Functional TCD: Regulation of Cerebral Hemodynamics - Cerebral Autoregulation, Vasomotor Reactivity, and Neurovascular Coupling

2014 ◽  
pp. 40-56 ◽  
Author(s):  
Marc E. Wolf
Keyword(s):  
Cerebral Autoregulation ◽  
Neurovascular Coupling ◽  
Cerebral Hemodynamics ◽  
Vasomotor Reactivity

scholarly journals Cerebral autoregulation and neurovascular coupling are progressively impaired during septic shock: an experimental study

2020 ◽  
Vol 8 (1) ◽  
Author(s):  
Lorenzo Ferlini ◽  
Fuhong Su ◽  
Jacques Creteur ◽  
Fabio Silvio Taccone ◽  
Nicolas Gaspard
Keyword(s):  
Experimental Study ◽  
Septic Shock ◽  
Cerebral Autoregulation ◽  
Neurovascular Coupling

Abstract WP437: Sleep Apnea and Cerebral Blood Flow: the Role of Autoregulation

Stroke ◽  
2017 ◽  
Vol 48 (suppl_1) ◽  
Author(s):  
Sara K Rostanski ◽  
Andrew J Westwood ◽  
Mehran Baboli ◽  
Randolph S Marshall
Keyword(s):  
Risk Factor ◽  
Sleep Apnea ◽  
Phase Shift ◽  
Cerebral Autoregulation ◽  
Apnea Hypopnea Index ◽  
Stroke Risk Factor ◽  
Vasomotor Reactivity ◽  
Obstructive Sleep ◽  
Increased Risk ◽  
Dynamic Cerebral Autoregulation

Objective: Obstructive sleep apnea (OSA) is a stroke risk factor and is increasingly recognized as a risk factor for cognitive impairment. Altered cerebral autoregulation may play a role in these relationships. We measured the association between OSA and two forms of cerebral autoregulation: (1) dynamic cerebral autoregulation (DCA), which plays a homeostatic role; and (2) vasomotor reactivity (VMR), which is a measure of cerebrovascular reserve. We hypothesized that both VMR and DCA would be impaired in subjects with OSA. Methods: We recruited subjects with untreated OSA. VMR and DCA were measured with continuous transcranial Doppler (TCD) of the middle cerebral arteries (MCA). DCA was measured with phase shift analysis where lower degrees of phase shift indicate greater impairment; values <24 degrees are abnormal. VMR was measured as % change in MCA velocity in response to 5% CO2 inhalation; values <2% change are abnormal. We assessed the relationship between apnea-hypopnea index (AHI) and autoregulation using bivariate correlations (Pearson coefficient). We also assessed the association between moderate to severe OSA (AHI≥15) and abnormal autoregulation (Fisher’s exact test). Results: Twelve subjects were enrolled; 11 had TCD data. Mean age was 53 (SD 11) and the majority had moderate to severe OSA (median AHI 27, IQR 16-37). Mean VMR (% change in MCA velocity) was 3.1 (SD 0.7); mean phase shift was 34 degrees (SD 15). There was a moderate association between AHI and phase shift (r=-0.40); the correlation with VMR was weaker (r=-0.25). The proportion of subjects with abnormal DCA was greater among those with moderate-severe OSA compared to those with mild OSA (66.7% vs. 0%, p=0.2). No enrolled subjects had abnormal VMR. Conclusion: Moderate to severe OSA is associated with abnormal dynamic cerebral autoregulation and normal vasomotor reactivity. The mechanism underlying this dissociation may involve OSA-mediated inflammation and endothelial dysfunction. Further study may clarify how this dissociation relates to increased risk of cerebral ischemia among patients with OSA.

scholarly journals Quantification of dynamic cerebral autoregulation and CO2 dynamic vasomotor reactivity impairment in essential hypertension

2020 ◽  
Vol 128 (2) ◽  
pp. 397-409
Author(s):  
Vasilis Z. Marmarelis ◽  
Dae C. Shin ◽  
Mareike Oesterreich ◽  
Martin Mueller
Keyword(s):  
Essential Hypertension ◽  
Cerebral Autoregulation ◽  
Input Output ◽  
Physiological Mechanisms ◽  
Control Subjects ◽  
Vasomotor Reactivity ◽  
Model Based ◽  
Arterial Blood ◽  
Transfer Function Analysis ◽  
Dynamic Cerebral Autoregulation

