Central-To-Peripheral Arterial Stiffness Gradient in Hemodialyzed Patients Depends on the Location of the Upper-limb Vascular Access.

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.

Aortic-Radial Pulse Wave Velocity Ratio in End-stage Renal Disease Patients: Association with Age, Body Tissue Hydration Status, Renal Failure Etiology and Five Years of Hemodialysis.

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.

Hemodialysis Decreases the Etiologically-Related Early Vascular Aging Observed in End-Stage Renal Disease: A 5-Year Follow-Up Study.

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.

Hydration Status Is Associated with Aortic Stiffness, but Not with Peripheral Arterial Stiffness, in Chronically Hemodialysed Patients.

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.

Arterial Stiffness and Renal Replacement Therapy: A Controversial Topic.

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.

Arterial Stiffness in a Rural Population of Argentina: Pilot Study.

INTRODUCTION: Aortic stiffness evaluated through pulse wave velocity (PWV) measurement is nowadays accepted as a reliable parameter to estimate cardiovascular risk. However the data about arterial stiffness in South America come from urban populations. AIMS: To determine the relationship between PWV changes and ageing and to identify the rate of change in each decade of life. METHODS: PWV was measured in the carotid-femoral pathway in 400 inhabitants of Vela town and clinical parameters were recorded. RESULTS: The prevalence of hypertension, dyslipidemia and diabetes was 33.5, 17.5, 5% respectively. PWV was positively correlated with age (r: 0.817, p = 0.01) and was greater after the fifth decade of life (9.72 ± 2.2 vs. 5.87 ± 1.55 m/s; p: 0.001) than in youngers than 50 years, respectively. The risk (odds ratio) of having PWV >10 m/s was higher in hypertensives (OR: 50, p = 0.001), older than 50 years (OR: 44, p = 0.001), diabetics (OR 9.5, p = 0.001) and dyslipidemic patients (OR: 5, p = 0.001). CONCLUSIONS: This is the first study in a rural population of Argentina which determines the relationship of PWV with age and cardiovascular risk. PWV shows a slower growth in subjects less than 50 years compared to older adults with a strong relationship to the process of arterial aging, the development of hypertension and cardiovascular risk.

Corrigendum to "reference values of pulse wave velocity in healthy people from an urban and rural argentinean population".

[This corrects the article DOI: 10.1155/2014/653239.].

Hemodialysis decreases carotid-brachial and carotid-femoral pulse wave velocities: A 5-year follow-up study.

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.

Reference values of pulse wave velocity in healthy people from an urban and rural argentinean population.

In medical practice the reference values of arterial stiffness came from multicenter registries obtained in Asia, USA, Australia and Europe. Pulse wave velocity (PWV) is the gold standard method for arterial stiffness quantification; however, in South America, there are few population-based studies. In this research PWV was measured in healthy asymptomatic and normotensive subjects without history of hypertension in first-degree relatives. Normal PWV and the 95% confidence intervals values were obtained in 780 subjects (39.8 ± 18.5 years) divided into 7 age groups (10-98 years). The mean PWV found was 6.84 m/s ± 1.65. PWV increases linearly with aging with a high degree of correlation (r (2) = 0.61; P < 0.05) with low dispersion in younger subjects. PWV progressively increases 6-8% with each decade of life; this tendency is more pronounced after 50 years. A significant increase of PWV over 50 years was demonstrated. This is the first population-based study from urban and rural people of Argentina that provides normal values of the PWV in healthy, normotensive subjects without family history of hypertension. Moreover, the age dependence of PWV values was confirmed.

Vascular accesses for haemodialysis in the upper arm cause greater reduction in the carotid-brachial stiffness than those in the forearm: study of gender differences.

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.

Vascular cryografts offer better biomechanical properties in chronically hemodialyzed patients: role of cryograft type, arterial pathway, and diabetic nephropathy as matching determinants.

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).

Vascular access localization determines regional changes in arterial stiffness.

BACKGROUND: Vascular access (VA) dysfunction is a common cause of hospitalization in chronically hemodialyzed patients (CHP) limiting the improvement in health and has been largely studied in order to decrease the morbidity events that involves both the artery and the vein used in the construction of the fistula. In parallel, patients in end-stage renal failure show an increase in arterial stiffness. AIM: The aims of this work were: (a) to evaluate arterial stiffness through pulse wave velocity (PWV) measurements in the carotid-brachial pathway where the arteriovenous fistulae (AVF) was constructed, and (b) to determine possible differences in arterial stiffness between the carotid-brachial pathway with and without VA. METHODS: PWV, clinical and biochemical parameters were measured in 38 CHP. PWV was obtained in the carotid-femoral, and in the left and right carotid-brachial pathway. RESULTS: Carotid-brachial PWV determination in upper limbs with AVF (10.07 +/- ;2.43 m/s) showed significantly lower values than those observed in the contra-lateral arm without VA (11.55 +/- ;2.27 m/s). Curiously, the PWV value observed in arms with an AVF was significantly lower in diabetic than in non-diabetic hemodialyzed patients (NDHP) (8.00 +/- ;2.86 m/s and 10.38 +/- ;2.33 m/s; respectively). Measurements of PWV in the carotid-femoral pathway in CHP showed a mean value of 14.09 +/- ;3.12 m/s. Carotid-femoral PWV in NDHP (14.06 +/- ;2.44 m/s) was significantly lower than that observed in the diabetic patients (16.87 +/- ;3.42 m/s). CONCLUSIONS: Carotid-brachial PWV values obtained in the upper limbs, in which VAs were constructed, were significantly lower than that measured in intact arteries in the contra-lateral pathway in CHP.

