Large artery biomechanical adaptation induced by flow-overload

The present study set out to examine alterations in the biomechanical characteristics of large-artery wall in response to moderate blood flow increase, as such information is scarce in the literature. For this purpose, a shunt was created between the right carotid artery and ipsilateral jugular vein in a porcine animal model, as a result of which pressure remained unchanged but flow doubled at the proximal arterial segment until animal sacrifice one month later. The shunted and contralateral arterial (proximal) segments were excised for morphological observation, i.e. delineation of the stress-free geometry, and triaxial mechanical testing, i.e. pressurization and longitudinal extension. Blood flow elevation was accompanied by significant lumen enlargement and wall thickening at in-vivo conditions, allowing restoration of shear and intramural-stresses to homeostatic values within one month. The diameter range and shape of the diameter-pressure curves of shunted arteries was also modified, indicating alterations in elastic properties. At mean working pressures, compliance increased and elastic modulus decreased in shunted than contralateral arteries. Our data imply that the arterial morphology under sustained flow-overload adapts within the one-month period of our study, in order to normalize intimal shear and intramural stresses, but this is not the case with the biomechanical characteristics.