Analysis of the new indirect revascularization method by determining objective parameters of clinical chemistry, histo-chemistry and histology

Objective: This experimental study was initiated to determine whether trans myocardial laser revascularization (TMLR) after acute myocardial ischemia m ay improve clinical chemistry and diminish the amount of necrosis. In addit ion, 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 my ocardial ischemia (observation period 6 h): seven pigs served as controls ( thoracotomy only). An additional seven pigs had left anterior descending ar tery (LAD) occlusion only (ischemia group). A subsequent 14 pigs were treat ed by TMLR (CO2) prior to LAD occlusion: Seven pigs received one laser chan nel/cm(2) (group 1) and in seven pigs two channels/cm(2) in the LAD territo ry (group 2) were performed. In addition, 16 pigs underwent TMLR without is chemia: Eight pigs received one channel/cm(2) (group 3) and eight pigs two channels/cm(2) (group 4). Clinical chemistry, histo-chemical assessment and histology were performed. Results: TMLR limits the expansion of the myocar dial 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 gr oups 3 and 4 compared with control did not differ significantly (P = ns). P reventive creation of microchannels before ischemia did not diminish ischem ic 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 o f the experiment, except higher values of laser group 2 (P < 0.05). Laser g roups 3 and 4 revealed significantly higher MWC values compared with contro l (P < 0.001). Conclusions: This prolonged acute study demonstrates that CO 2-TMLR significantly reduces the amount of necrosis in the area at risk, bu t does not reduce cardiac ischemic markers. In healthy myocardium, TMLR sig nificantly increases myocardial water content and ischemic parameters and i nduces small ischemic and very small necrotic areas surrounding open laser channels. Generally, the elevated cardiac enzymes and proteins are mainly a ttributed to the expected rise caused by vaporization of myocardial tissue in all laser groups. (C) 1999 Elsevier Science B.V. All rights reserved.