PubMed Health⌕ Search

Biomedical subjects

L Nelson Hopkins

Publications and source records attributed to L Nelson Hopkins.

At least 55 records · Page 3Linked to original sources
PubMed2005

Frequency and management of recurrent stenosis after carotid artery stent implantation.

OBJECT: To determine the rate of hemodynamically significant recurrent carotid artery (CA) stenosis after stent-assisted angioplasty for CA occlusive disease, the authors analyzed Doppler ultrasonography data that had been prospectively collected between October 1998 and September 2002 for CA stent trials. METHODS: Patients included in the study participated in at least 6 months of follow-up review with serial Doppler studies or were found to have elevated in-stent velocities (> 300 cm/second) on postprocedure Doppler ultrasonograms. Hemodynamically significant (> or = 80%) recurrent stenosis was identified using the following Doppler criteria: peak in-stent systolic velocity at least 330 cm/second, peak in-stent diastolic velocity at least 130 cm/second, and peak internal carotid artery/common carotid artery velocity ratio at least 3.8. Follow-up studies were obtained at approximate fixed intervals of 1 day, 1 month, 6 months, and yearly. Angiography was performed in the event of recurrent symptoms, evidence of hemodynamically significant stenosis on Doppler ultrasonography, or both. Treatment was repeated because of symptoms, angiographic evidence of severe (> or = 80%) recurrent stenosis, or both of these. Stents were implanted in 142 vessels in 138 patients (all but five patients were considered high-risk surgical candidates and 25 patients were lost to follow-up review). For the remaining 112 patients (117 vessels), the mean duration of Doppler ultrasonography follow up was 16.42+/-10.58 months (range 4-54 months). Using one or more Doppler criteria, severe (> or = 80%) in-stent stenosis was detected in six patients (5%). Eight patients underwent repeated angiography. Six patients (three with symptoms) required repeated intervention (in four patients angioplasty alone; in one patient conventional angioplasty plus Cutting Balloon angioplasty; and in one patient stent-assisted angioplasty). CONCLUSIONS: In a subset of primarily high-risk surgical candidates treated with stent-assisted angioplasty, the rates of hemodynamically significant restenosis were comparable to surgical restenosis rates cited in previously published works. Treatment for recurrent stenosis incurred no instance of periprocedure neurological morbidity.

Angiography, Digital Subtraction↗
PubMed2005

A triple bifurcation aneurysm model for evaluating complex endovascular therapies in dogs.

OBJECT: Animal aneurysm models are required for the study of the hemodynamics and pathophysiology of intracranial aneurysms in humans and so that experimental treatments can be tested prior to clinical trials. The authors developed a canine model that consistently produces up to three bifurcation aneurysms similar in morphological features and hemodynamics to human intracranial aneurysms. METHODS: In 10 mongrel dogs, a harvested segment of the external jugular vein was anastamosed to an external carotid artery (CA)-lingual artery bifurcation arteriotomy site to create a lateral bifurcation aneurysm. The surgery was repeated on the contralateral side in each animal to form a second lateral bifurcation aneurysm and, in five dogs, a CA-CA crossover anastomosis was also performed to create a terminal bifurcation aneurysm. Nineteen of 20 lateral bifurcation aneurysms were confirmed in 10 dogs by diagnostic angiography 7 to 14 days after surgery. Aneurysm fundus-to-neck ratios ranged from 1 to 2, depending on the size of the arteriotomy. The terminal bifurcation aneurysms were confirmed in all five dogs by diagnostic angiography 7 to 14 days after the procedure. The authors later tested endovascular techniques for embolizing the aneurysms. CONCLUSIONS: Three bifurcation aneurysms of sufficient size for endovascular access can be created in a reproducible fashion in the same animal. This model is useful for studying complex endovascular procedures in aneurysms that mimic the human condition and for testing new devices and techniques.

Anastomosis, Surgical↗
PubMed2005

Perforation of external carotid artery branch arteries during endoluminal carotid revascularization procedures: consequences and management.

