经颅多普勒超声对颅外段颈内动脉狭窄诊断价值的评估

目的评价经颅多普勒超声(TCD)对颅外段颈内动脉(ICA)狭窄、闭塞的诊断价值及探讨TCD评价动脉狭窄程度的参数。方法对临床有缺血性脑血管病症状的患者,先做TCD检查,筛选出可疑有颅外段颈内动脉病变的患者．再行数字减影血管造影(DSA)及(或)多层面螺旋CT血管成像(CTA)检查,确定颅外段颈内动脉狭窄的诊断,并计算狭窄程度,然后将DSA／CTA证实颈内动脉狭窄的患者的TCD资料进行回顾性分析。结果(1)脑血流速度:单侧ICA闭塞患者,ICA血流信号消失或极低(<20cm／s);重度狭窄者,狭窄程度与流速呈正比:狭窄程度越重,收缩期峰值流速(PSV)增高越明显;中度狭窄者局部流速轻度增加;轻度狭窄者血流速度与正常流速比较无明显变化。(2)ICA狭窄段PSV与ICA狭窄远端PSV的比值:重度狭窄为3．13-4．56,中度狭窄为2．24-2．73,轻度狭窄无明显变化。(3)侧支循环开放:颈动脉完全闭塞中93．1％侧支循环开放,狭窄程度>90％者86．6％存在侧支循环开放,70％-90％狭窄者74．3％侧支循环开放,轻、中度狭窄者无1例侧支循环开放。(4)频谱图形:重度狭窄患者,TCD表现为频谱增宽、湍流改变;中度狭窄者可出现涡流改变;轻度狭窄者TCD仅表现为层流消失,频谱呈高强度血流充填信号,声频钝。结论TCD对颅外段ICA重度狭窄、闭塞的患者具有较高的诊断价值．可为介入治疗或手术治疗提供参考依据。     

症状性颈内动脉重度狭窄或闭塞患者的侧支循环评估

目的 探讨症状性颈内动脉重度狭窄或闭塞患者的侧支循环评估。方法 选取中国人民解放军火箭军总医院(原第二炮兵总医院)神经内科住院的症状性颈内动脉重度狭窄或闭塞患者41例,首先采用德国EME公司TC-2000S型经颅彩超多普勒(Transcranial Doppler,TCD)仪,常规检测双侧颈总动脉及颈内动脉、颅内Willis环及相关主要动脉分支,进行侧支循环评估; 进一步采用德国西门子64层螺旋CT扫描机行CT血管成像(CT angiography in diagnosis,CTA)检查,明确颈内动脉病变的存在; 再应用PHILIPS FD20 DSA数字减影机行全脑血管造影术并进行侧支循环评估,评估颈内动脉闭塞性病变后的侧支循环代偿能力,评估眼动脉侧支循环通路的开放情况及作用。结果 41例患者颈内动脉重度狭窄24例,颈内动脉闭塞17例。TCD显示ACoA开放5例,占12.2%,DSA为4例,占9.76%; TCD显示PCoA开放5例,占12.20%,DSA为3例,占7.32%; TCD判断OA开放25例,占60.98%,DSA为23例,占56.11%; TCD提示LA开放3例,占7.32%,DSA提示2例,占4.88%; TCD显示无侧支循环开放者16例,占39%,DSA为14例,占34.15%。TCD和DSA在评估侧支血管开放数量方面无显著差异(P>0.05)。TCD评估眼动脉开放在颈内动脉重度狭窄和闭塞的患者中有显著差异(P<0.05)。颈内动脉重度狭窄患者和闭塞患者的TCD及DSA侧支循环评估无显著差异(P>0.05)。OA单独开放患者较无OA开放患者PI值高。狭窄组MCA的PI值低于闭塞组,狭窄组OA最高流速低于闭塞组(P<0.05)。颈内动脉狭窄组OA单独开放数量<闭塞组(P<0.05)。结论(1)TCD与DSA在评估侧支循环血管开放数量方面的作用基本一致,TCD可作为CTA和DSA侧支评估之前的初筛手段,可以独立作为侧支循环评估的检查手段;(2)眼动脉是否参与侧支循环及眼动脉的的开放程度与颈内动脉本身病变程度有关。眼动脉作为次级侧支通路参与侧支循环的程度与病情严重程度具有一定相关性,在颈内动脉慢性闭塞性患者眼动脉单独开放的比例>重度狭窄的患者,重度狭窄的患者OA最高流速低于闭塞组患者,这说明颈内动脉慢性闭塞性患者其OA开放后提供的灌注代偿作用相对更大。     

