The viscoelastic and inertial properties of the arterial wall are responsible for the arterial functional role in the cardiovascular system. Cryopreservation is widely used to preserve blood vessels for vascular reconstruction but it is controversially suspected to affect the dynamic behaviour of these allografts. The aim of this work was to assess the cryopreservation's effects on human arteries mechanical properties. Common carotid artery (CCA) segments harvested from donors were divided into two groups: Fresh (n = 18), tested for 24-48 h after harvesting, and Cryopreserved (n = 18) for an average time of 30 days in gas-nitrogen phase, and finally defrosted. Each segment was tested in a circulation mock, and its pressure and diameter were registered at similar pump frequency, pulse and mean pressure levels, including those of normotensive and hypertensive conditions. A compliance transfer function (diameter/pressure) derived from a mathematical adaptive modelling was designed for the on line assessment of the arterial wall dynamics and its frequency response. Assessment of arterial wall dynamics was made by measuring its viscous (eta), inertial (M) and elastic (E) properties, and creep and stress relaxation time constant (tauC and tauSR, respectively). The frequency response characterization allowed to evaluate the arterial wall filter or buffer function. Results showed that non-significant differences exist between wall dynamics and buffer function of fresh and cryopreserved segments of human CCA. In conclusion, our cryopreservation method maintains arterial wall functional properties, close to their fresh values.

The aim of this study was to characterize and compare human great saphenous veins (HGSVs), HGSV cryoallografts, expanded polytetrafluoroethylene (ePTFE) segments, and elastic and muscular arteries' biomechanics, so as to identify if the biomechanical coupling and the HGSV advantages with respect to ePTFE depend on the arterial type and/or on the biomechanical property considered. Pressure and diameter were measured in vitro, under arterial hemodynamic conditions, in elastic and muscular arteries, and in vascular substitutes: fresh and cryopreserved HGSV and ePTFE segments. The wall's dynamics (compliance, viscosity, and inertia), energy dissipation, and buffering were calculated. The coupling was quantified for each biomechanical parameter. Cryopreservation preserved HGSV biomechanics. The HGSV cryoallografts' dynamics, energetics, and buffering were lesser with respect to both arteries, but were higher than the ePTFE. The coupling differed, depending on the arterial type and property considered. The biomechanical coupling depended on the artery and property considered. HGSV cryoallograft advantages over ePTFE were arterial type and property independent.

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