Showing papers by "L. Nelson Hopkins published in 2001"

Cocaine Use and the Likelihood of Nonfatal Myocardial Infarction and Stroke Data From the Third National Health and Nutrition Examination Survey

Abstract: Background—Numerous case series have implicated cocaine use as a cause of both myocardial infarction (MI) and stroke on the basis of the temporal relationship between drug use and event onset. Increasing cocaine use in the US population, especially in younger individuals, mandates a more extensive investigation of this relationship. Methods and Results—We determined the association of cocaine use with self-reported physician diagnosis of MI or stroke in a nationally representative sample of 10 085 US adults aged 18 to 45 years who participated in the Third National Health and Nutrition Examination Survey. A total of 46 nonfatal MIs and 33 nonfatal strokes were reported. After adjusting for differences in age, sex, race/ethnicity, education, hypertension, diabetes mellitus, cholesterol level, body mass index, and cigarette smoking, persons who reported frequent lifetime cocaine use had a significantly higher likelihood of nonfatal MI than nonusers (odds ratio, 6.9; 95% confidence interval, 1.3 to 58) but n...

Ineffective secondary prevention in survivors of cardiovascular events in the US population: report from the Third National Health and Nutrition Examination Survey.

Abstract: Background Survivors of myocardial infarction (MI) or stroke are at high risk for subsequent cardiovascular events. There is limited assessment of the effectiveness of risk factor modification through current secondary preventive strategies in the US population. We determined the adequacy of risk factor modification in 1252 survivors of MI, stroke, or both in a nationally representative sample of US adults and identified factors related to inadequate control of risk factors. Methods The adequacy of control for hypertension, diabetes mellitus, cigarette smoking, alcohol use, and hypercholesterolemia was assessed by personal interview, blood pressure measurements, and serum glycosylated hemoglobin and cholesterol levels in 17 752 US adults who participated in the Third National Health and Nutrition Examination Survey between 1988 and 1994. We also evaluated the role of potentially related factors, including age, sex, race/ethnicity, educational attainment, socioeconomic status, and medical insurance status using multivariate logistic regression analysis. Results Of 738 known hypertensive persons, hypertension was uncontrolled in 388 (53%). Previously undiagnosed hypertension was detected in 138 others (11%). Of 289 diabetic persons, serum glucose control was inadequate in 141. Of 1252 survivors, 225 (18%) were currently smoking, and heavy alcohol use was observed in 56 persons. Hypercholesterolemia was poorly controlled in 185 (46%) of 405 persons with known hypercholesterolemia. Undetected hypercholesterolemia was observed in 160 persons (13%). In the multivariate analysis, high-risk profiles were more likely to be observed in persons aged 46 to 65 years, women, and African Americans. Conclusions High prevalence of inadequate secondary prevention was found in a subset of the US population at highest risk for stroke and MI. Considerable efforts are required to effectively implement risk factor modification strategies after MI or stroke, particularly in middle-aged persons, African Americans, and women.

Angioplasty of intracranial occlusion resistant to thrombolysis in acute ischemic stroke.

Abstract: Objective Thrombolysis has been demonstrated to improve revascularization and outcome in patients with acute ischemic stroke. Many centers now apply thrombolytic therapy locally via intra-arterial infusion. One therapeutic benefit is the ability to cross soft clots with a guidewire and to perform mechanical thrombolysis. In some instances, reopened arteries reocclude as a result of either thrombosis or vasospasm. We report the use of balloon angioplasty during thrombolysis for acute stroke. Methods From June 1995 through June 1999, 49 patients underwent intra-arterial therapy for acute stroke. In this group, nine patients (seven men and two women) were treated with balloon angioplasty after inadequate recanalization with thrombolytic infusion. The mean age of these patients was 67.9 years. Nine matched control patients who underwent thrombolysis alone without angioplasty were chosen for comparison. Results In the group of nine patients who had angioplasty, the mean National Institutes of Health Stroke Scale score at presentation was 21.8 +/- 5.4. Four patients had residual distal occlusion after angioplasty, and one patient had a hemorrhagic conversion. Of the five patients in which recanalization was successful, none had reocclusion of the balloon-dilated vessel. The mean score at 30 days for the five survivors was 12.6 +/- 14.9, for an improvement of 7.0 +/- 14.2. Among the nine control patients, the mean score at presentation was 20.3 +/- 5.2; the mean score at 30 days for the five survivors was 19.4 +/- 7.7, for an improvement of 4.2 +/- 7.8. Conclusion In our experience, balloon angioplasty is a safe, effective adjuvant therapy in patients who are resistant to intra-arterial thrombolysis. The use of balloon angioplasty may prevent reocclusion in a stenotic artery and permit distal infusion of thrombolytic agents.

