An updated clinical primer on large artery mechanics: implications of pulse waveform analysis and arterial tonometry

Central blood pressure and peripheral augmentation index following acute submaximal arm versus leg exercise

BACKGROUND

Aerobic exercises like running and cycling may lower cardiovascular disease (CVD) risk through favorable effects on central blood pressure and vascular function. Arm ergometry is a popular exercise modality used in rehabilitation settings, but little is known regarding the central hemodynamic and vascular effects of this form of exercise.

PURPOSE

To compare the acute effects of leg versus arm exercise on central blood pressure and vascular function.

METHODS

Twenty-one participants (n = 11 female, Age 21 ± 3, BMI 24.5 ± 3.2 kg/m2) completed two visits to the Human Performance Laboratory. Central systolic blood pressure (cSBP), central diastolic blood pressure (cDBP), and peripheral augmentation index (pAIx) were measured using a brachial oscillometric blood pressure cuff with measures being taken before and after 20 min of acute moderate-intensity (submaximal) arm or leg cycling exercise.

RESULTS

There was a condition-by-time interaction for pAIx (p = 0.011). pAIx slightly increased following arm exercise but significantly decreased following leg exercise. There was a condition-by-time interaction for cDBP (p = 0.011). cDBP significantly decreased following arm exercise but increased immediately following leg exercise. There was no condition-by-time interaction for cSBP (p = 0.721). There were similar acute increases in cSBP immediately post-exercise for both conditions.

CONCLUSION

Arm exercise increased pAlx and decreased cDBP compared to leg exercise. As an increase in pAIx may increase left ventricular work and a reduction in cDBP may reduce coronary perfusion pressure, these findings suggest that a single bout of arm exercise may not have the same favorable acute effect on central hemodynamic load as a single bout of leg exercise.

The association between the urinary chromium and blood pressure: a population-based study

BACKGROUND AND AIM

The impact of trace elements and heavy metals on human health has attracted widespread attention. However, the correlation between urinary chromium concentrations and blood pressure remains unclear and inadequately reported, and the aim of this study was to investigate the relationship between urinary chromium concentrations and blood pressure in adults in the United States (US).

METHODS

We utilized data from the National Health and Nutrition Examination Survey (NHANES) 2017-2018 for this study. Multivariate logistic regression and multivariate linear regression were used to explore the association of urinary chromium concentrations with hypertension and blood pressure. Additionally, we also performed subgroup analysis and restricted cubic splines (RCS).

RESULTS

A total of 2958 participants were enrolled in this study. The overall mean systolic blood pressure and diastolic blood pressure were 123.98 ± 0.60, 72.66 ± 0.57 mmHg, respectively. The prevalence of hypertension was found in 41.31% of the whole participants. In the fully adjusted model, we did not observe a correlation between urinary chromium concentrations and the risk of hypertension and systolic blood pressure. However, we found a negative association between urinary chromium concentrations and diastolic blood pressure. In subgroup analysis, we observed a positive association between urinary chromium and the risk of hypertension among participants older than 60 years of age and those who were Non-Hispanic Black. The interaction term highlighted the influence of age and race on this positive association. We also found a negative association of urinary chromium with diastolic blood pressure in male, participants who were current smokers, overweight, and other races, as well as those without alcohol use and anti-hypertensive drug use. However, the interaction term only revealed the influence of alcohol consumption on the negative association.

CONCLUSION

Our study suggested that urinary chromium concentrations may show a negative association with diastolic blood pressure and this association was significantly dependent on alcohol consumption. Besides, a positive association between urinary chromium and the risk of hypertension was also found among participants older than 60 years of age and those who were Non-Hispanic Black.

Validation of a Suprasystolic Cuff System for Static and Dynamic Representation of the Central Pressure Waveform

BACKGROUND

Noninvasive pulse waveform analysis is valuable for central cardiovascular assessment, yet controversies persist over its validity in peripheral measurements. Our objective was to compare waveform features from a cuff system with suprasystolic blood pressure hold with an invasive aortic measurement.

METHODS AND RESULTS

This study analyzed data from 88 subjects undergoing concurrent aortic catheterization and brachial pulse waveform acquisition using a suprasystolic blood pressure cuff system. Oscillometric blood pressure (BP) was compared with invasive aortic systolic BP and diastolic BP. Association between cuff and catheter waveform features was performed on a set of 15 parameters inclusive of magnitudes, time intervals, pressure-time integrals, and slopes of the pulsations. The evaluation covered both static (subject-averaged values) and dynamic (breathing-induced fluctuations) behaviors. Peripheral BP values from the cuff device were higher than catheter values (systolic BP-residual, 6.5 mm Hg; diastolic BP-residual, 12.4 mm Hg). Physiological correction for pressure amplification in the arterial system improved systolic BP prediction (r2=0.83). Dynamic calibration generated noninvasive BP fluctuations that reflect those invasively measured (systolic BP Pearson R=0.73, P<0.001; diastolic BP Pearson R=0.53, P<0.001). Static and dynamic analyses revealed a set of parameters with strong associations between catheter and cuff (Pearson R>0.5, P<0.001), encompassing magnitudes, timings, and pressure-time integrals but not slope-based parameters.

CONCLUSIONS

This study demonstrated that the device and methods for peripheral waveform measurements presented here can be used for noninvasive estimation of central BP and a subset of aortic waveform features. These results serve as a benchmark for central cardiovascular assessment using suprasystolic BP cuff-based devices and contribute to preserving system dynamics in noninvasive measurements.

Rethinking Fluid Responsiveness during Septic Shock: Ameliorate Accuracy of Noninvasive Cardiac Output Measurements through Evaluation of Arterial Biomechanical Properties

Beat-to-beat estimates of cardiac output from the direct measure of peripheral arterial blood pressure rely on the assumption that changes in the waveform morphology are related to changes in blood flow and vasomotor tone. However, in septic shock patients, profound changes in vascular tone occur that are not uniform across the entire arterial bed. In such cases, cardiac output estimates might be inaccurate, leading to unreliable evaluation of fluid responsiveness. Pulse wave velocity is the gold-standard method for assessing different arterial biomechanical properties. Such methods might be able to guide, personalize and optimize the management of septic patients.

Estimation of Central Systolic Blood Pressure from Peripheral Pressure Waves using a Novel Second Systolic Pressure-Based Method in Normal and Heritable Hypercholesterolemic Rabbits

AIM

Central systolic blood pressure (cSBP) was closely related to hypertension-related organ damage rather than peripheral systolic blood pressure (pSBP). We aimed to estimate cSBP from pSBP without generalized transfer function in normal and Kurosawa and Kusanagi-hypercholesterolemic (KHC) rabbits aged 12 months.

METHODS

Two catheter-tip transducers were advanced into the ascending aorta (AA) and distal end of the right brachial artery (Br) through the right common carotid and right radial arteries, respectively, under pentobarbital anesthesia. Pressure waves in response to the intravenous administration of angiotensin II and sodium nitroprusside were simultaneously recorded in AA and Br under regular cardiac pacing.

RESULTS

The first (pSBP) and second peaks (pSBP2) of the brachial blood pressure and their average (pSBPm) were significantly correlated with cSBP, despite Murgo's wave pattern of central pressure waves in both rabbit groups. In Bland-Altman plot and its modification as a function of the peripheral augmentation index (pAI) analyses, the differences between pSBP and cSBP decreased, and those between pSBP2 and cSBP increased significantly in their average- or pAI-dependent manner, with undeniable mean biases in both rabbit groups. When the same analyses for SBPm were performed instead, the mean bias was around zero, with reduced variance in the two rabbit groups. The observed pressure or pAI-dependent systematic biases for pSBP and pSBP2 disappeared, representing the precise feature of pSBPm as a cSBP estimate.

CONCLUSIONS

We conclude that pSBPm could be more precise than pSBP2 as a cSBP estimate, irrespective of blood pressure levels, pAI, or the presence of atherosclerosis.

