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Cerebral Circulation (cerebral + circulation)
Selected AbstractsIs It Safe to Initiate Selective Cerebral Perfusion with Normothermia?JOURNAL OF CARDIAC SURGERY, Issue 5 2005Mizuho Imamaki M.D. Cerebral circulation is isolated from systemic circulation to avoid cerebral embolization due to detachment of atherosclerotic material from the aorta, caused by the "sandblasting" effect of high-velocity jets of blood exiting the aortic cannula. However, neither the safety of SCP at normothermia nor the influence of extended SCP time has been sufficiently clarified. To clarify the safety of P-SCP, the comparison study of P-SCP and conventional SCP (C-SCP) was performed retrospectively. Methods: Fifty-seven patients (C-SCP group: 29 patients; P-SCP: 28 patients) underwent surgery between 1992 and 2002. Results: Nine (15.8%) in-hospital death occurred; 4 in the C-SCP group (13.8%) and 5 in the P-SCP group (17.9%) (NS). The SCP time was 136.6 ± 68.5 minutes in the C-SCP group and 195.8 ± 30.7 minutes in the P-SCP group (p < 0.05). One patient in each group exhibited postoperative neurological dysfunction. Conclusion: It may be little dangerous to initiate the SCP with normothermia. P-SCP may be useful in cases in which there is pedunculated atherosclerotic material, or mural thrombus in the ascending and arch aorta. [source] Twenty-four-hour non-invasive monitoring of systemic haemodynamics and cerebral blood flow velocity in healthy humansACTA PHYSIOLOGICA, Issue 1 2002M. DIAMANT ABSTRACT Acute short-term changes in blood pressure (BP) and cardiac output (CO) affect cerebral blood flow (CBF) in healthy subjects. As yet, however, we do not know how spontaneous fluctuations in BP and CO influence cerebral circulation throughout 24 h. We performed simultaneous monitoring of BP, systemic haemodynamic parameters and blood flow velocity in the middle cerebral artery (MCAV) in seven healthy subjects during a 24-h period. Finger BP was recorded continuously during 24 h by Portapres and bilateral MCAV was measured by transcranial Doppler (TCD) during the first 15 min of every hour. The subjects remained supine during TCD recordings and during the night, otherwise they were seated upright in bed. Stroke volume (SV), CO and total peripheral resistance (TPR) were determined by Modelflow analysis. The 15 min mean value of each parameter was assumed to represent the mean of the corresponding hour. There were no significant differences between right vs. left, nor between mean daytime vs. night time MCAV. Intrasubject comparison of the twenty-four 15-min MCAV recordings showed marked variations (P < 0.001). Within each single 15-min recording period, however, MCAV was stable whereas BP showed significant short-term variations (P < 0.01). A day,night difference in BP was only observed when daytime BP was evaluated from recordings in the seated position (P < 0.02), not in supine recordings. Throughout 24 h, MCAV was associated with SV and CO (P < 0.001), to a lesser extent with mean arterial pressure (MAP; P < 0.005), not with heart rate (HR) or TPR. These results indicate that in healthy subjects MCAV remains stable when measured under constant supine conditions but shows significant variations throughout 24 h because of activity. Moreover, changes in SV and CO, and to a lesser extent BP variations, affect MCAV throughout 24 h. [source] Statin administration prior to ischaemic stroke onset and survival: exploratory evidence from matched treatment,control studyEUROPEAN JOURNAL OF NEUROLOGY, Issue 7 2005S. Aslanyan In addition to their lipid-lowering effects, it has been speculated that statins may also have beneficial effects on cerebral circulation and brain parenchyma during ischaemic stroke and reperfusion. We hypothesized that patients who had taken statins prior to stroke onset may have a better survival rate at 1 month and during the follow-up period. We retrospectively studied consecutive ischaemic stroke patients admitted to an acute stroke unit and at least a month's follow-up. From these, we included those patients who, at admission, had reported the use of a statin prior to the stroke onset in the statin group (n = 205). Each patient in the statin group was matched with two patients who reported no statin use (n = 410). Using logistic regression and Cox proportional hazards models, we adjusted for variables that significantly differed between treatment groups or that independently predicted mortality. After adjusting for those variables, statin use was associated with reduced mortality at 1 month [odds ratio 0.24; 95% confidence interval (CI) 0.09,0.67] and during the follow-up period (hazard ratio 0.57; 95% CI 0.35,0.93). The use of statins prior to stroke onset is associated with improved stroke survival within this cohort study with matched controls. [source] Neurophysiological tests and neuroimaging procedures in non-acute headache: guidelines and recommendationsEUROPEAN JOURNAL OF NEUROLOGY, Issue 4 2004G. Sandrini The use of instrumental examinations in headache patients varies widely. In order to evaluate their usefulness, the most common instrumental procedures were evaluated, on the basis of evidence from the literature, by an EFNS Task Force (TF) on neurophysiological tests and imaging procedures in non-acute headache patients. The conclusions of the TF regarding each technique are expressed in the following guidelines for clinical use. 1Interictal electroencephalography (EEG) is not routinely indicated in the diagnostic evaluation of headache patients. Interictal EEG is, however, indicated if the clinical history suggests a possible diagnosis of epilepsy (differential diagnosis). Ictal EEG could be useful in certain patients suffering from hemiplegic and basilar migraine. 2Recording of evoked potentials is not recommended for the diagnosis of headache disorders. 3There is no evidence to justify the recommendation of autonomic tests for the routine clinical examination of headache patients. 4Manual palpation of pericranial muscles, with standardized palpation pressure, can be recommended for subdividing patient groups but not for diagnosis. Pressure algometry and electromyography (EMG) cannot be recommended as clinical diagnostic tests. 5In adult and paediatric patients with migraine, with no recent change in attack pattern, no history of seizures, and no other focal neurological signs or symptoms, the routine use of neuroimaging is not warranted. In patients with atypical headache patterns, a history of seizures and/or focal neurological signs or symptoms, magnetic resonance imaging (MRI) may be indicated. 6If attacks can be fully accounted for by the standard headache classification [International Headache Society (IHS)], a positron emission tomography (PET) or single-photon emission computerized tomography (SPECT) and scan will generally be of no further diagnostic value. 7Nuclear medicine examinations of the cerebral circulation and metabolism can be carried out in subgroups of headache patients for diagnosis and evaluation of complications, when patients experience unusually severe attacks, or when the quality or severity of attacks has changed. 8Transcranial Doppler examination is not helpful in headache diagnosis. Although many of the examinations described are of little or no value in the clinical setting, most of the tools have a vast potential for further exploring the pathophysiology of headaches and the effects of pharmacological treatment. [source] Changes in Cerebral Blood Flow During and After 48 H of Both Isocapnic and Poikilocapnic Hypoxia in HumansEXPERIMENTAL PHYSIOLOGY, Issue 5 2002Marc J. Poulin During acclimatization to the hypoxia of altitude, the cerebral circulation is exposed to arterial hypoxia and hypocapnia, two stimuli with opposing influences on cerebral blood flow (CBF). In order to understand the resultant changes in CBF, this study examined the responses of CBF during a period of constant mild hypoxia both with and without concomitant regulation of arterial PCO2. Nine subjects were each exposed to two protocols in a purpose-built chamber: (1) 48 h of isocapnic hypoxia (Protocol I), where end-tidal PO2 (PET,O2) was held at 60 Torr and end-tidal PCO2 (PET,CO2) at the subject's resting value prior to experimentation; and (2) 48 h of poikilocapnic hypoxia (Protocol P), where PET,O2 was held at 60 Torr and PET,CO2 was