Intra-arterial third-generation recombinant tissue plasminogen activator (reteplase) for acute ischemic stroke.

Abstract: OBJECTIVE: We prospectively evaluated the safety and recanalization efficacy of intra-arterially administered reteplase, a third-generation recombinant tissue plasminogen activator, for treating ischemic stroke in patients considered poor candidates for intravenously administered alteplase therapy. METHODS: Patients were considered poor candidates for intravenously administered therapy because of severity of neurological deficits, interval from onset of symptoms to presentation of 3 hours or more, or recent major surgery. We administered a maximum total dose of 8 U of reteplase intra-arterially in 1-U increments via superselective catheterization. Adjunctive angioplasty of the occluded artery was performed in seven patients. Angiographic evidence of perfusion and thrombus was graded by use of modified Thrombolysis in Myocardial Infarction (TIMI) criteria. Neurological examinations were performed before and 24 hours and 7 to 10 days after treatment. RESULTS: Sixteen consecutive patients were treated (mean age, 64.1 ± 16.4 yr; seven were men). Initial National Institutes of Health Stroke Scale scores ranged from 10 to 26. Time from onset of symptoms to treatment ranged from 2 to 9 hours. Occlusion sites were the cervical internal carotid artery (n = 4), intracranial internal carotid artery (n = 4), middle cerebral artery (n = 6), and vertebrobasilar artery (n = 2). Complete or near-complete perfusion (TIMI Grade 3 or 4) was achieved in the arteries in 14 patients (88%), with partial recanalization (TIMI Grade 2) or minimal response (TIMI Grade 1) in the arteries in one patient each. Neurological improvement (defined as decrease of four or more points in National Institutes of Health Stroke Scale score) was observed in 7 (44%) of the 16 patients at 24 hours. Symptomatic intracerebral hemorrhage occurred in one patient; three other patients experienced intracerebral hemorrhages that did not result in neurological worsening. The overall mortality during hospitalization was 56%, related to massive ischemic stroke (n = 7), withdrawal of care at the family's request after the development of aspiration pneumonia and renal failure (n = 1), and a combination of intracerebral hemorrhage and massive ischemic stroke (n = 1). CONCLUSION: In this study, intra-arterially administered reteplase in doses up to 8 U with or without angioplasty resulted in a high rate of recanalization. This strategy should be considered in treating patients considered poor candidates for intravenous thrombolysis.

Risk factors for subarachnoid hemorrhage.

Abstract: Objective Cigarette smoking has been demonstrated to increase the risk of subarachnoid hemorrhage (SAH). Whether cessation of smoking decreases this risk remains unclear. We performed a case-control study to examine the effect of smoking and other known risk factors for cerebrovascular disease on the risk of SAH. Methods We reviewed the medical records of all patients with a diagnosis of SAH (n = 323) admitted to Johns Hopkins Hospital between January 1990 and June 1997. Controls matched for age, sex, and ethnicity (n = 969) were selected from a nationally representative sample of the Third National Health and Nutrition Examination Survey. We determined the independent association between smoking (current and previous) and various cerebrovascular risk factors and SAH by use of multivariate logistic regression analysis. A separate analysis was performed to determine associated risk factors for aneurysmal SAH. Results Of 323 patients admitted with SAH (mean age, 52.7+/-14 yr; 93 were men), 173 (54%) were hypertensive, 149 (46%) were currently smoking, and 125 (39%) were previous smokers. In the multivariate analysis, both previous smoking (odds ratio [OR], 4.5; 95% confidence interval [CI], 3.1-6.5) and current smoking (OR, 5.2; 95% CI, 3.6-7.5) were significantly associated with SAH. Hypertension was also significantly associated with SAH (OR, 2.4; 95% CI, 1.8-3.1). The risk factors for 290 patients with aneurysmal SAH were similar and included hypertension (OR, 2.4; 95% CI, 1.8-3.2), previous smoking (OR, 4.1; 95% CI, 2.7-6.0), and current smoking (OR, 5.4; 95% CI, 3.7-7.8). Conclusion Hypertension and cigarette smoking increase the risk for development of SAH, as found in previous studies. However, the increased risk persists even after cessation of cigarette smoking, which suggests the importance of early abstinence from smoking.