颈内动脉重度狭窄或闭塞患者侧支循环与搏动指数及持续注意功能的相关性研究

目的探讨颈内动脉重度狭窄或闭塞患者侧支循环与搏动指数(PI)及持续注意功能的相关性。方法对135例颈内动脉重度狭窄或闭塞患者进行DSA检查并根据侧支循环开放情况分组。另选择30名健康老年人作为对照组。采用TCD检查检测双侧大脑中动脉收缩期和舒张期血流速度(Vs和Vd)、平均血流速度(Vm)和PI。采用持续性操作测验的遗漏数、认错数、平均反应时评估持续注意功能。对结果进行比较分析。结果 (1)135例颈内动脉重度狭窄或闭塞患者根据侧支循环开放情况分为前交通动脉(AcoA)开放组(31例)、后交通动脉(PcoA)开放组(20例)、AcoA+PcoA开放组(19例)、初级侧支循环开放组(即AcoA、PcoA、AcoA+PcoA开放)(70例)、次级侧支循环开放组(主要包括眼动脉、软脑膜吻合支和新生供血血管)(15例)、初级+次级侧支循环开放组(13例)和无侧支循环开放组(37例)。(2)与对照组比较,其余各组患者的Vs、Vd、Vm和PI均显著降低(均P0.05)。与无侧支循环开放组比较,AcoA开放组、初级侧支循环开放组的Vd及AcoA+PcoA开放组的Vd、Vm均明显升高,AcoA开放组、AcoA+PcoA开放组、初级侧支循环开放组及初级+次级侧支循环开放组的PI均明显降低(均P0.05)。与PcoA开放组比较,AcoA开放组、AcoA+PcoA开放组的PI均明显降低(均P0.05)。与次级侧支循环开放组比较,初级侧支循环开放组的Vs、Vd、Vm和初级+次级侧支循环开放组的Vd、Vm均明显升高,初级侧支循环开放组和和初级+次级侧支循环开放组的PI均明显降低(均P0.05)。(3)与对照组比较,其余各组患者的遗漏数、认错数和平均反应时均显著增加(均P0.05)。与无侧支循环开放组比较,AcoA开放组、AcoA+PcoA开放组及初级侧支循环开放组的遗漏数、认错数和平均反应时均明显减少;初级+次级侧支循环开放组的遗漏数和认错数均明显减少(均P0.05)。与PcoA开放组比较,AcoA开放组的遗漏数和认错数均明显减少;AcoA+PcoA开放组的遗漏数、认错数和平均反应时均明显减少(均P0.05)。与AcoA+PcoA开放组比较,AcoA开放组的遗漏数、认错数和平均反应时均明显增加(均P0.05)。与次级侧支循环开放组比较,初级侧支循环开放组的遗漏数、认错数和平均反应时均明显减少;初级+次级侧支循环开放组的遗漏数和认错数均明显减少(均P0.05)。(4)AcoA开放组、初级侧支循环开放组和次级侧支循环开放组的PI与平均反应时呈正相关(r=0.441,r=0.364,r=0.552;均P0.05)。PcoA开放组和无侧支循环开放组的PI与遗漏数呈正相关(r=0.668,r=0.397;均P0.05);与认错数呈正相关(r=0.509,r=0.480;均P0.05)。结论颈内动脉重度狭窄或闭塞患者患侧高PI可反映其持续注意功能受损。     

Takayasu氏动脉炎的脑血流动力学改变

目的Takayasu氏动脉炎是主动脉及其主要分支的炎性血管病变,本研究用经颅超声多普勒(TCD)探测16例大动脉炎患者脑血流动力学的特征性改变。方法16例患者均行TCD检测,分析其收缩期血流速度(Vs)、舒张期血流速度(Vd)、脉动指数(PI)、频谱形态等改变,5例患者同时行主动脉造影。结果累及主动脉弓多支血管者,TCD表现为Willis环主干血管的Vd升高(P<0.05和P<0.01),PI均降低(P<0.001),频谱表现为波型衰减、波峰变钝、峰值后移,呈几乎无波动的频谱改变;累及主动脉弓单支血管者,TCD仅表现为锁骨下动脉狭窄伴颈内动脉及椎动脉、基底动脉分叉处狭窄。结论TCD检测显示颅内出现异常的血流动力学改变,即Vd升高、PI明显减低或锁骨下动脉狭窄、频谱出现特征性的改变等,结合临床即可诊断为Takayasu氏动脉炎。     

