Autonomic Blockade During Sinusoidal Baroreflex Activation Proves Sympathetic Modulation of Cerebral Blood Flow Velocity

Hilz, Max J.; Koehn, Julia; Tillmann, A.; Riss, Stephan; Marthol, H.; Köhrmann, Martin; Wasmeier, Gerald; Schwab, Stefan; Stemper, Brigitte

doi:10.1161/strokeaha.111.680256

Cited by 8 publications

(24 citation statements)

References 57 publications

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“…HG maneuver alone increased variability, whereas HDT + HG did not alter MAP variability in the LF range (Table 2). Human and animal studies have shown that arterial blood pressure variability in the LF range is related to the sympathetic activity (Pagani et al 1986;Hilz et al 2013). Our results indicate an increase in the sympathetic activity during HG alone compared to rest (increased MAP variability, Table 2).…”

Section: Discussionsupporting

confidence: 49%

“…; Hilz et al. ). Our results indicate an increase in the sympathetic activity during HG alone compared to rest (increased MAP variability, Table ).…”

Section: Discussionmentioning

confidence: 96%

“…This was likely due to the baroreflex response to Mayer waves in MAP and cardiac stroke volume (Hilz et al. ).…”

Section: Discussionmentioning

confidence: 99%

“…There is also evidence that sympathetic activity directly induces or modulates oscillations in CBF velocity at 0.1 Hz (Hilz et al. ). Our results are in line with these findings.…”

Section: Discussionmentioning

confidence: 99%

“…High HR variability was observed at 0.1 Hz, and these HR oscillations were synchronized and in inverse phase with ICABV oscillations. This was likely due to the baroreflex response to Mayer waves in MAP and cardiac stroke volume (Hilz et al 2013).…”

Section: The Buffering Effect Of Heart Rate Variabilitymentioning

confidence: 99%

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Dynamic cerebral autoregulation is preserved during isometric handgrip and head-down tilt in healthy volunteers

2018

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In healthy humans, cerebral blood flow (CBF) is autoregulated against changes in arterial blood pressure. Spontaneous fluctuations in mean arterial pressure (MAP) and CBF can be used to assess cerebral autoregulation. We hypothesized that dynamic cerebral autoregulation is affected by changes in autonomic activity, MAP, and cardiac output (CO) induced by handgrip (HG), head‐down tilt (HDT), and their combination. In thirteen healthy volunteers, we recorded blood velocity by ultrasound in the internal carotid artery (ICA), HR, MAP and CO‐estimates from continuous finger blood pressure, and end‐tidal CO 2. Instantaneous ICA beat volume (ICABV, mL) and ICA blood flow (ICABF, mL/min) were calculated. Wavelet synchronization index γ (0–1) was calculated for the pairs: MAP–ICABF, CO–ICABF and HR–ICABV in the low (0.05–0.15 Hz; LF) and high (0.15–0.4 Hz; HF) frequency bands. ICABF did not change between experimental states. MAP and CO were increased during HG (+16% and +15%, respectively, P < 0.001) and during HDT + HG (+12% and +23%, respectively, P < 0.001). In the LF interval, median γ for the MAP–ICABF pair (baseline: 0.23 [0.12–0.28]) and the CO–ICABF pair (baseline: 0.22 [0.15–0.28]) did not change with HG, HDT, or their combination. High γ was observed for the HR–ICABV pair at the respiratory frequency, the oscillations in these variables being in inverse phase. The unaltered ICABF and the low synchronization between MAP and ICABF in the LF interval suggest intact dynamic cerebral autoregulation during HG, HDT, and their combination.

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Section: Discussionsupporting

confidence: 49%

“…; Hilz et al. ). Our results indicate an increase in the sympathetic activity during HG alone compared to rest (increased MAP variability, Table ).…”

Section: Discussionmentioning

confidence: 96%

“…This was likely due to the baroreflex response to Mayer waves in MAP and cardiac stroke volume (Hilz et al. ).…”

Section: Discussionmentioning

confidence: 99%

“…There is also evidence that sympathetic activity directly induces or modulates oscillations in CBF velocity at 0.1 Hz (Hilz et al. ). Our results are in line with these findings.…”

Section: Discussionmentioning

confidence: 99%

Section: The Buffering Effect Of Heart Rate Variabilitymentioning

confidence: 99%

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