Evaluación mecánica de arterias sistémicas: análisis del rol del desacople mecánico en la génesis de vasculopatías obstructivas / Mechanical evaluation of systemic arteries: assessment of the mechanical mismatch in the development of obstructive vasculopathies

El desarrollo de hiperplasia intimal ha sido reconocido como la principal causa de mal funcionamiento de los accesos vasculares utilizados en pacientes sometidos a hemodiálisis por insuficiencia renal terminal. Lo mismo ocurre en pacientes revascularizados, ya sea usando puente con vena safena o prótesis vasculares de politetrafluoretileno expandido (ePTFE). El desacople elástico entre la arteria nativa y el injerto ha sido señalado como la causa del desarrollo de hiperplasia intimal. En este trabajo se describen los índices mas utilizados para caracterizar las propiedades mecánicas de la pared arterial. Además se reporta un análisis biomecánico de arterias, venas y prótesis de politetrafluoroetileno expandido

Evaluación mecánica de arterias sistémicas: análisis del rol del desacople mecánico en la génesis de vasculopatías obstructivas / Mechanical evaluation of systemic arteries: assessment of the mechanical mismatch in the development of obstructive vasculopathies

El desarrollo de hiperplasia intimal ha sido reconocido como la principal causa de mal funcionamiento de los accesos vasculares utilizados en pacientes sometidos a hemodiálisis por insuficiencia renal terminal. Lo mismo ocurre en pacientes revascularizados, ya sea usando puente con vena safena o prótesis vasculares de politetrafluoretileno expandido (ePTFE). El desacople elástico entre la arteria nativa y el injerto ha sido señalado como la causa del desarrollo de hiperplasia intimal. En este trabajo se describen los índices mas utilizados para caracterizar las propiedades mecánicas de la pared arterial. Además se reporta un análisis biomecánico de arterias, venas y prótesis de politetrafluoroetileno expandido

[Effect of the temperature of the dialysis bath in diabetics]. / Efecto de la temperatura del baño de hemodiálisis en diabéticos.

During the dialysis procedure, arterial hypotension is one of the most common problems and it has been object of many studies. In hemodialysis, changes are produced in body volume through ultrafiltration that generate an increase in the production of thermic energy, which is removed during the treatment. The hypovolemia resulting from the removal of volume activates the sympathetic system, avoiding in this way heat loss and increasing body temperature that promotes vascular vasodilatation and interferes with the compensatory constrictive response to volume fall with consequent arterial hypotension. Patients with autonomic neuropathy would be the most affected by volume depletion and they are usually the ones that show the highest frecuency of hypotension episodes, typical of patients with diabetes. It has been proved before that the use of a cold bath does not decrease the efficiency of the dialysis treatment and improves the cardiovascular stability as well, mostly in patients proned to it, such as diabetics, elderly, and patients with cardiac failure. In this study, it was observed that patients showed low basal temperatures before dialysis treatment and that the use of bath temperature of 35.5 degrees C increased the temperature post dialysis less than with the standard bath at 37 degrees C. The bath at 35.5 degrees C decreased the episodes of arterial hypotension, with an improvement in patient's welfare, and lower requirement of attention and treatment costs.

Efecto de la temperatura del baño de hemodiálisis en diabéticos. / [Effect of the temperature of the dialysis bath in diabetics]

During the dialysis procedure, arterial hypotension is one of the most common problems and it has been object of many studies. In hemodialysis, changes are produced in body volume through ultrafiltration that generate an increase in the production of thermic energy, which is removed during the treatment. The hypovolemia resulting from the removal of volume activates the sympathetic system, avoiding in this way heat loss and increasing body temperature that promotes vascular vasodilatation and interferes with the compensatory constrictive response to volume fall with consequent arterial hypotension. Patients with autonomic neuropathy would be the most affected by volume depletion and they are usually the ones that show the highest frecuency of hypotension episodes, typical of patients with diabetes. It has been proved before that the use of a cold bath does not decrease the efficiency of the dialysis treatment and improves the cardiovascular stability as well, mostly in patients proned to it, such as diabetics, elderly, and patients with cardiac failure. In this study, it was observed that patients showed low basal temperatures before dialysis treatment and that the use of bath temperature of 35.5 degrees C increased the temperature post dialysis less than with the standard bath at 37 degrees C. The bath at 35.5 degrees C decreased the episodes of arterial hypotension, with an improvement in patients welfare, and lower requirement of attention and treatment costs.