Biomedical subjects
Publications and source records attributed to L Nelson Hopkins.
Recent advances have furthered our understanding of changes in CBF after ICH. Recent evidence from experimental and clinical studies has not supported the role of CBF changes in the pathogenesis of neuronal injury. A better understanding of these changes in ICH has modified the basis for formulating treatment strategies and developing innovative therapies.
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OBJECTIVE: To study regional intraparenchymal pressures within the cranial cavity during and after formation of intracerebral hemorrhage. We also assessed the effect of hypertonic saline on intraparenchymal pressure in different brain regions and on regional brain distribution of sodium within the brain. DESIGN: Prospective, controlled, laboratory trial. SETTINGS: Animal research laboratory. SUBJECTS: Eight mongrel dogs, weighing 15-25 kg. INTERVENTION: We introduced an intracerebral hematoma in eight mongrel dogs by infusing 6 mL of autologous arterial blood in the deep white matter adjacent to the basal ganglia. Sodium chloride (23.4%, 1.4 mL/kg) then was administered intravenously 6 hrs after introduction of hematoma. MEASUREMENTS AND MAIN RESULTS: Parenchymal pressure monitors were placed in the perihematoma region, both frontal lobes, and the cerebellum to record intraparenchymal pressure during and 6 hrs after intracerebral hematoma formation. Intraparenchymal pressure measurements were recorded for 3 more hours after administration of 23.4% sodium chloride. Regional cerebral perfusion pressure was calculated for each intraparenchymal pressure measurement. Regional sodium distribution was measured in extracts from brain regions by using ion selective electrode technique. A higher elevation in intraparenchymal pressure was recorded in the perihematoma region during the introduction of the hematoma compared with other compartments. After 5 mL of autologous blood was introduced, intraparenchymal pressure (mm Hg +/- SE) was significantly higher in the perihematoma region (42.1 +/- 3.5) than in the ipsilateral (30.0 +/- 4.6, p <.05) and contralateral (27.1 +/- 5.5, p <.01) frontal lobes and cerebellum (29.1 +/- 4.5, p <.05). Four hours after introduction of the hematoma, the cerebral perfusion pressure recorded in the perihematoma region (43.6 +/- 9.7) remained significantly lower than in the ipsilateral (58.6 +/- 9.3, p <.05) but not the contralateral frontal lobes (54.7 +/- 10.1) and cerebellum (51.0 +/- 11.1). Administration of 23.4% sodium chloride immediately reduced intraparenchymal pressure in each compartment. This effect was still observed at 3 hrs in each compartment. Sodium concentration was higher in the perihematoma region than in the frontal lobes, cerebellum, or brain stem. CONCLUSIONS: Prominent differences were observed in intraparenchymal pressure and cerebral perfusion pressure in the perihematoma region and frontal lobes during and after intracerebral hematoma. We speculate that the potential importance of regional intraparenchymal pressure differences in the clinical settings may be under appreciated. In this canine model of intracerebral hematoma, a single dose of hypertonic saline effectively reduces the intraparenchymal pressure in all regions of the brain.
OBJECTIVE: To determine the frequency of perioperative complications since the introduction of abciximab, we prospectively evaluated our experience in a consecutive series of patients undergoing carotid angioplasty and stent placement (CAS). CAS has been introduced recently for treatment of carotid artery stenosis. A major limitation to this modality is the risk of perioperative thromboembolic and ischemic events. To reduce the risk of ischemic complications, abciximab, a platelet glycoprotein IIb/IIIa receptor inhibitor, has been introduced as adjunctive treatment for high-risk patients. METHODS: Each patient was evaluated by a neurologist before, immediately after, and 24 hours after CAS for identification and classification of new neurological deficits. Bleeding events or other complications during hospitalization were recorded. Bleeding complications were classified as major (hemoglobin decrease,g5 g/dl), minor (hemoglobin decrease, 3-5 g/dl), or insignificant. Abciximab was administered intravenously as a single bolus (0.25 mg/kg) and then via infusion (10 microg/min) for 12 hours as an adjunct to CAS in patients considered to be at high risk for thromboembolic events owing to recent ischemic symptoms and/or complex lesion morphology. RESULTS: Intravenously administered abciximab was used in 37 patients (mean age, 70 yr; 21 patients were men) as an adjunct to high-risk CAS. Thirty-three other patients underwent CAS performed with standard intraprocedural heparinization (mean age, 69 yr; 17 patients were men). Minor ischemic strokes were observed in 1 of 37 abciximab-treated patients and in 4 of 33 heparin-treated patients. No major ischemic strokes were observed in either group. Transient neurological deficits were observed in nine patients in the abciximab-treated group and in one patient in the heparin-treated group. Transient neurological deficits in abciximab-treated patients were mainly related to hemodynamic factors (associated with balloon inflation in two patients and with hypotension in another two patients) or occurred after completion of infusion (in three patients). Minor bleeding complications were observed in three patients who received abciximab and in four patients who received standard heparinization. Major bleeding complications were observed in four patients from each group. Two patients who received abciximab developed intracerebral hemorrhages; one hemorrhage was fatal. CONCLUSION: The frequency of ischemic stroke in high-risk patients (3%) with the use of intravenously administered abciximab was lower, but not significantly so, than rates observed in lower-risk patients (12%), although the benefit was lost because of the high rate of intracranial hemorrhages (5%). Further efforts are required to determine appropriate selection criteria for use of intravenously administered abciximab and the effect of other strategies that involve distal protection devices.
