Relation between middle cerebral artery blood flow velocity and stump pressure during carotid endarterectomy.

BACKGROUND AND PURPOSE: Many patient monitoring techniques have been used for detecting cerebral hypoperfusion during carotid endarterectomy. We compared middle cerebral artery blood flow velocities with carotid artery stump pressures to evaluate the indications for common carotid artery cross-clamp shunting and the probable hemodynamic causes of cerebrovascular complications. METHODS: Blood flow velocities were monitored with transcranial Doppler ultrasound and carotid stump pressures were measured at the time of common carotid artery cross-clamping during 97 carotid endarterectomy procedures. Stump pressures measured with the gauge zero reference at the common carotid artery level were correlated with the percentage change of velocities. RESULTS: Middle cerebral artery blood flow velocities usually decreased upon common carotid artery cross-clamping, depending on collateral availability and the autoregulation response. The best fit of the data was to an exponential function concave to the pressure axis, with velocity as a percentage of the pre-cross-clamp value reaching zero at 15 mm Hg stump pressure (r = 0.85 and p less than 0.001). CONCLUSIONS: There is a less critical margin of error with percentage middle cerebral artery blood flow velocity decreases than with stump pressure measurements. This relation establishes changes in middle cerebral artery blood flow velocities as a reliable parameter for judging the effects of carotid cross-clamping on cerebral blood flow and providing an excellent indicator as to the necessity for shunting.     

Regional cerebral blood flow and stroke index after left carotid artery ligation in the conscious gerbil

We measured the regional cerebral blood flow in both hemispheres of Mongolian gerbil subjected to permanent left caratoid artery ligation, using [³H]nicotine as the tracer. At 1,3 and 6 h post-ligation, neurological signs were recorded and a stroke index score was tallied for each animal.In conscious control gerbils, mean cerebral blood flow on the left side was1.10 ± 0.08 (S.E.M.) ml·g⁻¹·min⁻¹ at the cerebral cortex0.58 ± 0.02 at the hippocampus and0.69 ± 0.04 at the diencephalon. Animals with a stroke index score exceeding 10 were considered symptomatic. We noted a close relationship between regional cerebral blood flow and the stroke index score. In symptomatic animals, regional cerebral blood flow in the ischemic hemisphere at 1,3 and 6 post-ligation was less than 0.21 ml·g⁻¹·min⁻¹ at the cortex and diencephalon, and less than 0.09 ml·g⁻¹min⁻¹ at the hippocampus.We suggest that unilaterally ligated gerbils manifesting a stroke index score greater than 10 represent a good experimental model for the study of ischemia.     

Unilateral carotid artery ligation in the Mongolian gerbil as a model for testing infarction-reducing therapies

This study evaluates infarct size measurement as an indicator of cerebral ischaemia outcome in a placebo-controlled trial of potential cerebral protection in the unilateral carotid artery ligation in the Mongolian gerbil. Ibuprofen was used in an effort to manipulate infarct size as this agent has been shown to reduce ischaemia in myocardial infarction. Using measurements obtained through an infarct-sizing technique and a statistical power analysis of the method, the sample sizes needed to obtain significant results were projected for this model. In this case, it was not possible to demonstrate an effect of ibuprofen on infarct size although a tendency towards larger infarct size in ibuprofen-treated compared with placebo-treated gerbils was observed (36.1 +/- 10.1% versus 30.0 +/- 17.5%). The sample sizes needed to find significant changes in infarct size indicate that this model finds a practical use in studying therapies which will alter infarct size by at least 50%. For example, to detect a 30% change in infarct size, 33 successfully infarcted gerbils per group would be needed, but a 50% change would require a more tenable 13 infarcted gerbils per group. However, given the 40% infarction rate of occluded gerbils seen in this study, almost 33 gerbils per group would be required to detect a 50% change. In addition, somatosensory evoked potential was compared with neurological examination as a predictor of infarction. It would be helpful to be able to pre-screen for infarcted gerbils immediately after occlusion in order to direct infarcted gerbils into control and treated groups. Somatosensory evoked potential successfully predicted infarction with a 90% accuracy in 21 gerbils compared with neurological evaluation which was 100% accurate. But the somatosensory evoked potential prediction was made within 15 min of occlusion as opposed to the 6 h of observation during which the neurological evaluation was made.     

