Longitudinal Changes of Input Impedance, Pulse Wave Velocity, and Wave Reflection in a Middle-Aged Population: The Asklepios Study

Update on the Use of Pulse Wave Velocity to Measure Age-Related Vascular Changes

PURPOSE OF REVIEW

Pulse wave velocity (PWV) is an important and well-established measure of arterial stiffness that is strongly associated with aging. Age-related alterations in the elastic properties and integrity of arterial walls can lead to cardiovascular disease. PWV measurements play an important role in the early detection of these changes, as well as other cardiovascular disease risk factors, such as hypertension. This review provides a comprehensive summary of the current knowledge of the effects of aging on arterial stiffness, as measured by PWV.

RECENT FINDINGS

This review highlights recent findings showing the applicability of PWV analysis for investigating heart failure, hypertension, and other cardiovascular diseases, as well as cerebrovascular diseases and Alzheimer's disease. It also discusses the clinical implications of utilizing PWV to monitor treatment outcomes, various challenges in implementing PWV assessment in clinical practice, and the development of new technologies, including machine learning and artificial intelligence, which may improve the usefulness of PWV measurements in the future. Measuring arterial stiffness through PWV remains an important technique to study aging, especially as the technology continues to evolve. There is a clear need to leverage PWV to identify interventions that mitigate age-related increases in PWV, potentially improving CVD outcomes and promoting healthy vascular aging.

Aortic Characteristic Impedance and Suspected Mild Cognitive Impairment in a Community-Based Healthy Population

BACKGROUND

Aging of the proximal aorta can lead to increased pressure and flow pulsatility in the cerebral microcirculation, which may cause cognitive impairment. This study investigated the association between aortic characteristic impedance (Zc), an indicator of regional stiffness of the proximal aorta, and suspected mild cognitive impairment (MCI), compared with carotid-femoral pulse wave velocity (CFPWV).

METHODS AND RESULTS

A total of 1461 healthy community residents (46.4% men; age range, 35-96 years [mean±SD, 59.9±11.8 years]) without a history of cardiovascular events or stroke were included in the study. Zc was estimated using applanation tonometry and echocardiography. Cognitive function was assessed using the Mini-Mental State Examination. Education-adjusted cut points were used to define suspected MCI. Subjects with suspected MCI (n=493 [33.7%]) had significantly higher Zc and CFPWV than those without. In multivariable analysis, both Zc and CFPWV were inversely associated with Mini-Mental State Examination score. Zc (odds ratio per 1 SD, 1.22 [95% CI, 1.09-1.37] and CFPWV (odds ratio per 1 SD, 1.18 [95% CI, 1.01-1.38]) was also significantly associated with suspected MCI, after adjusting for age, sex, education level, mean arterial pressure, hypertension, diabetes, low-density lipoprotein cholesterol, and smoking status. In joint analysis, Zc was significantly associated with suspected MCI, but CFPWV was not. In the age subgroups of <50 years and 50 to 70 years, only Zc was significantly associated with suspected MCI.

CONCLUSIONS

This study found that Zc was significantly associated with Mini-Mental State Examination score and suspected MCI, especially in younger and middle-aged adults. These findings suggest that Zc may be a useful biomarker for identifying individuals at risk for MCI.

Myocardial Work in Middle-Aged Adults with Overweight and Obesity: Associations with Sex and Central Arterial Stiffness

