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（540±181） after the LAD was ligated

as compared with before（1169±161

P<001）.It was increased remarkably after transmyocardial laser revascularizatuon（TMLR）（112±201

P<001）as compared with that when ischemia and approximated to that before ischemia（P>005）.There were no differences in acoustic density in the lateral wall（as control）among these comprehensive three periods（P>005）.Contrast in the laser region developed one cardiac cycle ahead of that in the non-ischemic normal region. Conclusion.Acute ischemic myocardium can be perfused by oxygenated blood from the left ventricle through Ho-YAG 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 rnay be regarded as a reliable method in the study of transmyocardial revascularization.