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Introduction: Peripheral and aortic systolic blood pressure (pSBP and aoSBP) were measured using different methodological and calibration approaches to analyze the association and agreement between pSBP and/or aoSBP, and the association of pSBP and aoSBP with left ventricle (LV) and atrium (LA) structural-functional characteristics., Methods: In healthy subjects (n = 269, age: 9-85 years; n = 147, age < 24 years) LV and LA parameters were echocardiography-derived. pSBP and aoSBP were obtained by brachial sub-diastolic (Mobil-O-Graph ® ) and supra-systolic oscillometry (Arteriograph ® ) and aortic diameter waveform re-calibration (RCD; ultrasonography), using three calibration schemes: systo-diastolic (SD), calculated mean (CM), and oscillometric mean (OscM)., Results: Always pSBP and aoSBP were positively associated; aoSBP obtained with the Mobil-O-Graph ® and calibrated to CM or OscM were the ones that showed the lowest levels of association with the remaining forms of aoSBP and pSBP. Bland-Altman related mean errors varied noticeably (e.g. - 27, - 23, - 17, - 12 or 8 mmHg when aoSBP obtained with MOG (OscM) was compared with data from other methodological and calibration schemes). The aoSBP data obtained with Mobil-O-Graph ® (calibration: CM and OscM) showed the highest levels of association with cardiac structural characteristics. aoSBP values obtained calibrating to OscM were higher than those obtained calibrating to SD or CM., Conclusions: aoSBP obtained with Mobil-O-Graph ® and calibrated to CM or OscM showed (1) lower association with other forms of aoSBP and pSBP determination and (2) higher levels of association with LV and LA structural characteristics. Differences in aoSBP data between approaches were more sensitive to the calibration method than to the device used.

An association between nutritional characteristics in theearlylife stages and the state of the cardiovascular (CV) system in early childhood itself and/or at the beginning of adulthood has been postulated. It is still controversial whether changes in weight, height and/or body mass index (BMI) during childhood or adolescence are independently associated with hemodynamics and/or arterial properties in early childhood and adulthood., Aims: First, to evaluate and compare the strength of association between CVproperties (at 6 and 18 years (y)) and (a) anthropometric data at specific growth stages (e.g., birth, 6 y, 18 y) and (b) anthropometric changes during early (0-2 y), intermediate (0-6 y), late (6-18 y) and global (0-18 y) growth. Second, to determine whether the associations between CVproperties and growth-related body changes depend on size at birth and/or at the time of CVstudy. Third, to analyze the capacity of growth-related body size changes to explain hemodynamic and arterial properties in early childhood and adulthood before and after adjusting for exposure to CV risk factors. Anthropometric, hemodynamic (central, peripheral) and arterial parameters (structural, functional; elastic, transitional and muscular arteries) were assessed in two cohorts (children, n = 682; adolescents, n = 340). Data wereobtained and analyzed following identical protocols., Results: Body-size changes in infancy (0-2 y) and childhood (0-6 y) showed similar strength of association with CV properties at 6 y. Conversely, 0-6, 6-18 or 0-18 ychanges were not associated with CV parameters at 18 y. The association between CV properties at 6 yand body-size changes during growth showed: equal or greater strength than the observed for body-size at birth, and lower strength compared to that obtained for current z-BMI. Conversely, only z-BMI at 18 y showed associations with CV z-scores at 18 y. Body size at birth showed almost no association with CVproperties at 6 or 18 y., Conclusion: current z-BMI showed the greatest capacity to explain variations in CV properties at 6 and 18 y. Variations in some CV parameters were mainly explained by growth-related anthropometric changes and/or by their interaction with current z-BMI. Body size at birth showed almost no association with arterial properties at 6 or 18 y.

Background: Despite the clinical utility of echocardiography to measure left atrial (LA) structure and function, there are scarcities of data about the percentiles of LA diameter (LA D ), LA volume (LA VOL ), and LA volume indexed by body surface area (LA VOL / BSA ) from prospective population-based studies in healthy children and adolescents from the Southern Cone of Latin America., Methods: Echocardiographic studies were obtained in 1095 healthy subjects nonexposed to cardiovascular risk factors (5-24 years). Age- and sex-specific reference values of LA D , LA VOL , and LA VOL / BSA were generated using parametric regression based on fractional polynomials., Results: After covariate analysis (ie, adjusting by age, body surface area), specific sex-specific percentiles were evidenced as necessaries. Age- and sex-specific 1st, 2.5th, 5th, 10th, 25th, 50th, 75th, 90th, 95th, 97.5th, and 99th percentile and curves were reported. Our percentiles showed high concordance and complementarity with what was previously reported for the population of North American, European, and Asiatic Populations., Conclusions: In children and adolescents, the interpretation of the LA size requires sex-related percentiles. This study provides the largest Argentinean database concerning percentile curves of LA D , LA VOL , and LA VOL / BSA obtained in healthy children and adolescents. These data are valuable in that they provide values with which data of populations of children, adolescents, and young adults can be compared., (© 2019 Wiley Periodicals, Inc.)

Despite the clinical utility of echocardiography to measure cardiac target organ injury (TOI) there are scarcities of data about the reference intervals (RIs) and percentiles of left ventricular (LV) mass (LVM) and derived indexes (LVMI and LVMI 2.7 ), relative wall thickness (LVRWT) and ejection fraction (LVEF) from population-based studies in children and adolescents. The aim of this study was to generate reference intervals RIs of LVM and derived indexes (LVMI and LVMI 2.7 ), LVRWT, and LVEF obtained in healthy children, adolescents, and young adults from a South-American population. Echocardiographic studies were obtained in 1096 healthy subjects (5-24 years). Age and sex-specific RIs of LVM, LVMI, LVMI 2.7 , LVRWT, and LVEF were generated using parametric regression based on fractional polynomials. After covariate analysis (i.e., adjusting by age, body surface area) specific sex-specific RIs were evidenced as necessaries. Age and sex-specific 1st, 2.5th, 5th, 10th, 25th, 50th, 75th, 90th, 95th, 97.5th, and 99th percentile and curves were reported and compared with previously reported RIs. RIs showed high concordance and complementarity with what was previously reported for the population of North-American children (0-18 years old). In conclusion, in children and adolescents the interpretation of the LVM, LVMIs, LVRWT, and LVEF RIs requires sex-related RIs. This study provides the largest Argentinean database concerning RIs and percentile curves of LVM, LVMIs, LVRWT, and LVEF as markers of cardiac TOI obtained in healthy children and adolescents. These data are valuable in that they provide RIs values with which data of populations of children, adolescents can be compared.

Age-related reference intervals (RIs) of aortic pulse wave velocity (Ao-PWV) obtained from a large healthy population are lacking in South America. The aims of this study were to determine Ao-PWV RIs in a cohort of healthy children and adolescents from Argentina and to generate year-to-year percentile curves. Ao-PWV was measured in 1000 healthy subjects non-exposed to traditional cardiovascular risk factors (Age: 10-22 y. o., 56% males). First, we evaluated if RIs for males and females were necessaries (correlation and covariate analysis). Second, mean (M) and standard deviation (SD) age-related equations were obtained for cf-PWV, using parametric regression methods based on fractional polynomials. Third, age-specific (year to year) percentiles curves (for all, males and females children and adolescents) were generated using the standard normal distribution. They were, age-specific 1st, 2.5th, 5th, 10th, 25th, 50th, 75th, 90th, 95th, 97.5th and 99th percentile curves and values. After covariate analysis (i.e., adjusting by age, jugulum-symphysis distance, body weight and height), specific RIs for males and females of children and adolescents were evidenced as necessaries. The equations were For all subjects: Ao-PWV&#95;Mean = 4.98 + 12.86x10 -5 Age 3 . Ao-PWV&#95;SD = 0.47 + 21.00x10 -6 Age 3 . For girls: Ao-PWV&#95;Mean = 5.07 + 10.23x10 -5 Age 3 . Ao-PWV&#95;SD = 0.50 + 10.00x10 -6 Age 3 . For boys: Ao-PWV&#95;Mean = 4.87 + 15.81x10 -5 Age 3 . Ao-PWV&#95;SD = 0.46 + 22.34x10 -6 Age 3 . Our study provides the largest database to-date concerning Ao-PWV in healthy children and adolescents in Argentina. Age-related equations (M and SD values) for Ao-PWV are reported by the first time. Specific RIs and percentiles of Ao-PWV are now available according to age and sex for an Argentinian population.

