Intravascular turbulence in a diseased carotid bifurcation: Numerical study

S. Lee, S. W. Lee, P. F. Fischer, H. S. Bassiouny, Francis Loth

Research output: Contribution to journalConference articlepeer-review

Abstract

Diseased vessels experience a significantly different biomechanical environment than healthy vessels due to the presence of transitional and turbulent flow, which may be responsible for cell damage or plaque disruption. With an objective of investigating turbulent characteristics in a diseased vessel, direct numerical simulations were conducted based on a patient-specific carotid bifurcation with a severe stenosis under pulsatile flow conditions. Computerized tomography images and color Doppler ultrasound measurements were acquired to obtain the anatomical geometry and in vivo flow waveform, respectively. The spectral element method, which is ideally suited for transitional and turbulent flow simulation, was employed in the numerical technique. Transition to turbulent flow with chaotic velocity fluctuations triggered by Kelvin-Helmholtz instabilities in the internal carotid artery was observed in the systolic phase. Turbulence intensities were significantly enhanced downstream of the stenosis during the deceleration phase of systole. The interaction of two strong shear layers generated from the bifurcation apex and distal end of stenosis as well as flow separation due to complex irregular morphology, created large WSS spatial gradients in the stenosis and high WSS magnitudes (250–450 dyne/cm2). Turbulent pressure fluctuations downstream of the stenosis and a large transient pressure drop occurring over the stenosis region will likely produce significant dynamic stresses–cyclic loading on plaques. Turbulent velocity and pressure fluctuations in the post-stenotic region were observed in audible frequency range of 100–300 Hz. This study demonstrates the hemodynamic environment in a diseased carotid bifurcation to be extremely complex during systolic phase and significantly different than that of a healthy carotid bifurcation.

Original languageEnglish (US)
Pages (from-to)3411-3414
Number of pages4
JournalIFMBE Proceedings
Volume14
Issue number1
StatePublished - Jan 1 2007
Externally publishedYes
Event10th World Congress on Medical Physics and Biomedical Engineering, WC 2006 - Seoul, Korea, Republic of
Duration: Aug 27 2006Sep 1 2006

Keywords

  • Carotid artery bifurcation
  • Hemodynamics
  • Spectral element method
  • Stenosis
  • Turbulence

ASJC Scopus subject areas

  • Bioengineering
  • Biomedical Engineering

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