应用彩色多普勒影像和经颅多普勒超声检查评估颈内动脉支架置入术后效果

目的采用彩色多普勒影像(CDFI)联合经颅多普勒超声(TCD)评价颈内动脉狭窄患者颈动脉支架置入术(CAS)的治疗效果。方法回顾性分析经数字减影血管造影(DSA)确诊具有脑缺血症状的中度颈内动脉狭窄且接受CAS治疗的患者35例,采用CDFI联合TCD方法测量CAS术前、术后颈内动脉狭窄局部管径、狭窄率、狭窄段收缩期峰值流速及同侧大脑中动脉的收缩期峰值流速、搏动指数进行对比分析,同时与DSA结果进行对比。结果颈内动脉狭窄患者行CAS术后原狭窄处管径明显增宽,原狭窄处血管内径由术前(1.82±0.75)mm增至术后(3.97±0.73)mm,P<0.001。颈内动脉狭窄处及患侧大脑中动脉的收缩期峰值流速、搏动指数恢复正常,94.3%侧支循环关闭。颈内动脉狭窄处收缩期峰值流速由术前(186.49±63.85)cm.s-1降至术后(80.63±31.46)cm.s-1,P<0.001;患侧大脑中动脉的收缩期峰值流速由术前(59.23±23.64)cm.s-1升至术后(85.5±20.59)cm.s-1,P<0.001;大脑中动脉的搏动指数值由术前(0.58±0.29)升至术后(0.83±0.17),P<0.001。结论 CDFI及TCD检测提示CAS术后颈内动脉狭窄处血管血流动力学及血管结构得到改善,CDFI联合TCD可以作为评价及随访CAS术后疗效的有效手段。     

脑出血患者脑血流速度的观察

目的 观察脑出血后脑主要动脉的血流速度变化,进而研究脑血流动力学变化的临床价值。方法 采用经颅超声多普勒(transcranial Doppler,TCD)分别对216例脑出血患者和80名健康对照者的大脑中动脉、大脑前动脉、大脑后动脉、颈内动脉、基底动脉和椎动脉等颅内主要动脉的血流速度进行检测分析,记录包括收缩期峰速(Vs)、舒张期末流速(Vd)及搏动指数(PI)等血流参数及频谱形态。结果 脑出血组患者收缩期峰速与舒张末期流速与对照组比较均降低,差异有显著性意义(P<0.001)。脑出血组有164例患者(7.93％)颅内动脉血流速度降低,其中51例(23.61％)发生于脑出血早期,以舒张期末流速降低为主,113例(52.31％)发生于脑出血的中、后期,表现为普遍性流速降低。另有52例(24.07％)脑血流速度基本正常。结论 多数脑出血患者脑组织处于低循环状态,其程度与病情相关,因此对脑出血患者进行血流动力学监测有助于指导治疗及判断预后。     

经颅多普勒联合CT灌注成像对单侧颈内动脉重度狭窄或闭塞患者脑血流动力学评价

目的 经颅多普勒(TCD)联合CT灌注成像(CrP)对单侧颈内动脉(ICA)重度狭窄或闭塞患者脑血流动力学评价.方法 经TCD检测为单侧ICA重度狭窄或闭塞患者19例,分症状组(9例)及无症状组(10例),行头颅CT血管成像(CTA)和CTP检查.15例健康志愿者为对照组.比较症状组和无症状组患侧之间、症状组和无症状组患侧与对照组TCD及CTP参数.结果 TCD示症状组患侧大脑中动脉(MCA)平均血流速度(Vm)低于对照组(P＜0.001),而无症状组MCA Vm低于对照组,但差异无统计学意义(P＞0.05);症状组和无症状组MCA搏动指数(PI)均低于对照组(P＜0.05).症状组患侧MCA Vm明显低于无症状组(P ＜0.001),与颅内侧枝循环有关.症状组和无症状组与对照组CTP参数分析,症状组患侧脑血流量(CBF)减低(P＜0.05),而无症状组CBF无明显改变(P＞0.05);症状组和无症状组平均通过时间(MTI)及达峰时间(TIP)延长(P＜0.05),但两组脑血容量(CBV)与对照组比较差异无统计学意义(P＞0.05).结论 TCD与CTP结果有良好的一致性,二者联合应用可以综合评估单侧颈动脉狭窄或闭塞患者脑灌注情况,为临床选择有效治疗方案提供科学依据.     

