Contribution of stroke volume to the change in pulse pressure pattern with age

Pulse Pressure and Cardiovascular and Kidney Outcomes by Age in the Chronic Renal Insufficiency Cohort (CRIC)

BACKGROUND

Wide pulse pressure (PP) is associated with cardiovascular events and the progression of chronic kidney disease (CKD) to kidney failure. PP naturally widens with age, but it is unclear whether the risks associated with greater PP are the same across all ages.

METHODS

We used Cox proportional hazards models to investigate the association of PP with (i) atherosclerotic cardiovascular disease (ASCVD) events or death and (ii) a 50% reduction in estimated glomerular filtration rate or kidney failure in the chronic renal insufficiency cohort (CRIC). We evaluated the association of time-updated PP with these outcomes, accounting for time-updated confounders using inverse probability weighting.

RESULTS

Among 5,621 participants with CKD, every 10-mmHg greater PP was associated with a 6% higher risk of an ASCVD event or death (hazard ratio [HR] = 1.06, 95% CI 1.04, 1.08) and 17% higher risk of the composite kidney outcome (HR = 1.17, 95% CI 1.16, 1.18). Greater PP was associated with a higher risk of ASCVD events or death among participants in the lowest age tertile (21-61 years), but a higher risk of the composite kidney outcome in the oldest age tertile (71-79 years). While wide PP in participants that experienced the primary outcomes was predominantly driven by elevated SBP, PP remained significantly associated with the composite kidney outcome across all ages and with ASCVD events or death in the first age tertile when SBP was added to the Cox regression model.

CONCLUSIONS

Our findings suggest that the mechanism by which PP is associated with adverse outcomes may differ by age.

Age and Sex Differences in the Contribution of Mean Arterial Pressure to Pulse Pressure Before Middle Age

INTRODUCTION

A lower ability to buffer pulse pressure (PP) in the face of increasing mean arterial pressure (MAP) may underlie the disproportionate increase in systolic blood pressure (SBP) in women from young adulthood through middle-aged relative to men.

AIM

To evaluate the contribution of MAP to the change in PP and pressure wave contour in men and women from young adulthood to middle age.

METHODS

Central pressure waveform was obtained from radial artery applanation tonometry in 312 hypertensive patients between 16 to 49 years (134 women, mean age 35 ± 9 years), 185 of whom were on antihypertensive treatment.

RESULTS

Higher MAP levels (≥ 100 mmHg) were significantly associated with higher brachial and central SBP (P < 0.001), PP (P < 0.001), incident wave (P = 0.005), AP (P < 0.001), and PWV (P < 0.001) compared to lower MAP levels. The relationship between MAP and brachial PP (P < 0.001), central PP (P < 0.001), incident wave (P < 0.001), and AP (P < 0.01), but not PWV, strengthens with age. The age-related increase in the contribution of MAP to brachial PP (P < 0.001), central PP (P < 0.001), and incident wave (P < 0.001) was more prominent in women than in men beginning in the fourth decade. In multiple regression analyses, MAP remained a significantly stronger predictor of central PP and incident wave in women than in men, independent of age, heart rate, and antihypertensive treatment. In turn, age remained a significantly stronger predictor of central PP and incident wave in women than in men, independent of MAP, heart rate, and antihypertensive treatment.

CONCLUSIONS

Women of reproductive age showed a steeper increase in PP with increasing MAP, despite comparable increases in arterial stiffness in both sexes. The difference was driven by a greater contribution of MAP to the forward component of the pressure wave in women.

Blood pressure screening in Mata Sector, a rural area of Rwanda

In rural sub-Saharan Africa, knowledge of non-communicable diseases such as high blood pressure (BP) is rather limited. This report provides information about a BP screening in Mata Sector, a rural region in Southern Province of Rwanda. Community-based, house-to-house screening was performed between February and July 2020 on more than 7000 inhabitants. The screening was conducted by a local team composed by 20 community health care workers, five community health care supervisors, and one nurse with hypertension surveillance training. BP and heart rate were recorded after 5 min of resting, using a validated automated oscillometric OMRON M6 IT-HEM-7322-E monitor with Intelli Wrap Cuff (HEM-FL31-E) technology. The mean of the second and third value was retained. BP was normal (<140/90 mm Hg) in 6340 (88%) and elevated in 863 (12%) participants with 95% of unawareness. Grade 1 (140-159/90-99 mm Hg) hypertensive BP readings were detected in 697 (81%), grade 2 (160-179/100-109 mm Hg) in 134 (16%), and grade 3 (≥180/≥110 mm Hg) in 32 (3.7%) individuals. The prevalence of hypertensive readings was significantly age-dependent. Additionally, a slightly greater proportion of participants with high BP (14% versus 11%) had a body mass index (BMI) ≥ 25.0 kg/m2. Also resting heart rate was higher in individuals with high BP (82 versus 77 beats/min). Although individuals identified with occasionally elevated BP values need further confirmatory measurements to establish the diagnosis of hypertension, these data suggest that high BP represents a noteworthy and preventable reason of concern within sub-Saharan Africa.

Pulse pressure and its association with body composition among Chinese men and women without diagnosed hypertension: the China Kadoorie Biobank

BACKGROUND

Wide brachial pulse pressure (PP) has been associated with cardiovascular events, while its population distribution and association with body composition were poorly characterized in large populations.

METHODS

We evaluated the age and sex distributions of PP and its associations with body composition using baseline data from the China Kadoorie Biobank. A total of 434 200 participants without diagnosed hypertension were included in the analysis. Wide PP was defined as PP above 65 mmHg. Body composition variables, including BMI, waist circumference, waist-to-hip ratio (WHR), fat mass index (FMI), fat-free mass index (FFMI), and body fat percentage (BF%), were obtained from bioelectrical impedance analysis.

RESULTS

Overall, 14.3% of the participants had wide PP. Older age was consistently associated with wider PP in women but only after the andropause stage in men. The independent associations of BMI with wide PP were stronger than other body composition measures. The adjusted differences (men/women, mmHg) in PP per standard deviation (SD) increase in BMI (1.55/1.47) were higher than other body composition (BF%: 0.32/0.64, waist circumference: 0.33/0.39; WHR: 0.49/0.42). In addition, sex differences were observed. In men, the per SD difference in PP was higher for FFMI than for FMI (0.91 vs. 0.67, P  < 0.05), whereas in women, it was higher for FMI than for FFMI (1.01 vs. 0.72, P  < 0.05).

CONCLUSION

Our nationwide population-based study presented the sex-specific distribution of PP over age and identified differential associations of PP with fat and fat-free mass in men and women.

Modeling essential hypertension with a closed-loop mathematical model for the entire human circulation

Arterial hypertension, defined as an increase in systemic arterial pressure, is a major risk factor for the development of diseases affecting the cardiovascular system. Every year, 9.4 million deaths worldwide are caused by complications arising from hypertension. Despite well-established approaches to diagnosis and treatment, fewer than half of all hypertensive patients have adequately controlled blood pressure. In this scenario, computational models of hypertension can be a practical approach for better quantifying the role played by different components of the cardiovascular system in the determination of this condition. In the present work we adopt a global closed-loop multi-scale mathematical model for the entire human circulation to reproduce a hypertensive scenario. In particular, we modify the model to reproduce alterations in the cardiovascular system that are cause and/or consequence of the hypertensive state. The adaptation does not only affect large systemic arteries and the heart but also the microcirculation, the pulmonary circulation and the venous system. Model outputs for the hypertensive scenario are validated through assessment of computational results against current knowledge on the impact of hypertension on the cardiovascular system.

Role of atrial natriuretic peptide in the dissociation between flow relations with ventricular mass and function in a community with volume-dependent hypertension

Background

Whether differential effects of volume load on left ventricular mass (LVM) and function occur in sustained volume-dependent primary hypertension, and the impact of atrial natriuretic peptide (ANP) on these effects, is unknown.