We explored global myocardial work index (GWI), a novel measure of myocardial function that integrates left ventricular (LV) hemodynamic load, in relation to sex and increased body mass index (BMI). We used data from 467 individuals (61% women, average age 47 ± 9 years and BMI 31.2 kg/m2) without known cardiac disease. Central arterial function was analysed by applanation tonometry. GWI was calculated from global longitudinal strain (GLS) and post-echocardiography supine blood pressure (BP). Covariables of GWI were identified in linear regression analyses. Women had higher BMI, aortic augmentation pressure (12 ± 7 vs. 8 ± 6 mmHg), LV GLS (20.0 ± 2.8 vs. 18.8 ± 2.8%), and GWI (2126 ± 385 vs. 2047 ± 389 mmHg%) than men (all p < 0.05). In univariable analyses, higher GWI was associated with female sex, higher age, systolic BP, LV wall stress, LV ejection fraction, left atrial size, LV ejection time, and with lower waist circumference (all p < 0.05). In multivariable analysis, adjusting for these correlates, female sex remained independently associated with higher GWI (β = 0.13, p = 0.007). After additional adjustment for aortic augmentation pressure or central pulse pressure, this association became non-significant. In conclusion, the higher GWI in women compared to men was mainly explained by increased LV workload due to higher aortic augmentation pressure in women.

Vascular ageing: moving from bench towards bedside

Prevention of cardiovascular disease (CVD) remains one of the largest public health challenges of our time. Identifying individuals at increased cardiovascular risk at an asymptomatic, sub-clinical stage is of paramount importance for minimizing disease progression as well as the substantial health and economic burden associated with overt CVD. Vascular ageing (VA) involves the deterioration in vascular structure and function over time and ultimately leads to damage in the heart, brain, kidney, and other organs. Vascular ageing encompasses the cumulative effect of all cardiovascular risk factors on the arterial wall over the life course and thus may help identify those at elevated cardiovascular risk, early in disease development. Although the concept of VA is gaining interest clinically, it is seldom measured in routine clinical practice due to lack of consensus on how to characterize VA as physiological vs. pathological and various practical issues. In this state-of-the-art review and as a network of scientists, clinicians, engineers, and industry partners with expertise in VA, we address six questions related to VA in an attempt to increase knowledge among the broader medical community and move the routine measurement of VA a little closer from bench towards bedside.

Vascular function in hypertension: does gender dimension matter?

Blood pressure and vascular ageing trajectories differ between men and women. These differences develop due to sex-related factors, attributable to sex chromosomes or sex hormones, and due to gender-related factors, mainly related to different sociocultural behaviors. The present review summarizes the relevant facts regarding gender-related differences in vascular function in hypertension. Among sex-related factors, endogenous 17ß-estradiol plays a key role in protecting pre-menopausal women from vascular ageing. However, as vascular ageing (preceding and inducing hypertension) has a steeper increase in women than in men starting already from the third decade, it is likely that gender-related factors play a prominent role, especially in the young. Among gender-related factors, psychological stress (including that one related to gender-based violence and discrimination), depression, some psychological traits, but also low socioeconomic status, are more common in women than men, and their impact on vascular ageing is likely to be greater in women. Men, on the contrary, are more exposed to the vascular adverse consequences of alcohol consumption, as well as of social deprivation, while "toxic masculinity" traits may result in lower adherence to lifestyle and preventive strategies. Unhealthy diet habits are more prevalent in men and smoking is equally prevalent in the two sexes, but have a disproportional negative effect on women's vascular health. In conclusion, given the major and complex role of gender-related factors in driving vascular alterations and blood pressure patterns, gender dimension should be systematically integrated into future research on vascular function and hypertension and to tailor cardiovascular prevention strategies.

Longitudinal Hemodynamic Correlates of and Sex Differences in the Evolution of Blood Pressure Across the Adult Lifespan: The Framingham Heart Study