经颅多普勒超声椎动脉血流速度减低的病理机制与鉴别诊断

目的 探讨缺血性卒中患者椎动脉血流速度减低的病理机制及超声鉴别诊断.方法 纳入经颅多普勒超声(transcranial Doppler ultrasound,TCD)显示椎动脉血流速度减低的缺血性脑卒中患者168例,以数字血管减影(digital subtraction angiography,DSA)为"金标准"进行分组,比较各组椎动脉峰值流速(systolic velocity,Vs)及血管搏动指数(pulsatility index,PI)的差异.结果 椎动脉正常组41 例(24.4%);椎动脉发育不良/变异组55例(32.7%);椎动脉狭窄组72例(42.8%).正常组双侧椎动脉Vs及PI无统计学差异(P＞0.05);狭窄组患侧椎动脉Vs 低于健侧(P=0.000),PI 双侧对比无统计学差异(P＞0.05);发育变异组患侧椎动脉Vs 低于健侧(P=0.001),PI则高于健侧(P=0.004).不同病变类型血流动力学的比较显示,椎动脉起始段≥70%狭窄者、椎动脉变异者及颅内段闭塞者Vs均低于正常椎动脉(均P＜0.05),椎动脉起始段轻-中度狭窄者Vs与正常椎动脉无统计学差异(P=0.195);正常椎动脉PI与上述各组比较均有统计学差异(P＜0.05),椎动脉起始段≥70%狭窄者PI最低(0.77±0.37),低于正常椎动脉、椎动脉变异、椎动脉起始段轻-中度狭窄及颅内段闭塞者(均P＜0.05);而颅内段闭塞者PI则明显高于上述各组(1.47±0.13,P=0.000).结论 TCD椎动脉血流速度减低可见于椎动脉正常、发育不良/变异、起始段重度狭窄/闭塞以及颅内段闭塞,双侧椎动脉血流速度和PI对称性的比较对于鉴别诊断具有重要意义.     

经颅多普勒超声对外伤性颈动脉海绵窦介入治疗前血流评估的意义

目的总结经颅多普勒在TCCF介入栓塞手术前评估颅内血流代偿的初步应用。方法对16例TCCF患者介入手术之前行TCD检查,取得双侧大脑中动脉(MCA)血流数值,及压迫患侧颈动脉时双侧MCA血流速度数值。通过数值对比,评价颅内血流代偿状况。结果 3例患者术前TCD显示患侧MCA血流速度减慢,12例压迫患侧颈动脉时双侧MCA流速接近,1例压迫患侧颈动脉时双侧MCA流速差异较大,经间断压迫患侧颈动脉,流速趋于接近。结论 TCD具有无创伤、安全、方便、可重复等特点,并能实时反映脑血流动力学状态和Willis’环侧支循环代偿情况,作为TCCF指导介入治疗术前及疗效评估具有重要的临床应用价值。     

颈动脉严重狭窄或闭塞的脑血流动力学改变

目的分析颈内动脉严重狭窄或闭塞(ICA SO)后颅内血液动力学的改变,以提高经颅多普勒超声(TCD)对ICA SO的检出率和准确性。方法ICA SO患者75例,全部经颈部血管彩超检查证实,其中12例经脑血管造影(DSA)或核磁血管造影(M RA)进一步确诊。双侧病变7例,单侧病变68例,共有病变血管82条(狭窄42条,闭塞30条)。全部行TCD检查。结果(1)狭窄或闭塞侧大脑中动脉(M CA)的收缩期血流速度(SPV)及脉动指数(P I)明显低于对侧;(2)前交通动脉(ACoA)开放的患者健侧大脑前动脉(ACA)的峰值流速明显快于ACoA未开放的患者,P I值低于后者;(3)眼动脉之前的ICA SO,患侧虹吸段血流与对侧相比具有明显的低流速低搏动改变;眼动脉之后的ICA SO,患侧虹吸段与对侧相比具有明显的低流速高阻力改变,发出眼动脉之前和之后的ICA SO二者虹吸段收缩期流速无明显差异,但前者P I值明显低于后者;(4)颈外-颈内动脉(ECA-ICA)侧支开放的患者患侧与健侧滑车上动脉(S trA)血流速度无明显差异,但P I值明显低于健侧;(5)前交通动脉(ACoA)开放占50.67%(38/75),后交通动脉(PCoA)开放占52.00%(39/75),颈外-颈内动脉侧支(ECA-ICA)开放占75.44%(43/57)。结论增强对ICA SO时颅内血液动力学改变的认识能提高对ICA SO的检出率和准确性。     

