Correspondence of low mean shear and high harmonic content in the porcine iliac arteries.
BACKGROUND
Temporal variations in shear stress have been suggested to affect endothelial cell biology. To better quantify the range of dynamic shear forces that occur in vivo, the frequency content of shear variations that occur naturally over a cardiac cycle in the iliac arteries was determined.


METHODS
Computational fluid dynamic calculations were performed in six iliac arteries from three juvenile swine. Fourier analysis of the time-varying shear stress computed at the arterial wall was performed to determine the prevalence of shear forces occurring at higher frequencies in these arteries.


RESULTS
While most of each artery experienced shear forces predominantly at the frequency of the heart rate, the frequency spectra at certain regions were dominated by shear forces at higher frequencies. Regions whose frequency spectra were dominated by higher harmonics generally experienced lower mean shear stress. The negative correlation between shear and dominant harmonic was significant (p=0.002).


CONCLUSIONS
Since lesion development typically occurs in regions experiencing low time-average shear stress, this result suggests that the frequency content of the shear exposure may also be a contributing factor in lesion development. A better understanding of the vascular response to shear components of different frequencies might help rationalize the notion of "disturbed flow" as a hemodynamic entity.
Himburg
Heather A
HA
Department of Biomedical Engineering, Duke University, Durham, NC, USA.
Friedman
Morton H
MH
D000818:Animals; D001683:Biological Clocks / Q000502:physiology*; D001783:Blood Flow Velocity / Q000502:physiology*; D001794:Blood Pressure / Q000502:physiology*; D004548:Elasticity; D006339:Heart Rate / Q000502:physiology; D007083:Iliac Artery / Q000502:physiology*; D066298:In Vitro Techniques; D008955:Models, Cardiovascular; D011673:Pulsatile Flow / Q000502:physiology*; D033081:Shear Strength; D013552:Swine