PWV Measurements Research Articles

Forty‐Eight‐Hour Ambulatory Blood Pressure and Carotid‐Femoral Pulse Wave Velocity in Hemodialysis Patients

Carotid-femoral pulse wave velocity (cfPWV) is an important predictor of cardiovascular events in the general population and also in hemodialysis (HD) patients. In the general population, cfPWV is strongly associated with age and blood pressure (BP). The best timing and method of BP measurement in HD patients is uncertain. Ambulatory blood pressure measurements (ABPM) have been used to better define the relationship between BP, target organ damage, and outcomes in HD patients. The aim of this study was to determine the possible association between cfPWV, cardiovascular risk factors, single BP measurements, and 48-hour ABPM in chronic HD patients. Thirty-three HD patients (22 men, 11 women) were included. After the end of the mid-week HD session, BP was measured, arterial stiffness was estimated by cfPWV, and 48-hour ABPM was performed. The mean systolic and diastolic BP readings before cfPWV measurement were 136/79 mmn Hg, and the mean 48-hour systolic and diastolic BP readings were 131/76 mm Hg. The mean and range of the cfPWV measurements were 8.31 ± 2.35 m/s and 5.18-16.53 m/s, respectively. Using regression analysis, no association between cfPWV and BP before PWV measurements was found. A statistically significant correlation between cfPWV and 48-hour systolic and diastolic ABPM was found. Using multiple regression analysis (including age, sex, smoking, diabetes, body mass index, total cholesterol, low- and high-density lipoprotein cholesterol, triglycerides, C-reactive protein, albumin, phosphorus, calcium, and iPTH) 48-hour systolic (P < 0.001) and diastolic ABPM (P < 0.005) still remain significantly associated with cfPWV. Only 48-hour ABPM was associated with cfPWV in HD patients in our study. We found no relationship between cfPWV and other cardiovascular risk factors.

PWV Measurement Influenced by Distance Between Two Recording Sites

PWV Measurement Influenced by Distance Between Two Recording Sites

Consistency of aortic distensibility and pulse wave velocity estimates with respect to the Bramwell-Hill theoretical model: a cardiovascular magnetic resonance study.

BackgroundArterial stiffness is considered as an independent predictor of cardiovascular mortality, and is increasingly used in clinical practice. This study aimed at evaluating the consistency of the automated estimation of regional and local aortic stiffness indices from cardiovascular magnetic resonance (CMR) data.ResultsForty-six healthy subjects underwent carotid-femoral pulse wave velocity measurements (CF_PWV) by applanation tonometry and CMR with steady-state free-precession and phase contrast acquisitions at the level of the aortic arch. These data were used for the automated evaluation of the aortic arch pulse wave velocity (Arch_PWV), and the ascending aorta distensibility (AA_Distc, AA_Distb), which were estimated from ascending aorta strain (AA_Strain) combined with either carotid or brachial pulse pressure. The local ascending aorta pulse wave velocity AA_PWVc and AA_PWVb were estimated respectively from these carotid and brachial derived distensibility indices according to the Bramwell-Hill theoretical model, and were compared with the Arch_PWV. In addition, a reproducibility analysis of AA_PWV measurement and its comparison with the standard CF_PWV was performed. Characterization according to the Bramwell-Hill equation resulted in good correlations between Arch_PWV and both local distensibility indices AA_Distc (r = 0.71, p < 0.001) and AA_Distb (r = 0.60, p < 0.001); and between Arch_PWV and both theoretical local indices AA_PWVc (r = 0.78, p < 0.001) and AA_PWVb (r = 0.78, p < 0.001). Furthermore, the Arch_PWV was well related to CF_PWV (r = 0.69, p < 0.001) and its estimation was highly reproducible (inter-operator variability: 7.1%).ConclusionsThe present work confirmed the consistency and robustness of the regional index Arch_PWV and the local indices AA_Distc and AA_Distb according to the theoretical model, as well as to the well established measurement of CF_PWV, demonstrating the relevance of the regional and local CMR indices.