颈动脉支架置入术对脑梗死患者脑血流动力学变化的随访观察及与临床预后的相关性分析

目的 随访观察颈动脉狭窄脑梗死患者支架置入术后的颅内血流动力学及脑血管反应性(cerebral vascular reactivity,CVR)的变化,比较介入治疗对颈动脉狭窄患者临床预后的影响。方法 选取本院收治的103例颈动脉狭窄的脑梗死患者,根据患者及家属的治疗意愿分为手术组50例和药物组53例; 手术组均接受颈动脉支架置入术(carotid artery stenting,CAS)及药物的治疗,药物组仅接受药物治疗,记录2组的NIHSS评分变化、脑卒中和死亡事件; 所有手术患者均在术前、术后3 d、1、3、6、12个月进行CDFI和TCD检查,测量颈动脉狭窄局部管径、狭窄段收缩期峰值流速(peak systolic velocity,PSV)、阻力指数(resistance index,RI)及同侧大脑中动脉(MCA)的PSV、搏动指数(pulsatilityt index,PI)及CVR,比较手术前后的血流动力学变化。结果 2组NIHSS评分变化均呈下降趋势(P<0.05),术后3、6、12个月手术组NIHSS评分明显低于药物组(P<0.05); 术后颈动脉原狭窄处内径明显增宽,PSV及RI低于术前,患侧大脑中动脉PSV、PI及CVR 高于术前(P均<0.05); 手术组手术前后的CVR与美国国立卫生研究院卒中量表评分呈负相关(r=-0.84,-0.75,-0.66,-0.78,-0.61,P<0.05)。结论 CAS治疗后颈动脉狭窄患者颈部血管结构及血流动力学明显改善,可有效改善脑梗死患者的中远期预后,且术后CVR的改变可用于预测CAS治疗后的中远期疗效。     

Assessment of ophthalmic artery collateral pathway in the hemispheric cerebral hemodynamics in patients with severe unilateral carotid stenosis

The role of ophthalmic artery collateral pathway in hemispheric hemodynamics in patients with severe carotid stenosis is controversial. The aim of the present study was to address this question comparing the asymmetry of the velocity in middle and anterior cerebral arteries (MCAs and ACAs) and cerebrovascular reactivity (CVR) in MCA on stenotic side in the patients with unilateral severe stenosis of internal carotid artery (ICA) in patients with and without ophthalmic artery collateral pathway. The cohort of 118 patients with carotid stenosis was prospectively assembled. Fifty patients who had severe unilateral ICA stenosis (71%-99%) by Duplex Ultrasound (DUS) were observed by transcranial Doppler (TCD). Cerebral blood flow velocity in MCA and ACA in both sides, direction of blood flow in ophthalmic artery (OA) and CVR on the side of stenosis were determined. There were 14 patients with retrograde blood flow in OA (Group I). The remaining 36 patients with anterograde flow in OA composed Group II. The degree of interarterial asymmetry of peak and mean velocity (Vpeak and Vmean) in MCA and ACA and CVR in MCA were compared in both groups. The degree of ACA asymmetry by Vpeak was 44.0% +/- 6.9% in Group I and 38.3% +/- 3.9% in Group II (p = 0.49), by Vmean 40.3% +/- 6.7% and 36.6% +/- 3.8% (p = 0.63) respectively. The degree of MCA asymmetry by Vpeak was 24.2% +/- 2.8% in Group I and 19.5% +/- 5.0% in Group II (p = 0.42), by Vmean 23.5% +/- 2.9% and 20.6% +/- 5.1% (p = 0.63) respectively. CVR in Group I was 26.1% +/- 6.1%, in Group II 29.0% +/- 6.7% (p = 0.65). The ophthalmic collateral pathway has no influence on hemispheric cerebral hemodynamics in patients with severe unilateral carotid stenosis.     

