Stroke; a journal of cerebral circulation
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Significant delays often occur during the treatment of patients with acute stroke. Some of those delays occur in the hospital. We attempted to shorten inhospital treatment intervals by creating a rapid-response system, similar to that available for cardiac arrest, that would allow the stroke team to be available within a few minutes to care for stroke victims. ⋯ It is possible to shorten inhospital treatment delays by instituting rapid-response systems within individual institutions.
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The purpose of this study was to evaluate the use of velocity criteria applied to transcranial Doppler (TCD) signals in the detection of stenosis of the middle cerebral (MCA), distal vertebral, and basilar arteries. ⋯ TCD may be an effective screening test for M1 stenosis when velocity criteria alone are used. TCD may less reliably detect intracranial vertebral and basilar artery stenosis.
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Calcium channel blockers reduce edema due to cerebral ischemia, but little is known about their usefulness in hemorrhage. Therefore, we studied the effect of the calcium channel blocker (S)-emopamil in collagenase-induced hemorrhage. ⋯ Early administration of (S)-emopamil is beneficial in hemorrhagic lesions, but a subsequent delayed injection may be deleterious. Knowledge of the time of hemorrhage will be important in use of these agents in treating hemorrhage.
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Beneficial effects of calcium antagonists in cerebral ischemia and trauma have been attributed in part to improved cerebral blood flow. Enhancement of cerebral blood flow, however, could aggravate the pathological situation if brain injury is associated with intracerebral hemorrhage. In this study we used high-field magnetic resonance imaging in an animal model of intracerebral hemorrhage to determine noninvasively the effect of the calcium and serotonin antagonist levemopamil [international nonproprietary name for (S)-emopamil] when infused in a dose (6 mg/kg) that is known to increase cerebral blood flow. ⋯ Aggravation of intracerebral hemorrhage was not observed by magnetic resonance imaging in levemopamil-infused animals. However, infusion of heparin caused a significant (P < .05), almost twofold increase in the size of intracerebral hemorrhage. These results justify clinical trials with levemopamil in cerebral disorders such as stroke, brain trauma, and peritumoral brain edema, which may be accompanied by intracerebral hemorrhage from the beginning or where transition to intracerebral hemorrhage may occur.
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Comparative Study
Mechanisms of vasodilation of cerebral vessels induced by the potassium channel opener nicorandil in canine in vivo experiments.
Nicorandil, a potent antianginal agent characterized as a potassium channel opener, could produce cerebrovascular dilation in in vitro studies. Our aim was to investigate the pharmacologic response to the topical application of nicorandil on the vasomotor tone of pial vessels in vivo. To elucidate its mechanism, we also studied the inhibitory action of methylene blue and glibenclamide against nicorandil-induced vasodilation. ⋯ Our in vivo study demonstrates that topical application of nicorandil dilates both pial arterioles and venules in a concentration-dependent manner and suggests that the mechanisms of such actions are most likely due to both cyclic GMP-mediated vascular smooth muscle dilation and the regulation of K+ flux.