Amplitude and phase measurements from harmonic analysis may lead to new physiologic insights: lower body negative pressure photoplethysmographic waveforms as an example

The photoplethysmographic (PPG) waveform contains hemodynamic information in its oscillations. We provide a new method for quantitative study of the waveform morphology and its relationship to the hemodynamics. A data adaptive modeling of the waveform shape is used to describe the PPG waveforms recorded from ear and finger. Several indices, based on the phase and amplitude information of different harmonics, are proposed to describe the PPG morphology. The proposed approach is illustrated by analyzing PPG waveforms recorded during a lower body negative pressure (LBNP) experiment. Different phase and amplitude dynamics are observed during the LBNP experiment. Specifically, we observe that the phase difference between the high order harmonics and fundamental components change more significantly when the PPG signal is recorded from the ear than the finger at the beginning of the study. In contrast, the finger PPG amplitude changes more when compared to the ear PPG during the recovery period. A more complete harmonic analysis of the PPG appears to provide new hemodynamic information when used during a LBNP experiment. We encourage other investigators who possess modulated clinical waveform data (e.g. PPG, arterial pressure, respiratory, and autonomic) to re-examine their data, using phase information and higher harmonics as a potential source of new insights into underlying physiologic mechanisms.

A clinical algorithm to determine target blood pressure in the elderly: evidence and limitations from a clinical perspective

As the elderly population is growing rapidly, management of hypertension in South Korea faces major challenges because the proportion of elderly hypertension patients is also increasing. The characteristics of this population are also much more complex than younger patients. Elderly hypertension is characterized by wide variations in (1) fitness or biological age, (2) white-coat effect, (3) poor functional status or frailty, (4) dependency in activities of daily living or institutionalization, (5) orthostatic hypotension, and (6) multiple comorbidities. All of these should be considered when choosing optimal target blood pressure in individual patients. Recent randomized clinical trials have shown that the benefits of intensive blood pressure control for elderly patients is greater than previously thought. For generalization of these results and implementation of the guidelines based on these studies, defining the clinician's role for individualization is critically important. For individualized decisions for target blood pressure (BP) in the elderly with hypertension, four components should first be checked. These consist of (1) the minimum requirement of functional status and capability of activities of daily living, (2) lack of harmful evidence by the target BP, (3) absence of white-coat hypertension, and (4) standing systolic BP ≥ 110 mmHg without orthostatic symptoms. Risk of decreased organ perfusion by arterial stenosis should be screened before starting intensive BP control. When the target BP differs among comorbidities, the lowest target BP should be given preference. After starting intensive BP lowering therapy, tolerability should be monitored, and the titration should be based on the mean level of blood pressure by office supplemented by out-of-office BPs. Applications of the clinical algorithms will be useful to achieve more standardized and simplified applications of target BP in the elderly.

Comparison of noninvasive continuous arterial blood pressure measured by NICAP with arterial line in elderly patients

BACKGROUND

Non-Invasive Continuous Arterial Pressure system (NICAP) allows continuous monitoring, timely detection of hypotension, and avoiding risks from invasive procedures. A previous study showed good comparability of NICAP with arterial line in people with no evidence of cardiovascular disease. Therefore, the goal of this study was to investigate whether NICAP could be accurately applied to elderly patients.

METHODS

In this single-centered observational study, forty-one patients above 65 undergoing elective surgeries requiring artery catheterizations were enrolled from July 17, 2020, to June 25, 2021. Radial artery cannulation and NICAP monitoring were started before anesthesia. Blood pressure during the anesthesia induction and the whole surgery, trend of blood pressure changes, time needed for establishing continuous monitoring, and complications were recorded.

RESULTS

A total of 6751 valid pairs of blood pressure measurements were analyzed. In the Bland-Altman analysis, the arithmetic means for systolic, diastolic, and mean arterial pressure were 2.2, 3.3, and 2.8 mmHg, respectively. NICAP and arterial line correlation coefficients for systolic, diastolic, and mean arterial pressure were 0.49, 0.33, and 0.45, respectively. In the trending analysis, the polar concordance rates at 30 degrees were 70.9% for systolic, 67.7% for diastolic, and 69.3% for mean arterial blood pressure. During the anesthesia induction, the arithmetic means for systolic, diastolic, and mean arterial pressure in the Bland-Altman analysis were 1.7, -0.2, and 0.5 mmHg, respectively. NICAP and arterial line correlation coefficients for systolic, diastolic, and mean arterial pressure were 0.78, 0.61 and 0.75, respectively. No severe complications occurred.

CONCLUSIONS

NICAP has a poor correlation with the arterial line in elderly patients for the whole surgery or during anesthesia induction. Moreover, it showed poor comparability in the detection of blood pressure change trends with arterial lines. Our findings suggest that NICAP might not be sufficiently accurate to be applied clinically in elderly patients with comorbidities. More accurate calibration and iteration are needed.

Hemodynamic response and pulse wave analysis after upper- and lower-body resistance exercise with and without blood flow restriction

Resistance exercise (RE) has been shown to elevate hemodynamics and pulse wave reflection. However, the effects of acute RE with blood flow restriction (BFR) on hemodynamics and pulse wave reflection are unclear. The purpose of this study was to evaluate the differences between upper- and lower-body RE with and without BFR on hemodynamics and pulse wave reflection. Twenty-three young resistance-trained individuals volunteered for the study. Hemodynamics and pulse wave reflection were assessed at rest, 10, 25, 40, and 55 min after either upper- or lower-body with or without BFR. The upper-body RE (URE) consisted of the latissimus dorsi pulldown and chest press; the lower-body RE (LRE) consisted of knee extension and knee flexion. The BFR condition consisted of four sets of 30, 15, 15, and 15 repetitions at 30% 1-repetition maximum (1RM) while the without BFR condition consisted of four sets of 8 repetitions at 70% 1RM. Heart rate, rate pressure product, and subendocardial viability ratio significantly (p < 0.05) increased after all exercises. Brachial and aortic systolic blood pressure (BP) significantly (p < 0.05) elevated after LRE while brachial and aortic diastolic BP significantly (p < 0.05) reduced after URE. Augmentation pressure, augmentation index (AIx), AIx normalized at 75 bpm, and wasted left ventricular pressure energy significantly (p < 0.05) increased after URE while transit time of reflected wave significantly (p < 0.05) decreased after LRE. URE places greater stress on pulse wave reflection while LRE results in greater responses in BP. Regardless of URE or LRE, the cardiovascular responses between BFR and without BFR are similar.HIGHLIGHTS High-load resistance exercise and low-load resistance exercise with blood flow restriction may produce similar cardiovascular responses.Upper-body resistance exercise generates greater changes on pulse wave reflections while lower-body resistance exercise induces greater elevations in systolic blood pressure.

Recognizable Clinical Subtypes of Obstructive Sleep Apnea After Ischemic Stroke: A Cluster Analysis

BACKGROUND AND PURPOSE

Obstructive sleep apnea (OSA) increases risk of stroke recurrence and mortality in ischemic stroke patients. However, equivocal treatment effects warrant further categorization of post-stroke OSA for risk stratification and individualized treatment planning.

METHODS

The study recruited 232 ischemic stroke patients with moderate-to-severe OSA admitted for inpatient rehabilitation consecutively. Latent class analysis was performed based on sex, age, smoking, daytime sleepiness, depression, obesity, sedative use, atrial fibrillation, diabetes, dyslipidemia, hypertension, recurrent stroke and dysphagia. The augmentation index, a marker of arterial stiffness, was measured by applanation tonometry.

RESULTS

A three-cluster model provided the best fit. Cluster 1 (n=84, 36.2%) was older in age, predominantly female, with the highest hypopnea index and prevalence of atrial fibrillation. Moreover, patients in Cluster 1 had significantly higher augmentation index than those in Cluster 2. Cluster 2 patients (N=80, 34.5%) were of older age, predominantly male, with the highest prevalence of depression, the lowest prevalence of hypertension and had the most normal body mass index (BMI). Additionally, Cluster 2 had less nocturnal hypoxia as compared to Cluster 3. Cluster 3 (n=68, 29.3%) was the youngest in age, predominantly male, with the highest BMI, cumulative risk score, and prevalence of dyslipidemia of the three clusters.

CONCLUSION

Post-stroke OSA can be categorized into three clinical phenotypes. Patients in Clusters 1 and 3 both had elevated cardiovascular risk and treatment can be based on their distinct characteristics. Patients in Cluster 2 had relatively lower risk of cardiovascular events and the benefits of OSA treatment requires further study.