Vertebral artery stump syndrome in acute ischemic stroke

Although the carotid artery stump as an embolic source for ischemic stroke has been well described, there have been few systematic reports of a similar syndrome in the posterior circulation (PC) after vertebral artery (VA) origin occlusion. The aim of this study was to identify the incidence and characteristics of acute ischemic stroke with VA stump syndrome. Of 3463 consecutive patients who were admitted within 7 days after onset, 865 patients with acute ischemic stroke in the PC were enrolled. The diagnostic criteria of VA stump syndrome included: (1) acute ischemic stroke in the posterior circulation; (2) the VA origin occlusion identified on MRA, duplex ultrasound, CT angiography, and/or conventional angiography; (3) presence of distal antegrade flow in the ipsilateral VA; and (4) absence of other causes of ischemic stroke. Of the 865 patients with PC stroke, 12 (1.4%) were diagnosed as having VA stump syndrome. The ischemic lesions included the cerebellum in all patients. Nine patients had multiple ischemic lesions in the brain stem, thalamus, or posterior lobe other than cerebellum. On duplex ultrasound, a to-and-fro flow pattern was observed in the culprit VA in 10 patients. Three patients had recurrences of ischemic stroke in the PC during the acute phase. VA stump syndrome was not a rare mechanism of PC stroke, and there was a high rate of stroke recurrence during the acute phase. Vascular assessment by a multimodality approach can be used to promptly detect VA stump syndrome.     

Ocular stroke and carotid artery dissection

Carotid artery dissection frequently causes transient ipsilateral visual impairment. We present 2 cases of permanent ocular vaso-occlusion sequelae consequent to dissection of the ipsilateral internal carotid, definite in one and probable in the other. In both, the ocular strokes led to the recognition of the underlying carotid vasculopathy.     

Efficacy of the stump pressure ratio as a guide to the safety of permanent occlusion of the internal carotid artery

Abstract

To determine whether the absolute value for the stump pressure might be a useful index of symmetrical cerebral blood flow (CBF), and to examine correlations with the stump pressure ratio (initial mean stump pressure,preocclusion mean arterial pressure), fifty candidates for ICA injury or permanent occlusion were evaluated preoperatively. Each was continuously monitored for mean stump pressure and arterial pressure before, during (for a total of 20 min), and after balloon test occlusion. During the occlusion, CBF was measured by 99m Tc-hexamethyl-propyleneamine oxime (99m Tc-HMPAO) single photon emission computed tomography (SPECT). The stump pressure and the stump pressure ratio were then compared with the results of 99m Tc-HMPAO SPECT. Patients who failed to tolerate even briefperiods ofcarotid occlusion and showed asymmetric decreases in CBF on SPECT were divided into high and moderate risk groups. Those with no significant changes in CBF on the occluded site formed the minimum risk group. Mean stump pressure was over 50 mmHg in 10 of a total of25 patients in the high and moderate risk groups, and below 50 mmHg in 5 of the 25 patients in the minimum risk group. The stump pressure ratio did not exceed 56% in any bu~ two patients in the high and moderate risk groups, and values were at least 60% in all patients of the minimum. risk group. Decrease ofCBF in two moderate risk group cases was localized in the posterior circulation. Difference in symmetrical CBF between the stump pressure ratio vs. the absolute value ofmean stump pressure were statistically significant (p < 0.01, Fisher,s Exact Test). Maintenance ofa stump pressure ratio of60% or more during test occlusion may be a more useful index for a good collateral circulation than any absolute value for mean stump pressure. [Neural Res 1998; 20: 732–736]     

前循环缺血性卒中老年患者颈动脉斑块及其稳定性与血流壁切应力的关系

目的通过探讨前循环缺血性卒中老年患者颈总动脉分叉处血流壁切应力的水平分析其在颈动脉斑块形成过程中的影响。方法本研究选择前循环缺血性卒中老年患者,应用经皮血管彩超测量颈动脉斑块及其稳定性以及对研究对象测量患侧颈动脉血流速度、血管内径和血液粘滞度,通过公式计算血流壁切应力。结果无斑块组和有斑块组之间、高回声和低回声斑块组之间血流壁切应力均有显著性差异(P<0．01)。结论血流壁低切应力促进颈动脉斑块、尤其是不稳定斑块的形成。     

