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 Hemodynamics and Atherosclerosis

Physiology – Pathophysiology

  • Types of blood flow (laminar, turbulent) and their determinants (Reynolds number).
  • Hemodynamic forces (shear stress, tensile stress): definitions and equations.
  • Vessel wall properties affecting the development of atherosclerosis (thickness, elasticity, number of vasa vasorum).
  • Shear stress effects on the endothelium.
  • Causes and effects of turbulence.
  • The role of hypertension in atherosclerosis.
  • Hemodynamic changes associated with arterial stenoses.
  • Hemodynamics associated with anastomoses.

Clinical implications

  • Plaque localization in the carotid bifurcation (the effects of low shear stress).
  • Plaque localization in the coronary arteries (the effects of heart rate).
  • Plaque localization in the aorta (the effects of low flow velocity, the curvature of the abdominal aorta and the aortic bifurcation).

References

Frangos SG, Gahtan V, Sumpio B. Localization of atherosclerosis: role of hemodynamics. Arch Surg 1999;134:1142-1149.

This review provides fundamental knowledge on the predominant hemodynamic forces that have been characterized: shear stress and cyclic circumferential strain. The role of hemodynamics in the localization of atherosclerosis is discussed as well as the intracellular events that link hemodynamic stimuli and endothelial cell response.

Davies PF, Polacek DC , Shi C, Helmke BP. The convergence of haemodynamics, genomics, and endothelial structure in studies of the focal origin of atherosclerosis. Biorheology 2002;39:299-306.

This article outlines how modern molecular techniques are being utilized in studies of endothelia mechanotransduction associated with controlled shear stress in vitro and hemodynamics in vivo. The value of such techniques as components of an integrated understanding of vascular rheology is emphasized.

Feldman CL, Stone PH. Intravascular hemodynamic factors responsible for progression of coronary atherosclerosis and development of vulnerable plaque. Curr Opin Cardiol 2000;15:430-440.

This review outlines the mechanisms that link hemodynamic factors to plaque development and rupture and describes in some detail recently developed techniques that, for the first time, make it possible to determine these factors in vivo.

Gimbrone MA Jr, Topper JN, Nagel T, Anderson KR, Garcia-Cardena G. Endothelial dysfunction, hemodynamic forces, and atherogenesis. Ann N Y Acad Sci 2000;902:230-240.

Phenotypic modulation of endothelium to a dysfunctional state contributes to the pathogenesis of cardiovascular diseases such as atherosclerosis. This article reviews the role of the vascular endothelium in the atherosclerotic disease process, the impact of the various types of hemodynamic forces on vessel wall biology and the mechanisms of endothelial gene regulation by biomechanical forces.

Vorp DA, Trachtenberg JD, Webster MW. Arterial hemodynamics and wall mechanics. Semin Vasc Surg 1998;11:169-180.

This article summarizes the basic concepts of arterial hemodynamics and wall mechanics as they relate to the development of arterial pathology. A few practical mathematical relationships and examples are provided for both illustration and utilization. The use of computer models for the estimation of wall stresses in individual abdominal aortic aneurysms is also discussed.

Posted June 2010