Twenty-four-hour profile of central blood pressure and central-to-peripheral systolic pressure amplification

Influence of acute dietary nitrate supplementation timing on nitrate metabolism, central and peripheral blood pressure and exercise tolerance in young men

PURPOSE

Dietary nitrate (NO3-) supplementation can lower systolic blood pressure (SBP) and improve exercise performance. Salivary flow rate (SFR) and pH are key determinants of oral NO3- reduction and purported to peak in the afternoon. We tested the hypotheses that NO3--rich beetroot juice (BR) would increase plasma [nitrite] ([NO2-]), lower SBP and improve exercise performance to a greater extent in the afternoon (AFT) compared to the morning (MORN) and evening (EVE).

METHOD

Twelve males completed six experimental visits in a repeated-measures, crossover design. NO3--depleted beetroot juice (PL) or BR (~ 13 mmol NO3-) were ingested in the MORN, AFT and EVE. SFR and pH, salivary and plasma [NO3-] and [NO2-], brachial SBP and central SBP were measured pre and post supplementation. A severe-intensity exercise tolerance test was completed to determine cycling time to exhaustion (TTE).

RESULTS

There were no between-condition differences in mean SFR or salivary pH. The elevation in plasma [NO2-] after BR ingestion was not different between BR-MORN, BR-AFT and BR-EVE. Brachial SBP was unchanged following BR supplementation in all conditions. Central SBP was reduced in BR-MORN (- 3 ± 4 mmHg), BR-AFT (- 4 ± 3 mmHg), and BR-EVE (- 2 ± 3 mmHg), with no differences between timepoints. TTE was not different between BR and PL at any timepoint.

CONCLUSION

Acute BR supplementation was ineffective at improving TTE and brachial SBP and similarly effective at increasing plasma [NO2-] and lowering central SBP across the day, which may have implications for informing NO3- supplementation strategies.

The influence of body composition and fat distribution on circadian blood pressure rhythm and nocturnal mean arterial pressure dipping in patients with obesity

Loss of physiological nocturnal blood pressure (BP) decline is an independent predictor of cardiovascular risk and mortality. The aim of the study was to investigate the influence of body composition and fat distribution on 24-hour BP pattern and nocturnal dipping of mean arterial pressure (MAP) in patients with obesity. The study comprised 436 patients, 18 to 65 years old (306 women), with BMI ≥30 kg/m2. Body composition was assessed with dual-energy X-ray absorptiometry (DXA) and blood pressure was assessed by 24-hour BP monitoring. The prevalence of hypertension was 64.5% in patients with BMI <40 kg/m2 and increased to 78.7% in individuals with BMI ≥50 kg/m2 (p = 0.034). The whole-body DXA scans showed that the hypertensive patients were characterized by a greater lean body mass (LBM) and a higher abdominal-fat-to-total-fat-mass ratio (AbdF/FM), while the normotensive participants had greater fat mass, higher body fat percentage and more peripheral fat. Loss of physiological nocturnal MAP decline was diagnosed in 50.2% of the patients. The percentage of non-dippers increased significantly: from 38.2% in patients with BMI <40 kg/m2 to 50.3% in those with BMI 40.0-44.9 kg/m2, 59.0% in patients with BMI 45.0-49.9 kg/m2, 71.4% in those with BMI 50.0-54.9 kg/m2 and 83.3% in patients with BMI ≥55 kg/m2 (p = 0.032, p = 0.003, p<0.001, and p = 0.002 vs. BMI <40 kg/m2, respectively). The multivariable regression analysis showed that patients at the highest quartiles of body weight, BMI, LBM and AbdF/FM had significantly reduced nocturnal MAP dipping compared with patients at the lowest quartiles, respectively.

Superiority of 24-Hour Aortic Over 24-Hour Brachial Pressure to Associate With Carotid Arterial Damage on the Basis of Pressure Amplification Variability: the SAFAR Study

BACKGROUND

Evidence suggests marginal superiority of static aortic systolic blood pressure (aSBP) compared with brachial SBP regarding the association with organ damage and prognosis of cardiovascular disease. The noninvasive 24-hour aSBP assessment is feasible and associates better with presence of left ventricular hypertrophy compared with 24-hour brachial systolic blood pressure. We aimed at comparing the association of 24-hour aSBP and 24-hour brachial systolic blood pressure with indices of arterial damage and examining the role of 24-hour SBP amplification variability (within-subjects' SD) in this association.

