Showing papers on "Stenosis published in 1996"

Apolipoproteins B, (a), and E Accumulate in the Morphologically Early Lesion of ‘Degenerative’ Valvular Aortic Stenosis

Abstract: Nonrheumatic aortic stenosis of trileaflet aortic valves has been considered to be a "degenerative" process, but the early lesion of aortic stenosis contains the chronic inflammatory cells, macrophages and T lymphocytes. Because lipoprotein deposition is prominent in atherosclerosis, another chronic inflammatory process, this study examined whether lipoproteins accumulate in aortic valve lesions. Immunohistochemical studies were performed to detect apolipoprotein (apo) B, apo(a), apoE, macrophages, and alpha-actin-expressing cells on 18 trileaflet aortic valves that ranged from normal to stenotic. All three apolipoproteins were detected in early through end-stage lesions of aortic stenosis but not in histologically normal regions. Comparison with oil red O staining suggested that most of the extracellular neutral lipid in these valves was associated with either plasma-derived or locally produced apolipoproteins. Thus, in early through end-stage aortic valve lesions, apolipoproteins accumulate and are associated with the majority of extracellular valve lipid. These results are consistent with the hypothesis that lipoprotein accumulation in the aortic valve contributes to pathogenesis of aortic stenosis.

Race and Sex Differences in the Distribution of Cerebral Atherosclerosis

Abstract: Background and Purpose The purpose of this study was to assess the influence of race, sex, and other risk factors on the location of atherosclerotic occlusive lesions in cerebral vessels. Previous angiographic studies of patients with stroke or transient ischemic attack (TIA) suggest that extracranial atherosclerosis is more common in whites and intracranial disease is more common in blacks. Noninvasive techniques such as duplex ultrasound, transcranial Doppler (TCD), and magnetic resonance angiography (MRA) allow vascular assessment of a more representative proportion of patients than does conventional angiography alone. Methods Consecutive patients evaluated at a community hospital for stroke or TIA over a 2-year period were reviewed. Lesions were defined as a 50% or greater atherosclerotic stenosis by angiography, duplex ultrasound, or TCD, or a moderate stenosis by MRA. Results Whites were more likely than blacks to have extracranial carotid artery lesions (33% versus 15%, P=.001), but the proportion ...

Carotid artery stenosis: treatment with protected balloon angioplasty and stent placement.

Abstract: PURPOSE: To assess effectiveness of endovascular treatment of carotid artery stenosis by means of angioplasty with cerebral protection and stent placement. MATERIALS AND METHODS: Angioplasty was performed for carotid artery stenosis in 259 patients. Cerebral protection (triple coaxial catheter) was used in 136 cases of atherosclerotic stenosis in the internal carotid artery or in the carotid bifurcation and was not used in 123 cases. A stent was placed in 69 patients when images obtained immediately after angioplasty showed signs of dissection or insufficient arterial opening. RESULTS: No procedure-related complications occurred in the 71 cases of nonatherosclerotic stenosis and in the 14 cases of proximal carotid artery and siphon atherosclerotic stenosis. Among the 38 patients who underwent angioplasty without cerebral protection, dissection occurred in two (5%) and embolic complication occurred in three (8%) during the procedure. Among 136 patients in whom cerebral protection was used, no embolic compl...

An Assessment of Surgery for Spinal Stenosis: Time Trends, Geographic Variations, Complications, and Reoperations

Abstract: OBJECTIVE: To study temporal trends and geographic variations in the use of surgery for spinal stenosis, estimate short-term morbidity and mortality of the procedure, and examine the likelihood of repeat back surgery after surgical repair. DESIGN: Cohort study based on Medicare claims. SETTING: Hospital care. SUBJECTS: All Medicare beneficiaries 65 years of age or older who received a lumbar spine operation for spinal stenosis in 1985 or 1989 were followed through 1991 (10,260 patients from the 1985 cohort and 18,655 from the 1989 cohort). MAIN OUTCOME MEASURES: Two outcomes were measured: (1) rates of operation for spinal stenosis by state and (2) on an individual level, operative complications (cardiopulmonary, vascular, or infectious), postoperative mortality, and time between first operation and any subsequent reoperation. RESULTS: Rates of surgery for spinal stenosis increased eightfold from 1979 to 1992 for patients aged 65 and older and varied almost fivefold among US states. Mortality and operative complications increased with age and comorbidity. Complications were more likely for men and for individuals receiving spinal fusions. The 1989 cohort experienced a slightly higher probability of reoperation than the 1985 cohort for the first 3 years of follow-up. CONCLUSIONS: A rapid increase in surgery rates for spinal stenosis was identified over a 14-year period. The wide geographic variations and substantial complication rate from this elective surgical procedure (partly related to patient age) suggest a need for more information on the relative efficacy of surgical and nonsurgical treatments for this condition. The risks and benefits of particular surgical procedures for specific clinical and demographic subgroups as well as individual patient preferences regarding surgical risks and possible outcomes should also be evaluated further. These issues are likely to become increasingly important with the aging of the US population. J Am Geriatr Soc 44:285–290, 1996.

