Carly Herrera

Publications (2)1.9 Total impact

• Article: The effect of longitudinal pre-stretch and radial constraint on the stress distribution in the vessel wall: a new hypothesis.

  Wei Zhang, Carly Herrera, Satya N Atluri, Ghassan S Kassab
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  ABSTRACT: It is well known that blood vessels shorten axially when excised. This is due to the perivascular tethering constraint by side branches and the existence of pre-stretch of blood vessels at the in situ state. Furthermore, vessels are radially constrained to various extents by the surrounding tissues at physiological loading. Our hypothesis is that the axial pre-stretch and radial constraint by the surrounding tissue homogenizes the stress and strain distributions in the vessel wall. A finite element analysis of porcine coronary artery and rabbit thoracic aorta based on measured material properties, geometry, residual strain and physiological loading is used to compute the intramural stresses and strains. We systematically examined the effect of pre-stretch and external radial constraint in both vessels. Our results show that both stretching in the axial direction and compression in the radial direction lead to a more homogeneous strain and stress state in the blood vessel wall. A "uniform biaxial strain" hypothesis is proposed for the blood vessel wall and the ramifications are discussed.
  Mechanics & chemistry of biosystems: MCB 02/2005; 2(1):41-52.
• Article: Effect of surrounding tissue on vessel fluid and solid mechanics.

  Wei Zhang, Carly Herrera, Satya N Atluri, Ghassan S Kassab
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  ABSTRACT: There is no doubt that atherosclerosis is one of the most important health problems in the Western Societies. It is well accepted that atherosclerosis is associated with abnormal stress and strain conditions. A compelling observation is that the epicardial arteries develop atherosclerosis while the intramural arteries do not. Atherosclerotic changes involving the epicardial portion of the coronary artery stop where the artery penetrates the myocardium. The objective of the present study is to understand the fluid and solid mechanical differences between the two types of vessels. A finite element analysis was employed to investigate the effect of external tissue contraction on the characteristics of pulsatile blood flow and the vessel wall stress distribution. The sequential coupling of fluid-solid interaction (FSI) revealed that the changes of flow velocity and wall shear stress, in response to cyclical external loading, appear less important than the circumferential stress and strain reduction in the vessel wall under the proposed boundary conditions. These results have important implications since high stresses and strains can induce growth, remodeling, and atherosclerosis; and hence we speculate that a reduction of stress and strain may be atheroprotective. The importance of FSI in deformable vessels with pulsatile flow is discussed and the fluid and solid mechanics differences between epicardial and intramural vessels are highlighted.
  Journal of Biomechanical Engineering 01/2005; 126(6):760-9. · 1.90 Impact Factor