Microperfusion enhancement after TMLR in chronically ischemic porcine hearts

Objective. The purpose of this study was to determine the effect of transmy ocardial laser revascularization (TMLR) on myocardial perfusion and functio n in chronically ischemic myocardium. Methods. In the first operation a stenosis of the left anterior descending artery was created in 20 open-chest anesthetized pigs to implement this isc hemic model. In contrast, four pigs served as controls (thoracotomy only). Seven days later (2nd operation), all animals were stud led at baseline by analyzing different parameters of perfusion (radioactive microspheres), fun ction, and intramyocardial pressure. Afterwards, pigs who received a left a nterior descending artery stenosis were randomized into one of three groups : animals in laser group 1 (n = 7) received one and in laser group 2 (n = 7 ) two laser channels per cm(2) in the left anterior descending artery terri tory, Animals of the ischemic group (n = 6) underwent the same procedures w ithout transmyocardial laser revascularization. Three months later, the ani mals were re-studied (3rd operation) and additional analysis of histochemis try and myocardial water content was performed. Results. Regional myocardial blood flow (RMBF) in laser group 2 revealed st atistically higher RMBF values compared to the ischemic group (0.39+/-0.13 versus 0.14+/-0.12 ml/min/g: P = 0.043). after 3 months, whereas the absolu te RMBF had not increased compared to the 1-week baseline values. Left vent ricular stroke work index (LVSWI) at rest and under stress did not show any improvement compared to the initial values in all study groups (P = ns). N evertheless, laser group 1 demonstrated relatively higher LVSWImax values c ompared to the ischemic (1.33+/-0.19 versus 0.93+/-0.16 mJ/kg: P = 0.03) an d laser group 2 (1.33+/-0.19 versus 1.02+/-0.15; P = 0.024). Regional contr actility of Laser groups 1 and 2 recovered after 3 months (which had deteri orated shortly after transmyocardial laser revascularization) and increased under stress (100% versus 144.33+/-46.42. P=0.029 and 100% versus 116.26+/ -21.06. P = 0.034; respectively). In contrast, the corresponding ischemic g roup values were not different from intial values (P = ns). Conclusions. This model of chronic regional ischemia demonstrates that CO2- laser revascularization significantly improves microperfusion and regional function, whereas the overall perfusion and global LV function is unchanged . (C) 2001 The International Society for Cardiovascular Surgery. Published by Elsevier Science Ltd. All rights reserved.