Arterial Stiffness Predicts General Anesthesia-Induced Vasopressor-Resistant Hypotension in Patients Taking Angiotensin-Converting Enzyme Inhibitors

OBJECTIVES

Patients chronically treated with angiotensin-converting enzyme inhibitors (ACEIs) may develop hypotension after induction of general anesthesia. A fraction of these patients are resistant to therapeutic doses of vasopressors, which poses serious concerns for hemodynamic management. The authors hypothesized that the patients who develop refractory hypotension, compared with those who do not, show lower central arterial stiffness due to the profound effect of ACEIs.

DESIGN

Prospective observational study.

SETTING

Single tertiary center.

INTERVENTIONS

Fifty surgical patients chronically treated with ACEIs were enrolled. Prior to surgery, all the patients had central arterial stiffness assessment measured by carotid-femoral pulse-wave velocity. Patients were categorized into 2 groups according to the systolic blood pressure response during the first 10 minutes after induction of general anesthesia: a vasopressor-resistant hypotension group requiring more than 200 µg phenylephrine, or a control group requiring no more than 200 µg of phenylephrine to maintain systolic blood pressure above 90 mmHg during the study period.

MEASUREMENTS AND MAIN RESULTS

Carotid-femoral pulse-wave velocity was significantly lower in the vasopressor-resistant hypotension group compared to the control group (7.6 [7.2-8.3] m/s v 9.9 [8.7-12.0] m/s, p = 0.001 [Hodges-Lehman median difference 2.2, 95% confidence interval = 1.1-4.4]).

CONCLUSION

These findings suggested that preoperative measurement of carotid-femoral pulse-wave velocity in patients chronically treated with ACEIs could help identify patients at increased risk of developing hypotension refractory to vasopressors after induction of general anesthesia.

Increased augmentation index in patients with Ehlers-Danlos syndrome

Background

Ehlers-Danlos Syndrome (EDS) comprises a heterogeneous group of diseases characterized by joint hypermobility, connective tissue friability, and vascular fragility. Reliable prognostic factors predicting vascular disease progression (e.g. arterial aneurysms, dissections, and ruptures) in EDS patients are still missing. Recently, applanation tonometry derived augmentation index (AIx), an indirect marker of arterial stiffness, has shown to be positively associated with progression of aortic disease in Marfan syndrome. In this study, we assessed aortic AIx in patients with EDS and matched healthy controls.

Methods

We performed noninvasive applanation tonometry in 61 adults with EDS (43 women and 18 men aged 39.3 ± 14.6 years) and 61 age-, gender-, height-, and weight-matched healthy controls. Radial artery pulse waveforms were recorded and analyzed using the SphygmoCor System (AtCor Medical, Sydney, NSW, Australia). Calculated AIx was adjusted to a heart rate of 75/min. Groups were compared and association between AIx and EDS was determined by univariate and multivariate regression analysis.

Results

EDS patients were categorized in classical type EDS (34%), hypermobile type EDS (43%), vascular type EDS (5%), or remained unassignable (18%) due to overlapping features. EDS patients showed a significantly increased aortic AIx compared to healthy controls (22.8% ± 10.1 vs 14.8% ± 14.0, p < 0.001). EDS showed a positive association with AIx; independent of age, sex, height, blood pressure, medication, and pack years of smoking.

Conclusions

Patients with EDS showed elevated AIx, indicating increased arterial stiffness when compared to healthy controls. Further investigations are needed in order to assess the prognostic value of increased AIx for cardiovascular outcomes in patients with EDS.

Hemodynamic Mechanism of the Age-Related Increase in Pulse Pressure in Women

Supplemental Digital Content is available in the text.

We examined the influence of arterial stiffening and ventricular ejection dynamics on the age-related increase in central pulse pressure. A total of 2033 women aged 18 to 91 years from the Twins UK cohort were studied. Aortic flow and central blood pressure were measured by Doppler sonography and carotid tonometry, respectively. Measured values of central pulse pressure were compared with values predicted from aortic pulse wave velocity and ventricular ejection characteristics. Central pulse pressure at the first shoulder (P1) increased with age from 29.2±8.0 in those <40 years to 44.2±13.8 mm Hg in those >70 years (means±SD; P<0.001), an increase explained almost entirely by the concomitant increase in aortic pulse wave velocity. Pulse pressure, at the second pressure peak (P2, usually equal to peak central pulse pressure) increased to a greater extent with age: from 29.1±7.8 mm Hg for those <40 years to 60.2±20.5 mm Hg for those >70 years (P<0.001). The ratio of P2/P1 closely mirrored the ratio of ejection volume to ejection velocity at corresponding time points, and the proportionately greater increase in P2 compared with P1 was explained by increased ventricular ejection up to the time of P2. This increased from 52.5±13.1 to 59.3±17.8 mL (P<0.001) in parallel with an age-related increase in stroke volume and body mass index. These results suggest that the age-related change in central pulse wave morphology is driven mainly by an increase in arterial stiffening and altered pattern of ventricular ejection.

Current status and therapeutic considerations of hypertension in the elderly

As the prevalence of hypertension in the elderly population is increasing, information regarding the characteristics, optimal blood pressure targets, and special considerations for elderly hypertensive patients is needed to improve clinical outcomes. Various factors should be considered when managing hypertension in elderly patients, and there are many controversial issues and conflicting results related to the optimal treatment of hypertension in the elderly. In this review, we provide an overview of the epidemiology and characteristics of elderly hypertensive patients and discuss the optimal treatment of hypertension in elderly people.

Impact of extreme prematurity or extreme low birth weight on young adult health and well-being: the Victorian Infant Collaborative Study (VICS) 1991-1992 Longitudinal Cohort study protocol

INTRODUCTION

Infants born extremely preterm (EP, <28 weeks' gestation) or with extremely low birth weight (ELBW,<1000 g) in the era when surfactant has been available clinically are at high risk of health and developmental problems in childhood and adolescence. However, how their health and well-being may be affected in adulthood is not well known. This study aims to compare between EP/ELBW and normal birthweight (NBW) controls: (1) physical health, mental health and socioemotional functioning at 25 years of age and (2) trajectories of these outcomes from childhood to adulthood. In addition, this study aims to identify risk factors in pregnancy, infancy, childhood and adolescence for poor physical health and well-being in EP/ELBW young adults.

METHODS AND ANALYSIS

The Victorian Infant Collaborative Study (VICS) is a prospective geographical cohort of all EP/ELBW survivors to 18 years of age born in the State of Victoria, Australia, from 1 January 1991 to 31 December 1992 (n=297) and contemporaneous term-born/NBW controls (n=262). Participants were recruited at birth and followed up at 2, 5, 8 and 18 years. This 25-year follow-up includes assessments of physical health (cardiovascular, respiratory and musculoskeletal), mental health and socioemotional functioning. Outcomes will be compared between the birth groups using linear and logistic regression, fitted using generalised estimating equations (GEEs). Trajectories of health outcomes from early childhood will be compared between the birth groups using linear mixed-effects models. Risk factors for adult outcomes will be assessed using linear and logistic regression (fitted using GEEs).

ETHICS AND DISSEMINATION

This study was approved by the Human Research Ethics Committees of the Royal Women's Hospital, Mercy Hospital for Women, Monash Medical Centre and the Royal Children's Hospital, Melbourne. Study outcomes will be disseminated through conference presentations, peer-reviewed publications, the internet and social media.

Evaluation of cardiac output variations with the peripheral pulse pressure to mean arterial pressure ratio

Cardiac output (CO) optimisation during surgery reduces post-operative morbidity. Various methods based on pulse pressure analysis have been developed to overcome difficulties to measure accurate CO variations in standard anaesthetic settings. Several of these methods include, among other parameters, the ratio of pulse pressure to mean arterial pressure (PP/MAP). The aim of this study was to evaluate whether the ratio of radial pulse pressure to mean arterial pressure (ΔPPrad/MAP) could track CO variations (ΔCO) induced by various therapeutic interventions such as fluid infusions and vasopressors boluses [phenylephrine (PE), norepinephrine (NA) or ephedrine (EP)] in the operating room. Trans-oesophageal Doppler signal and pressure waveforms were recorded in patients undergoing neurosurgery. CO and PPrad/MAP were recorded before and after fluid challenges, PE, NA and EP bolus infusions as medically required during their anaesthesia. One hundred and three patients (mean age: 52 ± 12 years old, 38 men) have been included with a total of 636 sets of measurement. During fluids challenges (n = 188), a positive correlation was found between ΔPPrad/MAP and ΔCO (r = 0.22, p = 0.003). After PE (n = 256) and NA (n = 121) boluses, ΔPPrad/MAP positively tracked ΔCO (r = 0.53 and 0.41 respectively, p < 0.001). By contrast, there was no relation between ΔPPrad/MAP and ΔCO after EP boluses (r = 0.10, p = 0.39). ΔPPrad/MAP tracked ΔCO variations during PE and NA vasopressor challenges. However, after positive fluid challenge or EP boluses, ΔPPrad/MAP was not as performant to track ΔCO which could make the use of this ratio difficult in current clinical practice.