uncontrolled. Transcranial Doppler ultrasound was used to assess CBF. At 24 h intervals during and after the hypoxic exposure CBF was measured and the sensitivity of CBF to acute variations in PO2 and PCO2 was determined. During Protocol P, PET,CO2 decreased by 13% (P < 0.001) and CBF decreased by 6% (P < 0.05), whereas during Protocol I, PET,CO2 and CBF remained unchanged. The sensitivity of CBF to acute variations in PO2 and PCO2 increased by 103% (P < 0.001) and 28% (P < 0.01), respectively, over the 48 h period of hypoxia. These changes did not differ between protocols. In conclusion, CBF decreases during mild poikilocapnic hypoxia, indicating that there is a predominant effect on CBF of the associated arterial hypocapnia. This fall occurs despite increases in the sensitivity of CBF to acute variations in PO2/PCO2 arising directly from the hypoxic exposure. [source] Cerebral emboli and paradoxical embolisation in dementia: a pilot studyINTERNATIONAL JOURNAL OF GERIATRIC PSYCHIATRY, Issue 1 2005Nitin Purandare Abstract Background The causes of the common dementias remain unknown. Paradoxical embolisation of the cerebral circulation by venous thrombi passing through venous to arterial shunts (v-aCS) in the heart or pulmonary circulation is known to occur in cryptogenic stroke and post-operative confusion following hip replacement. Objectives To explore the role of paradoxical embolisation in dementia by investigating for cerebral emboli, venous to arterial circulation shunt (v-aCS) and carotid artery disease. Methods Forty-one patients with dementia (24 Alzheimer's AD and 17 vascular VaD) diagnosed using DSM-IV criteria and 16 controls underwent transcranial Doppler (TCD) detection of spontaneous cerebral emboli in both middle cerebral arteries. A v-aCS was detected by intravenous injection of an air/saline ultrasound contrast at rest and after provocation by coughing and Valsalva's manoeuvre. Carotid artery disease was assessed by duplex imaging. Results Cerebral emboli were detected in 11 (27.5%) dementia patients compared with one (7%) control (p,=,0.15) with emboli being most frequent in VaD (41%) compared to controls [OR (95% CI): 10.5 (1.1, 98.9), p,=,0.04]. A v-aCS was detected in 25 (61%) patients and seven (44%) controls (p,=,0.24). In dementia patients with cerebral emboli; v-aCS was detected in seven (64%) and moderate to severe carotid stenosis was present in three (30%). Conclusion Cerebral emboli and v-aCS may be more frequent in patients with both VaD and AD than in controls, which suggest paradoxical embolisation as a potential mechanism for cerebral damage. This pilot study justifies a definitive case-control study. Copyright © 2004 John Wiley & Sons, Ltd. [source] Implantation of Bilateral Carotid Artery Filters to Allow Safe Removal of Left Atrial Thrombus During Ablation of Atrial FibrillationJOURNAL OF CARDIOVASCULAR ELECTROPHYSIOLOGY, Issue 10 2006SILVIA MARTELO M.D. Left atrial clot formation is a feared complication of catheter ablation for atrial fibrillation. We report a case of left atrial thrombus that formed around the circular mapping catheter before the delivery of RF. Successful retrieval of the clot was obtained by withdrawing the catheters while protecting the anterior cerebral circulation by positioning temporary carotid artery filters. [source] Accuracy of transcranial Doppler sonography for predicting cerebral infarction in aneurysmal subarachnoid hemorrhageJOURNAL OF CLINICAL ULTRASOUND, Issue 8 2006Ji-Yong Lee MD Abstract Purpose. To evaluate the accuracy of transcranial Doppler (TCD) sonography using different criteria for predicting cerebral infarction due to symptomatic vasospasm. Methods. We retrospectively evaluated the clinical and radiologic data of consecutive patients admitted with acute aneurysmal subarachnoid hemorrhage (SAH) in the anterior cerebral circulation between January 2001 and June 2002. TCD sonographic examinations were performed on alternate days up to 20 days after admission. Cerebral infarction was defined on CT as a new hypodensity in the vascular distribution with corresponding clinical symptoms. Vasospasm was diagnosed as mild or severe when TCD sonography revealed a mean blood flow