Quantitative analysis of injured, necrotic, and apoptotic cells in a new experimental model of intracerebral hemorrhage.

Abstract: OBJECTIVE To develop a new survival model of intracerebral hemorrhage (ICH) in rabbits and study the patterns of cellular injury in different regions 24 hrs after introduction of hematoma. Quantitation and characterization of injured cells in regions adjacent and distant to the hematoma have not been performed. DESIGN Prospective case-control study. SUBJECTS Ten New Zealand rabbits. INTERVENTION We introduced ICH in six anesthetized New Zealand rabbits by autologous blood injection under arterial pressure in the deep white matter in the frontal lobe. MEASUREMENTS AND MAIN RESULTS Hematoxylin and eosin staining was performed in six animals with ICH after 24 hrs to quantify intact, injured, and necrotic cells in regions proximal and distant to the hematoma, and the results were compared with four control animals. Terminal deoxynucleotidyl transferase dUTP nick-end labeling (TUNEL) staining was performed to quantify apoptotic cells in specified regions in five animals with ICH, and the results were compared with four control animals. All cell counts were performed by one investigator who used 100x oil emersion microscopy. The presence of localized hematoma was confirmed in all six animals with blood infusion. Compared with controls, animals with ICH had a significantly higher proportion of swollen cells in both the inner (55.9% +/- 3.0% vs. 26.8% +/- 1.7%; p < .05) and the outer (59.8% +/- 4.6% vs. 27.7% +/- 4.5%; p < .05) rim of the perihematoma region. A small proportion of shrunken dark cells were observed in both the inner (4.0% +/- 1.5%) and the outer (3.6% +/- 1.0%) rim of the perihematoma region. The remaining cells were considered morphologically intact. A large proportion of cells trapped within the matrix of the hematoma were either shrunken dark cells (48.8% +/- 16.4%) or swollen (38.8% +/- 15.1%). In the TUNEL-stained sections, a high burden of apoptotic cells was observed in the matrix of the hematoma (17.5 +/- 6.3 cells per high power field) but not in the perihematoma regions (less than two cells per high power field). CONCLUSIONS A reproducible model of ICH in rabbits is described. At 24 hrs, the perihematoma region contains relatively large proportions of morphologically intact or reversibly injured (swollen) cells, suggesting the possibility of an extended window for therapeutic intervention.

Endovascular treatment of intracranial aneurysms by using Guglielmi detachable coils in awake patients: safety and feasibility

Abstract: Object. Embolization of intracranial aneurysms performed using Guglielmi detachable coils (GDCs) is performed with the patient in a state of general anesthesia at most centers. Such an approach does not allow intraprocedural evaluation of the patient's neurological status and carries additional risks associated with general anesthesia and mechanical ventilation. At the authors' institution, GDC embolization of intracranial aneurysms is performed in awake patients after administration of sedative and analgesic agents (midazolam, fentanyl, morphine, and/or hydromorphone). To determine the feasibility and safety of this approach, the authors have retrospectively reviewed their clinical experience. Methods. The authors reviewed the medical records of all patients in whom GDC embolization for the treatment of intracranial aneurysms was undertaken between February 1, 1990 and October 31, 1999. Clinical presentation, medical comorbidities, anesthetic agents used, intraprocedural complications, and final procedur...

Role of Conventional Angiography in Evaluation of Patients With Carotid Artery Stenosis Demonstrated by Doppler Ultrasound in General Practice

Abstract: Background and Purpose— Previous studies have suggested that patients with carotid stenosis who are candidates for endarterectomy can be effectively identified on the basis of carotid Doppler ultrasound alone. Before widespread acceptance of this policy, the accuracy of carotid Doppler ultrasound outside selected centers and clinical trials needs to be evaluated. We performed a 12-month prospective study to evaluate the accuracy of Doppler ultrasound in identifying patients for carotid intervention in general practice settings. Methods— Each patient referred to our endovascular service for diagnostic angiography to evaluate for carotid stenosis was interviewed and examined by a neurologist. Subjects consisted of symptomatic patients with ≥50% stenosis and asymptomatic patients with ≥60% stenosis by Doppler ultrasound. Information pertaining to demographic and cerebrovascular risk factors and the results of the carotid Doppler ultrasound were recorded. The severity of stenosis on angiograms was measured wi...

