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  • Electronic Resource  (3)
  • rupture  (2)
  • Computed tomography  (1)
  • 1
    Electronic Resource
    Electronic Resource
    Low frequency flow fluctuations in saccular aneurysms (1986)
    Springer
    Acta neurochirurgica 83 (1986), S. 131-137 
    Details
    ISSN: 0942-0940
    Keywords: Cerebral aneurysm ; aneurysm growth ; rupture ; turbulence
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Intra-operative Doppler recordings were carried out on cerebral saccular aneurysms in 12 patients. Distinct fluctuations of flow superimposed on the pulse wave were seen in 6 patients. The fluctuations appeared to be periodic with measured period lengths of 60 to 150 msec. In 3 other patients flow irregularities could be discerned acoustically but a definite periodicity could not be visualized on screen. In 3 patients flow appeared smooth during the entire pulse cycle, acoustically as well as visually. Concomitant flow observations in glass model aneurysms also revealed flow instabilities in certain aneurysm types at a Reynold's number of 300. All observed irregularities of flow were observed in zones of deceleration of flow in the models. Signs of fully developed turbulence were not found, neither in human aneurysms nor in the glass models. It appears likely that the fluctuations of flow induce vibrations of the aneurysmal wall and contibute to aneurysm progression and eventual rupture.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01402392
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Growth of aneurysms can be understood as passive yield to blood pressure (1989)
    Springer
    Acta neurochirurgica 100 (1989), S. 74-78 
    Details
    ISSN: 0942-0940
    Keywords: Cerebral aneurysm ; pathogenesis ; growth ; rupture ; yield stress ; stress relaxation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The strength of aneurysm walls obtained intraoperatively or at autopsy immediately after death was evaluated by measurements of the force response to one-directional stretch and compared to the walls of intracranial arteries. The maximum stress that aneurysm tissue could tolerate was found slightly lower than in arteries, which is most probably due to the amount of immature forms of collagen. The stress resistance of aneurysms and arterial tissue decayed over a period of several hours. The relaxation curve could be approximated by the sum of 2 exponential terms. The half decay times of these terms were found identical in aneurysms and arteries, they appear to be collagen characteristics. The strength measured in vitro was compared to the stress in vivo, which was calculated on the basis of blood pressure and aneurysm radius. The stress tolerated by aneurysm walls over a period of 24 hours was found to be in the range of the stress that is imposed in vivo by the mean blood pressure. Arteries resisted stresses corresponding to pressures 10 to 20 times higher than physiological values. The thickness of the aneurysm walls correlated with the aneurysm radius in a linear fashion. It is suggested that aneurysm growth can be understood as passive yield to blood pressure, and reactive healing and thickening of the wall with increasing aneurysm diameter.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01405279
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    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    Accuracy of high resolution computed tomography in direct diagnosis of cerebral aneurysms (1987)
    Springer
    Neuroradiology 29 (1987), S. 152-159 
    Details
    ISSN: 1432-1920
    Keywords: Cerebral aneurysms ; Computed tomography ; Cerebral angiography ; Subarachnoid hemorrhage
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary With high resolution computed tomography (CT) of the skull, performing rapid series of 1.5 mm slices during an intravenous bolus injection of contrast medium, an angiography-like image (angio-CT) of the basal cerebral arteries can be obtained. From 76 consecutive angiographically or autopsy-verified cerebral aneurysms of vaious size down to 3 mm in diameter, 74 (97.4%) were shown up by the angio-CT. One ruptured and one incidental aneurysm escaped CT visualization. Besides the correct localization of the aneurysms, angio-CT provides information concerning the size and main direction of the aneurysms and yields, in addition, a coronal view of the aneurysms and their surrounding structures. Pitfalls for mis-diagnosis can be the following: Aneurysms of below 5 mm in diameter, located at the supraclinoid part of the carotid artery, multiple or non-ruptured aneurysms, bony or movement artefacts, poorly contrasted vessels due to wrong injection technique of contrast medium or vasospasm, and incorrect interpretation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00327540
    Library Location Call Number Volume/Issue/Year Availability
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    Paper (German National Licenses)
    Fulltext
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