Pulse Wave Velocity Variability Research Articles

Local Evaluation of Variation in Pulse Wave Velocity over the Cardiac Cycle using Single-Element Ultrasound Transducer.

A method and system for single-site measurement of local pulse wave velocity (PWV) and its variation over the cardiac cycle are presented. The proposed system employs a single-element ultrasound transducer and associated custom technology to record arterial diameter and wall thickness waveforms in real-time. Simultaneously acquired blood pressure, diameter and wall thickness parameters were used to evaluate diastolic local PWV (CD) and systolic local PWV (Cs) from an arterial site of interest. The developed prototype system was validated on a cohort of 15 subjects (age $=43\pm 12$ years) that includes normotensives and hypertensives. Cs and CD measurements were obtained from the left carotid artery. A significant difference between carotid Cs and CD $(\Delta \mathrm{C})$ was observed in all recruited subjects (group average $\Delta \mathrm{C} = 0.92\pm 0.76\mathrm{m}/\mathrm{s})$, illustrating the arterial pressure dependency of local PWV. The absolute values of Cs and CD were within a range of 3.39 m/s to 7.5 m/s and 3.12 m/s to 5.82 m/s respectively. Normotensive versus hypertensive group-wise analysis was performed to investigate the degree of variation in the carotid local PWV over a cardiac cycle among different BP categories. Study results demonstrated that the proposed approach has a potential to provide valuable surrogate markers for cardiovascular risk assessment.

Large Variations in Pulse Wave Velocity and Reflection Patterns occur during a Hemodialysis Session and are not Related to the Degree of Ultrafiltration

Large Variations in Pulse Wave Velocity and Reflection Patterns occur during a Hemodialysis Session and are not Related to the Degree of Ultrafiltration

Reduction of cardiac pre-load has antithetical effects on blood pressure and arterial stiffness: Is blood pressure the main determinant of within-subject variation in pulse wave velocity?

ObjectiveBlood pressure (BP) is considered the most important determinant of within-subject variation in pulse wave velocity (PWV) and the possibility of altering arterial stiffness independently of BP is still a matter of debate. When investigating acute effects of a reduction in cardiac preload, we hypothesised that this would decrease BP and PWV.Design and methodsHypertensive patients (mean ± SD age 44 ± 14 years, n = 45) had brachial BP measurements (OMRON), central BP recorded by radial pulse wave analysis (SphygmoCor) and estimation of aortic PWV (aoPWV) by trans-thoracic echocardiography. Carotid-femoral PWV (cfPWV) was also evaluated by SphygmoCor in n = 17. Measurements were performed before and after (>5 minutes) supra-diastolic, sub-systolic pressure inflation of thigh cuffs in order to decrease venous return from the lower limbs. Evaluation of inferior vena cava (IVC) diameter was used to assess pre-load.ResultsLeg cuff-inflation was effective in reducing cardiac pre-load (change in IVC diameter (mean ± SE) from 1.6 ± 0.4cm to 1.3 ± 0.4cm, p < 0.01) and decreased both brachial and central SBP (−3 ± 0.9mmHg and −3.6 ± 1.2mmHg respectively, both p < 0.05) while change in DBP (0.8 ± 0.9mmHg) and heart rate (−0.1 ± 0.6 bpm) were not significant. By contrast, aoPWV increased by 0.8 ± 0.35m/s (p<0.01) and cfPWV by 1.05 ± 0.33 m/s (p = 0.014).ConclusionsContrary to our hypothesis, acute reduction of cardiac preload significantly decreased BP but had an opposite effect on PWV. This could be mediated by an increase in sympathetic tone triggered by reduction in circulating blood volume; sympathetic tone might affect PWV independently of BP.

