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There is little information regarding age-related reference intervals (RIs) of carotid-femoral pulse wave velocity (cfPWV) for large healthy populations in South America. The aims of this study were to determine cfPWV RIs and percentiles in a cohort of healthy children, adolescents, and adults and to generate year-to-year percentile curves and body-height percentile curves for children and adolescents. cfPWV was measured in 1722 healthy participants with no cardiovascular risk factors (9-87 years, 60% men). First, RIs were evaluated for males and females through correlation and covariate analysis. Then, mean and standard deviation age-related equations were obtained for cfPWV using parametric regression methods based on fractional polynomials and age-specific (year-to-year) percentile curves that were defined using the standard normal distribution. Age-specific first, 2.5th, 5th, 10th, 25th, 50th, 75th, 90th, 95th, 97.5th, and 99th percentile curves were calculated. Finally, height-related cfPWV percentile curves for children and adolescents (<21 years) were established. After adjusting for age and blood pressure differences with respect to females, males showed higher cfPWV levels (6.60 vs 6.45 m/s; P < .01). Thus, specific RIs for males and females were reported. The study provides the largest database to date concerning cfPWV in healthy people from Argentina. Specific RIs and percentiles of cfPWV are now available according to age and sex. Specific percentiles of cfPWV according to body height were reported for people younger than 21 years., (©2018 Wiley Periodicals, Inc.)

Introduction: The association between arterial parameters and blood pressure (BP) interindividual variations could depend on the arterial segment, BP component (systolic, SBP; diastolic, DBP; pulse pressure, PP) and/or on whether central (cBP) or peripheral (pBP) BP variations are considered., Aim: To assess and compare arterial parameters variations associated with interindividual variations in cBP and pBP., Methods: Healthy subjects (n = 923; 488 males, 2-84 years) were included. pBP and cBP waves were obtained (Mobil-O-Graph; SphygmoCor). Arterial diameter, intima-media thickness, local elastic modulus (carotid, CEM; brachial, BEM; femoral, FEM) and regional (carotid-radial and carotid-femoral pulse wave velocity; crPWV and cfPWV) arterial stiffness were determined. Associations between BP and arterial parameters interindividual variations were analyzed and compared (correlations; linear regressions; slopes comparisons) considering data transformed into z-scores., Results: Given a variation in z-cSBP or z-pSBP, z-CEM, z-FEM and z-cfPWV (stiffness indexes), were among the parameters with major BP-associated variations. z-crPWV and z-cfPWV, rather than local stiffness indexes were the parameters with major variations associated with z-DBP variations. z-cPP or z-pPP were associated with z-CEM and z-FEM variations, but not with brachial or regional stiffness variations. Most of the arterial parameters-BP slopes did not show significant differences when considering a variation in z-cSBP and z-pSBP. z-CEM and z-FEM were mainly associated with z-cPP and z-pPP variations, respectively., Conclusion: Disregard of age and sex, the variations in arterial parameters associated with BP interindividual variations showed differences depending on whether variations were central or peripheral; in SBP, DBP or PP and depending on the arterial segment considered.

Background: There is an urgent need of vascular substitutes (VS) to be used in lower limb revascularization procedures when autologous veins are not available and synthetic prosthesis are contraindicated. Since the mechanical differences with respect to native vessels are determinants of the VS failure, the substitutes should have mechanical properties similar to those of the recipient vessels. The use of cryopreserved arteries (cryografts) could overcome limitations of available VS. These work aims were to characterize (a) native vessels/implanted cryografts mechanical and geometrical coupling, (b) cryografts capability to ensure mismatch levels lesser than those expected for expanded polytetrafluoroethylene (ePTFE), (c) cryografts functional properties considering their histological and ultra-structural characteristics., Methods: Instantaneous pressure (mechano-transducers) and diameter (B-mode echography) were obtained in implanted femoro-popliteal, ileo-femoro-popliteal and axilo-humeral cryografts (n=8), in femoral arteries from recipients (n=8), recipient-like (n=15) and multiorgan donors-like (n=15) subjects, and in ePTFE segments (n=10). Calculus: (a) Mechanical parameters: elastic modulus, arterial compliance, distensibility and characteristic impedance; (b) Arterial remodeling: diameter, wall thickness, cross-sectional area and wall-to-lumen ratio; (c) Native vessels/VS coupling. Histological and structural analysis were done in explanted femoro-popliteal and axilo-humeral cryografts (n=7)., Results: Post-implant the cryografts remodeled. Their stiffness increased and the conduit function diminished. Remodeling resulted in an improvement in native vessels/cryograft coupling, which was always better than native vessels/ePTFE coupling., Conclusions: Post-implant cryograft remodeling improved native vessels/cryografts coupling. Cryografts would have mechanical and geometrical advantages over ePTFE. Anastomotic cryograft remodeling differed from that expected only due to haemodynamic factors. The structural properties of the remodeled cryografts contribute to explain their functional characteristics., (Copyright © 2011 Elsevier Inc. All rights reserved.)

