Venous blood flow velocities in the parasellar region: a TCD and TCCS study O. Hoffmann, F. Doepp, J.M. Valdueza. Department of Neurology. University Hospital Charit�, Humboldt University Berlin, Germany

External pneumatic compression of the lower legs is effective as prophylaxis against deep vein thrombosis. In a typical application, inflatable cuffs are wrapped around the patient’s legs and periodically inflated to prevent stasis, accelerate venous blood flow, and enhance fibrinolysis. The purpose of this study was to examine the stress distribution within the tissues, and the corresponding venous blood flow and intravascular shear stress with different external compression modalities. A two-dimensional finite element analysis (FEA) was used to determine venous collapse as a function of internal (venous) pressure and the magnitude and spatial distribution of external (surface) pressure. Using the one-dimensional equations governing flow in a collapsible tube and the relations for venous collapse from the FEA, blood flow resulting from external compression was simulated. Tests were conducted to compare circumferentially symmetric (C) and asymmetric (A) compression and to examine distributions of pressure along the limb. Results show that A compression produces greater vessel collapse and generates larger blood flow velocities and shear stresses than C compression. The differences between axially uniform and graded-sequential compression are less marked than previously found, with uniform compression providing slightly greater peak flow velocities and shear stresses. The major advantage of graded-sequential compression is found at midcalf. Strains at the lumenal border are approximately 20 percent at an external pressure of 50 mmHg (6650 Pa) with all compression modalities.

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Assessment of blood flow velocities and venous pressures using a dual-sensor guidewire in symptomatic dural sinus stenoses

Journal of Neurosurgery ◽

10.3171/2017.12.jns172364 ◽

2019 ◽

Vol 130 (6) ◽

pp. 1992-1996 ◽

Cited By ~ 2

Author(s):

Stéphanie Lenck ◽

Fabrice Vallée ◽

Vittorio Civelli ◽

Jean-Pierre Saint-Maurice ◽

Patrick Nicholson ◽

...

Keyword(s):

Blood Flow ◽

Intracranial Hypertension ◽

Idiopathic Intracranial Hypertension ◽

Venous Pressure ◽

Venous Blood Flow ◽

Lateral Sinus ◽

Pulsatile Tinnitus ◽

Dual Sensor ◽

Blood Flow Velocities ◽

Flow Velocities

Lateral venous sinus stenoses have been associated with idiopathic intracranial hypertension and venous pulsatile tinnitus. Venous pressure measurement is traditionally performed to assess the indications for stenting in patients with idiopathic intracranial hypertension. However, its reliability has recently been questioned by many authors. The dual-sensor guidewire was first developed for advanced physiological assessment of fractional and coronary flow reserves in coronary artery stenoses. It allows measurement of both venous pressure and blood flow velocities. The authors used this device in 14 consecutively treated patients to explore for symptomatic lateral sinus stenosis. They found that venous blood flow was significantly accelerated inside the stenotic lesion. This acceleration, as well as the pulsatile tinnitus, resolved in all patients following stent placement. According to the authors’ results, this guidewire can be helpful for establishing an indication for stenting in patients with pulsatile tinnitus and idiopathic intracranial hypertension.

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Patterns of Cerebral Blood Flow and Systemic Hemodynamics During Arithmetic Processing

Journal of Psychophysiology ◽

10.1027/0269-8803.22.2.81 ◽

2008 ◽

Vol 22 (2) ◽

pp. 81-90 ◽

Cited By ~ 21

Author(s):

Natalie Werner ◽

Neval Kapan ◽

Gustavo A. Reyes del Paso

Keyword(s):

Blood Pressure ◽

Blood Flow ◽

Cerebral Blood Flow ◽

Time Course ◽

Doppler Sonography ◽

Transcranial Doppler Sonography ◽

Systemic Hemodynamics ◽

Heart Period ◽

Blood Flow Velocities ◽

Flow Velocities

The present study explored modulations in cerebral blood flow and systemic hemodynamics during the execution of a mental calculation task in 41 healthy subjects. Time course and lateralization of blood flow velocities in the medial cerebral arteries of both hemispheres were assessed using functional transcranial Doppler sonography. Indices of systemic hemodynamics were obtained using continuous blood pressure recordings. Doppler sonography revealed a biphasic left dominant rise in cerebral blood flow velocities during task execution. Systemic blood pressure increased, whereas heart period, heart period variability, and baroreflex sensitivity declined. Blood pressure and heart period proved predictive of the magnitude of the cerebral blood flow response, particularly of its initial component. Various physiological mechanisms may be assumed to be involved in cardiovascular adjustment to cognitive demands. While specific contributions of the sympathetic and parasympathetic systems may account for the observed pattern of systemic hemodynamics, flow metabolism coupling, fast neurogenic vasodilation, and cerebral autoregulation may be involved in mediating cerebral blood flow modulations. Furthermore, during conditions of high cardiovascular reactivity, systemic hemodynamic changes exert a marked influence on cerebral blood perfusion.

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Norethynodrel with mestranol and venous blood flow

JAMA ◽

10.1001/jama.198.7.784 ◽

1966 ◽

Vol 198 (7) ◽

pp. 784-785 ◽

Cited By ~ 1

Author(s):

A. Neistadt

Keyword(s):

Blood Flow ◽

Venous Blood ◽

Venous Blood Flow

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