Who should be screened for asymptomatic carotid artery stenosis? Experience from the Western New York Stroke Screening Program.

Abstract: OBJECTIVE Identification of significant asymptomatic carotid artery stenosis (ACAS) is important because of the stroke-risk reduction observed with carotid endarterectomy. The authors developed and validated a simple scoring system based on routinely available information to identify persons at high risk for ACAS using data collected during a community health screening program at various sites in western New York. A total of 1331 unselected volunteers without previous stroke, transient ischemic attack, or carotid artery surgery were evaluated by personal interview and duplex ultrasound. The main outcome measure was carotid artery stenosis > 60% by duplex ultrasound. In the derivation set (n = 887), 4 variables were significantly associated with ACAS > 60%: age > 65 years (odds ratio [OR] = 4.1, 95% confidence interval [CI] = 2.6-6.7), current smoking (OR = 2.0, 95% CI = 1.2-3.5), coronary artery disease (OR = 2.4, 95% CI = 1.5-3.9), and hypercholesterolemia (OR = 1.9, 95% CI = 1.2-2.9). Three risk groups (low, intermediate, and high) were defined on the basis of total risk score assigned on the basis of the strength of association. The scheme effectively stratified the validation set (n = 444); the likelihood ratio and posttest probability for ACAS in the high-risk group were 3.0 and 35%, respectively, and in the intermediate and low-risk groups were 1.4 and 20% and 0.4 and 7%, respectively. Routinely available information can be used to identify persons in the community at high risk for ACAS. Doppler ultrasound screening in this subgroup may prove to be cost-effective and have an effect on stroke-free survival.

Treating complex nervous system vascular disorders through a "needle stick": origins, evolution, and future of neuroendovascular therapy.

Abstract: In the past few decades, dramatic improvements have occurred in the field of neuroendovascular surgery. Endovascular therapy today is a well-established treatment modality for a variety of cerebrovascular and nonvascular central nervous system diseases. The foundation of this spectacular evolution was laid by the efforts of pioneering visionaries who often worked alone and under difficult, almost impossible, conditions. Ongoing device development and refinement have revolutionized the field at a dizzying, exhilarating pace. With a better understanding of the molecular basis of diseases and further advancements in gene therapy, neuroendovascular techniques have an enormous potential for application to the entire spectrum of central nervous system diseases as a minimally invasive vehicle for the delivery of biological factors.

Open-label Phase I Clinical Study to Assess the Safety of Intravenous Eptifibatide in Patients Undergoing Internal Carotid Artery Angioplasty and Stent Placement

Abstract: OBJECTIVE Eptifibatide, a competitive platelet glycoprotein IIb-IIIa receptor inhibitor with high selectivity and a short half-life, has been demonstrated to reduce the risk of ischemic events associated with coronary interventions However, its role in neurointerventional procedures needs to be analyzed We report the results of an open-label Phase I study to evaluate the safety of the use of eptifibatide during carotid angioplasty and stent placement METHODS Each study patient received eptifibatide administered intravenously as a 135-microg/kg single-dose bolus, then a 05-microg/kg/min infusion for 20 to 24 hours during carotid angioplasty and stent placement The primary efficacy end point was the 30-day composite occurrence of death, cerebral infarction, transient ischemic attack, and unplanned or urgent surgical intervention, thrombolysis, or subsequent percutaneous revascularization The primary safety end point was bleeding Bleeding complications were classified as major (hemoglobin decrease >5 g/dl), minor (hemoglobin decrease 3-5 g/dl), or insignificant RESULTS Ten patients (mean age, 73 yr; four men) were treated by use of the study protocol One patient developed a minor stroke postprocedurally (National Institutes of Health Stroke Scale score of 21 at 24 h that improved to 1 at 7 d) Three patients underwent scheduled coronary artery bypass graft surgery 4 to 12 days after undergoing carotid angioplasty and stent placement At 1-month follow-up, no new ischemic events were observed Major or minor bleeding was not observed in any patient Insignificant bleeding was observed in two patients CONCLUSION The use of eptifibatide as an adjunct to carotid angioplasty and stent placement seems to be safe Further studies are required to analyze the effectiveness and role of eptifibatide in neurointerventional procedures

