Lu C H, Yu T J, Lai S T
Division of Cardiovascular Surgery, Veterans General Hospital-Taipei, Taiwan, ROC.
Zhonghua Yi Xue Za Zhi (Taipei). 1999 Sep;62(9):614-8.
Laser transmyocardial revascularization (TMR) appears to improve symptoms in patients with refractory angina. However, it remains a controversial treatment modality for relieving ischemia. We conducted our study in dogs and evaluated the changes in morphology and histology of the myocardium after laser TMR.
The hearts of 10 mongrel dogs (20-30 kg each) were treated with a holmiumyttrium aluminum garnet (YAG) laser in vivo. After opening the pericardium, the 1-mm fiberoptic device was used to create an average of 30 transmyocardial channels per heart at approximate intervals of 0.5 to 1 cm through normal left ventricular myocardium. All dogs tested survived the procedure. The dogs were sacrificed on the first and 60th postoperative days.
In the day-1 postoperative group (n = 4), the transmyocardial channels were obliterated at both epicardial and endocardial ends. The channels were totally occupied by necrotic myocytes and did not appear patent under the microscope. In the day-60 postoperative group (n = 6), the epicardial and endocardial scars were identified at each original laser application site. On cross-section, the channels were invaded by fibrous tissue bands extending from the endocardium to the epicardium, without a prominent central passage. Trichrome stained specimens showed that the channels were replaced by collagen fibers, fat tissue and numerous well-developed capillaries or sinusoids in which plenty of red blood cells were found.
We concluded that laser TMR offers no help for acute myocardial ischemia, but results in neovascularization inside the channels by the 60th postoperative day. Angiogenesis induced by laser TMR could possibly play a role in relieving chronic ischemia.
激光心肌血运重建术（TMR）似乎可改善顽固性心绞痛患者的症状。然而，对于缓解心肌缺血而言，它仍是一种存在争议的治疗方式。我们在犬类动物身上开展了本研究，并评估了激光TMR术后心肌的形态学和组织学变化。
对10只杂种犬（每只体重20 - 30千克）的心脏进行体内钬钇铝石榴石（YAG）激光治疗。打开心包后，使用1毫米光纤装置，通过正常的左心室心肌，平均每颗心脏以约0.5至1厘米的间隔创建30条穿壁心肌通道。所有受试犬均存活至手术结束。在术后第1天和第60天对犬实施安乐死。
术后第1天组（n = 4），穿壁心肌通道在心外膜和心内膜两端均闭塞。通道完全被坏死的心肌细胞占据，在显微镜下未见通畅。术后第60天组（n = 6），在每个最初的激光照射部位可识别出心外膜和心内膜瘢痕。在横切面上，通道被从心内膜延伸至心外膜的纤维组织带侵入，没有明显的中央通道。三色染色标本显示，通道被胶原纤维、脂肪组织以及众多发育良好的毛细血管或血窦所取代，其中发现大量红细胞。
我们得出结论，激光TMR对急性心肌缺血无帮助，但在术后第60天时可导致通道内新生血管形成。激光TMR诱导的血管生成可能在缓解慢性缺血中发挥作用。
