经颅多普勒监测评估疏血通对急性缺血性脑卒中患者颅内微栓子的干预作用

目的:通过经颅多普勒(TCD)自动监测微栓子信号(microembolicsignal,MES),研究疏血通注射液对急性缺血性脑卒中患者颅内微栓子的干预作用。方法:入院即时予德国DWL-Embo-dop型TCD监测MES,并对MES自动分析与计数,分为阳性、阴性两大组,两组再各随机分为常规治疗组、疏血通注射液治疗组,并分别于第2,5,7,10,15,20天监测TCD。结果:入院MES阳性组中,疏血通注射液治疗组20例,至第15天有19例MES消失,而对照组18例至第20天时仅有7例MES消失,两组MES消失的概率比较,差异有非常显著性意义(χ2=16.35,P<0.01);入院MES阴性组中,疏血通注射液治疗组至第20天有13例次出现MES,而对照组至第20天有32例次出现MES,两组MES出现的概率差异有显著性意义(χ2=13.08,P<0.05);疏血通注射液的抑栓作用在使用第5天即出现,于第7天达高峰,至第10,15天继续作用;但停药5d后有MES复现的现象。结论:疏血通注射液对急性缺血性脑卒中的微栓子具有预防和治疗作用;TCD栓子自动监测有助于及时发现微栓子、评估药物疗效。     

经颅多普勒监测评估疏血通对急性缺血性脑卒中患者颅内微栓子的干预作用

目的：通过经颅多普勒(TCD)自动监测微栓子信号(micro embolic signal，MES)，研究疏血通注射液对急性缺血性脑卒中患者颅内微栓子的干预作用。方法：入院即时予德国DWL-Embo-dop型TCD监测MES，并对MES自动分析与计数，分为阳性、阴性两大组，两组再各随机分为常规治疗组、疏血通注射液治疗组，并分别于第2，5，7，10，15，20天监测TCD。结果：入院MES阳性组中，疏血通注射液治疗组20例，至第15天有19例MES消失，而对照组18例至第20天时仅有7例MES消失。两组MES消失的概率比较，差异有非常显著性意义(x^2=16．35，P&;lt;0，01)；入院MES阴性组中，疏血通注射液治疗组至第20天有13例次出现MES，而对照组至第20天有32例次出现MES，两组MES出现的概率差异有显著性意义(x^2=13．08，P&;lt;0．05)；疏血通注射液的抑栓作用在使用第5天即出现，于第7天达高峰，至第10，15天继续作用；但停药5d后有MES复现的现象。结论：疏血通注射液对急性缺血性脑卒中的微栓子具有预防和治疗作用；TCD栓子自动监测有助于及时发现微栓子、评估药物疗效。     

缺血性卒中微栓子信号研究进展

TCD能探测循环中的微栓子信号(microembokic signal,MES)。MES是缺血性卒中急性期的常见现象，它的出现受探测时间、探测部位、卒中原发疾病、卒中类型、凝血功能和抗血小板聚集、抗凝及溶栓治疗等因素的影响。探测脑动脉MES对缺血性卒中高危人群筛选、病因学分析、早期诊断、疗效评价和预后判断等具有重要的临床实用价值。     

TCD监测阿斯匹林和海普宁对缺血性脑卒中微栓子信号的影响

目的：观察抗血小板聚集剂阿斯匹林（Aspirin)和抗凝药物低分子肝素钠海普宁（Hinparin)对缺血性脑卒中（Cerebral ischemic stroke,CIS)微栓子信号（Microembolic signals,MES)的影响。方法：应用经颅多普勒超声（TCD）检测仪对发病后72h内、未进行抗血小板和抗凝治疗的无出血性疾病且查血小板，凝血时间和凝血酶原时间正常的动脉源性CIS患行MES监测，将MES阳性随机分成三组：即Aspirin组、Hirparin组和对照组，分别给予Aspirin（100mgPoQd）＋常规治疗、Hirparin(2500IU ih Bid）＋常规治疗和常规治疗（丹参20ml加250ml液体中iv drop Qd）。10日后再次监测MES。结果：156例CIS首次监测，MES阳性46例，阳性率29．5％，治疗10日后再次监测，15例Aspirin组MES阳性8例，阳性率53．3％，15例Hirparin组MES阳性2例，阳性率13．3％，16例对照组MES阳性14例，阳性率87．5％，Aspirin组和Hirparin组MES阳性率均低于对照,且Hiraprin组低于Aspirin组。结论：对于新发近发生的动态源性CIS，口服Aspirin和皮下注射Hirparin治疗均能快速降低MES，它们是治疗CIS的有效方法，且Hirparin的作用优于Aspirin。     

