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Lack of association between carotid artery volume blood flow and cardiac output

B M Eicke1, J von Schlichting, S Mohr-Ahaly

  • 1Department of Neurology Johannes Gutenberg-University of Mainz, Germany.

Journal of Ultrasound in Medicine : Official Journal of the American Institute of Ultrasound in Medicine
|January 5, 2002
PubMed

Insights

Cerebral blood flow appears independent of cardiac output. This study found no direct correlation between cardiac output measures and carotid artery blood flow in patients, suggesting distinct regulatory mechanisms.

Area of Science:

  • Cardiovascular Physiology
  • Cerebrovascular Physiology

Background:

  • The relationship between cardiac output and cerebral perfusion remains incompletely understood.
  • Investigating this link is crucial for understanding brain blood supply regulation.

Purpose of the Study:

  • To determine the correlation between cardiac output and cerebral blood flow.
  • To assess if cardiac output influences cerebral perfusion using echocardiography and carotid artery flow measurements.

Main Methods:

  • Transthoracic echocardiography was used to measure cardiac output indices (stroke volume, ejection fraction, heart minute volume) in 43 patients.
  • Cerebral blood flow was assessed via color M-mode duplex measurements of bilateral common carotid artery blood flow.
  • Data were analyzed for correlations between cardiac output parameters and carotid artery flow.

Main Results:

  • No significant correlation was found between cardiac output indices (ejection fraction, stroke volume, heart minute volume) and absolute carotid artery blood flow, adjusted for age.
  • A significant inverse correlation (r = -0.8, P < .0001) was observed between the relative carotid volume flow (as a percentage of heart minute volume) and heart minute volume.
  • The relative fraction of carotid volume flow was 15% +/- 6% of heart minute volume.

Conclusions:

  • The findings suggest that cerebral blood flow is largely independent of cardiac output in the studied patient cohort.
  • This implies that the brain may employ autoregulatory mechanisms to maintain perfusion irrespective of beat-to-beat cardiac output variations.
Abstract

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