Transfer Function Analysis of Cerebral Autoregulation Dynamics in Autonomic Failure Patients

Blaber, Andrew P.; Bondar, Roberta L.; Stein, Flo; Dunphy, Paul T.; Moradshahi, Peyman; Kassam, M.; Freeman, Roy

doi:10.1161/01.str.28.9.1686

Cited by 166 publications

(206 citation statements)

References 33 publications

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“…The BP-BFV phase shifts were similar to those observed during the Valsalva maneuver obtained from the MMPF method [17]. Such positive phase shift has been also reported using Fourier transform methods during head-up tilt, and was interpreted as a faster recovery of BFV mediated by the compensatory cerebral autoregulatory mechanisms [8,12,14,50]. Our previous studies showed that the reduction of the MMPF derived BP-BFV phase shifts was associated with impaired cerebral autoregulation in stroke and hypertensive subjects and in patients with traumatic brain injuries [17,51], indicating that MMPF results reflect dynamics of cerebral autoregulation.…”

Section: A Assessment Of Nonlinear Interactions Between Nonstatisupporting

confidence: 79%

“…A transfer function is typically used to explore the relationship between blood pressure (BP) and blood flow velocity (BFV) by calculating gain and phase shift between the BP and BFV power spectra [2,8,[10][11][12][13][14][15][16]. In this approach, it is presumed that signals are stationary, and are composed of superimposed sinusoidal oscillations of constant amplitude and period at a pre-determined frequency range.…”

Section: Introductionmentioning

confidence: 99%

“…This hypothesis is motivated by the observation that blood pressure and blood flow velocity can be entrained by respiration or other external perturbation [18,19], and exhibit spontaneous oscillations over a wide frequency ranges [0.05-0. 4 Hz] even during resting conditions [14,15,[20][21][22]. Therefore, similarly to BP and BFV oscillations introduced by the Valsalva maneuver, there would be phase shifts between spontaneous BP and BFV oscillations during baseline condition and BP-BFV phase shifts would be reduced in subjects with impaired autoregulation.…”

Section: Introductionmentioning

confidence: 99%

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Altered phase interactions between spontaneous blood pressure and flow fluctuations in type 2 diabetes mellitus: Nonlinear assessment of cerebral autoregulation

Peng

Huang

et al. 2008

Physica A: Statistical Mechanics and its Applications

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Cerebral autoregulation (CA) is an important mechanism that involves dilation and constriction in arterioles to maintain relatively s cerebral blood flow in response to changes of systemic blood pressure. Traditional assessments of CA focus on the changes of cerebral blood flow velocity in response to large blood pressure fluctuations induced by interventions. This approach is not feasible for patients with impaired autoregulation or cardiovascular regulation. Here we propose a newly developed technique-the multimodal pressure-flow (MMPF) analysis, which assesses CA by quantifying nonlinear phase interactions between spontaneous oscillations in blood pressure and flow velocity during resting conditions. We show that CA in healthy subjects can be characterized by specific phase shifts between spontaneous blood pressure and flow velocity oscillations, and the phase shifts are significantly reduced in diabetic subjects. Smaller phase shifts between oscillations in the two variables indicate more passive dependence of blood flow velocity on blood pressure, thus suggesting impaired cerebral autoregulation. Moreover, the reduction of the phase shifts in diabetes is observed not only in previously-recognized effective region of CA (<0.1Hz), but also over the higher frequency range from ~0.1 to 0.4Hz. These findings indicate that Type 2 diabetes alters cerebral blood flow regulation over a wide frequency range and that this alteration can be reliably assessed from spontaneous oscillations in blood pressure and blood flow velocity during resting conditions. We also show that the MMPF method has better performance than traditional approaches based on Fourier transform, and is more sui for the quantification of nonlinear phase interactions between nonstationary biological signals such as blood pressure and blood flow.

