心肌再血管化机制的对比实验研究

目的观察研究钬激光和True-cut活检针心肌再血管化近、远期的机制和效果。方法利用经静脉注射造影剂对犬缺血心肌模型进行心肌超声微泡造影。结果部分结扎犬的冠状动脉前降支,建立缺血模型后,缺血区超声微泡密度明显降低,分别用2种方法再血管化后,2组犬缺血区超声微泡密度较缺血时均明显增加,接近其缺血前的微泡密度;再血管化区超声微泡较其他部位提前显影。远期超声微泡检查显示心肌灌注较急性缺血时也有一定改善。结合组织学方法发现,远期心肌灌注的改善得益于隧道周围新生循环结构如心肌窦和新生血管的增加。结论钬激光和True-cut活检针隧道均可即刻使缺血心肌灌注改善,并逐渐闭塞,新生循环结构使缺血区得到有限的灌注。应用新一代经静脉注射造影剂超声心肌微泡造影结合组织学方法可作为研究心肌再血管化机制的可靠手段。

A Comparative Study on the Mechanism of Transmyocardial Revascularization with True-cut Biopsy Needle and Laser

Objective To study the mechanism and effects of blood perfusion to the acute ischemic region of myocardium through channels created by Ho-Yag laser and True-cut biopsy needles with myocardial contrast echocardiography. Methods We partially ligated the left anterior descending coronary artery of canine hearts between 1st and 2nd diagonal branches to produce two groups acute myocardial ischemia models and then performed transmyocardial revascularization on this region with Ho-Yag laser and True-cut biopsy needles respectively.We performed myocardial contrast echocardiography with a new generation of ultrasound contrast agent and second harmonic imaging of this region before,when ischemia and after laser revascularization before we took another and histological exam one month later.Pictures were taken with R wave trigger skill.Results Acoustic density(dB) in the ischemia region(Anterior wall) with MCE decreased obviously after the LAD was ligated(Laser group: 5.40±1.81,Needle group: 7.11±2.51.P<0.01) than that before(Laser group: 11.69±1.61,Needle group: 12.96±2.88).It increased remarkably after TMR by either laser or True cut biopsy needle(Laser group: 11.02±2.01,Needle group: 10.01±4.45.P<0.01) than that when ischemia and approximated to that before ischemia(P>0.05).It was still higher than that of ischemia after one month(Laser group: 8.37±0.86,Needle group: 10.87±1.25) we found that the acoustic density of the contrast developed one picture(one cardiac cycle) ahead in the TMR region than that in the lateral and other region of the LV wall in the scan of both groups.No channel was found open with microscope after one month and there were angio-genisis of sinosoid and vessel-like structures around the channels created by both laser and biopsy needle.Conclusion Acute ischemic myocardium can be perfused by oxygenated blood from left ventricle through channels created with both Ho-Yag laser and True-cut biopsy needles;Evidence of blood perfusion through these channels mainly during systolic phase was detected.The perfusion to the ischemia region was performed by the angiogenisis within and around the channels after one month.Myocardial contrast ultrasound using intravenous perfluorocarbon-exposed sonicated dextrose albumin canbe regarded as a reliable method in the study of transmyocardial revascularization.