Arterial functions: how to interpret the complex physiology

Arterial pressure is a cyclic phenomenon characterized by a pressure wave oscillating around the mean blood pressure, from diastolic to systolic blood pressure, defining the pulse pressure. Aortic input impedance is a measure of the opposition of the circulation to an oscillatory flow input (stroke volume generated by heart work). Aortic input impedance integrates factors opposing LV ejection, such as peripheral resistance, viscoelastic properties and dimensions of the large central arteries, and the intensity and timing of the pressure wave reflections, associated with the opposition to LV ejection influenced by inertial forces. The two most frequently used methods of arterial stiffness are measurement of PWV and central (aortic or common carotid artery) pulse wave analysis, recorded directly at the carotid artery or indirectly in the ascending aorta from radial artery pressure curve. The arterial system is heterogenous and characterized by the existence of a stiffness gradient with progressive stiffness increase (PWV) from ascending aorta and large elastic proximal arteries to the peripheral muscular conduit arteries. Analysis of aortic or carotid pressure waveform and amplitude concerns the effect of reflected waves on pressure shape and amplitude, estimated in absolute terms, augmented pressure in millimetre of mercury, or, in relative terms, 'augmentation index' (Aix in percentage of pulse pressure). Finally, if the aortic PWV has the highest predictive value for prognosis, the aortic or central artery pressure waveform should be recorded and analysed in parallel with the measure of PWV to allow a deeper analysis of arterial haemodynamics.

Potentials and Pitfalls of Local PWV Measurements

Potentials and Pitfalls of Local PWV Measurements

Response to "Potentials and Pitfalls of Local PWV Measurements"

Response to "Potentials and Pitfalls of Local PWV Measurements"

Validation and reproducibility of aortic pulse wave velocity as assessed with velocity‐encoded MRI

To validate magnetic resonance imaging (MRI) assessment of aortic pulse wave velocity (PWV(MRI)) with PWV determined from invasive intra-aortic pressure measurements (PWV(INV)) and to test the reproducibility of the measurement by MRI. PWV(MRI) was compared with PWV(INV) in 18 nonconsecutive patients scheduled for catheterization for suspected coronary artery disease. Reproducibility of PWV(MRI) was tested in 10 healthy volunteers who underwent repeated measurement of PWV(MRI) at a single occasion. Velocity-encoded MRI was performed on all participants to assess PWV(MRI) in the total aorta (Ao(total)), the proximal aorta (Ao(prox)), and the distal aorta (Ao(dist)). The results are expressed as mean +/- SD, Pearson correlation coefficient (PCC), and intraclass correlation (ICC). Good agreement between PWV(MRI) and PWV(INV) was found for Ao(total) (6.5 +/- 1.1 m/s vs. 6.1 +/- 0.8 m/s; PCC = 0.53), Ao(prox) (6.5 +/- 1.3 m/s vs. 6.2 +/- 1.1 m/s; PCC = 0.69), and for Ao(dist) (6.9 +/- 1.1 m/s vs. 6.1 +/- 1.0 m/s; PCC = 0.71). Reproducibility of PWV(MRI) was high for Ao(total) (4.3 +/- 0.5 m/s vs. 4.6 +/- 0.7 m/s; ICC = 0.90, P < 0.01), Ao(prox) (4.3 +/- 0.9 m/s vs. 4.7 +/- 1.0 m/s; ICC = 0.87, P < 0.01), and Ao(dist) (4.3 +/- 0.6 m/s vs. 4.4 +/- 0.8 m/s; ICC = 0.92, P < 0.01). MRI assessment of aortic pulse wave velocity shows good agreement with invasive pressure measurements and can be determined with high reproducibility.

Blood Pressure Response Under Chronic Antihypertensive Drug Therapy: The Role of Aortic Stiffness in the REASON (Preterax in Regression of Arterial Stiffness in a Controlled Double-Blind) Study

We sought to evaluate the role of arterial stiffness on blood pressure (BP) response to drug treatment. Increased arterial stiffness (pulse wave velocity [PWV]) is associated with increased systolic blood pressure (SBP). Antihypertensive drug therapy achieves better control of diastolic blood pressure (DBP) than SBP does, implying that increased PWV might be a predictor of the SBP response to treatment. The REASON (Preterax in Regression of Arterial Stiffness in a Controlled Double-Blind) study is a randomized, double-blind trial comparing atenolol versus perindopril/indapamide; 375 patients with hypertension, with BP and PWV measurements at baseline and after 12 months of treatment, were divided into 3 tertiles according to baseline PWV and included in a post-hoc analysis. After 12 months of treatment, BP differed significantly between PWV tertiles (the third having the lowest response, p < 0.05). Factors related to smaller BP decline were low baseline BP, high baseline PWV, need for a double dose of treatment, use of atenolol (only for SBP response), and age (only for DBP). Although DBP control did not differ in the PWV tertiles, SBP control was significantly associated with PWV level (p = 0.001) as well as with the use of perindopril/indapamide (p < 0.001). The predictive value of PWV on BP response was independent of age, sex, mean BP, and cardiovascular risk factors. Baseline PWV is a significant predictor of BP response to antihypertensive treatment, independent from age, the need for increasing drug dosage, and the presence of cardiovascular risk factors. Achievement of SBP control appears to be influenced by aortic stiffness as well as by angiotensin-converting enzyme inhibition.