Background: Echocardiographic reference intervals (RIs) for left ventricular outflow tract (LVOT) and velocity time integral (VTI) are scarce in pediatrics., Aims: (a) to generate RIs and percentiles for LVOT, VTI, and hemodynamic variables in healthy children and adolescents from Argentina; (b) to analyze the equivalence between stroke volume (SV), cardiac output (CO), and cardiac index (CI) obtained from two-dimensional echocardiography (2D) and LVOT-VTI analysis with pulsed wave Doppler (PWD); and (c) to analyze the association between subjects' characteristics and VTI and LVOT-VTI-derived parameters., Methods: Two-dimensional and PWD studies were done in 385 subjects (5-24 years). Mean and standard deviation age-related and body surface area (BSA)-related equations were obtained for VTI and LVOT-VTI-derived parameters (parametric regression methods based on fractional polynomials). BSA- and age-specific percentiles were determined., Results: Pulsed wave Doppler- and 2D-derived parameters were positively correlated. However, PWD values were always lower than those from 2D. Specific RIs for PWD and 2D data were necessary. Covariance analysis showed that sex-specific RIs were required for LVOT, but not for VTI, VTI-derived CO and CI. Age-related RIs were obtained for LVOT, LVOT-VTI, and VTI-derived CO and CI. BSA-related RIs for VTI-derived CO and CI were obtained., Conclusions: Stroke volume, CO, and CI data from 2D and PWD are not equivalent. An accurate analysis of LVOT-VTI-derived parameters requires considering age and BSA. In this study, age- and BSA-related RIs and percentiles for LVOT, VTI, and hemodynamic parameters in healthy children and adolescents were determined, discriminating data according to the methodological approach (2D or PWD)., (© 2018 Wiley Periodicals, Inc.)

Aim: The aim was to analyze and compare the associations between body mass index (BMI) and structural and functional cardiovascular variables measured in children and adolescents., Methods: 609 healthy subjects (mean age/range 12/4-18 years, 45% females) were studied. Subjects' BMI and the corresponding z-scores (z-BMI) were determined. Cardiovascular measurements: peripheral and aortic blood pressure (BP), aortic wave-derived parameters, common carotid, femoral and brachial artery diameters and stiffness, carotid intima-media thickness, carotid-radial and carotid-femoral pulse wave velocity (crPWV, cfPWV) and cfPWV/crPWV ratio. Cardiovascular data were standardized (z-scores) using equations (fractional polynomials) obtained from a sub-group (reference population, n = 241) non-exposed to cardiovascular risk factors (CVRFs). Simple and multiple regression models were obtained for the associations between cardiovascular z-scores and z-BMI and/or z-BMI, age, sex and CVRFs., Results: z-BMI was associated with standardized cardiovascular variables, regardless of age, sex and CVRFs. BP (peripheral rather than aortic) was the variable with the greatest variations associated with z-BMI. Systolic (SBP) and pulse pressure (PP; in that order) were the variables with the highest variations associated with z-BMI. Carotid, but not femoral or brachial stiffness showed BP-dependent variations associated with z-BMI. Arterial diameters were associated with z-BMI, without differences among arteries., Conclusion: In children and adolescents, z-BMI was gradually and positively associated with haemodynamic (peripheral and central BP) and vascular parameters (structural and functional) with independence of age, sex and other CVRFs (Dyslipidemia, Hypertension, Smoke, Diabetes). There were differences in the associations depending on the arteries studied and on whether central or peripheral haemodynamic parameters were analyzed.

Age-related reference intervals (RIs) of central (aortic) systolic blood pressure (cSBP) and augmentation index (cAIx) obtained from large healthy population are lacking in Argentina (South America). Aims. To analyze the existence of associations among cSBP and cAIx with demographic, anthropometric, and hemodynamic parameters and to generate percentile curves and RIs adjusted to each level of age and gender and/or body height. cSBP and cAIx were measured in 1038 healthy children, adolescents, and young adults. First, we evaluated if RIs for males and females were necessary using correlation and covariate analysis. Second, mean (M) and standard deviation (SD) age-related equations were obtained for cSBP and cAIx, using parametric regression methods based on fractional polynomials. Third, age specific percentiles curves were generated. Fourth, body height specific percentiles curves were generated using a similar procedure. The obtained equations (considering age as independent variable) for all subjects (cSBP 0.26 and (cAIx + 12.001) 0.5 ) were as follows: cSBP Mean = 3.0581 + 0.2189 log(Age) - 0.001044Age; cSBP SD = -0.03919 + 0.1535 log(Age) - 0.004564Age; cAIx mean = 9.5226 - 6.1599 log(Age) + 0.1450Age; cAIx SD = 1.3880 - 0.8468 log(Age) + 0.03212Age. This study, performed in Argentinean healthy children, adolescents, and young adults with ages of 5 to 22 years, provides the first RIs and percentile curves of cSBP and cAIx. Additionally, specific body height-related cAIx percentiles are reported for the analyzed population. The RIs and percentiles contribute to the knowledge of arterial dynamic evolution along the normal aging process and the interpretation of data obtained in clinical research and daily clinical practice.

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.)

Reference intervals (RIs) of carotid intima media thickness (CIMT) from large healthy population are still lacking in Latin America. The aim of this study was to determine CIMT RIs in a cohort of 1012 healthy subjects from Argentina. We evaluated if RIs for males and females and for left and right carotids were necessary. Second, mean and standard deviation (SD) age-related equations were obtained for left, right, and average (left + right)/2) CIMT using parametric regression methods based on fractional polynomials, in order to obtain age-specific percentiles curves. Age-specific percentile curves were obtained. Males showed higher A-CIMT (0.577 ± 0.003 mm versus 0.566 ± 0.004 mm, P = 0.039) in comparison with females. For males, the equations were as follows: A-CIMT mean = 0.42 + 8.14 × 10 -5 ⁎Age 2 ; A-CIMT SD = 5.9 × 10 -2 + 1.09 × 10 -5 ⁎Age 2 . For females, they were as follows: A-CIMT mean = 0.40 + 8.20 × 10 -5 ⁎Age 2 ; A-CIMT SD = 4.67 × 10 -2 + 1.63 × 10 -5 ⁎Age 2 . Our study provides the largest database concerning RIs of CIMT in healthy people in Argentina. Specific RIs and percentiles of CIMT for children, adolescents, and adults are now available according to age and gender, for right and left common carotid arteries.

Background: High blood pressure states (HBP) would differ in wave components and reflections indexes, which could associate clinical and prognostic implications. The study aims: 1) to characterize the association of aortic wave components and reflection parameters (backward [Pb], forward [Pf], Pb/Pf ratio and augmentation index [AIx]) with demographic, anthropometric, hemodynamic and arterial parameters in healthy children and adolescents; 2) to generate multivariate prediction models for the associations, to contribute to understand the main determinants of Pf, Pb, Pb/Pf and AIx; 3) to identify if differences in wave reflection indexes observed in HBP could be explained by differences in the analyzed parameters., Methods: Healthy children and adolescents (n=816, females: 386; Age: 3-20 years) were studied., Evaluations: central aortic pressure and wave components (Pb, Pf, Pb/Pf and AIx determination with SphygmoCor [SCOR] and Mobil-o-Graph [MOG]); anthropometric assessment; regional arterial stiffness (carotid-femoral, carotid-radial pulse wave velocity [PWV] and PWV ratio); carotid intima-media thickness; carotid and femoral distensbility; cardiac output; systemic vascular resistances (SVR). Simple and multiple regression models were constructed to determine aortic wave parameters; the main explanatory variables. Normotensive and HBP groups were compared. Differences in wave reflection indexes were analyzed before and after controlling for explanatory variables. Equivalences between SphygmoCor and Mobil-O-Graph data were assessed (correlation and Bland-Altman analyses)., Results and Conclusion: There were systematic and proportional differences between the data obtained with SphygmoCor and Mobil-O-Graph devices. Heart rate (HR), peripheral pulse pressure, height and weight were the variables that isolated (simple associations) or combined (multiple associations), showed the major capability to explain interindividual differences in Pf, Pb, Pb/Pf and AIx. Arterial stiffness also showed explanatory capacity, being the carotid the artery with the major contribution. HBP associated higher Pf, Pb, AIx and lower Pb/Pf ratio. Those findings were observed together with higher weight, arterial stiffness and HR. After adjusting for anthropometric characteristics, HR, cardiac output and SVR, the HBP group showed greater Pf and Pb. Then, Pf and Pb characteristics associated with HBP would not be explained by anthropometric or hemodynamic factors. Evaluating wave components and reflection parameters could contribute to improve the comprehension and management of HBP states., (Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.)