Central Blood Pressure Parameters Correlate with Cardiac Structure and Function in Healthy Chinese Individuals without Cardiovascular Disease

PURPOSE

To explore the relationship between central blood pressure (BP) parameters and cardiac structure and function parameters in healthy individuals.

METHODS

Four hundred Chinese participants with no overt cardiovascular disease participated in this study. One hundred and seventy-one participants (42.8%) were male and the mean age was 60 years. Central BP was measured with the SphygmoCor system. Cardiac structure and function were assessed by echocardiography.

RESULTS

We showed a significant association of left atrial volume and left ventricular mass index (LVMI) with brachial and central systolic BP (SBP) and pulse pressure (PP; r = 0.189-0.0.39, p < 0.001). Left ventricular diastolic function and the E/A ratio were significantly associated with brachial and central BP (r = 0.228-0.469, p < 0.001). Multivariate regression analysis revealed that central SBP and PP were independently correlated with LVMI after normalization for age and other confounding variables (sex, body mass index, smoking, and alcohol intake, and the levels of triglycerides, high-density lipoprotein, low-density lipoprotein, creatinine, uric acid, fasting blood glucose, log C-reactive protein, and fibrinogen. However, only central SBP was found to be independently correlated with the E/A ratio.

CONCLUSIONS

Cardiac structure and diastolic function were associated with brachial and central BP. However, after normalization, cardiac structure parameters were independently correlated with central SBP and PP. Diastolic function was the only cardiac function parameter that correlated with central SBP.

High-Intensity Interval Cycling Exercise on Wave Reflection and Pulse Wave Velocity

Kingsley, JD, Tai, YL, Vaughan, J, and Mayo, X. High-intensity interval cycling exercise on wave reflection and pulse wave velocity. J Strength Cond Res 31(5): 1313-1320, 2017-The purpose of this study was to assess the effects of high-intensity exercise on wave reflection and aortic stiffness. Nine young, healthy men (mean ± SD: age: 22 ± 2 years) participated in the study. The high-intensity interval cycling exercise consisted of 3 sets of Wingate Anaerobic Tests (WATs) with 7.5% of bodyweight as resistance and 2 minutes of rest between each set. Measurements were taken at rest and 1 minute after completion of the WATs. Brachial and aortic blood pressures, as well as wave reflection characteristics, were measured through pulse wave analysis. Aortic stiffness was assessed through carotid-femoral pulse wave velocity (cfPWV). A repeated-measures analysis of variance was used to investigate the effects of the WATs on blood pressure and vascular function across time. There was no change in brachial or aortic systolic pressure from rest to recovery. There was a significant (p ≤ 0.05) decrease in brachial diastolic pressure (rest: 73 ± 6 mm Hg; recovery: 67 ± 9 mm Hg) and aortic diastolic pressure (rest: 75 ± 6 mm Hg; recovery: 70 ± 9 mm Hg) from rest to recovery. In addition, there was no significant change in the augmentation index (rest: 111.4 ± 6.5%; recovery: 109.8 ± 5.8%, p = 0.65) from rest to recovery. However, there was a significant (p ≤ 0.05) increase in the augmentation index normalized at 75 b·min (rest: 3.29 ± 9.82; recovery 21.21 ± 10.87) during recovery compared with rest. There was no change in cfPWV (rest: 5.3 ± 0.8 m·s; recovery: 5.7 ± 0.5m·s; p = 0.09) in response to the WAT. These data demonstrate that high-intensity interval cycling exercise with short rest periods has a nonsignificant effect on vascular function.

Impact of Continuous Positive Airway Pressure on Left Ventricular Systolic Loading and Coronary Flow Reserve in Healthy Young Men

BACKGROUND

Increased augmentation index (AIx) is accompanied by an elevated cardiovascular risk. A reduction of AIx is known for long-term continuous positive airway pressure (CPAP) therapy. We hypothesised that acute preload and left ventricular workload effects AIx and subendocardial viability ratio (SEVR) as a marker of coronary flow reserve.

METHODS

Increased augmentation index and central blood pressure parameters were measured by radial artery tonometry in 17 healthy men (32/±6years) at rest and during CPAP ventilation at pressures of 5, 10mbar and after recovery. In a subset of seven individuals, haemodynamic parameters and autonomic function were additionally examined using combined impedance cardiography and continuous noninvasive blood pressure monitoring.

RESULTS

Continuous positive airway pressure reduced heart rate corrected (AIx@75) (-2.8±8.1 [rest] to -10.7±11.3 [5mbar], p<0.01, to -12.2±10.5% [10mbar], p<0.01) and systolic time integral as a marker of left ventricular workload (2115±231 [rest] to 1978±290 [5mbar], p=0.02 to 1940±218 [10mbar], p<0.01 to 2013±241mmHg/s per min [recovery], p=0.03), while central systolic pressure did not change during CPAP. Total Peripheral Resistance Index increased reaching level of significance at 10mbar CPAP condition (1701±300 [rest] to 1850±301dyn*s*m²/cm⁵ [10mbar], p=0.04). There was a reversible increase of SEVR under CPAP conditions.

CONCLUSIONS

Continuous positive airway pressure ventilation acutely reduces AIx, heart rate and left ventricular workload in healthy young men. These effects seem to be mediated by left ventricular filling pressure, workload and reflection wave. Furthermore, we found an increase of subendocardial viability ratio as an indication for a rising coronary flow reserve by CPAP.

Understanding the physiology of mindfulness: aortic hemodynamics and heart rate variability

Data were collected to examine autonomic and hemodynamic cardiovascular modulation underlying mindfulness from two independent samples. An initial sample (N = 185) underwent laboratory assessments of central aortic blood pressure and myocardial functioning to investigated the association between mindfulness and cardiac functioning. Controlling for religiosity, mindfulness demonstrated a strong negative relationship with myocardial oxygen consumption and left ventricular work but not heart rate or blood pressure. A second sample (N = 124) underwent a brief (15 min) mindfulness inducing intervention to examine the influence of mindfulness on cardiovascular autonomic modulation via blood pressure variability and heart rate variability. The intervention had a strong positive effect on cardiovascular modulation by decreasing cardiac sympathovagal tone, vasomotor tone, vascular resistance and ventricular workload. This research establishes a link between mindfulness and cardiovascular functioning via correlational and experimental methodologies in samples of mostly female undergraduates. Future directions for research are outlined.

Obstructive sleep apnea is independently associated with arterial stiffness in ischemic stroke patients

Obstructive sleep apnea (OSA) is a predictor of all-cause mortality and recurrent vascular events following stroke. However, few studies have investigated the pathophysiology of OSA in ischemic stroke patients. Whether OSA independently increases arterial stiffness in ischemic stroke patients is determined by measuring the carotid-femoral pulse wave velocity (PWV) and via the central augmentation index (AIx). This cross-sectional study consecutively recruited 127 subacute ischemic stroke patients who were admitted to a teaching hospital for inpatient rehabilitation (median age, 61.3 years; IQR 53.6-72.7 years). Vascular measurements were performed following polysomnography. Multivariate linear regression analysis was performed to determine the relationship between arterial stiffness and OSA. Patients with severe OSA were significantly older, had significantly higher PWV and mean blood pressure, and a significantly higher risk of hypertension than those with non-severe OSA. The significant bivariate correlation between AIx@75 and the desaturation index (DI) (Spearman's ρ = 0.182, P = 0.040) became insignificant by multivariate regression analysis. The PWV was significantly correlated with the apnea-hypopnea index (AHI) (Pearson's r = 0.350, P = 0.000) and DI (Spearman's ρ = 0.347, P = 0.000). The correlation between PWV and OSA parameters, including presence of severe OSA, AHI and DI, remained significant by multivariate regression analysis with age, systolic blood pressure, diabetic mellitus, hypertension and the Barthel index as potential confounders. Arterial stiffness is independently associated with OSA, and PWV can be applied as an intermediate endpoint in further intervention trials of ischemic stroke patients with OSA.

