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Werner Hassler, Armin Thron and Ernst H. Grote

high venous pressure is presumed to be the cause of clinical symptoms. 9, 20, 33, 35 Until now, pressure and flow velocity in spinal dural AV fistulas have not been measured. The present study was undertaken to elucidate the hemodynamic conditions of these malformations. Doppler sonography was used to measure blood flow velocities in feeding and draining vessels before and after surgery. Clinical Material and Methods Intraoperative studies were performed in nine of 25 patients operated on in the last 5 years for spinal dural AV fistulas. Doppler and pressure

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Marco Lee, Greg Zaharchuk, Raphael Guzman, Achal Achrol, Teresa Bell-Stephens and Gary K. Steinberg

– 57 , 1995 21 Nariai T , Matsushima Y , Imae S , Tanaka Y , Ishii K , Senda M , : Severe haemodynamic stress in selected subtypes of patients with moyamoya disease: a positron emission tomography study . J Neurol Neurosurg Psychiatry 76 : 663 – 669 , 2005 22 Nariai T , Senda M , Ishii K , Wakabayashi S , Yokota T , Toyama H , : Posthyperventilatory steal response in chronic cerebral hemodynamic stress: a positron emission tomography study . Stroke 29 : 1281 – 1292 , 1998 23 Ogawa A , Yoshimoto T , Suzuki J

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Miguel Bussière, Stephen P. Lownie, Donald Lee, Irene Gulka, Andrew Leung and David M. Pelz

T he baroreceptor reflex, a feedback loop between baroreceptors located in the wall of the carotid sinus, brainstem nuclei, and autonomic fibers projecting to the heart and peripheral vasculature, carefully regulates systemic blood pressure. 24 Heart rate, cardiac output, and peripheral vascular resistance are altered to regulate blood pressure. The development of atherosclerotic plaques in the region of the carotid sinus and subsequent carotid revascularization procedures can alter or impair the function of this reflex. 4 , 20 , 23 , 26 Hemodynamic

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Sauson Soldozy, Pedro Norat, Mazin Elsarrag, Ajay Chatrath, John S. Costello, Jennifer D. Sokolowski, Petr Tvrdik, M. Yashar S. Kalani and Min S. Park

often considered. 17 , 63 Recently, considerable research has focused on the relationship between hemodynamic stressors and aneurysm pathogenesis. From a mathematical and biophysical standpoint, aneurysm morphology and evolution over time is highly complex due to the heterogeneous nature of fluid mechanics. Complicating matters even further is the living nature of blood vessels, i.e., mechanical stimuli are transduced into biological signals, triggering inflammatory cascades and, ultimately, a wide range of transcriptional and signaling changes that lead to vascular

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Prem Venugopal, Daniel Valentino, Holger Schmitt, J. Pablo Villablanca, Fernando Viñuela and Gary Duckwiler

D iseases of the cerebrovasculature, such as stroke, are a leading cause of death and disability in developed countries. Cerebral aneurysms are dilations of the vascular wall, the rupture of which can lead to the most severe form of stroke—hemorrhagic stroke. The anatomy, hemodynamics, and biomechanics of the vasculature are believed to be important in the growth and rupture of these vascular lesions, but little is known about the relative significance of these factors. Numerical simulations can facilitate the investigation of brain aneurysm hemodynamics

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Shouri Lahiri, Mani Nezhad, Konrad H. Schlick, Brenda Rinsky, Axel Rosengart, Stephan A. Mayer and Patrick D. Lyden

N icardipine is commonly used for blood pressure reduction in patients with acute stroke. It is a dihydropyridine calcium channel antagonist that acts on vascular smooth muscle and reduces systemic vascular resistance and blood pressure. 3 , 9 In addition, nicardipine is a potent vasodilator of the systemic venous circulation, which contains approximately 70% of total blood volume. 3 , 5 , 9 Few studies have described the effect of nicardipine on cerebrovascular hemodynamics when the drug is administered intravenously. Under standard conditions, measured

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Muhammad Owais Khan, Veronica Toro Arana, Christian Rubbert, Jan F. Cornelius, Igor Fischer, Richard Bostelmann, Hendrik-Jan Mijderwijk, Bernd Turowski, Hans-Jakob Steiger, Rebecca May and Athanasios K. Petridis

Hemodynamic forces are thought to play a key role in IA wall deterioration but are difficult to reliably assess through current imaging modalities. Over the past decade, computational fluid dynamics (CFD) has emerged as a promising tool to noninvasively evaluate the hemodynamic forces to which the IA wall is exposed, leading to IA wall deterioration, particularly wall shear stress (WSS), and thus CFD can be used to investigate the underlying biomechanical phenomena involved in aneurysm pathophysiology. 6 , 39 Although CFD studies have retrospectively characterized hundreds

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Toru Iwama, Kohei Hayashida, Jun C. Takahashi, Izumi Nagata and Nobuo Hashimoto

L ow-resistance shunts in cerebral AVMs influence the hemodynamic and/or metabolic condition of brains affected by AVMs. As a result of these arteriovenous shunts, pressure is decreased in the feeding arteries and increased in the draining veins. The diversion of blood from surrounding brain tissue to the AVM—the intracranial steal phenomenon—may result in cerebral ischemia. 5, 7 In addition, increased pressure in draining veins may lead to congestive conditions in normal brain tissue from which blood courses into the draining system of the AVM. The

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Alexander M. Nixon, Murat Gunel and Bauer E. Sumpio

atherosclerosis, the latter including both extracranial (such as CA disease) and intracranial atherosclerosis. Hemodynamic Forces In general, blood flow in the vasculature can conform to 1 of 2 patterns: laminar or turbulent. 64 During turbulent flow there is rapid and often random temporal and spatial variation of velocity at any given point. This type of flow is not usually observed under normal conditions in the human vasculature, and it may contribute to vascular disease. 99 , 142 Conversely, laminar flow is present in large straight arterial segments under

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Ho Jun Seol, Duk Chul Shin, Yoo Seok Kim, Eun Bo Shim, Seung-Ki Kim, Byung-Kyu Cho and Kyu-Chang Wang

etiology and the reason it involves the major intracranial vessels, such as the distal ICA, adjacent proximal MCA, and proximal ACA at the initial disease stage, remain unclear. No report in the literature has revealed the relationship between this phenomenon and hemodynamic factors. Only a local regional hemodynamic measurement has been possible through usual experimental approaches for vascular disease. Measuring small vessels such as the cerebral arteries is very difficult from a technical point of view. Recently, it has become possible to delineate most properties in