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Section: A Assessment Of Nonlinear Interactions Between Nonstatisupporting

confidence: 79%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Altered phase interactions between spontaneous blood pressure and flow fluctuations in type 2 diabetes mellitus: Nonlinear assessment of cerebral autoregulation

Peng

Huang

et al. 2008

Physica A: Statistical Mechanics and its Applications

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“…According to Diehl et al, a decrease of the phase angle below 60-90°i ndicates a more passive behavior of the cerebral vessel bed and is an indicator of impaired cerebral autoregulation [20,22,24]. In both our groups, the phase shift remained stable during LBNP confirming the assumptions of intact cerebral autoregulation during LBNP.…”

Section: Discussionsupporting

confidence: 76%

“…We normalized the transfer function gain by dividing the LF transfer function gain by the mean values of the input signal BP and the output signal CBFV of cerebral autoregulation, i.e. by cerebrovascular conductance (CBFV/BP) of each patient [24].…”

Section: Lbnp Protocolmentioning

confidence: 99%

Cardiovascular and cerebrovascular responses to lower body negative pressure in type 2 diabetic patients

Marthol¹,

Zikeli²,

Brown³

et al. 2007

Journal of the Neurological Sciences

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In diabetic patients, vascular disease and autonomic dysfunction might compromise cerebral autoregulation and contribute to orthostatic intolerance. The aim of our study was to determine whether impaired cerebral autoregulation contributes to orthostatic intolerance during lower body negative pressure in diabetic patients.Thirteen patients with early-stage type 2 diabetes were studied. We continuously recorded RR-interval, mean blood pressure and mean middle cerebral artery blood flow velocity at rest and during lower body negative pressure applied at −20 and −40 mm Hg. Spectral powers of RR-interval, blood pressure and cerebral blood flow velocity were analyzed in the sympathetically mediated low (LF: 0.04-0.15 Hz) and the high (HF: 0.15-0.5 Hz) frequency ranges. Cerebral autoregulation was assessed from the transfer function gain and phase shift between LF oscillations of blood pressure and cerebral blood flow velocity. In the diabetic patients, lower body negative pressure decreased the RRinterval, i.e. increased heart rate, while blood pressure and cerebral blood flow velocity decreased. Transfer function gain and phase shift remained stable.Lower body negative pressure did not induce the normal increase in sympathetically mediated LF-powers of blood pressure and cerebral blood flow velocity in our patients indicating sympathetic dysfunction. The stable phase shift, however, suggests intact cerebral autoregulation. The dying back pathology in diabetic neuropathy may explain an earlier and greater impairment of peripheral vasomotor than cerebrovascular control, thus maintaining cerebral blood flow constant and protecting patients from symptoms of presyncope.

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Vascular health across young adulthood and midlife cerebral autoregulation, gait, and cognition

Mahinrad

Shownkeen

Sedaghat

et al. 2020

Alzheimer's & Dementia

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Introduction To test the association of vascular health (VH) across young adulthood with midlife dynamic cerebral autoregulation (dCA), gait, and cognition; and to test whether dCA is a modifying factor. Methods We studied 196 participants from the Coronary Artery Risk Development in Young Adults cohort who were followed over 30 years. VH was assessed at each visit according to American Heart Association recommendations. At year 30, dCA was measured using transcranial Doppler ultrasound and several gait and cognitive domains were assessed. Results Worse VH from baseline through year 7, but not at year 30, was associated with less efficient dCA (all P < .05). Worse VH at all visits was associated with slower gait speed, and at year 7 with worse executive and global cognition (all P < .05). The association of baseline VH and midlife gait, but not cognition, was moderated by dCA (interaction P < .05). Conclusions VH as early as young adulthood may influence midlife brain health, and dCA may modify this relationship.

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Transfer Function Analysis of Cerebral Autoregulation Dynamics in Autonomic Failure Patients

Abstract: These data indicate an altered, yet present, autoregulatory response with autonomic failure.

Cited by 166 publications

References 33 publications

Altered phase interactions between spontaneous blood pressure and flow fluctuations in type 2 diabetes mellitus: Nonlinear assessment of cerebral autoregulation

Altered phase interactions between spontaneous blood pressure and flow fluctuations in type 2 diabetes mellitus: Nonlinear assessment of cerebral autoregulation

Cardiovascular and cerebrovascular responses to lower body negative pressure in type 2 diabetic patients

Vascular health across young adulthood and midlife cerebral autoregulation, gait, and cognition

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