Mechanism of neoangiogenesis development after transmyocardial laser revascularization

摘要

Abstract: Pathophysiological mechanisms of transmyocardial laser revascularization (TLMR) remain insufficiently clear. Since the laser transmyocardial channels soon after their formation are closed and then substituted by the connective tissue, the laser effect is caused by neoangiogenesis in the place of injury. We have carried out TLMR in 250 Vistar rats with the help of Nd:YAG laser. In the point of lesion the development of inflammatory process with feebly marked, exudation reaction was registered. A connective tissue scar have been forming in the place of the lasers channel. The substantial growth of small vessels number is shown morphometrically in this place. The number of mast cells in have been increasing since the first hours after operation. The most part of the mast cells were degranulated, that indicates the release of bioactive substances into the extracellular space. The signs of activation of fibroblasts in the place of myocardium damage (abrupt hyperplasia of granular endoplasm reticulum on the electron microphotographs) were evident by the 5 - 6 day. At the first hours and days the platelets in the laser damaged vessels aggregated and the number of $alpha granules decreased. It also points at the presence of bioactive substances, secreted by platelets. Zymography showed, that the activity of collagenase have been sharply increasing, with its peak on the 10 day after operation. Thus, the activation of noncontracting elements of myocardium during TMR may be the source of growth factors and proteases necessary for neoangiogenesis. !24