Determining pulse wave velocity using MRI: a comparison and repeatability of results using seven transit time algorithms

Introduction •Magnetic resonance imaging (MRI) provides a non-invasive method for assessing segmental aortic pulse wave velocity (aPWV). •However, the best mathematical algorithm for transit time calculation using MRI flow waves is unclear. Methods • 7 different algorithms were applied to aortic flow waveforms measured by MRI • 10 subjects, 36±7 years, 4 male • Two measurements were recorded in each subject on different days for repeatability analysis. • PWV was calculated between 5 sites along the aorta (total 80 PWV measurements). • A statistically extreme outlier result of PWV (> 3 × interquartile range) was classed as a “failed” measurement and the success rate across the 80 samples calculated. 0.0 0.2 0.4 0.6 0.8 1.0 0 100 200 300 400

Determinants of 1-Year Changes of Brachial Ankle Pulse Wave Velocity (baPWV) in Patients with Type 2 Diabetes Mellitus

Background: Cardiovascular disease is the leading cause of mortality in ty pe 2 diabetes. PWV correlates well with arterial distensibility and stiffness and a useful approach for evaluating the severity of systemic atherosclerosis in adults, and, in particular, the measurement of brachial-ankle PWV (baPWV) has been commonly reported as a simple, noninvasive and practicable method. baPWV was mainly affected by age, SBP and sex. And also, baPWV was affected by many different fac tors such as body weight, BMI, waist to hip ratio, HbA1c, microalbuminuria, triglyceride, ϒGTP, duration of DM. We evaluated determinants of 1-year changes of baPWV in patients with type 2 DM. Methods: The study group comprised 189 diabetic patients who measured ankle brachial pressure index (ABI), baPWV at base line and 1-year later. The anthropometric parameters, blood pressure, pulse pressure, fasting plasma glucose (FBS), fasting insulin, A1c, lipid profile, hsCRP, microalbuminuria, AST/ALT, ϒGTP were also checked concurrently. We also analyzed correlation be tween change of baPWV and subject's medications. We retrospectively analyzed the relationship betwe en the 1-year changes of baPWV and the other factors. All analyses were performed with the SPSS Version 14.0 and P values < 0.05 were considered significant. Results: baPWV change was affected by systolic blood pressure change, diastolic blood pressure change, pulse pressure change, body weight, BMI, triglyceride change, insulin treatment and total cholesterol. Multiple regression analysis of the relationship between change of baPWV and other associated variables shows that the 1-year change of baPWV was significantly associa ted with the changes of blood pressure and insulin treatment in patients with type 2 DM. Conclusion: 1-year change of baPWV was significantly associated with the changes of blood pressure in patients with type 2 DM. (KOREAN DIABETES J 32:346-357, 2008)

How to assess arterial compliance in humans

How to assess arterial compliance in humans

Coronary artery calcification and aortic pulse wave velocity in chronic kidney disease patients

Patients with end-stage renal disease (ESRD) are at increased risk of cardiovascular mortality and morbidity. Many complications arise in ESRD patients as a result of the twin arterial pathologies of atherosclerosis and arteriosclerosis. Part of this latter process is calcification of the arterial media, which is thought significantly to increase vascular stiffness. The aim of our study was to explore the relationship between measures of arterial stiffness-pulse wave velocity (PWV)-and the extent of calcification in the coronary arteries (CAC). Over a period of 2 years 82 patients from our renal unit were invited to participate in our study. Sixty-two patients agreed to undergo electron beam computerized tomography (EBCT), and in 55 (38 males and 17 females), PWV measurements were made. EBCT and PWV measurements were done according to previously described protocols. The mean age of the 55 patients was 56.4 years. The mean duration of dialysis was 65.4 months, and the mean CAC score was 2551. The mean PWV was 9.13 m/s. PWV strongly correlated with total CAC even after correction for age, dialysis duration, and time averaged C-reactive protein (CRP) (P= 0.0001). CAC scores were significantly different when compared according to PWV tertiles (P= 0.0001). We have demonstrated that PWV is strongly related to the degree of EBCT-derived coronary artery calcium score in chronic kidney disease patients.