OBJECTIVE: Abnormal serum sodium levels (hyponatremia and hypernatremia) are frequently observed during the acute period after aneurysmal subarachnoid hemorrhage (SAH) and may worsen cerebral edema and mass effect. We performed this study to determine the prognostic significance of serum sodium concentration abnormalities. METHODS: We analyzed prospectively collected data for the placebo treatment group in a clinical trial conducted at 54 neurosurgical centers in North America. The presence of hypernatremia (serum sodium concentration of >145 mmol/L) and hyponatremia (serum sodium concentration of <135 mmol/L) was determined with serum sodium measurements obtained at admission and 3, 6, and 9 days after SAH. The effects of hypernatremia and hyponatremia on the risk of symptomatic vasospasm and on 3-month outcomes were analyzed after adjustment for the following potential confounding factors: age, sex, preexisting hypertension, admission Glasgow Coma Scale score, initial mean arterial pressure, subarachnoid clot thickness, intraventricular blood or intraparenchymal hematoma, ventricular dilation, and aneurysm size and location. RESULTS: Of 298 patients in the analysis, 58 (19%) developed hypernatremia and 88 (30%) developed hyponatremia. Hypernatremia was significantly associated with poor outcomes (odds ratio, 2.7; 95% confidence interval, 1.2-6.1). A positive correlation was observed between the highest sodium values recorded and Glasgow Outcome Scale scores at 3 months (P < 0.0001 by analysis of variance). Hyponatremia was not associated with 3-month outcomes (odds ratio, 1.9; 95% confidence interval, 0.9-4.3). Neither hypernatremia nor hyponatremia was associated with the risk of symptomatic vasospasm. CONCLUSION: Hyponatremia seems to be more common than hypernatremia after SAH. However, hypernatremia after SAH is independently associated with poor outcomes, and this association is independent of previously identified outcome predictors, including age and admission Glasgow Coma Scale scores. Further studies are needed to define the underlying mechanism of this association.
OBJECTIVE AND IMPORTANCE: Recent technological advances have provided clinicians with stents that can be navigated throughout the tortuous proximal vessels of the posterior intracranial circulation. There have been few reports of fusiform and wide-necked aneurysms treated with stents. Of the known risks involved in stent placement in the intracranial circulation, delayed stent thrombosis has not been well described. CLINICAL PRESENTATION: A 34-year-old man who experienced the sudden onset of a severe headache with increasing lethargy was found on computed tomographic imaging to have a subarachnoid hemorrhage. Angiography revealed a left vertebral artery fusiform aneurysm that incorporated the posteroinferior cerebellar artery origin. INTERVENTION: A low-porosity Magic Wallstent (Boston Scientific, Natick, MA) was placed in the left vertebral artery across the aneurysm and the origin of the posteroinferior cerebellar artery. Angiography performed 9 days later revealed significant reduction in filling of the aneurysm. The patient returned 3 months after stent placement with severe neurological deterioration from a brainstem infarction caused by complete thrombotic occlusion of the left vertebral artery at the stented segment of the vessel. CONCLUSION: Stenting of fusiform aneurysms has provided an alternative to surgical clipping or parent vessel reconstruction. With the increasing frequency of intracranial stent placement for various cerebrovascular disease entities, we must become aware of potential complications associated with these procedures. Such awareness may influence decision-making processes regarding treatment and follow-up care.