Methods

From aortic pressure, velocity and diameter measurements and echocardiography, we determined in an African community (n = 772), the impact of systemic flow-induced increases in central pulse pressure (PPc) and circulating ANP (ELISA) on LVM and indexes of function.

Results

Stroke volume (SV), but not aortic flow (Q), was associated with LVM and mean wall thickness (MWT) beyond stroke work and confounders (p < 0.0001). Adjustments for SV markedly decreased the relationships between PPc and LVMI or MWT. However, neither SV, nor Q were independently associated with either myocardial s', e', or E/e' (p > 0.14) and adjustments for neither SV nor Q modified relationships between PPc and s', e' or E/e' (p < 0.005 to <0.0001). SV was nevertheless strongly and independently associated with ANP (p < 0.0001) and ANP was similarly strikingly associated with s' (p < 0.0001) and e' (p < 0.0005), but not E/e', independent of confounders and several determinants of afterload. Importantly, ANP concentrations were inversely rather than positively associated with LV diastolic dysfunction (DD) (p < 0.005) and lower rather than higher ANP concentrations contributed markedly to the ability to detect DD in those with, but not without LV hypertrophy.

Conclusion

In populations with sustained volume-dependent hypertension, flow (SV)-related increases in PP have a major impact on LV structure, but not on function, an effect attributed to parallel striking beneficial actions of ANP on myocardial function.

Short-term effects of transcatheter aortic valve replacement on blood pressure and cardiac function in elderly patients with severe aortic stenosis

BACKGROUND

Transcatheter aortic valve replacement (TAVR) is a standard treatment for elderly and high-risk patients with aortic valve stenosis (AS); however, its short-term effects on blood pressure (BP) and cardiac function are not clear. Therefore, we aimed to determine the short-term effects of TAVR in elderly patients (>75 years), who reflect the clinical situation in Japan.

METHOD AND RESULTS

Twenty-eight consecutive elderly patients with severe AS and hypertension who underwent TAVR under general anesthesia were retrospectively investigated. All patients had hypertension that was well controlled with antihypertensive drugs. Serum brain natriuretic peptide level and peak velocity in the aortic valve were significantly reduced. TAVR induces an increase in BP that requires additional antihypertensive agents. There was no correlation between the change rate of SBP and stroke volume index (SVI), but there was a positive correlation between the rate of change in pulse pressure (PP) and SVI. This tendency was particularly observed in patients with low brachial-ankle pulse wave velocity (baPWV).

CONCLUSION

We observed post-TAVR hypertension and required additional antihypertensive drugs. The increases in SVI and PP after TAVR resulted in post-TAVR hypertension. Moreover, post-TAVR hypertension is less likely to occur in elderly patients with a high baPWV, which indicates advanced arteriosclerosis.

Attenuated Relationships Between Indexes of Volume Overload and Atrial Natriuretic Peptide in Uncontrolled, Sustained Volume-Dependent Primary Hypertension

BACKGROUND

Whether systolic blood pressure (SBP) control in sustained volume-dependent primary hypertension is associated with blunted ANP (atrial natriuretic peptide) relationships with indexes of volume load is unknown.

METHODS

Systemic hemodynamics (central pressure, echocardiographic aortic velocity and diameter measurements in the outflow tract), circulating ANP concentrations (ELISA assays) and glomerular and tubular function (24-hour urine collections [n=519]) were determined in a community of African ancestry (n=772).

RESULTS

As compared with those with a controlled SBP, those with an uncontrolled SBP (n=198) showed lower ANP concentrations (P<0.005) despite higher stroke volume and cardiac output (P<0.0001) and renal differences consistent with enhanced fluid retention. In those with a controlled SBP, fractional Na⁺ excretion (FeNa⁺; P<0.0005) and creatinine clearance (glomerular filtration rate; P<0.005) were inversely associated with ANP concentrations independent of confounders. Moreover, in those with a controlled SBP, stroke volume and cardiac output (P<0.0001) were independently and positively associated with ANP concentrations. In addition, in those with a controlled SBP, ANP concentrations were independently and inversely associated with systemic vascular resistance (SVR; P<0.0001) and aortic characteristic impedance (Zc; P<0.005). By contrast, in those with uncontrolled SBP, no relationships between either stroke volume (P>0.25), cardiac output (P>0.29), FeNa⁺ (P>0.77), or glomerular filtration rate (P>0.47) and ANP concentrations were noted. Furthermore, in those with an uncontrolled SBP, no relationships between ANP concentrations and SVR or Zc were observed (P>0.34).

CONCLUSIONS

In a population where primary hypertension is strongly volume-dependent, those with an uncontrolled SBP have an attenuated relationship between ANP and both renal and hemodynamic indexes of volume overload and the vascular effects of ANP.

Predictive power of 24-h ambulatory pulse pressure and its components for mortality and cardiovascular outcomes in 11 848 participants recruited from 13 populations

BACKGROUND

The role of pulse pressure (PP) 'widening' at older and younger age as a cardiovascular risk factor is still controversial. Mean PP, as determined from repeated blood pressure (BP) readings, can be expressed as a sum of two components: 'elastic PP' (elPP) and 'stiffening PP' (stPP) associated, respectively, with stiffness at the diastole and its relative change during the systole. We investigated the association of 24-h ambulatory PP, elPP, and stPP ('PP variables') with mortality and composite cardiovascular events in different age classes.

METHOD

Longitudinal population-based cohort study of adults with baseline observations that included 24-h ambulatory BP. Age classes were age 40 or less, 40-50, 50-60, 60-70, and over 70 years. Co-primary endpoints were total mortality and composite cardiovascular events. The relative risk expressed by hazard ratio per 1SD increase for each of the PP variables was calculated from multivariable-adjusted Cox regression models.

RESULTS

The 11 848 participants from 13 cohorts (age 53 ± 16 years, 50% men) were followed for up for 13.7 ± 6.7 years. A total of 2946 participants died (18.1 per 1000 person-years) and 2093 experienced a fatal or nonfatal cardiovascular event (12.9 per 1000 person-years). Mean PP, elPP, and stPP were, respectively, 49.7, 43.5, and 6.2 mmHg, and elPP and stPP were uncorrelated ( r  = -0.07). At age 50-60 years, all PP variables displayed association with risk for almost all outcomes. From age over 60 years to age over 70 years, hazard ratios of of PP and elPP were similar and decreased gradually but differently for pulse rate lower than or higher than 70 bpm, whereas stPP lacked predictive power in most cases. For age 40 years or less, elPP showed protective power for coronary events, whereas stPP and PP predicted stroke events. Adjusted and unadjusted hazard ratio variations were similar over the entire age range.

CONCLUSION

This study provides a new basis for associating PP components with outcome and arterial properties in different age groups and at different pulse rates for both old and young age. The similarity between adjusted and unadjusted hazard ratios supports the clinical usefulness of PP components but further studies are needed to assess the prognostic significance of the PP components, especially at the young age.

Importance of central BP assessment in ISH of the young. Which devices are best suited for practical use?

Isolated systolic hypertension (ISH), defined as brachial systolic blood pressure (bSBP) ≥140 mmHg and diastolic blood pressure (DBP) <90 mmHg, is highly prevalent among young subjects and in the elderly. The prognostic significance of ISH in young individuals remains the object of large debate which might be solved, at least in part, if considering the prognostic role of central BP. For any given value of pBP, the cardiovascular (CV) risk is better defined by central BP (cBP). Young individuals with ISH have long been considered at low CV risk, given the assumption that a "spurious hypertension" phenotype characterized by elevated peripheral (brachial) BP (pBP), normal cBP, and elevated BP amplification was often found in this population. However, this remains to be proven, because many other studies found no differences in BP amplification between ISH and sisto-diastolic hypertension. Despite numerous attempts, methodologies for cBP assessment by non-invasive devices are currently not standardized. As a result, different devices could provide different cBP values despite using the same biological signals. Devices providing accurate estimates of BP amplification as a dimensionless ratio between amplitudes of central and peripheral arterial waveforms might be well suited for clinical purposes in young individuals with ISH. There is urgent need of well-designed prospective studies aiming at longitudinally evaluating the amount of CV risk associated with elevated cBP in young subjects with ISH and their related incremental prognostic value.

