犬急性心肌缺血区CO_2激光孔道的形态学变化

Histological Features of the CO_2 Laser-created Channels in Animal Models of Acute Ischemia

目的观察CO2激光对犬急性心肌缺血行心肌打孔后孔道的形态学变化,以探求TMLR的供血机制。方法8只杂种犬采用冠状动脉结扎方法造成左室前侧壁心肌梗死或缺血。使用大功率CO2激光在心肌缺血区域打孔,打孔数目3～5个/cm2,分别在TMLR后1周、1和6个月将犬心脏取出,经相应组织学方法处理后进行光镜和扫描电镜观察。结果孔道刚建立时可见气化孔道、炭化焦痂、坏死带及变形细胞层由内向外依次排列;TMLR后1周时孔道开放,孔道边缘有炎细胞浸润,1及6个月孔道内壁光滑,孔道与其它心肌结构相连,同时孔道周围的心肌微循环结构较前丰富。但孔道内壁的变化及炎症反应的程度与激光脉冲时间有关。结论TMLR后激光心肌孔道可以较长期保持通畅,使心腔内的氧合血通过这些孔道灌注心肌。但激光脉冲时间和心壁压力大小对孔道的通畅影响较大。

Objective Transmyocardial laser revascularization(TMLR)is a modern approach in the treatment of patients with chronic ischemic ca rdiac disease.The histological features of CO 2 laser created channels after transm yocardial laser therapy have not been described previously.The purpose of this experiment is to study the histologic characteristics of laser created channels after TMLR in animal models of acute ischemia.Methods Acute myocardial ischemia was created by multiple ligation of the coronary artery in 8dogs.The laser procedu re was performed on the animals by beating heart using high power CO 2 laser.Channels were created in the a rea of interest(3-5holes /cm 2 ).The animals were sacrificed at 7day,1month and 6months after TMLR,respectively.The laser -created channels in unfixed and formalin -fixed tissue were grossly located.The laser -tre ated areas were excised and cut lengthwise for histological investigati on with established staining method.In addition,some of tissue specimen s were observed with scanning electr onic microscopy.Results Immediately after application of th e laser,four concentric zones(vaporization,carbonization,fixation,and transition)could be distinguished along the transmyocardial path.Up to 6months,laser induced channels remained patent,and th e containing red blood cells were surrounded by solid tract of con nective tissue.Direct communications were observed between some of the channels and ventricular cavities.Conclusions The laser channels remained patency6months after TMLR.The laser patency channel features were related to la ser pulse width and intramyocardial pressure.