颈内动脉狭窄相关性脑缺血病变的临床分析

目的 探讨颈内动脉狭窄致脑缺血病变的临床特点及发生机制,为临床指导治疗及判断预后提供依据.方法 回顾分析111 例经CT 血管造影(CTA)证实的颈内动脉狭窄患者的颅内Willis 环形态、TCD 资料及临床表现.结果 颈内动脉轻、中、重度狭窄组脑梗死发生率分别为14.7% 、30.6% 、46.3%,三组间差异具有显...     

DSA对单侧颈内动脉系统大动脉狭窄或闭塞后侧支循环建立的应用价值

目的 探讨DSA对单侧颈内动脉系统大动脉狭窄或闭塞后侧支循环建立的应用价值,探讨三级侧支循环在单侧颈内动脉开口部位狭窄或闭塞及大脑中动脉M1段狭窄或闭塞中的特点.方法 分别对56例颈内动脉开口处狭窄或闭塞及94例大脑中动脉M1段狭窄或闭塞的患者进行脑血管造影检查,根据其狭窄程度分析其侧支循环建立的情况.结果 颈内动脉开口部位闭塞组大脑动脉环开放率约38.5%,颅内外沟通开放率30.8%,软脑膜吻合支开放率约30.8%;重度狭窄组大脑动脉环开放率35.1%,软脑膜吻合支开放率16.2%,颅内外沟通开放率约5.4%;中轻度狭窄组无侧支循环建立.大脑中动脉M1段闭塞组大脑动脉环开放率5%,软脑膜吻合支开放率95%;重度狭窄组仅软脑膜吻合支开放,开放率约61%;轻中度狭窄组无侧支形成.结论 在颈内动脉开口部位重度狭窄或闭塞的病例中,一级侧支循环的开放代偿最为重要,二级侧支循环起着重要的辅助作用.在大脑中动脉M1段重度狭窄或闭塞的病例中,二级和三级侧支循环的开放起主要的代偿作用.     

Cognitive decline and cerebral vasoreactivity in asymptomatic patients with severe internal carotid artery stenosis

The aim of the study was to correlate cognitive decline and cerebral vasoreactivity in 150 asymptomatic right-handed patients with severe ≥70 % unilateral internal carotid artery (ICA) stenosis and to evaluate the role of intracranial collateral circulation during cognitive testing. Cognitive assessment was performed by means of Montreal Cognitive Assessment (MoCA) and Mini Mental State Exam (MMSE) scales. Cerebrovascular reactivity (CVR) and intracranial collateral circulation were evaluated by means of breath holding index (BHI) and transcranial color Doppler (TCD) sonography. The results were compared with 150 right-handed controls matched for demographic variables and vascular risk factors. Patients with severe unilateral ICA stenosis had MMSE scores within a normal range, but MoCA scores were lower than normal. By examining the side of the observed stenosis, it has been noted that patients with left-sided ICA stenosis had lower MoCA scores in categories of language and episodic memory performance, while patients with right-sided ICA stenosis had lower MoCA scores in a category of visual–spatial skills. All patients had BHI values lower than normal. Subjects with a single intracranial collateral artery recruited had slightly better cognitive results than the patients with two or more collateral arteries activated. Results of the study showed that altered cerebrovascular reactivity and cerebral hypoperfusion might be responsible for the reduction of specific cognitive functions ipsilateral to the ICA stenosis, therefore BHI and MoCA might be useful tools when screening for cognitive decline in asymptomatic patients with severe ICA stenosis.     

经颅多普勒超声评估单侧颈内动脉颅外段闭塞患者颅内侧支循环的临床意义

目的 探讨经颅多普勒超声(TCD)评估单侧颈内动脉颅外段闭塞(ICAO)患者颅内侧支循环的临床价值.方法 回顾性连续纳入2018年1月至2020年12月就诊于苏州大学附属第一医院卒中中心、行颈部血管超声检查为单侧ICAO及数字减影血管造影(DSA)证实患者145例,其中症状组109例,无症状组36例.记录TCD评估颅内...     

