Assessment of intracranial hemodynamics in carotid artery disease by transcranial Doppler ultrasound

Lindegaard, Karl-Fredrik; Bakke, Søren Jacob; Grolimund, Peter; Aaslid, Rune; Huber, Peter M.; Nornes, Helge

doi:10.3171/jns.1985.63.6.0890

Cited by 258 publications

(108 citation statements)

References 21 publications

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“…The PI indicates the vascular resistance; therefore, PI was calculated during the whole experiment using the following equation (Lindegaard et al, 1985): PI = (Peak systolic flow velocityÀEnd-diastolic flow velocity)/Mean flow velocity.…”

Section: Pulsatility Indexmentioning

confidence: 99%

Acetazolamide-Induced Vasodilation Does Not Inhibit the Visually Evoked Flow Response

Yonai

Boms

Molnár

et al. 2009

J Cereb Blood Flow Metab

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Different methods are used to assess the vasodilator ability of cerebral blood vessels; however, the exact mechanism of cerebral vasodilation, induced by different stimuli, is not entirely known. Our aim was to investigate whether the potent vasodilator agent, acetazolamide (AZ), inhibits the neurovascular coupling, which also requires vasodilation. Therefore, visually evoked flow parameters were examined by transcranial Doppler in ten healthy subjects before and after AZ administration. Pulsatility index and peak systolic flow velocity changes, evoked by visual stimulus, were recorded in the posterior cerebral arteries before and after intravenous administration of 15 mg/kg AZ. Repeated-measures ANOVA did not show significant group main effect between the visually evoked relative flow velocity time courses before and after AZ provocation (P = 0.43). Visual stimulation induced significant increase of relative flow velocity and decrease of pulsatility index not only before but also at the maximal effect of AZ. These results suggest that maximal cerebral vasodilation cannot be determined by the clinically accepted dose of AZ (15 mg/kg) and prove that neurovascular coupling remains preserved despite AZ-induced vasodilation. Our observation indicates independent regulation of vasodilation during neurovascular coupling, allowing the adaptation of cerebral blood flow according to neuronal activity even if other processes require significant vasodilation.

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Section: Pulsatility Indexmentioning

confidence: 99%

Acetazolamide-Induced Vasodilation Does Not Inhibit the Visually Evoked Flow Response

Yonai

Boms

Molnár

et al. 2009

J Cereb Blood Flow Metab

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“…3 This landmark was found at depths between 50 mm and 60 mm in all subjects. The four MCA segments closest to the ICA bifurcation (5, 10, 15, and 20 mm away) were always found bilaterall~ but identification of the more distal MCA segments was more inconsistent.…”

Section: Cerebral Artery Identificationmentioning

confidence: 99%

“…This reference point is a useful landmark in TCD investigation. 3 Data were annotated from a total of 2,385 different recordings, each comprising at least 10 consecutive cardiac cycles. The systolic, diastolic, and time-mean blood velocities were read manually from the frozen spectral display by using the display cursor.…”

Section: Blood Velocity Measurementsmentioning

confidence: 99%

“…M easurement of cerebral artery blood velocity with transcranial Doppler (TCD) ultrasound allows the evaluation of individual cerebral hemodynamic states.t- 3 Blood velocities clearly above the normal are seen in vessels in so•called vasospasm after subarachnoid hemorrhage (SAH), 2.4• 6 in athero• sclerotic stenoses, 7 and in arteries feeding cerebral arteriovenous malformations.…”

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confidence: 99%

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Side-to-side differences and day-to-day variations of transcranial Doppler parameters in normal subjects.