Single-source PPG-based local pulse wave velocity measurement: a potential cuffless blood pressure estimation technique

Objective: A novel photoplethysmograph probe employing dual photodiodes excited using a single infrared light source was developed for local pulse wave velocity (PWV) measurement. The potential use of the proposed system in cuffless blood pressure (BP) techniques was demonstrated. Approach: Initial validation measurements were performed on a phantom using a reference method. Further, an in vivo study was carried out in 35 volunteers (age = 28 ± 4.5 years). The carotid local PWV, carotid to finger pulse transit time (PTTR) and pulse arrival time at the carotid artery (PATC) were simultaneously measured. Beat-by-beat variation of the local PWV due to BP changes was studied during post-exercise relaxation. The cuffless BP estimation accuracy of local PWV, PATC, and PTTR was investigated based on inter- and intra-subject models with best-case calibration. Main results: The accuracy of the proposed system, hardware inter-channel delay (<0.1 ms), repeatability (beat-to-beat variation = 4.15%–11.38%) and reproducibility of measurement (r = 0.96) were examined. For the phantom experiment, the measured PWV values did not differ by more than 0.74 m s−1 compared to the reference PWV. Better correlation was observed between brachial BP parameters versus local PWV (r = 0.74–0.78) compared to PTTR (|r| = 0.62–0.67) and PATC (|r| = 0.52–0.68). Cuffless BP estimation using local PWV was better than PTTR and PATC with population-specific models. More accurate estimates of arterial BP levels were achieved using local PWV via subject-specific models (root-mean-square error ⩽2.61 mmHg). Significance: A reliable system for cuffless BP measurement and local estimation of arterial wall properties.

A NEW SYSTEM FOR MEASUREMENT OF THE PULSE TRANSIT TIME, THE PULSE WAVE VELOCITY AND ITS ANALYSIS

Arterial stiffness is a strong determinant of cardiovascular risk. Pulse wave velocity (PWV) is an index of arterial stiffness, and its prognostic value has been repeatedly emphasized. The work presented in this paper is concerned with the design of a new system for measurement of the PWV and analysis. It is in fact related to the description of the hardware setup and the software development in order to measure and analyze the PWV. In the proposed system, the determination of the PWV is carried out through the measurement of the pulse wave transit time (PWTT) using the electrocardiogram (ECG) and the photoplethysmogram (PPG) and the distance separating the site of ejection of the systolic pulse and the site of measuring the PPG signal. The hardware setup therefore consists of an optical device to detect the PPG and electrodes to detect ECG, and different boards to process and digitalize these signals to be acquired in the PC and analyzed. The developed software is concerned with first, the acquisition and processing of both ECG and PPG signals then the determination of the PWV and finally its analysis for different subjects and conditions. The analysis of the PWV is carried out for subjects of different ages in different physiological conditions according to heart activity. The obtained results show that there is a high correlation ([Formula: see text]), between heart rate variability (HRV) and PWV. They also show that PWV increases with age. The analysis of the PWV variations with age is also carried out through different regression models. The obtained result shows that the cubic regression model best fits these variations.

Assessment of local pulse wave velocity distribution in mice using k-t BLAST PC-CMR with semi-automatic area segmentation

BackgroundLocal aortic pulse wave velocity (PWV) is a measure for vascular stiffness and has a predictive value for cardiovascular events. Ultra high field CMR scanners allow the quantification of local PWV in mice, however these systems are yet unable to monitor the distribution of local elasticities.MethodsIn the present study we provide a new accelerated method to quantify local aortic PWV in mice with phase-contrast cardiovascular magnetic resonance imaging (PC-CMR) at 17.6 T. Based on a k-t BLAST (Broad-use Linear Acquisition Speed-up Technique) undersampling scheme, total measurement time could be reduced by a factor of 6. The fast data acquisition enables to quantify the local PWV at several locations along the aortic blood vessel based on the evaluation of local temporal changes in blood flow and vessel cross sectional area. To speed up post processing and to eliminate operator bias, we introduce a new semi-automatic segmentation algorithm to quantify cross-sectional areas of the aortic vessel. The new methods were applied in 10 eight-month-old mice (4 C57BL/6J-mice and 6 ApoE (−/−)-mice) at 12 adjacent locations along the abdominal aorta.ResultsAccelerated data acquisition and semi-automatic post-processing delivered reliable measures for the local PWV, similiar to those obtained with full data sampling and manual segmentation. No statistically significant differences of the mean values could be detected for the different measurement approaches. Mean PWV values were elevated for the ApoE (−/−)-group compared to the C57BL/6J-group (3.5 ± 0.7 m/s vs. 2.2 ± 0.4 m/s, p < 0.01). A more heterogeneous PWV-distribution in the ApoE (−/−)-animals could be observed compared to the C57BL/6J-mice, representing the local character of lesion development in atherosclerosis.ConclusionIn the present work, we showed that k-t BLAST PC-MRI enables the measurement of the local PWV distribution in the mouse aorta. The semi-automatic segmentation method based on PC-CMR data allowed rapid determination of local PWV. The findings of this study demonstrate the ability of the proposed methods to non-invasively quantify the spatial variations in local PWV along the aorta of ApoE (−/−)-mice as a relevant model of atherosclerosis.