无症状颈动脉狭窄患者脑血管栓子信号的超声研究

目的 应用经颅多普勒(TCD)观察无症状颈动脉狭窄患者脑血管微栓子信号(Mes)对缺血性脑卒中的预测价值.方法 颈动脉狭窄患者(颈动脉狭窄≥50%)22例,分别于人选当日、7d及6个月时对狭窄颈动脉同侧大脑中动脉行1 h的TCD微栓子监测,录制多普勒音频信号,分析栓子的出现及其与相关危险因素及斑块特征的关系.分析栓子与将来发生同侧颈动脉区域缺血性卒中风险的关系.结果 22例患者中12例(54.5%)探测到MES,66次TCD监测中23次(34.8%)探测到MES.基线时狭窄50%～69%组和狭窄≥70%组的MES比较差异无统计学意义(P=0.519),至6个月时比较差异有统计学意义(P=0.023),狭窄≥70%组较50%～69%组MES阳性发生率高(75.0%/16.7%).MES阳性组与MES阴性组在相关危险因素及治疗方面比较差异无统计学意义(P＞0.05);而两组在斑块的形态及内部结构比较差异有统计学意义(P＜0.05),Mes阳性组斑块多为不规则(75.0%)、非均质(66.7%).随访中MES阳性组有1例发生短暂性脑缺血发作(TIA),而无缺血性脑卒中发生.结论 TCD监测微栓子信号不能预测无症状颈动脉狭窄患者6个月内发生TIA和缺血性脑卒中的风险;MES的发生率与颈动脉狭窄程度、斑块的形态及结构有关,狭窄越重,MES的发生率越高,形态不规则及非均质斑块更易于发生MES.     

超声检测缺血性卒中微栓子信号分析

目的:观察缺血性卒中患者脑动脉微栓子信号（MES）的发生率并探讨其临床意义。方法:采用EME TC-4040型经颅多普勒超声（TCD）检测仪对56例发病7天以内,平均3.09（±1.5）天的缺血性卒中患者进行MES检测。结果:MES阳性率为26.8％,在大血管梗塞组（36.8％）高于小血管梗塞和TIA组（5.6％）;神经功能缺损程度中、重型组（35.9％）高于轻型组（5.9％）。结论:缺血性卒中患者的MES检测对诊断脑梗塞类型、估计预后有价值。     

短暂性脑缺血发作患者微栓子的监测

目的 探讨短暂性脑缺血发作(TIA)的发病机制.方法 广州医学院荔湾医院神经内科收治的52例符合TIA诊断标准的患者入选试验组.用经颅多普勒超声(TCD)检查颅内血管,彩色多普勒血流显像(CDFI)检查颈动脉血管,TCD-MF软件进行微栓子监测30 min,取大脑中动脉(MCA)或大脑后动脉(PCA)作监测血管.收集数据经SPSS 11.0版软件包分析处理,计数资料差异显著性检验采用χ2检验,计量资料差异显著性检验采用成组t检验,相关分析用Spearman等级相关分析,多因素分析用Logistic回归分析.以P＜0.05为差异具有统计学意义.结果 TIA组13例患者微栓子(MES)阳性(25%).Spearman等级相关分析显示MES出现与血管狭窄的严重程度呈正相关(CI=0.49,P＜0.01),Logistic回归分析显示责任血管狭窄是MES阳性的独立危险因素(P＜0.01).抗凝药物治疗10 d后11例患者(84.62%)MES为阴性.1年内TIA组MES阳性患者的脑血管事件再发率显著高于MES阴性患者(P＜0.05).结论 TIA的发生与颅内外动脉血管狭窄后引起的脑血流动力学改变、以及动脉粥样硬化斑块形成并脱落形成血液中流动的栓子有关.MES出现与颅内外血管狭窄程度有显著相关性,狭窄程度越高,MES出现的机率也越大.抗凝药物治疗可有效降低MES.MES阳性的TIA患者脑血管事件再发率明显增高.     

