不良事件,低心率维持较短时间;E组未诱发不良事件,且低心率维持时间最长,与其余组比较差异有统计学意义(P<0.01);D组注射后10 min内均未见明显改变。结论于开胸结扎LCA中点前1 h饲喂美托洛尔4～6mg/kg,失效后于测量前静脉注射利多卡因2.0 mg/kg,可成功建立起搏阈值测量用兔心肌梗死模型,该方法快捷、简易、成功率高。

Objective To establish the myocardial infarction （MI） model of rabbits for the measurement of pacing threshold. Methods Twenty - seven rabbits were randomly assigned into five groups ： group A （ high dose lidocaine group, n = 7 ）, group B （ moderate dose lidocaine group, n = 4 ）, group C （low dose lidocaine group, n = 5 ）, group D （metoprolol iv group, n = 3 ） and group E （metoprolol po group, n = 8）. Only group E had taken drugs 1 hour before their left circumflex arteries （LCA） being ligated , others received intravenous injections 1 minute later. Electrical stimulation was given to the infarcted myocardium at baseline, 10,20,30,40,50,60,75,90,105,120,140,160,180, 200,220,240,260,280 and 300 minutes after the ligation, respectively. Heart rate, ventricular fibrillation rate and mortality rate were measured to evaluate the heart rate reduction and stability of MI model in each group. Results The adverse events such as ventricular fibrillation or death occurred more often in high and moderate dose lidocaine group （ P 〈 0.05 ） ; A short - term reduce of heart rate and less adverse events happened in low dose lidocaine group; Lower heart rate was maintained longest in metoprolol po group （P 〈 0.01 ）, and no adverse events appeared. While, in metoprolol iv group, there was no significant change in heart rate within 10 minutes. Conclusion Gaving metoprolol 4 -6mg/kg 1 hour before the LCA ligation and lidocaine 2.0mg/kg when metoprolol lose potency is a rapid, simple, and effective method to establish the MI model of rabbits for the measurement of pacing threshold.