Background Systolic blood pressure increases with age after midlife, particularly in women, and contributes to development of wide pulse pressure hypertension in middle-aged and older adults. Relative contributions of aortic stiffness and premature wave reflection to increases in pulse pressure remain controversial. Methods and Results We evaluated visit-specific values and change in key correlates of pulse pressure, aortic characteristic impedance, forward and backward wave amplitude, and global reflection coefficient, at 3 sequential examinations of the Framingham Generation 3 (N=4082), Omni-2 (N=410), and New Offspring Spouse (N=103) cohorts (53% women). Data were analyzed using repeated-measures linear mixed models adjusted for age, sex, and risk factor exposures. Pulse pressure increased markedly with age after midlife (age and age-squared terms, P<0.0001), particularly in women (age slope 3.1±0.2 mm Hg/decade higher in women, P<0.0001). In sex-specific models, change in pulse pressure was closely related (all P<0.0001) to baseline (6.7±0.2 and 7.3±0.2 mm Hg/SD in men and women, respectively) and change (11.8±0.1 and 11.7±0.1 mm Hg/SD) in forward wave amplitude, whereas relations with baseline (2.1±0.15 and 2.0±0.14 mm Hg/SD) and change (4.0±0.13 and 3.4±0.11 mm Hg/SD) in global reflection coefficient were weaker. Global reflection coefficient fell as aortic characteristic impedance increased (P<0.0001), consistent with the hypothesis that impedance matching reduces relative wave reflection in the arterial system. Conclusions Proximal aortic stiffening, as assessed by higher aortic characteristic impedance and larger forward wave amplitude, is strongly associated with longitudinal increase in pulse pressure, especially in women, whereas wave reflection has more modest relations.

Ascending aorta dilatation reduces the influence of elevated pulse pressure on left ventricular hypertrophy: findings from a Chinese elderly hypertensive population

OBJECTIVE

To determine the role of ascending aorta dilatation in the relationship between pulse pressure (PP) and left ventricular (LV) hypertrophy.

METHODS

A total of 1556 Chinese elderly hypertensive patients were retrospectively studied. Transthoracic echocardiography was used to obtain the aortic and cardiac structure measurements. In addition, brachial blood pressure was measured, and total arterial compliance, systemic vascular resistance, arterial elastance, and end-systolic LV elastance were calculated. The participants were divided into four groups according to the status of ascending aortic diameter and PP.

RESULTS

LV mass index increased in succession in the four groups, i.e., the group with the normal aorta and lower PP, with the normal aorta and higher PP, with aortic dilatation and lower PP, and with aortic dilatation and higher PP (P _trend < 0.001). Total arterial compliance^-1, arterial elastance, and end-systolic LV elastance were slightly higher in the individuals with normal aorta compared to those with aortic dilatation, regardless of PP being lower or higher (P < 0.01). Compared to the group with the normal aorta and lower PP, individuals with aortic dilatation had a significantly increased multivariable adjusted risk of LV hypertrophy, and higher PP further exacerbated this risk [aortic dilatation with lower PP (OR = 1.75, 95% CI: 1.01-3.04) and aortic dilatation with higher PP (OR = 3.42, 95% CI: 2.03-5.77)]. In the relation between PP and LV mass index (β = 0.095, P < 0.001), -41.3% of the total effect was attributable to mediation by ascending aortic diameter (P < 0.0001).

CONCLUSIONS

In Chinese elderly patients with hypertension, ascending aorta dilatation could reduce the influence of elevated PP on LV hypertrophy.

Determinants of arterial elastic function in middle-aged and elderly people: A population-based cross-sectional study from a low-income population in China

Background

Arterial stiffness is closely associated with the occurrence of many cardiovascular and cerebrovascular diseases. However, the risk factors and mechanisms related to arterial stiffness development have only been partially elucidated. We aimed to describe arterial elastic function and its influencing factors in middle-aged and elderly people in rural China.

Methods

This was a cross-sectional study conducted among residents, aged ≥45 years, of Tianjin, China, between April and July 2015. Data regarding participant demographics, medical history, lifestyle, and physical examination results were collected and assessed the association with arterial elastic function using linear regression.