颈动脉粥样硬化斑块与急性脑梗死患者血脂、血压关系的探讨

目的探讨急性脑梗死患者血脂浓度、血压与颈动脉粥样硬化斑块的关系。方法应用彩色多普勒超声检查急性脑梗死患者的颈动脉内膜-中膜厚度、斑块数和性状，同时检测血压。查血脂；121例急性脑梗死患者根据有无高血压分为脑梗死组47例、高血压并发脑梗死组74例，年龄相匹配的正常对照组35例。各项数据用SPSS10．0软件统计分析。结果脑梗死合并高血压组颈动脉粥样硬化斑块发生率最高（69．7％），且以软斑及混合斑为主，脑梗死组次之（59．6％），正常组最低（20％）。有颈动脉粥样硬化斑块与无颈动脉粥样硬化斑块相比．血清LDL—C水平明显升高。结论颈动脉粥样硬化斑决是脑梗死的重要危险因素，高血压及高LDL—C血症是颈动脉粥样硬化的危险因素．     

Common carotid arterial stiffness and the risk of ischaemic stroke

In the present case-control study we aimed to investigate the association of common carotid arterial (CCA) stiffness with ischaemic stroke (IS) and to determine whether this relationship was independent of conventional risk factors including CCA intima-media thickness (CCA-IMT). CCA distensibility, defined as the change of CCA-diameter during the cardiac cycle, and CCA-IMT were evaluated by means of high-resolution B-mode carotid ultrasound examination in consecutive, first-ever IS patients (n=193) and in age- and sex-matched control subjects (n=106). The CCA distensibility (inverse of CCA stiffness) was significantly (P=0.007) lower in IS (0.353 mm, 95% CI: 0.326-0.379) than in control subjects (0.415 mm, 95% CI: 0.378-0.451) even after adjusting for blood pressure values, diastolic CCA-diameter and height. The multivariate logistic regression procedure selected CCA-IMT and CCA distensibility as the only independent predictor variables of IS. Each 1 SD increase in the CCA-IMT and each 1 SD decrease in the CCA distensibility independently increased the likelihood of IS by 167.0% (OR: 2.67, 95% CI: 1.80-3.96, P<0.001) and 59.0% (OR: 1.59, 95% CI: 1.22-2.07, P=0.001) respectively. Increased CCA stiffness is associated with IS independent of conventional risk factors and CCA-IMT. The causal interrelationship between the elastic properties of the CCA and the risk of stroke deserves further investigation by longitudinal studies.     

Recurrent stroke: the role of common carotid artery intima-media thickness.

The etiology of recurrent stroke is probably multifactorial and many recurrences remain unexplained by conventional risk factors. The purpose of this study is to investigate if common carotid artery intima-media thickness (CCA-IMT), an established vascular risk factor, can predict recurrence in first-ever stroke survivors. Two hundred and eighty-four consecutive patients with a first-ever ischemic stroke were investigated with carotid ultrasonography and were screened for the first recurrent stroke up to 12 months. Sixteen (5.6%, 95% CI: 3.5-9.0%) recurrent ischemic strokes were recorded. Among demographic data, conventional vascular risk factors, presenting stroke features and ultrasonographic measurements, CCA-IMT was the only parameter that differed significantly between those who suffered a recurrent stroke and those who did not. Cox's regression analysis adjusted for confounding factors, showed that CCA-IMT was the only independent predictor of stroke recurrence (HR 1.65; 95% CI: 1.11-2.46%). We propose that CCA-IMT measurements may help to identify stroke patients at higher risk for recurrence and to plan secondary prevention strategies.     

Intravenous recombinant tissue plasminogen activator in acute carotid artery territory stroke.

