Response of Middle Cerebral Artery Volume Flow to Orthostasis

Müller, Hans Robert; Casty, M.; Moll, Roland; Zehnder, R.

doi:10.1159/000108822

Cited by 32 publications

(12 citation statements)

References 8 publications

(12 reference statements)

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“…Head upright tilt has been claimed to induce dilatation of the middle cerebral artery,19 but such calibre changes have been shown to be negligible,20 and thus allow reliable interpretation of TCD data during head up tilt.…”

Section: Methodsmentioning

confidence: 99%

Autonomic control of the cerebral circulation during normal and impaired peripheral circulatory control

Cencetti

Lagi

Cipriani

et al. 1999

Heart

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Objective-To determine whether oscillations in the cerebrovascular circulation undergo autonomic modulation in the same way as cardiovascular oscillations. Design-Cardiovascular and cerebrovascular oscillations were monitored at rest and during sympathetic stimulation (head up tilt). The association with and transmission of the oscillations in the sympathetic (low frequency, LF) and respiratory (high frequency, HF) bands was assessed. Subjects-13 healthy volunteers, 10 subjects with vasovagal syncope, and 12 patients with complicated non-insulin dependent diabetes mellitus. Main outcome measures-Power spectrum analysis of cerebral blood flow velocity, arterial blood pressure, and heart rate. Coherence analysis was used to study the association between each pair of oscillations. Phase analysis showed the delay of the oscillations in the cardiovascular signals with respect to the cerebrovascular signals.Results-The power in the sympathetic (LF) components in all the oscillations increased during head up tilt (p < 0.01) in the controls and in the subjects with vasovagal syncope, but not in patients with diabetes. Significant coherence (> 0.5) in the LF band was present between cerebrovascular and cardiovascular oscillations in most of the controls and in subjects with vasovagal syncope, but not in the diabetic patients (< 50% of the patients). In the LF band, cerebrovascular oscillations preceded the cardiovascular oscillations (p < 0.05) at rest in all groups: the phase shifts were reduced (p < 0.05) during head up tilt for all cardiovascular signals in healthy and syncopal subjects, but only for heart rate in diabetic patients. Conclusions-The cerebrovascular resistance vessels are subject to autonomic modulation; low frequency oscillations in cerebral blood flow velocity precede the resulting fluctuations in other cardiovascular signals. Autonomic neuropathy and microvascular stiVness in diabetic patients reduces this modulation. (Heart 1999;82:365-372)

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Section: Methodsmentioning

confidence: 99%

Autonomic control of the cerebral circulation during normal and impaired peripheral circulatory control

Cencetti

Lagi

Cipriani

et al. 1999

Heart

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“…The common carotid artery diameter of adults decreases as a result of standing [20]. To our knowledge no physiological mechanism or experimental evidence exists for an increase of the diameter of the MCA in orthostasis.…”

Section: Discussionmentioning

confidence: 89%

Cerebral blood flow velocities during orthostasis and physical exercise

Bode

1991

Eur J Pediatr

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The peak flow velocities in the middle cerebral artery were continuously recorded by transcranial Doppler sonography in 29 children. Arterial blood pressure and heart rates were measured every minute. The values observed during orthostasis and physical exercise were compared to baseline values obtained in the supine position. During orthostasis the velocities were, on average, reduced to 87%-94%, the minimal values being 75%-78% of the baseline values. The heart rate increased whereas blood pressure showed only minor alterations. Upon standing up the systolic peak flow velocity remained unchanged while the mean- and enddiastolic peak flow velocities decreased to 66% and 39% respectively. On average, the velocities increased to 103%-108% during physical exercise. Systolic blood pressure increased to the same extent, the heart rate even more. Continuous recording of cerebral blood flow velocities may be more useful than intermittent measurements of blood pressure to differentiate children with and without symptoms of orthostasis.

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“…Currently, the transcranial Doppler method is extensively used to measure MCA velocities during BP changes (Aaslid et al 1991), postural changes (Grubb et al 1991;MuÈ ller et al 1991;Frey et al 1993;Savin et al 1995), dynamic exercise and muscle ischaemia (Jùrgensen et al 1992a) and was previously demonstrated as being useful in quantifying cerebral autoregulation (Aaslid et al 1989). The Doppler method allows for cerebral¯ow modi®-cations (Madsen et al 1993) and indicates resistance changes (Jùrgensen et al 1992b;Bailliart et al 1993) but does not permit blood¯ow calculation, since the MCA diameter is not measurable.…”

Section: Discussionmentioning

confidence: 99%

Intra- and extracranial artery blood velocity during a sudden blood pressure decrease in humans

Savin

Siègelovà²,

Fisher³

et al. 1997

European Journal of Applied Physiology

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The intra- and extracerebral Doppler artery blood velocity responses to a 10-mmHg abrupt blood pressure (BP) decrease in ten healthy men were studied. This decrease was obtained using two cuffs placed over both thighs. First, cuffs were inflated to pressures greater than the arterial BP for 5 min. Next, they were deflated to 60 mmHg in order to prevent venous return from the legs. We obtained a decrease in mean arterial BP of from 101 (10) to 90 (10) mmHg [mean (SD), P < 0.01] without modifications in the heart rate [HR, 88 (14) beats min-1]. Middle cerebral artery mean blood velocity (MCAmv) decreased immediately from 50 (10) to 42 (12) cm s-1 (P < 0.05). Simultaneously, temporal superficial artery mean blood velocity (TSAmv) decreased from 11 (3) to 7 (2) cm s-1 (P < 0.05) and common carotid artery blood flow (CCAbf) decreased from 305 (23) to 233 (33) ml min-1 (P < 0.05). After 5 s, MCAmv and CCAbf returned to baseline values, whereas TSAmv [8 (2) cm s-1], mean arterial BP [86 (10) mmHg] remained low and HR increased [92 (12) beats min-1]. TSAmv, BP and HR returned to baseline values in 1 min. These data confirm that cerebral blood flow (CBF) is very rapidly regulated but that blood flow in extracranial territories is not and that it follows the arterial BP changes.

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Response of Middle Cerebral Artery Volume Flow to Orthostasis

Cited by 32 publications

References 8 publications

Autonomic control of the cerebral circulation during normal and impaired peripheral circulatory control

Autonomic control of the cerebral circulation during normal and impaired peripheral circulatory control

Cerebral blood flow velocities during orthostasis and physical exercise

Intra- and extracranial artery blood velocity during a sudden blood pressure decrease in humans

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