Transmyocardial revascularization on canine with Ho:YAG laser: an experimental study

Background and Objective: To evaluate the efficiency of transmyocardial revascularization with Ho:YAG laser and find out adequate physical parameters of the laser. Materials and Methods: 10 dogs were studied. All the samples were divided into two groups: the laser group (5 dogs) and the control group (5 dogs). Acute myocardial ischemia was induced in all the samples, and transmyocardial laser revascularization (TMLR) was only done in the laser group. We compared the difference of improvement in myocardial perfusion between the two groups with single photon emission computed tomograph (SPECT) and observed the patency of the laser channels and heat injures in the tissue adjacent to the channels with light- and electro-scope. Results: After 4 weeks, the recovery of myocardial perfusion was significantly faster in the laser group than in the control group through SPECT (P<0.05). Most of the laser channels drilled with Ho:YAG laser were filled with fibrin. There were amount of microvessels and erythrocytes inside and around the channels. Only slight heat injures were seen in the tissue adjacent to the channels. Only 20-30 watts were needed in TMLR. Conclusions: Transmyocardial revascularization with Ho:YAG laser limits infarct expansion and reduces myocardial ischemia efficiently. TMLR with Ho:YAG laser can become a new technique to treat ischemic heart disease.