title: Experimental investigations on relationships between myocardial damage and laser type used in transmyocardial laser revascularization (TMLR).
abstract: Transmyocardial laser revascularization (TMLR) using a CO2 laser is clinically attempted in end-stage ischemic heart disease that is not treated by conventional bypass grafting or transluminal angioplasty. Besides, clinical trials of TMLR using a Ho:YAG laser have started recently. In this study, we compared the degree of damage to normal myocardium using these 2 types of lasers. Hearts of adult mongrel dogs were exposed under general anesthesia. Dogs were divided into 2 groups; those with channels made in the left ventricle by CO2 laser (CO2 group, n = 5) and those with channels made by Ho:YAG laser (Ho:YAG group, n = 5). The chest was temporarily closed, then serum MB isozyme of creatinine kinase (CK-MB) and troponin T (TnT) were measured sequentially. Twenty-four hours after laser irradiation, hearts were isolated for pathological studies with hematoxylin-eosin and Masson's trichrome stains. The CO2 group produced CK-MB with a peak of 1162.2 +/- 462.2 IU/l and the Ho:YAG group 1804.0 +/- 992.4 IU/l after 12 hours, and there was a significant difference between two groups (p < 0.01). The CO2 group produced TnT with a peak of 1.2 +/- 0.4 ng/ml and the Ho:YAG group 11.6 +/- 4.1 ng/ml after 6 hours, and the peak value in Ho:YAG group was significantly higher than that in the CO2 group (p < 0.001). Thirty channels were confirmed histologically in the CO2 group, and the width of thermal damage layer around the channel lumen was 249 +/- 83 microns. Twenty-seven channels were confirmed histologically in the Ho:YAG group, and the width of thermal damage layer was 760 +/- 288 microns. Thermal damage in the Ho:YAG group was significant greater than that in the CO2 group (p < 0.01). We concluded that TMLR using a CO2 laser is more suitable for end-stage myocardial ischemia than a Ho:YAG laser in terms of myocardial damage.
authors.affiliation: Department of Surgery, Kobe University School of Medicine.
authors.forename: T
authors.initials: T
authors.lastname: Kitade
authors.forename: M
authors.initials: M
authors.lastname: Okada
authors.forename: Y
authors.initials: Y
authors.lastname: Tsuji
authors.forename: M
authors.initials: M
authors.lastname: Nakamura
authors.forename: Y
authors.initials: Y
authors.lastname: Matoba
mesh_terms: D000535:Aluminum; D000818:Animals; D002245:Carbon Dioxide; D003402:Creatine Kinase / Q000097:blood; D004285:Dogs; D006695:Holmium; D007527:Isoenzymes; D007700:Kinetics; D053685:Laser Therapy / Q000379:methods*; D017202:Myocardial Ischemia / Q000473:pathology / Q000601:surgery*; D009204:Myocardial Revascularization / Q000379:methods*; D009206:Myocardium / Q000473:pathology; D020107:Troponin T / Q000097:blood; D015019:Yttrium
chemical_list: D007527:Isoenzymes; D020107:Troponin T; D002245:Carbon Dioxide; D015019:Yttrium; D000535:Aluminum; D003402:Creatine Kinase; D006695:Holmium