title: Analysis of the new indirect revascularization method by determining objective parameters of clinical chemistry, histo-chemistry and histology.
abstract: OBJECTIVE
  This experimental study was initiated to determine whether transmyocardial laser revascularization (TMLR) after acute myocardial ischemia may improve clinical chemistry and diminish the amount of necrosis. In addition, the influence of TMLR on healthy myocardium was analyzed.
  
  
  METHODS
  The prolonged short-term effectiveness of TMLR was evaluated in 44 open-chest anesthetized pigs with (n = 21) or without (n = 23) the setting of acute myocardial ischemia (observation period 6 h): seven pigs served as controls (thoracotomy only). An additional seven pigs had left anterior descending artery (LAD) occlusion only (ischemia group). A subsequent 14 pigs were treated by TMLR (CO2) prior to LAD occlusion: Seven pigs received one laser channel/cm2 (group 1) and in seven pigs two channels/cm2 in the LAD territory (group 2) were performed. In addition, 16 pigs underwent TMLR without ischemia: Eight pigs received one channel/cm2 (group 3) and eight pigs two channels/cm2 (group 4). Clinical chemistry, histo-chemical assessment and histology were performed.
  
  
  RESULTS
  TMLR limits the expansion of the myocardial infarction zone: laser group 2 indicated a significant smaller area of necrosis in the area at risk (ischemic group (31%) vs. laser group 1 (19%), P = ns; laser group 2 (7%) vs. ischemic group, P < 0.01; laser group 1 vs. 2, P < 0.01). The amount of the area of necrosis and ischemia of laser groups 3 and 4 compared with control did not differ significantly (P = ns). Preventive creation of microchannels before ischemia did not diminish ischemic parameters (P = ns). The myocardial water content-measurements (MWC) in the ischemia, laser 1 and 2 groups did not show any difference at the end of the experiment, except higher values of laser group 2 (P < 0.05). Laser groups 3 and 4 revealed significantly higher MWC values compared with control (P < 0.001).
  
  
  CONCLUSIONS
  This prolonged acute study demonstrates that CO2-TMLR significantly reduces the amount of necrosis in the area at risk, but does not reduce cardiac ischemic markers. In healthy myocardium, TMLR significantly increases myocardial water content and ischemic parameters and induces small ischemic and very small necrotic areas surrounding open laser channels. Generally, the elevated cardiac enzymes and proteins are mainly attributed to the expected rise caused by vaporization of myocardial tissue in all laser groups.
authors.affiliation: Division of Cardiovascular Surgery, Albert-Ludwigs-University Freiburg, School of Medicine, Germany. lutter@ch11.ukl.uni-freiberg.de
authors.forename: G
authors.initials: G
authors.lastname: Lutter
authors.forename: J
authors.initials: J
authors.lastname: Martin
authors.forename: W
authors.initials: W
authors.lastname: Köster
authors.forename: A B
authors.initials: AB
authors.lastname: Grawitz
authors.forename: P
authors.initials: P
authors.lastname: Esenwein
authors.forename: A
authors.initials: A
authors.lastname: Geiger
authors.forename: B
authors.initials: B
authors.lastname: von Specht
authors.forename: F
authors.initials: F
authors.lastname: Beyersdorf
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D001834:Body Water; D003402:Creatine Kinase / Q000097:blood; D004195:Disease Models, Animal; D005069:Evaluation Studies as Topic; D007150:Immunohistochemistry; D007770:L-Lactate Dehydrogenase / Q000097:blood; D053685:Laser Therapy / Q000379:methods*; D017202:Myocardial Ischemia / Q000601:surgery*; D009204:Myocardial Revascularization / Q000379:methods*; D009206:Myocardium / Q000737:chemistry* / Q000473:pathology*; D009211:Myoglobin / Q000097:blood; D012016:Reference Values; D015996:Survival Rate; D013552:Swine; D016896:Treatment Outcome
chemical_list: D009211:Myoglobin; D007770:L-Lactate Dehydrogenase; D003402:Creatine Kinase