A feasibility study of the association of exposure to biomass smoke with vascular function, inflammation, and cellular aging

BACKGROUND

Biomass smoke at higher concentrations is associated with respiratory symptoms and, after years of exposure, increased risk of respiratory disorders in adults, but its effects on cardiovascular diseases are not well characterized, particularly compared with other pollution sources like tobacco smoke or traffic.

METHODS

We conducted a cross-sectional study and enrolled 25 women living in rural Sichuan, China. We measured integrated 24-h personal exposure to fine particulate matter (PM2.5) and black carbon, and measured PM2.5 and black carbon in their kitchens. We assessed participants' brachial and central blood pressure and arterial stiffness using pulse wave analysis, and analyzed dried blood spot and buccal cell samples for C-reactive protein and relative telomere length. We also evaluated the difference in these physiological and biomarker measures between individuals with high (≥median) versus low (<median) PM2.5 exposure using multivariate regression.

RESULTS

Geometric mean 24-h PM2.5 and black carbon exposures were 61 µg/m(3) (95% CI: 48, 78) and 3.2 µg/m(3) (95% CI: 2.3, 4.5), respectively. Average kitchen PM2.5 and black carbon concentrations were only moderately correlated with personal exposures (PM2.5: r=0.41; black carbon: r=0.63), although they had similar means. Women in the high and low exposure groups were similar in age, obesity, socioeconomic status, salt intake, and physical activity. Women in the high PM2.5 exposure group had higher mean brachial systolic blood pressure (SBP; difference=4.6 mmHg, 95% CI -7.8, 16.9), central SBP (difference=3.1 mmHg, 95% CI: -8.4, 14.5), central pulse pressure (difference=4.1 mmHg; 95% CI: -4.2, 12.4), and augmentation index (difference=2.8%, 95% CI: -1.6, 7.2). High exposed women had 43% shorter telomere length (95% CI: -113, 28) than that of women in the low exposure group. There were no differences in pulse wave velocity or C-reactive protein between the two exposure groups. None of the results was statistically significant.

CONCLUSIONS

Our results suggest that it is feasible to measure markers of vascular function and biomarkers of inflammation and oxidative stress in field studies of biomass smoke. Although many of the associations were in the expected direction, larger studies would be needed to establish the effects.

Impact of acute whole-body cold exposure with concurrent isometric handgrip exercise on aortic pressure waveform characteristics

PURPOSE

Adverse cardiovascular events are more prevalent during winter and in people that exercise/work in cold temperatures. Since pulse wave analysis indices, aortic systolic blood pressure (ASBP), augmentation index (AIx), and wasted left ventricular pressure energy (ΔE w), are stronger predictors of cardiovascular events and myocardial performance than brachial blood pressure (BP), we sought to evaluate the aortic hemodynamic responses during cold exposure with concurrent isometric handgrip exercise (IHG).

METHODS

In a crossover randomized fashion, 20 healthy normotensive men (22.1 ± 2 years) were evaluated, by means of radial applanation tonometry, inside an environmental chamber in the supine position at cold (4 °C) and temperate (24 °C) conditions. Following a 30-min equilibration period, measurements were performed during pre-exercise baseline (REST), in the last 90 s of a 3-min IHG at 30% maximal voluntary contraction, and 3 min immediately after the finalization of IHG bout (recovery, REC).

RESULTS

At REST, brachial systolic BP (BSBP) (12 ± 2 mmHg; P < 0.01), ASBP (14 ± 3 mmHg; P < 0.01), AIx (11 ± 3%; P < 0.05), and ΔE w (737 ± 128 dynes s/cm(2); P < 0.01) were higher in 4 °C compared to 24 °C trial. Compared to REST, IHG significantly increased (P < 0.01) BSBP, ASBP, AIx, and ΔEw, while BSBP and ASBP remained elevated during REC (P < 0.01). Compared to REST and temperate, AIx (11 ± 3%) and ΔE w (793 ± 145 dynes s/cm(2); P < 0.01) were higher during IHG and cold, while BSBP and ASBP were elevated during REC and cold. AIx and ΔE w returned to REST values in both trials, but AIx (11 ± 4%; P < 0.05) and ΔE w (656 ± 132 dynes s/cm(2); P < 0.05) were higher in the cold.

CONCLUSIONS

Cold exposure with concurrent IHG induces a significant increase in aortic hemodynamic markers, which may evoke adverse cardiovascular events.

Left ventricular mass progression despite stable blood pressure and kidney function in stage 3 chronic kidney disease

BACKGROUND/AIMS

Progressive chronic kidney disease (CKD) is associated with worsening cardiovascular (CV) risk not explained by traditional risk factors. Left ventricular (LV) hypertrophy (LVH) is an important CV risk factor, but its progression has not been documented in early CKD. We explored whether progression of LVH in early CKD would occur despite stable kidney function.

METHODS

We conducted a post hoc analysis of a 12-month study of lanthanum carbonate in stage 3 CKD, which included longitudinal assessments of CV biomarkers. Primary outcome for the analysis was the change in LV mass (LVM) indexed to height in meters(2.7) (LVM/Ht(2.7)). Secondary outcomes were changes in blood pressure (BP), pulse-wave velocity, LV systolic/diastolic function, fibroblast growth factor 23 (FGF23), klotho, and estimated glomerular filtration rate (eGFR).

RESULTS

Thirty-one of 38 original subjects had sufficient data for analysis. LVM/Ht(2.7) increased (47 ± 13 vs. 53 ± 13 g/m(2.7), p = 0.006) over 12 months despite stable BP, stable eGFR and normal LV systolic function. Vascular stiffness and LV diastolic dysfunction persisted throughout the study. Klotho levels decreased (748 ± 289 to 536 ± 410 pg/ml, p = 0.03) but were unrelated to changes in LVM/Ht(2.7). The change in FGF23/klotho ratio was strongly correlated with changes in LVM/Ht(2.7) (r2 = 0.582, p = 0.03).

CONCLUSION

Subjects with stage 3 CKD exhibited increasing LVM, persistent LV diastolic dysfunction and vascular stiffness despite stable kidney function, BP and LV systolic function. Abnormal FGF23 signaling due to reduced klotho expression may be associated with increasing LVM.

Association of EZSCAN values with arterial stiffness in individuals without diabetes or cardiovascular disease

Background

The EZSCAN test was recently developed to screen for early dysglycemia through an assessment of sudomotor function. Given the associations of dysglycemia and autonomic dysfunction with the development of arterial stiffness, EZSCAN may also detect early arterial stiffness. The aim of this study was to investigate the association of EZSCAN with arterial stiffness across blood glucose levels.

Methodology and Principal Findings

A total of 5532 participants without diabetes or established cardiovascular disease were evaluated with EZSCAN. Their central systolic blood pressure (cSBP), brachial-ankle pulse wave velocity (baPWV), and ankle-brachial index (ABI) were also measured. Multivariate linear regression analyses were used to assess the association between the EZSCAN value and the cSBP, baPWV, and ABI measurements in all of the participants, with additional subgroup analysis that separated participants into a normal glucose tolerance (NGT) group and an impaired glucose regulation (IGR) group. The frequency of the IGRs increased with quartiles of the EZSCAN value (P for trend <0.0001). The levels of cSBP and baPWV increased while the levels of ABI decreased across quartiles of EZSCAN value in both NGT and IGR individuals (P for trend <0.0001 for all). In multivariable analyses, the EZSCAN value was positively associated with cSBP (log-transformed beta = 8.20, P<0.0001) and baPWV (log-transformed beta = 1.82, P<0.0001) but inversely associated with ABI (log-transformed beta = −0.043, P<0.0001) and was independent of conventional factors. Further adjustment for fasting and postprandial glucoses did not attenuate the associations. The results were also unchanged when stratified by IGR.

Conclusions and Significance

The EZSCAN results were associated with arterial stiffness independent of conventional factors, blood glucose levels, and glucose tolerance status, suggesting a probable link between the EZSCAN value and arterial stiffness through autonomic dysfunction. The EZSCAN test may help us detect the development of arterial stiffness in high risk individuals to prevent unfavorable cardiovascular events.

