Age-associated changes in regional aortic pulse wave velocity

OBJECTIVES: This study was designed to determine noninvasively the age-associated changes in regional mechanical properties in normals using phase-contrast magnetic resonance imaging (PCMRI). BACKGROUND: It has been well documented that there is a progressive increase in aortic pulse wave velocity (PWV) with age. Previously, PWV has been measured at a single aortic location, or has compared arterial waves between carotid and femoral points to determine PWV. METHODS: Applanation tonometry (TONO) and in-plane PCMR was performed in 24 volunteers (12 men) ranging in age from 21 to 72 years old. The PCMRI PWV was measured in three aortic segments. As validation, TONO was performed to determine PWV between the carotid and femoral artery. RESULTS: When PCMRI PWV was averaged over the three locations, it was not different from TONO (7.9 +/- 2.3 vs. 7.6 +/- 2.4 m/s, respectively). When the volunteers were divided into groups of < 55 and > or =55 years old, the younger group showed similar PWV at each aortic location. However, the older group displayed significantly increased PWV in the region spanning the ascending and proximal descending aorta compared with the mid-thoracic or abdominal segments (10.6 +/- 2.5 m/s, 9.2 +/- 2.8 m/s, and 7.1 +/- 1.7 m/s, respectively, p < 0.001, analysis of variance). CONCLUSIONS: In-plane PCMRI permits determination of PWV in multiple aortic locations in a single acquisition. Progressive fragmentation of elastic fibers and alterations in the regulation of vascular tone may result in an age-related, regional increase in PWV primarily affecting the proximal aorta.     

Risk factors of atherosclerosis and aortic pulse wave velocity

Aortic pulse wave velocity (PWV) is a noninvasive technique that can estimate aortic stiffness or organic change quantitatively. The authors examined the correlation between age and the PWV value in 113 subjects and also examined the relationship between atherosclerotic associated diseases and PWV. A positive correlation was observed between age and the PWV value. No significant difference was found in the PWV value between groups with and without risk factors of atherosclerosis. No significant difference was observed in the PWV value between groups with and without a history of atherosclerotic disease.     

Increased pulse wave velocity and shortened pulse wave propagation time in young patients with rheumatoid arthritis

BACKGROUND: Rheumatoid arthritis (RA) is a systemic immune and inflammatory disease associated with excess cardiovascular morbidity and mortality. Pulse wave velocity (PWV) is an index of arterial stiffness and a marker of cardiovascular events. OBJECTIVE: To investigate arterial stiffness using carotid-femoral (aortic) PWV measurements in young patients with RA. PATIENTS AND METHODS: Eight patients (aged 21 to 34 years, seven women, mean RA duration 13.8+/-12.6 months) with RA according to the criteria of the American College of Rheumatology, and eight age- and sex-matched control subjects (aged 22 to 34 years, seven women) were recruited. Aortic PWV was determined using an automatic device, the Complior (Complior Colson, France), which allowed on-line pulse wave recording and automatic calculation of PWV. RESULTS: The carotid-femoral PWV, systolic blood pressure and heart rate were higher in young patients with RA than in sex- and age-matched control subjects (P=0.03, P=0.02 and P=0.002, respectively). In the young patients with RA, pulse wave propagation time between measurement sites was significantly shorter than in the control group (P=0.02). There were no significant differences in the sex, age, body mass index, waist to hip ratio, diastolic blood pressure, mean blood pressure or pulse pressure between the two groups (P=1.00, P=0.71, P=0.20, P=0.66, P=0.55, P=0.07 and P=0.11, respectively). CONCLUSION: The carotid-femoral PWV is increased and pulse wave propagation time is decreased in young patients with RA. Measurements of carotid-femoral PWV may provide a simple and noninvasive technique for identifying patients at increased risk of vascular disease.     

Determination of aortic elastic modulus by pulse wave velocity and wall tracking in a rat model of aortic stiffness.

