ISSN:0039-2499    

出版商:OVID    

年代:1993

数据来源: OVID

摘要:

Background and PurposeCarotid endarterectomy has been shown to be beneficial in patients with high-grade carotid stenosis and ipsilateral transient ischemic attack or stroke. This benefit will be realized only if the operation is performed safely. We sought to determine the extent to which clinically significant adverse events occurring after carotid endarterectomy can be predicted from clinical data available before surgery.MethodsEleven hundred sixty patients were randomly selected from all patients who underwent carotid endarterectomy and were discharged during the calendar years 1988, 1989, and 1990 in 12 academic medical centers in 10 states. Clinical data abstracted from hospital charts were analyzed retrospectively. A model was developed and validated to predict the occurrence of stroke, myocardial infarction, or death during the postoperative period of hospitalization.ResultsEighty patients (6.9%) suffered at least one adverse event. Rates for individual complications were as follows: death, 1.4%; nonfatal stroke, 3.4%; nonfatal myocardial infarction, 2.1%; and nonfatal stroke or death, 4.8%. Significant predictors of adverse events were age 75 years or older, symptom status (ipsilateral symptoms versus asymptomatic or nonipsilateral symptoms), severe hypertension (preoperative diastolic blood pressure of greater than 110 mm Hg), carotid endarterectomy performed in preparation for coronary artery bypass surgery, history of angina, evidence of internal carotid artery thrombus, and internal carotid artery stenosis near the carotid siphon. The presence of two or more of these risk factors was associated with a nearly twofold increase in risk of an adverse event (relative risk, 1.7; 95% confidence interval, 1.0 to 3.0).ConclusionsClinical data can be used to stratify patients undergoing carotid endarterectomy according to risk of postoperative in-hospital stroke, myocardial infarction, or death.

ISSN:0039-2499    

出版商:OVID    

年代:1993

数据来源: OVID

摘要:

Background and PurposeData from recent multicenter carotid endarterectomy trials have questioned the validity and reliability of Doppler ultrasound in the assessment of carotid stenosis.MethodsWe prospectively analyzed 45 patients undergoing carotid angiography to compare the North American Symptomatic Carotid Endarterectomy Trial (NASCET) and European Carotid Surgery Trial (ECST) methods of measuring carotid stenosis with those of direct visualization (“eyeballing”) and duplex ultrasound. Linear NASCET and ECST measurements were also converted into area using the πr2function and termed “squared NASCET” (N2) and “squared ECST” (E2). In 15 of 45 patients undergoing carotid endarterectomy, the carotid plaque was removed intact, sectioned, and photographed for computer measurement of cross-sectional area. Comparison of this “gold standard” was then made to each method of measurement.ResultsComparison between duplex and the various angiographic measurement techniques revealed significant differences between NASCET and duplex (P<.0001), ECST and duplex (P<.01), and E2and duplex (P<.01) but not between N2eyeballing, and carotid duplex methods. Even the NASCET and ECST methods themselves differed significantly (P<.006). When comparison was made with computerized planimetric measurements of the carotid plaque, there were significant differences for both NASCET (P<.0007) and ECST (P<.007). Correlation was demonstrated only between planimetry and N2, E2, and duplex.ConclusionsNASCET and ECST angiographic methods of measurement consistently underestimate the “true” anatomic stenosis. As such, they represent only “indexes” of carotid stenosis severity. Duplex provides a more accurate measurement of carotid stenosis.

ISSN:0039-2499    

出版商:OVID    

年代:1993

数据来源: OVID

摘要:

Background and PurposeB-mode ultrasound is a widely used technique for the clinical and epidemiological assessment of carotid atherosclerosis. This article provides a description of the distribution of carotid atherosclerosis in the general population.MethodsIntimal-medial arterial wall thickness was measured by B-mode real-time ultrasound as an index of atherosclerotic involvement in the extracranial carotid arteries as part of the population-based Atherosclerosis Risk in Communities (ARIC) study. The distribution was described by race-sex strata, in which 759 to 4952 individuals were imaged depending on strata and location in the carotid system.ResultsMedian wall thickness ranged between 0.5 and 1 mm at all ages; fewer than 5% of ARIC participants had values exceeding 2 mm. Individuals tended to have a larger wall thickness in the carotid bifurcation than in the common carotid artery. Internal carotid artery values were more variable, with higher proportions of both large and small wall thicknesses than in the common carotid. The proportion of individuals with a large wall thickness was greatest at the bifurcation and smallest at the common carotid artery. Men had uniformly larger wall thickness than women. Cross-sectional analysis suggests that age-related increases in wall thickness average approximately 0.015 mm/y in women and 0.018 mm/y in men in the carotid bifurcation, 0.010 mm/y for women and 0.014 mm/y for men in the internal carotid artery, and 0.010 mm/y in both sexes in the common carotid artery.ConclusionsEstimates provided for wall thickness percentiles can serve as “nomograms” by age, race, and sex.

