BACKGROUND AND PURPOSE: Near-infrared spectroscopy (NIRS) derives information about the concentrations of oxyhemoglobin (HbO2) and deoxyhemoglobin (Hb) from measurements of light attenuation caused by these chromosphores. The aim of this study was to assess NIRS as a tool for testing CO2 reactivity in patients with carotid artery disease. METHODS: One ...

Ultrasound measurement of volume blood flow is potentially useful for many clinical situations, yet practical implementation and use are restricted by the many instrumentation and blood flow limitations that can arise. Colour velocity imaging offers a number of theoretical advantages over methods based on duplex imaging. We evaluated a colour ...

Blood flow was measured in the common carotid artery (CCA) and the vertebral artery (VA) by the ultrasonic Doppler method in 14 male patients with sudden deafness and 70 normal adults. In the patients, blood flow on the affected side was slower than that on the normal side or that ...

Blood pressure and blood flow patterns were recorded from the carotid artery and aortae of a thick-bodied terrestrial snake (Crotalus adamanteus) and a thin-bodied arboreal species (Ahaetulla nasuta) anesthetized with ketamine hydrochloride. Hemodynamic stress induced by rotation resulted in pronounced changes in the blood flow patterns and pressure in C. ...

Scholz and co-workers reported such type of anastomosis applied in femoro-crural bypass procedures which leads blood flow well into both directions. In vascular surgery practice of the author there were several occasions where this modified anastomosis was favorably applicable. An old man was operated up in this manner whose left ...

This study was performed to answer the question of whether counter current retrograde transfer of beta-endorphin in the perihypophyseal cavernous sinus-carotid rete vascular complex depends on the reproductive activity of sheep and if this transfer depends on membrane Na+ K+ ATP-ase blocking by ouabain. Sheep were anaesthetised and the jugular ...

The present study investigated the mechanism of diving bradycardia. A group of 14 healthy untrained male subjects were examined during breath-holding either out of the water (30-33 degrees C), in heat-out immersion, or in whole-body submersion (27-29 degrees C) in a diving pool. Blood velocity, blood volume flow in the ...

Recurrent stenosis because of myointimal hyperplasia or atherosclerosis after carotid endarterectomy occurs in 5-15% of the cases. The key event is the abnormal proliferation of arterial Smooth Muscle Cells (SMC). After endarterectomy SMC are directly exposed to the blood flowing under pressure. The aim of the present study was to ...

The aim was to study a relationship between the flow pattern in the ophthalmic artery (OA), the siphon and vessels within the circle of Willis. 27 patients, 22 males and 5 females, mean age 63 +/- 15 years (SD) with unilateral occlusion of the internal carotid artery (ICA) were examined ...

Patterns of collateral vascularization were investigated by SEM evaluation of microvascular corrosion casts following either ligation or embolization of the external carotid artery in the rabbit. Results indicated that rich collateral channels were established soon after ligation of this artery, and blood supply to the lesional area was never cut ...

The effects of right carotid artery ligation on the subsequent cerebral ischemia, induced by iron particle injection, in rabbits, were evaluated by recording somatosensory evoked potentials (SEPs) and cerebral blood flow (CBF) using laser Doppler flowmetry. Iron particle injection decreased CBF over 120 min and delayed SEP onset latency in ...

BACKGROUND AND PURPOSE: We sought to investigate whether the combination of blood flow measurements in the major cerebral arteries and measurements of cerebral metabolism can provide new insight into the hemodynamic effect of carotid lesions in patients with severe stenosis (> 70% reduction in diameter) of the internal carotid artery ...

Several acutely acting antimigraine drugs, including sumatriptan and other second generation 5-HT1D receptor agonists, have the ability to constrict porcine carotid arteriovenous anastomoses as well as the human isolated coronary artery. These two experimental models seem to serve as indicators, respectively, for the therapeutic and coronary side-effect potential of the ...