Several methods have been used to evaluate the elastic modulus of the aortic wall in the rat, but these have never been compared when used simultaneously. We measured thoracoabdominal pulse wave velocity (PWV) and changes in thoracic aorta diameter during the cardiac cycle (with wall echo-tracking) in pentobarbital-anesthetized adult male Wistar rats; half of the group had previously received vitamin D3 plus nicotine (VDN) in order to increase the stiffness of the aortic wall. The Moens-Korteweg elastic modulus (E(MK)) was calculated from PWV and the ratio of the internal diameter to the medial thickness determined by histomorphometry following in situ pressurized fixation. The incremental elastic modulus (E(inc)) was calculated from the distensibility coefficient and end-diastolic diameter measured by wall echo-tracking and the medial thickness determined by histomorphometry. Both values were higher in VDN rats than in controls: E(inc) 8.9 +/- 0.5 and 5.7 +/- 0.4.10(6) dyne/cm(2), p < 0.05; E(MK) 7.6 +/- 0.5 and 4.1 +/- 0.5.10(6) dyne/cm(2), p < 0.05. E(inc) was greater than E(MK) and this was partially due to the fact that the in vivo end-diastolic diameter measured by ultrasound was greater than the mean aortic diameter measured ex vivo by histomorphometry. In conclusion, different methods for the measurement of the elastic properties of the aortic wall gave similar results in controls and in a rat model of aortic stiffness.     

Reference values of aortic pulse wave velocity in the elderly

BACKGROUND: Increased aortic pulse wave velocity (AoPWV) is an independent predictor of cardiovascular morbidity and mortality. There are, however, no generally accepted limits for defining the normal or reference values. The aim of the present study was to define reference values for AoPWV. PATIENTS AND METHODS: AoPWV was assessed using applanation tonometry (PulsePen device) in a community living ambulatory population of 455 individuals aged 60-75 years. AoPWV was studied in a group of 206 individuals without hypertension or diabetes, called the 'reference-values group' (RVG), and in a group of 249 individuals with hypertension or diabetes, called the hypertension-diabetes group (HDG). The 95th percentile of the samples was used to determine the upper limit of AoPWV reference values. RESULTS: Mean AoPWV was 8.7+/-2.3 m/s in the RVG and 10.2+/-2.5 m/s in the hypertension-diabetes group (P<0.0001). In the RVG, median AoPWV in the three age subgroups was 8.0 m/s (7.6-8.5) in the 60-64-, 8.0 m/s (7.5-9.0) in the 65-69- and 9.0 m/s (7.9-9.5) in the 70-75-year-old group (NS among groups). In the entire RVG, the upper bounds of the 75th and the 95th percentile of the sample's AoPWV were 10 and 13 m/s, respectively, with no difference between sexes. CONCLUSION: In elderly individuals of 60-75 years, an AoPWV value below 10 m/s, measured with the PulsePen device, can be considered as a normal value. Values of 10-13 m/s can be considered as 'high normal' or 'borderline', whereas an AoPWV above 13 m/s is frankly elevated. This study provides, for the first time in the elderly, reference values of AoPWV.     

Measurement variation of aortic pulse wave velocity in the elderly

Accurate and reproducible measures are required to study arterial stiffness in human populations. The reproducibility of aortic pulse wave velocity was evaluated in 14 participants from a population-based study of cardiovascular disease in the elderly. Three data files were collected per participant by each of two sonographers and files were read by two readers. Seven of the 14 participants returned for a second visit 1 week later to assess between-visit variability. Reproducibility was evaluated with Pearson and intraclass correlations and by the absolute value of the difference between replicate values. The overall reliability coefficient was r_I = 0.77. Between-sonographer, between-reader, and between-visit correlations were r_P = 0.80 to 0.87, r_P = 0.73 to 0.89 and r_P = 0.63. The mean absolute value of the difference between replicates was 59.4 to 94.0 cm/sec and 88.7 to 112.8 cm/sec for sonographers and readers, respectively. These results indicate that the mean PWV measure is reproducible even when sonographers and readers are newly trained.     

Determination of aortic pulse wave velocity from waveform decomposition of the central aortic pressure pulse

Aortic pulse wave velocity (PWV), calculated from pulse transit time (PTT) using 2 separate pulse recordings over a known distance, is a significant biomarker of cardiovascular risk. This study evaluates a novel method of determining PTT from waveform decomposition of central aortic pressure using a single pulse measurement. Aortic pressure was estimated from a transformed radial pulse and decomposed into forward and backward waves using a triangular flow wave. Pulse transit time was determined from cross-correlation of forward and backward waves. Pulse transit time, representing twice the PTT between 2 specific sites, was compared with independent measurements of carotid-femoral PTT in a cohort of 46 subjects (23 females; age 57+/-14 years). Linear regression between measured PTT (y; milliseconds) and calculated PTT (x; milliseconds) was y=1.05x-2.1 (r=0.67; P<0.001). This model was tested in a separate group of 44 subjects (21 females; age 55+/-14 years) by comparing measured carotid-femoral PWV (y; meters per second) and PWV calculated using the estimated value of PTT (eTR/2) and carotid femoral distance (x; meters per second; y=1.21x-2.5; r=0.82; P<0.001). Findings indicate that the time lag between the forward and backward waves obtained from the decomposition of aortic pressure wave can be used to determine PWV along the aortic trunk and shows good agreement with carotid-femoral PWV. This technique can be used as a noninvasive and nonintrusive method for measurement of aortic PWV using a single pressure recording.     

