激光心肌打孔缓解心绞痛的机制探讨

A possible mechanism of relief of symptoms by transmyocardial laser treatment for angina pectoris

目的探讨心肌激光打孔术(TMLR)后早期心绞痛症状改善的可能机制。方法健康杂种犬20只,随机均分为4组。Ⅰ组切开心包后不作任何处理,Ⅱ组采用冠状动脉结扎法建立心肌缺血模型,Ⅲ组在建立缺血模型40min后采用高功率CO2激光对缺血心肌进行TMLR,Ⅳ组于左室相应区域心外膜表面涂擦85%苯酚溶液去除局部神经结构。2周后二次开胸取出心脏制作心肌标本,行免疫组化染色分析交感神经结构及功能,HE染色观察各组心内膜下心肌结构。结果免疫组化分析示Ⅰ组为强阳性,Ⅱ组阳性,Ⅲ组弱阳性,Ⅳ组阴性,图像分析示Ⅲ、Ⅳ组光密度值明显低于与Ⅰ、Ⅱ组(P<0.05)。HE染色Ⅲ组心肌缺血表现与Ⅱ组比较改善不明显。结论TMLR破坏了心脏交感神经及串行于其内的感觉神经,而无明确的心肌缺血改善的证据;TMLR术后早期临床症状的改善可通过疼痛传导阻滞来解释。

Objective To explore the mechanism of relieving syrnptorns of angina pectoris with transmyocardial laser treatment. Methods Twenty mongrel dogs were divided randomly into 4 groups （5 dogs each） ： Ⅰ. sharrroperated negative control animals undergoing thoracotomy and pericardiotomy only; Ⅱ. ligation of the coronary arteries to create acute myocardial ischemia; Ⅲ 40 minutes after production of acute myocardial ischemia, transmyocardial punctures were made with high power CO2 laser;Ⅳ. chemical destruction of cardiac nerves by application of 85% phenol to the epicardium after myocardial ischemia. The myocardium was harvested for examination 2 weeks later. Cardiac sympathetic afferent nerve function and innervation was assessed with immunohistochemical staining of tyrosine hydroxylase （TH）, which was the specific enzyme of sympathetic nerves, and computer image analysis was done. Histopathological changes in myocardium were also evaluated with haematoxylirveosin staining. Results Immunohistochemical analysis showed positive staining in Ⅰ and Ⅱ groups but negative or weakly positive in Ⅲ and Ⅳ groups. Computer image analysis showed the same results, and there was significant difference among Ⅰ, Ⅱ and Ⅲ, Ⅳ groups （P〈0. 05）. HE staining showed no evidence in improvement of myocardial ischemia after laser puncturing. Conclusion Transmyocardial laser treatment destroys cardiac nerve fibers, including sensory nerve which is contained in sympathetic nerves. TMI.R cannot improve myocardial perfusion. Symptomatic improvement of angina pectoris after TMI.R could be attributed to de struction of cardiac nerve fibers.