Background: Pulse wave velocity ratio (PWV-ratio), a measure of central-to-peripheral arterial stiffness gradient, is calculated as a quotient between carotid-femoral and carotid-radial PWV (cf-PWV/cr-PWV). This new index has been reported to be significantly associated with increased mortality in hemodialyzed patients. Since several reports showed differences in arterial stiffness regarding the pathway where the vascular access (VA) is, the purpose of this research was: a) to compare arterial stiffness values obtained in the left and right sides of the body in hemodialyzed and non-hemodialyzed patients, and b) to analyze PWV-ratio values obtained on the side of the body where the VA was placed and compare them to its contralateral intact side. Since it is difficult to adequately measure cr-PWV in patients with a VA in the forearm, we measured the carotid- brachial PWV (cb-PWV) and used it to calculate PWV-ratio (cf-PWV/cb-PWV)., Methods: A Pearson's correlation and Bland & Altman analysis were performed in hemodialyzed (n=135) and non-hemodialyzed (n=77) patients, to quantify the equivalence between arterial stiffness parameters (cf-PWV, cb-PWV, PWV-ratio) obtained on each side of the body with respect to its contralateral side., Results: We conclude that PWV-ratio values measured on the side where the VA is placed were significantly higher than those obtained in its contralateral side, in hemodialyzed patients included in this research. Moreover, cf-PWV, cb-PWV and PWV-ratio values obtained on one side of the body were always highly correlated with its contralateral side., Conclusion: According to this research, any research involving PWV-ratio should always consider the observed territory., (Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.)

Background: Arterial changes associated with children and adolescents high blood pressure (HBP) states would vary depending on the arterial type, arterial indexes considered and/or on blood pressure (BP) levels., Aims: To determine in children and adolescents: 1) if there is gradual structural-functional arterial impairment associated with gradual peripheral (brachial) systolic BP (pSBP) level or z-score increases, and 2) whether subjects with HBP levels and those with normal BP differ in the profiles of arterial changes associated with pSBP deviations., Methods: 1005 asymptomatic children and adolescents were included. Clinical, anthropometric and arterial non-invasive evaluations were performed. Heart rate, brachial BP, aortic BP and wavederived parameters (i.e. augmentation index), carotid and femoral diameters, blood velocities and elastic modulus, carotid intima-media thickness and aortic pulse wave velocity, were obtained. Two groups were assembled: Reference (without cardiovascular risk factors (CVRFs); n=379) and HBP (n=175). Additionally, subjects were ascribed to groups according to their pSBP z-scores (z-score ≤ 0, 0< z-score < 1 or z-score ≥ 1). Age and sex-related mean and standard deviation equations were obtained for each variable (Reference group). Using those equations, data (entire population) were converted into z-scores. Groups were compared (absolute and z-scored variables) before and after adjusting for cofactors (ANOVA/ANCOVA). Linear regression analyses were done considering: pSBP and z-pSBP (independent) and absolute levels and z-scores for hemodynamic and arterial indexes (dependent variables). Differences in hemodynamic and arterial levels and z-scores variations (dependent) associated with variations in pSBP and z-pSBP (independent variable) were assessed. The slopes of the models for Reference and HBP groups were compared., Conclusion: HBP states associate hemodynamic and arterial changes not explained by exposure to other CVRFs, anthropometric or demographic factors. The higher the pSBP deviations from ageand sex-expected mean value in the Reference group, the higher the hemodynamic and arterial indexes deviation. The pSBP-related variations in hemodynamic and arterial indexes would not differ depending on whether HBP states are present or not., (Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.)

Vascular research in end-stage renal diseases is an interesting field in which the characterization of arterial stiffness proved to be valuable to predict morbidity and mortality. Particularly, patients on renal replacement therapy have been reported to have significant increases in arterial stiffness and cardiovascular mortality. The clinical relevance of the measurement of arterial stiffness is linked to therapeutical and preventive interventions. The purpose of this work is to analyze the results of the scientific research in the field of arterial stiffness, in which hemodialyzed patients were involved, emphasizing on clinical and in-vitro research carried out by our group compared to contributions previously reported in the specialized literature. These investigations are necessary to improve diagnostic strategies and monitor the arterial response to therapeutical interventions in chronic kidney disease., (Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.)

Introduction: The existing evidence indicates that primary prevention of atherosclerotic disease should begin in childhood. Detection of children and adolescents at risk for atherosclerosis may allow early intervention to decrease the atherosclerotic process, thereby preventing or delaying cardiovascular disease. Vascular reactivity (VR) is altered even by early atherosclerosis. Obesity is a main cardiovascular risk factor (CVRF) observed in childhood. If childhood obesity associates impaired macro and/or micro VR is controversial., Aims: To characterize macro and micro VR analyzing the stimulus and vascular response temporal profiles in children and adolescents considering their body mass index (BMI); and to assess potential associations between subjects' characteristics and the hyperemic stimulus and/or VR., Methods: Healthy subjects (n = 99, age 5-17 years, female 46%) were included. Considering the BMI, normal, overweight and obese groups were defined. CVRF exposure was assessed. Brachial flow-mediated dilation and reactive hyperemia, associated with transient ischemia (forearm cuff-inflation) were evaluated. Diameter, flow velocities, resistive indexes and shear-stress were determined before, during and after cuff-release. Complimentary VR indexes were computed. Aortic stiffness and aortic and brachial blood pressure were determined., Results: Obese showed the lowest and slowest macrovascular response (p < 0.05). Micro VR was not associated with obesity. Higher aortic stiffness levels were associated with slower macrovascular responses (p < 0.05)., Conclusion: Childhood obesity associates not only reduced, but also slowed macrovascular reactivity. Microvascular response to transient ischemia is preserved in obese children. Macro and microvascular responses would be non-associated phenomena in childhood. During childhood, VR dynamics would depend on the arterial stiffness.

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.

Purpose: The comparative effect of the intimal and adventitial layers on arterial biomechanics control, in basal and altered conditions, remains to be elucidated. This study aimed (1) to characterize the arterial conduit (CF) and buffering (distensibility) function of the iliac arteries in in vivo animals, in which the intimal and adventitial layers were removed; (2) to determine the effects of intra-aortic ballon pumping (IABP) on simultaneously de-adventitialized (DA) and de-endothelialized (DE) iliac arteries before and after induced heart failure., Methods: Pressure and diameter signals were measured in the iliac arteries of sheep (n = 7) in which the adventitial and intima layer were removed. Intra-aortic balloon pump (IABP) assistance was used in a control state and after heart failure induction., Results: Both DE and DA determined significant changes in arterial diameter, distensibility and CF. Changes were higher after DA than after DE in terms of distensibility and CF (p<0.05). DA followed by DE (DA + DE) showed significant increases in arterial diameter and CF, accompanied by a decrease in distensibility (p<0.05) with respect to intact arteries. Heart failure induction caused significant hemodynamic changes without modifying the already impaired local biomechanical parameters. Nonsignificant improvements in the biomechanical parameters of DA + DE iliac arteries were observed during IABP before and after heart failure induction., Conclusions: Biomechanical changes caused by DA of iliac arteries were more important than those observed after DE. The DA + DE arteries showed significant differences with respect to intact arteries and with DA or DE arteries. IABP-related effects on arterial mechanics were absent in DA + DE arteries.