Molecular Mechanisms of Coronary Collateral Vessel Growth

Abstract: Growth of coronary collaterals can change markedly the natural history of coronary artery disease: Stenoses and occlusions of the coronary arteries, even of the left main coronary artery, can be survived without infarction provided that the stenosing process has not progressed too fast, since the process of collateral development by growth needs time (a few weeks).1 2 3 However, in most cases, thrombus formation proceeds faster than vascular growth and infarcts develop. In many cases, collaterals, although they cannot prevent infarction in the majority of cases, may limit the damage and infarcts are smaller than expected from the size of the region at risk.4 Understanding collateral growth may mean to be potentially and eventually able to stimulate it by the injection of drugs, by the injection of growth factors, or by somatic gene therapy in patients at risk of infarction. In the past we have shown that collaterals grow by DNA synthesis and mitosis of endothelial and smooth muscle cells.3 These cells are quiescent in normal adult arteries, with their population kinetics close to zero. Under abnormal conditions a rapid conversion to G1 can occur and the cell cycle can be completed in ≈22 hours.3 With rapidly progressing stenosis in dogs (3 days from the onset of stenosis to complete occlusion), the labeling index of the endothelium of the midzone segment reached 7.5% and was followed by a wave of smooth muscle cell mitosis of only slightly lesser magnitude. Since controlled and regulated growth does not proceed without the presence and action of growth factor peptides and their receptors, several groups have investigated that aspect.5 6 7 8 The growth factors that are potentially involved in the process of cardiac collateralization are aFGF, bFGF, VEGF, IGF-1, and PDGF.7 9 10 11 12 13 …

Spinal stenosis and neurogenic claudication.

Abstract: Neurogenic claudication is diagnosed from a classical history and complementary spinal imaging. The abnormal signs may be few. It should be distinguished from intermittent claudication (peripheral vascular disease), referred pain from the back or root pain that is aggravated by walking, and psychological distress. Pathologically, a developmentally small canal is usually affected by multiple levels of segmental degenerative change, with venous pooling in the cauda equina between two levels of low pressure stenosis. There is probably then a failure of arterial vasodilatation of the congested roots in response to exercise, with symptoms in the legs when walking. Once established, symptoms tend neither to improve nor deteriorate. Conservative management is reasonable. Otherwise decompression at the most significant stenotic level is probably adequate to obtain a good surgical result.

Measurement properties of a self-administered outcome measure in lumbar spinal stenosis.

Abstract: Study design The measurement properties and validity of a newly developed patient questionnaire for the assessment of patients with lumbar spinal stenosis was tested in an ongoing prospective multicenter observational study of patients undergoing decompressive surgery in three teaching hospitals. Objective The goal of the study was to develop a short, self-administered questionnaire on symptom severity, physical functional status, and patient satisfaction. Summary of background data The measure is intended to complement existing generic measures of spinal-related disability and health status. The questionnaire includes three scales with seven questions on symptom severity, five on physical function, and six on satisfaction. Methods The internal consistency of the scales was assessed with Cronbach's coefficient alpha on cross-sectional data from 193 patients before surgery. The test-retest reliability was assessed on data from a random sample of 23 patients using Spearman's rank correlation coefficient. The responsiveness was assessed on 130 patients with 6-month follow-up data using the standardized response mean. Results The test-retest reliability of the scales ranged from 0.82 to 0.96, the internal consistency from 0.64 to 0.92, and the responsiveness from 0.96 to 1.07. The direction, statistical significance, and strength of hypothesized relationships with external criteria were as expected. Conclusions This short self-administered spinal stenosis measure is reproducible, internally consistent, valid, and highly responsive. It can be used to complement generic instruments in outcome assessment of patients with lumbar spinal stenosis.