无症状和症状性颅内外动脉狭窄的微栓子监测

目的研究无症状和症状性颅内外动脉狭窄的微栓子出现频率与缺血性卒中的发生和病程时相之间的关系。方法对临床诊断为颅内外动脉狭窄的患者,采用双通道四深度及M Mode模式进行经颅多普勒超声(TCD)微栓子监测60 min,进行微栓子信号(MES)计数。根据病变部位将患者分为颈内动脉颅外段狭窄组(ICA组)和大脑中动脉狭窄组(MCA组),每组又分为无症状组、既往缺血性卒中组(≥30 d)和急性缺血性卒中组(<30 d)。结果共监测63例患者的74条狭窄动脉。ICA组:无症状、既往缺血性卒中、急性缺血性卒中MES阳性率分别为0(0/10)、0(0/7)、33%(6/18);在MCA狭窄组分别为14%(2/14)、14%(1/7)和39%(7/18)。60 min内的MES数目在ICA急性缺血性卒中组依次为3、9、8、10、1、40个,平均11 8个;在MCA无症状组为4、1个,既往缺血性卒中组为1个,急性缺血性卒中组为4、1、4、15、16、1、29个,平均10个。MES阳性率在ICA急性缺血性卒中和无症状组之间(P=0 .013)、急性缺血性卒中和既往缺血性卒中组(P=0 .031)之间有显著性差异。在MCA狭窄急性缺血性卒中和无症状组(P=0 .115)、急性缺血性卒中和既往缺血性卒中组(P=0 .214)之间无统计学差异。结论动脉性栓塞是颅内外大动脉狭窄所致缺血性卒中的重要发病机制。距卒中时间越近,MES的发生率越高,     

蕲蛇酶治疗缺血性脑血管病临床及TCD观察

目的:了解蕲蛇酶治疗缺血性脑血管病(ICVD)的经颅多普勒超声(TCD)有关参数及临床指标变化的情况并探讨其原因.方法:67例患者被分为具有可比性的2组,试验组32例予蕲蛇酶治疗,对照组35例予川芎嗪注射液、阿司匹林或藻酸双酯钠治疗,疗程10～15d;治疗前后分别监测血小板、血纤维蛋白原、TCD监测颅内外主要动脉的平均血流速度(Vm)、微栓子信号(MES)以及神经功能缺损评分的变化等指标.结果:治疗前后及2组各被检动脉的Vm均无明显变化(P＞0.05),但神经功能缺损评分治疗前后均有显著性差异(P＜0.05).试验组MES有显著减少(P＜0.05),且血小板减少有极显著性(P＜0.01).结论:蕲蛇酶对ICVD有较明显治疗作用;TCD可以作为ICVD在进行降纤或溶栓治疗过程中疗效判定的参考依据.     

TCD监测微栓子信号在缺血性

目的:探讨经颅多普勒(TCD)监测微栓子信号(MES)在缺血性脑血管疾病中的临床意义及凝血纤溶异常.方法:缺血性脑血管疾病患者69例,其中脑血栓43例,短暂性脑缺血(TIA)26例为脑血管病组和43例同年龄高血压、糖尿病或高血脂患者为对照组,分别监测TCD及检测凝血纤溶纤维蛋白原(Fg)和D-二聚体(D-D浓度).结果:脑血管病组的MES检出率较对照组显著增高,脑血栓组的MES检出率与TIA组无显著性差异.脑血栓组的Fg水平较对照组显著增高,TIA组的Fg水平与对照组无显著性差异,脑血栓组Fg水平较TIA组显著升高.脑血栓及TIA组的D-D浓度均较对照组显著增高,脑血栓组D-D浓度较TIA组显著升高.Logistic回归分析显示MES和高血压进入脑血管病发生的危险因素.结论:MES与缺血性脑血管疾病密切相关,可能是缺血性脑血管疾病的独立危险因子.     

