sexta-feira, setembro 27, 2013

Aortic Stiffiness: Hora de entender.

Stiffness should be understood as the resistance to deformation
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Aqui texto completo e elucidativo.
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The aorta stiffens with aging, a process that is accelerated by arterial hypertension. Decreased arterial compliance is one of the earliest detectable manifestations of adverse structural and functional changes within the vessel wall.
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Large arteries also have, aside from their properties of providing a conduit for blood to reach peripheral tissues, a critical role in providing adequate vascular buffering to each ventricular contraction through arterial-ventricular coupling. As such, the histological structure of the aorta varies immensely according to its site and function as a reservoir and conductive system (Windkessel principle). For instance, the proximal aorta is rich in elastin that allows the support of each systolic impulse and accommodates the stroke volume. Thus, the thoracic aorta and its immediate branches show greater elasticity, whereas more distal vessels become progressively stiffer, given the predominance of collagen fibers (5,000 times the tensile modulus of elastin) (2).

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