Clinical interaction between diabetes duration and aortic stiffness in type 2 diabetes mellitus

Diabetes complications increase with disease duration. No study was performed on the relationship between aortic stiffness and diabetes duration, taking into account the respective influence of such factors on macro- and microcirculation. In total, 618 subjects with type 2 diabetes (259 men) attending the Department of Internal Medicine of Tizi Ouzou Hospital (Algeria) were studied in collaboration with Hotel-Dieu Hospital (Paris, France). Brachial blood pressure (BP), anthropometric, clinical and biological data were evaluated. Aortic stiffness was estimated by carotid-femoral pulse wave velocity (PWV). From lower to higher tertile of diabetes duration, age, BP and PWV (10.1±2.7 to 12.3±2.8 m s-1) increased, while diabetes control and renal function worsened (all P<0.01). Diabetes duration was independently associated with PWV (R2=0.035, P<0.0001), even after adjustment for age, BP, heart rate, cardiovascular events and metabolic syndrome. Diabetes duration was significantly correlated to the prevalence of microalbuminuria (OR (95% CL) 1.3 (1.06-1.63), P=0.01), independently of age, sex, BP and renal function. Increased aortic stiffness was independently associated with the prevalence of cardiovascular events (P<0.001), reaching its maximal value above the first 2 years of diabetes duration. In conclusion, diabetes duration is an independent determinant of aortic stiffness in subjects with type 2 diabetes, representing about 4% of PWV variability. Diabetes duration is associated with microvascular complications independently of renal function, and with macrovascular complications through the presence of increased aortic stiffness.

SBP, DBP, and pulse blood pressure variability are temporally associated with the increase in pulse wave velocity in a model of aortic stiffness.

Enhanced aortic stiffness and blood pressure variability (BPV) are independent risk factors for cardiovascular disease and all-cause mortality in man. They are also correlated with increased blood pressure (BP) and/or arterial remodeling. However, the interplay between BP and BPV on the stiffening process is still unclear. Our objectives were to determine the temporal evolution of both BPV and pulse wave velocity (PWV), a surrogate measure of arterial stiffness, using an animal model of remodeling-dependent aortic stiffening. We thus, developed a new telemetric technique allowing continuous measurement of PWV in conscious, unrestrained rats. Studies were performed in spontaneously hypertensive rats (SHR) treated for 2 weeks with N-nitro-L-arginine methyl ester, a nitric oxide synthase inhibitor (SHR-LN). BPV was evaluated conventionally or with a new device composed of two pressure transducers in two different sets of rats. This allowed a continuous monitoring of telemetered PWV, systolic (SPV), diastolic (DPV), and pulse pressure variability (PPV). Aortic structure was then characterized by immunohistochemical analysis. SPV, DPV, and PPV were increased in SHR-LN, when calculated by 24-h SD or using average real variability a parameter used to assess short-term variability in man. We observed rapid and simultaneous increases in BP, SPV, and PWV. Interestingly, PPV was the most increased parameter resulting mainly from different time course of SPV and DPV. Structural alterations of the aortic wall were observed, with a eutrophic inward remodeling and accumulation of fibronectin and its two main receptors (α5 and αv integrins). This offers unequivocal evidence of a significant relationship between PWV, BPV, and arterial structure.

Circulating resistin concentrations are independently associated with aortic pulse wave velocity in a community sample.