The Maine Lumbar Spine Study, Part III. 1-year outcomes of surgical and nonsurgical management of lumbar spinal stenosis.

Abstract: Study design A prospective cohort study of patients with lumbar spinal stenosis recruited from the practices of orthopedic surgeons and neurosurgeons throughout Maine. Objective To assess 1-year outcomes of patients with lumbar spinal stenosis treated surgically or nonsurgically. Summary of background data No randomized trials and few nonexperimental studies have compared surgical and nonsurgical treatment of patients with lumbar spinal stenosis. The authors' goal was to assess 1-year outcomes of patients with lumbar spinal stenosis treated surgically or nonsurgically. Methods Eligible, consenting patients participated in baseline interviews and were then mailed follow-up questionnaires at 3, 6, and 12 months. Clinical data were obtained from a physician questionnaire. Outcomes included patient-reported symptoms of leg and back pain, functional status, disability, and satisfaction with care. Results One hundred forty-eight patients with lumbar spinal stenosis were enrolled, of whom 81 were treated surgically and 67 treated nonsurgically. On average, patients in the surgical group had more severe imaging findings and symptoms and worse functional status than patients in the nonsurgical group at entry. Few patients with mild symptoms were treated surgically, and few patients with severe symptoms were treated nonsurgically. However, of the patients with moderate symptoms, a similar percent were treated surgically or nonsurgically. One year after study entry, 28% of nonsurgically and 55% of surgically treated patients reported definite improvement in their predominant symptoms (P = 0.003). For patients with moderate symptoms, outcomes for surgically treated patients were also improved compared with those of nonsurgically treated patients. Surgical treatment remained a significant determinant of 1-year outcome, even after adjustment for differences between treatment groups at entry (P = 0.05). The maximal benefit of surgery was observed by the time of the first follow-up evaluation, which was at 3 months. Although few nonsurgically treated patients experienced a worsening of their condition, there was little improvement in symptoms and functional status compared with study entry. Conclusions At a 1-year evaluation of patient-reported outcomes, patients with severe lumbar spinal stenosis who were treated surgically had greater improvement than patients treated nonsurgically. Comparisons of outcomes by treatment received must be made cautiously because of differences in baseline characteristics. A determination of whether the outcomes observed persist requires long-term follow-up.

Angioplasty and Stenting for Restenosis After Carotid Endarterectomy Initial Experience

Abstract: Background and Purpose Endarterectomy for recurrent carotid stenosis after endarterectomy has a significantly higher complication rate than the original operation Angioplasty and stenting may offer a useful alternative treatment for these patients Methods Between September 1994 and April 1996, 22 patients had 25 carotid arteries treated with angioplasty and stenting for postendarterectomy restenosis All patients had an independent neurological examination and National Institutes of Health Stroke Scale evaluation before and after the procedure Patients were treated with aspirin and ticlopidine All patients were requested to return at 6 months for follow-up angiography The mean patient age was 69±7 years, and the mean elapsed time from endarterectomy was 73±69 months Seventy-seven percent of the patients were symptomatic Results Mean stenosis was reduced from 79±13% before the procedure to 18±36% after stenting One patient had a minor stroke, for a complication rate of 4% per treated artery In the eight patients who returned for 6-month angiography, mean stenosis was 194±44% and restenosis (≥50% stenosis) did not occur Conclusions In a small series, angioplasty and stenting appear to be safe and well tolerated for the treatment of postendarterectomy restenosis

Remodeling rather than neointimal formation explains luminal narrowing after deep vessel wall injury: insights from a porcine coronary (re)stenosis model.

Abstract: Background Oversized balloon dilatation of normal porcine coronary arteries usually heals without stenosis formation Methods and Results With the purpose of developing a stenotic model and examining the mechanisms of luminal narrowing after angioplasty, we produced a circumferential deep vessel wall injury by inflating and withdrawing an oversized chain-encircled angioplasty balloon in the left anterior descending coronary artery (LAD) of 20 pigs Three pigs died and did not complete the study In 8 pigs (group 1), serial coronary arteriography was performed The lumen diameter (mean±SD) before dilatation was 34±04 mm; after dilatation, 42±06 mm; and at follow-ups 2 and 4 weeks later, 16±04 mm (P<0001) In 9 pigs (group 2) examined postmortem 3 weeks after dilatation, histology revealed that the injury was deep (out to adventitia) in all arteries and completely circumferential (360°) in all but two arteries Adventitia was markedly thickened as a result of neoadventitial formation Injury correlat

Clinical outcomes and radiological instability following decompressive lumbar laminectomy for degenerative spinal stenosis: a comparison of patients undergoing concomitant arthrodesis versus decompression alone.