The purpose of this article is to describe several inadvertent perforations of external carotid artery branches that occurred in our laboratory during planned carotid artery stenting procedures. When known, the mechanism of the perforation is described. The treatment of these complications is discussed, along with a more general discussion of potential embolic materials. Perforation of branch arteries within the external carotid artery territory during planned carotid revascularization is an uncommon but potentially life-threatening complication. This complication can occur as a result of wire or catheter placement into these vessels. Early recognition of the perforation, prompt treatment of the bleeding, and control of the patient's airway are necessary to avoid a potentially catastrophic outcome.

Aged↗
PubMed2004

Natural history of unruptured intracranial aneurysms.

Since the publication of the retrospective part of the International Study of Unruptured Intracranial Aneurysms (ISUIA) in 1998, there has been a significant focus in the neurosurgical literature on the natural history of these lesions. The prospective data from the second part of the ISUIA, which was published in 2003, provided further evidence that small, asymptomatic intracranial aneurysms may have a more benign course than previously believed. With the data from the ISUIA as a reference point, in this paper the authors strive to provide a source of practical clinical data to aid cerebrovascular physicians in the initial decision to treat or observe a patient with a small, asymptomatic intracranial aneurysm. The issues covered will include previous rupture, symptoms other than rupture, aneurysm size, site, and aspect ratio. It is the authors' goal to provide a useful practical framework on the relevant clinical issues as an aid to practitioners treating patients who present with intracranial aneurysms.

Humans↗
PubMed2004

Intravenous abciximab for parent vessel thrombus during basilar apex aneurysm coil embolization: case report and literature review.

BACKGROUND: Parent vessel thrombus formation is a serious complication of intracranial aneurysm embolization. The management of this issue is controversial. Abciximab, a potent platelet inhibitor, has been shown to have thrombolytic effects during coronary interventions. A small number of cases have demonstrated its potential application in neuroendovascular procedures. We review the literature on the management of parent vessel thrombosis during aneurysm coil embolization and report our successful experience with the use of IV abciximab to treat parent vessel thrombus formation related to coil embolization of a basilar apex aneurysm. CASE DESCRIPTION: A 45-year-old man presented to our center with an incidental basilar apex aneurysm. After being informed of the surgical and endovascular treatment options, he elected to undergo coil embolization of the aneurysm. During the procedure, acute thrombus was noted in the left P1 segment of the posterior cerebral artery. IV abciximab was administered, and an angiogram the following day showed complete dissolution of the clot. The patient had no neurologic sequelae. CONCLUSIONS: IV abciximab appears to be an effective option in the management of acute parent vessel thrombus encountered during coil embolization of unruptured aneurysms. Sufficient data are lacking regarding its use in the setting of a ruptured aneurysm.

Abciximab↗
PubMed2004

Advances in stent-assisted management of intracranial occlusive disease and cerebral aneurysms.

The use of stents in the intracranial circulation has been made possible by rapid developments in stent technology in recent years. Considerable improvements in stent design, delivery devices, and technique have expanded the use of stenting to the treatment of intracranial disorders. This article reviews the indications for endovascular stenting for cerebral aneurysms and intracranial atherosclerosis and describes the peri-procedure management and technique applied at the Department of Neurosurgery at the University at Buffalo.

Angioplasty, Balloon↗
PubMed2004

Atherosclerotic occlusive extracranial vertebral artery disease: indications for intervention, endovascular techniques, short-term and long-term results.

BACKGROUND: Atherosclerotic occlusive disease of the vertebral artery (VA) affects a significant proportion of patients with cerebrovascular disease and can cause significant morbidity and mortality despite maximal medical therapy. Careful selection of both symptomatic and asymptomatic patients for intervention based on neurological symptoms, as well as anatomical and hemodynamic considerations, is essential. METHODS: To achieve proper results with angioplasty and stenting, standard endovascular techniques are modified for the unique anatomical considerations of the VA. Several technical nuances are described here to aid in the endoluminal revascularization of the VA. RESULTS: Technical success (<50% residual diameter stenosis) rates ranging from 94 to 98% and low rates of periprocedural complications have been achieved with VA angioplasty and stenting in select series with angiographic follow-up. The long-term success in those series is limited by the high (10-43%) rate of recurrent stenosis. Proper placement of the stent can reduce the risk of periprocedural complications and restenosis. In-stent stenosis appears most commonly during the first 6-12 months after stent placement, but does not appear to correlate with return of neurological symptoms. We believe the high rate of recurrent stenosis makes follow-up angiography essential, especially in the first 12 months after the procedure. CONCLUSION: Endovascular VA angioplasty with stent placement provides an innovative approach to treat a difficult clinical entity. Evolving therapies, including drug-eluting stents or bioresorbable stents, may prove to provide better long-term results.

