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At least 145 records · Page 8Linked to original sources
PubMed1989

[Nimodipine and cerebrovascular circulation. Initial results apropos of 4 cases of subarachnoid hemorrhage].

Nimodipine was included in the treatment of four patients who had previously presented subarachnoid hemorrhage; cerebral circulation has been assayed by means of "Tomophygmographie cérébrale ultra-sonore". In all four patients, use of Nimodipine has led to an improvement of cerebral circulation and then of the neurological status. Nimodipine is characterized by its very low therapeutic inertion. Data obtained both at the initiation and on interruption of the administration of this drug points to its original properties regarding cerebral circulation: indeed, the present observations suggest that Nimodipine behaves as a true vasoregulator.

Cerebrovascular Circulation↗
PubMed2006

Carbon monoxide and hydrogen sulfide: gaseous messengers in cerebrovascular circulation.

This review focuses on two gaseous cellular messenger molecules, CO and H2S, that are involved in cerebrovascular flow regulation. CO is a dilatory mediator in active hyperemia, autoregulation, hypoxic dilation, and counteracting vasoconstriction. It is produced from heme by a constitutively expressed enzyme [heme oxygenase (HO)-2] expressed highly in the brain and by an inducible enzyme (HO-1). CO production is regulated by controlling substrate availability, HO-2 catalytic activity, and HO-1 expression. CO dilates arterioles by binding to heme that is bound to large-conductance Ca2+-activated K+ channels. This binding elevates channel Ca2+ sensitivity, that increases coupling of Ca2+ sparks to large-conductance Ca2+-activated K+ channel openings and, thereby, hyperpolarizes the vascular smooth muscle. In addition to dilating blood vessels, CO can either inhibit or accentuate vascular cell proliferation and apoptosis, depending on conditions. H2S may also function as a cerebrovascular dilator. It is produced in vascular smooth muscle cells by hydrolysis of l-cysteine catalyzed by cystathione gamma-lyase (CSE). H2S dilates arterioles at physiologically relevant concentrations via activation of ATP-sensitive K+ channels. In addition to dilating blood vessels, H2S promotes apoptosis of vascular smooth muscle cells and inhibits proliferation-associated vascular remodeling. Thus both CO and H2S modulate the function and the structure of circulatory system. Both the HO-CO and CSE-H2S systems have potential to interact with NO and prostanoids in the cerebral circulation. Much of the physiology and biochemistry of HO-CO and CSE-H2S in the cerebral circulation remains open for exploration.

Animals↗
PubMed1992

[Cerebrovascular circulation in patients with oligomenorrhea].

Brain hemodynamics was studied in 76 patients with oligomenorrhea aged 18 to 35 from the data of rheoencephalography. Disorders of the regional tone of brain vessels were different and related to the time of the menstrual cycle disorder; this may be explained by the degree of changes in various neuromediator mechanisms of brain circulation and reproductive system function regulation.

Adolescent↗
PubMedDate not supplied

[Modelling cerebrovascular circulation from the viewpoint of autoregulation mechanisms].

The rationale for cerebral blood flow modelling is to extrapolate the possible effects of the pharmacological agents and significance of different pathologic states. Most authors present linear, statistical models. Such modelling does not take into consideration many important factors. Autoregulation of cerebral circulation is the most important one. It maintains cerebral blood flow on a constant level despite significant changes of systemic pressure. Influence of autoregulation is necessary for evaluation of the different anatomical configurations of the main supplying arteries and the cerebral arterial circle of Willis. This paper presents original, non-linear and dynamic model of the cerebral circulation with factor of autoregulation. Comparison of the data from the modelling and from the clinical observations shows high correlation.

Blood Pressure↗
PubMed2000

The effect of low concentrations of halothane on the cerebrovascular circulation in young children.

To determine the effect of halothane on cerebral blood flow velocity measured by transcranial Doppler, 23 healthy young children were studied during surgery. Anaesthesia was induced with thiopental, fentanyl and vecuronium, and maintained with halothane in 70% nitrous oxide in oxygen. A continuous epidural anaesthesia with 0. 25% bupivacaine was performed. End-tidal carbon dioxide pressure, temperature, heart rate and systolic blood pressure were kept constant. Three minimal alveolar concentrations (MAC; 0.5, 1.0 and 1. 5) of halothane were administered in stepwise increases. The cerebral blood flow velocity increased significantly at 1.0 (p < 0. 01) and 1.5 MAC (p < 0.001) compared with the value at 0.5 MAC. No further change in cerebral blood flow velocity was seen between 1.0 and 1.5 MAC. These data show that maximal changes in cerebral blood flow velocity are obtained at 1.0 MAC and that further increases in halothane concentration do not modify the cerebral circulation. It is suggested that young children differ from adults in that the maximal effect of halothane occurs at lower concentrations.

Anesthetics, Inhalation↗
PubMed1990

[Hemodynamic assessment of cerebrovascular circulation using transcranial Doppler ultrasound in patients with carotid stenosis].

Transcranial Doppler-ultrasound (TCD) is a new non-invasive technique which renders continuous monitoring of the rate of flow in the major intracerebral arteries possible. The method appears, therefore, to be attractive for perioperative monitoring of patients submitted to operation on account of carotid stenosis. Seventeen patients were included in this preliminary investigation. These patients were submitted for thromboarterectomy of the internal carotid artery. Preoperatively the average flow rate (Vmean) in the ipsilateral medial cerebral artery measured at rest was 54 cm/second (range 34-94) as compared with 57 cm/second (range 32-86) in the contralateral medial cerebral artery. During occlusion, Vmean in the ipsilateral medial cerebral artery decreased momentarily, on an average 35% (p less than 0.001), and returned to the preoperative level after reopening of the internal carotid artery. Corresponding but no significant changes were observed in the pulsatile index. The preliminary experience suggests that TCD is scarcely useful as a diagnostic method in individual cases but that it is well suited for continuous monitoring of changes in cerebral circulating during surgery on the internal cerebral artery. Further assessment of the technique is necessary before the method can be employed routinely, mainly on account of the great interindividual scatter.