Fatal progression of posttraumatic dural arteriovenous fistulas refractory to multimodal therapy: Case report

Abstract: The authors report the case of a man who suffered from progressive, disseminated posttraumatic dural arteriovenous fistulas (DAVFs) resulting in death, despite aggressive endovascular, surgical, and radiosurgical treatment. This 31-year-old man was struck on the head while playing basketball. Two weeks later a soft, pulsatile mass developed at his vertex, and the man began to experience pulsatile tinnitus and progressive headaches. Magnetic resonance imaging and subsequent angiography revealed multiple AVFs in the scalp, calvaria, and dura, with drainage into the superior sagittal sinus. The patient was treated initially with transarterial embolization in five stages, followed by vertex craniotomy and surgical resection of the AVFs. However, multiple additional DAVFs developed over the bilateral convexities, the falx, and the tentorium. Subsequent treatment entailed 15 stages of transarterial embolization; seven stages of transvenous embolization, including complete occlusion of the sagittal sinus and partial occlusion of the straight sinus; three stages of stereotactic radiosurgery; and a second craniotomy with aggressive disconnection of the DAVFs. Unfortunately, the fistulas continued to progress, resulting in diffuse venous hypertension, multiple intracerebral hemorrhages in both hemispheres, and, ultimately, death nearly 5 years after the initial trauma. Endovascular, surgical, and radiosurgical treatments are successful in curing most patients with DAVFs. The failure of multimodal therapy and the fulminant progression and disseminated nature of this patient's disease are unique.

Carotid endarterectomy: can we select surgical candidates at high risk for stroke and low risk for perioperative complications?

Abstract: DESPITE EVIDENCE OF the efficacy of carotid endarterectomy from the large randomized multicenter trials completed in the 1990s, the physician who treats patients with carotid artery stenosis still is faced with a difficult management decision. More recently, subgroup analyses have been conducted of asymptomatic and symptomatic patients enrolled in these trials to identify clinical and radiological factors that increase the rates of morbidity and mortality associated with surgery, as well as those that increase the risk of stroke without surgery. Knowledge of these factors is important to recommend the best course of action for the individual patient. In this article, we summarize the conclusions of some of the subgroup analyses from the major carotid endarterectomy trials.

Absence of early proinflammatory cytokine expression in experimental intracerebral hemorrhage.

Abstract: Objective We sought to analyze the regional concentrations of proinflammatory cytokines in the acute period of intracerebral hemorrhage (ICH) and to test the hypothesis that ICH is associated with the expression of proinflammatory cytokines in the acute period. Although the expression of cytokines and their role in neuronal injury and inflammation is well characterized in cerebral ischemia and head injury, no information exists regarding expression of cytokines in ICH. Methods We introduced ICH in eight anesthetized mongrel dogs by autologous blood injection (6 ml) under arterial pressure in the deep white matter adjacent to the left basal ganglia. Samples of arterial blood and cerebrospinal fluid were collected, and tissue extracts were prepared from different regions of the brain for immunoassay of tumor necrosis factor alpha, interleukin (IL)-1beta, and IL-6 concentrations in animals with and without ICH. Results The tumor necrosis factor a levels (+/- standard error) in the cerebrospinal fluid 1 hour after ICH did not differ significantly between the ICH group and the control group (7.1 +/- 1.3 pg/ml versus 10.8 +/- 2.3 pg/ml, P = 0.22). Levels in the perihematoma region in the ICH group (96.6 +/- 3.1 pg/ml) were not significantly different from those in the control group (93.4 +/- 6.7 pg/ml, P = 0.7). IL-6 levels (+/- standard error) in the perihematoma region in the ICH group (116.3 +/- 13.3 pg/ml) did not differ significantly from those in corresponding regions in the control group (122.3 +/- 12.8 pg/ml, P = 0.7). IL-1beta levels were below 5 pg/ml in serum, cerebrospinal fluid, and extracts of different brain regions. Conclusion The early pathophysiology of ICH does not involve significant expression of tumor necrosis factor a either in the perihematoma region or other regions of the brain. The observation suggests that the pathophysiology of ICH in the acute period is different from both cerebral ischemia and traumatic brain injury.