METHODS

Consecutive subjects referred for cardiovascular disease risk assessment underwent 24-hour aortic and brachial ambulatory BP monitoring using a validated oscillometric device (Mobil-O-Graph). Arterial damage was assessed by carotid intima-media thickness and detection of carotid and femoral atheromatosis (plaque presence).

RESULTS

Cross-sectionally 501 individuals (aged 54±13 years, 57% men, 80% hypertensives) were examined. Multivariable analysis revealed superiority of 24-hour aSBP regarding the association with intimal-medial thickness, carotid hypertrophy and carotid-but not femoral-atheromatosis. In receiver operator characteristics analysis, 24-hour aBP displayed a higher discriminatory ability-compared to 24-hour brachial systolic blood pressure-for the detection of both carotid hypertrophy (area under the curve, 0.662 versus 0.624, P<0.05) and carotid atheromatosis (area under the curve, 0.573 versus 0.547, P<0.05). This effect was more prominent in individuals with above-median 24-hour SD of SBP amplification.

CONCLUSIONS

Our results suggest that 24-hour aSBP assessment may be of significant value in clinical practice to detect site-specific arterial damage on the basis of pressure amplification variability and should be prospectively examined in clinical trials.

Twenty-Four-Hour Central (Aortic) Systolic Blood Pressure: Reference Values and Dipping Patterns in Untreated Individuals

Supplemental Digital Content is available in the text.

Central (aortic) systolic blood pressure (cSBP) is the pressure seen by the heart, the brain, and the kidneys. If properly measured, cSBP is closer associated with hypertension-mediated organ damage and prognosis, as compared with brachial SBP (bSBP). We investigated 24-hour profiles of bSBP and cSBP, measured simultaneously using Mobilograph devices, in 2423 untreated adults (1275 women; age, 18–94 years), free from overt cardiovascular disease, aiming to develop reference values and to analyze daytime-nighttime variability. Central SBP was assessed, using brachial waveforms, calibrated with mean arterial pressure (MAP)/diastolic BP (cSBP_MAP/DBPcal), or bSBP/diastolic blood pressure (cSBP_SBP/DBPcal), and a validated transfer function, resulting in 144 509 valid brachial and 130 804 valid central measurements. Averaged 24-hour, daytime, and nighttime brachial BP across all individuals was 124/79, 126/81, and 116/72 mm Hg, respectively. Averaged 24-hour, daytime, and nighttime values for cSBP_MAP/DBPcal were 128, 128, and 125 mm Hg and 115, 117, and 107 mm Hg for cSBP_SBP/DBPcal, respectively. We pragmatically propose as upper normal limit for 24-hour cSBP_MAP/DBPcal 135 mm Hg and for 24-hour cSBP_SBP/DBPcal 120 mm Hg. bSBP dipping (nighttime-daytime/daytime SBP) was −10.6 % in young participants and decreased with increasing age. Central SBP_SBP/DBPcal dipping was less pronounced (−8.7% in young participants). In contrast, cSBP_MAP/DBPcal dipping was completely absent in the youngest age group and less pronounced in all other participants. These data may serve for comparison in various diseases and have potential implications for refining hypertension diagnosis and management. The different dipping behavior of bSBP versus cSBP requires further investigation.

Insight into the 24-hour ambulatory central blood pressure in adolescents and young adults

This study attempted to investigate the behavior of 24-hour central ambulatory blood pressure (ABP) in adolescents and young adults. Adolescents and young adults (age 10-25 years) referred for elevated blood pressure (BP) and healthy volunteers had simultaneous 24-hour peripheral (brachial) and central (aortic) ABP monitoring using the same automated upper-arm cuff device (Mobil-O-Graph 24h PWA). Central BP was calculated by the device using two different calibration methods (C1SBP using peripheral systolic (pSBP)/diastolic BP and C2SBP using mean arterial/diastolic BP). A total of 136 participants (age 17.9 ± 4.7 years, 54% adolescents, 77% males, 25% volunteers, 34% with elevated peripheral ABP) were analyzed. Twenty-four-hour pSBP was higher than C1SBP, with this difference being more pronounced during daytime than nighttime (16.3 ± 4.5 and 10.5 ± 3.2 mm Hg, respectively, P < .001). Younger age, higher body height, and male gender were associated with greater systolic ABP amplification (pSBP-C1SBP difference). C1SBP followed the variation pattern of pSBP, yet with smaller nighttime dip (8.4 ± 6.0% vs 11.9 ± 4.6%, P < .001), whereas C2SBP increased (2.4 ± 7.2%) during nighttime sleep (P < .001 for comparison with pSBP change). Older age remained independent determinant of larger nighttime BP fall for pSBP and C1SBP, whereas male gender predicted a larger nighttime C2SBP rise. These data suggest that the calibration method of the BP monitor considerably influences the diurnal variation in central BP, showing a lesser nocturnal dip than pSBP or even nocturnal BP rise, which are determined by the individual's age and gender.