The study of dynamic cerebral autoregulation (DCA) in essential hypertension has received considerable attention because of its clinical importance. Several studies have examined the dynamic relationship between spontaneous beat-to-beat arterial blood pressure data and contemporaneous cerebral blood flow velocity measurements (obtained via transcranial Doppler at the middle cerebral arteries) in the form of a linear input-output model using transfer function analysis. This analysis is more reliable when the contemporaneous effects of changes in blood CO2 tension are also taken into account, because of the significant effects of CO2 dynamic vasomotor reactivity (DVR) upon cerebral flow. In this article, we extract such input-output predictive models from spontaneous time series hemodynamic data of 24 patients with essential hypertension and 20 normotensive control subjects under resting conditions, using the novel methodology of principal dynamic modes (PDMs) that achieves improved estimation accuracy over previous methods for relatively short and noisy data. The obtained data-based models are subsequently used to compute indexes and markers that quantify DCA and DVR in each subject or patient and therefore can be used to assess the effects of essential hypertension. These model-based DCA and DVR indexes were properly defined to capture the observed effects of DCA and VR and found to be significantly different ( P < 0.05) in the hypertensive patients. We also found significant differences between patients and control subjects in the relative contribution of three PDMs to the model output prediction, a finding that offers the prospect of identifying the physiological mechanisms affected by essential hypertension when the PDMs are interpreted in terms of specific physiological mechanisms. NEW & NOTEWORTHY This article presents novel model-based methodology for obtaining diagnostic indexes of dynamic cerebral autoregulation and dynamic vasomotor reactivity in hypertension.

scholarly journals Impaired cerebral autoregulation and neurovascular coupling in middle cerebral artery stroke: Influence of severity?

2018 ◽  
Vol 39 (11) ◽  
pp. 2277-2285 ◽  
Author(s):  
Angela SM Salinet ◽  
Nathália CC Silva ◽  
Juliana Caldas ◽  
Daniel S de Azevedo ◽  
Marcelo de-Lima-Oliveira ◽  
...  
Keyword(s):  
Middle Cerebral Artery ◽  
Functional Outcome ◽  
Cerebral Artery ◽  
Cerebral Autoregulation ◽  
Cerebral Blood Flow Velocity ◽  
Neurovascular Coupling ◽  
Stroke Severity ◽  
Healthy Controls ◽  
Stroke Patients ◽  
Severe Stroke

We aimed to assess cerebral autoregulation (CA) and neurovascular coupling (NVC) in stroke patients of differing severity comparing responses to healthy controls and explore the association between CA and NVC with functional outcome. Patients admitted with middle cerebral artery (MCA) stroke and healthy controls were recruited. Stroke severity was defined by the National Institutes of Health Stroke Scale (NIHSS) scores: ≤4 mild, 5–15 moderate and ≥16 severe. Transcranial Doppler ultrasound and Finometer recorded MCA cerebral blood flow velocity (CBFv) and blood pressure, respectively, over 5 min baseline and 1 min passive movement of the elbow to calculate the autoregulation index (ARI) and CBFv amplitude responses to movement. All participants were followed up for three months. A total of 87 participants enrolled in the study, including 15 mild, 27 moderate and 13 severe stroke patients, and 32 control subjects. ARI was lower in the affected hemisphere (AH) of moderate and severe stroke groups. Decreased NVC was seen bilaterally in all stroke groups. CA and NVC correlated with stroke severity and functional outcome. CBFv regulation is significantly impaired in acute stroke, and further compromised with increasing stroke severity. Preserved CA and NVC in the acute period were associated with improved three-month functional outcome.

scholarly journals Neurovascular coupling and cerebral autoregulation in atrial fibrillation

2019 ◽  
Vol 40 (8) ◽  
pp. 1647-1657 ◽  
Author(s):  
Rehan T Junejo ◽  
Igor D Braz ◽  
Samuel JE Lucas ◽  
Johannes J van Lieshout ◽  
Aaron A Phillips ◽  
...  
Keyword(s):  
Atrial Fibrillation ◽  
Cerebral Artery ◽  
Cerebral Autoregulation ◽  
Visual Stimulation ◽  
Function Analysis ◽  
Neurovascular Coupling ◽  
Healthy Controls ◽  
Eyes Closed ◽  
Increased Risk ◽  
Transfer Function Analysis

The risk of cognitive decline and stroke is increased by atrial fibrillation (AF). We sought to determine whether neurovascular coupling and cerebral autoregulation are blunted in people with AF in comparison with age-matched, patients with hypertension and healthy controls. Neurovascular coupling was assessed using five cycles of visual stimulation for 30 s followed by 30 s with both eyes-closed. Cerebral autoregulation was examined using a sit–stand test, and a repeated squat-to-stand (0.1 Hz) manoeuvre with transfer function analysis of mean arterial pressure (MAP; input) and middle cerebral artery mean blood flow velocity (MCA Vm; output) relationships at 0.1 Hz. Visual stimulation increased posterior cerebral artery conductance, but the magnitude of the response was blunted in patients with AF (18 [8] %; mean [SD]) and hypertension (17 [8] %), in comparison with healthy controls (26 [9] %) ( P < 0.05). In contrast, transmission of MAP to MCA Vm was greater in AF patients compared to hypertension and healthy controls, indicating diminished cerebral autoregulation. We have shown for the first time that AF patients have impaired neurovascular coupling responses to visual stimulation and diminished cerebral autoregulation. Such deficits in cerebrovascular regulation may contribute to the increased risk of cerebral dysfunction in people with AF.

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