【Abstract】 Objective: To observe the new vessel growth and the expression of vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (bFGF) after transmyocardial laser revascularization (TMR) and to investigate the relationship between TMR, growth factor and angiogenesis Methods: Eighty four Wistar rats underwent ligation of the left coronary artery They were randomly divided into two groups One ( n =42) served as controls, whereas the other ( n =42) underwent concomitant TMR by the creation of three transmural channels with modulating Nd: YAG laster on left ventricular free wall Then the animals were sacrificed at intervals of 3 days, 1, 2, 4, 6 and 8 weeks ( n =7 in each subgroup) HE staining was used to observe the vascular growth Immunohistochemistry using specific poly colonal antibodies was performed against VEGF and bFGF Growth factor expression was quantitated by comparing optical density (OD) of staining with computerized morphometric analysis Results: Mortality was similar in both groups TMR group showed capillary growth beginning at week 2 and thereafter gradually increased till week 8 TMR group had significant higher VEGF expression than controls in all subgroups with a peak at week 6 postoperatively (0 062±0 004 vs 0 198±0 022; p <0 001) No significant differences in bFGF expression were found between two groups at day 3 and week 1 It began to increase at week 2 in controls and reduced thereafter In TMR group, it peaked at week 6 Level of bFGF were significant higher in TMR group compared with the control group at week 6 and 8 (0 118±0 017 vs 0 233±0 012, p <0 001; 0 113±0 034 vs 0 162±0 010, p <0 001) Conclusion: The expression of VEGF and bFGF is significantly increased after TMR procedure with vascular growth beginning at week 2 in the model of acute myocardial ischemia in rats It appears that the angiogenic response is mediated by the release of certain angiogenic growth factors such as VEGF and bFGF With the increasing recognition that the long term patency of myocardial channels created by laser does not exist, its mechanism may be related to the effect of angiogenesis更多还原