The Evaluation of Transmyocardial Laser Revascularization with the aid of PET

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(Method) Adult beagle dogs were anesthesized and ventilated mechanically with room air. A left thoracotomy was performed and a heart was exposed. Then the regional myocardial blood flow (RMBF) by the positron emmision tomography (PET) with ^<13>NH^3 was measured. Then the left anterior descending coronary artery was ligated just distal to the first diagonal branch and acute myocardial infarction was made. Then post-MI RMBF was measured by PET.The dogs were divided into two group ; control group and TMLR group. In the control group, thoracotomy was closed, And in the TMLR group, the transmural channels were created in the LAD territory by a CO2 laser. The channels in diameter about 1mm were made with a density of 1 channel / cm2, an average of 10 channels. Then RMBF was measured by PET, too. And the thoracotomy was closed. RMBF was measured two weeks and two monthes after the operation. Then the dogs were sucrificed and the hearts were excised. The tissue level of matrix metalloproteina … More se (MMP) and platelet-derived endothelial cell growth factor (PDECGF) was measured by the zymography and spectrophotometer. In additioon, the endothelial cells were stained by double immunohistochemical technique with antiPCNA antibody and anti-Factor VIII-related antibody, and then the microvessel density was evaluated. (Results) The rate of the absorbed level of 13NH3 in the infarcted territory to non-infarcted area was caluculated, and the value was evaluated as the percentage of the pre-infarcted one. In the control group, the value of post-infarction, 2 weeks and 2 monthes after operation were 25%, 62% and 49%. In the TMLR group, the value of post-infarction, post-TMLR, 2 weeks and 2monthes were 36%, 29%, 73% and 67%. There was no significant difference between the two groups, and TMLR did not increase regional blood flow in acute ischemic myocardium. Any completely patent channels were not found, and they were infiltrated with granulation tissue. A large amount of microvessels and proliferating endothelial cells were found around the channels. The level of MMP-2, MMP-9 and PDECGF increased in the infarcted territory. They are significantly higher in the TMLR group than in the control group. The microvessel dencity was significantly higher in the TMLR group than in the control group. (Conclusion) TMLR did not increased RMBF in the acute ischemic myocardium. Thecompletely patent channels were not found, and they were infiltrated with granulation tissue. TMLR could stimulate the angiogenesis with the expression of MMP and PDECGF. Less