Resting Electrocardiogram and Blood Pressure in Young Athletes and Non-Athletes: A 4-year follow-up

A follow-up data on electrocardiogram (ECG) and blood pressure (BP) changes in adolescent athletes are scarce. We compared ECG and BP between adolescent athletes and non-athletes in a 4-year follow-up. A total of 154 youth sports clubs (SC) in Finland and 100 secondary schools for comparison data participated in this observational follow-up study. Those who maintained or adopted SC participation are referred to as "Always athletes" (n=137), those who never participated in SC as "Never athletes" (n=108) and those who dropped out of SC during the follow-up as "Changers" (n=116). The mean age of the participants was 15.5 (0.6) years in all study groups at baseline. Resting ECG including heart rate, PR interval, QRS duration, QRS axis, QRS amplitude, T axis and QT interval and BP were measured from all participants at baseline and after follow-up. "Always athletes" had lower resting heart rate, more negative T-wave axis and higher QRS amplitude than "Never athletes" at baseline and at 4-years (P < 0.05). "Changers" had lower resting heart rate, more negative T-wave axis and higher QRS amplitude, systolic BP and pulse pressure than "Never athletes" at baseline (P < 0.05). None of the observed differences at baseline, were visible at 4-years (P > 0.05) except the difference in T-wave axis (P = 0.028). The significant group x time interaction between "Changers" and "Never athletes" was found for QRS amplitude (P = 0.017). Adolescent athletes have several training-induced cardiovascular adaptations, which return towards the levels of non-athletes after cessation of regular training. This article is protected by copyright. All rights reserved.

Cerebrospinal fluid dynamics coupled to the global circulation in holistic setting: Mathematical models, numerical methods and applications

This paper presents a mathematical model of the global, arterio-venous circulation in the entire human body, coupled to a refined description of the cerebrospinal fluid (CSF) dynamics in the craniospinal cavity. The present model represents a substantially revised version of the original Müller-Toro mathematical model. It includes one-dimensional (1D), non-linear systems of partial differential equations for 323 major blood vessels and 85 zero-dimensional, differential-algebraic systems for the remaining components. Highlights include the myogenic mechanism of cerebral blood regulation; refined vasculature for the inner ear, the brainstem and the cerebellum; and viscoelastic, rather than purely elastic, models for all blood vessels, arterial and venous. The derived 1D parabolic systems of partial differential equations for all major vessels are approximated by hyperbolic systems with stiff source terms following a relaxation approach. A major novelty of this paper is the coupling of the circulation, as described, to a refined description of the CSF dynamics in the craniospinal cavity, following Linninger et al. The numerical solution methodology employed to approximate the hyperbolic non-linear systems of partial differential equations with stiff source terms is based on the Arbitrary DERivative Riemann problem finite volume framework, supplemented with a well-balanced formulation, and a local time stepping procedure. The full model is validated through comparison of computational results against published data and bespoke MRI measurements. Then we present two medical applications: (i) transverse sinus stenoses and their relation to Idiopathic Intracranial Hypertension; and (ii) extra-cranial venous strictures and their impact in the inner ear circulation, and its implications for Ménière's disease.

Independent relationships between renal mechanisms and systemic flow, but not resistance to flow in primary hypertension in Africa

AIMS

Whether renal mechanisms of hypertension primarily translate into increases in systemic vascular resistance (SVR) in all populations is uncertain. We determined whether renal mechanisms associate with either increases in SVR (and impedance to flow) or systemic flow in a community of African ancestry.

METHOD

In a South African community sampled across the full adult age range (n = 546), we assessed stroke volume (SV), peak aortic flow (Q), SVR, characteristic impedance (Zc) and total arterial compliance (TAC) from velocity and diameter measurements in the outflow tract (echocardiography) and central arterial pressures. Renal changes were determined from creatinine clearance (glomerular filtration rate, GFR) and fractional Na+ excretion (FeNa+) (derived from 24-h urine collections).

RESULTS

Independent of confounders (including MAP and pressures generated by the product of Q and Zc), SV (and hence cardiac output) (P < 0.0001) and Q (P < 0.01), but not SVR, Zc or TAC (P = 0.09-0.20) were independently associated with decreases in both GFR (index of nephron number) and FeNa+. Through an interactive effect (P < 0.0001), the impact of GFR on SV or Q was strongly determined by FeNa+ and vice versa. The relationship between the GFR-FeNa+ interaction and either SV or Q was noted in those above or below 50 years of age, although neither GFR, FeNa+ nor the interaction were independently associated with SVR, Zc or TAC at any age.

CONCLUSION

Across the full adult lifespan, in groups of African ancestry, renal mechanisms of hypertension translate into increases in systemic flow rather than into resistance or impedance to flow.

Is Isolated Diastolic Hypertension an Important Phenotype?

PURPOSE OF REVIEW

Isolated diastolic hypertension (IDH) is a frequent hypertension phenotype. We review IDH pathophysiology, risk stratification, and therapeutic decisions.

RECENT FINDINGS

Recent guidelines lowering blood pressure cutoff levels have increased IDH prevalence and likely decreased associated cardiovascular risk. Long-term cardiovascular risk and pharmacological intervention in IDH are controversial. Narrow pulse pressure and other physiological and epidemiological characteristics are shared with a systodiastolic hypertension (SDH) subgroup. We propose that IDH be incorporated into a broader category, predominantly diastolic hypertension (PDH), defined by pulse pressure ≤ 45 mmHg and includes IDH and SDH with a narrow pulse pressure. IDH-PDH is associated with cardiovascular risk in the long term, especially in young patients. Standardization of the IDH definition and population may contribute to future research to understand genetics, pathophysiology, and eventually therapy in this important subgroup of hypertensive patients.

Total Effective Vascular Compliance of a Global Mathematical Model for the Cardiovascular System

In this work, we determined the total effective vascular compliance of a global closed-loop model for the cardiovascular system by performing an infusion test of 500 mL of blood in four minutes. Our mathematical model includes a network of arteries and veins where blood flow is described by means of a one-dimensional nonlinear hyperbolic PDE system and zero-dimensional models for other cardiovascular compartments. Some mathematical modifications were introduced to better capture the physiology of the infusion test: (1) a physiological distribution of vascular compliance and total blood volume was implemented, (2) a nonlinear representation of venous resistances and compliances was introduced, and (3) main regulatory mechanisms triggered by the infusion test where incorporated into the model. By means of presented in silico experiment, we show that effective total vascular compliance is the result of the interaction between the assigned constant physical vascular compliance and the capacity of the cardiovascular system to adapt to new situations via regulatory mechanisms.

The role of the renal resistance index in patients with heart failure with reduced or preserved ejection fraction

BACKGROUND

Renal impairment is a common phenomenon that portends a poor prognosis of heart failure (HF). The renal arterial resistance index (RRI) can be useful for defining renal function and predicting outcomes in patients with HF. This study aimed to investigate the determining factors of the RRI in HF patients with preserved ejection fraction (HFpEF) and with reduced EF (HFrEF).

METHODS

This retrospective study included 330 patients with HF. We investigated the determining factors for the RRI and the association between the RRI and 1-year composite outcome, comprising all-cause mortality and re-hospitalization for HF.