Introduction: The etiology of the end-stage renal disease (ESRD) and the hydration status may be involved in the arterial stiffening process observed in hemodialyzed patients. The ratio between carotid-femoral and carotid-radial pulse wave velocity (PWV ratio) was recently proposed to characterize the patient-specific stiffening process., Aims: to analyze: (1) the PWV-ratio in healthy and hemodialyzed subjects, analyzing potential changes associated to etiologies of the ESRD, (2) the PWV-ratio and hydration status using multiple-frequency bioimpedance and, (3) the effects of hemodialysis on PWV-ratio in a 5-year follow-up., Methods: PWV-ratio was evaluated in 151 patients differentiated by the pathology determining their ESRD. Total body fluid (TBF), intra and extra cellular fluid (ICF, ECF) were measured in 65 of these patients using bioelectrical-impedance. The association between arterial, hemodynamic or fluid parameters was analyzed. PWV-ratio was evaluated in a group of patients (n = 25) 5 years later (follow-up study)., Results: PWV-ratio increased in the ESRD cohort with respect to the control group (1.03 ± 0.23 vs. 1.31 ± 0.37; p < 0.001). PWV-ratio in the diabetic nephropathy group was higher than in all other etiological groups (1.61 ± 0.33; p < 0.05). PWV-ratio was associated with TBF (r = -0.238; p < 0.05), ICF (r = -0.323; p < 0.01), ECF/ICF (r = 0.400; p < 0.001) and ECF/TBF (r = 0.403; p < 0.001). PWV-ratio calculated in ESRD patients in 2007 increased 5 years later (1.14 ± 0.32 vs. 1.43 ± 0.44; p < 0.005)., Conclusions: PWV-ratio increased the most in patients with diabetic nephropathy. PWV ratio was significantly associated with age and body hydration status, but not with the blood pressure. PWV-ratio could be considered a blood pressure-independent parameter, associated with the age and hydration status of the patient.

Introduction: In adults, central blood pressure (cBP) is reported to associate target organ damages (TODs) rather than peripheral blood pressure (pBP). However, data regarding the association of pre-clinical TODs with cBP and pBP in pediatric populations are scarce., Aim: To evaluate in children and adolescents the importance of cBP and pBP levels, in terms of their association with hemodynamic and vascular changes., Methods: 315 subjects [age (mean/range) 12/8-18 years] were included., Measurements: pBP (oscillometry, Omron-HEM433INT and Mobil-O-Graph), cBP levels and waveforms (oscillometry, Mobil-O-Graph; applanation tonometry, SphygmoCor), aortic wave reflection-related parameters, carotid intima-media thickness (CIMT) and carotid (elastic modulus, stiffness-index) and aortic stiffness (carotid-femoral pulse wave velocity, PWV). Four groups were defined considering pBP and cBP percentiles (th): cBP ≥90th, cBP <90th, pBP ≥90th, pBP <90th. In each group, haemodynamic and vascular parameters were compared for subgroups defined considering the level of the remaining blood pressure (cBP or pBP). Subgroups were matched for anthropometric and cardiovascular risk factors (propensity matching-score)., Results: Subjects with high cBP showed a worse cardiovascular risk profile in addition to worse peripheral hemodynamic conditions. The CIMT, carotid and aortic stiffness levels were also higher in those subjects. CIMT and carotid stiffness remained statistically higher when subjects were matched for pBP and other cardiovascular risk factors. There were no differences in arterial properties when subjects were analyzed (compared) considering similar pBP levels, during normal and high cBP conditions., Conclusion: Compared with pBP, the cBP levels show a greater association with vascular alterations (high CIMT and arterial stiffness), in children and adolescents.

Successful clinical use of patient-specific models for cardiovascular dynamics depends on the reliability of the model output in the presence of input uncertainties. For 1D fluid dynamics models of arterial networks, input uncertainties associated with the model output are related to the specification of vessel and network geometry, parameters within the fluid and wall equations, and parameters used to specify inlet and outlet boundary conditions. This study investigates how uncertainty in the flow profile applied at the inlet boundary of a 1D model affects area and pressure predictions at the center of a single vessel. More specifically, this study develops an iterative scheme based on the ensemble Kalman filter (EnKF) to estimate the temporal inflow profile from a prior distribution of curves. The EnKF-based inflow estimator provides a measure of uncertainty in the size and shape of the estimated inflow, which is propagated through the model to determine the corresponding uncertainty in model predictions of area and pressure. Model predictions are compared to ex vivo area and blood pressure measurements in the ascending aorta, the carotid artery, and the femoral artery of a healthy male Merino sheep. Results discuss dynamics obtained using a linear and a nonlinear viscoelastic wall model., (Copyright © 2017 by ASME.)

Aims: To analyze the early vascular aging (EVA) in end-stage renal disease (ESRD) patients, attempting to determine a potential association between EVA and the etiology of ESRD, and to investigate the association of hemodialysis and EVA in ESRD patients during a 5-year follow-up period., Methods: Carotid-femoral pulse wave velocity (cfPWV) was obtained in 151 chronically hemodialyzed patients (CHP) and 283 control subjects, and in 25 CHP, who were followed-up after a 5-year lapse., Results: cfPWV increased in ESRD patients compared to control subjects. The cfPWV-age relationship was found to have a steeper increase in ESRD patients. The highest cfPWV and EVA values were observed in patients with diabetic nephropathy. Regression analysis demonstrated a significant reduction of the EVA in HD patients on a 5-year follow-up., Conclusion: Patients in ESRD showed higher levels of EVA. cfPWV and EVA differed in ESRD patients depending on their renal failure etiology. CHP showed an EVA reduction after a 5-year follow-up period., (© 2016 S. Karger AG, Basel.)

The aims were to determine whether children's high peripheral blood pressure states (HBP) are associated with increased central aortic blood pressure (BP) and to characterize hemodynamic and vascular changes associated with HBP in terms of changes in cardiac output (stroke volume, SV), arterial stiffness (aortic pulse wave velocity, PWV), peripheral vascular resistances (PVR) and net and relative contributions of reflected waves to the aortic pulse amplitude. We included 154 subjects (mean age 11; range 4-16 years) assigned to one of two groups: normal peripheral BP (NBP, n = 101), defined as systolic and diastolic BP < 90th percentile, or high BP (HBP, n = 53), defined as average systolic and/or diastolic BP levels ≥90th percentile (curves for sex, age and body height). The HBP group included children with hypertensive and pre-hypertensive BP levels. After a first analysis, groups were compared excluding obese and dyslipidemic children. Peripheral and central aortic BP, PWV and pulse wave-derived parameters (augmentation index, forward and backward wave components' amplitude) were measured using gold-standard techniques, applanation tonometry (SphygmoCor) and oscillometry (Mobil-O-Graph). Independent of the presence of dyslipidemia and/or obesity, aortic systolic and pulse BP were higher in HBP than in NBP children. The increase in central BP could not be explained by an increase in the relative contribution of reflections to the aortic pressure wave, higher PVR or by an augmented peripheral reflection coefficient. Instead, the rise in central BP would be explained by an increase in the amplitude of both incident and reflected wave components.

Aim. To analyze if childhood obesity associates with changes in elastic, transitional, and/or muscular arteries' stiffness. Methods. 221 subjects (4-15 years, 92 females) were assigned to normal weight (NW, n = 137) or obesity (OB, n = 84) groups, considering their body mass index z-score. Age groups were defined: 4-8; 8-12; 12-15 years old. Carotid, femoral, and brachial artery local stiffness was determined through systodiastolic pressure-diameter and stress-strain relationships. To this end, arterial diameter and peripheral and aortic blood pressure (BP) levels and waveforms were recorded. Carotid-femoral, femoropedal, and carotid-radial pulse wave velocities were determined to evaluate aortic, lower-limb, and upper-limb regional arterial stiffness, respectively. Correlation analysis between stiffness parameters and BP was done. Results. Compared to NW, OB subjects showed higher peripheral and central BP and carotid and femoral stiffness, reaching statistical significance in subjects aged 12 and older. Arterial stiffness differences disappeared when levels were normalized for BP. There were no differences in intrinsic arterial wall stiffness (elastic modulus), BP stiffness relationships, and regional stiffness parameters. Conclusion. OB associates with BP-dependent and age-related increase in carotid and femoral (but not brachial) stiffness. Stiffness changes would not be explained by intrinsic arterial wall alterations but could be associated with the higher BP levels observed in obese children.