经颅多普勒超声微栓子检测在颈动脉支架成形术中的应用

目的 应用经颅多普勒超声（TCD）动态观察脑保护滤网下颈动脉支架成形术中各操作阶段所产生的微栓子信号（MES）数量。 方法 对11例在脑保护滤网下颈动脉支架成形术患者术中采用TCD进行MES监测。将整个操作过程分为5个阶段，分别观察各操作阶段中患侧大脑中动脉的MES数量。 结果 11例患者术中各操作阶段均可产生MES。其中预扩、支架置入和后扩是栓子最易脱落的3个阶段，占MES总数量的68.7%。 结论 采用TCD可以有效地监测颈动脉支架成形术中各个阶段的MES数量，指导手术安全进行。     

双门深TCD检测脑动脉微栓子信号的敏感性和特异性

目的：研究双门深ＴＣＤ检测微栓子信号（ＭＥＳ）的敏感性和特异性。方法：采用双门深ＴＣＤ对２６例人工心瓣膜患者进行脑动脉微栓子检测,并与在线状态下有经验医师的人工判断（作为黄金标准）相比较。结果：双门深ＴＣＤ检测ＭＥＳ的敏感性为５９．６％,特异性为６４．４％。结论：双门深ＴＣＤ为识别、检测ＭＥＳ提供了新方法,但在线状态下的人工判断仍然是必需的。ＭＥＳ相对强度阈值对双门深ＴＣＤ检测ＭＥＳ敏感性和特异性的影响值得进一步研究。     

颈动脉粥样硬化斑块超声特征与微栓子信号的临床研究

目的:确定颈动脉粥样硬化斑块超声特征与MES的关系。材料和方法:选择急性颈内动脉系统脑梗塞患者193例,进行颈动脉彩色多普勒超声(CDI)检查,并对粥样斑块进行超声分型,进而应用TCD对存在狭窄的颈动脉远端MCA进行MES监测。结果:73.1%的患者检出颈动脉粥样硬化斑块,颈动脉狭窄的发生率为26.4%(51/193),其中48例共监测出MES(+)患者13例(27.1%),无回声/低回声斑块的病人比等回声/强回声损害的病人更易发现MES(P<0.01)。而且MES(+)病人存在较重的动脉狭窄,但差异并不显著(P>0.05)。结论:无回声/低回声斑块和MES之间可能存在一种潜在的临床关联性,提示MES可能是中风危险性增高的标志。     

Microembolic signal description: a reappraisal based on a customized digital postprocessing system

The high variability in presence and signature of microembolic signals (MES), detected with transcranial Doppler sonography (TCD) in the middle cerebral artery (MCA), cannot be explained with the currently available published data. We applied customized postprocessing on the radiofrequency (RF) signal of a standard TCD system. The spatial resolution was on the order of 2 mm, depending only on the length of the ultrasound (US) burst emitted. The amplitude of clutter-filtered RF signals was color-coded and plotted as a function of time and depth (range 30 mm). Additionally, 128 point fast Fourier transforms (FFTs) (50% temporal overlap) were calculated, visualizing both the background Doppler spectrum and the MES. We evaluated 122 gaseous MES from two patients during cardiac surgery and 52 particulate MES from four patients after carotid endarterectomy. Both MES categories showed comparable properties: they appeared in the RF amplitude plot as rather straight lines of increased intensity, indicating that the velocity remained approximately the same while they passed the US beam. The velocity calculated from the amplitude plot never exceeded that of the background Doppler spectrum. Various "MES patterns" could be identified with respect to the depth range at which the MES were visible. A quarter of the gaseous MES changed their direction at a specific depth, suggesting that the MES entered a branch (e.g., an M2 artery or the anterior cerebral artery). In the FFT analysis, these MES contained both positive and negative frequencies. It is concluded that MES show consistent signature patterns in the amplitude-time plots and that the previously reported variability of MES appearance in conventional Doppler systems is an artefact caused by relatively large signal amplitudes and sample volumes.     

TCD监测微栓子信号在缺血性脑血管疾病患者中的临床意义

目的：探讨经颅多普勒（TCD）监测微栓子信号（MES）在缺血性脑血管疾病中的临床意义及凝血纤溶异常。方法：缺血性脑血管疾病患者69例，其中脑血栓43例，短暂性脑缺血（TIA）26例为脑血管病组和43例同年龄高血压、糖尿病或高血脂患者为对照组，分别监测TCD及检测凝血纤溶纤维蛋白原（Fg）和D-二聚体（D-D浓度）。结果：脑血管病组的MES检出率较对照组显著增高，脑血栓组的MES检出率与TIA组无显著性差异。脑血栓组的Fg水平较对照组显著增高，TIA组的Fg水平与对照组无显著性差异，脑血栓组Fg水平较TIA组显著升高。脑血栓及TIA组的D-D浓度均较对照组显著增高，脑血栓组D-D浓度较TIA组显著升高。Logistic回归分析显示MES和高血压进入脑血管病发生的危险因素。结论：MES与缺血性脑血管疾病密切相关，可能是缺血性脑血管疾病的独立危险因子。     

Four-gated transcranial Doppler ultrasound in the detection of circulating microemboli.