512 Prevalence of hypertension and left ventricular hypertrophy in a Romanian population. A populational clinical — echocardiographic study

with a relative wall thickness >0.45; global diastolic dysfunction (GDD), detected by correcting for age the TD flow early to atrial (E/A) ratio values; regional diastolic dysfunction (RDD) evaluated by TDI, with the sample volume positioned within the basal septum and defined according to the age-corrected tissue E/A ratio values. CR was found in 12 patients (70%); among these, 4 showed both GDD and RDD, while 5 patients showed only RDD. In the absence of CR, no patient showed either GDD or RDD. At Fisher test analysis, RDD was significantly associated with the presence of CR (p=0.019), whereas no significant association was found between CR and GDD. TDI showed a higher sensitivity in detecting diastolic dysfunction than TD (75% vs 33%) and a higher negative predictive value (63% vs 38%); both TDI and TD had a specificity and positive predictive value of 100%. In conclusion, in hypertensive patients with cardiac remodeling an abnormal re- gional diastolic function can be observed more frequently than a global diastolic dysfunction, thus suggesting that TDI is able to detect early impairment of diastolic function more accurately than pulsed transmitralic Doppler even in the absence of cardiac hypertrophy. 511 Arterial distensibility and ambulatory blood pressure as determinant of left ventricular hypertrophy and intima-media thickeness in elderly subjects. Morbidity and mortality in hypertension are primary related to arterial damages that may affect several organs.The aim of this study was to evaluate the am- bulatory blood pressure measurement (ABPM) and pulse wave velocity analysis (PWV) in 3 groups composed by elderly subjects, being selected as normoten- sive (Group I, n=24,72,04±6,02years); isolated systolic hipertensive (Group II, n=32, 72,34±4,55years); and systolic-diastolic hipertensive (Group III, n=33, 71,42±5,72years), in an effort to identify, among the assessed variables, those that could be correlated to the determination of the target organ damage (TOD) defined as left ventricular hypertrophy (LVH) and intima-media thickness of the left and/or right common carotid artery (IMT-CCA).The variables analyzed involved: the ABPM measures; the IMT-CCA measures, by means of carotid ultrasonography; the left ventricular mass and left ventricular mass index measures, by means of echocar- diography; and the PWV measures. The distribution of age, gender and anthropo- metrical rates showed similarity among the 3 groups, the same occurring to the analysis of the averages of the biochemical parameters. We also demonstrated a similar distribution for IMT-CCA in the 3 assessed groups (p=0,200), and for LVH in the 2 hypertensive groups (p=0,557), the latest showing, however, higher statistical values when compared to the normotensive group (p<0,001). The variables with positive correlation to the LVM were: 24hour systolic, diastolic and pulse pressure; daytime systolic BP; night-time systolic and diastolic BP and PWV; and the variable with negative correlation was the systolic-nocturnal fall. The 24h systolic BP and pulse pressure, daytime systolic and diastolic BP and PWV figured as positive correlates to the IMT-CCA, while the systolic-nocturnal fall and diastolic-nocturnal fall appeared as negative correlations for IMT-CCA. By investigating the TOD determinants, we veryfied that the 24h systolic BP was the only variable associated to the LVH (p=0,0161), while the PWV was the only associated to the IMT-CCA (p=0,033). Thus, we demonstrated that the analysis of these ABP and PWV variables is a resource of great validity for the investigation of the target organ in elderly subjects. ± 0.31, p<0.001). LV mass was significantly higher in group A (202.3 ± 53.5 g vs 177.4 ± 51 g, p<0.001). Using the Levy height-indexed threshold (143 g/m for men and 102 g/m for women), LVH prevalence was 36% in the hypertensive group. Systolic blood pressure (BP) in group A was 166.2 ± 20 mm Hg, diastolic BP was 93.2 ± 12.2 mm Hg, and the proportion of treated hypertensive pts with normal BP values was of only 15%, reflecting poor BP control. Conclusions: The prevalence of HTN in this population is high, as is the preva- lence of LVH. BP control in treated pts with known HTN is poor. These findings have important medical and economic implications and should represent the ba- sis for setting-up more efficient programmes for a better BP control in the general population.