Associations between short-term changes in air pollution and correlates of arterial stiffness: The Veterans Affairs Normative Aging Study, 2007-2011

We investigated associations between short-term exposure to air pollution and central augmentation index and augmentation pressure, correlates of arterial stiffness, in a cohort of elderly men in the Boston, Massachusetts, metropolitan area. This longitudinal analysis included 370 participants from the Veterans Affairs Normative Aging Study with up to 2 visits between 2007 and 2011 (n = 445). Augmentation index (as %) and augmentation pressure (in mmHg) were measured at each visit by using radial artery applanation tonometry for pulse wave analysis and modeled in a mixed effects regression model as continuous functions of moving averages of air pollution exposures (over 4 hours and 1, 3, 7, and 14 days). The results suggest that short-term changes in air pollution were associated with augmentation index and augmentation pressure at several moving averages. Interquartile range (IQR) increases in 3-day average exposure to particles with aerodynamic diameter less than 2.5 μm (3.6-μg/m(3) IQR increase) and sulfate (1.4-μg/m(3) IQR increase) and 1-day average exposure to particle number counts (8,741-counts/cm(3) IQR increase) were associated with augmentation index values that were 0.8% (95% confidence interval (CI): 0.2, 1.4), 0.6% (95% CI: 0.1, 1.2), and 1.7% (95% CI: 0.4, 2.9) higher, respectively. Overall, the findings were similar for augmentation pressure. The findings support the hypothesis that exposure to air pollution may affect vascular function.

School burnout and cardiovascular functioning in young adult males: a hemodynamic perspective

This study investigated aortic and brachial hemodynamic functioning that may link school burnout to cardiovascular risk factors. Methodological improvements from previous research were implemented including (1) statistical control of depressive and anxiety symptoms (2) resting, stress-induced and cardiac recovery condition comparisons and (3) use of pulse wave analysis. Forty undergraduate young adult males completed self-report measures of school burnout, trait anxiety and depressive symptoms. Participants then completed a protocol consisting of a 10-min seated rest, 5-min baseline (BASE), 3-min cold pressor test (CPT) and a 3-min recovery period (REC). Indices of brachial and aortic hemodynamics were obtained by means of pulse wave analysis via applanation tonometry. Controlling for anxiety and depressive symptoms, planned contrasts identified no differences in cardiovascular parameters at BASE between participants in burnout and non-burnout groups. However, negative changes in hemodynamic indices occurred in burnout participants at CPT and REC as evidenced by increased aortic and brachial systolic and diastolic blood pressures, increased left ventricular work and increased myocardial oxygen consumption. Findings suggest that school burnout symptoms are associated with cardiac hyperactivity during conditions of cardiac stress and recovery and therefore may be associated with the early manifestations of cardiovascular disease. Future studies are suggested to reveal underlying autonomic mechanisms explaining hemodynamics functioning in individuals with school burnout symptomatology.

Effects of phosphate binder therapy on vascular stiffness in early-stage chronic kidney disease

BACKGROUND/AIMS

Cardiovascular disease (CVD) is increased in chronic kidney disease (CKD), and contributed to by the CKD-mineral bone disorder (CKD-MBD). CKD-MBD begins in early CKD and its vascular manifestations begin with vascular stiffness proceeding to increased carotid artery intima-media thickness (cIMT) and vascular calcification (VC). Phosphorus is associated with this progression and is considered a CVD risk factor in CKD. We hypothesized that modifying phosphorus balance with lanthanum carbonate (LaCO3) in early CKD would not produce hypophosphatemia and may affect vascular manifestations of CKD-MBD.

METHODS

We randomized 38 subjects with normophosphatemic stage 3 CKD to a fixed dose of LaCO3 or matching placebo without adjusting dietary phosphorus in a 12-month randomized, double-blind, pilot and feasibility study. The primary outcome was the change in serum phosphorus. Secondary outcomes were changes in measures of phosphate homeostasis and vascular stiffness assessed by carotid-femoral pulse wave velocity (PWV), cIMT and VC over 12 months.

RESULTS

There were no statistically significant differences between LaCO3 and placebo with respect to the change in serum phosphorus, urinary phosphorus, tubular reabsorption of phosphorus, PWV, cIMT, or VC. Biomarkers of the early CKD-MBD such as plasma fibroblast growth factor-23, Dickkopf-related protein 1 (DKK1), and sclerostin were increased 2- to 3-fold at baseline, but were not affected by LaCO3.

CONCLUSION

Twelve months of LaCO3 had no effect on serum phosphorus and did not alter phosphate homeostasis, PWV, cIMT, VC, or biomarkers of CKD-MBD.

Racial differences in arterial stiffness and microcirculatory function between Black and White Americans

BACKGROUND

Compared with whites, black Americans suffer from a disproportionate burden of cardiovascular disease (CVD). We hypothesized that racial differences in the prevalence of CVD could be attributed, in part, to impaired vascular function in blacks after adjustment for differences in risk factor burden.

METHODS AND RESULTS

We assessed vascular function in 385 black and 470 white subjects (mean age, 48±11 years; 45% male). Using digital pulse amplitude tonometry (EndoPAT) we estimated the reactive hyperemia index (RHI), a measure of microvascular endothelial function, and peripheral augmentation index (PAT-AIx). Central augmentation index (C-AIx) and pulse-wave velocity (PWV) were measured as indices of wave reflections and arterial stiffness, respectively, using applanation tonometry (Sphygmocor). Compared with whites, blacks had lower RHI (2.1±0.6 versus 2.3±0.6, P<0.001), greater arterial wave reflections assessed as both PAT-AIx (20.4±21.5 versus 17.0±22.4, P=0.01) and CAIx (20.8±12.3 versus 17.5±13.3, P=0.001), and greater arterial stiffness, measured as PWV (7.4±1.6 versus 7.1±1.6 m/s, P=0.001). After adjustment for traditional CVD risk factors, black race remained a significant predictor of lower RHI and higher PAT-AIx and CAIx (all P<0.001) in all subjects and of higher PWV in men (P=0.01). Furthermore, these associations persisted in a subgroup analysis of "healthy" individuals free of CVD risk factors.

CONCLUSION

Black race is associated with impaired microvascular vasodilatory function, and greater large arterial wave reflections and stiffness. Because impairment in these vascular indices may be associated with worse long-term outcomes, they may represent underlying mechanisms for the increased CVD risk in blacks.

Carotid intima-media thickness is associated with cognitive deficiency in hypertensive patients with elevated central systolic blood pressure

Background

The role of hypertension in the loss of cognitive function is controversial. Relationships between hypertension and increases in cerebral vascular resistance, diffused lesions and multiple lacunar infarcts of the white matter are well known. Thus, the objectives of this study were: to evaluate the relationship between hypertension and cognitive dysfunction (CD), identify risk factors and determine the association between early markers of vascular disease and CD in hypertensive individuals.

Methods

Two hundred individuals aged between 40 and 80 years old were evaluated in this cross-sectional prospective study. Fifty participants were controls (CT). The remaining 150 hypertensive patients were subdivided into two groups, those with CD (HCD) and those without CD (HNCD). All participants underwent clinical evaluations and biochemical blood tests were performed. CD was investigated using the Mini Mental State Examination (MMSE) following the guidelines for its use in Brazil. The impact of hypertension on the arterial bed was assessed by identifying and measuring changes in the intima-media thickness (IMT) by vascular ultrasonography of the carotid arteries and analyses of the central blood pressure and Augmentation Index by applanation tonometry of the radial artery.

Results

There were no significant differences in the total cholesterol, high-density lipoprotein cholesterol and triglycerides plasma concentrations between the three groups. The serum creatinine and estimated glomerular filtration rate were within normal ranges for all three groups. A significantly lower MMSE score was recorded for the HCD Group compared to the HNCD and CT Groups (p-value < 0.05).

The IMT was significantly different between the HNCD and HCD Groups (p-value = 0.0124). A significant difference in the IMT was also observed between hypertensive patients and the CT Group (p-value < 0.0001). Age, low-density cholesterol, high-density cholesterol, triglycerides and IMT increased the Odds Ratio for cognitive dysfunction.

The central systolic pressure was significantly higher in the HCD and HNCD Groups compared to CT Group (p-value < 0.0001).

Conclusions

Hypertensive patients with CD have changes in the vascular morphology characterized by an increased carotid IMT, enhanced atherosclerotic lipid profile and impaired hemodynamic functional manifested by elevated central systolic blood pressure.

