BACKGROUND Therapeutic ultrasound (TUS) has been used to lyse infarct-related coronary artery thrombus. There has been no study examining the effect of TUS specifically on myocardial microthromboemboli seen in acute myocardial infarction and acute coronary syndromes. The aim of this study was to test the hypothesis that TUS improves myocardial blood flow (MBF) and reduces infarct size (IS) in this situation by dissolving myocardial microthrombi. METHODS An open-chest canine model of myocardial microthromboembolism was created by disrupting a thrombus in the left anterior descending coronary artery, and 1.05- and 0.25-MHz TUS (n = 7 each) delivered epicardially for 30 min was compared with control (n = 6). MBF and IS (as a percentage of left anterior descending coronary artery perfusion bed size) were measured 60 min after treatment. In addition, immunohistochemistry was performed to assess microthrombi, and histopathology was performed to define inflammation. RESULTS Transmural, epicardial, and endocardial myocardial blood volume and MBF (measured using myocardial contrast echocardiography) and percentage wall thickening were significantly higher 60 min after receiving TUS compared with control. The ratio of IS to left anterior descending coronary artery perfusion bed size was significantly smaller (P = .03) in the 1.05-MHz TUS group (0.14 ± 0.04) compared with the control (0.31 ± 0.06, P = .04) and 0.25-MHz (0.36 ± 0.08) groups. MBF versus percentage wall thickening exhibited a linear relation (r = 0.65) in the control and 1.05-MHz TUS groups but not in the 0.25-MHz TUS group (r = 0.29). The presence of myocardial microemboli in vessels >10 μm in diameter was significantly reduced in the 1.05-MHz TUS group compared with the other two groups. The distribution and intensity of inflammation was higher in the 0.25-MHz TUS group compared with the other groups. CONCLUSIONS TUS at 1.05 MHz is effective in restoring myocardial blood volume and MBF, thus reducing IS by clearing the microcirculation of microthrombi. IS reduction is not seen at 0.25 MHz, despite improvement in MBF, which may be related to the increased inflammation noted at this frequency. Because both acute myocardial infarction and acute coronary syndromes are associated with microthromboembolism, these results suggest that TUS could have a potential adjunctive role in the treatment of both conditions.

中文翻译：

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在冠状动脉微血栓栓塞症的犬模型中，治疗性超声波可改善心肌血流并减少梗塞面积。

背景技术治疗性超声波（TUS）已经用于溶解与梗塞相关的冠状动脉血栓。尚无研究检查TUS对急性心肌梗塞和急性冠状动脉综合征中见到的心肌微血栓栓塞的作用。这项研究的目的是检验在这种情况下TUS通过溶解心肌微血栓改善了心肌血流量（MBF）并减小了梗死面积（IS）的假设。方法通过破坏左前降支冠状动脉的血栓建立胸腔开放的犬心肌微血栓栓塞模型，并将心外膜分娩的1.05-和0.25-MHz TUS（每个n = 7）与对照组进行比较（n = 6）。治疗后60分钟测量MBF和IS（以左前降支冠状动脉灌注床大小的百分比）。此外，进行免疫组织化学以评估微血栓形成，并进行组织病理学以定义炎症。结果接受TUS后60分钟，与对照组相比，经壁，心外膜和心内膜心肌血容量和MBF（使用心肌对比超声心动图测量）和壁增厚百分比显着更高。在1.05-MHz TUS组中，IS与左前降支冠状动脉灌注床尺寸之比（P = .03）显着小于对照组（0.31±0.06，P = .04）和0.25（0.25 = 0.03） -MHz（0.36±0.08）组。MBF与壁增厚百分比在对照组和1.05 MHz TUS组中显示出线性关系（r = 0.65），而在0.25 MHz TUS组中则没有（r = 0.29）。血管中存在心肌微栓子> 与其他两组相比，1.05 MHz TUS组的直径10μm显着减小。0.25 MHz TUS组的炎症分布和强度高于其他组。结论TUS在1.05 MHz时可有效恢复心肌血容量和MBF，从而通过清除微血栓形成的微循环来降低IS。尽管MBF有所改善，但在0.25 MHz处并未观察到IS降低，这可能与在该频率下注意到的炎症增加有关。由于急性心肌梗塞和急性冠状动脉综合征均与微血栓栓塞症相关，因此这些结果表明，TUS在两种疾病的治疗中均具有潜在的辅助作用。0.25 MHz TUS组的炎症分布和强度高于其他组。结论TUS在1.05 MHz时可有效恢复心肌血容量和MBF，从而通过清除微血栓形成的微循环来降低IS。尽管MBF有所改善，但在0.25 MHz处并未观察到IS降低，这可能与在该频率下注意到的炎症增加有关。由于急性心肌梗塞和急性冠状动脉综合征均与微血栓栓塞症相关，因此这些结果表明，TUS在两种疾病的治疗中均具有潜在的辅助作用。0.25 MHz TUS组的炎症分布和强度高于其他组。结论TUS在1.05 MHz时可有效恢复心肌血容量和MBF，从而通过清除微血栓形成的微循环来降低IS。尽管MBF有所改善，但在0.25 MHz处并未观察到IS降低，这可能与在该频率下注意到的炎症增加有关。由于急性心肌梗塞和急性冠状动脉综合征均与微血栓栓塞症相关，因此这些结果表明，TUS在两种疾病的治疗中均具有潜在的辅助作用。尽管MBF有所改善，但在0.25 MHz处并未观察到IS降低，这可能与在该频率下注意到的炎症增加有关。由于急性心肌梗塞和急性冠状动脉综合征均与微血栓栓塞症相关，因此这些结果表明，TUS在两种疾病的治疗中均具有潜在的辅助作用。尽管MBF有所改善，但在0.25 MHz处并未观察到IS降低，这可能与在该频率下注意到的炎症增加有关。由于急性心肌梗塞和急性冠状动脉综合征均与微血栓栓塞症相关，因此这些结果表明，TUS在两种疾病的治疗中均具有潜在的辅助作用。