RESULTS

The independent predictors of the RRI were tricuspid regurgitation peak gradient and estimated glomerular filtration rate in HFpEF, and pulse pressure and blood urea nitrogen in HFrEF. During the follow-up, 30 (9.1%) patients presented the composite outcome. Cox proportional hazard analysis revealed the association of the RRI with the composite outcome in both HFrEF (HR 1.08; 95% CI 1.03-1.14) and HFpEF (HR 1.07; 95% CI 1.03-1.12) without an interaction (p for interaction = 0.770).

CONCLUSIONS

The RRI was a consistent prognosticator in patients with HFpEF and those with HFrEF, while factors defining RRI were different between these groups.

The Influence of Resting Heart Rate on Central Pulse Pressure is Age-Dependent

INTRODUCTION

Low resting heart rate (RHR) increases augmentation pressure (AP) and central pulse pressure (central PP) and decreases peripheral pressure wave amplification. Given that the contribution of AP to central PP increases with age we hypothesized that the influence of RHR on AP, central PP and peripheral amplification varies with age.

AIM

To evaluate the interaction between age and RHR on the forward and backward components of central PP.

METHODS

A cohort of 1249 ambulatory hypertensive patients with good quality radial wave recordings was stratified into age groups and quartiles of RHR (< 61, 61-68, 69-76 and > 76 bpm). Central aortic pressure was estimated from radial applanation tonometry.

RESULTS

Forward wave (FW) and AP showed opposite changes until midlife, mutually canceling their effect on central PP, whereas both components of central PP increased in parallel after the fifth decade. The initial fall in FW was expressed in the brachial artery as a corresponding decrease in PP and in peripheral amplification. After midlife there was a further decrease in peripheral amplification at the expense of the rise in central PP. A lower RHR exaggerated the age-related increase in left ventricular ejection time (LVET), AP, central PP, and the decrease in peripheral amplification (P < 0.001, for all the interactions between decades and quartiles of RHR). Multivariable regression analyses (n = 1249) confirmed a significant interaction between age and RHR on central PP (P < 0.001), AP (P < 0.001), LVET (P < 0.001), AIx (P < 0.035), and peripheral amplification (P < 0.001). Multivariable regression analyses stratified by age groups (< 30, 30-59 and ≥ 60 years) showed an increasing strength in the relationship of RHR with AP, independently of sex, mean arterial pressure, pulse wave velocity and beta-blockers use. The average increase in AP for a decrease in 10 bpm was 1.4 mmHg before age < 30 years; 2.5 mmHg between age 30-59 years; and 5.4 mmHg at 60 years and older.

CONCLUSIONS

A lower heart rate exaggerated AP and central PP in an age dependent fashion, being the effect particularly relevant in older patients.

Characteristics and Determinants of Pulse Pressure-Age Relationship in Healthy and Non-treated Hypertensive Subjects of Argentinean Population

BACKGROUND

The relationship between the increases in pulse pressure (PP) and arterial stiffness determined by aging or systemic hypertension has been widely reported. These findings are supported by large-cohort analyzes conducted in well-known populations, such as Framingham Study. However, there is evidence that an age-PP curvilinear relationship may exist in hypertensive subjects. This study aimed to evaluate the age-related change in pulse pressure and arterial stiffness in a population-based study.

METHODS

Carotid-femoral Pulse Wave Velocity (cfPWV) were obtained in 2075 subjects.

RESULTS

Age-related changes of PP showed a curvilinear relationship (R=0.39, p<0.0001) in normotensive subjects, with a nadir at around 50 years of age. On the other hand, the age-cfPWV relationship showed a linear and positive correlation (R=0.72, p<0.0001). PP also showed a curvilinear relationship with age (R=0.36, p<0.0001) in hypertensive subjects, with a nadir around 50 years of age. The age-cfPWV relationship showed a linear and positive correlation (R=0.55, p<0.0001). Similar results were observed in the adult population (age≥16 years). Multivariate analysis showed that age, sex, cfPWV, and mean arterial pressure are determinants of PP values in the entire population; however, this result was not uniform when different subgroups were analyzed.

CONCLUSION

In conclusion, age-related changes in PP showed a curvilinear relationship and no parallelism with the age-cfPWV relationship for both normotensive and hypertensive subjects. The determinants of PP impact it differently depending on age and the pathological condition of the subject.

Ultrasound measurement of fetal arterial pulse pressure using phased-tracking methods: A phantom study and clinical experience with antenatal corticosteroid therapy

AIM

This study aimed to compare the accuracy of fetal pulse pressure estimated with a vascular simulator with that obtained by a manometer (reference) and evaluate the pulse pressure in normal human fetuses and fetuses whose mothers received corticosteroids.

METHODS

Fetal pulse pressure was estimated as the product of blood flow velocity and pulse wave velocity, based on the water hammer equation. Ultrasonic raw radiofrequency signals for blood flow velocity were captured from the fetal descending aortas at the diaphragm level, and pulse wave velocity was simultaneously measured from different directions using the phased-tracking method. First, the precision and accuracy of pulse pressure in the estimated method were verified by a circulatory phantom simulator, which reproduced fetal blood flow using a pulsating pump. Then, the pulse pressure of 98 normal human fetuses after 17 weeks of gestation and the fetal pulse pressure in 21 mothers who received antenatal corticosteroids for fetal maturation were measured.

RESULTS

A significant correlation between the estimated pulse pressure values and the actual values was found in the phantom simulation (r = 0.99, P < 0.01). The estimated pulse pressure was significantly correlated with gestational age in normal fetuses (r = 0.74, P < 0.01). In steroid-treated pregnant women, fetal pulse pressure was observed to increase significantly on the second day of administration (P < 0.01).

CONCLUSION

A noninvasive and accurate estimation model of fetal pulse pressure could be established using phased-tracking method, and this method has the potential to improve the assessment of human fetal hemodynamics.

Distinct Contribution of Systemic Blood Flow to Hypertension in an African Population Across the Adult Lifespan

Although hypertension in groups of African ancestry is volume-dependent, the relative impact of systemic flow (stroke volume, peak aortic flow [Q]) versus vascular mechanisms (systemic vascular resistance, aortic characteristic impedance [Zc], total arterial compliance) components of arterial load has not been evaluated across the adult age range. In participants of African ancestry (n=824, age=16–99 years, 68.3% female), using central arterial pressure and aortic velocity and diameter measurements in the outflow tract, we determined the hemodynamic correlates of age-related increases in blood pressure. Strong independent positive relations between age and stroke volume or peak aortic Q were noted ( P <0.0001), effects associated with ventricular end diastolic volume and aldosterone-to-renin ratios. Age-related increases in mean arterial pressure were associated with stroke volume and not systemic vascular resistance. Although age-Q relations began from early adulthood, initially an inverse association between age and aortic Zc ( P <0.0001) driven by increments in aortic root diameter ( P <0.0001) prevented an enhanced systolic blood pressure and pulse pressure. When Zc began to positively relate to age ( P <0.0001), age-Q relations translated into increases in forward wave pressures and hence systolic blood pressure and pulse pressure. Age relations with pulse pressure were as strongly determined by Q as by Zc or total arterial compliance (0.027±0.001 versus 0.028±0.001 and 0.032±0.003 mm Hg per yearly increase in pulse pressure produced by Q, Zc, and total arterial compliance; P <0.0001). Uncontrolled hypertension (confirmed with 24-hour blood pressure) was determined more by Q, Zc, and total arterial compliance than by increases in systemic vascular resistance ( P <0.0005 for comparison). In conclusion, relationships between age and systemic blood flow contribute markedly to hypertension in groups of African origins.

