Stroke; a journal of cerebral circulation
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Randomized Controlled Trial Clinical Trial
Trial of secondary prevention with atenolol after transient ischemic attack or nondisabling ischemic stroke. The Dutch TIA Trial Study Group.
beta-Blockers prevent vascular events in patients after myocardial infarction and lower blood pressure, the main risk factor for stroke. Hence, we assessed the effects of atenolol on the occurrence of death from vascular causes, stroke, or myocardial infarction and on blood pressure in patients after a transient ischemic attack or nondisabling ischemic stroke. ⋯ Our data neither confirm nor rule out that atenolol prevents important vascular events in patients after transient ischemic attack or nondisabling ischemic stroke, given the modest effect on blood pressure, the restrictions in patient selection, and the limited number of patient-years.
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Outcome from sinus vein thrombosis is very variable, with symptoms from headache to coma. Experimental findings suggest that an involvement of cortical veins is necessary to affect the cerebral microcirculation. Laser Doppler flowmetry was used to investigate the regional and temporal changes in local cortical blood flow after experimental occlusion and thrombosis of the superior sagittal sinus and tributary cortical veins in rats. ⋯ The data support the contention that sinus vein thrombosis evolves gradually, with major symptoms occurring only if the thrombus expands from the sinus into bridging and cortical veins. Collateral venous outflow pathways are thereby occluded, and local blood flow may become reduced to and below the ischemic threshold.
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Little is known about the effects of hypothermia on cerebral autoregulation. The present study was designed to examine cerebral blood flow responses to controlled hemorrhagic hypotension in normothermic and hypothermic rats. ⋯ Different PaCO2 management schemes used during hypothermia may have profound effects on cerebral blood flow and on autoregulation. If PaCO2 is maintained at 40 mm Hg after correction for temperature, autoregulation is abolished. If uncorrected PaCO2 is maintained at approximately 40 mm Hg, some degree of autoregulation is preserved, albeit with a right-shifted "knee."
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A patent foramen ovale has been reported to be significantly more frequent in young stroke patients than in matched control subjects, and paradoxical embolism has been suggested as the main mechanism of stroke in this situation. The present study was designed to test this hypothesis. ⋯ Our results do not support the hypothesis that paradoxical embolism is the primary mechanism of stroke in patients with a patent foramen ovale.
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Comparative Study
Cerebral blood flow velocity after hyperventilation-induced vasoconstriction in hypertensive patients.
The aim of our study was to evaluate by transcranial Doppler ultrasonography the dynamics of blood flow velocity changes in the middle cerebral artery during and after hypocapnia-induced vasoconstriction in untreated essential hypertensive patients. ⋯ This study demonstrates that the recovery of blood flow velocity in the middle cerebral artery after hyperventilation is faster in hypertensive patients than in normal subjects, thus providing further evidence that chronic hypertension is associated with changes in the dynamics of cerebral blood vessel reactivity.