OBJECTIVE: We prospectively evaluated the safety and effectiveness of aggressive mechanical disruption of clot in conjunction with intra-arterial administration of a low-dose third-generation thrombolytic agent (reteplase) to treat ischemic stroke in patients who were considered poor candidates for intravenous alteplase therapy or who failed to improve after intravenous thrombolysis. Mechanical clot disruption was used if low-dose pharmacological thrombolysis was ineffective. This strategy was adopted to increase the recanalization rate without increasing the risk of intracerebral hemorrhage. METHODS: Patients were considered poor candidates for intravenous therapy because of severity of neurological deficits, interval from symptom onset to presentation of at least 3 hours, or recent major surgery. We administered a maximum total dose of 4 U of reteplase intra-arterially in 1-U increments via superselective catheterization. After the initial doses were administered, we performed mechanical angioplasty (for proximal occlusion) or snare manipulation (for distal occlusion) at the occlusion site if recanalization had not occurred. The remaining doses of thrombolytics were subsequently administered if required for further recanalization. Angiographic responses were graded using modified Thrombolysis in Myocardial Infarction (TIMI) criteria. Clinical evaluations were performed before and 24 hours, 7 to 10 days, and 1 to 3 months after treatment. RESULTS: Nineteen consecutive patients were treated (mean age, 64.3 +/- 16.2 yr; 10 were men). Initial National Institutes of Health Stroke Scale scores ranged from 11 to 42. Time from onset to treatment ranged from 1 to 9 hours. Occlusion sites were in the following arteries: cervical internal carotid (n = 7), intracranial internal carotid (n = 1), middle cerebral (n = 9), and basilar (n = 2). Of the 19 patients, thrombolysis alone was used in 5 patients, angioplasty was performed in 11 patients, and snare maneuvers were used in 5 patients. Complete restoration of blood flow (modified TIMI Grade 4) was observed in 12 patients, near-complete restoration of flow (modified TIMI Grade 3) in 4 patients, minimal response (modified TIMI Grade 1) in 1 patient, and no response in 2 patients (modified TIMI Grade 0). Neurological improvement at 24 hours (decline of at least 4 points in National Institutes of Health Stroke Scale score) was observed in seven patients. Five other patients experienced further improvement in National Institutes of Health Stroke Scale score at 7 to 10 days. No vessel rupture, dissection, or symptomatic intracranial hemorrhages were observed. At the time of follow-up evaluation, 7 of 19 patients were functionally independent. CONCLUSION: A high rate of recanalization and clinical improvement can be observed in patients with ischemic stroke using low-dose thrombolytic agents with adjunctive mechanical disruption of clot. Moreover, this strategy may reduce the risk of intracerebral hemorrhage observed with thrombolytics.
BACKGROUND: We report the occurrence of fatal intracerebral hemorrhage associated with using a combination of antithrombotic agents, including abciximab, in patients undergoing neurointerventional procedures. SUMMARY OF REPORT: Seven patients (average age 60, range 46 to 73 years) developed fatal intracerebral hemorrhages associated with neurointerventional procedures and the use of intravenous abciximab. The procedures included angioplasty and stent placement in the cervical internal carotid artery (n=4), angioplasty of the intracranial internal carotid artery (n=1), and angioplasty of the middle cerebral artery (n=2). Clinical deterioration was observed within 1 hour of the procedure in 5 patients and 7 and 8 hours after the procedure, respectively, in the remaining 2 patients. All patients had received heparin and clopidogrel; 6 had also received aspirin. CONCLUSIONS: Intracerebral hemorrhages can occur after neurointerventional procedures in patients with recent cerebral ischemic events, particularly when aggressive antithrombotic treatment is used.