Angioplasty, Balloon↗
PubMed2004

Patient selection for revascularization in cervical carotid artery disease: angioplasty and stenting vs. endarterectomy.

Cervical carotid stenosis is a major cause of stroke and disability. Although carotid endarterectomy is an established and effective treatment for some patients with carotid artery stenosis, angioplasty and stenting has emerged in recent years as a viable alternative, particularly for patients who may be less suited for surgery. This article reviews patient selection for the two alternative approaches. The authors review the findings of the major clinical trials of carotid endarterectomy, summarize the development of carotid angioplasty and stenting, and identify patient characteristics that may guide selection of surgical or endovascular treatment.

Angiography↗
PubMed2004

Measurement of flow modification in phantom aneurysm model: comparison of coils and a longitudinally and axially asymmetric stent--initial findings.

Dye-dilution imaging sequences were performed and time-density curves were constructed in elastomer vessel aneurysm models to demonstrate the effectiveness of coils and an asymmetric stent in disrupting standard vortex flow. Compared with the use of coils, the use of stents led to marked flow modification, as seen with imaging sequences, and substantially slower inflow, as indicated by time-density curves, owing to the low-porosity region of the stent that covers the aneurysm orifice. These flow examination results indicate that potentially favorable flow modification features can be created by using the described asymmetric stent design, the use of which may lead to alternative methods of image-guided endovascular cerebral aneurysm therapy.

Blood Vessel Prosthesis Implantation↗
PubMed2004

Update on endovascular treatment of cerebrovascular diseases.

Several developments in endovascular technology have greatly expanded the application of these techniques to treat extra- and intracranial cerebrovascular diseases. This review explores the indications, techniques, and clinical results for endovascular treatment of ischemic stroke and intracranial stenoses, aneurysms, and arteriovenous malformations.

Angioplasty, Balloon↗
PubMed2004

Bivalirudin for endovascular intervention in acute ischemic stroke: case report.

OBJECTIVE AND IMPORTANCE: Intra-arterial thrombolysis has been demonstrated to improve recanalization and outcomes among patients with acute ischemic stroke. However, thrombolytic agents have limited effectiveness and are associated with a significant risk of bleeding. Bivalirudin is a direct thrombin inhibitor that has been demonstrated in the cardiology literature to have a more favorable efficacy and bleeding profile than other antithrombotic medications. We report the use of bivalirudin during endovascular treatment of acute stroke, when hemorrhagic complications are not uncommon. CLINICAL PRESENTATION: A 71-year-old woman with atrial fibrillation presented with right hemiparesis and aphasia and was found to have a National Institutes of Health Stroke Scale score of 10. Computed tomographic scans revealed no evidence of intracranial hemorrhage, aneurysm, or ischemic stroke. Cerebral angiography revealed thromboembolic occlusion of the superior division of the left middle cerebral artery. INTERVENTION: For anticoagulation, a loading dose of bivalirudin was intravenously administered before the interventional procedure, followed by continuous infusion. Attempts to remove the clot with an endovascular snare failed to induce recanalization of the vessel. Bivalirudin was then administered intra-arterially. Immediate postprocedural angiography demonstrated restoration of flow in the left middle cerebral artery. Repeat computed tomographic scans demonstrated no intracranial hemorrhage. The patient's hemiparesis and aphasia were nearly resolved and her National Institutes of Health Stroke Scale score was 2 at the time of her discharge 5 days later. CONCLUSION: To our knowledge, this is the first report of the use of bivalirudin for treatment of acute ischemic stroke. Bivalirudin may be a useful agent for intravenous anticoagulation and intra-arterial thrombolysis in this setting.