OBJECTIVE: Embolus detection by transcranial Doppler ultrasound is very time consuming and semi-automated detection is mandatory. The device studied, a TC4040, Nicolet-EME, uses the four-gate technique and allows for audiovisual off-line verification of the recorded events. METHODS: Twenty controls, 10 patients with mechanical prosthetic heart valves and 12 patients with occlusive carotid artery disease were investigated by transcranial colour-coded duplex sonography and, subsequently, underwent a 1-h unilateral embolus detection from the middle cerebral artery using four-gate TCD. We investigated the Doppler spectrum background, microembolic signals (MES) and artefacts produced. A detection threshold of 5 dB or more was defined taking into account natural fluctuations of the Doppler spectrum. RESULTS: Sensitivity of the software was 91.9% and observer-software agreement on MES was 7.8% in the valve patients, and 77.7% and 7.5% in the carotid artery disease patients, respectively. Weaker MES were more likely not to be detected in all four channels. The artefact signal rejection rate was 62%. MES produced either positive or zero time delays in adjacent channels. Artefact signals produced either no delay, or a positive or a negative time delay. Duration of MES ranged from 1-88 ms. CONCLUSIONS: Besides refined recognition of MES using the time delay, four gates give faint MES no less than four opportunities to overcome the detection threshold. With this device's satisfying sensitivity, regions of interest in a 1-h recording can audiovisually be evaluated off-line in a few minutes by an investigator.     

Comparison of conventional extracorporeal circulation and minimal extracorporeal circulation with respect to microbubbles and microembolic signals

The intention of minimal extracorporeal circulation (MECC) is to reduce priming volume and minimize contact of blood with polymers and air in a closed system. In contrast to conventional extracorporeal circulation (ECC), a venous reservoir is missing. Thus, air trapping is limited and avoidance of bubble embolism is a major concern. This study investigates microbubbles (MBB) number and size in the venous and arterial lines of ECC and MECC compared to the number of microembolic signals (MES) in the right and left middle cerebral artery (MCA). Twenty patients undergoing coronary surgery were operated either with conventional ECC (cardiotomy reservoir, Rotaflow pump, Quadrox oxygenator, Quart filter) or MECC (Quart filter, Rotaflow pump, Quadrox oxygenator). Number and size of MBB were monitored in the venous and arterial lines with an ultrasound Doppler system. MES in right and left MCAs were measured by transcranial Doppler (TCD) monitoring. Patients undergoing MECC had additional sealing of the venous cannula by a ligature at the site of its insertion into the right atrium. There were no significant differences between groups with respect to age, X-clamping, bypass time and number of distal anastomoses. The number of MES and MBB in the arterial line was comparable between the groups. On the venous side, MECC-perfusion shows a significantly lower number of MBB. This could be explained with the additional sealing of the venous cannula. Furthermore, our data indicate that the MBB-volume reaching the pump will also appear in the arterial outflow and into the patient's MCA. For this reason, the avoidance of air contamination is a major concern for surgeons, anaesthesiologists and perfusionists.     

Neurological and neuropsychological examination and outcome after use of an intra-aortic filter device during cardiac surgery