velocity (MBFV) greater than 120 and 180 cm/s in the middle or anterior cerebral artery and in the intracranial part of the internal carotid artery, respectively. Results. A total of 93 patients with aneurysmal SAH in the anterior cerebral circulation were included. Vasospasm was demonstrated by TCD sonography in 60 patients (64.5%) and was shown via multivariable logistic regression analysis to be predictive of cerebral infarction (OR 3.11, 95% CI 1.46,6.59), with an 82.6% and 69.6% sensitivity, a 41.4% and 77.1% specificity, a 31.7% and 50.0% positive predictive value, and an 87.9% and 88.5% negative predictive value when the MBFV was greater than 120 and 180 cm/s, respectively. Conclusions. Vasospasm on TCD was found to be predictive of symptomatic cerebral infarction on CT, but its positive predictive value remained low despite the adoption of restrictive TCD criteria for vasospasm. © 2006 Wiley Periodicals, Inc. J Clin Ultrasound 34:380,384, 2006 [source] What's New in the Cerebral Microcirculation?MICROCIRCULATION, Issue 6 2001DONALD D. HEISTAD ABSTRACT The first part of this paper focuses on unusual aspects of the cerebral circulation. Cerebral vessels have less smooth muscle and adventitia than other vessels, and the endothelial blood-brain barrier is unique. Because the wall of the arteries is thin, one might expect that the vessels are especially vulnerable to rupture. Pressure in intracranial arteries, however, is lower than in other arteries, because resistance of larger cerebral arteries is remarkably high. The low pressure in cerebral arteries presumably protects against rupture of the vessels. The second part of the paper summarizes some new insights into regulation of cerebral circulation. One concept is that "breakthrough" of autoregulation, with dilatation of cerebral vessels at high levels of pressure, is an active process, rather than a passive phenomenon. This conclusion is based on the finding that inhibitors of calcium-dependent potassium channels greatly attenuate the cerebral vasodilator response during acute hypertension. The third part of the paper focuses on effects of gene transfer to cerebral blood vessels. Gene transfer to intracranial and extracranial vessels is feasible and vasomotor function can be altered. Gene transfer has proven to be useful to study vascular biology, and we are optimistic that the approach will ultimately lead to gene therapy. [source] Autoregulation of the cerebral circulation during sleep in newborn lambsTHE JOURNAL OF PHYSIOLOGY, Issue 3 2005Daniel A. Grant Autoregulation is a vital protective mechanism that maintains stable cerebral blood flow as cerebral perfusion pressure changes. We contrasted cerebral autoregulation across sleep,wake states, as little is known about its effectiveness during sleep. Newborn lambs (n= 9) were instrumented to measure cerebral blood flow (flow probe on the superior sagittal sinus) and cerebral perfusion pressure, then studied during active sleep (AS), quiet sleep (QS) and quiet wakefulness (QW). We generated cerebral autoregulation curves by inflating an occluder cuff around the brachiocephalic artery thereby lowering cerebral perfusion pressure. Baseline cerebral blood flow was higher (P < 0.05) and cerebral vascular resistance lower (P < 0.05) in AS than in QW (76 ± 8% and 133 ± 15%, respectively, of the AS value, mean ±s.d.) and in QS (66 ± 11% and 158 ± 30%). The autoregulation curve in AS differed from that in QS and QW in three key respects: firstly, the plateau was elevated relative to QS and QW (P < 0.05); secondly, the lower limit of the curve (breakpoint) was higher (P < 0.05) in AS (50 mmHg) than QS (45 mmHg); and thirdly, the slope of the descending limb below the breakpoint was greater (P < 0.05) in AS than QS (56% of AS) or QW (56% of AS). Although autoregulation functions in AS, the higher breakpoint and greater slope of the descending limb may place the brain at risk for vascular compromise should hypotension occur. [source] Management of Neck Metastasis with Carotid Artery Involvement,THE LARYNGOSCOPE, Issue 1 2004Stephen B. Freeman MD Abstract Objectives To demonstrate aggressive management of neck metastasis adherent to the internal or