左心辅助装置实验山羊三例死亡分析

Mortality Analysis of 3 Goats with Left Ventricular Assist Device Experiment

目的探讨左心辅助装置(LVAD)实验山羊3例的死亡原因。方法 3例健康成年雌性山羊体重30～48 kg,经左侧第4肋间隙开胸,心尖部植入LVAD,实行左心室辅助。术中和术后持续监测动物临床生命体征、全血活化凝血时间(ACT)、血象、血气及血清生化指标,并给予补液、抗感染、抗凝治疗。动物循环系统或呼吸系统活动停止6 min以上被确定为死亡。动物死亡后随即进行解剖取组织样本做常规病理学检查。结果 3例实验山羊LVAD安装手术顺利,术中监测当LVAD转速达8000～10 000 r/min可维持实验山羊的正常血压。其中2例麻醉停药10 min后恢复自主呼吸。例1实验山羊,术后15 min即可站立,19～27 h采食少量青饲并有反刍现象,术后血浆游离血红蛋白著高于正常值,并排血红蛋白尿,提示红细胞严重破坏。术后第1、2天查尿素、肌酐增高,提示肾功能损害。28 h时术部创口开始渗血,41.7 h时死亡。例2实验山羊,术后不能自行站立,短暂气胸,体温低,排水样粪便,5～7.5 h采食极少量青饲并有反刍现象,术后血浆游离血红蛋白、尿素、肌酐显著高于正常值,提示红细胞严重破坏、肾功能损害。10 h时术部创口开始渗血,19.5 h时死亡。例3实验山羊术中远端血管吻合口吻合不良,致术中大量出血;同时辅助装置测压孔(测左心室压力)金属连接不完善,致输出端漏气,左心室内气栓形成,心脏停搏,实施手术3.5 h时死亡。结论成年山羊可作为LVAD实验动物模型,胸内术部出血和气栓形成是导致实验动物术后近期死亡的主要原因。改进LVAD植入各连接管道的工艺制作、提高血管吻合技巧和早期抗凝治疗等都可有效提高实验动物存活率。

Objective To explore death causes of 3 goats with left ventricular assist device （LVAD） experi- ment. Methods Three healthy adult female goats, which weight were 30-48 kg, underwent thoracotomy through the left fourth intercostal space, 1VAD implantation in the heart apical and left ventricle assistance. Vital signs, whole blood acti- vated clotting time （ACT）, hemogram, serum biochemical indicators of the clinical animals during and after operation were detected, and fluid replacement, anti-infective and anticoagulant therapies were also performed. Circulatory or re- spiratory system abeyance for more than 6 min in animal could confirm the death, and then routine pathological examina- tion for sample was performed after animal death. Results LVAD were successfully installed in three experimental goats, and experimental goats could maintain normal blood pressure when rotation speed of LVAD was up to 8000- 10 000 r/min. Two goats recovered spontaneously breathing after narcotic withdrawal for 10 rain. Another one could stand up at postoperative 15 min, it could feed a small amount of forage and was seen a rumination during the 19-27 h. After surgery, plasmic free hemoglobin significantly higher than that of normal value, and hemoglobinuria discharged which showed that RBC was severely damaged. The values of urea and creatinine increased at postoperative 1st and 2da d which hinted renal functional lesion. Surgical wounds started errhysis after postoperative for 28 h, and it died after postoperative for 41.7t h. The second experimental goat could not stand up after surgery with short pneumothorax, low body temperature and watery feces, and it could feed very small amount of forage with a rumination during the next 5-7.5 h. The values ofpostoperative plasmic free hemoglobin, urea and creatinine were significantly higher than that of normal value, which showed that RBC severe destruction and renal functional lesion. Surgical wounds started errhysis after postoperative 10 h, and it died after 19.5 h. The third experimental goat had an intraoperative massive bleeding induced by distal blood ves- sels inappropriate anastomosis; at the same time, metal connector of pressure tap of assistive devices （for monitoring the left ventricular） was imperfect which induced the outfan leakage, air embolism formation in the left ventricle and heart- beat stop. The goat died during operation for 3.5 h. Conclusion Adult goats can be used as LVAD experimental animal models, and bleeding in the chest and air embolism formation are the main reasons of recent mortality in experimental ani- mals. The survival rate of experimental animals may be effectively improved by improving implantable connecting tubes technology of LVAD, anastomosis techniques of surgical blood vessels and early anticoagulant therapy, etc.