The aims were to determine if childhood obesity is associated with increased central aortic blood pressure (BP) and to characterize haemodynamic and vascular changes associated with BP changes in obese children and adolescents by means of analyzing changes in cardiac output (stroke volume, SV), arterial stiffness (aortic pulse wave velocity, PWV), peripheral vascular resistances (PVR), and net and relative contributions of reflected waves to the aortic pulse wave amplitude. We included 117 subjects (mean/range age: 10 (5-15) years, 49 females), who were obese (OB) or had normal weight (NW). Peripheral and central aortic BP, PWV, and pulse wave-derived parameters (augmentation index, amplitude of forward and backward components) were measured with tonometry (SphygmoCor) and oscillometry (Mobil-O-Graph). With independence of the presence of dyslipidemia, hypertension, or sedentarism, the aortic systolic and pulse BP were higher in OB than in NW subjects. The increase in central BP could not be explained by the elevation in the relative contribution of reflections to the aortic pressure wave and higher PVR or by an augmented peripheral reflection coefficient. Instead, the rise in central BP could be explained by an increase in the amplitude of both incident and reflect wave components associated to augmented SV and/or PWV.

Aortic stiffness is a prognostic parameter associated with patient mortality. Vascular access creation has been shown to have effects on arterial stiffness both in the aorta and in the upper limb arteries in chronically hemodialyzed patients (CHPs). However, no longitudinal studies have been conducted in order to characterize the evolution of arterial stiffness in CHPs. The aims of this work were (a) to measure baseline pulse wave velocity (PWV) in the carotid-femoral and in right and left carotid-brachial pathways in a cohort of CHP and (b) to conduct a 5-year prospective study on the same cohort to determine possible time-related differences. Pulse wave velocity was measured both in the carotid-femoral and in the carotid-brachial pathways, and clinical and biochemical parameters were collected in 25 CHPs, which were followed up after a 5-year lapse. Right and left carotid-brachial pathway PWV values showed significant decreases after the 5-year follow-up, independently of the presence of the vascular access (P < 0.001). Additionally, baseline carotid-brachial PWV was significantly higher (P < 0.001) than values measured 5 years later for upper limbs with vascular access (11.97 ± 2.97 m/sec vs. 6.76 ± 1.48 m/sec, respectively) and without vascular access (12.25 ± 2.38 m/sec vs. 7.18 ± 1.88 m/sec, respectively). Similarly, PWV values in the carotid-femoral pathway decreased significantly (P < 0.001) over the same period (13.27 ± 2.96 m/sec vs. 9.75 ± 2.99 m/sec, respectively). The 5-year follow-up of PWV showed significant decreases in both carotid-brachial and carotid-femoral pathways. The general changes in arterial stiffness could be related to the vascular access creation, hemodialysis therapy, and to the improvement of arterial pressure management., (© 2015 International Society for Hemodialysis.)

Background. Adequate fluid management could be essential to minimize high arterial stiffness observed in chronically hemodialyzed patients (CHP). Aim. To determine the association between body fluid status and central and peripheral arterial stiffness levels. Methods. Arterial stiffness was assessed in 65 CHP by measuring the pulse wave velocity (PWV) in a central arterial pathway (carotid-femoral) and in a peripheral pathway (carotid-brachial). A blood pressure-independent regional arterial stiffness index was calculated using PWV. Volume status was assessed by whole-body multiple-frequency bioimpedance. Patients were first observed as an entire group and then divided into three different fluid status-related groups: normal, overhydration, and dehydration groups. Results. Only carotid-femoral stiffness was positively associated (P < 0.05) with the hydration status evaluated through extracellular/intracellular fluid, extracellular/Total Body Fluid, and absolute and relative overhydration. Conclusion. Volume status and overload are associated with central, but not peripheral, arterial stiffness levels with independence of the blood pressure level, in CHP.

Introduction. An altered endothelial function (EF) could be associated with preeclampsia (PE). However, more specific and complementary analyses are required to confirm this topic. Flow-mediated dilation (FMD), low-flow-mediated constriction (L-FMC), and hyperemic-related changes in carotid-radial pulse wave velocity (PWVcr) offer complementary information about "recruitability" of EF. Objectives. To evaluate, in healthy and hypertensive pregnant women (with and without PE), central arterial parameters in conjunction with "basal and recruitable" EF. Methods. Nonhypertensive (HP) and hypertensive pregnant women (gestational hypertension, GH; preeclampsia, PE) were included. Aortic blood pressure (BP), wave reflection parameters (AIx@75), aortic pulse wave velocity (PWVcf) and PWVcr, and brachial and common carotid stiffness and intima-media thickness were measured. Brachial FMD and L-FMC and hyperemic-related change in PWVcr were measured. Results. Aortic BP and AIx@75 were elevated in PE. PE showed stiffer elastic but not muscular arteries. After cuff deflation, PWVcr decreased in HP, while GH showed a blunted PWVcr response and PE showed a tendency to increase. Maximal FMD and L-FMC were observed in HP followed by GH; PE did not reach significant arterial constriction. Conclusion. Aortic BP and wave reflections as well as elastic arteries stiffness are increased in PE. PE showed both "resting and recruitable" endothelial dysfunctions.

The increase of arterial stiffness has been to have a significant impact on predicting mortality in end-stage renal disease patients. Pulse wave velocity (PWV) is a noninvasive, reliable parameter of regional arterial stiffness that integrates the vascular geometry and arterial wall intrinsic elasticity and is capable of predicting cardiovascular mortality in this patient population. Nevertheless, reports on PWV in dialyzed patients are contradictory and sometimes inconsistent: some reports claim the arterial wall stiffness increases (i.e., PWV increase), others claim that it is reduced, and some even state that it augments in the aorta while it simultaneously decreases in the brachial artery pathway. The purpose of this study was to analyze the literature in which longitudinal or transversal studies were performed in hemodialysis and/or peritoneal dialysis patients, in order to characterize arterial stiffness and the responsiveness to renal replacement therapy.

Introduction. Flow-mediated dilation (FMD), low flow-mediated constriction (L-FMC), and reactive hyperemia-related changes in carotid-to-radial pulse wave velocity (ΔPWVcr%) could offer complementary information about both "recruitability" and "resting" endothelial function (EF). Carotid-to-femoral pulse wave velocity (PWVcf) and pulse wave analysis-derived parameters (i.e., AIx@75) are the gold standard methods for noninvasive evaluation of aortic stiffness and central hemodynamics. If healthy pregnancy is associated with both changes in resting and recruitable EF, as well as in several arterial parameters, it remains unknown and/or controversial. Objectives. To simultaneously and noninvasively assess in healthy pregnant (HP) and nonpregnant (NP) women central parameters in conjunction with "basal and recruitable" EF, employing new complementary approaches. Methods. HP (n = 11, 34.2 ± 3.3 weeks of gestation) and age- and cardiovascular risk factors-matched NP (n = 22) were included. Aortic blood pressure (BP), AIx@75, PWVcf, common carotid stiffness, and intima-media thickness, as well as FMD, L-FMC, and ΔPWVcr %, were measured. Results. Aortic BP, stiffness, and AIx@75 were reduced in HP. ΔPWVcr% and FMD were enhanced in HP in comparison to NP. No differences were found in L-FMC between groups. Conclusion. HP is associated with reduced aortic stiffness, central BP, wave reflections, and enhanced recruitable, but not resting, EF.