Abstract: ✓ One hundred twenty-four patients with degenerative lumbar stenosis underwent decompression with fusion (32 patients) and without fusion (92 patients) during a 30-month period between 1986 and 1988. Patient-reported satisfaction at a mean follow-up period of 5.8 years (range 4.6–6.8 years) revealed a 79% good or fair outcome and a 21% poor outcome (26 patients). Seven patients (6%) developed lumbar instability, three patients (2%) developed new stenosis at an adjacent unoperated level, and three patients (2%) developed a new disc herniation between 2 and 5 years after surgery. Progressive postoperative spondylolisthesis occurred in 31% of patients with normal preoperative alignment (mean 7.8 mm, range 2–20 mm) and in 73% of patients with preoperative subluxation (mean 5.1 mm, range 2–13 mm) in whom fusion was not attained. Radiological progression did not correlate well with patient-reported outcome. The major conclusions from this study are the following: 1) the majority of patients respond well to this...

Transforaminal arthroscopic decompression of lateral recess stenosis

Abstract: ✓ The purpose of this study was to evaluate the feasibility and efficacy of arthroscopic decompression of lateral recess stenosis, determine potential associated complications, and present an alternative method to access the lateral recess of the lumbar spine. Forty patients were selected in whom the authors found clinical and computerized tomography evidence of lateral recess stenosis and sequestered foraminal herniations. All 40 were treated with a posterolateral arthroscopic technique, and 38 were available for this follow-up evaluation. A satisfactory result was obtained in 31 patients (82%). No neurovascular complications were encountered; however, other complications included an infection of the disc space in one patient and a causalgic-type pain in the involved extremity in four patients. The associated postoperative morbidity in this group of patients was minimal and resulted in rapid rehabilitation and return of patients to preoperative functioning level.

Intracoronary irradiation: Dose response for the prevention of restenosis in swine

Abstract: Purpose:Restenosis after percutaneous transluminal coronary angioplasty represents, in part, a proliferative response of vascular smooth muscle at teh site of injury. We have previously shown that high-dose radiation (20 Gy), delivered via an intracoronary 192Ir source, causes focal medial fibrosis and markedly impairs the restenosis process after balloon angioplasty in swine. This study sought to delineate the dose-response characteristics of this effect. Methods and Materials: Forty juvenile swine underwent coronary angiography; a segment of the left coronary artery was chosen as a target for balloon injury. In 30 swine, a 2 cm ribbon of 192Ir was positioned at the target segment and 20, 15, or 10 Gy were delivered to the vessel wall (10 animals/dose). Subsequently, overdilatation balloon angioplasty was performed at the irradiated segment. In 10 control swine, overdilatation balloon angioplasty was performed without previous irradation. Thirty-eight animals survived until sacrifice at 30 ± 3 days. Histopathological analysis was performed by a pathologist in a blinded manner. The area of maximal luminal compromise within the target segment was analyzed via computer-assisted planimetry. Results: Neointimal area was decreased by 71.4% at 20 Gy and by 58.3% at 15 Gy compared with control animals (p < 0.05). A stimulatory effect on smooth muscle cell proliferation was noted at 10 Gy, with a 123% increase in neointimal area compared with controls (p < 0.05). Mean percent area stenosis was also reduced by 63% at 20 Gy and by 74.8% at 15 Gy compared with controls (p < 0.05 for both). Conclusions: Intracoronary irradiation prior to overstretch balloon angioplasty markedly reduces neointima formation: this effect is dose dependent, with evidence of a significant stimulatory effect at 10 Gy. The effective therapeutic dose range for the prevention of restenosis in this in this model begins at approximatley 15 Gy delivered to the vessel wall.

