| The use of isoproterenol as an adjuvant to high-dose epinephrine in asystolic patients may increase the likelihood of return of spontaneous circulation (ROSC), shorten the time interval from administration of isoproterenol to ROSC, and prolong the time from ROSC to death. But the effects of combined isoproterenol and epinephrine on hemodynamics in cardiopulmonary resuscitation (CPR) is not reported, so we contrast the curative effect of H-Epi and H-Epi+Iso on the resuscitation of dogs' sudden heart arrest made by coronary artery ligation and the effect on hemodynamics. Materials and methods: twenty-four northeast hybrid dogs, weight 14~22 kg, were randomized into three groups. group I: control group, treated with routine-dose epinephrine (Epi) 0.02mg/kg every time by intravenous injection; group II: treated with high-dose epinephrine (H-Epi) 0.2mg/kg every time, iv; group III: treated with Epi 0.2mg/kg and Iso 0.02mg/kg every time intravenous injected, which is called H-Epi+Iso group. The animal model of acute myocardial infarction and thereafter ventricular fibrillation (Vf) was made. Epinephrine and isoproterenol were used according to the grouping and electric conversion was used. If conversion was defeated we repeated intravenous drug and electric conversion, every dog had 2 to 3 times of Vf. We observe the following items: 1) Observe the II lead and epicardium electrocardiogram (ECG), detect the time from coronary ligation to the emerge of Vf and the time of ROSC persisting, and observe the ROSC's ECG manifest; 2) Detect LVSP, LVEDP, ±dp/dt max, MAP; 3) Detect the dose of drug that was used to make conversion emerged and the odds of conversion.Results: There was no significant difference between the three groups as the time of Vf emerging concerned (P>0.05). The conversion odds and the ROSC persisting time of the H-Epi+Iso group were significantly superior to those of H-Epi group. The ventricular arrhythmia of H-Epi+Iso group was not increased significantly after conversion. The sinus bradycardia and III°AVB, emerged in H-Epi group and H-Epi+Iso group, were converted to sinus rhythm after Iso was used. We detected that LVEDP increased, ventricular rate increased, ±dp/dtmax and MAP decreased in all the three groups, and there was no significant difference between the three groups as the above concerned. After Vf conversed there was no significant difference between the three groups as the effect of conversion on LVSP concerned, but LVEDP increased significantly and ±dp/dtmax increased significantly in H-Epi group and H-Epi+Iso group contrasted to Epi group (P<0.05), and the above change was more significant in H-Epi+Iso group (P<0.05). After Vf conversed the MAP of H-Epi group was higher than that of Epi group, the MAP and heart rate of H-Epi+Iso group hardly changed. Conclusion: The sudden heart death of coronary heart disease patients is usually coming from ventricular tachycardia and Vf, the combined treatment of electric conversion and drugs is very important to CPR. Epinephrine is preferred in the course of CPR, but the dose of Epi is still a discussion focus to clinic. Iso is advocated to be use only as combined with Epi, because it is a stimulant of β–receptor. In this research we made animal model of Vf after coronary ligation, and used routine dose of Epi, high dose of Epi and high dose of Epi combined with Iso in three groups. The result manifested that the odds of conversion and the time of ROSC persisting of H-Epi group is superior to those of Epi group (70.0%vs58.5%, 39.25±63.6 min vs 27.8±20.7min, P<0.05), which is accord with the latest clinical report. When the dose of Epi is equal, the odds of conversion of H-Epi+Iso group is increased contrasted to H-Epi group (80.95% vs 70.0% P<0.05) and the ROSC persisting time of H-Epi+Iso group is prolonged contrasted to H-Epi group (59.83±105.9 min vs 39.25±63.6min). The sinus bradycardia and III°AVB emerged after conversion, but were converted to normal sinus rhythm after the use of Iso, without ventricular tach...
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