The role of the adipokine, resistin in mediating increases in aortic stiffness is uncertain. We aimed to determine independent relations between circulating resistin concentrations and aortic pulse wave velocity (PWV) and wave reflection in a community-based sample with a high prevalence of untreated hypertension and obesity. Plasma resistin, adiponectin, and C-reactive protein concentrations (ELISA); carotid-femoral (aortic) PWV and the aortic reflected wave index (applanation tonometry and SphygmoCor software) were determined in 683 randomly selected participants of African ancestry from SOWETO, South Africa who had never received antihypertensive therapy. Resistin concentrations were not independently associated with office or 24-h (n = 492) blood pressure (BP). In a stepwise regression model with BMI included in the model, age (P < 0.0001), mean arterial pressure (P < 0.0001), plasma resistin concentrations (P < 0.005), female sex (P = 0.01), and creatinine concentrations (P < 0.01) contributed independently to variations in PWV. Independent relations between resistin concentrations and PWV persisted with further adjustments for C-reactive protein concentrations (P < 0.005), and the homeostasis model of insulin resistance (P < 0.02). Similar relations were noted with waist circumference rather than BMI in the model. Resistin concentrations were not independently associated with aortic reflected wave index or aortic BP. Resistin is independently and directly associated with aortic stiffness and these effects occur beyond BP, insulin resistance, and general inflammation.

High frame rate and high line density ultrasound imaging for local pulse wave velocity estimation using motion matching: A feasibility study on vessel phantoms

Pulse wave imaging (PWI) is an ultrasound-based method to visualize the propagation of pulse wave and to quantitatively estimate regional pulse wave velocity (PWV) of the arteries within the imaging field of view (FOV). To guarantee the reliability of PWV measurement, high frame rate imaging is required, which can be achieved by reducing the line density of ultrasound imaging or transmitting plane wave at the expense of spatial resolution and/or signal-to-noise ratio (SNR). In this study, a composite, full-view imaging method using motion matching was proposed with both high temporal and spatial resolution. Ultrasound radiofrequency (RF) data of 4 sub-sectors, each with 34 beams, including a common beam, were acquired successively to achieve a frame rate of ∼507Hz at an imaging depth of 35mm. The acceleration profiles of the vessel wall estimated from the common beam were used to reconstruct the full-view (38-mm width, 128-beam) image sequence. The feasibility of mapping local PWV variation along the artery using PWI technique was preliminarily validated on both homogeneous and inhomogeneous polyvinyl alcohol (PVA) cryogel vessel phantoms. Regional PWVs for the three homogeneous phantoms measured by the proposed method were in accordance with the sparse imaging method (38-mm width, 32-beam) and plane wave imaging method. Local PWV was estimated using the above-mentioned three methods on 3 inhomogeneous phantoms, and good agreement was obtained in both the softer (1.91±0.24m/s, 1.97±0.27m/s and 1.78±0.28m/s) and the stiffer region (4.17±0.46m/s, 3.99±0.53m/s and 4.27±0.49m/s) of the phantoms. In addition to the improved spatial resolution, higher precision of local PWV estimation in low SNR circumstances was also obtained by the proposed method as compared with the sparse imaging method. The proposed method might be helpful in disease detections through mapping the local PWV of the vascular wall.

The Effects of Hemodynamic Changes on Pulse Wave Velocity in Cardiothoracic Surgical Patients.

The effect of blood pressure on pulse wave velocity (PWV) is well established. However, PWV variability with acute hemodynamic changes has not been examined in the clinical setting. The aim of the present study is to investigate the effect of hemodynamic changes on PWV in patients who undergo cardiothoracic surgery. Using data from 25 patients, we determined blood pressure (BP), heart rate (HR), and the left ventricular outflow tract (LVOT) velocity-time integral. By superimposing the radial arterial waveform on the continuous wave Doppler waveform of the LVOT, obtained by transesophageal echo, we were able to determine pulse transit time and to calculate PWV, stroke volume (SV), cardiac output (CO), and systemic vascular resistance (SVR). Increases in BP, HR, and SVR were associated with higher values for PWV. In contrast increases in SV were associated with decreases in PWV. Changes in CO were not significantly associated with PWV.

