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Differential response of peripheral arterial compliance-related indices to a vasoconstrictive stimulus

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Maria Guerrisi, Italo Vannucci and Nicola Toschi

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Peripheral arterial elastic properties are greatly affected by cardiovascular as well as other pathologies, and their assessment can provide useful diagnostic indicators. The photoplethysmographic technique can provide finger blood volume and pressure waveforms non-invasively, which can then be processed statically or beat-to-beat to characterize parameters of the vessel wall mechanics. We employ an occlusion–deflation protocol in 48 healthy volunteers to study peripheral artery compliance-related indices over positive and negative transmural pressure values as well as under the influence of a valid vasoconstrictor (cigarette smoking). We calculate beat-to-beat indices (compliance index CI, distensibility index DI, three viscoelastic model parameters (compliance C, viscosity R and inertia L), pressure–volume loop areas A and damping factor DF as well as symmetrical (Cmax) and asymmetrical (CAmax) static compliance estimates, and their distributions over transmural pressure. All distributions are bell-shaped and centred on negative transmural pressure values. Distribution heights were significantly lower in the smoking group (w.r.t. the non-smoking group) for C, CI, DI and significantly higher in R and DF. The estimated volume signal time lag was also significantly lower in the smoking group. Left and right distribution widths were significantly different in all parameters/groups but DI (both groups), CAmax, A (smoking group) and L (non-smoking group), and positions of maxima/minima were significantly altered in CAmax, R and DF. C, DF and CI are seen to be most sensitive under this protocol, while Cmax and CAmax are seen to be insensitive. These quantities provide complementary, time- and transmural pressure-dependent information about arterial wall mechanics, and the choice of index should depend on the physiological conditions at hand as well as relevant time resolution and transmural pressure range.


PACS

87.63.L- Visual imaging

87.19.Ff Muscles

87.19.U- Hemodynamics

47.63.Cb Blood flow in cardiovascular system

87.19.R- Mechanical and electrical properties of tissues and organs

87.19.X- Diseases

Subjects

Fluid dynamics

Biological physics

Medical physics

Dates

Issue 1 (January 2009)

Received 10 July 2008, accepted for publication 19 November 2008

Published 22 December 2008



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