Diurnal changes in central blood pressure and pulse pressure amplification in patients with obstructive sleep apnoea

STUDY OBJECTIVES

Recent evidence suggests that compared to peripheral blood pressure (BP), central BP may be more strongly associated with target organ damage and cardiovascular morbidity and mortality. Technological advances now allow the ambulatory measurement of peripheral and central BP over 24 ​h. For the first time, we set out to characterise the diurnal profile of central BP and pulse pressure amplification (PPA) in patients with obstructive sleep apnoea (OSA).

METHODS

In this observational study, patients with moderate to severe OSA underwent 24 ​h central and peripheral BP testing before and after at least 4 weeks of CPAP therapy. Concurrent actigraphy was performed to confirm sleep and wake times.

RESULTS

36 patients were screened, 31 had successful testing (mean (SD) age 45 ​± ​10 years, AHI 58 ​± ​27 events/hr, Office BP 136/89 ​± ​10.7/9.5 ​mmHg, 32% on anti-hypertensives, 77% dippers), 21 completed testing post CPAP. Central systolic and diastolic BP followed the same nocturnal dipping profile as peripheral BP, however the peripheral pulse pressure (PP) narrowed in sleep (-3.2 ​mmHg, p ​< ​0.001), whereas the central PP remained unchanged (0.124 ​mmHg, NS), causing a significant reduction in PPA overnight (-10.7%, p ​< ​0.001). The magnitude of dip in central systolic pressure was less than peripheral systolic pressure (by 2.3 ​mmHg, p ​< ​0.001). After treatment with CPAP, the PPA reduction overnight was attenuated (by -3.3%, p ​= ​0.004).

CONCLUSIONS

In moderate to severe OSA, central BP and PPA reduce overnight during sleep. Further randomised controlled studies are needed to quantify the differential effects of CPAP and anti-hypertensives on central versus peripheral BP.

Ambulatory pulse wave monitoring: current and future. Opinion paper of Russian Experts

The predictive value of vascular biomarkers such as pulse wave velocity (PWV), central arterial pressure (CAP), and augmentation index (AIx), obtained through pulse wave analysis (PWA) in resting conditions, has been documented in a variety of patient groups and populations. There are appropriate recommendations on their clinical use in clinical practice guidelines of various scientific societies. Operator-independent methods are currently available for estimating vascular biomarkers also in ambulatory conditions. The acceptable accuracy and reproducibility of ambulatory PWA makes it be a promising tool for evaluating vascular biomarkers in daily-life conditions. This approach may provide an opportunity to further improve the early cardiovascular screening in subjects at risk. However, there is no sufficient evidence to support the routine clinical use of PWA in ambulatory conditions at the moment. In particular, long-term outcome studies are needed to show the predictive value of ambulatory PWV, CAP and AIx values.

Comparison of laboratory and ambulatory measures of central blood pressure and pulse wave reflection: hitting the target or missing the mark?

