犬重度心肌挫伤后早期左心功能损伤的实验研究

目的制备一种适合于临床研究所用的重度心肌挫伤动物模型,观察心肌挫伤后早期左心功能损害的程度及变化规律.方法选取杂种犬9只,采用BIM-Ⅱ型水平撞击机制成MC模型.分别于伤前、伤后即刻、2h、4h和8h常规监测动物生命体征的变化,经右颈总动脉插管监测左室收缩与舒张功能变化.常规病理组织活检及TTC染色验证心肌损伤的程度.结果犬重度心肌挫伤后心率呈持续降低,平均动脉压(MAP)伤后即刻降低,4、8h有明显升高.中心静脉压(CVP)伤后呈持续性升高至8h未恢复正常.左室收缩末期压力(LVESP)伤后即刻降低,2、4、8h增高,左心室内压上升最大速率( dp/dtmax)伤后持续增加.而左室舒张末期压(LVEDP)伤后持续增高,左心室内压下降最大速率(-dp/dtmax)伤后持续降低.病理组织活检证实,心脏损伤表现为心外膜下可见少许点状出血,心内膜下可见散在或片状出血,最常见损伤部位依次为心尖部、左室间隔面心内膜下及近乳头肌处、左心房、右室间隔面心内膜下和右心房.结论 (1)BM-Ⅱ型撞击机所致犬重度心肌挫伤模型稳定、可靠、重复性良好;(2)犬重度心肌挫伤后主要以左室舒张功能损害为主,收缩功能损伤较轻.

Experimental study on the early injuries of left ventricular function of dogs with severe myocardial contusion

Objective To establish an animal model of severe myocardial contusion (MC) that is practically useful for clinical studies, and to investigate the degree of severity and also the changing regularity of left ventricular functional injuries after MC.Methods Nine mongrel dogs were selected and then impacted to establish myocardial contusion model. Life signs of these dogs were conventionally monitored at time points as before wounding, instantly post wounding, 2h, 4h and 8h after wounding. The right common carotid artery was catheterized to monitor the changes of systolic and diastolic functions of left ventricle. Pathological biopsy was made at the end of experiment, and TTC staining was also made to confirm the degrees of injuries.Results After severe MC, heart rate of dogs presented a continuous decrease, mean arterial pressure (MAP) decreased instantly and obviously increased at 4h and 8h. Central veinous pressure (CVP) increased constantly till 8h after wounding. Left ventricular end systolic pressure (LVESP) decreased instantly and increased constantly from 2h to 8h post-wounding, while dp/dtmax increased constantly from 0h to 8h post-wounding. Left ventricular end diastolic pressure (LVEDP) increased constantly after wounding, while -dp/dtmax decreased continuously after wounding. Pathological biopsy demonstrated that there were spotty hemorrhage of epicardium and piece-like hemorrhage of endocardium. The most popularly injured sites are apical part, endocardium of interventricular septum of the left ventricular side, left atrium, subendocardium of interventricular septum of right ventricle side and right atrium.Conclusion Severe myocardial contusion of dogs wounded by BM-II impact machine is a stable, repeatable and reliable model. After severe MC, dogs were demonstrated to have severer diastolic functional injuries of the left ventricle, and lighter systolic functional injuries.