Sorteberg

Langmoen

Lindegaard

et al. 1990

Journal of Ultrasound in Medicine

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We investigated 35 normal adults to assess variations in cerebral artery blood velocities, hemispheric blood velocity ratios, and pulsatility indices, both with regard to changes between the sides and between days. We found no significant variations between sides or days. Changes from one day to the next exceeding 20% in blood velocity in the middle cerebral artery (V MCA ), the M easurement of cerebral artery blood velocity with transcranial Doppler (TCD) ultrasound allows the evaluation of individual cerebral hemodynamic states.t-3 Blood velocities clearly above the normal are seen in vessels in so•called vasospasm after subarachnoid hemorrhage (SAH), 2.4• 6 in athero• sclerotic stenoses, 7 and in arteries feeding cerebral arteriovenous malformations.1 Further information of clinical interest is obtained from calculating the ratios between the blood velocities in different arteries in the same hemisphere,'-' and from the pulsatility index (PI; systolic velocity minus diastolic velocity divided by the time·mean velocity). 1 Longitudinal investigations in patients with SAH have shown that the blood velocities in these patients have a time courseu-u that resembles the well·known course of cerebral vasospasm demonstrated angiographically.12 To understand the possibilities and limitations of the TCD method in clinical and anterior cerebral artery (V ACA ), the distal extracranial internal carotid artery (V 1 CA), and in the hemispheric V MCA/V 1CA, V ACA/V 1CA, or V ACA/V MCA ratios, may be considered significant at the 95% level. KEY woRos: cerebral arteries; blood velocity; reproducibility; transcranial Doppler ultrasound. (J Ultrasound Med 9:403, 1990) research applications, it is essential to know how these parameters differ between the sides in normal subjects and how they may vary from one examination to another.The aim of the present study was to assess the differences between the sides and the day-to-day variations of the blood velocity in the middle (MCA), anterior (ACA), and posterior (PCA) cerebral arteries and in the distal extracranial internal carotid artery ( ICA; V MCA, V ACA , V PCA , and V ICA ); of the ratios (hemispheric indices) V MCA/V ICA, V N:.A/V JCA, V ACA/V MCA, and V PCAJV MCA ; and of the pulsatility index. Such data may represent a useful frame of reference when evaluating patients suspected of having cerebrovascular disorders.

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“…All the parameters and input quantities in the model were given values taken from the research (animal and/or human clinical) literature [8][9][10][11], in order to reproduce cerebral hemodynamics and intracranial dynamics of a normal subject. Input quantities are arterial pressure, sinus venous pressure and arterial CO 2 partial pressure.…”

Section: Parameter Assignmentmentioning

confidence: 99%

A comprehensive cerebrovascular simulation model for teaching and research

Ursino¹,

Giannessi²,

Murray³

2007

Modelling in Medicine and Biology VII

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A comprehensive mathematical model of cerebral hemodynamics, with separate regulation of multiple brain regions, is presented. The main sectors included in the model are: the Circle of Willis, the hemodynamic circulation in the six districts perfused by the cerebral arteries, venous return with collapsible veins, cerebrospinal fluid circulation, and intracranial elasticity. Furthermore, each cerebral district is independently regulated following changes in cerebral perfusion pressure and CO 2 tension. In this work, the model is used to analyze cerebral hemodynamics during unilateral stenosis or occlusion of an internal carotid artery, as well as to assess the compensatory role of the Circle of Willis and of cerebrovascular regulatory mechanisms. Results show that, in normal subjects, the action of local blood flow regulation mechanisms and compensation by the Circle of Willis ensure adequate ipsilateral blood flow even in the presence of total unilateral internal carotid artery occlusion. However, a steal phenomenon is observed (i.e., a decrease of blood flow in the ipsilateral region) following hypercapnia. Sensitivity analysis on the calibre of the communicating arteries reveals that the anterior communicating artery plays a pivotal role in ensuring blood flow in the ipsilateral side during internal carotid artery stenosis. The model may have important clinical and educational applications, allowing the assessment of blood perfusion to different brain regions in various pathophysiological cases.

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Assessment of intracranial hemodynamics in carotid artery disease by transcranial Doppler ultrasound

Cited by 258 publications

References 21 publications

Acetazolamide-Induced Vasodilation Does Not Inhibit the Visually Evoked Flow Response

Acetazolamide-Induced Vasodilation Does Not Inhibit the Visually Evoked Flow Response

Side-to-side differences and day-to-day variations of transcranial Doppler parameters in normal subjects.

A comprehensive cerebrovascular simulation model for teaching and research

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