Comparative Experiments On Holmium Laser To True-cut Biopsy Needle Myocardial Revascularization Series Study

There are many conflicting results obtained concerning the mechanism and result of transmyocardial revasculanzation (TMR). Our series of experiments were designed to study the mechanism and efficacy of blood perfusion to ischemic myocardium via the transmyocardial channels created by either Ho-Yag laser or True-cut biopsy needle with myocardial contrast echocardiography (MCE) using a new generation of contrast and second harmonic imaging acutely. The chronic results were evaluated with MCE in conjunction with histological method.In the research of Ho-Yag laser TMR, we partially ligated the left anterior descending coronary artery between the second and third diagonal branch of nine canine hearts to produce an ischemia region in the anterior wall of left ventricle. Then TMR were performed in this region with channel density of ~2/cm~2. MCE were performed on the short-axis view of this region before ischemia, when ischemia and after laser TMR. The last MCE were performed one month later and after which the hearts were prepared for histologic examination.Acoustic density of microbubble by MCE in the experiment region patently decreased when ischemia than that before, it increased remarkably after laser TMR than that when ischemia and up nearly to that of before ischemia and that of non-ischemic control region (lateral wall ). We found a phenomenon that acoustic density of microbubbles in the TMR region elevated ahead which of control region. The chronic result of MCE (one month later), the acoustic density of microbubble on the same view remained higher than that when acute ischemia, but was lower than that of either before ischemia or acutely after TMR. The acoustic density of microbubble in either TMR or control region elevated at almost the same time and the beginning part of their value curves were overlaped. The histologic features were that no evidence of channel patency were found in this group, and in the tract of laser channels, the density of vasculatures including arterioles, capillaries and...