Results

Of the 3,519 participants, 1,457 were male (41.4%). Brachial artery distensibility (BAD) decreased by 0.5%/mmHg with every 10-year increment in age. The mean BAD value was 0.864%/mmHg lower in women than in men. With each unit increase in mean arterial pressure, the BAD decreased by 0.042%/mmHg. In patients with hypertension or diabetes, the BAD decreased by 0.726 and 0.183%/mmHg, respectively, compared with those without hypertension or diabetes. For each unit increase in triglyceride (TG) level, the mean BAD increased by 0.043%/mmHg. With each increase in body mass index (BMI) category, the BAD increased by 0.113%/mmHg. Brachial artery compliance (BAC) decreased by 0.007 ml/mmHg with each 10-year increase in age, and brachial artery resistance (BAR) increased by 30.237 dyn s^-1 cm^-5. The mean BAC in women was 0.036 ml/mmHg lower and the mean BAR was 155.231 dyn s^-1 cm^-5 higher in women than in men. In individuals with hypertension, the mean BAC decreased by 0.009 ml/mmHg and the mean BAR increased by 26.169 dyn s^-1 cm^-5. With each increase in BMI category, the mean BAC increased by 0.005 ml/mmHg and the mean BAR decreased by 31.345 dyn s^-1 cm^-5. For each unit increase in TG level, the mean BAC increased by 0.001 ml/mmHg.

Conclusion

These findings indicate that age, sex, mean arterial pressure, BMI, diabetes, hypertension, and TG level are independently associated with the components of peripheral arterial elasticity. Understanding the factors influencing arterial stiffness is important for developing interventions to minimize arterial aging and cardiovascular and cerebrovascular diseases caused by arterial aging.

Relation of Pulse Wave Velocity to Contemporaneous and Historical Blood Pressure in Female Twins

BACKGROUND

An association between blood pressure and aortic stiffness is well known, but ambiguity remains as to whether one precedes the other. This study aimed to investigate the association of aortic stiffness with contemporaneous versus historic blood pressure and direction of causality between aortic stiffening and hypertension in female twins.

METHODS

Aortic stiffness, measured by carotid-femoral pulse wave velocity (PWV), and mean arterial pressure (MAP) was recorded in 2037 female TwinsUK participants (mean age: 62.4±9.7 years) at a single time point. A subset of 947 participants had repeat PWV and MAP measures (mean interval 5.5±1.7 years) with additional historic MAP (mean interval 6.6±3.3 years before baseline).

RESULTS

Cross-sectional multivariable linear regression analysis confirmed PWV significantly associated with age and MAP. In longitudinal analysis, annual progression of PWV was not associated with historic MAP (standardized beta coefficient [β]=-0.02, P=0.698), weakly associated with baseline MAP (β=0.09, P=0.049) but strongly associated with progression (from baseline to most recent measurement) of MAP (β= 0.26, P<0.001). Progression of MAP associated with both baseline and progression of PWV (β=0.13, P=0.003 and β=0.24, P<0.001, respectively).

CONCLUSIONS

Progression of aortic stiffness associates more strongly with contemporaneous MAP compared with historic MAP. In contrast, progression of MAP is associated with prior arterial stiffness. These findings suggest a bidirectional relationship between arterial stiffness and blood pressure, and that lowering blood pressure may prevent a cycle of arterial stiffening and hypertension.

Association of Adverse Childhood Experiences and Social Isolation With Later-Life Cognitive Function Among Adults in China

IMPORTANCE

Studies investigating the association of threat-related and deprivation-related adverse childhood experiences (ACEs) with later-life cognitive decline are lacking.

OBJECTIVES

To evaluate the independent association of threat-related and deprivation-related ACEs with cognitive decline over time among middle-aged and older Chinese adults and to examine the modifying role of social isolation in such associations.

DESIGN, SETTING, AND PARTICIPANTS

This prospective cohort study used cognitive data from the China Health and Retirement Longitudinal Study (CHARLS) baseline survey that was administered between June 1, 2011, and March 31, 2012, and the CHARLS follow-up survey administered between July 1 and September 30, 2015. The life history survey with information of ACEs was additionally administered between June 1 and December 31, 2014. Statistical analysis was performed from March 1 to July 31, 2022. The study population consisted of middle-aged and older adults (age range, 45-97 years) with complete data on ACEs and 2 cognitive assessments and without cognitive impairment at baseline.

EXPOSURES

Five threat-related ACEs (ie, physical abuse, household substance abuse, domestic violence, unsafe neighborhood, and bullying) and 5 deprivation-related ACEs (ie, emotional neglect, household mental illness, incarcerated household member, parental separation or divorce, and parental death) before 17 years of age were queried by questionnaires. The cumulative scores of the 2 ACE dimensions were calculated and grouped into 3 categories as 0, 1, and 2 or more in main analyses.

