Determination of wall shear rate in the human carotid artery by magnetic resonance techniques
R Stokholm1, S Oyre, S Ringgaard
1Department of Cardiothoracic and Vascular Surgery T, Aarhus University Hospital, Skejby Sygehus, Aarhus, Denmark.
Insights
This study measured blood flow forces on the carotid bifurcation in healthy volunteers. High wall shear rates were observed at the flow divider, while the lateral wall showed low rates and high oscillation.
Area of Science:
- Cardiovascular fluid dynamics
- Biomedical engineering
- Medical imaging
Background:
- The carotid bifurcation is a common site for atherosclerosis.
- Understanding blood flow patterns is crucial for diagnosing and treating cardiovascular diseases.
Purpose of the Study:
- To quantify wall shear rates around the human carotid bifurcation throughout the cardiac cycle.
- To provide in vivo data on blood forces acting on the carotid bifurcation wall.
Main Methods:
- Prospective, open study involving eight healthy volunteers.
- Magnetic resonance imaging with high resolution and individually adjusted velocity encoding was used.
- Wall shear rates were measured, and wall shear stresses were calculated assuming a constant viscosity.
Main Results:
- Unidirectional wall shear rate waveforms and high wall shear rate (775 s⁻¹ ± 167 s⁻¹) were found at the flow divider.
- Low wall shear rate (60 s⁻¹ ± 40 s⁻¹) and a high oscillation index (85 ± 65) with significant interindividual variation were observed at the lateral wall.
Conclusions:
- These are the first in vivo data detailing blood forces on the carotid bifurcation wall.
- The findings support hypotheses linking low and oscillating wall shear stress to atherosclerosis development.
Objectives:
to measure wall shear rates around the circumference of the human carotid bifurcation throughout the heart cycle.
Design:
prospective, open study. Materials eight healthy volunteers.
Methods:
wall shear rates were determined at the carotid bifurcation using magnetic resonance techniques with high resolution and individually adjusted velocity encoding for imaging and haemodynamic mapping. Wall shear stresses were calculated assuming a constant value of 4 centiPoise.
Results:
data suitable for postprocessing were obtained in all subjects. The main findings were: unidirectional wall shear rate waveforms and high wall shear rate (775 s(-1)+/-167 s(-1)) at the flow divider; low wall shear rate (60 s(-1+/-40 s(-1)) and a high oscillation index with huge interindividual variation (85+/-65) at the lateral wall.
Conclusion:
these are the first in vivo data describing, in detail, the forces of the blood acting on the wall of the carotid bifurcation. The results do not contradict the hypotheses associating low and oscillating wall shear stress with the development of atherosclerosis.)