Cerebral hemodynamics after contralateral carotid endarterectomy in patients with symptomatic and asymptomatic carotid occlusion: a 10-year follow-up.

We sought to investigate whether carotid endarterectomy (CEA) can achieve long-term cerebral hemodynamic improvement and reduce recurrence of cerebral ischemic events in symptomatic and asymptomatic patients with severe (>70%) carotid artery stenosis contralateral to carotid occlusion (CO). Thirty-nine patients with severe carotid lesion contralateral to CO were studied before (1 day) and after CEA (at 7 days, 1, 3 and 6 months, and then yearly thereafter). Collateral flow and cerebral vasomotor reactivity (VMR) were assessed by transcranial Doppler sonography (TCD). A total of 32 unoperated patients with severe carotid lesion contralateral to CO, who were comparable with respect to age and sex, served as a control group. The average period of TCD follow-up was 10 years and was obtained in all patients; during this period, major clinical events (stroke, acute myocardial infarction and death) were also recorded. The proportion of patients with collateral flow via the anterior communicating artery increased significantly from 61.5% before to 89.7% after CEA (P = 0.01). Cerebral VMR ipsilateral to CO improved in 85.7% of patients (30 of 35) within 30 days of CEA, and in all patients within 90 days. No significant spontaneous VMR recovery was recorded in the control group. After the initial recovery, no significant change in VMR was observed in the surgical group or the control group during the follow-up. In conclusion, in patients with severe carotid stenosis, CEA contralateral to symptomatic and asymptomatic CO determines a durable cerebral hemodynamic improvement not only on the side of the CEA but also on the contralateral side, with no difference between symptomatic and asymptomatic patients.     

Cerebral hemodynamics in ischemic cerebrovascular disease

During the past decade, technological advances have made it possible to measure regional cerebral hemodynamics in individual patients. Studies performed with these techniques have demonstrated that the degree of carotid stenosis correlates poorly with the hemodynamic status of the ipsilateral cerebral circulation. The primary determinant of cerebral perfusion pressure and blood flow under these circumstances is the adequacy of collateral circulatory pathways. Since collateral circulation varies from patient to patient, there is no critical degree of carotid stenosis that consistently produces hemodynamic compromise of the cerebral circulation. It is, thus, time to abandon the concept of the hemodynamically significant carotid stenosis as it relates to the pathogenesis and treatment of cerebrovascular disease. Measurements of regional cerebral hemodynamics have provided new insight into the pathogenesis of transient ischemic attacks and generated some preliminary data on the prognostic and therapeutic importance of chronic reductions in regional cerebral perfusion pressure. Further investigations into the importance of hemodynamic factors in ischemic stroke can now be based on accurate assessment of cerebral (not carotid or vertebrobasilar) hemodynamics in the context of other coexisting epidemiological, clinical, hematological, and angiographic risk factors.     

Cerebrovascular reserve capacity

Cerebrovascular reserve capacity (CVR) describes how far cerebral perfusion can increase from a baseline value after stimulation. Measurement of cerebral blood flow (CBF) can be done by PET or SPECT. Noninvasive and easily performed transcranial Doppler sonography (TCD) is mostly used as indirect perfusion measurement. Stimulation of cerebral perfusion is often done by CO2 inhalation or acetazolamide injection. Alternative stimuli are breath holding or cerebral activation by hand-gripping. Normal values for these tests are presented. The hemodynamic effect of stenoses of the internal carotid artery (ICA) can be estimated using CVR. The relevance of CVR is discussed controversially, since cerebral infarction due to stenosis of arteries supplying the brain is probably mostly of embolic, not hemodynamic origin. The indication for carotid artery surgery according the NASCET and ECST investigations takes into account only the degree of the stenoses and not the CVR. According to recent studies, the risk of cerebral infarction in these patients is considerably higher with reduced CVR. Therefore, CVR can be used as an additional parameter if the indication for surgery is not defined, especially in asymptomatic carotid artery stenosis. It seems also possible to identify patients who might profit from an extra-intracranial bypass operation and high-risk patients for cerebral ischemia with cerebral microangiopathy. Furthermore, the risk of cerebral infarction during carotid artery surgery and also during heart surgery can be estimated using CVR. More studies with a higher number of patients are needed to confirm the potential predictive diagnostic value of CVR in order to establish CVR measurement as part of a routine diagnostic neuroangiologic program.