Study In Preventing And Curing Arrhythmia By Benazepril In Rats Of Normal And Dated Myocardial Infarction

Objective:Observe the effect of Benazepril on emergence and persistence time of arrhythmia in rats of normal and dated myocardial infarction,discuss the action of the drug on antiarrhythmia.Methods:Wistar rats were anaesthetized with 10%hydro-chloro-aldehyde(300mg/kg), tracheotomy intubation,left anterior thoracotomy through 3,4 intercostal region were performed,ligating the left anterior descending coronary artery to make animal model of myocardial infarction in rats.The normal rats were divided into 4 groups randomly,injecting isotonic Na chloride and 0.2%BaCl₂(0.2mg/kg,0.4mg/kg,0.8mg/kg)through vein to make animal model of arrhythmia in rats,and recording the types,the emergence and persistence time of arrhythmia in 15 minutes.The rats of normal and myocardial infarction were divided into 4 groups randomly, respectively,the first groups were given to isotonic Na chloride,the second,third and fourth groups were treated with Benazepril(A:0.47mg/kg,B:0.93mg/kg,C:1.86mg/kg,which be equal to adult dose 5mg/60kg,10mg/60kg,20mg/60kg).After 4 weeks,injecting 0.2%BaCl₂ (0.4mg/kg)through vein,and recording the types,the emergence and persistence time of arrhythmia in 15 minutes.Results:After ligating the left anterior descending coronary artery,ST segment of limb lead arise(ST≥0.2mv)in the electrocardiogram monitoring.Rat mortality was 11.00%in operation, the mortalities in 72 hours,1 to 2 weeks and 2 to 3 weeks after operation were 12.87%,7.92% and 4.95%,the survival rate was 63.37%beyond 3 weeks.Rechecking ECG in 3 weeks,the waveshap were Q or QS.Opening cavitas thoracis after 4 weeks,infarction region was thinner,pale,instead of scar tissue,uninfarction region had myocardial hypertrophy,the left ventricular chamber broaden.Injecting isotonic Na chloride and 0.2%BaCl₂ through vein,observed about 15 minutes,the isotonic Na chloride couldn't induce arrhythmia;BaCl₂(0.2mg/kg)could only induce ventricular extrasystole(VE);BaCl₂(0.4mg/kg,0.8mg/kg)all could induce ventricular tachycardia(VT), the former could become sinus rhythm in 15 minutes,the latter couldn't,and the emergence time of VT between two groups didn't have statistical difference(P＜0.05).Rats of normal and dated myocardial infarction wew injected BaCl₂,every rats were induced VT,but the emergence time of VT didn't have statistical difference(P＞0.05).In two experiments,compared with A,NS groups,the persistence time of VT didn't have statistical difference(P＞0.05);the persistence time was shorter in B,C groups than in A,NS groups, which had statistical difference(P＜0.05);compared with B,C groups,the persistence time also had statistical difference(P＜0.05).Conclusion:Ligating the left anterior descending coronary artery can make stable animal model of myocardial infarction in rats,exact ligation position,standard operation and tend after operation was the key of the higher livability.Injecting BaCl₂ of definite dose through vein can induce VT and produce stable animal model of ventricular arrhythmia in rats.The Benazepril in the treatment range can effectively reduce the persistence time of VT induced by BaCl₂ in rats of normal and dated myocardial infarction,and adding dose can increase the effect,but can't extend the emergence time.