Clinical Cerebrovascular Anatomy
Division of Cardiovascular Medicine, Cleveland Clinic, Cleveland, Ohio 44195, USA.Catheterization and Cardiovascular Interventions (Impact Factor: 2.11). 01/2009; 75(4):530-9. DOI: 10.1002/ccd.22299
Stroke is often the result of carotid atheroma, which may cause ischemia via progressive arterial narrowing or lead to superimposed thrombus formation and subsequent atheroembolism to the intracerebral vasculature. Revascularization through carotid endarterectomy or carotid artery stenting with embolic protection devices has produced favorable results in appropriately selected patients. In planning the percutaneous approach, an arch aortogram is first acquired to determine arch type and identify the presence of any anatomic variants which may affect the approach to the procedure and catheter selection. Subsequent imaging of the cerebral vasculature is performed to delineate the collateral circulation that is present, including an evaluation of the Circle of Willis. Although Doppler ultrasound, computed tomography (CT), and magnetic resonance angiography (MRA) may be useful in evaluating the presence of carotid or cerebrovascular disease, digital subtraction angiography is required prior to performance of a percutaneous intervention in order to create a procedural "roadmap". Additionally, the comprehensive management of cerebrovascular disease requires a detailed knowledge of the specific clinical syndromes that result from ischemia in each vascular territory. This methodical review of cerebrovascular anatomy and stroke syndromes will provide the operator with the tools to conduct a thorough neurological assessment prior to revascularization, evaluate any periprocedural complications that may arise, and evaluate the patient with suspected stroke.
Conference Paper: Fieldbus network implementation based on RS-485[Show abstract] [Hide abstract]
ABSTRACT: First, in this paper we present the integral structure of RS-485 fieldbus network in practical industrial applications. Through designing and implementing RS-485 fieldbus control systems, we gained much experience in configuration of resistor termination network, noise elimination on floating transmission lines, transmission control, multi communication station addressing and flow control. Then we discuss those points in detail. Finally, we consider the problems of network reliability and multi station real time data acquisition and control.
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ABSTRACT: Several multicentre, randomized trials have validated the efficacy of carotid endarterectomy (CEA). Comparative randomized trials are also currently developing insight into the role of carotid angioplasty and stenting (CAS), and identifying factors for optimal patient selection. Although these interventions are aimed at embolic stroke prevention, anaesthetic management might prevent the subset of strokes that are haemodynamic in nature by maintaining tight physiological control. The perioperative risk of myocardial events is increased in this population. Hence, preoperative attention to cardiovascular disease, hypertension, renal insufficiency, and diabetes mellitus might reduce neurological and cardiovascular complications. During carotid artery cross-clamping, the risk of cerebral ischaemia can be decreased by maintaining normal to high perfusion pressure. Although there is no demonstrable advantage of a specific anaesthetic technique for patients undergoing CEA, it is imperative that cerebral blood flow is optimized, that there is minimal cardiac stress, and that anaesthetic recovery is rapid. Carotid angioplasty and stenting is performed under light sedation with antithrombotic therapy and vigilance for bradycardia and hypotension. Tight haemodynamic control remains a priority in the immediate postoperative period for both interventions.
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ABSTRACT: Ischaemic stroke results from acute arterial occlusion leading to focal hypoperfusion. Thrombolysis is the only proven treatment. Advanced neuroimaging techniques allow a detailed assessment of the cerebral circulation in patients with acute stroke, and provide information about the status of collateral vessels and collateral blood flow, which could attenuate the effects of arterial occlusion. Imaging of the brain and vessels has shown that collateral flow can sustain brain tissue for hours after the occlusion of major arteries to the brain, and the augmentation or maintenance of collateral flow is therefore a potential therapeutic target. Several interventions that might augment collateral blood flow are being investigated.
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