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BACKGROUND AND PURPOSE: Although the short-term risks of stroke and types of stroke associated with isolated systolic hypertension (ISH) and borderline isolated systolic hypertension (BISH) have been described, the long-term effects of these hypertensive conditions, particularly in younger individuals, are unclear. We performed this study to evaluate the long-term risks of stroke, type of stroke, and predictors of stroke associated with ISH and BISH and how this risk compares with that for persons with diastolic hypertension and normotension. METHODS: We used the 20-year follow-up data for 12 344 adults aged 25 to 74 years who participated in the First National Health and Nutrition Examination Survey Follow-Up Study to determine the aforementioned risks. Blood pressure (BP) measurements of the participants were obtained during baseline evaluation. ISH was defined as systolic BP >/=160 mm Hg and diastolic BP <90 mm Hg. BISH was defined as systolic BP between 140 and 159 mm Hg and diastolic BP <90 mm Hg. Diastolic hypertension was defined as a diastolic BP >/=90 mm Hg. Normotension was defined as systolic BP <140 mm Hg and diastolic BP <90 mm Hg. Incidence of stroke overall and incidence of ischemic stroke and intracerebral hemorrhage were determined from a review of hospital records and death certificates. Relative risk (RR) of stroke and stroke type in association with each hypertensive category was determined by Cox proportional hazards analysis after adjustment for potential confounding variables. RESULTS: Among the 12 344 participants, hypertension was categorized as ISH (n=493), BISH (n=1241), and diastolic hypertension (n=3954). Normotension was observed in 6656 persons. After adjustment for differences in age, sex, education, serum cholesterol level, body mass index, diabetes mellitus, and cigarette smoking, a significantly higher RR for all strokes was observed in participants with ISH (RR, 2.7; 95% CI, 2.0 to 3.4) and BISH (RR, 1.4; 95% CI, 1.1 to 1.8) than those with normotension. The risk was significantly higher for ischemic stroke or intracerebral hemorrhage in persons with ISH and BISH. Among the 1734 persons with either ISH or BISH, the risk of stroke was independently associated with older age, diabetes mellitus, and systolic BP >/=180 mm Hg. CONCLUSIONS: Increased risks for stroke, ischemic stroke, and intracerebral hemorrhage were observed in patients with BISH, similar to those associated with ISH and diastolic hypertension. Future clinical trials are required to evaluate the effect of antihypertensive treatment in younger patients with BISH and ISH.
Endovascular treatment of aneurysms is an evolving technique. Endovascular techniques for the treatment of aneurysms have been available for 10 years. During this time, we have seen major advances and improvements in our ability to embolize aneurysms via an endoluminal approach. We have continued to modify our techniques and selection of patients who would most benefit from this approach. This article summarizes the current literature and attempts to develop a management strategy toward improving patient outcome by optimizing the choice between endovascular and surgical treatment modalities.
OBJECT: The authors report their experience with carotid artery stent placement (CASP) in patients with concomitant carotid artery (CA) and coronary artery (CorA) diseases. METHODS: In a review of 320 consecutive patients who underwent CASP, the authors identified 49 with severe CorA disease in addition to significant CA stenosis, who had undergone CASP before planned CorA bypass grafting (CorABG). The average age of these 49 patients was 68 years. In 39 patients (80%) the New York Heart Association functional classification grade was IV and in 10 the grade was III. In 26 patients 50% or greater stenosis of the left main CorA was found. Seventeen patients (35%) suffered from either significant hemodynamic contralateral CA stenosis (> 60% stenosis; eight patients) or contralateral CA occlusion (nine patients). Sixteen patients (33%) had symptomatic CA disease. No cerebrovascular events occurred during CorABG. Four patients (8%) died of cardiac arrest and one patient (2%) suffered a major stroke within 30 days after the CorABG procedure. No patient experienced clinically significant recurrent CA stenosis during the study period (average clinical follow-up period 27 months). CONCLUSIONS: Carotid artery stent placement should be considered as an alternative for the management of concomitant CA and CorA diseases. These preliminary results support the feasibility and durability of CASP in the population studied.
OBJECT: Carotid artery (CA) angioplasty with stent placement has been proposed as an alternative technique for revascularization in cases of CA stenosis. In this report the authors review the results of a multicenter Phase I study in which they evaluated the safety and feasibility of using a new self-expanding nitinol stent, the Bard Memotherm, to treat CA stenosis. METHODS: Enrollment was limited to patients in whom there was either 50% or greater symptomatic or 70% or greater asymptomatic stenosis of the internal CA. The primary endpoint was a technically successful implantation procedure (delivery of the stent to the target site and retrieval of the delivery device), resulting in less than 30% residual stenosis demonstrated on immediate postprocedure (control) angiograms, and no incidence of mortality, ipsilateral stroke, Q-wave myocardial infarction, or other major cardiovascular events immediately after or within 30 days following the procedure. Stent placement was attempted for 73 lesions in 71 patients (mean age 71.3 +/- 8.5 years), 43 (61%) of whom were men. The mean degree of stenosis was 82.6 +/- 9%. The stenosis was symptomatic in 27 (37%) and asymptomatic in 46 (63%) of 73 lesions. In four procedures the stent could not be delivered or released. The mean residual stenosis observed on angiograms was 3.8 +/- 6.9% in the 69 lesions treated with the Bard Memotherm stent; residual stenosis was greater than 30% in one of the 69 procedures. The primary endpoint was achieved in 65 (89%) of the 73 procedures. One patient experienced a major ischemic stroke and another patient died of intracerebral hemorrhage. The overall 1-month stroke rate was 2.7% for 73 attempted procedures. One patient died of pneumonia and acute respiratory distress syndrome, which occurred 3 weeks after the stent procedure and was unrelated to the procedure. CONCLUSIONS: The Memotherm stent can be used to treat patients with CA stenosis and is associated with a low peri-procedure complication rate. Long-term follow-up studies are underway to determine the impact of stent placement on the risk of ipsilateral ischemic events.
