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Evaluation of common carotid hemodynamic forces. Relations with wall thickening
1Dipartimento di Medicina Sperimentale e Clinica "G. Salvatore," Centro Aterosclerosi, University of Catanzaro, Rome, Italy.
Insights
Hemodynamic factors like shear stress and wall tension influence atherosclerotic lesion development. Shear stress, not wall tension, was independently linked to intima-media thickness in healthy men.
Area of Science:
- Cardiovascular Physiology
- Biomedical Engineering
Background:
- Atherosclerotic lesion localization is influenced by hemodynamic forces.
- Shear stress and circumferential wall tension are key hemodynamic factors.
Purpose of the Study:
- Investigate relationships between shear stress, circumferential wall tension, and intima-media thickness (IMT) of the common carotid artery.
- Determine independent associations of these factors with IMT in healthy men.
Main Methods:
- Calculated shear stress (blood viscosity × blood velocity/internal diameter).
- Calculated circumferential wall tension (blood pressure × internal radius).
- Measured blood velocity, internal diameter, and IMT using high-resolution echo-Doppler in 58 healthy men.
Main Results:
- Mean shear stress inversely related to age, blood pressure, and BMI.
- Mean circumferential wall tension directly associated with age and BMI.
- IMT inversely associated with shear stress (r=0.55) and directly with wall tension (r=0.43).
- Shear stress independently associated with IMT; wall tension was not.
Conclusions:
- Common carotid shear stress varies among healthy individuals and decreases with age, blood pressure, and BMI.
- Circumferential wall tension is associated with wall thickness, age, and BMI.
- Shear stress is independently associated with common carotid IMT, irrespective of other factors.
Abstract:
The localization of atherosclerotic lesions is influenced by hemodynamic factors, namely, shear stress and tensive forces. The present study investigated the relationships between shear stress and circumferential wall tension and between these hemodynamic factors and the intima-media thickness (IMT) of the common carotid artery in healthy men. Fifty-eight subjects were studied. Shear stress was calculated as blood viscosityxblood velocity/internal diameter. Circumferential wall tension was calculated as blood pressurexinternal radius. Blood velocity, internal diameter, and IMT were measured by high-resolution echo-Doppler. Mean shear stress was 12.6+/-3.3 dynes/cm(2) (mean+/-SD; range, 4.8 to 20.4) and was inversely related with age, blood pressure, and body mass index (BMI). Mean circumferential wall tension was 3.4+/-0.6x10(4) dynes/cm (range 2.4 to 5.6) and was directly associated with age and BMI. IMT was inversely associated with shear stress (r=0.55, P<0. 0001) and directly associated with circumferential wall tension (r=0. 43, P<0.0001). Shear stress and circumferential wall tension were inversely correlated (r=0.66, P<0.0001). In multiple regression analysis, shear stress and (marginally) cholesterol were independently associated with IMT, whereas circumferential wall tension, age, and BMI were not. These findings confirm that common carotid shear stress varies among healthy individuals and decreases as age, blood pressure, and BMI increase. Our findings also demonstrate that circumferential wall tension is directly associated with wall thickness, age, and BMI and that shear stress is associated with common carotid IMT independent of other hemodynamic, clinical, or biochemical factors.