Comparison of arterial stiffness indices measured by the Colins and SphygmoCor systems

Arterial stiffness is a known independent predictor of cardiovascular mortality. The Colins system is an easy device and has gained widespread use, but the cutoff value for high-risk central arterial stiffness is not well established. We investigated the correlation between arterial stiffness measured by the Colins system with conventional measurements from the SphygmoCor system. Arterial pulse wave velocity (PWV) and augmentation indices (AIs) were measured on a single visit using two different devices in 948 patients with hypertension or coronary artery disease. Strong positive correlations were observed for PWV values measured by the SphygmoCor and Colins systems. The Colins system measurements accurately predicted high-risk central arterial stiffness, defined as carotid-femoral PWV≥12 m s(-1), with an area under the receiver-operating characteristic curve (AUC) of 0.884 (heart-femoral PWV, hfPWV) and 0.830 (brachial-ankle PWV, baPWV) in the training set (N=664). The cutoff values, 11.18 (hfPWV) and 16.17 m s(-1) (baPWV), showed good discrimination in the validation set (N=284), with sensitivity of 83.3 (hfPWV) and 76.0% (baPWV), and specificity of 74.9 (hfPWV) and 82.6% (baPWV). The SphygmoCor and Colins AI systems also showed moderate positive correlation. The Colins AI system better predicted high-risk central pulse pressure as defined by pulse pressure≥50 mm Hg (AUC: Colins, 0.765; SphygmoCor, 0.692; P=0.011). Arterial stiffness measured by the Colins system showed strong positive correlation and agreement with the SphygmoCor system measurement. Cutoff values for high-risk central arterial stiffness in the Colins system need further validation in a prospective study.

Assessment of central haemomodynamics from a brachial cuff in a community setting

BACKGROUND

Large artery stiffening and wave reflections are independent predictors of adverse events. To date, their assessment has been limited to specialised techniques and settings. A new, more practical method allowing assessment of central blood pressure from waveforms recorded using a conventional automated oscillometric monitor has recently been validated in laboratory settings. However, the feasibility of this method in a community based setting has not been assessed.

METHODS

One-off peripheral and central haemodynamic (systolic and diastolic blood pressure (BP) and pulse pressure) and wave reflection parameters (augmentation pressure (AP) and index, AIx) were obtained from 1,903 volunteers in an Austrian community setting using a transfer-function like method (ARCSolver algorithm) and from waveforms recorded with a regular oscillometric cuff. We assessed these parameters for known differences and associations according to gender and age deciles from <30 years to ≥80 years in the whole population and a subset with a systolic BP < 140 mmHg.

RESULTS

We obtained 1,793 measures of peripheral and central BP, PP and augmentation parameters. Age and gender associations with central haemodynamic and augmentation parameters reflected those previously established from reference standard non-invasive techniques under specialised settings. Findings were the same for patients with a systolic BP below 140 mmHg (i.e. normotensive). Lower values for AIx in the current study are possibly due to differences in sampling rates, detection frequency and/or averaging procedures and to lower numbers of volunteers in younger age groups.

CONCLUSION

A novel transfer-function like algorithm, using brachial cuff-based waveform recordings, provides robust and feasible estimates of central systolic pressure and augmentation in community-based settings.

Arterial pressure profile in patients with cirrhosis: Fourier analysis of arterial pulse in relation to pressure level, stroke volume, and severity of disease: on the reduction of afterload in the hyperdynamic syndrome

OBJECTIVE

Patients with cirrhosis have cardiovascular dysfunction and altered mechanical properties of large and small arteries. This study was undertaken in order to analyze the arterial pressure curve in relation to mean arterial pressure level, stroke volume, and severity of liver disease.

MATERIALS AND METHODS

Forty-one patients with cirrhosis (Child-Turcotte classes A/B/C = 13/15/13) were studied during a hemodynamic investigation of portal hypertension. Fifteen patients without liver disease served as controls. We applied fast Fourier analysis to quantify the pressure components of the arterial curve, the harmonic Fourier coefficients (HFC).

RESULTS

Mean arterial pressure was significantly reduced (91 vs. 98 mmHg, p < 0.001) and stroke volume was significantly increased (94 vs. 78 ml, p < 0.001) in patients with cirrhosis versus controls. The HFC were significantly lower in patients with cirrhosis than in controls (-15 to -24%, p < 0.002), except for the fourth HFC, which was significantly increased (+28%, p < 0.02). In contrast to controls, which showed a highly significant effect of the level of arterial pressure on their HFC (p < 0.001), patients with cirrhosis did not show pressure or stroke volume dependence on their HFC, indicating an overall compliant and slow reflective arterial vascular bed. The initial rise in pulse pressure (dP/dt) was inversely related to the Child-Turcotte score (p < 0.05), and the HFC were borderline significantly related to this score (p = 0.07).

CONCLUSIONS

The arterial pulsation in cirrhosis is qualitatively changed with reduced pulse reflections, which may protect against manifest cardiac failure in patients with advanced cirrhosis.

Validation of the noninvasive assessment of central blood pressure by the SphygmoCor and Omron devices against the invasive catheter measurement

BACKGROUND

To investigate the accuracy of the SphygmoCor and Omron HEM9000-AI devices in the estimation of central blood pressure (BP) in comparison with the simultaneous invasive catheter measurement.

METHODS

The radial arterial pulse was sequentially recorded by the use of the Omron and SphygmoCor devices in 33 patients, with the calibration of the brachial oscillometric BP, to derive central BPs, which were also measured simultaneously with a catheter-based fluid-filled manometer system. The procedure was repeated three times to obtain 99 pairs of noninvasive and invasive measurements.

RESULTS

The noninvasive central systolic BP estimations were significantly (P < 0.001) associated with the invasive measurement at the ascending aorta, with a correlation coefficient of 0.91 and 0.90 for the SphygmoCor and Omron devices, respectively. However, both devices underestimated central systolic BP with a difference of -15 mm Hg (95% confidence interval (CI), -17 to -13 mm Hg, P < 0.001) for SphygmoCor and -2 mm Hg (95% CI, -4 to 0 mm Hg, P < 0.05) for Omron. In comparison with the invasive catheter measurement at the brachial artery, the oscillometric Omron device underestimated brachial systolic BP by -19 mm Hg (95% CI, -23 to -15 mm Hg, P < 0.001).

CONCLUSIONS

Both devices underestimated central systolic BP, with a larger deviation by SphygmoCor. Nonetheless, these noninvasive estimations of central BP closely correlate with the invasive measurements, and can still be properly used, on the condition that device specific diagnostic thresholds become available.

Augmentation index association with reactive hyperemia as assessed by peripheral arterial tonometry in hypertension

BACKGROUND

Augmentation pressure has emerged as a surrogate marker for cardiovascular disease, and endothelial dysfunction has been proposed as related factor. However, the relationship between augmentation pressure and digital endothelial function has not yet been well defined. We investigated the relationship between augmentation pressure and digital reactive hyperemia (RH) in patients with hypertension using peripheral arterial tonometry (PAT), which is regarded as being representative of endothelial function.

METHODS

One hundred hypertensive patients (64 males; mean age, 49 ± 12 years) without a history of taking antihypertensive medication were enrolled in this study.

RESULTS

The mean augmentation pressure and augmentation index (AIx) normalized for a heart rate of 75 beats/min (AIx75) were 15 ± 8 mm Hg and 26 ± 11%, respectively. The mean RH-PAT index and log transformed PAT ratio were 2.24 ± 0.55 and 0.62 ± 0.30. There was an inverse relationship between the RH-PAT index and age, male sex, and body mass index. The log transformed PAT ratio also showed inverse relationship with age and male sex. The RH-PAT index and the log transformed PAT ratio showed no relationship with augmentation pressure or AIx75. In a multiple linear regression analysis, age, height, and central systolic BP demonstrated an independent association with augmentation pressure and AIx75.

CONCLUSION

In patients with hypertension, the RH-PAT index determined using PAT was not associated with augmentation pressure or AIx75. Digital vascular function may be a less important factor for pressure augmentation in patients with hypertension.