Piezoelectric sensor determination of arterial pulse wave velocity

Arterial pulse wave velocity (APWV) is a measure of the elasticity (or stiffness) of peripheral arterial blood vessels. The pulse referred to here will be the pressure pulse as opposed to the flow pulse measured by ultrasound Doppler. The pressure pulse velocity varies over the range from about 12 m s−1 to 15 m s−1 in stiff peripheral arteries, whereas in normal arteries it has a velocity in the range of 7 to 9 m s−1.The aim of this project was the development of a fast and easy to use system for the determination of peripheral arterial pulse wave velocity. The principle of the PWV measurement is based on simultaneous measurement of two pulse waves at two different positions, such as the radial artery at the wrist and the brachial artery just above the elbow. By determining the pulse transit time between these points and the distance measured between the two locations, pulse wave velocity may then be calculated. The pressure pulse detection is done by using two piezoelectric sensors which generate a measurable voltage at the output contacts if they are mechanically deformed. The deformation produced voltage is first amplified and filtered and then digitalized with a data acquisition card. The analysis of the data obtained from the sensors includes a filtering process, the calculation of the PWV with three different methods—foot-to-foot, cross-correlation and peak-to-peak—and the determination of the arterial pulse rate.Extensive measurements with human test subjects were carried out to optimize the techniques of data acquisition and analysis. For example, it was found that the best procedure was to hold the sensors in place using elastic straps alone. The data analysis was upgraded with an additional software module, which deletes, in effect, outriders or invalid measurements. With the optimized system, a series involving eight test subjects ranging in age from 22 to 32 years was completed (all normotensive). The arterial pulse wave velocities determined covered a range from 6 m s−1 to 12 m s−1, with an average standard deviation of less than 2.5 m s−1 for individual results. These are slightly higher, but close to published APWV data. The results showed that reproducible results can be obtained with the existing PWV acquirement and analysis system.

PWV Measurement of Persons Undergoing Checkups at Human Dry Dock

PWV Measurement of Persons Undergoing Checkups at Human Dry Dock

Accuracy of Multi-Element Tonometry Sensor-Based Noninvasive PWV Measurement System as Evaluated in Animal Model

Accuracy of Multi-Element Tonometry Sensor-Based Noninvasive PWV Measurement System as Evaluated in Animal Model

In vivo determinants of arterial biophysical properties: methodological considerations: (Reply to Lehmann and Gosling)

Dear Sir,We do not believe that there is much value in continuing a correspondence now only vaguely related to a study published more than 2 years ago [1]. The report in question was a cross sectional study of a large group of ethnic Chinese subjects in whom ultrasound of the aorta with conventional cardiac echocardiographic equipment and pulse wave velocity were used to examine arterial properties. No interventions took place or were planned subsequent to the initial investigation. We prefer to rely on conventional peer review rather than publish findings in letters and commentaries not generally subject to such evaluation. There are, however, two points we wish to make on this occassion. Firstly to correct the impression that the use of conventional echocardiography equipment and transthoracic techniques to assess the stiffness of the proximal aorta is a technical approach limited to ourselves. It has been used in a number of peer reviewed articles from other groups [2–9]and we refer interested readers to these for further information, including data on measurement variability. It also appears that our recent comments on the use of pulse wave velocity [10]have been somewhat misconstrued. We did not criticise this technique but stressed that it was one of a number of techniques available and stated `that techniques are available which, in specific cases, may be more pathophysiologically relevant than measurement of PWV'. We still believe this to be the case.

Electrical simulation of arterial pulse waves--an aid to continuous pulse wave velocity measurements.

The purpose of the simulator is to serve as a substitute for human subjects while developing and testing equipment measuring PWV continuously over long periods of time. For this purpose the shape of the simulated pulse should have the geometrical properties of the arterial pulse wave essential for measuring foot to foot PWV. These properties were defined and realized by choosing an appropriate input function and a shaping network. It was proved, by calculations based on steady state analysis, using Laplace transforms, that the simulated arterial pulse wave has the defined geometrical properties. The dicrotic complex, which sometimes interferes with foot to foot PWV measurements, was added to the simulated pulse wave by a separate circuit.