Phlebotomy decreases arterial stiffness and endothelial dysfunction in patients with hereditary hemochromatosis

Hereditary Hemochromatosis (HH) is a genetically determined disease of iron overload with excessive tissue storage, which can lead to tissue injury, fibrosis and organ failure. Recently, an increase of cardiovascular risk (CVR) has been reported in this group. Pulse wave velocity (PWV) is the simplest way to assess arterial stiffness (AS), and has predictive value for CVevents. PWV variation preand postinduced ischemia of brachial artery has been validated to evaluate endothelial dysfunction (ED). We previously reported a significant enhanced PWV and endothelial dysfunction in 30 HH patients compared with healthy controls. Patients with HH treated with repetitive phlebotomies (standard of care for these patients) show significantly longer survival rate (5-10 years) than untreated patients. We hypothesized that phlebotomy reduces iron overload and decreases the excessive storage of this metal in the arterial wall, reducing the vascular stiffness and therefore decreasing carotid-femoral PWV. To test this hypothesis we measured carotid-femoral PWV before and after phlebotomy in HH patients to assess AS and carotid-braquial PWV variation pre and post induced ischemia to assess ED. We compared these results against matching controls. PWV and PWV variation were assessed using Complior System (Artech-Medical, Francia). Carotid-femoral PWV was significantly increased in HH patients compared to control group (8.5 1.7 m/s vs 6.4 0.8 m/s, P<0.001, n1⁄422/30 patients/ group). Change in braquial PWVafter transient ischemiawas reduced in HH patients (0.3%) compared to controls (8.2%) (P<0.001). Phlebotomy significantly reduced carotid-femoral PWV (Post-phlebotomy: 6.5 0.8 m/s vs pre-plebotomy: 8.5 1.7 m/s, P<0.00001) back to control values (6.4 0.8 m/s). Change in braquial PWV was parcially rescued after phlebotomy (0.7 14% vs 2.4 8.7%). These results showed a significant reduction in AS and a partial rescue of ED in HH patients post-phlebotomy, suggesting that the arterial wall may represent a novel target in HH treatment endpoint organs. Our findings may support features research including more patients with HH and others iron overload disorders.

Association of apolipoprotein B, LDL-C and vascular stiffness in adolescents with type 1 diabetes.

LDL cholesterol (LDL-C) is the current lipid standard for cardiovascular disease (CVD)-risk assessment in type 1 diabetes. Apolipoprotein B (apoB) may be helpful to further stratify CVD risk. We explored the association between apoB and pulse wave velocity (PWV) to determine if apoB would improve CVD-risk stratification, especially in type 1 diabetes adolescents with borderline LDL-C (100-129mg/dL). We hypothesized that type 1 diabetes adolescents with borderline LDL-C and elevated apoB (≥90mg/dL) would have increased PWV compared to those with borderline LDL-C and normal apoB (<90mg/dL), and that apoB would explain more of the variability of PWV than alternative lipid indices. Fasting lipids, including apoB, were collected in 267 adolescents, age 12-19years, with diabetes duration >5years and HbA1c 8.9±1.6%. Triglyceride to HDL-C ratio (TG/HDL-C) and nonHDL-cholesterol (nonHDL-C) were calculated. PWV was measured in the carotid-femoral segment. ApoB, nonHDL-C and TG/HDL-C correlated with PWV (p<0.0001). ApoB, nonHDL-C and TG/HDL-C remained significantly associated with PWV in fully adjusted models. In adolescents with borderline LDL-C (n=61), PWV was significantly higher in those with elevated apoB than in those with normal apoB (5.6±0.6 vs. 5.2±0.6m/s, p<0.01) and also remained significant after adjustment for CVD-risk factors (p=0.0002). Moreover, in those with borderline LDL-C, apoB explained more of the variability of PWV than nonHDL-C and TG/HDL-C. Elevated apoB is associated with increased arterial stiffness in type 1 diabetes adolescents. Measurement of apoB in addition to LDL-C may be helpful in stratifying CVD risk in type 1 diabetes adolescents, especially in those with borderline LDL-C.

