摘要：
目的·评估超声形成的声学力能否减少心脏手术后进入脑血管的微栓.方法·实验用小型猪7头,3头猪用于注射气体微栓,3头猪用于注射固体微栓,另1头猪用于检测超声能量对于组织有无损伤.常规麻醉后游离并暴露右颈总动脉、左心耳、升主动脉和近端无名动脉.于左心耳插入一根冷灌针头,用于注射气体微栓或固体微栓.将制作好的水囊超声探头置于升主动脉与无名动脉分叉处.另一超声探头置于右颈总动脉用于检测微拴.分别于关闭和开启超声能量后注射微栓混悬液10 mL(气体或固体),各重复3次,观察超声屏蔽前后通过右颈总动脉的微栓变化.对造影动态图像进行时间-强度曲线分析.另取1头猪,将水囊超声探头置于升主动脉与无名动脉分叉处,用同等强度的超声能量辐射5 min,之后分别于超声照射部位及非照射部位取少量主动脉、气管、食管组织,行苏木精-伊红染色(H-E染色).结果·超声结果表明,在超声能量辐射后注射微栓,右颈总动脉内关注区的超声均值强度较未经超声能量辐射注射微栓时显著下降.其中气体微栓的超声均值强度由未经辐射的128.8±32.7降至辐射后的56.4±21.1(P=0.000);固体微栓的超声均值强度由未经辐射的109.8±19.9降至辐射后的75.4±21.9(P=0.000).超声辐射部位与非超声辐射部位的主动脉、气管、食管的组织结构无明显差异.结论·采用超声辐射能够有效屏蔽术中产生的微栓,减少随血流进入脑血管的微栓数目,可能有助于降低心脏外科手术后神经系统并发症的发生.%Objective·To evaluate if ultrasound acoustic force can reduce cerebrovascular micro-emboli after cardiac surgery. Methods·Seven pigs were used during the experiment, three for air emboli injection, three for solid emboli injection, and one for safety study. After anesthesia, right carotid artery, left atrial appendage, ascending aorta, and proximal innominate artery were exposed surgically. An intravenous catheter was inserted into left atrial appendage for injecting air or solid micro-emboli. The ultrasound transducer was placed at the bifurcation of the aorta and the innominate artery, with the sonic beacon toward the descending aorta. Micro-emboli through the right carotid artery were monitored by ultrasound transducer. Micro-emboli mixture (10 mL, air emboli or solid emboli) was injected with or without ultrasonic activation, each repeating three times. Micro-emboli through right carotid artery were measured under each condition. Ultrasonic time-intensity curves were performed and analyzed. For safety test, ultrasound with the same energy on a pig for 5 minutes was applied. The tissue samples were obtained for pathological evaluation from sonicated and non-sonicated areas of the aorta, trachea and the esophagus. Results·Ultrasonic time-intensity curve showed that the mean ultrasonic intensity of the right common carotid artery significantly decreased after ultrasonic activation. The intensity of air emboli reduced from 128.8±32.7 to 56.4±21.1 (P=0.000), while the intensity of solid emboli reduced from 109.8±19.9 to 75.4±21.9 (P=0.000). H-E staining of the surrounding tissues showed no differences between sonicated and non-sonicated areas of the aorta, trachea and the esophagus. Conclusion·Ultrasonic acoustic force can decrease the number of micro-emboli that enter the brain. Thus, it may lower the risk of postoperative neurological complications after cardiac surgery.
