Guerrieri Wolf Lorenzo, Abu-Omar Yasir, Choudhary Bikram P, Pigott David, Taggart David P
Department of Cardiothoracic Surgery, John Radcliffe Hospital, Oxford, United Kingdom.
J Thorac Cardiovasc Surg. 2007 Feb;133(2):485-93. doi: 10.1016/j.jtcvs.2006.10.002.
Intraoperative cerebral microembolism is a cause of cerebral dysfunction after cardiac surgery, and particulate microemboli are the most damaging. Using a new-generation transcranial Doppler ultrasound, we compared the number and nature of microemboli in patients undergoing off-pump coronary artery bypass grafting during performance of proximal anastomoses with three techniques: an aortic side-biting clamp and two clampless devices (the Enclose II device [Novare Surgical Systems, Inc, Cupertino, Calif] and the Heartstring II device [Guidant Corporation, Santa Clara, Calif]) developed to obviate the need for an aortic side-biting clamp, thereby reducing the number of cerebral microemboli.
Bilateral continuous monitoring of the middle cerebral arteries was performed with a multirange, multifrequency transcranial Doppler device that both automatically rejects artifacts online and discriminates between solid and gaseous microemboli. Recordings were continuously undertaken during performance of 66 proximal aortic anastomoses in 42 patients. Thirty-five anastomoses were performed with an aortic side-biting clamp, 20 with the Enclose device, and 11 the Hearstring device.
Most microemboli occurred during application/insertion and removal of each device from the ascending aorta. The median number (interquartile range) of total microemboli was 11 (6-32) during side clamping, 11 (6-15) with the Enclose device, 40 (31-48) with the Heartstring device (P < .01). The proportion of solid microemboli was significantly higher in the side-clamp group (23%) compared with 6% and 1% in the Enclose and Heartstring groups, respectively (P < .01).
Avoidance of aortic side clamping results in a significant reduction in the proportion of solid microemboli detected with transcranial Doppler. As solid microemboli are probably the most damaging, use of the Enclose and Heartstring devices may represent an important strategy for minimizing cerebral injury during proximal aortic anastomoses.
术中脑微栓塞是心脏手术后脑功能障碍的一个原因，而颗粒性微栓子的损害最大。我们使用新一代经颅多普勒超声，比较了在非体外循环冠状动脉搭桥手术患者进行近端吻合时，采用三种技术（一种主动脉侧壁钳夹术和两种无需主动脉侧壁钳夹的无钳夹装置，即Enclose II装置[诺瓦雷外科系统公司，加利福尼亚州库比蒂诺]和Heartstring II装置[Guidant公司，加利福尼亚州圣克拉拉]）时微栓子的数量和性质，以减少脑微栓子的数量。
使用多量程、多频率经颅多普勒装置对双侧大脑中动脉进行连续监测，该装置可在线自动排除伪差，并区分固体和气体微栓子。在42例患者进行66次近端主动脉吻合过程中持续进行记录。35次吻合采用主动脉侧壁钳夹术，20次采用Enclose装置，11次采用Heartstring装置。
大多数微栓子出现在每种装置应用/插入升主动脉以及从升主动脉移除的过程中。侧壁钳夹时总微栓子的中位数（四分位间距）为11（6 - 32），使用Enclose装置时为11（6 - 15），使用Heartstring装置时为40（31 - 48）（P < 0.01）。侧壁钳夹组固体微栓子的比例显著高于Enclose组（6%）和Heartstring组（1%），分别为23%（P < 0.01）。
避免主动脉侧壁钳夹可使经颅多普勒检测到的固体微栓子比例显著降低。由于固体微栓子可能损害最大，使用Enclose和Heartstring装置可能是在近端主动脉吻合过程中使脑损伤最小化的一项重要策略。