In a prospective study of the natural development of total cerebral blood flow volume (CBFV), the common, external and internal carotid and vertebral arteries were examined in 94 healthy children and adolescents between 3 and 18 years of age (sex and age evenly distributed) using a 7.0-MHz transducer of a ...

OBJECTIVE: Hypothermia has been demonstrated to protect the brain from ischemic or traumatic injury. Previous efforts to induce cerebral hypothermia have relied on techniques requiring total body cooling that have resulted in serious cardiovascular derangements. A technique to selectively cool the brain, without systemic hypothermia, may have applications for the ...

OBJECTIVE: To visualize the intra- and extracranial blood vessels during cross-clamping of the descending thoracic aorta. EXPERIMENTAL DESIGN: Experimental animal study. SETTING: Animal laboratory, University Hospital. MATERIALS: Seven pigs. INTERVENTIONS: Cross-clamping of the descending thoracic aorta for 30 minutes. METHOD: Selective carotid angiography was performed before, during and after cross-clamping. ...

The technical feasibility of selective intranidal endovascular occlusion of experimental arteriovenous malformations with detachable superfine platinum electrodes was assessed in a swine model. The delivery and release of electrodes were performed within normal carotid retia mirabilia, the faster-flowing nidus (bilateral retia) of a carotid-jugular fistula-type model of an arteriovenous malformation, ...

Chronically implanted ultrasonic Doppler flowmeters were used to obtain simultaneously recorded flow velocity signals from internal carotid and vertebral arteries, and the sagittal sinus, in rabbits. All three signals increased to 144 +/- 7-215 +/- 35% of baseline during hypercapnia (arterial Pco2 55 mmHg) in both anesthetized and conscious animals. ...

INTRODUCTION: This study measured total and regional cerebral blood flow (BF) in baboons during +Gz-induced loss of consciousness (G-LOC) and during recovery from G-LOC. METHODS: Flowprobes (Transonic Inc., T201, Ithaca, NY) were placed on the common carotid and internal carotid arteries of five male baboons for continuous measurement of total ...

OBJECTIVE: To evaluate the effect of the hypoestrogenism induced by GnRH agonist (GNRH-a) therapy on cerebral vessel blood flow. DESIGN: Open, controlled study. SETTING: Tertiary care units of the University of Milan, Italy. PATIENTS: Young women scheduled to undergo 6 months of therapy with a GnRH-a; a control group was ...

OBJECTIVES: To examine the effects of either regional (RA) or general (GA) anaesthesia upon parameters of cerebral metabolism (near infrared spectroscopy, continuous jugular venous oximetry) during carotid endarterectomy. DESIGN: Prospective, non-randomised, observational study. MATERIALS: Sixty-five consecutive patients (33 RA; 32 GA) undergoing carotid endarterectomy. METHODS: (i) Near infrared spectroscopy: measurement ...

Magnetic resonance angiography (MRA) hs inherent artifacts due to variation in velocity and direction of flowing blood in the carotid bulb and regions of stenosis. We examined the efficiency of dual 3-inch surface coils to delineate carotid artery flow better. Carotid MRA was performed on ten healthy volunteers and six ...

The middle cerebral artery flow velocities were measured to test the hypothesis that transcranial Doppler is a useful technique for intraoperative monitoring in 50 consecutive carotid endarterectomies which were performed under local anaesthesia. The patients' neurological status was continuously monitored. The peak middle cerebral artery velocities were measured before clamping, ...

1. It has previously been shown that the antimigraine drug, sumatriptan, a putative 5-HT1D receptor agonist, decreases porcine common carotid and arteriovenous anastomotic blood flows, but slightly increases the arteriolar (capillary) blood flow to the skin and ears. Interestingly, such responses, being mediated by 5-HT1-like receptors, are resistant to blockade ...

We examined the developmental changes in carotid arterial blood flow in a group of neonates, infants, and children using a Doppler flowmeter. The mean, maximum and minimum carotid arterial blood flow (CABF) were measured serially in 35 healthy newborns during the first 5 days of life (total 175 records), and ...