common carotid artery using sound oncologic principles while minimizing the significant risk of complications. Study Design Our 13 year experience of treating patients with recurrent or residual neck metastasis adherent to the internal or common carotid artery was retrospectively reviewed. Methods Angiography was used in patients who demonstrated fixation of the carotid artery on examination or imaging, followed by balloon test occlusion and single photon emission computer tomography (SPECT) scanning. The majority of carotid resections were reconstructed with a vein graft, especially if there was insufficient collateral cerebral circulation. Radical resection of the soft tissue including the carotid artery was performed followed by 15 to 20 Gray of electron beam delivered directly to the deep tissue. More recently, the carotid has been permanently occluded preoperatively, if possible. The assessment of the cerebral circulation and management of the carotid artery were analyzed as was survival, site of recurrence, and complications. Results Fifty-eight charts were reviewed. The majority of patients (41) had their carotid artery reconstructed at time of resection, and the remaining had either the artery ligated or permanently occluded preoperatively. Strokes occurred in 11 patients. The median disease-specific survival was 12 months, with 24% of patients dying from distant metastasis. Conclusions The high risk of complications, loss of life's quality, and mortality must be balanced against the natural history of the disease if left untreated. The decision is a heavy burden for the patient, family, and head and neck surgeon. [source] Clinical Real-Time Monitoring of Gaseous Microemboli in Pediatric Cardiopulmonary BypassARTIFICIAL ORGANS, Issue 11 2009Shigang Wang Abstract We describe the occurrence and distribution of gaseous microemboli with real-time monitoring in a pediatric cardiopulmonary bypass (CPB) circuit and in the cerebral circulation of patients using the Emboli Detection and Classification (EDAC) system and transcranial Doppler (TCD). Four patients (weights 3.2,13.8 kg) were studied. EDAC monitors were located on the venous line and on the postfilter arterial line to measure gaseous microemboli in the CPB circuit. TCD was used to measure high-intensity transient signals (HITS) in the middle cerebral artery. Before the initiation of CPB, EDAC detected gaseous microemboli in two cases when giving volume through the arterial line. At the initiation of CPB, gross air appeared in the venous line and gaseous microemboli were detected in the arterial line in all patients. EDAC detected a total of 3192,14 699 gaseous microemboli in the arterial line during the whole CPB period, more than 99% of which were smaller than 40 microns. After cessation of CPB, EDAC detected gaseous microemboli in the arterial line in all cases. The TCD detected HITS in two cases (25 and 315), and detected no HITS in two cases. We observed that the venous line acted as a principal source of gaseous microemboli, particularly when using vacuum-assisted venous drainage, and that a significant number of these gaseous microemboli smaller than 40 microns were subsequently transferred to the patient. Using EDAC and TCD together could strengthen the monitoring of gaseous microemboli in the extracorporeal circuit and cerebral circulation. [source] Cerebral Tissue Oxygen Saturation During Percutaneous Cardiopulmonary Support in a Canine Model of Respiratory FailureARTIFICIAL ORGANS, Issue 8 2000Hideichi Wada Abstract: Percutaneous cardiopulmonary support (PCPS) has come to be applied for cardiopulmonary resuscitation and in the management of severe respiratory failure as well as severe heart failure. We investigated cerebral tissue oxygen saturation during PCPS in a canine model of respiratory failure using near-infrared spectroscopy. Animals were mechanically ventilated with 10% oxygen to make a respiratory failure model. Perfusion with PCPS was performed via the left femoral artery and switched to that via the right axillary artery. Cerebral tissue oxygen saturation was 54.2 ± 3.4% during PCPS via the femoral artery and was 82.3 ± 4.6% during PCPS via the axillary artery (p = 