Aged↗
PubMed1978

[The effect of pyritinol on the human cerebrovascular circulation (author's transl)].

The change in global and regional cerebral circulation after intravenous administration of pyritinol was investigated in 14 patients with acute or subchronic cerebral ischemia. The measurement of the cerebral circulation was performed by intraarterial isotope clearance with 133xenon using a multidetector apparatus. With a single administration of pyritinol (400 mg) there was a statistically significant increase in the cerebral circulation in the gray matter by 6.7 ml/100 g/min corresponding to 9.7% (p less than 0.01) 10 minutes after the end of the drug injection. In the areas of all portions of the brain with defective circulation there was a significant increase in blood flow by 8.9, 0.8 and 3.2 ml/100 g/min (gray matter, white matter, total substance), corresponding to 12.3%, 4.4% and 8.1%. In areas with a normal initial status, the increase in blood flow attained statistical significance in the gray matter only (p less than 0.05).

Brain Ischemia↗
PubMed1989

[Effect of calcium antagonists on cerebral and systemic hemodynamics in patients with ischemic disorders of cerebrovascular circulation].

Doppler ultrasound and Evans blue dilution techniques were applied to investigate the corinfar and finoptin effects on cerebral circulation in 97 patients, and on regional circulation in 40 patients with cerebral ischemia. In patients with severe ischemic brain damage, the vasodilating effect without intracerebral stealing was most pronounced. Cardiodepressant effects were negligible. The authors discuss indications and contraindications to finoptin and corinfar treatment in ischemic brain disorders.

Adult↗
PubMed1990

[Effects of trihexyphenidyl on basilar artery of rabbits and cerebrovascular circulation of rats].

Trihexyphenidyl (Tri) inhibited the contraction of rabbit basilar artery due to high K+ (45.6 mmol/L). IC50 was 2.9 +/- 0.7 mumol/L. The contractions of basilar and mesenteric arteries due to calcium and those of basilar artery and saphenous vein due to serotonin were noncompetitively. Tri inhibited myogenic activities of the portal vein strips of rats and increased the normal cerebral blood flow of rats to 19 +/- 7 ml/(min.100 g).

Animals↗
PubMed1989

[Duplex and transcranial sonography in the preoperative evaluation of cerebrovascular circulation before heart operations].

Fifty unselected patients undergoing open heart surgery (OHS) were examined by duplex and transcranial Doppler sonography. Two high degree (greater than 75%) carotid stenosis were found in 70 carotid arteries of 35 patients with coronary artery disease. Fourteen vessels had unmistakable signs of extracranial vascular disease whilst 54 carotid arteries were identified as normal. Two high degree (greater than 75%) carotid stenosis were found in 30 vessels of 15 patients with valvular disease. Seven other vessels had a low grade stenosis or excessive atheroma, whereas 21 were identified as normal. The rate of about 5-10% asymptomatic high grade carotid stenosis in patients undergoing OHS justifies routine noninvasive examination of the cerebral circulation by duplex and transcranial Doppler sonography. Patients with high grade stenosis are offered a follow-up preventive programme against cerebral infarction, which consists of 3 steps: 1. anti-platelet aggregating drugs, 2. periodic control examinations by duplex and transcranial Doppler sonography, and 3. continued evaluation of indication for carotid endarterectomy.

Adult↗
PubMed2000

[Cerebrovascular circulation during blockade of angiotensin receptors].

In experiments on anaesthetized rats, Losartan was found to cause an obvious decrease in the ABP in normotensive rats. The cerebral blood flow differed independence on cerebral vascular resistance and the ABP level. The autoregulation of the cerebral blood flow remained unaltered. In hypertensive rats Losartan caused a significant decrease in the ABP as compared with normotensive rats. A shift of lower limits of the cerebral blood flow autoregulation towards a lower ABP level, was observed.

Angiotensin Receptor Antagonists↗
PubMed1987

[Does the capacity for autoregulation of cerebrovascular circulation depend on gestational age?].

Changes of blood velocity in the right internal carotid artery (measured by transfontanellar pulsed Doppler) in relation to therapeutically induced changes of mean arterial blood pressure (measured oscillometrically) were used to evaluate autoregulatory capacity of cerebral blood flow in 17 neonates (540-3800 g). Preterm infants less than 32 gestational weeks (n = 11) didn't autoregulate, while the capacity of autoregulation was significantly better in neonates greater than 31 gestational weeks (n = 6). Regarding their disturbed autoregulation there was no difference between normotensive (n = 4) and hypotensive (n = 7) preterm infants less than 32 gestational weeks.

Blood Flow Velocity↗
PubMed1995

[Doppler ultrasound of the middle cerebral artery: pre-final normalization of cerebrovascular circulation?].

We report on the circulatory changes of a severely growth-retarded fetus at 26 weeks of gestation with intrauterine death after 6 days of observation and a birth weight of 480 g. On admission the fetus already showed signs of circulatory centralisation; furthermore, we found pulsation in the umbilical vein and diastolic reverse flow in the umbilical artery. During the days of observation this reverse flow increased and the compensatory phase of fetal circulatory centralisation was followed on the last day by a phase of circulatory decompensation with an apparently normal middle cerebral artery waveform, mimicking preterminal normalisation of fetal cerebral blood flow.

Adult↗