Abstract 545: Modification Over Time of Pulse Wave Velocity Parallel to Changes in Both Office and 24h-ambulatory Peripheral BP as well as Aortic BP

Aim: to assess the relationship of changes in pulse wave velocity (PWV), a marker of target organ damage, with the variation in BP over time, as assessed by three different methods of measurement: office and 24h-ambulatory peripheral BP as well as aortic BP. Methods: Observational prospective study in hypertensive subjects with impaired glucose metabolism consecutively recruited from Spanish Hypertension Units. Aortic BP and carotid-femoral PWV were evaluated by radial applanation tonometry (Sphygmocor®) at baseline ( b ) and after 12 months of follow-up ( fu ). Peripheral BP measurements were also recorded at baseline and at 12 months follow-up: office BP was obtained as the average of triplicate measurements taken at 1 min-intervals after 5 min of seated rest, using validated oscillometric devices; 24h-ambulatory BP recordings were taken with a validated device (Spacelabs®-90207) at 20-minute intervals throughout both the self-reported awake and asleep periods. Clinical and anthropometric features were also recorded. PWV variation (Δ) over time was calculated as follows: Δ PWV= [(PWV fu - PWV b ) / PWV b ] x 100. BP variation over time was calculated with the same formula applied to BP values obtained with the different measurement techniques. Correlations (Spearman “Rho”) of Δ PWV and Δ BP were calculated. Results: n=209 patients; mean age: 61.8 ± 11.2 y; 39% (81 of 209) were female; 80% (167 of 209) had type 2 diabetes. Other risk factors: hypertension: 100%; dyslipidemia: 69% (144 of 209); smokers: 13% (28 of 209); body mass index: 30.9 ± 4.4 Kg/m 2 . Baseline office systolic/diastolic BP (mmHg): oSBP = 143 ± 20; oDBP = 82 ± 12. Follow-up office systolic/diastolic BP (mmHg): oSBP = 136 ± 20; oDBP = 79 ± 12. Baseline PWV: 10.01 ± 3.5 m/s. Follow-up PWV: 10.19 ± 3.21 m/s. Δ PWV correlated with: Δ oSBP (Rho=0.212; p=0.002), Δ 24h-SBP (Rho=0.254; p&lt;0.001), Δ daytime-BP (Rho=0.232; p=0.001), Δ nighttime-BP (Rho=0.320; p&lt;0.001) and Δ aortic-SBP (Rho=0.320; p&lt;0.001). Conclusion: Modification over time of PWV, a marker of target organ damage, parallel to changes in systolic BP, both office and 24h-ambulatory peripheral BP variation as well as aortic BP variation, at 12 months of follow-up. Among them, aortic SBP and nighttime peripheral SBP both showed the best correlation.

Serum free thyroxine levels are positively associated with arterial stiffness in the SardiNIA study.

Thyroid dysfunction may accelerate atherosclerosis. Aortic pulse wave velocity (PWV) is an early index of arterial stiffness and an important risk factor for cardiovascular disease and might therefore be linked to changes in thyroid activity. We investigated the relationship between thyroid function and carotid-femoral PWV, as an index of arterial stiffness. Cross-sectional cohort study. Participants from the SardiNIA study. Those being treated for thyroid diseases were excluded, yielding a sample of 5875 aged 14-102. Clinical parameters, blood tests including serum TSH and serum FT4, and carotid-femoral PWV were measured. After adjusting for confounders, a direct and linear association between FT4 and PWV was shown (multiple regression analysis). The model containing age, mean blood pressure, body mass index, heart rate, FT4, hypertension, diabetes and dyslipidaemia accounted for 55% of the variation in PWV. Like several other known risk factors, serum FT4 levels are associated with carotid-femoral PWV, suggesting that high FT4 levels have a detrimental effect on aortic stiffness and may contribute to ageing process of the vascular system. This finding may help to understand the pathogenesis of cardiovascular disease and contribute to improve prevention therapy.

Regional variations in the relationship between arterial stiffness and adipocyte volume or number in obese subjects.