Program Requirements for Residency/Fellowship Education in Neuroendovascular Surgery/Interventional Neuroradiology: Special Report on Graduate Medical Education

Abstract: BACKGROUND AND PURPOSE Neuroendovascular surgery/interventional neuroradiology is a relatively new subspecialty that has been evolving since the mid-1970s. During the past 2 decades, significant advances have been made in this field of minimally invasive therapy for the treatment of intracranial cerebral aneurysms; acute stroke therapy intervention; cerebral arteriovenous malformations; carotid cavernous sinus fistulas; head, neck, and spinal cord vascular lesions; and other complex cerebrovascular diseases. Advanced postresidency fellowship programs have now been established in North America, Europe, and Japan, specifically for training in this new subspecialty. METHODS From 1986 to the present, an ad hoc committee of senior executive committee members from the American Society of Interventional and Therapeutic Neuroradiology, the Joint Section of Cerebrovascular Neurosurgery, and the American Society of Neuroradiology met to establish, by consensus, general guidelines for training physicians in this field. RESULTS In April 1999, the Executive Committee of the Joint Section of Cerebrovascular Neurosurgery voted unanimously to endorse these training standard guidelines. In May 1999, the Executive Committee of the American Society of Interventional and Therapeutic Neuroradiology and the American Society of Neuroradiology also unanimously voted to endorse these guidelines. In June 1999, the Executive Council of the American Association of Neurological Surgeons and the Congress of Neurological Surgeons unanimously voted to endorse these guidelines. CONCLUSION The following guidelines for residency/fellowship education have now been endorsed by the parent organization of both the interventional and diagnostic neuroradiology community, as well as both senior organizations representing neurosurgery in North America. These guidelines for training should be used as a reference and guide to any institution establishing a training program in neuroendovascular surgery/interventional neuroradiology.

Europium fluorescence to visualize N-butyl 2-cyanoacrylate in embolized vessels of an arteriovenous malformation swine model.

Abstract: BACKGROUND AND PURPOSE: Standard tissue staining using the lipid dye Oil-Red-O has been previously applied to stain vessel specimens, which were embolized with a mixture of n-butyl 2-cyanoacrylate (NBCA) and oil (Lipiodol). That technique, however, results in nonspecific and nonquantitative staining that does not provide the necessary differentiation between NBCA and Lipiodol. We present an innovative staining procedure that quantifies NBCA within treated tissues. METHODS: An arteriovenous malformation (AVM) model in swine was used to evaluate the polymerization characteristics of various ratios of Lipiodol/NBCA/glacial acetic acid (GAA) mixtures. To determine the depth of NBCA penetration within the AVM model and to characterize the polymerization patterns of various mixtures within the vessel, histologic cross- and longitudinal sections were prepared for microscopy. These paraffin-embedded tissue sections were stained with a europium aryl-β-diketone complex (TEC) to improve differentiation between NBCA and Lipiodol. Quantification of NBCA and Lipiodol within the lumen of rete cross-sections was accomplished using image analysis software to determine percent luminal area occluded by embolization. RESULTS: Upon application of TEC, intense europium fluorescence was seen when the tissue samples were excited by low-power UV light (excitation at 365 nm; emission at 614 nm). The area of europium intensity within the lumen corresponded to NBCA concentration, and addition of GAA aided the NBCA distribution throughout the lumen without affecting fluorescence intensity. It was seen that NBCA could be easily differentiated from Lipiodol and that quantification could be readily performed on these sections because of the improved differentiation. For the case of a 50:50 (vol. %) mixture with an added 20 μL of GAA, luminal area distribution of Lipiodol, NBCA, and blood products was 42.6 ± 3.5%, 33.8 ± 5.7%, and 23.7 ±2.7%, respectively. CONCLUSION: The rare earth metal europium, when added as a fluorescent chelate compound to histologic tissue sections, allowed for differentiation between NBCA and Lipiodol with good detail. These results have facilitated further characterization of NBCA polymerization for the use of AVM embolization.

Carbon dioxide column angioscopy: a new endovascular imaging technique.

Abstract: Summary: A new angioscopic technique with a CO2 gas medium for prolonged viewing sessions in the carotid artery is described. A stationary column of CO2 gas, angled 17–30° subhorizontally and buoyed against a balloon catheter, can be safely maintained. During 10–20-min sessions in dogs, endothelia, thrombi, stent filaments, coils, and an intimal flap were visualized. This technique eliminates the need for continuous saline infusion, which has prevented the application of angioscopy in the carotid artery.