房间隔缺损封堵术动物模型在高+Gz歼击机飞行条件下的安全性评价

Safety evaluation of animal model of atrial septal defect occlusion under high+Gz conditions for fighter flight

目的制作房间隔缺损(ASD)封堵术动物模型,探讨高正加速度(+Gz)作用下封堵器的稳定性,为接受ASD封堵术的歼击机飞行员的航空医学鉴定提供依据。方法选取健康西藏小型猪12头,随机分为实验组和对照组,每组各6头。实验组制作ASD模型,选用镍钛合金封堵器经股静脉行ASD封堵术。术后6个月两组通过离心机给予高+Gz暴露。暴露条件为5 Gz/60 s 1次,7 Gz/60 s 3次,9 Gz/60 s 1次,11 Gz/30 s 1次,G值增长率为1 G/s,每次加载间隔5 min。+Gz暴露前后进行心肌标志物、心电图、心脏超声检查,+Gz暴露后24 h处死动物,取房间隔封堵器复合体进行力学拉伸实验。结果①+Gz暴露后与暴露前对比、两组比较,心电图均无显著改变(P>0.05),经胸心脏超声测量左房/右室内径、左室收缩/舒张末期内径、左室收缩/舒张末期容积、射血分数等参数均值也无显著性变化(P>0.05);②+Gz暴露后4、24 h血浆肌酸激酶同工酶、肌钙蛋白I/T、C-反应蛋白、脑钠肽与暴露前对比均明显升高(P<0.05),但两组间比较无显著性差异(P>0.05);③大体解剖和光镜下观察实验组植入的封堵器完好、无移位和损伤;④房间隔封堵器复合体单向拉伸实验显示,复合体均未发生连接部位损伤、撕裂和脱位。结论ASD封堵术动物模型术后6个月,在重复高+Gz暴露下,复合体的稳固性和动物的耐受性良好,可成为ASD封堵后的歼击机飞行员特许飞行的重要依据。

Objective To explore the stability of implanted occluders under high+Gz exposure by making an animal model of atrial septal defect(ASD)occlusion,so as to provide a basis for aeromedical evaluation of fighter pilots receiving ASD occlusion.Methods Twelve healthy Tibetan miniature pigs were selected and divided into experimental group and control group,with 6 pigs in each group.In the experimental group,ASD model was prepared and then closed by atrial septal occluder made by nickel-titanium alloy through femoral vein.Six months after the operation,the two groups were given high+Gz exposure in a centrifuge.The exposure conditions were 5 Gz/60 s 1 time,7 Gz/60 s 3 times,9 Gz/60 s 1 time and 11 Gz/30 s 1 time.The growth rate of G value was 1 G/s,and the loading interval was 5 min.Before and after+Gz exposure,blood samples were collected to measure the changes of myocardial markers,electrocardiogram(ECG)and cardiac ultrasound were performed,and heart samples were collected 24 h later.Mechanical tensile tests were performed on the atrial septal occluder complex,and the tensile curves were recorded and analyzed.Results①There was no significant change in ECG between the two groups after high+Gz exposure,as well as intra-group comparison before and after exposure.There was also no significant difference in the values of parameters of transthoracic echocardiography,including left atrial/right ventricular diameters,left ventricular end systolic/diastolic diameters,left ventricular end systolic/diastolic volumes and ejection fraction before and after high+Gz exposure(P>0.05).②At 4,24 h after high+Gz exposure,the levels of plasma creatine kinase isoenzyme,troponin I/T,C-reactive protein,and brain natriuretic peptide in both groups were significantly higher than those before exposure(all P<0.05),but there was no significant difference between the two groups(all P>0.05).③The ASD occluder implanted in the experimental group was intact without displacement or damage.④The uniaxial tensile test of the atrial septal occluder complex showed that no damage,tear or dislocation occurred at the junction of the complex,and the stress was much lower than the centrifugal force under high+Gz conditions.Conclusion Six months after operation of ASD occlusion,the animal model was testified good safety and tolerability with good stability of the complex under repeated high+Gz exposure,which provided an important support for flight waiver of fighter pilots after ASD occlusion.