shunt

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Related to arteriovenous shunt: Arteriovenous malformation

shunt

1. a railway point
2. Electronics a low-resistance conductor connected in parallel across a device, circuit, or part of a circuit to provide an alternative path for a known fraction of the current
3. Med a channel that bypasses the normal circulation of the blood: a congenital abnormality or surgically induced
4. Brit informal a collision which occurs when a vehicle runs into the back of the vehicle in front
Collins Discovery Encyclopedia, 1st edition © HarperCollins Publishers 2005
The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.

Shunt

 

an electrical or magnetic conductor connected in parallel with an electric or magnetic circuit to divert part of the electric current or magnetic flux when it is undesirable or impossible to pass all the current or flux through the circuit. For example, when a shunt is used to extend the measuring range of an ammeter, the current Ix being measured is divided between the shunt and the ammeter in inverse proportion to their respective resistances, Rs and RA; in this case Ix = IA (1 + RA/RS) = IAks, where IA is the value of the current as determined from the ammeter readings and ks is the shunting factor. For convenience in making current measurements, the resistance of the shunt is chosen so that ks is equal to 10,100, or 1000.

Shunts are manufactured in the form of plates, bands, and wires, primarily of manganin or constantan (for electrical shunts) or of a soft magnetic material (for magnetic shunts).

The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.

shunt

[shənt]
(civil engineering)
To shove or turn off to one side, as a car or train from one track to another.
(electricity)
A precision low-value resistor placed across the terminals of an ammeter to increase its range by allowing a known fraction of the circuit current to go around the meter. Also known as electric shunt.
To place one part in parallel with another.
(electromagnetism)
A piece of iron that provides a parallel path for magnetic flux around an air gap in a magnetic circuit.
(medicine)
A vascular passage by which blood is diverted from its normal circulatory path; frequently it is a surgical passage created between two blood vessels, but it may also be an anatomical feature.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.

shunt

To divert, switch or bypass.
Copyright © 1981-2019 by The Computer Language Company Inc. All Rights reserved. THIS DEFINITION IS FOR PERSONAL USE ONLY. All other reproduction is strictly prohibited without permission from the publisher.
References in periodicals archive ?
Table 3 Cutaneous manifestations due to arteriovenous shunt (n=350).
have reported the incidence of fungal infection in patients undergoing hemodialysis to be 67%.7 Cutaneous complications originating due to arteriovenous shunt include infection, phlebitis and hematoma.8,12,13 However, arteriovenous shunt dermatitis (both irritant and allergic) may also develop.7,12 Vascular complications of arteriovenous fistula construction include digital ischemia and aneurysm formation.6,7,8 Gynecomastia is the finding noted especially in cases who are on hemodialysis and may be reversed by a low phosphorus diet and
Chorioangioma can provide arteriovenous shunt that can lead to fetal cardiomegaly and fetal heart failure.
Hemangioma or cavernoma often cause confusion in diagnosis especially in early stages, which unlike AVM are well-demarcated and do not have arteriovenous shunts.11 AVMs show flow void signs on MRI due to the rapid flow in the lesions.8 The diagnosis of AVM in the present case was made by contrast enhanced CT and MRI brain and the feeding vessels viz., superficial temporal artery, internal maxillary and middle meningeal arteries were demonstrated by MRI neck angiography.
Interestingly, many authors presumed the presence of spontaneous portovenous shunt, such as gastrosplenorenal shunt or anomalous arteriovenous shunts, as a culprit for distant embolization.
During hospitalization, the patient presented several episodes of epistaxis, and deterioration of cardiopulmonary function with higher oxygen requirements secondary to pulmonary arteriovenous shunts. Gastrointestinal, liver or central nervous system shunts were discarded.
Arteriovenous shunts created for hemodialysis have been identified as cause of unexplained PH in patients with end-stage renal disease.
Raynaud's phenomenon is an abnormal vasospasm of digital arteries, precapillary arterioles, and dermal arteriovenous shunts that occurs in response to cold and various other stimuli.
Four types have been defined: the Stewart-Blue-farb type accompanying chronic arteriovenous malformations, the Mali type accompanying stasis dermatitis, a type accompanying the first gestation, and a type accompanying arteriovenous shunts in patients with chronic kidney failure (3).
Bilateral subcortical and basal ganglia calcification has been rarely reported in literature to be associated with dural areteriovenous fistula (AVF).3,4 Dural AVFs are abnormal arteriovenous connections that are located within the dura mater and involve a dural sinus and/or cortical veins and constitute 10-15% of all intracranial arteriovenous shunts. The dural AVF have been found to be associated with chronic venous reflux which has been postulated to result in subcortical calcifications.5 A case of characteristic calcification in the cortico-medullary junction at the bottom of cerebral sulci and basal ganglia in a patient with both AVM and dural AVF is reported.