To determine the effect of intravenous recombinant tissue plasminogen activator (rt-PA) on vascular and neurologic outcomes, we enrolled 31 patients with acute carotid artery-territory ischemic stroke within 6 hours from symptom onset in a randomized, double-blind, placebo-controlled study. We gave either rt-PA (duteplase at the dose of 20 or 30 mega-international units [MIU]) or placebo intravenously for 60 minutes in patients randomly assigned to the three groups. A comparison between the baseline and postinfusion angiograms showed that complete or partial reperfusion occurred in 50% (5/10) of patients treated with 30 MIU rt-PA, 44% (4/9) of those treated with 20 MIU rt-PA, and 17% (2/12) in the control group. In patients with middle cerebral artery occlusions, reperfusion occurred in 71% (5/7) of the 30-MIU group, in 67% (4/6) of the 20-MIU group, and in 13% (1/8) of the control group. Patients treated with 30 MIU rt-PA showed a significantly early and better clinical improvement, as measured by the neurologic scale, than did those treated with placebo. Parenchymal hemorrhage occurred in one patient in each group, and frequency of clinically insignificant hemorrhagic infarction was comparable among the treatment groups. No major systemic complications occurred in any group. These results support the efficacy of intravenous infusion of rt-PA soon after the onset of stroke in producing rapid thrombolysis and neurologic recovery; it may be of particular value in patients with thromboembolic occlusion in the middle cerebral artery.     

A new model of embolic stroke produced by photochemical injury to the carotid artery in the rat

We report a new model of embolic stroke in the rat, based on endothelial disruption and platelet aggregation in the carotid artery, which leads to distal embolization and focal brain infarction. The common carotid artery was irradiated for 6.5 minutes with the focused beam of an argon laser operated at a wavelength of 514.5 nm with a peak power of 2 W and an average power of 400 mw. Ipsilateral cerebral infarcts, ranging in size from 0.1 to 1.7 mm, were produced by platelet emboli in 12 of 13 rats. A total of 44 infarcts were observed in the 12 rats: 29 in the cortex, 6 in the hippocampus, 5 in the thalamus, and 4 in the basal ganglia. Scanning electron microscopy identified platelet aggregates in the carotid artery and in a deep cortical arteriole 50 minutes after the photochemical lesion. Twenty-four hours after the experiment, scanning electron microscopy of the carotid artery revealed damaged endothelium but few remaining adherent platelets. More intense laser irradiation in 8 rats, leading to carotid occlusion, produced an infarct in only 1. This new model can be used to study the acute and chronic pathological changes in the brain associated with platelet embolism.     

颈动脉超声对颈动脉狭窄及脑卒中高危人群的应用价值

目的探讨颈动脉狭窄及脑卒中高危人群中应用颈动脉超声的临床价值。方法选取2013-03—2013-09我院神经内科接收脑卒中康复治疗140例患者的资料进行分析,运用颈部血管超声检测颈动脉内中膜厚度(IMT)及斑块等。结果140例脑卒中高危人群中,超声检出颈动脉狭窄率75.1%,其中男性颈动脉内膜增厚占70.4%,颈动脉斑块阳性占80.3%;女性颈动脉增厚占59.4%,颈动脉斑块阳性占78.3%。颈动脉狭窄患者糖尿病、高血压、吸烟、饮酒及血脂程度高于正常患者。经Pearson相关分析发现颈动脉狭窄与脑卒中危险因素相关。结论颈动脉狭窄是脑血管病发病的危险因素,超声是探查颈动脉狭窄的有效手段。     

Local intrarterial thrombolysis for acute stroke in the carotid artery territories

We have tested the feasibility of local intraarterial thrombolytic therapy in ischemic stroke in the carotid artery territories observed within 5 h of the onset of symptoms. Only 5 of 615 consecutive patients were enrolled. They were 1 man and 4 women aged 50 to 75 years. Angiography disclosed occlusion of the M2 tract in one, of the M3 tract in one, of the carotid siphon in one of M4 tract in two. Intraarterial urokinase was infused at a mean dosage of 560,000 units close to the site of occlusion. Four of them had partial or complete recanalisation at early angiographic control and were independent at 6th month control. The one who did not demonstrate recanalisation was confined to a wheelchair. One patient, who had recanalisation, sustained a hemorrhagic transformation of the brain ischemia not interfering with outcome. Our experience, at the light of the low rate of enrollment, despite the results, suggest that intraarterial thrombolysis may be a therapeutic tool for selected patients with stroke in the carotid artery territories and not a routinary treatment for them.