Autoregulation in the Posterior Circulation Is Altered by the Metabolic State of the Visual Cortex

Kazuma Nakagawa*, Jorge M. Serrador, Sarah L. Larose, Fatemeh Moslehi, Lewis A. Lipsitz, Farzaneh A. Sorond

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

31 Scopus citations

Abstract

BACKGROUND AND PURPOSE-: Previous studies suggest that dynamic autoregulation in the posterior cerebral artery (PCA) is less efficient compared to the middle cerebral artery (MCA). We examined the role of cerebral vasodilation caused by metabolic activation (ie, visual stimulus) on autoregulatory characteristics in the 2 vascular territories. METHODS-: Blood flow velocity in the PCA and MCA and mean arterial pressure were measured continuously in 45 healthy volunteers (62±3 years) while seated with eyes open. Additional 20 subjects (60±5 years) were examined with eyes closed and open. Autoregulation was assessed using transfer function gains in both the PCA and MCA territories in the low (0.03-0.07 Hz), high (0.07-0.15 Hz), and cardiac (1 Hz) frequency ranges. RESULTS-: With eyes open, gains were significantly higher in the PCA compared to the MCA in the low (PCA: 1.41±0.09 vs MCA: 1.18±0.07; P=0.003) and high (PCA: 2.06±0.12 vs MCA: 1.61±0.08; P=0.0001) frequencies. Opening eyes increased blood flow velocity and reduced cerebrovascular resistance index in the PCA but not in MCA. This vasodilation in the PCA was associated with increased gain in the low (autoregulatory) frequency, whereas MCA gain did not change (PCA: 0.89±0.14 vs 1.31±0.17, MCA: 1.24±0.16 vs 1.16±0.11; P=0.02). CONCLUSIONS-: Dilation of the PCA territory during visual cortex activation resulted in increased PCA transfer function gain without changing MCA gain. Thus, impaired autoregulation in the PCA reported in previous literature is likely the result of metabolic vasodilation and not an inherent difference in the autoregulatory characteristics of the posterior circulation.

Original languageEnglish (US)
Pages (from-to)2062-2067
Number of pages6
JournalStroke
Volume40
Issue number6
DOIs
StatePublished - Jun 1 2009

Keywords

  • Cerebral autoregulation
  • Crebral blood flow
  • Posterior cerebral artery

ASJC Scopus subject areas

  • Clinical Neurology
  • Cardiology and Cardiovascular Medicine
  • Advanced and Specialized Nursing

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