There is a relationship between the intra-aortic balloon pumping (IABP) benefits and the dynamic behavior of muscular arteries, which is associated with induced changes on the vessel walls through an endothelial-dependent mechanism. The arterial wall elastic behavior is influenced by adventitial function; however, no studies were performed in order to elucidate if this layer plays a role in the changes determined by IABP. Our aim was to quantify acute IABP effects on the mechanical properties of muscular arteries in induced acute heart failure (AHF), before and after adventitia removal. Pressure and diameter were recorded in the iliac arteries (IA) of sheep (n = 7), before and during 1:2 IABP: (i) in control state (CS) with intact IA, (ii) in CS after IA adventitia removal, and (iii) in de-adventitialized IA after AHF. Conduit function, compliance and arterial distensibility were calculated in each state. During CS, IABP resulted in intact IA dilatation and in an increase in conduit function, compliance and distensibility; adventitial removal determined an increase of arterial stiffness with respect to the CS, which decreased when IABP was used; the increase in arterial stiffness observed after adventitia removal was also detected in AHF state; IABP improves conduit function and arterial stiffness in de-adventitialized arteries, both before and during AHF. However, the improvement in these properties was lower than in intact arteries. Before and after AHF induction, the improvements of conduit function and arterial distensibility determined by IABP in intact IA were significantly reduced after adventitia removal. Adventitial layer integrity would be necessary to maximize IABP-related beneficial effects on arterial system properties., (© 2013 Wiley Periodicals, Inc. and International Center for Artificial Organs and Transplantation.)

Background: Cardiac resynchronization therapy (CRT) has benefits on left ventricle (LV) performance, but its mid-term effects on LV load and LV-arterial coupling are unknown., Aims: To evaluate CRT mid-term effects on LV-arterial coupling, arterial load and its determinants, and the association between CRT-dependent aortic haemodynamic changes and the arterial biomechanics., Methods and Results: Cardiac and aortic echographies were done in 25 patients (age: 61 ± 12 years; 14 men; New York Heart Association functional classes III-IV; LV ejection fraction = 28 ± 7%, QRS = 139 ± 20 ms) before and after (23 ± 12 days) CRT. Standard structural and functional parameters and dyssynchrony indices were evaluated. Ascending aorta flow and diameter waveforms were measured. Central pressure was derived using a transfer function and the diameter calibration method. Calculus: arterial elastance (EA); aortic impedance (Zc) and distensibility (AD); systemic resistances (SVR), total compliance (CT); global reflection coefficient; LV end-systolic elastance (EES); and LV-arterial coupling (EA/EES). After CRT EA diminished (-30%;P = 0.001), EES increased (29%; P = 0.001) and EA/EES improved (pre-CRT: 2.9 ± 0.9, post-CRT: 1.6 ± 0.7; P = 0.001). Arterial elastance changes were associated with changes in arterial properties. Cardiac resynchronization therapy was associated with pressure-independent increase in mean aortic diameter (pre-CRT: 30.0 ± 4.0 mm, post-CRT: 33.0 ± 5.1 mm; P = 0.005) and distensibility (pre-CRT: 3.8 ± 2.6 × 10(-3)mmHg(-1), post-CRT: 6.4 ± 2.5 × 10(-3) mmHg(-1); P = 0.002), and Zc reduction (pre-CRT: 3.5 ± 1.8 × 10(-2)mmHg.s/mL, post-CRT:1.9 ± 0.8 × 10(-2) mmHg.s/mL; P = 0.001) and SVR (pre-CRT:1.7 ± 0.4 mmHg.s/mL, post-CRT:1.0 ± 0.3 mmHg.s/mL; P = 0.001). Changes in EA determinants were associated with changes in aortic flow., Conclusion: Early after CRT central and peripheral arterial biomechanics improved, determining a pressure-independent increase in aortic diameter and a reduction in arterial load. Left ventricular systolic performance and LV-arterial coupling were enhanced. Arterial biomechanical changes were associated with aortic flow changes.

The mechanisms that explain intra-aortic balloon pumping (IABP) effects are not completely understood, and attributing them only to pressure-associated changes in cardiac function would be an oversimplification. Since IABP modifies the aortic and systemic blood-flow pattern, flow-related effects could be expected. To characterize effects of acute heart failure (AHF) on the arterial biomechanics; IABP effects on the arterial biomechanics during AHF, and their potential time-dependence; the association between hemodynamics and biomechanical changes during AHF and IABP. Sheep (n = 6) aortic pressure, flow, and diameter were measured: (1) before (Basal) and (2) 1-3 (HF(1-3)) and 28-30 (HF(28-30)) min after starting halothane to induce AHF; and (3) at specific times (1-3, 14-15 and 28-30 min) during IABP assistance. Calculus: aortic characteristic impedance (Z(c)), beta stiffness (β), incremental (E(INC)) and pressure-strain elastic modulus (E(P)); total arterial compliance (C(G)), total systemic vascular resistance and wave propagation parameters. (1) AHF resulted in an acute increase in aortic and systemic stiffness (HF(28-30) % changes with respect to Basal conditions: β +217%, E (P) +143%, E(INC) +101%, Z(c) +52%, C(G) -13%), associated with the reduction in the aortic blood flow; (2) during AHF IABP resulted in acute beneficial changes aortic and systemic biomechanics (% changes in IABP(1-3) with respect HF(28-30): β -62%, E(P) -68%, E (INC) -66%, Z(c) -38%, C(G) 66%), and in wave propagation parameters, (3) IABP-related changes were time-dependent and associated with changes in aortic blood flow. Aortic and systemic biomechanical and impedance properties are detrimentally modified during AHF, being the changes rapidly reverted during IABP. IABP-related beneficial changes in arterial biomechanics were time-dependent and associated with IABP capability to increase blood flow.

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.)

Unlabelled: Carotid intima-media thickness (CIMT) is a well-established subclinical marker of atherosclerosis. Non-invasive vascular evaluation has emerged as a useful tool to aid in individual cardiovascular (CV) risk stratification and diagnose. The use of CIMT in CV risk stratification requires knowing the expected reference values for the population studied. Our aim were: a) to evaluate the relationship between aging and CIMT, b) to analyze gender and side (right vs left) related-differences in CIMT and c) to determine the CIMT reference values for an Uruguayan population taking into account aging-related CIMT changes., Methods: 367 asymptomatic subjects without known CV disease or risk factors were included in the study. Subjects were divided into six age groups. High-resolution B-mode ultrasound images of both (right and left) common carotid arteries were obtained based on the techniques and recommendations described in international consensus., Results: No significant age-related differences in CIMT between men and women were observed. The mean left CIMT was thicker compared with right CIMT in groups 4, 5 and 6. However, there were no significant differences in those groups. The nomogram model was constructed from data base, in which the 95% confidence interval was considered. Diagnosis thresholds were determined as well., Conclusion: We define reference values of CIMT for our population using gold standard techniques which contributes to standard techniques which contributes to an improved insight into clinical practice and can be used routinely for evaluation.

Purpose. To evaluate in chronically haemodialysed patients (CHPs), if: (1) the vascular access (VA) position (upper arm or forearm) is associated with differential changes in upper limb arterial stiffness; (2) differences in arterial stiffness exist between genders associated with the VA; (3) the vascular substitute (VS) of choice, in biomechanical terms, depends on the previous VA location and CHP gender. Methods. 38 CHPs (18 males; VA in upper arm: 18) were studied. Left and right carotid-brachial pulse wave velocity (PWV(c-b)) was measured. In in vitro studies, PWV was obtained in ePTFE prostheses and in several arterial and venous homografts obtained from donors. The biomechanical mismatch (BM) between CHP native vessel (NV) and VS was calculated. Results/Conclusions. PWV(c-b) in upper limbs with VA was lower than in the intact contralateral limbs (P < 0.05), and differences were higher (P < 0.05) when the VA was performed in the upper arm. Differences between PWV(c-b) in upper limbs with VA (in the upper arm) with respect to intact upper limbs were higher (P < 0.05) in males. Independently of the region in which the VA was performed, the homograft that ensured the minimal BM was the brachial artery. The BM was highly dependent on gender and the location in the upper limb in which the VA was performed.