Background: The aims were to characterize in muscular arteries (a) the passive and active effects of the adventitia on vessel biomechanical properties and conduit function (CF), and (b) potential differences between the adventitial role in elastic and muscular arteries., Methods and Results: Ovine femoral arteries were studied in vivo and in vitro (reduced smooth muscle-tone) in a circulation mock-up during hemodynamic conditions similar to those found in vivo. Pressure and diameter were assessed before and after removing the adventitia. The arterial compliance, distensibility, stiffness beta-index and CF were quantified. Results were compared with those obtained in brachiocephalic trunks. In vivo, after removing the adventitia there was a nonsignificant diameter reduction and an increase in stiffness (P<0.05). The CF decreased in the early recordings (P<0.02). In vitro, there were no biomechanical changes but vascular dilatation after the adventitia removal. Biomechanical changes associated with the adventitia removal were higher in muscular arteries, whereas diameter changes were major in elastic vessels., Conclusions: After removing the adventitia, (a) the arterial stiffness and CF were modified in vivo only, suggesting the changes could be ascribed to variations in smooth muscle tone, and (b) changes in elastic and muscular arteries were quantitatively different.

Atherosclerotic plaque complication is a major cause of vascular accidents. Although a variety of factors have been proposed as key factors in these process, the mechanism that contribute to this problem remain to be characterized. Previously we demonstrated that changes in arterial wall viscous and elastic properties and/or in the filtering function (FF) could be part of the arterial wall alterations basis. If these properties are altered in arteries with atherosclerotic plaques remains to be analyzed. Our aims were 1) to analyze the arterial wall visco-elasticity and FF of carotid and femoral segments with atherosclerotic plaques, 2) to compare them with the mechanical behavior of segments without plaques (from the same artery) and of healthy arteries studied non-invasively. To this end, in each arterial segment, pressure and diameter signals were obtained, in vitro (circulation mock) and in vivo (non-invasive recordings). In atherosclerotic arteries recordings were performed on plaques and near regions without plaques. In each segment, the elasticity, the viscosity, and the wall FF were quantified. Atherosclerotic vessels, and particularly plaque regions, showed a reduced viscosity and FF. At the light of our results, hypothetical links between plaque events and changes in visco-elasticity and FF were discussed.

The ideal arterial graft must share identical functional properties with the host artery. Surgical reconstruction of the common carotid artery (CA) is performed in several clinical situations, using expanded polytetrafluoroethylene prosthesis (ePTFE) or saphenous vein (SV) grafts. At date there is interest in obtaining an arterial graft that improves the results of that nowadays available. The use of a fresh or cryopreserved/defrosted artery appears as an interesting alternative. However, if the fresh and cryopreserved/defrosted arteries allow an adequate viscoelastic and functional matching with the host arteries needs to be established. The aims were to compare the viscoelastic and functional performance of: (1) conduits used in CA reconstruction (SV and ePTFE) with those of the fresh and cryopreserved/ defrosted CA and femoral arteries (FA), and (2) normotensive and hypertensive patients' arteries with those of the arterial substitutes in vitro analyzed. Pressure, diameter and wall thickness of the CA were recorded in 15 normotensive and 15 hypertensive patients (in vivo studies), and in SV, fresh and cryopreserved/defrosted CA and FA (obtained from 15 donors), and ePTFE segments (in vitro studies). From stress-strain relationship we calculated elastic and viscous modulus, and the characteristic impedance. The local buffer and conduit functions were quantified as the viscous/elastic quotient and the inverse of the characteristic impedance. Fresh and cryopreserved/defrosted CA and FA were more alike, both in viscoelastic and functional levels, respect to normotensive and hypertensive patients' arteries, than the ePTFE and SV grafts. CA and FA cryografts could be considered an important alternative for carotid reconstruction.

