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In medicine, Allen's test or the Allen test is a medical sign used in physical examination of arterial blood flow to the hands. It was named for Edgar Van Nuys Allen , who described the original version of the test in 1942.
However, the elements comprising Virchow's triad were not proposed by Virchow. Neither did he ever suggest a triad to describe the pathogenesis of venous thrombosis. In fact, it was not until decades after Virchow's death that a consensus was reached proposing that thrombosis is the result of alterations in blood flow, vascular endothelial ...
Arterial input function (AIF), also known as a plasma input function, refers to the concentration of tracer in blood-plasma in an artery measured over time. The oldest record on PubMed shows that AIF was used by Harvey et al. [1] in 1962 to measure the exchange of materials between red blood cells and blood plasma, and by other researchers in 1983 for positron emission tomography (PET) studies.
For this reason, the blood flow velocity is the fastest in the middle of the vessel and slowest at the vessel wall. In most cases, the mean velocity is used. [18] There are many ways to measure blood flow velocity, like videocapillary microscoping with frame-to-frame analysis, or laser Doppler anemometry. [19]
The Fick principle states that blood flow to an organ can be calculated using a marker substance if the following information is known: Amount of marker substance taken up by the organ per unit time; Concentration of marker substance in arterial blood supplying the organ; Concentration of marker substance in venous blood leaving the organ
The lumped parameter model consists in a system of ordinary differential equations that adhere to the principles of conservation of mass and momentum balance. The model is obtained exploiting the electrical analogy where the current represents the blood flow, the voltage represents the pressure difference, the electric resistance plays the role of the vascular resistance (determined by the ...
VEGF xxx may then cause the creation of new blood vessels in the retina and elsewhere in the eye, heralding changes that may threaten the sight. VEGF-A plays a role in the disease pathology of the wet form age-related macular degeneration (AMD), which is the leading cause of blindness for the elderly of the industrialized world. The vascular ...
When there is an injury to a blood vessel, the endothelial cells can release various vasoconstrictor substances, such as endothelin [23] and thromboxane, [24] to induce the constriction of the smooth muscles in the vessel wall. This helps reduce blood flow to the site of injury and limits bleeding.