ISSN:0039-2499    

出版商:OVID    

年代:1993

数据来源: OVID

摘要:

Background and PurposeTranscranial color duplex sonographic examinations in children and adolescents without cerebrovascular disease were evaluated retrospectively. Flow velocities and waveform parameters were determined and their side-to-side differences and age dependence analyzed and, finally, compared with analogous data of a previously described group of healthy adults.MethodsWith a 2.0-MHz sector transducer of a computed sonographic system, the anterior, middle, and posterior cerebral arteries were examined in 64 children and adolescents between 1.5 and 17.5 years of age. Angle-corrected systolic peak, end-diastolic maximum, time-averaged, and time-averaged maximum velocities, and the resistance, pulsatility, and spectral broadening indexes were determined in all vessels.ResultsMean±SD values for time-averaged maximum velocity (and time-averaged velocity) were 92.2±13.0, 79.9±17.7, and 63.9±13.6 (55.3±11.7, 40.4±10.4, and 34.2±9.2) cm/s, respectively, in the middle, anterior, and posterior cerebral arteries in children under 10 years of age; values were 83.2 ±11.9, 69.4±13.8, and 55.6±10.1 (50.8±9.0,39.9±10.5, and 33.1±6.3) cm/s, respectively, in children 10 years of age and older. Time-averaged maximum velocity decreased significantly with age in all vessels (P<.001). Although time-averaged velocity did not change significantly during childhood and adolescence, a clear decline occurred from adolescence to adulthood (P<.0001 in the middle and posterior cerebral arteries;P<.01 in the anterior cerebral artery). The spectral broadening index decreased significantly from childhood to adolescence in the anterior and posterior cerebral arteries (P<.0001). The resistance and pulsatility indexes remained stable throughout childhood.ConclusionsTranscranial color duplex sonography allows angle-corrected measurements of “true” flow velocities in basal cerebral arteries. Additional determination of time-averaged velocity permits more detailed evaluation of flow characteristics for all age groups. The transcranial color duplex technique may provide deeper insights on normal cerebral perfusion and its disorders.

ISSN:0039-2499    

出版商:OVID    

年代:1993

数据来源: OVID

摘要:

Background and PurposeMagnetic resonance angiography is a new, noninvasive technique whose diagnostic value in vertebrobasilar artery disease has not yet been determined.MethodsForty-one patients with acute cerebellar and/or brain-stem ischemia were examined by routine magnetic resonance imaging, extracranial and transcranial Doppler ultrasound, and selective intraarterial arteriography. Results were correlated with magnetic resonance angiography. Magnetic resonance angiography was accomplished using a three-dimensional time-of-flight gradient-echo technique.ResultsMagnetic resonance angiography correctly identified all occlusions, stenoses, and an aneurysm within the distal vertebrobasilar system as revealed by conventional intra-arterial arteriography but missed the diagnosis of vertebral artery dissection in one case. This results in a sensitivity of magnetic resonance angiography of 97% and a specificity of 98.9%. However, the degree of stenoses was difficult to evaluate by magnetic resonance angiography. At least for severe obstructive lesions, this drawback can be eliminated by application of presaturation pulses, which allow the analysis of flow direction and collateral blood flow. Doppler ultrasound studies add useful hemodynamic information for less severe degrees of stenoses.ConclusionsThe combined use of magnetic resonance angiography and Doppler ultrasound findings may replace the invasive intra-arterial arteriography examination in many patients with suspected macroangiopathy of the vertebrobasilar arteries.

ISSN:0039-2499    

出版商:OVID    

年代:1993

数据来源: OVID

摘要:

Background and PurposeProton magnetic resonance spectroscopy has revealed changes in lactate and JV-acetyl-aspartate in acute cerebral infarction. However, the details of these drastic changes and subsequent chronic changes have not been clarified. The purpose of this study was to disclose longitudinal changes in spectra seen in proton magnetic resonance spectroscopy.MethodsSix patients with completed cerebral infarction were examined longitudinally with localized proton magnetic resonance spectroscopy.Results(1) In the acute stage (within 2 days after onset), two drastic changes were observed: JV-acetyl-aspartate decreased rapidly and severely within 2 days after onset, and lactate increased immediately and reached a high level in the acute stage after onset. (2) In the chronic stage (more than 1 month after onset), two features were observed: lactate, which had increased in the acute stage, remained high for more than 1 month, and other signals such as those ofN-acetyl-aspartate, choline, and phosphocreatine/creatine decreased dramatically.ConclusionsThese results suggest thatN-acetyl-aspartate and lactate as revealed by proton magnetic resonance spectroscopy can be useful indicators of the ischemic damage to the brain in clinical cases of cerebral infarction.