Aortic pulse wave velocity in subjects with aortic valve sclerosis

Background: Aortic stiffness is an independent risk factor for cardiovascular events and mortality. The measurement of pulse‐wave velocity (PWV) is the most simple, noninvasive, and robust method to determine aortic stiffness. Whether aortic stiffness contributes to aortic valve sclerosis (AVS) remains unknown. The aim of the present study was to examine the relationship between PWV and AVS in subjects free of clinically evident atherosclerotic disease. Methods: We enrolled 62 patients (48 men; age 65 ± 8 years) diagnosed with AVS and an additional 62 age‐, hypertension‐, diabetes mellitus‐, and history of smoking‐matched subjects without AVS. Applanation tonometry was applied to assess the augmentation index and aortic PWV. The subjects with symptomatic vascular disease were excluded from the study. AVS was defined by echocardiography as thickening and calcification of the normal trileaflet aortic valve without obstruction to the left ventricular outflow. Results: There was no significant difference between the two groups regarding the aortic PWV and augmentation index (11.7±3.3 vs 11.8±3.7, P=0.85; 28.0±9.4 vs 25.0±8.6, P=0. 17, respectively). The presence of AVS was significantly correlated with ejection fraction (r=0.211, P=0.011), male gender (r=0.362, P=0.0001), and age (r=0.200, P=0.026). Conclusions: The lack of an association between the aortic PWV and AVS suggests that AVS is a complex phenomenon consisting of several distinct processes, related to both atherosclerotic and nonatherosclerotic processes.     

估算的脉搏波传导速度与臂踝脉搏波传导速度的分布及一致性分析

目的观察估算的脉搏波传导速度(ePWV)和臂踝脉搏波传导速度(baPWV)在开滦研究人群中的分布特征并分析二者的一致性(差异及关联)。方法选择参加baPWV检测且基线资料完整的43 235例开滦集团公司职工作为观察人群。将研究对象按有无传统心血管危险因素分为风险人群和正常人群。在两人群中分别采用多元线性回归建立baPWV与年龄、年龄的平方、平均动脉压(MAP)的回归方程,并以此分别计算两人群的ePWV。观察ePWV和baPWV在人群中的分布特征并采用配对样本t检验和线性回归分析二者的差异和关联。结果在正常人群中,ePWV与baPWV分别为11.38±0.70 m/s和12.90±1.17 m/s;在风险人群中,ePWV与baPWV分别为14.29±1.85 m/s和15.74±1.76 m/s。无论在正常人群还是风险人群中,ePWV与baPWV均随年龄的增加而增加,男性的ePWV与baPWV均高于女性。同时,baPWV略高于ePWV(P0.01),在正常人群和风险人群中,二者平均差值分别为1.80 m/s和2.17 m/s。线性回归分析结果提示,二者在总人群、正常人群和风险人群中的线性R~2分别为0.428、0.279和0.388。结论 ePWV与baPWV具有相似的年龄、性别分布特征。二者差值相对较小且具有良好的线性关联。因此,ePWV可作为baPWV的良好替代指标。     

Relationship between brachial‐ankle pulse wave velocity and invasively measured aortic pulse pressure

Although brachial‐ankle pulse wave velocity (baPWV) has been widely used as an index of arterial stiffness, no consensus exists about whether baPWV can reflect central aortic stiffness. The authors investigated the association between baPWV and invasively measured aortic pulse pressure (APP) in a total of 109 consecutive patients (mean age, 62.3 ± 11.3 years; 67.9% men). Most patients (91%) had obstructive coronary artery disease, and mean baPWV and APP values were 1535 ± 303 cm/s and 66.8 ± 22.5 mm Hg, respectively. In univariate analysis, there was a significant linear correlation between baPWV and APP (r = .635, P < .001). The correlation between baPWV and APP remained significant even after controlling for potential confounders (β = 0.574, P < .001; R² = .469). Arterial stiffness measured by baPWV showed a strong positive correlation with invasively measured APP, independent of clinical confounders. Therefore, baPWV can be a good marker of central aortic stiffness.