Objective. To study the mechanism and effects of blood perfusion to the acute ischemic region of myocardium through Ho-YAG laser channels with myocardial contrast echocardiography. Methods. To produce the model of acute myocardial ischemia, we partially ligated the left anterior decending (LAD)coronary artery of canine hearts between lst. and 2nd. diagonal branches and then performed transmyocardial revascularization in this region with Ho- YAG laser. Myocardial contrast echocardiography was made with a new generation of ultrasound contrast agent and second harmonic imaging of this region before, after ischemia and after laser revascularization. Pictures were taken with “R” wave trigger skill.Results. Acoustic density derterming in the ischemia region (anterior wall)with MCE (myocardial contrast echocardiography )was obviously decreased( 5.40 ± 1.81) after the LAD was ligated, as compared with before( 11.69 ±1.61, P ＜ 0.01 ). It was increased remarkably after transmyocardial laser revascularizatuon (TMLR) ( 11.2 ± 2.01, P＜ 0. 01 )as compared with that when ischemia and approximated to that before ischemia(P ＞ 0.05). There were no differences in acoustic density in the lateral wall(as control)among these comprehensive three periods(P ＞ 0.05). Contrast in the laser region developed one cardiac cycle ahead of that in the non-ischemic normal region.Conclusion. Acute ischemic myocardium can be peffused by oxygenated blood from the left ventricle through HoYAG laser channels. Evidence of blood perfusion through laser channels during systolic phase was detected, and myocardial contrast ultrasonography using intravenous perfluorocarbon-exposed sonicated dextrose albumin may be regarded as a reliable method in the study of transmyocardial revascularization.

脉冲掺钕钇铝石榴石激光对增生性瘢痕成纤维细胞胶原合成的影响

Objective In order to explore the selectively inhibitory effects of pulsed Nd:YAG laser irradiation on collagen production of scar fibroblasts in vitro.Methods Cultured fibroblasts derived from hypertrophic scars(HS) and normal human skin were irradiated with a pulsed Nd:YAG laser(wavelength 1 064 nm,pulse width 150 μ s) at various energy density levels (500,1 000,1 500 and 2 000 J/cm2).At 24 hours after laser irradiation, collagen production of fibroblasts was measured by the incorporation of 3H proline. The expression of proα 1(I)procollagen mRNA was investigated by blot hybridization techniques. Results Collagen production of HS fibroblasts was significantly increased, as 2 times as that of normal skin fibroblasts. Type I procollagen mRNA level in HS fibroblasts was markedly elevated, as 3 times as that in normal skin fibroblasts.Conclusion Pulsed Nd:YAG laser at energy density of 1 000 J/cm2 can selectively suppress collagen synthesis and type I procollagen mRNA level of HS fibroblasts.