ISSN:0039-2499    

出版商:OVID    

年代:1993

数据来源: OVID

摘要:

Background and PurposeNew therapeutic interventions for acute ischemic stroke are aimed at improving cerebral blood flow in the first 3 to 6 hours after symptom onset. Single-photon emission-computed tomography (SPECT) performed in the setting of clinical therapeutic trials may give us a better understanding of the physiological response to new forms of treatment and could impact acute management decisions.MethodsWe prospectively studied 15 patients with hemispheric ischemic stroke with SPECT within 6 hours of symptom onset and again at 24 hours. The ischemic defect was assessed in a semiquantitative manner that used computer-generated regions of interest (SPECT graded scale). This measure was correlated with clinical presentation (National Institutes of Health [NIH] Stroke Scale), initial clinical course (change in NIH Stroke Scale), long-term outcome (Barthel Index at 3 months), and complications of cerebral hemorrhage and edema.ResultsThe severity of the SPECT graded scale on the admission scan correlated with the severity of neurological deficit (admission NIH Stroke Scale) (P<.05) and was positively associated with poor long-term outcome as measured with the Barthel Index (P<.001) and the complications of cerebral hemorrhage and massive cerebral edema (P<.005). In fact, there was a threshold value for the SPECT graded scale above which all patients suffered poor long-term outcome and the complications of cerebral hemorrhage and edema.ConclusionsThe measurement of an ischemic defect using SPECT is a valid assessment of hemispheric stroke severity in the hyperacute setting and may be useful for selecting or stratifying patients in clinical therapeutic trials.

ISSN:0039-2499    

出版商:OVID    

年代:1993

数据来源: OVID

摘要:

Background and PurposeThe aim of this study was to determine the potential value of carotid artery calcification observed on plain radiographs in patients referred for carotid angiogram in the diagnosis of carotid artery stenosis.MethodsOne hundred sixty consecutive patients with suspected carotid artery stenosis underwent both plain radiographs of the carotid arteries and digital subtraction angiography of the same vessels. In addition, 108 of these patients also had duplex ultrasound of the same vascular area. The clinical usefulness of the carotid artery calcification was assessed by calculating the likelihood ratios for different test results against results of angiography and duplex ultrasound.ResultsThere is a statistically significant association between the degrees of calcification and carotid disease as demonstrated by angiography (P=.0001), although positive correlation of the degrees of stenosis and calcification was only fair (Spearman correlation coefficientr=.4). The sensitivity of carotid calcification in detecting clinically significant stenosis assuming any calcification is abnormal was 89% with a specificity of 46%. The likelihood ratios for 50% stenosis by angiography varied from 0.24 (no calcification) to 3.41 (level III) and for 50% stenosis by duplex ultrasound varied from 0.21 (no calcification) to more than 5.87 (level III). Assessments of the degree of calcification based on plain radiographs had excellent reproducibility (all intraclass correlation coefficients were greater than .9).ConclusionsIn this population with a high prevalence of carotid artery disease, there is an association between the presence of carotid calcification and atheromatous disease. If subsequent studies were to show this to apply in the general population, this could be of value in identifying asymptomatic patients at increased risk.

ISSN:0039-2499    

出版商:OVID    

年代:1993

数据来源: OVID

摘要:

Background and PurposeA recent transcranial Doppler study found reduced blood velocity in seven patients during migraine attacks in the middle cerebral artery at the headache side. This would implicate vasodilation of the middle cerebral artery in the pathogenesis of headache in migraine. We attempted to confirm this finding.MethodsWe determined blood velocity with transcranial Doppler ultrasonography in the middle cerebral arteries of 51 migraine patients with unilateral headache (5 with aura, 46 without aura) and of 14 patients with bilateral headache, during and outside attacks. During attacks, median time from onset of attack to transcranial Doppler examination was 6 hours (range, 1 to 35 hours).ResultsWe found no difference between blood velocity at the headache and nonheadache sides nor between blood velocity during and outside attacks. Similar results were obtained in a subgroup of 11 patients who were investigated in the first 4 hours of an attack. There were also no differences between attacks with unilateral or bilateral headache.ConclusionsWe cannot support the hypothesis that migraine is associated with vasodilation of the middle cerebral artery ipsilateral to the headache.

ISSN:0039-2499    

出版商:OVID    

年代:1993

数据来源: OVID