Related Articles Biaxial mechanical properties of intact and layer-dissected human carotid arteries at physiological and supra-physiological loadings.

Am J Physiol Heart Circ Physiol. 2009 Dec 24;

Authors: Sommer G, Regitnig P, Költringer L, Holzapfel GA

Specimens of intact wall tubes of human common carotid arteries (CCA), internal carotid arteries (ICA) (n = 11, age 77.6 yrs, SD 6.3) and related adventitia and media-intima tubes are mechanically examined. Cyclic, quasi-static extension-inflation tests at different axial stretches are performed on pre-conditioned tube specimens. Stress-free configurations show significant stress releases in the circumferential direction of the intact CCA and ICA walls and in the axial directions of the intact CCA walls and the CCA and ICA adventitias. All investigated tissues exhibit strong nonlinear, pseudo-elastic mechanical behavior with small hysteresis. The 'inversion'-feature where the pressure/axial stretch relationship becomes a vertical line is found only for intact walls. Axial 'inversion stretches' are 1.15 (SD 0.06) for CCA, 1.14 (SD 0.06) for ICA, and related external axial forces are 0.43N (SD 0.15) and 0.30N (SD 0.22), respectively. Significant negative correlations between age and axial 'inversion stretches' for CCA (r = -0.67, P = 0.03) and ICA (r = -0.29, P = 0.04) are identified. Adventitias are very compliant at low pressures but change into stiff tubes at high pressures. The burst pressure of the adventitia is beyond 250 kPa. A relatively low burst pressure of approximately 60 kPa is found in the media-intima tubes in which the pressure/circumferential stretch relationships are almost independent of the axial stretches. Stress analyses indicate a high degree of material anisotropy for all investigated tissues. High circumferential and axial stresses occur in the media-intima tubes at physiological conditions. The obtained data are intended to serve for improving constitutive laws, determination of constitutive parameters, and enhancing our knowledge of the mechanical functions of arteries and their associated layers in specific pathophysiological and clinical problems, like hypertension and angioplasty and stenting. Key words: biomechanics, arterial wall mechanics, human carotid artery, biaxial testing.

PMID: 20035029 [PubMed - as supplied by publisher]