MAIN OUTCOMES AND MEASURES

Cognitive function was measured by episodic memory and executive function. Global cognition was further calculated as the total score of these 2 dimensions. The raw scores of each cognitive test were standardized to z scores using baseline means and SDs. Linear mixed-effects models were constructed to examine the association between 2 dimensions of ACEs and the rate of annual cognitive decline. The modifying role of baseline social isolation in such associations was assessed with 3-way interaction tests.

RESULTS

Of the 6466 participants included in main analyses, 3301 (51.1%) were men and the mean (SD) age was 57.2 (8.3) years. Compared with no exposures, experience of 1 deprivation-related ACE was associated with faster cognitive decline in global cognition (β = -0.012 [95% CI, -0.022 to -0.002] SD/y) and executive function (β = -0.010 [95% CI, -0.020 to -0.00002] SD/y), whereas individuals with at least 2 childhood deprivations had faster cognitive declines in all cognitive tests (β = -0.035 [95% CI, -0.050 to -0.019] SD/y for global cognition; β = -0.047 [95% CI, -0.068 to -0.025] SD/y for episodic memory; β = -0.019 [95% CI, -0.034 to -0.004] SD/y for executive function). However, such an association was not observed for threat-related ACEs. In addition, baseline social isolation was a significant modifier in the associations between deprivation-related ACEs and cognitive declines in global cognition (β = -0.033 [95% CI, -0.061 to -0.005] SD/y; P = .02 for 3-way interaction) and executive function (β = -0.032 [95% CI, -0.059 to -0.005] SD/y; P = .02 for 3-way interaction).

CONCLUSIONS AND RELEVANCE

Deprivation-related ACEs, but not threat-related ACEs, were associated with faster decline in later-life cognitive function, whereas social isolation could modify such detrimental impact. These findings highlight the potential benefits of promoting social integration in maintaining later-life cognitive function among individuals who have experienced childhood deprivation.

Sex differences in arterial hypertension

There is strong evidence that sex chromosomes and sex hormones influence blood pressure (BP) regulation, distribution of cardiovascular (CV) risk factors and co-morbidities differentially in females and males with essential arterial hypertension. The risk for CV disease increases at a lower BP level in females than in males, suggesting that sex-specific thresholds for diagnosis of hypertension may be reasonable. However, due to paucity of data, in particularly from specifically designed clinical trials, it is not yet known whether hypertension should be differently managed in females and males, including treatment goals and choice and dosages of antihypertensive drugs. Accordingly, this consensus document was conceived to provide a comprehensive overview of current knowledge on sex differences in essential hypertension including BP development over the life course, development of hypertension, pathophysiologic mechanisms regulating BP, interaction of BP with CV risk factors and co-morbidities, hypertension-mediated organ damage in the heart and the arteries, impact on incident CV disease, and differences in the effect of antihypertensive treatment. The consensus document also highlights areas where focused research is needed to advance sex-specific prevention and management of hypertension.

Central Pressure Waveform-Derived Indexes Obtained From Carotid and Radial Tonometry and Brachial Oscillometry in Healthy Subjects (2–84 Y): Age-, Height-, and Sex-Related Profiles and Analysis of Indexes Agreement

Aortic blood pressure (aoBP) waveform-derived indexes could provide valuable (prognostic) information over and above cardiovascular risk factors (CRFs). To obtain aoBP waveform-characteristics, several (i) techniques, (ii) recording sites, (iii) pressure-only waveform analysis mathematical approaches [e.g., pulse wave analysis (PWA), wave separation analysis (WSA)], and (iv) indexes [augmentation pressure and index (AP and AIx), forward (Pf) and backward (Pb) components of aoBP, reflection magnitude (RM), and reflection index (Rix)], were proposed. An accurate clinical use of these indexes requires knowing their physiological age-related profiles and the expected values for a specific subject. There are no works that have characterized waveform-derived indexes profiles in large populations considering: (i) as a continuous, data from different age stages (childhood, adolescence, and adulthood), (ii) complementary indexes, (iii) data obtained from different techniques and approaches, and (iv) analyzing potential sex- and body height (BH)-related differences. In addition, (v) there is a lack of normative data (reference intervals, RIs) for waveform-derived indexes.