0.001). Hepatic tissue oxygen saturation was not significantly different. LV dP/dt max increased significantly after switching to the axillary blood supply (p = 0.001). Conventional PCPS may not have the capability of supporting cerebral circulation under severe respiratory failure without organic heart disease. [source] Importance of calcitonin gene-related peptide, adenosine and reactive oxygen species in cerebral autoregulation under normal and diseased conditionsCLINICAL AND EXPERIMENTAL PHARMACOLOGY AND PHYSIOLOGY, Issue 1-2 2004Hwa Kyoung Shin Summary 1.,Mechanisms regulating cerebral circulation, including autoregulation of cerebral blood flow (CBF), have been widely investigated. Vasodilators such as nitric oxide, prostacyclin, calcitonin gene-related peptide (CGRP) and K+ channel openers are well known to have important roles in the physiological and pathophysiological control of CBF autoregulation. In the present review, the focus is on the mechanism(s) of altered CBF autoregulation after traumatic brain injury and subarachnoid haemorrhage (SAH) and on the effect of adenovirus-mediated transfer of Cu/Zn superoxide dismutase (SOD)-1 in amelioration of impaired CBF autoregulation. 2.,The roles of CGRP and adenosine are particularly emphasized, both being implicated in the autoregulatory vasodilation of the pial artery in response to hypotension. 3.,After fluid percussion injury, production of NADPH oxidase-derived superoxide anion and activation of tyrosine kinase links the inhibition of K+ channels to impaired autoregulatory vasodilation in response to acute hypotension and alterations in CBF autoregulation in rat pial artery. 4.,Subarachnoid haemorrhage during the acute stage causes an increase in NADPH oxidase-dependent superoxide formation in cerebral vessels in association with activated tyrosine phosphorylation-coupled increased expression of gp91phox mRNA and membrane translocation of Rac protein, thereby resulting in a significant reduction of autoregulatory vasodilation. 5.,Fluid percussion injury and SAH-induced overproduction of superoxide anion in cerebral vessels contributes to the impairment of CBF autoregulation and administration of recombinant adenovirus-mediated transfer of the Cu/Zn SOD-1 gene effectively ameliorates the impairment of CBF autoregulation of the pial artery. [source] Forensic Considerations in Cases of Neurofibromatosis,An OverviewJOURNAL OF FORENSIC SCIENCES, Issue 5 2007Roger W. Byard M.B.B.S. Abstract:, Neurofibromatosis types 1 and 2 are inherited neurocutaneous disorders characterized by a variety of manifestations that involve the circulatory system, the central and peripheral nervous systems, the skin, and the skeleton. Significant reduction in lifespan occurs in both conditions often related to complications of malignancy and hypertension. Individuals with these conditions may also be the subject of medicolegal autopsy investigation if sudden death occurs. Unexpected lethal events may be associated with intracranial neoplasia and hemorrhage or brainstem compression. Vasculopathy with fibrointimal proliferation may result in critical reduction in blood flow within the coronary or cerebral circulations, and aneurysmal dilatation may be associated with rupture and life-threatening hemorrhage. An autopsy approach to potential cases should include review of the history/hospital record, liaison with a clinical geneticist (to include family follow-up), a full external examination with careful documentation of skin lesions and nodules, measurement of the head circumference in children, photography, possible radiologic examination, a standard internal autopsy examination, documentation of the effects of previous surgery and/or chemo/radiotherapy, examination for specific tumors, specific examination and sampling of vasculature (renal, cerebral, and cardiac), formal neuropathologic examination of brain and spinal cord, possible examination of the eyeballs, examination of the gastrointestinal tract, histology to include tumors, vessels, gut, and bone marrow, toxicological testing for anticonvulsants, and sampling of blood and tissue for possible cytogenetic/molecular evaluation if required. [source] | |||||||||||||