Cerebral embolization of particles after cardiac surgery is frequently associated with neurological deficits. Aortic crossclamp manipulation seems to be the most significant cause of emboli release during cardiac surgery. The goal of this study was to demonstrate whether the use of an intra-aortic filter device has an effect on the magnet resonance imaging (MRI) and functional neurological outcome. Twenty-four patients undergoing cardiosurgical procedures using cardiopulmonary bypass (CPB) were selected: coronary artery bypass graft (CABG) surgery (n = 17), aortic valve replacement (AVR) surgery (n = 4) or combined procedures (n = 3). Patients were evaluated by diffusion weighted MRI of the brain, neurological examination and neuropsychological assessment regarding alertness as well as divided and selective attention before and five to seven days after surgery. The patients were divided into two groups. In group I, 12 patients received a filter through a modified 24 F arterial cannula immediately before the aortic crossclamp was released. Filters remained in the aorta until CPB was discontinued. Intraoperatively, bilateral middle cerebral artery transcranial Doppler (TCD) was monitored at baseline, at the beginning of CPB, at a timepoint when the aorta was crossclamped, when the filter was inserted and while the crossclamp was switched to partial clamping until the CPB was discontinued. TCD was used for detection of microembolic signals (MES). The captured material in the filter was examined histologically. Twelve patients served as controls without aortic filtration (group II). The MRI of the brain did not show any diffusion alterations in either group before or after surgery. No patient developed a focal neurological deficit or stroke. Intraoperative quantitative MES detection revealed a four to tenfold increase in patients of group I compared with group II (5-6 versus 0.5-1 MES/min) during the filter dwell time. There was no consistent pattern regarding the neurobehavioural sequelae. Filters showed arteriosclerotic debris in 75% of the patients. The use of the intra-aortic filter device did not show a positive effect on neurological, neuroradiographical and neuropsychological outcomes. The increase of the MES rate in group I patients may be due to microbubbles generated as microcavitations by the filter or the aortic filter cannula. The intra-aortic filter was able to capture atheromatous material in 75% of the patients.     

Middle cerebral artery anatomy and characteristics of embolic signals: a dual gate computer simulation study.

In terms of microembolic signal (MES) detection, the anatomy of the middle cerebral artery (MCA) mainstem has only scarcely been considered. The vessel itself, however, could be at least partly responsible for the enormous variation when calculating the essential time difference (deltat) values of MES using the dual-gate technique. Therefore, we studied the time characteristics of MES in a computer simulation applying an anatomically realistic vessel and a dual-gate TCD approach. Three different MCA anatomies and two MES to blood intensities were simulated as well as two different sample volume settings. The MES length (proximal sample volume t1; distal sample volume t2) and deltat were calculated for different angles of insonation and sample volume depths. The calculations of the time characteristics of MES showed extreme variation, with only modest changes of the insonation angle (t1 4-34 ms; deltat 9-27 ms) or the sample volume depth (t1 7-27 ms; deltat 6-32 ms). The variation could be considerably reduced with modified TCD settings i.e., a shorter gate separation combined with a shorter receiver gate time in the distal sample volume (deltat with changing insonation angles 6-19 ms; deltat with changing insonation depths 13-17 ms). These results not only urge us to a cautious interpretation of the properties of single MES, but also contribute to an understanding of the marked deltat variation using the dual-gate technique.     

Use of a dynamic bubble trap in the arterial line reduces microbubbles during cardiopulmonary bypass and microembolic signals in the middle cerebral artery

Neurological complications remain an important cause of morbidity and mortality of patients following cardiopulmonary bypass (CPB). Microemboli, as well as cerebral hypoperfusion, are the main postulated mechanisms. This study demonstrates that the insertion of a dynamic bubble trap (DBT) into the curcuit reduces microbubbles in the arterial line and microembolic signals (MES) in the middle cerebral arteries (MCAs). We investigated 12 patients during coronary artery bypass grafting (CABG). The DBT was inserted between the arterial filter and the arterial cannula. For detection of microemboli before and after the DBT, a special ultrasound Doppler device was used. MES were detected by transcranial Doppler monitoring in both MCAs of the patients. Microbubbles and MES were counted during bypass. These data were compared to 12 patients who were operated in a previous period without the use of a DBT. There were no significant differences in both groups with respect to gender, age, crossclamp and bypass time and number of anastomoses. In the group without a DBT in the circuit, a mean of 6311 microbubbles per operation could be observed distal to the arterial filter, corresponding to 282 MES. After inclusion of a DBT, we could register, in the second group, 8496 microemboli proximal and 2915 distal of the DBT, corresponding to 89 MES per operation. The reduction rate of microbubbles in the tubing was 65.7%, corresponding to a reduction in MES of about 86.2%. We conclude that the insertion of a DBT in the arterial line of CPB circuit protects the cerebrovascular system from microembolic events, as demonstrated by lower MES counts.