Cardiovascular disease is associated with multiple risk factors including stiff arteries and large adipocytes. Whether the latter two are interrelated is unknown. We aimed to determine whether arterial stiffness is associated with fat cell size and number in subcutaneous or visceral white adipose tissue (WAT). A cross-sectional study of 120 obese subjects scheduled for bariatric surgery in whom WAT mass and distribution was assessed by dual-X-ray absorptiometry. Biopsies from visceral (greater omentum) and subcutaneous (abdominal) WAT were obtained to calculate fat cell volume and number. Arterial stiffness was determined as aortic pulse wave velocity (PWV). Visceral adipocyte volume, but not number, was strongly (P<0.0001) and positively correlated with PWV, explaining 20% of the inter-individual variations in this parameter. This relationship remained significant after correction for clinical confounders. PWV correlated positively (r=0.38, P<0.0001) with visceral (but not subcutaneous) WAT mass. Furthermore, PWV was also positively associated with subcutaneous adipocyte volume (r=0.20, P=0.031) and negatively with fat cell number (r=-0.26, P=0.006). However, the relationships between PWV and visceral WAT mass or subcutaneous fat cell size/number became non-significant when controlling for visceral fat cell volume. In a multiple regression analysis to determine the factors that explain variations in PWV, only visceral fat cell volume, age, pulse rate and diastolic blood pressure entered the model, together explaining 42% of the variation in PWV. Visceral fat cell volume was the only WAT parameter that constituted an independent and significant, positive regressor for arterial stiffness determined by PWV. Although a causal relationship is not established, visceral fat cell volume may explain the well-known correlation between central fat mass, arterial stiffness and cardiovascular risk, at least in severely/morbidly obese subjects.

24-h ambulatory pulse wave velocity and central blood pressure in type 2 diabetes

BackgroundPulse wave analysis from a brachial cuff permits ambulatory measurements of pulse wave velocity (PWV) and central blood pressure parameters. The diurnal variation of PWV in type 2 diabetes is unknown. MethodsWe evaluated the Arteriograph24 which is a brachial cuff based equipment for estimating PWV and central blood pressure data without the use of a transfer function, in 22 type 2 diabetic patients, who had two 24 h measurements performed. ResultsThe mean number of valid day time and nighttime measurements were 29 (range 16–50) and 18 (11–25), respectively. 21 patients had at least one qualifying report. Nighttime PWV was significantly lower than during the day (9.1 vs. 9.7 ± 0.8 mm/s, p < 0.01). Systolic aortic blood pressure was 6 mmHg lower than brachial blood pressure in the day time (p < 0.01) and 4 mmHg lower during the night (p < 0.05). Each single measurement was standardized with the 24 h average as reference thus generating data from 1004 paired observations. The standardized PWV correlated with standardized values of heart rate (r = 0.24, p < 0.001) and systolic aorta blood pressure (r = 0.20, p < 0.001). A stepwise multiple regression model with standardized pulse wave velocity as dependent variable included standardized heart rate, systolic aorta blood pressure and a dummy variable for day/night status (R2 = 0.091, p < 0.001). ConclusionThe Arteriograph24 is applicable for research purpose. PVW in type 2 diabetes is modestly reduced during the night. The intraindividual variation of heart rate contributed independently to the variation of PWV.

Determinants of arterial stiffness in female patients with Takayasu arteritis.

The assessment of pulse wave velocity (PWV) in Takayasu arteritis (TA) is complex because of many confounding factors. We evaluated PWV in female patients with TA and controls with comparable anthropometric and clinical variables and assessed a possible association of TA with disease variables. We evaluated 27 patients with TA consecutively. Exclusion criteria were menopause, smoking, diabetes, renal insufficiency, poorly controlled hypertension, cardiac arrhythmias, obesity, inflammatory comorbidities, pregnancy, and surgical procedures involving the aorta. Disease activity was determined by clinical and laboratory variables. As healthy controls, 27 subjects with comparable age, blood pressure, height, and weight were selected. Carotid-femoral PWV measurements were obtained using the Complior system. The mean PWV in patients with TA was higher than in healthy controls (9.77 ± 3.49 vs 7.83 ± 1.06 m/s; p = 0.009). Despite our strict selection criteria, patients with TA had an average systolic blood pressure (SBP) 8 mmHg higher than controls (p = NS), and significantly higher pulse pressure values. The multivariate linear regression model shows that 93.8% of the PWV variability is explained by the variables age, mean BP, and the disease itself (adjusted R(2) = 0.938). Stepwise logistic analysis using the PWV cutoff value established by the receiver-operator characteristic curve (> 8.34 m/s) as dependent variable, and measures with significance in univariate analysis as independent variables revealed that TA (OR 4.69; 95% CI 1.31-16.72; p = 0.017) and mean BP (OR 1.06; 95% CI 1.00-1.12; p = 0.048) were independently associated with higher PWV. Further analysis of disease variables revealed that PWV values were not correlated with erythrocyte sedimentation rate, C-reactive protein, cumulative dose of glucocorticoid, or ejection fraction (p > 0.05). In our cohort of female patients with TA, the disease itself and mean BP were the strongest determinants associated with arterial stiffness.