Introduction and Objectives: It is not yet known whether cryopreservation enables vessels to retain their viscoelastic properties or whether cryopreserved homografts are biomechanically more like native arteries than currently used vascular prostheses. The study objectives were: a) to determine whether our cryopreservation methodology enables arterial and venous homografts to retain their viscoelastic and functional properties; and b) to assess similarities between patients' femoral arteries, homografts, and other vascular prostheses in common use., Methods: The pressure and the diameter and parietal thickness of 15 muscular (femoral) arteries were measured in patients using tonometry and echography, both noninvasive techniques. In addition, the pressure in and diameter and parietal thickness of 15 fresh and 15 cryopreserved human muscular (femoral) artery segments, saphenous veins, and 15 expanded polytetrafluoroethylene (ePTFE) vascular prostheses were measured in vitro under hemodynamic conditions similar to those in patients. A Kelvin-Voigt model of the segment wall was used to derive elastic (Epd, mm Hg/mm) and viscous (Vpd, mm Hg x s/mm) pressure-diameter indices, the buffering function (Vpd/Epd), and the conduit function (1/Zc, where Zc is the characteristic impedance). The incremental Young modulus, the pressure-strain elastic modulus, and pulse wave velocity were also calculated., Results: No difference was observed between either the viscoelastic or functional properties of fresh and cryopreserved homografts. Arterial homografts were the most similar to the patient's arteries., Conclusions: Cryopreservation enabled venous and arterial homografts to retain their viscoelastic and functional properties. Of all the grafts investigated, arterial homografts were most similar, both biomechanically and functionally, to the patient's femoral arteries.

The aim was to evaluate our cryopreservation method effects on the mechanical properties and filtering function of human superficial femoral arteries (SFA). SFA segments from 10 multiorgan donors were divided into two groups: fresh, tested 24-48 h after harvesting, and cryopreserved/defrosted, tested after 1 month of cryopreservation. The cooling process was carried out in three steps: 2 degrees C/min until -40 degrees C; 5 degrees C/min until -90 degrees C and finally a rapid cooling by transferring the bag to vapour phase of liquid nitrogen (-142 degrees C). Thawing was made in two steps, a slow warming time by exposing the bag to 20 degrees C during 20 min, followed by a rapid warming by immersion in a 40 degrees C warm bath until defrost. In a circulation mock, arterial pressure [Pressure signal (P)] and diameter [Diameter (D)] were registered at similar stretch-frequency, P and flow levels. A compliance transfer function (D/P) was used for the on-line assessment of the arterial wall elastic (E), viscous (eta), and inertial (M) properties. To evaluate the arterial wall filter function, the arterial wall D/P frequency response was characterized, the cut-off frequency (fc) was quantified, and the viscous energy dissipation (Weta) was calculated. After cryopreservation, there were not significant changes in E, eta, M, Weta, and fc.

Background: Wall shear stress, arterial wall elasticity, and intimal hyperplasia are related. The aim of this study was to investigate the in vitro mechanical properties of ovine femoral arteries, jugular veins, and expanded polytetrafluoroethylene conduits, and to evaluate postoperative intimal hyperplasia., Methods: Arterial, venous, and ePTFE mechanical properties were studied in a circulating loop at isobaric systemic pressures. Histological studies of intimal hyperplasia in ePTFE-bypassed femoral arteries with and without Miller cuffs were performed at the 40th and 120th day., Results: The incremental elastic modulus of veins was significantly higher than that of femoral arteries (P < 0.05), but significantly lower than that of ePTFE graft conduits (P < 0.05). Intimal hyperplasia was significantly less in Miller-cuff-bypassed arteries both at the 40th and 120th day (P < 0.01)., Conclusions: The Miller cuff acts as a mechanical adapter enhancing wall shear stress and the elastic matching between ePTFE and the native artery, resulting in an early decrease of intimal hyperplasia.