Guerrieri Wolf Lorenzo, Choudhary Bikram P, Abu-Omar Yasir, Taggart David P
Department of Cardiothoracic Surgery, John Radcliffe Hospital, Oxford, United Kingdom.
J Thorac Cardiovasc Surg. 2008 Mar;135(3):512-20. doi: 10.1016/j.jtcvs.2007.07.062.
Cerebral microembolization is a well-recognized phenomenon after cardiac valve replacement, but the relative proportion of solid and gaseous emboli is uncertain. Particulate microemboli are thought to be the most damaging. With the use of multifrequency transcranial Doppler ultrasound, we compared the number and nature of microemboli in recipients of biologic and mechanical aortic valve prostheses.
The middle cerebral arteries of 60 patients were monitored bilaterally with a new-generation transcranial Doppler ultrasound (Embo-Dop, DWL Elektronische Systeme GmbH, Singen, Germany) that rejects artefacts online and automatically discriminates between solid and gaseous microemboli. All recordings were performed during a 30-minute period 1 day before and at a mean of 5 days and 3 months after isolated aortic valve replacement with a biologic (30, group B) or mechanical (30, group M) prosthesis.
The patients in group B were older, with a mean age of 70.6 +/- 9.7 years versus 55.4 +/- 9.4 years (P < .005) in the patients in group M. Biologic prosthesis recipients were all taking aspirin (no warfarin); patients with mechanical valves were well anticoagulated with warfarin both 5 days and 3 months after surgery. None of the patients had solid microemboli preoperatively. Five days postoperatively, the absolute number of cerebral microemboli was 145 and 594 for total microemboli (P = .001) and 41 and 182 for solid microemboli (P = .002) in groups B and M, respectively. At 3 months, the absolute number was 65 and 608 for total microemboli (P < .001) and 10 and 188 for solid microemboli (P < .001) in groups B and M, respectively. Solid microemboli accounted for 16% of the total microembolic load in group B compared with 31% in group M (P = .05) at 3 months.
Solid cerebral microemboli represent approximately one third of the total cerebral microembolic load after mechanical aortic valve replacement and are detectable in the majority of such patients both 5 days and 3 months after surgery. The neurofunctional consequences of this phenomenon should be carefully assessed.
脑微栓塞是心脏瓣膜置换术后一种公认的现象，但固体栓子和气态栓子的相对比例尚不确定。颗粒性微栓子被认为最具破坏性。我们使用多频经颅多普勒超声，比较了生物主动脉瓣假体和机械主动脉瓣假体接受者脑微栓子的数量和性质。
对60例患者的双侧大脑中动脉进行监测，使用新一代经颅多普勒超声（Embo-Dop，德国辛根DWL电子系统有限公司），该设备可在线排除伪像，并自动区分固体和气态微栓子。所有记录均在孤立主动脉瓣置换术前1天、术后平均5天和3个月的30分钟内进行，置换的假体为生物瓣（30例，B组）或机械瓣（30例，M组）。
B组患者年龄较大，平均年龄为70.6±9.7岁，而M组患者为55.4±9.4岁（P<0.005）。生物瓣假体接受者均服用阿司匹林（未服用华法林）；机械瓣患者在术后5天和3个月均用华法林充分抗凝。所有患者术前均未出现固体微栓子。术后5天，B组和M组脑微栓子总数分别为145个和594个（P = 0.001），固体微栓子分别为41个和182个（P = 0.002）。3个月时，B组和M组脑微栓子总数分别为65个和608个（P<0.001），固体微栓子分别为10个和188个（P<0.001）。3个月时，B组固体微栓子占总微栓负荷的16%，而M组为31%（P = 0.05）。
固体脑微栓子约占机械主动脉瓣置换术后总脑微栓负荷的三分之一，且在术后5天和3个月的大多数此类患者中均可检测到。应仔细评估这一现象对神经功能的影响。