Exaggerated blood pressure response and arterial stiffness

Exaggerated blood pressure response (EBPR) to exercise stress test is often present in hypertensive patients but the clinical significance in normotensive subjects is unclear and poorly studied. We consider that this group may advance to future cardiovascular (CV) complications such as hypertensive crises and target organ damage for no development of vascular buffer mechanism. Pulse wave velocity (PWV) is nowadays the gold standard and the simplest way to asses arterial stiffness (AS) and has been used as a predictive value of aortic stiffness for cardiovascular events. PWV variation pre and post induced ischemia of brachial artery has been validated for evaluate endothelial dysfunction (ED). The purpose of this study was to examine AS and ED in normotensive subjects with EBPR on a graded treadmill test and compared with healthy people free of CV disease, with normal blood pressure response. We tested 40 normotensive patients (51.4 16.4 years old, 15 males) with EBPR to exercise test and 25 controls. Exercise was performed on a treadmill. For AS we used carotid-femoral PWV (Complior System , Artech, France), and PWV variation for ED. All patients were non smokers and were tested at the same morning times with 4 hours without foods or drinks, with 20 minutes previous rest. Baseline characteristics and biochemistry are shown on table 1. All the patients were studied with ambulatory blood pressure monitoring (ABPM) (Spacelabs Health care USA 90217A) for rule out masked hypertension. We observed a PWVof 8.7 1.8 m/s in EBPR and 7.0 0.9 m/s in control group (p<0,01) and a decrease of 8.2% in PWV post induced ischemia for control subjects versus a paradoxical response in EBPR group with an increase of 4.8% (p<0.001). No major determinants for AS (hypertension, old age, renal insufficiency and diabetes) reach statistical significance. We found AS enhanced and ED in EBPR group (structural and functional vascular impact) and could be, among others, one of the mechanism for increase CV risk in this group.

Abstract 412: Obesity is an Independent Predictor Of Arterial Stiffness

Background Arterial stiffness assessed by carotid-femoral pulse wave velocity (PWV) is an independent predictor of cardiovascular morbidity and mortality. We aimed to investigate how various measures of obesity affect arterial stiffness. Methods We conducted a population-based cross-sectional survey in 8,042 South Indians above the age of 20 years. Following completion of a detailed medical history questionnaire, all participants underwent haemodynamic screening including brachial and central blood pressure, and PWV measurements using a high-fidelity applanation tonometry. The study included anthropometric measurements and fasting blood for total cholesterol (TC), triglyceride (TG), high density lipoprotein (HDL), low density lipoprotein (LDL) and blood glucose (BG) levels. After the exclusion of people with previous history of diabetes, hypertension and dyslipidemia on drug therapy, 5,841 subjects (mean age 41.6 years; 58% women) constituted the study sample Results In an univariate analysis, PWV correlated positively with age, mean blood pressure (MAP), heart rate (HR), body mass index (BMI), waist circumference (WC), waist to hip ratio (WHR), body fat percent (BF%), TC, TG, LDL and BG levels (P &lt;0.001) and negatively with HDL levels (P=0.005). In a multivariate regression analysis, majority of the PWV variability in the model was accounted for by MAP and age, (cumulative adjusted R2 change of 32.79% as compared to the total adjusted R2 change of 35.25%). However, BMI (β= 0.042; adjusted R2 change=2.83%; p&lt;0.001) independently correlated with PWV and its contribution to the PWV variability was far more significant compared to LDL, BG and TG (cumulative adjusted R2 change=1.08%). Multivariate regression analysis using the WC, WHR, or BF% instead of the BMI continued to demonstrate a significant independent effect of obesity parameters on PWV. Conclusion: In a large a population-based cross-sectional survey the study demonstrates a positive, independent association between obesity parameters and increased arterial stiffness.