| Background There were many victims died of cardiogenic sudden death and the leading cause was ventricular fibrillation(VF).The most effective treatment for VF was electric defibrillation. The mechanism of ventricular defibrillation was the shock electric field interacts with myocardium cells were not in absolute refractory and enforced these cells depolarizing and turning into refractory period. Then this myocardium could not response the new stimulation from the other myocardium excitation. If there were enough myocardium cells being in refractory period, the ventricular fibrillation would stop. Time to defibrillation was the most important determinant of survival from cardiac arrest.Recent developments in automated external defibrillator technology had provided a means of increasing the rate of prompt defibrillation after out-of-hospital cardiac arrest.But in china, there were not AED developed by our own country. Secondly, the defibrillation efficiency could effect by wave-shape, impedance, size or placing of electrode pads, pulse duration and so on. So for each factor we could find optimal one to improve the defibrillation efficiency and decrease the energy requirement.This study completed the development of AED by our own team and we took some animal experiment on low energy defibrillation.Objective The aim of this study was to develop new automated external defibrillator(AED), evaluate the recognition efficiency of this new AED and explore the effect of pulse duration on efficacy of ventricular defibrillation by animal experiment.Methods AED consists of the part of defibrillation ,monitor and correlated software. This AED use the standard biphasic truncated exponential waveform . The algorithm which designed by our team has self-studying and self-adjustment function. In animal experiment, the pigs were induced ventricular fibrillation through alternating current(AC),then recorded the AED's recognition of ventricular fibrillation and calculated the sensitivity and specificity .then the pigs randomly received defibrillation with biphasic waveforms which pulse duration was 4ms+1ms+4ms or 5ms+1ms+5ms.Defibrillation thresholds (DFTs) and success rates were determined and analyzed by statistics.Results The new AED can analyse ECG coming from one of three channels; through the self-studying ,the device can decide the threshold of each parameter and it can adjust the threshold according to the changes of the ECG signals. Defibrillation waveform is biphasic truncated exponential waveform ,negative and positive pulse duration are 5ms. There were induced VF 96 episode and all pigs underwent 145 defibrillations.we recorded electrocardiosignal 103740 seconds. The sensitivity and specificity of our AED on the recognition were 98.2% and 99.6%,the accuracy and positive predictivity were 99.5% and 95.5% .In the defibrillation experiment, There were induced VF 81 episode and 26 of them achieved success.The two groups had no significant difference on total shock voltage and energy.But the defibrillation threshold of energy and electric quantity of 4ms+1ms+4ms group were lower compare with 5ms+1ms+5ms group(8.582±2.246J Vs 9.024±4.443J, p=0.025; 0.032±0.007 Vs 0.036±0.005C, p=0.019).Conclusion The AED that developed by our own has very high sensitivity and tspecificity on recognizing VT/VF , the algorithm of our AED fulfills the requirement of early defibrillation.It also has high efficiency of defibrillation. Compared with the same kinds products from abroad ,our AED has achieved the similar or superior performance on many aspects. The pulse duration is an important influence factor for defibrillation efficacy and we may decrease DFTs by shortening the pulse duration.
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