Phase II trials in heart failure: the role of cardiovascular imaging

The development of new therapies for heart failure (HF), especially acute HF, has proven to be quite challenging; and therapies evaluated in HF have greatly outnumbered treatments that are eventually successful in obtaining regulatory approval. Thus, the development of therapies for HF remains a vexing problem for pharmaceutical and device companies, clinical trialists, and health care professionals. Nowhere is this more apparent than in the phase II HF clinical trial, in which the goal is to determine whether an investigational agent should move forward to a phase III trial. Recent advancements in noninvasive cardiovascular imaging have allowed a new era of comprehensive phenotyping of cardiac structure and function in phase II HF trials. Besides using imaging parameters to predict success of subsequent phase III outcome studies, it is essential to also use imaging in phase II HF trials in a way that increases understanding of drug or device mechanism. Determination of the patients who would benefit most from a particular drug or device could decrease heterogeneity of phase III trial participants and lead to more successful HF clinical trials. In this review, we outline advantages and disadvantages of imaging various aspects of cardiac structure and function that are potential targets for therapy in HF, compare and contrast imaging modalities, provide practical advice for the use of cardiovascular imaging in drug development, and conclude with some novel uses of cardiac imaging in phase II HF trials.

Impact of passive vibration on pressure pulse wave characteristics

The augmentation index (AIx), a marker of wave reflection, decreases following acute leg exercise. Passive vibration (PV) causes local vasodilation that may reduce AIx. This study investigated the effects of acute PV on wave reflection and aortic hemodynamics. In a crossover fashion 20 (M=9, F=11) healthy young (22±3 year) participants were randomized to 10 min PV or no vibration control (CON) trials. Subjects rested in the supine position with their legs over a vibration platform for the entire session. Radial waveforms were obtained by applanation tonometry before and after 3 min (Post-3) and 30 min (Post-30) of PV (∼5.37 G) or CON. No change in parameters was found at Post-3. We found significant time-by-trial interactions (P<0.01) at Post-30 for augmented pressure, AIx and second systolic peak pressure (P2), such that these parameters significantly (P<0.05) decreased (-2.3±3.0 mm Hg, -7.2±6.9% and -1.5±3.5 mm Hg, respectively) after PV but not after CON. These findings suggest that acute PV applied to the legs decreases AIx owing to a decrease in wave reflection magnitude (P2). Further research is warranted to evaluate the potential clinical application of PV in populations at an increased cardiovascular risk who are unable to perform conventional exercise.

Early Identification of Vascular Damage in Patients With Systemic Sclerosis

Vascular involvement in systemic sclerosis (SSc) plays a key role in the pathogenesis of fibrosis. We assessed arterial stiffness using a new echo-tracking technique in patients with SSc asymptomatic for cardiovascular diseases. We enrolled 22 patients (21 female, 63 ± 14 years) and 20 controls (12 female, 62 ± 3 years). Carotid intima-media thickness (IMT) was comparable between the 2 groups (1.1 ± 0.3 vs 1.0 ± 0.4 mm, P = ns), whereas the stiffness parameters were significantly increased in patients (β: 9.5 ± 4.2 vs 5.8 ± 1.1, P = .001; pulse wave velocity [PWV]: 6.5 ± 1.5 vs 5.2 ± 0.6 m/sec, P = .003). A correlation between stiffness parameters, anti-Scl-70 antibodies (β: r = .46, P = .03; PWV: r = .50, P = .02), and anticentromere antibodies (β: r = -.54, P = .020; PWV: r = -.53, P = .023) was found. Echo-tracking technique may be valuable in early identification of vascular involvement in patients with SSc.

Changes in pulse pressure following fluid loading: a comparison between aortic root (non-invasive tonometry) and femoral artery (invasive recordings)

PURPOSE

To document the relationship between stroke volume (SV) and pulse pressure (PP) recorded at the femoral and aortic sites during volume expansion (VE) in patients in shock. We hypothesized that non-invasively estimated aortic PP would exhibit the same ability as PP recorded invasively at the femoral level to track SV changes.

METHODS

Included in this prospective study were 56 ICU patients needing VE. Femoral PP (indwelling catheter), aortic PP (tonometry) and cardiac output (thermodilution) were recorded before and after VE. Responders were defined as patients who showed an increase in SV of ≥15% after VE.

RESULTS

Of the 56 included patients in shock, 39 (age 57 ± 14 years, SAPS II 46 ± 18) completed the study. At both sites, PP increased after VE in responders (n=17, mean SV increase 30 ± 15%) but not in non-responders. In the overall population, there was a positive relationship between VE-induced changes in SV and in PP at the femoral (r=0.60, p<0.001) and aortic (r=0.52, p<0.001) sites. Increases in femoral PP of ≥9% indicated SV increases of ≥15% with 82% sensitivity and 95% specificity. Increases in aortic PP of ≥4.5% indicated SV increases of ≥15% with 76% sensitivity and 82% specificity. Areas under the ROC curves indicated that aortic PP was not different from femoral PP for tracking changes in SV.

CONCLUSION

The ability of non-invasively estimated aortic PP to track fluid response was the same as that of invasively recorded femoral PP. This may have implications for non-invasive haemodynamic monitoring.

Differing effects of aging on central and peripheral blood pressures and pulse wave velocity: a direct intraarterial study

OBJECTIVES

There have been a few noninvasive studies showing the effect of aging on blood pressure (BP) and pulse wave velocity (PWV) in different arterial segments. The aim of this study was to evaluate the effect of aging on arterial hemodynamics in central and peripheral arteries using an invasive method.

METHODS

We observed 175 individuals undergoing coronary angiography. SBP and DBP were measured by pressure wave at the radial artery, abdominal aorta, and aortic arch. Aortic arch-abdominal aorta PWV (aoPWV) and aortic arch-radial artery PWV (arPWV) were also assessed by the foot-to-foot velocity method using a fluid-filled system.

RESULTS

SBP and pulse pressure were significantly positively correlated and DBP was significantly negatively correlated with age through the arterial tree in a multivariate analysis after adjusting for sex, coronary artery disease, diabetes, dyslipidemia, smoking status, and the use of antihypertensive agents. Pulse pressure, SBP, and DBP were significantly associated with age (ranked in order of association strength) at all studied arterial segments. Each central BP showed a consistently higher correlation with age than radial BP. aoPWV and arPWV were also significantly correlated with age, and this relationship was much stronger for aoPWV (r = 0.474, P < 0.001) than for arPWV (r = 0.224, P = 0.003).

CONCLUSION

The present invasive study suggests that aging has a greater effect on central rather than peripheral arterial hemodynamics. The central pulse pressure was the predominant BP affected by aging, which could be caused by the stronger relationship of aging with central arterial stiffness.

Differential effects of beta-adrenoreceptor antagonists on central and peripheral blood pressure at rest and during exercise

BACKGROUND

Differential effects of beta-adrenoreceptor antagonists (beta-ARB) on central and peripheral blood pressure may relate to change in heart rate and/or vasodilator tone and thus be exaggerated during exercise.

AIMS

To examine acute effects of selective and nonselective beta-ARB on central and peripheral blood pressure, cardiac output and peripheral vascular resistance during exercise.

METHODS

Healthy volunteers (n= 20, 18 men, 19-54 years) received propranolol 80 mg, bisoprolol 20 mg, and placebo 1 h before bicycle ergometry (50, 75 and 100 W each for 3 min) in a randomized, cross-over study. Cardiac output was determined by pulmonary uptake of soluble and inert gas tracers (InnoCor, Innovision). Central systolic blood pressure (SBP) was determined from the late systolic shoulder of the digital artery pressure waveform (Finometer, Finopres).

RESULTS

At rest, both beta-ARB reduced brachial but not central SBP (compared with placebo). During exercise, beta-ARB reduced brachial SBP (reductions of 19.9 +/- 4.3 mmHg and 23.2 +/- 2.7 mmHg for propranolol and bisoprolol, respectively, at 100 W, each P < 0.0001) but not central SBP. The difference between peripheral and central SBP was reduced, relative to that during placebo, by 21.5 mmHg (95% confidence interval 8.8, 34.1) and 26.4 mmHg (18.1, 34.8) for propranolol and bisoprolol, respectively, at 100 W (each P < 0.01). There was no significant effect of beta-ARB on diastolic blood pressure or peripheral vascular resistance.

CONCLUSIONS

Despite reducing brachial blood pressure, acute beta-adrenoreceptor blockade in man at rest and during exercise does not reduce central blood pressure.