BACKGROUND AND PURPOSE: This study tested the hypothesis that functional abnormalities of carotid and ocular arteries may improve after short-term regression of atherosclerosis, before regression of structural abnormalities. METHODS: We examined effects of short-term dietary treatment of atherosclerosis on carotid and ocular vascular responses to serotonin and to platelet activation ...

BACKGROUND: Recent studies have indicated that near-infrared spectroscopy (NIRS) could continuously and noninvasively observe the changes in cerebral oxygenation state during hypoxia and ischemia, using their optical properties. Its validity and usefulness during cerebrovascular surgery, however, still remain to be clarified. METHODS: Using NIRS, we continuously monitored the changes in ...

In cats anesthetized with alpha-chloralose, autoregulation of blood flow (F) in the middle meningeal and common carotid arteries was assessed by bleeding and subsequently reinfusing the animals to achieve a 25% step reduction in mean arterial blood pressure (P), while maintaining the systolic blood pressure >80 mmHg. The integrity of ...

OBJECTIVE: To determine whether a continuous time estimation task during test occlusions of either internal carotid artery would increase the ability to detect the earliest signs of cerebral ischaemia in the anterior circulation. METHODS: Four patients were involved in real time measurement of their timing accuracy before, during, and after ...

OBJECTIVES: To identify correctable technical errors following carotid endarterectomy using intraoperative colour duplex sonography (ATL, UM9, HDI). Results were compared with intraoperative flow measurements using an operative flow meter and with middle cerebral artery velocity measured by trans-cranial Doppler (TCD). DESIGN: Prospective study. MATERIALS AND METHODS: 50 consecutive patients undergoing ...

Cerebral vasodilatory testing provides an important measure of both the hemodynamic significance of arterial occlusive disease and the adequacy of collateral pathways. This study measured the extracranial intravascular volume flow rate response to acetazolamide using phase-contrast magnetic resonance angiography. From 10 patients with unilateral carotid transient ischemic attacks (TIAs), a ...

BACKGROUND AND PURPOSE: Carotid percutaneous transluminal angioplasty ( PTA) may offer an alternative treatment to carotid endarterectomy. However, in contrast to carotid endarterectomy, which has been shown to normalize impaired cerebral hemodynamics, the effects of carotid PTA are unknown. Therefore, we prospectively studied the effect of carotid PTA on both ...

Utilizing the UIC Vascular Laboratory Registry, we retrospectively analysed the significance of side to side middle cerebral artery (MCA) flow velocity differences. Side to side differences > 15 percent measured by transcranial Doppler were considered asymmetric. Asymmetric subjects had 5 times greater chance of having significant cervical carotid narrowing on ...

OBJECTIVE: To determine the validity of the neck extension-rotation test as a clinical screening procedure to detect decreased vertebrobasilar blood flow that might be associated with dizziness. DESIGN: Secondary analysis of a clinical screening test. METHODS: Twelve subjects with dizziness reproduced by the extension-rotation test and 30 healthy control subjects ...

METHODS: Eight patients with severe unilateral carotid stenosis (> 70%) were evaluated using PET to assess parametric changes in cerebral blood flow, blood volume, metabolic rate for oxygen, metabolic rate for glucose, oxygen extraction fraction and glucose extraction fraction. We performed these examinations because clinical history and physical exam results ...

OBJECTIVE: The purpose of this study was to establish a continuous measure of cerebral blood flow in the ovine fetus with a transit time flow probe. METHODS: Seven chronically catheterized fetal sheep were studied near term with placement of a 3R Transonic flow probe on the external carotid artery, just ...

Sensitivity of carotid blood flow to increased gravitational force acting in the head-to-tail direction(+Gz) was studied in diverse species of snakes hypothesized to show adaptive variation of response. Tolerance to increased gravity was measured red as the maximum graded acceleration force at which carotid blood flow ceased and was shown ...

BACKGROUND AND PURPOSE: The aim of this study was to investigate flow velocity and flow direction in the posterior communicating artery (PcomA) by means of transcranial color-coded duplex sonography (TCCD) and to compare the results with angiographic findings. METHODS: Thirty patients with unilateral occlusion of the internal carotid artery (ICA) ...