Non-invasive venous waveform analysis (NIVA) for volume assessment in patients undergoing hemodialysis: an observational study

BACKGROUND

Accurate assessment of volume status to direct dialysis remains a clinical challenge. Despite current attempts at volume-directed dialysis, inadequate dialysis and intradialytic hypotension (IDH) are common occurrences. Peripheral venous waveform analysis has recently been developed as a method to accurately determine intravascular volume status through algorithmic quantification of changes in the waveform that occur at different volume states. A noninvasive method to capture peripheral venous signals is described (Non-Invasive Venous waveform Analysis, NIVA). The objective of this proof-of-concept study was to characterize changes in NIVA signal with dialysis. We hypothesized that there would be a change in signal after dialysis and that the rate of intradialytic change in signal would be predictive of IDH.

METHODS

Fifty subjects undergoing inpatient hemodialysis were enrolled. A 10-mm piezoelectric sensor was secured to the middle volar aspect of the wrist on the extremity opposite to the access site. Signals were obtained fifteen minutes before, throughout, and up to fifteen minutes after hemodialysis. Waveforms were analyzed after a fast Fourier transformation and identification of the frequencies corresponding to the cardiac rate, with a NIVA value generated based on the weighted powers of these frequencies.

RESULTS

Adequate quality (signal to noise ratio > 20) signals pre- and post- dialysis were obtained in 38 patients (76%). NIVA values were significantly lower at the end of dialysis compared to pre-dialysis levels (1.203 vs 0.868, p < 0.05, n = 38). Only 16 patients had adequate signals for analysis throughout dialysis, but in this small cohort the rate of change in NIVA value was predictive of IDH with a sensitivity of 80% and specificity of 100%.

CONCLUSIONS

This observational, proof-of-concept study using a NIVA prototype device suggests that NIVA represents a novel and non-invasive technique that with further development and improvements in signal quality may provide static and continuous measures of volume status to assist with volume directed dialysis and prevent intradialytic hypotension.

Role of Vascular Adaptation in Determining Systolic Blood Pressure in Young Adults

Background Two individuals can have a similar pulse pressure (PP) but different levels of systolic blood pressure (SBP), although the underlying mechanisms have not been described. We hypothesized that, for a given level of PP, differences in SBP relate to peripheral vascular resistance (PVR); and we tested this hypothesis in a large cohort of healthy young adults. Methods and Results Demographic, biochemical, and hemodynamic data from 3103 subjects were available for the current analyses. In both men and women, for a given level of PP, higher SBP was associated with significantly higher body weight, body mass index, heart rate, and PVR (P<0.05 versus those with lower BP for all comparisons). Moreover, stratifying individuals by quartiles of PP and PVR revealed a stepwise increase in SBP from the lowest to highest quartile for each variable, with the highest SBP occurring in those in the highest quartile of both PP and PVR (P<0.001 for overall trend for both sexes). PVR was also increased with increasing tertile of minimum forearm vascular resistance, in both men (P=0.002) and women (P=0.03). Conclusions Increased PVR, mediated in part through altered resistance vessel structure, strongly associates with the elevation of SBP for a given level of PP in young adults. An impaired ability to adapt PVR appropriately to a given level of PP may be an important mechanism underlying elevated SBP in young adults.

Non-Invasive Venous waveform Analysis (NIVA) for monitoring blood loss in human blood donors and validation in a porcine hemorrhage model

STUDY OBJECTIVE

There is an unmet need for a non-invasive approach to diagnose hemorrhage early, before changes in vital signs occur. Non-Invasive Venous waveform Analysis (NIVA) uses a unique physiological signal (the peripheral venous waveform) to assess intravascular volume. We hypothesized changes in the venous waveform would be observed with blood loss in healthy adult blood donors and characterized hemorrhage using invasive monitoring in a porcine model.

DESIGN

Prospective observational study.

SETTING

American Red Cross donation center.

PATIENTS

50 human blood donors and 12 non-donating controls; 7 Yorkshire pigs.

INTERVENTIONS

A venous waveform capturing prototype (NIVA device) was secured to the volar aspect of the wrist in human subjects. A central venous catheter was used to obtain hemodynamic indices and venous waveforms were obtained using the prototype NIVA device over the saphenous vein during 400 mL of graded hemorrhage in a porcine model.

MEASUREMENTS

Venous waveforms were transformed from the time to the frequency domain. The ratiometric power contributions of the cardiac frequencies were used to calculate a NIVA value representative of volume status.

MAIN RESULTS

A significant decrease in NIVA value was observed after 500 mL of whole blood donation (p < .05). A ROC curve for the ability of the NIVA to detect 500 mL of blood loss demonstrated an area under the curve (AUC) of 0.94. In the porcine model, change in NIVA value correlated linearly with blood loss and with changes in hemodynamic indices.

CONCLUSIONS

This study provides proof-of-concept for a potential application of NIVA in detection of blood loss. NIVA represents a novel physiologic signal for detection of early blood loss that may be useful in early triage and perioperative management.

The relationship between pulse pressure, insulin resistance, and beta cell function in non-diabetic Korean adults

AIMS

The present study was conducted to assess the association of pulse pressure (PP) with insulin resistance and beta cell function in Korean non-diabetic populations.

METHODS

This study used the data from the 2015 Korean National Health and Nutrition Examination Survey including 4380 adults, aged 20 or older.

RESULTS

A multivariate analysis revealed that systolic blood pressure (SBP) (β=0.089, 95% confidence interval [CI], 0.004-0.011; p<0.001), diastolic blood pressure (DBP) (β=-0.057, 95% CI -0.014 to -0.003; p=0.002), and PP (β=0.069, 95% CI 0.004-0.011; p<0.001) were significant factors determining the homeostasis model assessment of insulin resistance (HOMA-IR). SBP (β=0.070, 95% CI, 0.113-0.420; p=0.001), DBP (β=-0.068, 95% CI -0.676 to -0.203; p<0.001), and PP (β=0.050, 95% CI 0.115-0.422; p=0.001) were significant factors determining the homeostasis model assessment of beta cell function (HOMA-B). In the analysis of covariance test, after adjusting for related variables (except age), the quartiles of PP were not associated with HOMA-IR (p=0.191) and were inversely associated with HOMA-B (p<0.001). However, when further adjusting for age, the quartiles of PP were positively associated with both HOMA-IR (p<0.001) and HOMA-B (p=0.027).

CONCLUSION

PP was positively associated with insulin resistance and beta cell function in non-diabetic Korean adults.

Isolated systolic hypertension in the young: a position paper endorsed by the European Society of Hypertension

: Whether isolated systolic hypertension in the young (ISHY) implies a worse outcome and needs antihypertensive treatment is still a matter for dispute. ISHY is thought to have different mechanisms than systolic hypertension in the elderly. However, findings from previous studies have provided inconsistent results. From the analysis of the literature, two main lines of research and conceptualization have emerged. Simultaneous assessment of peripheral and central blood pressure led to the identification of a condition called pseudo or spurious hypertension, which was considered an innocent condition. However, an increase in pulse wave velocity has been found by some authors in about 20% of the individuals with ISHY. In addition, obesity and metabolic disturbances have often been documented to be associated with ISHY both in children and young adults. The first aspect to consider whenever evaluating a person with ISHY is the possible presence of white-coat hypertension, which has been frequently found in this condition. In addition, assessment of central blood pressure is useful for identifying ISHY patients whose central blood pressure is normal. ISHY is infrequently mentioned in the guidelines on diagnosis and treatment of hypertension. According to the 2013 European Guidelines on the management of hypertension, people with ISHY should be followed carefully, modifying risk factors by lifestyle changes and avoiding antihypertensive drugs. Only future clinical trials will elucidate if a benefit can be achieved with pharmacological treatment in some subgroups of ISHY patients with associated risk factors and/or high central blood pressure.

