| Objective:Cardiac arrest(CA)is a vital emergency,which needs to be immediately treated with cardiopulmonary resuscitation(CPR).However,the survival rates of patients always descend because malignant arrhythmia,such as ventricular fibrillation(VF)or ventricular tachycardia(VT),often happened after CPR.It is important to identify and prevent malignant arrhythmia after CPR in time. Recently,some studies showed that both the prolonged QT interval and short QT interval would make the heart prone to malignant arrhythmia.But it maintains unclear that the relationship between the alteration of the QT interval and malignant arrhythmia(MA)before and after CPR.The purpose of this study was to determine the relationship between alteration of the QT interval and MA before and after CPR in a rabbit model of VF so as to provide useful evidence for the further researches.Method:1.Thirty-six healthy rabbits of both sexes,weighing 2.25～2.68 kg,were enrolled in this study.Six synchronous electrocardiogram machine was used to record electrocardiogram in anaesthetized rabbits.2.Establishment of rabbit model of VF.VF was induced in 36 healthy rabbits via percutaneous alternating current stimulation(30V/50HZ,lasting for 30 seconds)and CPR was initiated following 4 min of onset of VF.we have been monitoring the successive changes of ECG and the hemodynamics for 1 hour after ROSC.The rabbits with ROSC were divided into malignant arrhythmia group and non-malignant arrhythmia group according to if they happened the malignant arrhythmia(VT or VF)after successful resuscitation. Then,six synchronous electrocardiogram were measured at the exact point of ROSC,15 min,30 min,45 min and 60 min after ROSC in both oftwo groups. Two groups of electrocardiogram's numerical value of QT interval were measured respectively to compare each other in the different time point before or after the rabbits performed CPR.Result:1.Twenty three of 36 rabbits successfully returned the spontaneous circulation and stepped into the further experiment.Meanwhile,the rest 13 rabbits without ROSC were excluded from the study.VT or VF occurred in 7of 23 rabbits with ROSC who were divided into the malignant arrhythmia group and the rest 16 rabbits with ROSC into the non-malignant arrhythmia group. Both the survival rate and the survival time was higher in non- malignant arrhythmia group than in malignant arrhythmia group.The survival rate was significantly(P＜0.05)higher at 15 min,30min,45min and 60min in the non-malignant arrhythmia group versus the malignant arrhythmia group(non-malignant group:87.6%,87.6%,68.8%and 62.5%versus malignant group:42.9%,14.3%and 0).Survival time in non-malignant arrhythmia group was longer than that in malignant arrhythmia group.2 The QTc interval of the malignant arrhythmia group was significantly shorter(p=0.000)at the exact point of ROSC(0.2516±0.0158s)versus the time before inducing VF(0.3083±0.0218s).Until 15min after ROSC,the QTc interval(0.3267±0.013s)was level with the time before inducing VF.There was no statistic difference among the QTc intervals at the respective time point of the non-malignant group.The QTc interval was significantly shorter(p=0.012) at the exact point of ROSC of the malignant arrhythmia group versus the non-malignant arrhythmia group and no statistic difference among the other time points between the two group.3.The QTpc interval of the malignant arrhythmia group was significantly shorter(p=0.000)at the exact point of ROSC(0.1626±0.0823s)versus the time before inducing VF(0.2400±0.0747s).Until 15min after ROSC,the QTpc interval(0.2183±0.0255s)was level with the time before inducing VF.There was no statistic difference among the QTpc intervals at the respective time point of the non-malignant group.The QTpc interval was significantly shorter (p=0.013)at the exact point of ROSC of the malignant arrhythmia group versus the non-malignant arrhythmia group and no statistic difference among the other time points between the two group.4.The corrected T peak-T end interval of the malignant arrhythmia group was significantly longer(p=0.021)at the exact point of ROSC(91.08±4.36s) versus the time before inducing VF(65.02±7.76s).At 15min after ROSC, corrected T peak-T end interval(108.84±28.60s)was still significantly longer (p=0.005)than the time before inducing VF.There was no statistic difference among the corrected T peak-T end intervals at the respective time point of the non-malignant group.There was no statistic difference in the corrected T peak-T end intervals among the other time points respectively between the two groups.Conclusion:1 In this model of rabbit ventricular fibrillation,the malignant arrhythmia occurred at the early ROSC is one of the important reason to cause the early death of resuscitated rabbits. 2 The QTc interval and the QTpc interval of the rabbits with the malignant arrhythmia were significantly shorter at the exact point of ROSC than the time before inducing VF,and the corrected T peak-T end interval of them were significantly longer at the exact point of ROSC and 15min after ROSC versus the time before inducing VF.Above of these showed that the distinguished changes happen on the QT interval can be taken as important predictors of the occurrence of the malignant arrhythmia after the CPR early.Moreover, prolongation of the corrected T peak-T end interval is possible more sensitive than the changes of the QTc interval or the QTpc interval.3 It is unclear for the detailed mechanism in the alteration of the QT interval,QTp interval and the Tpeak-Tend interval.However,both the global hypoxia and the changes of nerrohumor' factors probably take part in it. |
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