Carotid-to-radial pulse wave velocity (PWV(cr)) has been proposed to evaluate endothelial function. However, the measurement of PWV(cr) is not without limitations. A new simple approach could have wide application. Stiffness index (SI) is obtained by analysis of the peripheral pulse wave and gives reproducible information about stiffness of large arteries. This study assessed the effects of hyperemia on SI and compared it with PWV(cr) in 14 healthy subjects. Both were measured at rest and during 8 minutes after ischemia. SI temporal course was determined. At 1 minute, SI and PWV(cr) decreased (5.58 ± 0.24 to 5.34 ± 0.23 m/s, P < 0.05; 7.8 ± 1.0 to 7.2 ± 0.9 m/s; P < 0.05, resp.). SI was positively related to PWV(cr) in baseline (r = 0.62 , P < 0.05), at 1 minute (r = 0.79, P < 0.05), and during the whole experimental session (r = 0.52, P < 0.05). Conclusion. Hyperemia significantly decreases SI in healthy subjects. SI was related to PWV(cr) and could be used to facilitate the evaluation of hyperemia-related changes in arterial stiffness.

Unlabelled: Preeclampsia/eclampsia syndrome, a major cause of maternal mortality and morbidity, has been recognized as a condition with a globally impaired endothelial function (EF). The possibility of identifying early subclinical endothelial damage during pregnancy could be of value in classifying the different hypertensive states of pregnancy, and have a positive impact in the understanding of this syndrome, as well as on the appropriate treatment of these patients. Reactive hyperemia-related changes in carotid-radial pulse wave velocity (PWVcr) were proposed as an alternative tool for the evaluation of EF in patients with cardiovascular risk factors. If impaired EF, which follows hypertensive disorders of pregnancy can be assessed using PWVcr changes remains still unknown., Aims: To assess and compare reactive hyperemia-related changes in PWVcr and FMD in pregnant women (healthy and with hypertensive disorders) and non pregnant women., Methods: Healthy pregnant (HP; n=13), preeclamptic (PE; n=7), non-proteinuric hypertensive (NPH; n=6) and non-pregnant (NP; n=32) women were included. Left PWVcr (strain gauge mechano-transducers), left brachial arterial diameter (B-Mode ultrasound) and blood flow velocity (Doppler ultrasound) were measured before (baseline) and after the transient ischemia of the left forearm were determined., Results: One minute after the cuff deflation, PWVcr decreased in HP (6.9 ± 1.5 to 6.0 ± 0.9 m/s, p&#60;0.001) and in NP (8.1 ± 0.9 to 7.4 ± 0.9 m/s; p&#60;0.001). NPH showed a blunted hyperemic PWVcr response (6.6 ± 1.4 to 6.7 ± 1.0 m/s; p=0.91), whereas PE showed a tendency to increase (6.0 ± 0.7 to 6.4 ± 0.8 m/s; p=0.10). Reactive hyperemia PWVcr response (ΔPWVcr in %) differed comparing HP with NPH (-12% vs. +2%; p&#60;0.01) and with PE (-12 vs. +6%; p &#60;0.01), whereas no differences were found between NHP and PE (p=1.00)., Conclusion: HP showed an enhanced PWVcr reduction, whereas PE and NPH showed a blunted hyperemic PWVcr response. Carotid-radial PWVcr analysis could have a potential role in the assessment of pregnancy to study EF with a potential clinical application in predicting pregnancy induced hypertension and preeclampsia.

Carotid-femoral pulse wave velocity (PWV) has emerged as the gold standard for non-invasive evaluation of aortic stiffness; absence of standardized methodologies of study and lack of normal and reference values have limited a wider clinical implementation. This work was carried out in a Uruguayan (South American) population in order to characterize normal, reference, and threshold levels of PWV considering normal age-related changes in PWV and the prevailing blood pressure level during the study. A conservative approach was used, and we excluded symptomatic subjects; subjects with history of cardiovascular (CV) disease, diabetes mellitus or renal failure; subjects with traditional CV risk factors (other than age and gender); asymptomatic subjects with atherosclerotic plaques in carotid arteries; patients taking anti-hypertensives or lipid-lowering medications. The included subjects (n = 429) were categorized according to the age decade and the blood pressure levels (at study time). All subjects represented the "reference population"; the group of subjects with optimal/normal blood pressures levels at study time represented the "normal population." Results. Normal and reference PWV levels were obtained. Differences in PWV levels and aging-associated changes were obtained. The obtained data could be used to define vascular aging and abnormal or disease-related arterial changes.

Intra-aortic balloon pump (IABP) benefits could depend on variations in the cardiovascular biomechanical properties associated with blood flow-induced endothelium-dependent changes. However, if IABP results in changes in the peripheral artery biomechanics and if the endothelium plays a role in these potential changes remains unknown. The aim of this study is to characterize acute IABP effects on peripheral artery biomechanics in control and acute heart failure (AHF) states and the role of the endothelium in IABP effects on peripheral artery biomechanics. Pressure and diameter were recorded in sheep (n= 7) iliac arteries (IAs), before and during 1:2 IABP, during four states: (i) control with intact IA; (ii) AHF with intact IA; (iii) control with de-endothelialized (DE) (mechanical rubbing) IA; and (iv) AHF with DE IA. Arterial distensibility, elastic modulus, and conduit function (CF) (1/characteristic impedance) were calculated. The results of this study include: (i) during control conditions, IABP resulted in intact IA dilatation, stiffness reduction, and CF increase; (ii) AHF induction determined a reduction in intact IA diameter and CF, and a stiffness increase. These changes reverted during IABP; (iii) the increase in IA stiffness observed after DE remained unchanged during IABP; (iv) in DE IA, AHF did not result in diameter or stiffness changes; and (v) IABP during AHF did not associate changes in diameter or stiffness in the DE IA. In conclusion, during control and AHF states, IABP results in IA dilatation and stiffness reduction. The integrity of the endothelial layer would be critical for the IABP-associated changes in IA biomechanics., (© 2011, Copyright the Authors. Artificial Organs © 2011, International Center for Artificial Organs and Transplantation and Wiley Periodicals, Inc.)

A better understanding of the biomechanical properties of the arterial wall provides important insight into arterial vascular biology under normal (healthy) and pathological conditions. This insight has potential to improve tracking of disease progression and to aid in vascular graft design and implementation. In this study, we use linear and nonlinear viscoelastic models to predict biomechanical properties of the thoracic descending aorta and the carotid artery under ex vivo and in vivo conditions in ovine and human arteries. Models analyzed include a four-parameter (linear) Kelvin viscoelastic model and two five-parameter nonlinear viscoelastic models (an arctangent and a sigmoid model) that relate changes in arterial blood pressure to the vessel cross-sectional area (via estimation of vessel strain). These models were developed using the framework of Quasilinear Viscoelasticity (QLV) theory and were validated using measurements from the thoracic descending aorta and the carotid artery obtained from human and ovine arteries. In vivo measurements were obtained from 10 ovine aortas and 10 human carotid arteries. Ex vivo measurements (from both locations) were made in 11 male Merino sheep. Biomechanical properties were obtained through constrained estimation of model parameters. To further investigate the parameter estimates, we computed standard errors and confidence intervals and we used analysis of variance to compare results within and between groups. Overall, our results indicate that optimal model selection depends on the artery type. Results showed that for the thoracic descending aorta (under both experimental conditions), the best predictions were obtained with the nonlinear sigmoid model, while under healthy physiological pressure loading the carotid arteries nonlinear stiffening with increasing pressure is negligible, and consequently, the linear (Kelvin) viscoelastic model better describes the pressure-area dynamics in this vessel. Results comparing biomechanical properties show that the Kelvin and sigmoid models were able to predict the zero-pressure vessel radius; that under ex vivo conditions vessels are more rigid, and comparatively, that the carotid artery is stiffer than the thoracic descending aorta; and that the viscoelastic gain and relaxation parameters do not differ significantly between vessels or experimental conditions. In conclusion, our study demonstrates that the proposed models can predict pressure-area dynamics and that model parameters can be extracted for further interpretation of biomechanical properties.