Pulse pressure and prognosis in patients with heart failure with reduced ejection fraction

BACKGROUND

A high pulse pressure (PP) is associated with adverse cardiovascular (CV) outcomes; however, this relationship may be reversed in patients with heart failure with reduced ejection fraction (HFREF).

METHODS

Patients from the WARCEF trial with left ventricular ejection fraction ≤35% were included. PP was divided into tertiles: ≤42, 42-54 and >54 mm Hg. Age and ejection fraction adjusted Kaplan-Meier curves were generated to evaluate the relationship between PP and outcomes [mortality, CV mortality, stroke and HF hospitalizations (HFH)]. Cox proportional hazards models were created incorporating PP as a continuous variable. The interaction of PP with New York Heart Association (NYHA) functional class was examined. Linear and restricted cubic splines were used to study nonlinear association between PP and outcomes.

RESULTS

We included 2,299 patients with a mean(±SD) follow-up of 3.5 ± 1.8 years. The lowest tertile of PP (≤42 mm Hg) was associated with significantly higher CV mortality and HFH. Cox proportional hazards models showed a reduction in CV death and HFH with higher PP, with adjusted hazard ratios (HR) of 0.91 (P = 0.02) and 0.93 (P = 0.04) per 10 mm Hg increase in PP. This relationship was more pronounced in subjects with NYHA functional class III-IV. Spline analysis showed that the association between PP and CV mortality and HFH was only seen at PP values lower than 40 mm Hg.

CONCLUSIONS

In patients with advanced HFREF, a low PP (<40 mm Hg) portends a worse prognosis, whereas a high PP (>50 mm Hg) predicts a relatively favourable prognosis.

Ambulatory pulse pressure components: concept, determination and clinical relevance

BACKGROUND

Ambulatory pulse pressure (PP) a well known predictor of mortality, is widely believed to be a marker for arterial stiffness. However stiffness itself is pressure-dependent.

OBJECTIVES

Developing a model-based method for splitting PP into two components expressing the contribution of a pressure-independent stiffness ('elastic', elPP) and the pressure-dependence of stiffness ('stiffening', stPP), and investigating their predictive power for all-cause mortality.

METHODS

Deriving quantitative expressions for elPP and stPP assuming an exponential pressure-volume relationship in arteries, calculated from ambulatory blood pressure (BP) data and estimate standardized hazard ratios with Cox proportional hazards regression in selected patient groups.

RESULTS

Ambulatory BP records of 1999 consecutive hypertensive patients, of whom 103 died from all causes within 5 years, were analyzed. PP, elPP, stPP and stPP/elPP (PP variables) (mean ± SD) were 60 ± 14, 50 ± 10, 10 ± 8 and 0.20 ± 0.14 mmHg, respectively. elPP and stPP were weakly correlated (r = 0.21). Predictive power was found for patients with heart rate less than 70: mean [95% confidence interval] (P value) hazard ratio of PP, stPP and stPP/elPP (adjusted) were 1.48 [1.13-1.95] (P = 0.005), 1.58 [1.20-2.09] (P = 0.001) and 1.78 [1.25-2.52] (P = 0.001), respectively. The elPP (83% of PP) did not show predictive power. None of the PP variables displayed predictive power for the higher-heart-rate subgroup.

CONCLUSION

Ambulatory PP components provide a novel and clinically valuable tool bridging between PP and arterial properties. Replacing PP by its components, taken as independent variables, may improve predictive power. The prognostic significance of the PP for all-cause mortality in elderly hypertensive patients with lower heart rates is dominated by its smaller component that quantifies arterial stiffening with pressure.

Harness Suspension Stress: Physiological and Safety Assessment

: Hanging motionless in a full body harness may result in unwanted events, such as acute hypotension and syncope, which has been termed harness suspension stress (HSS). The etiology of HSS has not been explored, and it is unknown if the type of harness influences the HSS response.

OBJECTIVES

Evaluate hemodynamics, subjective discomfort, and biological markers of muscle damage during 30-minutes suspension; and evaluate differences between harness attachment (frontal or dorsal).

METHODS

Heart rate, blood pressure, biological markers of muscle damage, and subjective discomfort were measured.

RESULTS

Trial time was shorter in the dorsal versus frontal point of attachment. Hemodynamic shift resulted in the dorsal trial which indicated possible perfusion abnormalities.

CONCLUSIONS

Hemodynamic adjustments contributed to early termination observed in the dorsal trial. A frontal point of attachment may be more suitable for extended harness exposure.

Pulsatile operation of a continuous-flow right ventricular assist device (RVAD) to improve vascular pulsatility

Despite the widespread acceptance of rotary blood pump (RBP) in clinical use over the past decades, the diminished flow pulsatility generated by a fixed speed RBP has been regarded as a potential factor that may lead to adverse events such as vasculature stiffening and hemorrhagic strokes. In this study, we investigate the feasibility of generating physiological pulse pressure in the pulmonary circulation by modulating the speed of a right ventricular assist device (RVAD) in a mock circulation loop. A rectangular pulse profile with predetermined pulse width has been implemented as the pump speed pattern with two different phase shifts (0% and 50%) with respect to the ventricular contraction. In addition, the performance of the speed modulation strategy has been assessed under different cardiovascular states, including variation in ventricular contractility and pulmonary arterial compliance. Our results indicated that the proposed pulse profile with optimised parameters (A_pulse = 10000 rpm and ω_min = 3000 rpm) was able to generate pulmonary arterial pulse pressure within the physiological range (9–15 mmHg) while avoiding undesirable pump backflow under both co- and counter-pulsation modes. As compared to co-pulsation, stroke work was reduced by over 44% under counter-pulsation, suggesting that mechanical workload of the right ventricle can be efficiently mitigated through counter-pulsing the pump speed. Furthermore, our results showed that improved ventricular contractility could potentially lead to higher risk of ventricular suction and pump backflow, while stiffening of the pulmonary artery resulted in increased pulse pressure. In conclusion, the proposed speed modulation strategy produces pulsatile hemodynamics, which is more physiologic than continuous blood flow. The findings also provide valuable insight into the interaction between RVAD speed modulation and the pulmonary circulation under various cardiovascular states.

[Current status of noninvasive hemodynamics in hypertension]

Hypertension is a haemodynamic disorder resulting from a persistent mismatch between cardiac output and peripheral resistance. Hypertension undergoes haemodynamic progression during its natural history. Impedance cardiography is a method of evaluating the cardiovascular system that obtains haemodynamic information from beat to beat through the analysis of variations in the impedance of the thorax on the passage of an electric current. Impedance cardiography unmasks the haemodynamic deterioration underlying the increase in blood pressure as age and systolic blood pressure increases. This method may help to improve blood pressure control through individualized treatment with reduction of peripheral resistance, maintenance of cardiac output or its increase, improvement of arterial compliance and preservation of organ-tissue perfusion. It is useful in the management of patients with resistant hypertension, since a greater percentage of patients controlled with changes in the treatment in relation to the haemodynamic measurements are obtained. Impedance cardiography is important and has prognostic utility in relation to a haemodynamic deterioration pattern and increased cardiovascular events.

Age-related change in contribution of stroke volume to central pulse pressure

We investigated age-related change in the contribution of stroke volume (SV) to central PP (cPP). Eighty seven adult subjects who were free of vasoactive agents were included. Subjects were divided into three age groups: young (20-39 years, n = 26), middle (40-49 years, n = 29), and old (≥50 years, n = 32). SV was calculated by Doppler echocardiography. Hemodynamic indices were measured using a brachial cuff-based oscillometric method. The brachial and cPP showed a small decline from the young group to the middle group and a greater rise after 50 years old. SV significantly and positively correlated with brachial (r = 0.53, p < 0.01) and cPP (r = 0.57, p < 0.01) in the young group. In the middle group, the association of SV with brachial pulse pressure was significant (r = 0.38, p = 0.04) and that with cPP was bordering significant (r = 0.34, p = 0.07). No significant association was found between SV and PP in the old group. In conclusion, the contribution of SV to cPP decreases with age. Age-related changes in the determinants of cPP should be considered when investigating the clinical value of cPP.

