Cintia Galli

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 (PWVc-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. PWVc-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 PWVc-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.

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.

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.

Structural and Functional Properties of Venous Wall: Relationship between Elastin, Collagen, and Smooth Muscle Components and Viscoelastic Properties

The aims of this work were (1) to analyze the viscoelastic behavior of different venous segments and their differences, considering the structural characteristics (elastin, collagen, and smooth muscle content) of the venous wall; (2) to analyze the venous biomechanical behavior by means of the histological characteristics of the veins. Nine healthy male Corriedale sheep were included. One vein was selected from each animal to evaluate its biomechanical properties: (a) anterior vena cava, (b) right jugular vein, and (c) right femoral vein. Each selected vein was instrumented with pressure and diameter sensors. After excision, a small ring-shaped sample was set apart from each segment for histological analysis. The amounts of elastin, collagen and smooth muscle were correlated to calculated biomechanical parameters (high- and low-pressure compliance and viscosity). Conclusions are the following: (1) the viscoelastic behavior of the venous wall varies depending on the vascular territory, and it is associated with the variation of the histological structure. These differences involve muscle (both smooth and striated), elastin, and collagen contents. (2) In addition, the quantity of collagen was negatively correlated with high- and low-pressure compliances, and (3) the smooth muscle content was higher in peripheral veins and is positively correlated with venous wall viscosity.

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.

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.

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 Pearsons 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.

PS 05-58 ARTERIAL HYPERTENSION AND PULSE PRESSURE: RELATIONSHIP WITH PULSE WAVE VELOCITY.

Objective: Pulse Pressure (PP) and pulse wave velocity (PWV) are related to cardiovascular risk (CVR). We evaluated in patients with arterial hypertension (HT), as unique risk factor, the impact of arterial hypertension on PP and PWV, the mean and age related PWV values, the relationship between PP and PWV and the rate of changes with aging. Design and Method: 1079 subjects were randomly enrolled and 299 selected as selected as asymptomatic non-smoking hypertensive patients (HT; 50 ± 14.8years old), as the only risk factor. Blood pressure was measured in the sitting position, after 10 min rest, 3 times (Omron model 705IT), elapsed by 1 min. After that, PP was calculated as: SBP-DBP. The mean value was considered as the PP value for each subject. Carotid-femoral PWV was measurements were performed continuously for at least 10 cardiac cycles and the mean value considered as PWV value for each patient. Results: In HT, mean PWV value was 8.04 ± 1.8 m/s and increased linearly with age (r = 0.49; p < 0.001) being the year growing of 0.062 ± 0.006 m/sec (p < 0.001) without. In HT, PP increases linearly with aging (r = 0.155; p < 0.01) with a progressive year related increase (0.138 ± 0.051 mmHg/year; P < 0.001). No gender differences were found (56.31 ± 12.89 mmHg versus 54.58 ± 13.62 mmHg; p = 0.338). Finally, PWV and PP in HT showed a significant positive correlation (r = 0.191, p < 0.001). Conclusions: All these data suggest that, in HT patients, PP, as PWV, could be a reliable marker of arterial dysfunction. This is supported by the fact that PP and Arterial stiffness, evaluated as PWV are age dependent without differences in gender and were significantly related.

PS 05-59 Pulse Wave Velocity and Carotid Intima Medial Thickness: Age and Arterial Hypertension Related Alterations.

Objective: Carotid artery intima-media thickness (CCIMT) and pulse wave velocity (PWV) are considered as surrogates of arterial stiffness and related to cardiovascular risk (CVR). To analyze, in normotensive subjects (NT), without CVR: the age related normal values for CCIMT and PWV, their relationship and the rate of changes with aging. In subjects with arterial hypertension (HT), as unique risk factor (RF), the age and hypertension impact on PWV and CCIMT. Design and Method: 1079 subjects were randomly enrolled and divided in asymptomatic non-smoking NT (n = 780, 40 ± 8.5 years old), without diabetes, dyslipidemia and first degree family history of hypertension and asymptomatic non-smoking HT, as only RF, (n = 299, 50 ± 14.8 years old). In 611 out of the 1079 subjects included (39.8 ± 16.5 years), the reference values of CCIMT and the 95% confidence intervals values were also calculated for each decade of age (10–81 years). Carotid-Femoral PWV was continuously measured for, at least 10 cardiac cycles, and the mean value considered as the subject PWV. CCIMT was measured with a B mode ultrasound echocardiograph (EsaoteMyLab 40) with specific software. Results: In NT, mean PWV value was 6.85 ± 1.66 m/s with a linear increase related with age (r = 0.79; p < 0.05) and a decade growth of 0.245 m/sec. Similarly, CCIMT mean value was 0.554 ± 0.130 mm and increases linearly with aging (r = 0.79; p < 0.05), with a progressive decade related increase (0.06 ± 0.001 mm). In HT, mean PWV value was 8.04 ± 1.8 m/s (p < 0.01) and, as in NT, increased linearly with age (r = 0.49; p < 0.05) with a decade growing of 0.589 m/sec (p < 0.001). PWV and IMT were significantly related (r = 0.42, p < 0.001). No gender differences were observed either in NT or HT. Conclusions: It is suggest that CVR related to the ageing process is further increased when other RF, as arterial hypertension, are added.