Unlabelled: Carotid-femoral pulse wave velocity (PWV) has emerged as the gold standard for non-invasive evaluation of aortic stiffness. However, the absence of standardized methodologies of study and lack of normal and references values have limited wider implementation of PWV in clinical practice. In this work normal PWV levels were determined in a Uruguayan population and the obtained values were analyzed taking into account data from other populations. The differences between the 'real' PWV levels and the PWV calculated using different wave detection algorithms and path lengths were assessed, and compared the taking into account the changes in PWV with aging., Results: The Uruguayan population showed a rate of PWV increase comparable to that reported previously in non-hypertensive European subjects, although overall, PWV values were approximately 2 m/s higher in the Uruguayan population. The different approaches used to calculate the PWV showed differences in their availability to follow aging-variations in 'adjusted' (or 'real') PWV.

Unlabelled: Flow-mediated dilatation (FMD) is the most accepted technique for the evaluation of endothelial function. However, it has been show a great inter-subject variability limiting its clinical use. Carotid-radial pulse wave velocity (PWVcr) was proposed as an alternative tool for the evaluation of endothelial function. At the present, there is no doubt that PWVcr reduces its values in response to reactive hyperemia test (RHT) in healthy subjects., Aims: a) to determine simultaneously the temporal profile of FMD, PWVcr and shear rate in response to RHT and b) to describe and analyze how subjects "FMD responders" or "non-responders" behave regards to PWVcr changes., Methods: 34 Healthy young subjects were included. The PWVcr (strain gauge mechanotransducers), brachial diameter (B-Mode ultrasound and blood flow velocity (Doppler ultrasound) were measured before (baseline) the cuff was inflated and after its deflation (5 minutes). 10(th) percentiles FMD and PWVcr changes in the population were used for the definition of the subjects ("responders and non-responders")., Results: Changes in PWVcr, brachial arterial diameter and shear rate were evidenced after the cuff release (p<0.05). There were differences in the PWV and FMD temporal profiles. Within "FMD responders" there were "PWV responders and non-responders"., Conclusion: Assessing RHT-related changes in PWVcr in the context of a FMD evaluation, could be useful as a discriminator of intrinsic wall alterations giving additional information of vascular dynamics.

This work was carried out in a Uruguayan (South American) population to characterize aging-associated physiological arterial changes. Parameters markers of subclinical atherosclerosis and that associate age-related changes were evaluated in healthy people. A conservative approach was used and people with nonphysiological and pathological conditions were excluded. Then, we excluded subjects with (a) cardiovascular (CV) symptoms, (b) CV disease, (c) diabetes mellitus or renal failure, and (d) traditional CV risk factors (other than age and gender). Subjects (n = 388) were submitted to non-invasive vascular studies (gold-standard techniques), to evaluate (1) common (CCA), internal, and external carotid plaque prevalence, (2) CCA intima-media thickness and diameter, (3) CCA stiffness (percentual pulsatility, compliance, distensibility, and stiffness index), (4) aortic stiffness (carotid-femoral pulse wave velocity), and (5) peripheral and central pressure wave-derived parameters. Age groups: ≤20, 21-30, 31-40, 41-50, 51-60, 61-70, and 71-80 years old. Age-related structural and functional vascular parameters profiles were obtained and analyzed considering data from other populations. The work has the strength of being the first, in Latin America, that uses an integrative approach to characterize vascular aging-related changes. Data could be used to define vascular aging and abnormal or disease-related changes.

Gender-related difference in cardiovascular diseases is one of the most investigated and still unsolved issues. Finding an explanation to this topic might have important implications for the understanding of the differences between men and women in diseases and possibly lead to the development of gender-specific strategies for its management. Recent studies have proposed that the capacitive or reservoir function of the aorta and large elastic arteries plays a major role in determining the pulse wave morphology. The pressure waveform can be explained in terms of a reservoir pressure related to arterial compliance and an "excess" or wave-related pressure associated with traveling waves. Gender-differences in the ascending aorta pressure waveform reservoir and excess components are to be characterized. The aim of this study was to evaluate, by means of a mathematical approach, gender-related differences in the central aortic pressure waveform components. Central aortic pressure waveform was non-invasively obtained in 22 healthy subjects (Age: 20 years old; 11 female). Males and females showed differences in the level and time to maximal excess pressure component, but no gender-related differences were found in the reservoir one.

In this work we present an initiative to develop a national (Uruguayan) program to evaluate vascular age and to detect pre-clinical atherosclerosis using: gold-standard technologies; complimentary and integrative approaches to asses arterial functional and structural indexes; data bases systems to process, analyze and determine normal and reference values and to identify the most sensitive markers of vascular changes for different ages. We evaluated, in a Uruguayan population complementary structural and functional vascular parameters that associate aging-related changes and are considered markers of sub-clinical atherosclerosis. Traditional CV risk factors were assessed. The subjects (n=281) were submitted to non-invasive vascular studies to evaluate: 1) Common carotid artery (CCA) intima-media thickness and diameter waveforms, 2) CCA stiffness, 3) aortic stiffness (pulse wave velocity) and 4) peripheral and central pressure pulse wave derived parameters. Age groups: 21-30, 31-40, 41-50, 51-60, and 61-70 years-old. Age-related profiles were obtained for the different vascular parameters, and their utility to assess vascular changes in young, middle-aged and old subjects was evaluated. The work has the strength of being the first that uses, in Latin-America an integrative approach to characterize vascular aging-related changes.

Study of humans aging has presented difficulties in separating the aging process from concomitant disease and/or in defining normality and abnormality during its development. In accordance with this, aging associates structural and functional changes evidenced in variations in vascular parameters witch suffer alterations during atherosclerosis and have been proposed as early markers of the disease. The absence of adequate tools to differentiate the expected (normal) vascular changes due to aging from those related with a vascular disease is not a minor issue. For an individual, an early diagnosis of a vascular disease should be as important as the diagnosis of a healthy vascular aging. Recent studies have proposed that the capacitive or reservoir function of the aorta and large elastic arteries plays a major role in determining the pulse wave morphology. The arterial pressure waveform can be explained in terms of a reservoir pressure, related to the arterial system compliance, and an "excess" or wave-related pressure, associated with the traveling waves. The aim of this study was to evaluate, by means of a mathematical approach, age-related changes in measured, reservoir and excess central aortic pressure in order to determine if age-related changes are concentrated in particular decades of life. Central aortic pressure waveform was non-invasively obtained in healthy subjects (age range: 20-69 years old). Age-related profiles in measured, reservoir and excess pressure were calculated.

Simultaneous measurement of pressure and diameter in blood vessels or vascular prosthesis is of great importance in cardiovascular research. Knowledge of diameter changes as response to intravascular pressure is the basis to estimate the biomechanical properties of blood vessel. In this work a new method to quantify arterial diameter based in high resolution ultrasonography is proposed. Measurements on an arterial phantom placed on a cardiovascular simulator were performed. The results were compared to sonomicrometry measurements considered as gold standard technique. The obtained results indicate that the new method ensure an optimal diameter quantification. This method presents two main advantages respect to sonomicrometry: is noninvasive and the vessel wall strain can be measured directly.

This study aimed to characterize the following: (i) in chronically hemodialyzed subjects (CHDSs), with and without diabetic nephropathy (DN), and in healthy subjects (non-CHDSs) different arterial pathways stiffness to determine potential pathology-dependent, etiology- and/or pathway-dependent differences; and (ii) the biomechanical mismatch (BM) between arteries from non-CHDSs or CHDSs (with and without DN) and arterial cryografts, venous cryografts, and synthetic prosthesis to determine arterial pathway, pathology, and/or etiology-related differences in the substitute of election in terms of BM. Carotid-femoral and carotid-brachial pulse wave velocity (PWV) were measured in 30 non-CHDSs and 71 CHDSs (11 with DN). In addition, PWV was measured in arterial (elastic and muscular) and venous cryografts and in expanded polytetrafluorethylene prosthesis. The arterial pathways regional differences and the subjects' arterial pathways-substitutes BM were calculated. Arterial stiffness levels and regional differences were higher in CHDS than in non-CHDS. Among CHDS, those with DN showed higher stiffness in the aorto-femoral pathway and larger regional differences. Cryografts showed always the least BM. Non-CHDS and CHDS differed in the cryograft of election. In CHDS, the BM was related with the cryograft type, arterial pathway, and renal disease etiology. The BM could be minimized, selecting the most adequate cryograft type, taking into account the recipient specific characteristic (i.e., arterial pathway and renal disease etiology).