In the present study, finite element calculations are performed of blood flow in the carotid artery bifurcation under physiological flow conditions. The numerical results are compared in detail with laser-Doppler velocity measurements carried out in a perspex model. It may be concluded that the numerical model as presented here is ...

In this prospective clinical study of the early radiation effects on blood supply to the mouth and face, 44 patients (31 men-13 women, mean age 63.4 yrs) with oral tumors underwent surgery and adjuvant postoperative radiotherapy with conventional fractionation (mean dose at the neck approximately equal to 50 Gy). Blood ...

OBJECTIVES: Neutrophils may play an important role in cerebral ischaemia. We investigated whether neutrophil activation can be detected in cerebral venous blood during the mild cerebral hypoxia and reperfusion that occurs during carotid cross clamping and declamping for endarterectomy. DESIGN, SETTING AND MATERIALS: The ipsilateral jugular bulb was cannulated at ...

The cerebral oxygenation state of five patients was continuously and non-invasively monitored using near-infrared spectroscopy (NIRS) during carotid artery balloon occlusion for comparison with somatosensory evoked potential (SEP) monitoring and regional cerebral blood flow (rCBF) measurements. In patients with marked reduction of rCBF and deteriorated SEP, NIRS demonstrated a continuous ...

Cardiovascular functions were studied in semi-arboreal rat snakes (Elaphe obsoleta) following long-term, intermittent exposure to +1.5 Gz (head-to-tail acceleration) on a centrifuge. Snakes were held in a nearly straight position within horizontal plastic tubes during periods of centrifugation. Centrifugal acceleration, therefore, subjected snakes to a linear force gradient with the ...

The influence of local resistance and cardiac performance on peripheral blood acceleration was investigated in 14 healthy male volunteers. Steady and pulsatile flow was studied in the brachial and in the common carotid arteries, ie, two territories that exhibit marked differences in resistive characteristics. Instantaneous blood velocity (V), mean blood ...

This study was done to assess the validity of nontriggered 2D phase contrast MR angiography for measuring blood flow in human arteries and veins. Volume in the popliteal and internal carotid arteries was measured by nontriggered and triggered 2DPC in 1.3 normal volunteer (mean age 27, range 18-46). Parameter selection ...

PURPOSE: We wanted to characterize the immediate effect of endarterectomy on flow of the arteries composing the extracranial carotid artery system. METHODS: Transit time ultrasound probes were used to measure flow through the carotid bifurcation in 48 patients undergoing endarterectomy. Maximum single-diameter stenosis affecting the internal carotid artery (ICA) was ...

BACKGROUND AND PURPOSE: The acetazolamide effect is thought to reach a maximum at 10 to 20 minutes after administration. However, we sometimes encountered patients who showed a transient deterioration of ischemic symptoms several minutes after acetazolamide administration. We therefore considered that a steal phenomenon may occur before the acetazolamide effect ...

We analyzed the carotid artery blood flow waveform (CABFW) of an infant of a non-insulin dependent diabetic mother with hypertrophic cardiomyopathy (IDM cardiomyopathy) through multivariate autoregressive analysis and compared the developmental change of his CABFW with that of normal newborns. The total power was lower than normal newborns on the ...

The sensory neuropeptide, calcitonin gene-related peptide (alpha-CGRP), has been implicated in the pathogenesis of migraine headache. The present study aimed to evaluate the effects of intracarotid infusions of human alpha-CGRP (10, 30 and 100 pmol/kg.min; n = 8), as compared to that of saline (4 times; n = 8) on ...

Moyamoya disease is a vascular abnormality seen in children and adults characterized by progressive narrowing of the internal carotid, middle, anterior, and posterior cerebral arteries and the development of leptomeningeal and proximal internal carotid artery collaterals, which appear diaphanous on angiogram. Although adults tend to present with subarachnoid hemorrhage and ...