Sequence of cardiovascular autonomic alterations after fingolimod initiation

BACKGROUND

Homeostasis between heart rate and blood pressure is based on several interacting regulatory reflexes, which become influenced by fingolimod initiation. The aim of this study was to determine the sequence of changes in cardiovascular autonomic regulation after fingolimod initiation.

METHODS

Twenty-seven patients with relapsing-remitting multiple sclerosis underwent continuous electrocardiogram recording during the first 6 hr after the first dose of fingolimod. In addition to the time interval between two consecutive R-peaks (RR interval), blood pressure and heart rate variability (HRV) were measured on hourly basis. Cardiac parasympathetic and sympathetic regulation were assessed by the different components of HRV.

RESULTS

HRV demonstrated an enhancement in cardiac parasympathetic regulation starting 1 hr after the first dose of fingolimod. Blood pressure started to decrease 2 hr and sympathetic cardiac regulation 3 hr after fingolimod initiation. Recovery in RR interval, systolic and diastolic blood pressure, as well as in cardiac autonomic regulation started after 5 hr postdose, whereas pulse pressure (difference between systolic and diastolic blood pressure) continued to increase at the time of hospital discharge.

CONCLUSIONS

RR interval, blood pressure, as well as the parasympathetic and sympathetic components of cardiac autonomic regulation alter sequentially in different temporal pattern after fingolimod initiation. These findings enhance the understanding of the effects of fingolimod initiation on cardiovascular autonomic regulation in real life.

Dynamic Measurement of Hemodynamic Parameters and Cardiac Preload in Adults with Dengue: A Prospective Observational Study

Few previous studies have monitored hemodynamic parameters to determine the physiological process of dengue or examined inferior vena cava (IVC) parameters to assess cardiac preload during the clinical phase of dengue. From January 2013 to July 2015, we prospectively studied 162 hospitalized adults with confirmed dengue viral infection using non-invasive cardiac output monitoring and bedside ultrasonography to determine changes in hemodynamic and IVC parameters and identify the types of circulatory shock that occur in patients with dengue. Of 162 patients with dengue, 17 (10.5%) experienced dengue shock and 145 (89.5%) did not. In patients with shock, the mean arterial pressure was significantly lower on day 6 after fever onset (P = 0.045) and the pulse pressure was significantly lower between days 4 and 7 (P<0.05). The stroke volume index and cardiac index were significantly decreased between days 4 and 15 and between days 5 and 8 after fever onset (P<0.05), respectively. A significant proportion of patients with dengue shock had an IVC diameter <1.5 cm and IVC collapsibility index >50% between days 4 and 5 (P<0.05). Hypovolemic shock was observed in 9 (52.9%) patients and cardiogenic shock in 8 (47.1%), with a median (interquartile range) time to shock onset of 6.0 (5.0–6.5) days after fever onset, which was the median day of defervescence. Intravascular hypovolemia occurred before defervescence, whereas myocardial dysfunction occurred on the day of defervescence until 2 weeks after fever onset. Hypovolemic shock and cardiogenic shock each occurred in approximately half of the patients with dengue shock. Therefore, dynamic measures to estimate changes in hemodynamic parameters and preload should be monitored to ensure adequate fluid therapy among patients with dengue, particularly patients with dengue shock.

Left Ventricular Systolic Dysfunction in Asymptomatic Black Hypertensive Subjects

BACKGROUND

Hypertension has been established as one of the commonest causes of heart failure especially in sub-Saharan Africa. We have previously observed a high prevalence of left ventricular (LV) systolic dysfunction in hypertensive heart failure patients in Nigeria despite a low prevalence of ischemic heart disease. The present study was, therefore, undertaken to assess the prevalence of asymptomatic LV systolic dysfunction in hypertensive black African subjects with no history of heart failure.

METHODS

One thousand nine hundred forty-seven hypertensive subjects without heart failure presenting to the Cardiology Unit, Department of Medicine, University of Abuja Teaching Hospital, Nigeria, from April 2006 to August 2013 had clinical and echocardiographic evaluation.

RESULTS

Nine hundred fifty-three (48.9%) were males and 994 (51.1%) were females. One thousand eight hundred seventeen (93.3%) had normal LV systolic function (LV ejection fraction (LVEF) ≥ 54%), 68 (3.5%) had mild LV systolic dysfunction (LVEF 45-54%), 43 (2.3%) had moderate LV systolic dysfunction (LVEF 30-44%), and 16 (0.9%) had severe LV systolic dysfunction (LVEF < 30%). Male subjects had worse LV systolic function compared to women (mean LVEF 73.2% vs. 75.6%, P value < 0.0001) and diabetic subjects had worse LV systolic function compared to nondiabetic subjects (LVEF 72.3% vs. 75.7%, P = 0.02). In multivariate regression analysis, lower LVEF as a continuous variable was associated with older age, male sex, diabetes mellitus, LV mass indexed for body surface area, diastolic blood pressure, posterior wall thickness in diastole, left atrial diameter, and LV internal diameter in diastole.

CONCLUSIONS

In a cohort of asymptomatic Black hypertensive subjects, 6.7% had LV systolic dysfunction, which was associated with male gender, diabetes mellitus, and larger LV mass.

Abnormal stress-related measures of arterial stiffness in middle-aged and elderly men and women with impaired fasting glucose at risk for a first episode of symptomatic heart failure

Background

Abnormal resting arterial stiffness is present in middle‐aged and elderly persons with abnormalities of fasting glucose (diabetes or impaired fasting glucose) and is associated with exercise intolerance. We sought to determine whether these same persons exhibited stress‐related abnormalities of arterial stiffness.

Methods and Results

We analyzed dobutamine magnetic resonance stress imaging results from 373 consecutively recruited persons aged 55 to 85 years with normal fasting glucose, impaired fasting glucose, or diabetes who were at risk for but without symptomatic heart failure. Personnel blinded to participant identifiers measured arterial stiffness (brachial pulse pressure/left ventricular stroke volume indexed to body surface area, the aortic elastance index [brachial end‐systolic pressure/left ventricular stroke volume indexed to body surface area], and thoracic aortic distensibility) at 80% of the maximum predicted heart rate response for age. Participants averaged 69±8 years of age; 79% were white, 92% were hypertensive, and 66% were women. After accounting for hypertension, sex, coronary artery disease, smoking, medications, hypercholesterolemia, and visceral fat, we observed an effect of glycemic status for stress measures of arterial stiffness in those with diabetes and impaired fasting glucose relative to those with normal fasting glucose (P=0.002, P=0.02, and P=0.003, respectively).

Conclusion

Middle‐ and older‐aged individuals with diabetes or impaired fasting glucose have higher stress measures of arterial stiffness than those with normal fasting glucose. These data emphasize the need for future studies with larger sample sizes to determine whether stress‐related elevations in arterial stiffness are related to exercise intolerance and future episodes of heart failure experienced by those with abnormalities of fasting glucose.

Clinical Trial Registration

URL: http://clinicaltrials.gov/. Unique identifier: NCT00542503.

