Interventional Radiology Laboratory, Department of Radiology and Biomedical Imaging, University of California San Francisco, 185 Berry Street, Suite 350, Room 320, San Francisco, CA 94107-5705, USA.
Int J Cardiovasc Imaging. 2013 Jan;29(1):159-68. doi: 10.1007/s10554-012-0076-7. Epub 2012 Oct 13.
To quantify, using MRI, the acute impacts of defined volume and sizes of coronary microemboli on myocardial viability and left ventricular (LV) function and to use LAD occlusion/reperfusion, as a reference. A total of 28 farm pigs were used in this study. Eight animals were used as controls. Successful coronary interventions were performed under X-ray fluoroscopy in 16 pigs to induce microinfarct (delivery of 16 mm(3) of 40-120 μm) and large infarct (90 min LAD occlusion/reperfusion). On day 3, animals were imaged using contrast enhanced (in beating and non-beating hearts) and cine MRI for evaluating LV viability and function, respectively. Microscopy and cardiac injury enzymes were used to confirm the presence of necrosis. Myocardial damage was smaller after microembolization than occlusion/reperfusion (6.5 ± 0.6%LV mass vs. 12.6 ± 1.2%, P < 0.001). The increase in LV end-systolic volume and decreases in ejection fraction, cardiac output and regional systolic wall thickening, however, were comparable between groups, but significantly differed from controls. MRI also demonstrated microvascular obstruction after microembolization and occlusion/reperfusion as hyperenhanced and hypoenhanced regions, respectively. Microscopic examination revealed patchy necrosis, inflammatory cell infiltration, but no intramyocardial hemorrhage after microembolization and extensive intramyocardial hemorrhage and transmural damage in the occlusion/reperfusion group. Cardiac injury enzymes confirmed presence of myocardial damage in animals with interventions. Coronary microemboli have acute impact on LV function compared to control animals. Despite the difference in myocardial damage, global and regional LV dysfunction after microembolization was comparable to occlusion/reperfusion. This MR study suggests that the pattern of myocardial damage plays a role in LV dysfunction.
使用 MRI 定量评估冠状动脉微栓塞的体积和大小对心肌存活和左心室（LV）功能的急性影响，并采用左前降支（LAD）闭塞/再灌注作为参考。本研究共使用了 28 头农场猪。其中 8 头作为对照组。在 16 头猪的 X 射线透视下成功进行了冠状动脉介入治疗，以诱发微梗死（输送 16mm³ 大小为 40-120μm 的微栓子）和大梗死（90 分钟 LAD 闭塞/再灌注）。第 3 天，使用对比增强（跳动和非跳动心脏）和电影 MRI 对动物进行成像，分别评估 LV 存活和功能。显微镜检查和心脏损伤酶用于确认坏死的存在。微栓塞后的心肌损伤比闭塞/再灌注小（6.5±0.6%LV 质量 vs. 12.6±1.2%，P<0.001）。然而，LV 收缩末期容积增加和射血分数、心输出量和局部收缩壁增厚减少在两组之间是可比的，但与对照组有显著差异。MRI 还显示微栓塞和闭塞/再灌注后存在微血管阻塞，分别为高增强和低增强区域。显微镜检查显示微栓塞后出现斑片状坏死、炎症细胞浸润，但无心肌内出血，而闭塞/再灌注组则出现广泛的心肌内出血和透壁损伤。心脏损伤酶证实干预动物存在心肌损伤。与对照动物相比，冠状动脉微栓塞对 LV 功能有急性影响。尽管心肌损伤程度不同，但微栓塞后 LV 整体和局部功能障碍与闭塞/再灌注相似。这项磁共振研究表明，心肌损伤模式在 LV 功能障碍中起作用。