Acute Disease↗
PubMed2004

Safety of high-dose intravenous eptifibatide as an adjunct to internal carotid artery angioplasty and stent placement: a prospective registry.

OBJECTIVE: Eptifibatide, a competitive platelet glycoprotein IIb-IIIa receptor inhibitor with high selectivity for platelet glycoprotein IIb-IIIa receptors and a short half-life, has been shown to reduce the risk of ischemic events associated with coronary interventions, particularly when used in high doses. However, its role in conjunction with neurointerventional procedures needs to be determined. We report the results of an open-label prospective registry to evaluate the safety (in terms of avoiding hemorrhagic complications) and effectiveness (in terms of preventing ischemic complications such as stroke) of administering high-dose eptifibatide during internal carotid artery angioplasty and stent placement (CAS) for extracranial carotid artery stenosis. METHODS: After femoral artery access was established and intravenous heparin (30 U/kg bolus) was administered, each patient was administered intravenous eptifibatide (two 180-microg/kg single-dose boluses before CAS, then a 2.0-microg/kg/min infusion for 20-24 hours thereafter). The primary end point was the 30-day composite occurrence of death, cerebral infarction, and unplanned or urgent endovascular or surgical intervention. The primary safety end point was bleeding, for which complications were classified according to the Thrombolysis in Myocardial Infarction scheme as major (hemoglobin decrease of more than 5 g/dl), minor (hemoglobin decrease of 3-5 g/dl), or insignificant. Platelet aggregation was measured in 13 consecutive patients with a rapid platelet-function analyzer. RESULTS: Twenty-six patients (mean age, 68.1 +/- 9.4 yr; 16 men) underwent treatment. The infusion and the CAS procedure were discontinued in one patient who developed angioneurotic edema after being administered intravenous heparin and the first bolus dose of eptifibatide. Among the 25 patients who underwent the procedure, no intracerebral hemorrhages and one minor ischemic stroke occurred during the 1-month follow-up period. The minor stroke was observed on postprocedure Day 7 in a patient for whom antiplatelet therapy was discontinued before a coronary artery bypass graft operation was performed. Another patient was discharged after an uncomplicated hospitalization but died as a result of urinary sepsis 12 days after CAS. One episode of major bleeding from the femoral insertion site required surgical repair and blood transfusions. Minor bleeding occurred in one patient. Platelet aggregation measurements obtained in 13 patients revealed a high degree (mean, 96%; range, 86-100%) of platelet inhibition after the administration of the second bolus dose of intravenous eptifibatide. CONCLUSION: High-dose eptifibatide administered as an adjunct to CAS seems to be safe. Further studies are required to analyze its effectiveness and role in neurointerventional procedures.

Adult↗
PubMed2004

Methods and design considerations for randomized clinical trials evaluating surgical or endovascular treatments for cerebrovascular diseases.

OBJECTIVE: The results of clinical trials affect the practice of surgery and endovascular therapy for cerebrovascular diseases. The purpose of this report is to review the basic components of the designs and methods for randomized clinical trials and to describe the influence of those components on the interpretation of trial results. METHODS: The goal of an optimal clinical trial of a new procedure is to provide the most objective and rigorous evaluation of the safety and effectiveness of that procedure. Anything in the design, performance, or analysis that impairs such an assessment decreases the ability of the trial to achieve its goal and answer the research question. To highlight the components of a clinical trial, this report uses examples of Phase III clinical trials that have influenced the practice of cerebrovascular surgery and endovascular therapy in the past three decades, including the International Cooperative Study of Extracranial/Intracranial Arterial Anastomosis, the North American Symptomatic Carotid Endarterectomy Trial, the Asymptomatic Carotid Atherosclerosis Study, the Prolyse in Acute Cerebral Thromboembolism II study, and the International Subarachnoid Aneurysm Trial. RESULTS: The research question (objective) of the trial must be clearly defined, with an objective measure of efficacy and a specified quantitative difference to define the superiority of one intervention over another, in a relatively homogeneous patient population. Allocation concealment, randomization with or without stratification, and blinding (or masking) are important strategies to prevent differences in the study populations that could adversely affect the conclusions of the study. The primary end point must correspond to the specific aims of the trial. It should be objectively defined, quantifiable, reliable, and reproducible. Commonly defined end points in surgical trials include changes from baseline illness or disease severity scores, morbidity and mortality rates, and relative risks of reaching an end point with time. The statistical methods used for interim and final analyses are important. The effects of dropouts, crossovers, and missing data should be understood in the context of the final analysis. Additional concepts, such as intention-to-treat analysis and use of actual versus predicted outcomes, are important with respect to interpretation of the final results of the study. CONCLUSION: The neurosurgical and neuroendovascular communities are currently planning or conducting several clinical trials to evaluate new procedures for the treatment of cerebrovascular diseases. It is hoped that a better understanding of the components of clinical trials will facilitate the design and implementation of effective studies.