Autonomic dysfunction affects dynamic cerebral autoregulation during Valsalva maneuver: comparison between healthy and autonomic dysfunction subjects

The role of autonomic nervous system (ANS) in adapting cerebral blood flow (CBF) to arterial blood pressure (ABP) fluctuations [cerebral autoregulation (CA)] is still controversial. We aimed to study the repercussion of autonomic failure (AF) on dynamic CA during the Valsalva maneuver (VM). Eight AF subjects with familial amyloidotic polineuropahty (FAP) were compared with eight healthy controls. ABP and CBF velocity (CBFV) were measured continuously with Finapres and transcranial Doppler, respectively. Cerebrovascular response was evaluated by cerebrovascular resistance index (CVRi), critical closing pressure (CrCP), and resistance-area product (RAP) changes. Dynamic CA was derived from continuous estimates of autoregulatory index (ARI) [ARI(t)]. During phase II of VM, FAP subjects showed a more pronounced decrease in normalized CBFV (78 ± 19 and 111 ± 16%; P = 0.002), ABP (78 ± 19 and 124 ± 12%; P = 0.0003), and RAP (67 ± 17 and 89 ± 17%; P = 0.019) compared with controls. CrCP and CVRi increased similarly in both groups during strain. ARI(t) showed a biphasic variation in controls with initial increase followed by a decrease during phase II but in FAP this response was blunted (5.4 ± 3.0 and 2.0 ± 2.9; P = 0.033). Our data suggest that dynamic cerebral autoregulatory response is a time-varying phenomena during VM and that it is disturbed by autonomic dysfunction. This study also emphasizes the fact that RAP + CrCP model allowed additional insights into understanding of cerebral hemodynamics, showing a higher vasodilatory response expressed by RAP in AF and an equal CrCP response in both groups during the increased intracranial and intrathoracic pressure, while classical CVRi paradoxically suggests a cerebral vasoconstriction.

Excessive pulse pressure response to standing in community population with orthostatic systolic hypertension

The postural change of pulse pressure (PP) in the persons with orthostatic hypertension (OHT) is unclear. This study included 2849 (65.0 ± 9.3 years) community participants. Blood pressures (BPs) in supine and standing positions were measured. The differences between upright and supine BP and PP were recorded as ΔBP and ΔPP. The criteria for OHT was ΔBP ≥10 mm Hg, for orthostatic hypotension (OH) was ≤-10 mm Hg and for orthostatic normotension (ONT) was -9 to 9 mm Hg. Fasting blood lipids and glucose were measured. The supine SBP of the sOHT group were similar to that of sONT group (140.9 ± 20.2 mm Hg vs 138.2 ± 19.7 mm Hg), but significantly lower than that of sOH group (151.9 ± 19.2 mm Hg; P < .05). Their PPs were 65.3 ± 15.9, 62.8 ± 14.7, and 71.1 ± 15.1 mm Hg, respectively, and with the similar group difference like SBP. When the position changed from supine to standing, the sOHT group showed PP rise, while sOH and sONT groups showed PP reduction (3.8 ± 7.1 mm Hg vs -17.0 ± 8.5 mm Hg and -5.8 ± 6.6 mm Hg; both P < .05). Thus, the standing PP in the sOHT group was significantly higher than in the sONT (69.1 ± 18.0 mm Hg vs 57.0 ± 15.8 mm Hg; P < .05) and in the sOH (54.2 ± 15.2 mm Hg; P < .05) groups. The postural PP profile varies with the postural responses of SBP. The sOHT group has obviously increased PP and significantly higher standing PP compared with the sONT group.

Decreased stroke volume−brachial pulse pressure ratio in patients with type 2 diabetes over 50 years: the role of peripheral neuropathy

BACKGROUND AND AIMS

To document the stroke volume to pulse pressure ratio (SV/PP, an index of total arterial compliance) and its correlates in patients with type 2 diabetes (T2DM) aged over 50 years whose peripheral neuropathy and silent myocardial ischemic (SMI) status were known.

METHODS AND RESULTS

A total of 360 patients with T2DM aged ≥ 50 years, without cardiac history or symptom, left ventricular systolic dysfunction, dilatation and hypokinesia, were retrospectively enrolled. The SV/PP was calculated from echocardiographic left ventricular measurements and brachial blood pressure at rest. Peripheral neuropathy was defined as the presence of any two or more of the following: neuropathic symptoms, decreased distal sensation, or decreased or absent ankle reflexes. SMI was defined as an abnormal stress myocardial scintigraphy and/or stress echocardiography. A low SV/PP ratio (<0.53 ml/m²/mmHg, first tertile) was associated with age, creatinine clearance, 24 h urinary albumin excretion rate, peripheral neuropathy, hypertension, serum total cholesterol and triglycerides levels (p < 0.05-0.0001). In multivariate analysis, age (OR 1.1 [1.0-1.2], p < 0.01), triglycerides (OR 1.5 [1.2-2.0], p = 0.01) and peripheral neuropathy (OR 2.2 [1.2-3.9], p = 0.009) were independently associated with a low SV/PP. The patients with peripheral neuropathy had lower SV (p < 0.01) and higher PP (p < 0.05) than those without, and only lower SV after adjustment for age and nephropathy. Similar results were obtained in the patients with and without SMI.

CONCLUSION

Peripheral neuropathy was independently associated with decreased SV/PP, mainly through decreased SV, in patients with T2DM over 50 years.

Blood pressure-renal blood flow relationships in conscious angiotensin II- and phenylephrine-infused rats

Chronic ANG II infusion in rodents is widely used as an experimental model of hypertension, yet very limited data are available describing the resulting blood pressure-renal blood flow (BP-RBF) relationships in conscious rats. Accordingly, male Sprague-Dawley rats (n = 19) were instrumented for chronic measurements of BP (radiotelemetry) and RBF (Transonic Systems, Ithaca, NY). One week later, two or three separate 2-h recordings of BP and RBF were obtained in conscious rats at 24-h intervals, in addition to separate 24-h BP recordings. Rats were then administered either ANG II (n = 11, 125 ng·kg(-1)·min(-1)) or phenylephrine (PE; n = 8, 50 mg·kg(-1)·day(-1)) as a control, ANG II-independent, pressor agent. Three days later the BP-RBF and 24-h BP recordings were repeated over several days. Despite similar increases in BP, PE led to significantly greater BP lability at the heart beat and very low frequency bandwidths. Conversely, ANG II, but not PE, caused significant renal vasoconstriction (a 62% increase in renal vascular resistance and a 21% decrease in RBF) and increased variability in BP-RBF relationships. Transfer function analysis of BP (input) and RBF (output) were consistent with a significant potentiation of the renal myogenic mechanism during ANG II administration, likely contributing, in part, to the exaggerated reductions in RBF during periods of BP elevations. We conclude that relatively equipressor doses of ANG II and PE lead to greatly different ambient BP profiles and effects on the renal vasculature when assessed in conscious rats. These data may have important implications regarding the pathogenesis of hypertension-induced injury in these models of hypertension.

Positional circulatory control in the sleeping infant and toddler: role of the inner ear and arterial pulse pressure

Heart rate (HR) and arterial blood pressure (BP) are rapidly and reflexively adjusted as body position and the force/direction of gravity alters. Anomalies in these mechanisms may predispose to circulatory failure during sleep. We analysed the development of two key reflexes involved by undertaking a longitudinal (birth–1 year) comparison of instantaneous HR and BP changes evoked by abrupt upright, sideways or horizontal repositioning. Each manoeuvre triggered an identical rise in HR (tachycardia) followed by a slower rise in diastolic blood pressure (DBP)/systolic blood pressure (SBP) and variable pulse pressure (PP) change. We show that tachycardia is triggered by acceleration (vestibular) sensors located in the inner ear and slight changes in the pulsatile component of BP then signal to the arterial baroreceptors to reinforce or oppose these actions as needed. We also identified a PP anomaly in sleeping 1-year-olds of smokers that prematurely slows HR and is associated with mild positional hypotension. We conclude that positional circulatory compensation is initiated pre-emptively in a feed-forward manner and that feedback changes in vago-sympathetic drive to the heart (and perhaps blood vessels) by PP exert a slower but powerful modulating effect. An anomaly in either or both mechanisms may weaken positional compensation in some sleeping infants.