Prevalence and Predictors of Atrial Fibrillation in Rheumatic Valvular Heart Disease

Abstract: The highest frequency of AF in RHD occurs in those with mitral stenosis, mitral regurgitation, and tricuspid regurgitation in combination. AF, while occurring in 29% of patients with isolated mitral stenosis and in 16% with isolated mitral regurgitation, is an infrequent finding (1%) in patients with aortic valvular disease. Left atrial diameter by univariate analysis, and age and left atrial diameter by multivariate analysis have been shown to be the most important parameters to determine the occurrence of AF in patients with RHD.

Aortic atheromas and acute ischemic stroke: A transesophageal echocardiographic study in an ethnically mixed population

Abstract: Purpose: Proximal aortic atheromas have been suggested as a potential ischemic stroke determinant in the elderly, especially in cases of unexplained (cryptogenic) stroke Our aim was to assess the potential role of proximal aortic atheromas as an independent risk factor for stroke by comparing their frequency in patients with acute ischemic stroke and in stroke-free control subjects The frequency of atheromas was also compared among different ethnic groups Patients and Methods: A case-control study was conducted in 106 patients with acute ischemic stroke and 114 stroke-free control subjects The presence of atheromas of the proximal portion of the aorta was assessed by biplane transesophageal echocardiography Atheromas were categorized on the basis of their thickness (02 to 04 cm, small; >or=to05 cm, large) and complexity (ie, ulceration or mobility) The association between aortic atheromas and ischemic stroke was tested, controlling for patients9 demographic variables and stroke risk factors In stroke patients, subgroup analyses were performed to test the associations between aortic atheromas and stroke diagnostic subtypes (determined cause versus cryptogenic) and presence and degree of carotid stenoses by duplex Doppler examination Results: The frequency of large aortic atheromas was greater in stroke patients than in controls (26% versus 13%; crude odds ratio [OR] 24, 95% CI 12 to 47); ulcerated or mobile atheromas also tended to be more frequent in stroke patients (12% versus 5%; OR 25, 95% CI 10 to 68) Differences were entirely attributable to the subgroup of patients aged 60 years or older, in whom the frequency of ulcerated or mobile atheromas was particularly high among cryptogenic stroke patients (22% versus 8% in control subjects; OR 34, 95% CI 11 to 112) Multivariate analysis showed the presence of large atheromas to be independently associated with stroke in the entire study group (adjusted OR 26, 95% CI 11 to 59) and in the older subgroup (OR 24, 95% CI 11 to 57) Carotid stenosis >or=to 60% was more frequent with increasing size and complexity of aortic atheromas but had low predictive value (16%) for presence of large atheromas; moreover, 36% of patients with mild or no carotid stenosis had large or complex aortic atheromas No significant differences were found in the frequency of atheromas by ethnic group Conclusions: Proximal aortic atheromas >or=to 05 cm in size are a risk factor for ischemic stroke in patients aged 60 years or older Ulcerated or mobile atheromas may play a role in explaining some cryptogenic strokes in the elderly The risk for stroke of patients with aortic atheromas may be similar across different ethnic groups The absence of carotid stenosis does not exclude aortic atheromas as a potential cause for ischemic stroke NEUROLOGY 1996;46: 1560-1566

A Systematic Comparison of the Risks of Stroke and Death Due to Carotid Endarterectomy for Symptomatic and Asymptomatic Stenosis

Abstract: Background and Purpose There is some evidence that carotid endarterectomy reduces the risk of ipsilateral carotid territory ischemic stroke in patients with severe asymptomatic carotid stenosis. However, the benefit of endarterectomy is dependent on a low risk of stroke and/or death due to surgery. Whether the low operative risks reported in recent clinical trials and cited in recent guidelines are widely generalizable to clinical practice is unclear. Is endarterectomy for asymptomatic carotid stenosis really safer than surgery for recently symptomatic stenosis? Methods We performed a systematic review comparing the risks of stroke and death due to carotid endarterectomy, performed by the same surgeons or in the same institutions, for symptomatic and asymptomatic stenosis in studies published since 1980. Results Twenty-five studies fulfilled our criteria. Mortality within 30 days of endarterectomy was 1.31% for asymptomatic stenosis and 1.81% for symptomatic stenosis (odds ratio [OR], 0.69; 95% confidence...

Assessment of coronary artery stenosis by magnetic resonance imaging.