OBJECT: Medically refractory symptomatic vertebrobasilar atherosclerotic disease has a poor prognosis. Studies have shown that longer (> or = 10 mm), eccentric, high-grade (> 70%) stenoses portend increased procedure-related morbidity. The authors reviewed their experience to determine whether a staged procedure consisting of angioplasty followed by delayed (> or = 1 month later) repeated angioplasty and stent placement reduces the morbidity associated with endovascular treatment of symptomatic basilar and/or intracranial vertebral artery (VA) stenoses. METHODS: The authors retrospectively reviewed the medical records in a consecutive series of eight patients who underwent planned stent-assisted angioplasty for medically refractory, symptomatic atherosclerotic disease of the intracranial posterior circulation between February 1999 and January 2002. Staged stent-assisted angioplasty was planned for these patients because the extent and degree of stenosis of the VA and/or basilar artery (BA) lesion portended an excessive procedure-related risk. The degree of stenosis, recent onset of symptoms (unstable plaque), vessel tortuosity, and lesion length and morphological feaures were contributing factors in determining procedure-related risk. Patient records were analyzed for location and degree of stenosis, preprocedural regimen of antiplatelet and/or anticoagulation agents, devices used, procedure-related complications, and clinical and radiographic outcomes. Among the patients in whom staged stent-assisted angioplasty was planned, vessel dissection, which necessitated immediate stent placement, occurred during passage of the balloon in one of them. In a second patient, the stent could not be maneuvered through the tortuous VA. In a third patient, the VA and BAs remained widely patent after angioplasty alone, and therefore stent placement was not required. Significant complications among the eight patients included transient aphasia and hemiparesis in one and a groin hematoma that necessitated surgical intervention in another; there was no permanent neurological morbidity. The mean stenosis before treatment was 78%, which fell to 54% after angioplasty, and the mean residual stenosis after stent placement was 30%. At the last follow-up examination, none of the treated patients had further symptoms attributable to the treated stenosis. CONCLUSIONS: The novel combination of initial angioplasty followed by delayed endoluminal stent placement may reduce the neurological morbidity associated with endovascular treatment of long, high-grade stenotic lesions. Attempting to cross high-grade stenoses with higher-profile devices such as stents may result in an embolic shower. Furthermore, neointimal proliferation and scar formation after angioplasty result in a thickened fibrous layer, which may be protective during delayed stent deployment. Larger-scale studies involving multiple centers are needed to elucidate further the lesion morphological characteristics and patient population most likely to benefit from staged procedures.
BACKGROUND: The measurement of plasma apolipoproteins (APO) has been proposed for predicting the risk of cardiovascular diseases. However, the association between APOs and stroke is not well defined. MATERIAL/METHODS: We evaluated the association between plasma concentrations of APO A-1 and APO B with a physician diagnosis of stroke (n=153), and electrocardiogram evidence or physician diagnosis of myocardial infarction (n=379), in a nationally representative sample of 3,696 US adults aged >40 years who participated in the Third National Health and Nutrition Examination Survey. Multivariate logistic regression analyses were used to investigate these relationships. RESULTS: After adjusting for differences in age, gender, race/ethnicity, education, hypertension, cholesterol, body mass index, and cigarette smoking, the upper quartile of APO A-1 (> or = 161 mg/dl) when compared with the lowest quartile (<126 mg/dL) was inversely associated with the likelihood of myocardial infarction (Odds Ratio [OR], 0.6; 95% Confidence Interval [CI] 0.4-0.9) but not stroke. APO B concentrations were not associated with either myocardial infarction or stroke. However, an APO A-1 to B ratio > or = 1.59 when compared with a ratio < or = 1.04 was associated with a decreased likelihood of myocardial infarction (OR, 0.3; 95% CI, 0.2-0.6); and stroke (OR 0.4, 95% CI, 0.2-1.0). CONCLUSIONS: Higher APO A-1 concentrations were associated with a decreased likelihood for myocardial infarction but not for stroke. The APO A-1 to B ratio was inversely associated with both myocardial infarction and stroke and may be an important protective clinical marker for atherosclerosis.
