两种激光致心肌血管重建的组织学效应

目的；研究两种激光在心肌血管重建术（TMR）中的组织学效应。方法：实验犬随机分为2组：连续波CO2激光组（n=20）及调制Nd：YAG激光组（n=10），2组均经心外膜法行激光打孔，观察激光孔道的组织学改变。结果：CO2激光孔道周围出现明显的碳化带、凝固性坏死层及心肌变性层，经8周的修复，出现不同程度的微循环改建，尤以碳化程度轻的部位为著；而Nd：YAG激光孔道未见碳化物形成，凝固性坏死及心肌变性范围明显减小，术中并发症的发生均较CO2激光减轻。结论：Nd：YAG激光孔道的热损伤程度轻，有利于心肌内微循环改建，以改善心肌供血，且具有术中并发症少等优点。

HISTOLOGIC EFFECTS OF TRANSMYOCARDIAL REVASCULARIZATION CAUSED BY TWO TYPES OF LASER

Objective: To compare histologic changes induced by transmyocardial revascularization (TMR) with CW-Wave CO2 laser and modulating Nd: YAG laser. Methods: Thirty dogs were randomly divided into two groups: CO2 laser group (n = 20) and modulating Nd: YAG laser group (n = 10). All animals underwent left anterolateral thoracotomy in the fifth intercostal space. Two types of laser were separately used to create channels from the epicardium to the left ventricular lumen. Histomarphologic changes were examined six hours after the procedure. Results: Coagnlative necroses, degenerations and carbide were observed in the myocardium neighboring channels created by CO2 laser. After 8 weeks of lesion repair, intramyocardial angiogenesis could be found in the area with less carbide. Less coagulative necroses and degenerations were observed in the myocardium neighboring the channels created by Nd: YAG laser compared to CO2 laser therapy. No carbide was observed with Nd: YAG laser therapy. Fewer complications were associated to Nd: YAG laser therapy compared to CO2 laser therapy. Conclusion: Nd: YAG laser therapy induces less thermal damage to the myocardial fibres surrounding the channels than CO2 laser therapy. This may promote angiogenesis in the treated region and improve blood flow in the myocardium. This technique has also the advantage of being safe with fewer coeplications.