Aortic Root Diameter and Arterial Stiffness: Conjoint Relations to the Incidence of Cardiovascular Disease in the Framingham Heart Study

[Figure: see text].

Sex and Gender Aspects in Vascular Ageing - Focus on Epidemiology, Pathophysiology, and Outcomes

Sex and gender are important modifiers of cardiovascular system physiology, pathophysiology, and disease development. The atherosclerosis process, together with the progressive loss of arterial elasticity with age, is a major factor influencing the development of overt cardiovascular, renal, and cerebrovascular disease. While differences between women and men in epidemiology and pathophysiology of vascular ageing are increasingly reported, sex-disaggregated data are still scarcely available for prospective studies. A better knowledge of sex differences in physiological ageing as well as in disease-related changes in vascular ageing trajectories is crucial to avoid misdiagnosis and mistreatment. This review presents key concepts and knowledge gaps identified in vascular ageing due to gonadal function, vascular physiology, pathophysiology, psychosocial factors, pregnancy, and prognostic relevance. Gender roles determine the effectiveness of any cardiovascular preventive strategy and acceptance for non-invasive or invasive diagnostics and therapeutics. Gender differences in health behaviour, also due to sociocultural norms conditioned by society, contribute to behaviours that may lead to premature arterial vascular ageing. These include differences in risk behaviours like smoking, diet, exercise, and in stress, but also conditions such as housing, noise pollution, poverty, disability, and any kind of stigmatisation. The VascAgeNet Gender Expert Group aims to advance the use of non-invasive vascular ageing measures in routine clinical settings by providing facts to fill in the gaps concerning sex and gender differences at each step of this process, and to search for solutions.

Discrepancies in Observed and Predicted Longitudinal Change in Central Hemodynamic Measures: The Framingham Heart Study

[Figure: see text].

Technical Validation and Usability of a Portable Ultrasound-Based System for Carotid Assessment of Vascular Ageing: A Pilot Study

OBJECTIVE

The objective of this work was to investigate technical validation and usability of an innovative, technically simple, easy-to-use, and portable integrated system to assess carotid function and structure by ultrasound.

METHODS

The studied system integrated a hardware (the Interson SP-L01 embedded ultrasound probe [Interson, Pleasanton, CA, USA]) and a software measuring the instantaneous diameter of the carotid artery in real-time from B-mode ultrasound image sequences (Carotid Studio, by Quipu Srl [Pisa, Italy]). Technical validation was evaluated by intra-operator reproducibility of two measurements acquired by an expert operator, and agreement with state-of-the-art technique (Mylab25 by Esaote SpA [Genova, Italy], Carotid Studio 4.3 by Quipu Srl) was evaluated in laboratory settings in 12 healthy volunteers; usability of the portable integrated system was investigated by administering questionnaires to users and the results were reported with scores based on a five-point scale.

RESULTS

Twelve (12) healthy volunteers (five men, mean age 44.5±13.6 years, free of cardiovascular disease or risk factors), were recruited. Agreement with state-of-the-art technique was satisfactory, with no significant bias. Coefficient of variation (intra-operator reproducibility) was 3.2% (2.5% SD) for intima-media thickness, 0.9% (0.7% SD) for diameter, and 2.5% (2.2% SD) for distension. Usability questionnaires showed an overall positive judgement of the integrated system with respect to the traditional one, obtaining an average score greater than 4 (on a five-point scale).

CONCLUSIONS

A portable, innovative prototype to easily assess ultrasound carotid parameters of vascular ageing was successfully designed, developed, and demonstrated to be comparable with state-of-the art technique. Usability was also satisfactory.