INTRODUCTION: The transradial approach has been well described for arteriography of the coronary vessels. To assess the safety and success rate of the transradial approach for three-vessel or four-vessel diagnostic cerebral arteriography, we reviewed the experience at our institution and compared our complication rates with those found in the literature for transfemoral cerebral angiography and transradial coronary angiography. METHODS: We reviewed the electronic medical records of 129 consecutive patients in whom 132 cerebral angiographic studies were performed by use of a transradial approach between December 1999 and June 2001. A total of 54 selective catheterizations were performed, of which 39 were of the vertebral artery, 11 of the internal carotid artery, and 4 of the external carotid artery. Records were reviewed for periprocedural and delayed complications, indications for diagnostic angiography, and requirement of conversion to a femoral approach. Records were reviewed prospectively for the first 55 procedures and retrospectively for the next 77 procedures. RESULTS: The mean time to initial clinical follow-up was 1.5 months (median, 0.5 mo). The combined rate of periprocedural and delayed complications was 9%, and there were no major complications. Minor periprocedural complications included transient radial artery spasm (four patients), failure to access the brachial artery (two patients), severe pain (one patient), skin desquamation (one patient), and hematoma (one patient). There were no major complications. At the time of follow-up evaluation, these patients were without deficits related to cannulation of the radial artery. CONCLUSION: The transradial approach for cerebral angiography is a safe alternative to the transfemoral route. After transradial cerebral angiography, patients require a shorter observation period and are not restricted to bed rest. As technological developments generate smaller, more pliable endovascular surgical devices, future endovascular surgery may be performed transradially.
OBJECTIVE: Blood flow velocity (BFV) in the carotid artery is altered by stent placement. The significance of these alterations is unknown. In our experience, both standard BFV criteria for stenosis and customized criteria recommended by other authors have led to high rates of false-positive studies. We reviewed our experience with Doppler ultrasonography immediately after extracranial carotid artery stent placement to define criteria for restenosis by BFV. METHODS: Complete carotid angiograms and BFV results were available for 114 patients treated between January 1998 and December 1999. Angiographic images obtained immediately after stent placement and at follow-up were measured for residual or recurrent stenosis by a blinded reviewer according to the North American Symptomatic Carotid Endarterectomy Trial method. Results of BFV studies obtained within 1 week of stent placement were interpreted by using two standard criteria (A, peak in-stent systolic velocity greater than 125 cm/s; B, internal carotid artery-to-common carotid artery ratio greater than 3.0) and two customized criteria (C, peak in-stent velocity greater than 170 cm/s; D, internal carotid artery-to-common carotid artery ratio greater than 2.0). The results of follow-up angiography and the most recent Doppler study were compared for nine patients. RESULTS: On the basis of an examination of Doppler studies obtained immediately after stent placement, 36 patients met Criterion A for stenosis according to measured BFV (corresponding mean angiographic stenosis, 14.73 +/- 18.45%), 3 patients met Criterion B (mean stenosis, 1.67 +/- 2.89%), 8 patients met Criterion C (mean stenosis, 12.61 +/- 13.18%), and 14 met Criterion D (mean stenosis, 7.98 +/- 21.74%). No patient with Doppler criteria for significant stenosis had more than 50% residual stenosis. Three of nine patients who underwent follow-up angiography had stenosis of 50% or more; of these three patients, two underwent second angioplasty procedures. The peak in-stent systolic velocity or internal carotid artery-to-common carotid artery BFV ratio for each of the three patients with restenosis, but not for the six other patients, had increased by more than 80% since the immediate post-stenting Doppler study. CONCLUSION: Strict BFV criteria for restenosis after carotid artery stenting are less reliable than change in BFV over time. An immediate post-stenting Doppler study must be obtained to serve as a reference value for future follow-up evaluation.