Abstract: OBJECTIVE: The findings of magnetic resonance and x-ray angiography were compared for assessment of coronary artery stenosis in this validation study. BACKGROUND: Magnetic resonance angiography of the coronary arteries has recently been described, but there has been no comparison with x-ray angiography of localisation or assessment of important characteristics of coronary stenosis. METHODS: A breath hold, segmented k-space, 2D gradient echo imaging technique incorporating fat suppression was used in 39 patients (55 coronary stenoses) with known coronary artery disease. RESULTS: Overall, 47 stenoses (85%) were assessed by magnetic resonance (29 of 33 stenoses in the left anterior descending artery, one of one in the left main stem, 14 of 17 in the right coronary artery, and three of four in the left circumflex artery were detected). There was close agreement between magnetic resonance and x-ray angiography for the distance of the stenosis from the arterial origin (magnetic resonance mean (SD) 27 (16) mm versus x-ray angiography 27 (16) mm, P = NS, mean difference -0.2 mm). The distance to 39 stenoses (83%) agreed to within 5 mm, with increased scatter for more distal stenoses. The severity of magnetic resonance signal loss, assessed visually at the site of stenosis, varied significantly according to the percentage diameter stenosis (F = 30, P < 0.0001); stenosis severity with severe signal loss was 89 (7)%, with partial signal was 70 (16)%, and with irregular wall only 37 (11)%, with significant differences among the three groups (P < 0.001). A significant correlation was found between the proportional magnetic resonance signal loss at the stenosis and the percentage diameter stenosis severity (r = -0.67, P < 0.0001). The length of stenosis measured by magnetic resonance (6 (3) mm) was greater than by x-ray angiography (5 (2) mm, P < 0.006, mean difference +1.1 mm). Spearman's rank test showed that there was significant overestimation of stenosis length by magnetic resonance as stenosis severity increased (rs = 0.34, P < 0.02). CONCLUSIONS: Accurate localisation of coronary stenosis and a qualitative assessment of stenosis severity are possible by magnetic resonance, but stenosis length is overestimated as severity increases, probably because of disturbed patterns of flow with turbulence distal to severe stenoses. Reasonable results for the detection of coronary artery stenosis by magnetic resonance were achieved in this highly selected population, but further progress in imaging techniques is necessary before moving towards appreciable clinical application.

Angiographic and duplex grading of internal carotid stenosis: can we overcome the confusion?

Abstract: The stroke risk reduction benefit of surgical intervention in carotid occlusive disease has been validated in multicenter trials for various angiographically defined lesion severity categories. The two divergent angiographic grading methods used for internal carotid artery stenosis in these trials have caused confusion in the clinical application of their recommendations. Moreover, while today's highly accurate carotid duplex scanning can obviate the need for preoperative angiography in many cases, the duplex criteria must be tailored to achieve sufficiently reliable results on which therapeutic decisions can be made. This review offers a clarification of the discrepancies between the angiographic grading techniques and how their measurements of percent stenosis correlate to the duplex criteria needed to support the treatment decision-making process for carotid obliterative disease.

Natural history of aortic valve stenosis of varying severity in the elderly

Abstract: In a population sample of 501 persons aged 75 to 86 years, Doppler echocardiography uncovered moderate or severe aortic valve stenosis in 8.8% of women and 3.6% of men. Severe aortic valve stenosis predicted a four-fold-age- and sex-adjusted risk of death within 4 years of diagnosis, and mortality tended to be increased also with moderate lesions; mild aortic valve stenosis had a favorable outcome.

Is Impaired Cerebral Vasomotor Reactivity a Predictive Factor of Stroke in Asymptomatic Patients

Abstract: Background and Purpose Identification of the subgroup of asymptomatic patients with severe internal carotid artery stenosis and high risk of stroke has important clinical implications. Cerebral vasomotor reactivity provides information regarding intracranial hemodynamic features and might have a prognostic value in predicting cerebrovascular ischemic events, especially in patients with carotid stenosis. The aim of our study was to assess the cerebral vasomotor reactivity in asymptomatic patients with carotid stenosis and evaluate its role in stroke occurrence. Methods Cerebral vasomotor reactivity was assessed using transcranial Doppler ultrasonology and the Diamox test (intravenous administration of 1.0 g acetazolamide) in 44 asymptomatic patients with severe (>70%) internal carotid artery stenosis. Patients were followed up prospectively (mean, 2 years). Results Cerebral vasomotor reactivity was estimated as good (>40% increase of blood flow velocity in the middle cerebral artery ipsilateral to the caro...