Angioplasty↗
PubMed2004

Evolution of neuroendovascular intervention: a review of advancement in device technology.

Neuroendovascular surgery is a rapidly evolving field. Each year, numerous improvements are made in the endovascular surgeon's armamentarium. This evolution in technology, which is occurring at a dizzying pace, addresses many of the current limitations of neuroendovascular approaches. The potential to improve the outcomes of our patients is tremendous, particularly because one of the most common and most devastating neurological disorders, ischemic stroke, remains largely untreated. This article presents several of the new technologies that are currently being investigated or are under development and have the potential to lead to major advances in endovascular approaches for the treatment of intracranial and extracranial diseases.

Angioplasty↗
PubMed2004

Sirolimus-eluting stents in the canine cerebral vasculature: a prospective, randomized, blinded assessment of safety and vessel response.

OBJECT: Use of the sirolimus-eluting stent has led to a reduction of in-stent stenosis following treatment of coronary atherosclerosis, whereas treatment of intracranial atherosclerosis with bare-metal stents results in excessive restenosis rates of approximately 40%. Neurotoxicity effects and vessel injury are unknown in the cerebral vasculature. To assess the safety profile and vascular effects of sirolimus-coated stents, the authors conducted a prospective comparative study in which drug-eluting and bare-metal stents were implanted in the canine basilar artery (BA). METHODS: Sixteen mongrel dogs were randomized (eight animals per group) to receive either bare-metal 1.5 x 8-mm (six-cell) stents or sirolimus-eluting stents of the same dimensions. Interventionists, histopathologists, and histopathology technicians who participated in the study were blinded to the stent characteristics. Stents were implanted in the canine BA. Serial peripheral blood samples were obtained during the 1st week after implantation to determine the time-dependent serum concentration of sirolimus. Follow-up angiographic studies were performed 30 days after stent implantation to assess the effects of stent placement on the BA and brainstem perforating vessels. Explantation of the stent and BA was performed immediately after angiography by using a pressurized formalin fixation procedure. Histological and computer-assisted morphometric analyses of specimens obtained in each animal were performed. Sirolimus could not be detected in peripheral blood samples obtained later than 24 hours posttreatment. On follow-up angiography, all perforating vessels observed on initial angiograms remained patent, and no evidence of parent vessel damage or pseudoaneurysm formation was observed. Explanted vessels and brainstem sections did not demonstrate evidence of histological neurotoxicity, such as gliosis or infarction. No significant differences were found in the time to endothelialization of bare-metal and sirolimus-coated stents. Smooth-muscle cell (SMC) proliferation, the putative agent for restenosis, was lower in animals receiving sirolimus-coated stents (p = 0.003). Additionally, intimal fibrin density was increased in the dogs treated with sirolimus-coated stents (p < 0.0001). Histological evidence of an inflammatory response demonstrated a trend toward a reduced response in the sirolimus group (mean 0.58) compared with the bare-metal group (mean 0.83, p = 0.33). CONCLUSIONS: No neurotoxic effects were observed in the intracranial vessel walls or brainstem tissue in which sirolimus-coated stents were implanted. Compared with bare-metal stents, the sirolimus-coated devices did not impair endothelialization and, furthermore, tended to reduce the proliferation of SMCs. These findings indicate that sirolimus-coated devices may inhibit in-stent stenosis. Further studies with longer-term follow up are required to assess the restenosis rates of sirolimus-coated stents implanted in the intracranial vasculature.

Animals↗