Prior studies demonstrating clinical significance of noninvasive estimates of central blood pressure (BP) and pulse wave reflection have relied primarily on discrete resting measures. The aim of this study was to compare central BP and pulse wave reflection measures sampled during a single resting laboratory visit against those obtained under ambulatory conditions. The secondary aim was to investigate the reproducibility of ambulatory central BP and pulse wave reflection measurements. Forty healthy participants (21 males; 24 ± 3 years) completed three measurements of brachial artery pulse wave analysis (Oscar 2 with SphygmoCor Inside) in the laboratory followed by 24 hours of ambulatory monitoring. Seventeen participants repeated the 24-hour ambulatory monitoring visit after at least 1 week. Ambulatory measures were divided into daytime (9 AM-9 PM), nighttime (1 AM-6 AM), and 24-hour periods. Compared with laboratory measurements, central systolic BP, augmentation pressure, and augmentation index (with and without heart rate normalization) were higher (all P < .01) during daytime and 24-hour periods but lower during the nighttime period (all P < .001). The drop in nighttime brachial systolic BP was larger than central systolic pressure (Δ -20 ± 6 vs. -15 ± 6 mm Hg; P < .0001). Repeat ambulatory measurements of central BP and pulse wave reflection displayed good-to-excellent intraclass correlation coefficients (r = 0.58-0.86; all P < .01), although measures of pulse wave reflection had higher coefficients of variation (14%-41%). The results highlight absolute differences in central BP and pulse wave reflection between discrete laboratory and ambulatory conditions. The use of ambulatory measures of central BP and pulse wave reflection warrant further investigation for clinical prognostic value.

Mechanisms of pulse pressure amplification dipping pattern during sleep time: the SAFAR study

The difference in pulse pressure (PP) between peripheral arteries and the aorta, called pulse pressure amplification (PPamp), is a well-described physiological phenomenon independently associated with cardiovascular events. Recent studies suggest that it exhibits circadian variability. Our aim was to detect the factors associated with the circadian variability of PPamp. In 497 consecutive subjects (aged 54 years, 56.7% male, 79.7% hypertensives), we assessed the circadian pattern of peripheral and central arterial hemodynamics by 24-hour evaluation of brachial and aortic blood pressure (BP), augmentation index (AI), and pulse wave velocity (PWV) using a validated oscillometric device (Mobil-O-Graph). All parameters exhibited a circadian variation. Sleep dipping (decrease) pattern was observed for PPamp, brachial and aortic systolic BP, mean BP, and PWV, whereas a rising pattern (higher sleep than wake values) was observed for brachial PP, aortic PP, and AI. The factors independently associated with the less sleep dipping in PPamp were older age, lower height, the use of antihypertensive medication, and sleep decrease in arterial stiffness (PWV), whereas female gender, the presence of hypertension, sleep increase of pressure wave reflections (AI), sleep decrease in heart rate, and mean BP were associated with a greater sleep-dipping in PPamp. These data provide further pathophysiological understanding of the mechanisms leading to PPamp dipping. Several implications regarding the clinical use of the aortic and brachial BP, especially during sleep time, are raised that should be addressed in future research.

Methodology and technology for peripheral and central blood pressure and blood pressure variability measurement: current status and future directions - Position statement of the European Society of Hypertension Working Group on blood pressure monitoring and cardiovascular variability

Office blood pressure measurement has been the basis for hypertension evaluation for almost a century. However, the evaluation of blood pressure out of the office using ambulatory or self-home monitoring is now strongly recommended for the accurate diagnosis in many, if not all, cases with suspected hypertension. Moreover, there is evidence that the variability of blood pressure might offer prognostic information that is independent of the average blood pressure level. Recently, advancement in technology has provided noninvasive evaluation of central (aortic) blood pressure, which might have attributes that are additive to the conventional brachial blood pressure measurement. This position statement, developed by international experts, deals with key research and practical issues in regard to peripheral blood pressure measurement (office, home, and ambulatory), blood pressure variability, and central blood pressure measurement. The objective is to present current achievements, identify gaps in knowledge and issues concerning clinical application, and present relevant research questions and directions to investigators and manufacturers for future research and development (primary goal).

Twenty-Four-Hour Ambulatory Pulse Wave Analysis in Hypertension Management: Current Evidence and Perspectives

The predictive value of vascular biomarkers such as pulse wave velocity (PWV), central arterial pressure (CAP), and augmentation index (AIx), obtained through pulse wave analysis (PWA) in resting conditions, has been documented in a variety of patient groups and populations. This allowed to make appropriate recommendations in clinical practice guidelines of several scientific societies. Due to advances in technologies, largely operator-independent methods are currently available for estimating vascular biomarkers also in ambulatory conditions, over the 24 h. According to the acceptable accuracy and reproducibility of 24-h ambulatory PWA, it appears to be a promising tool for evaluating vascular biomarkers in daily life conditions. This approach may provide an opportunity to further improve the early cardiovascular screening in subjects at risk. However, concerning the clinical use of PWA over the 24 h in ambulatory conditions at the moment, there is no sufficient evidence to support its routine clinical use. In particular, long-term outcome studies are needed to show the predictive value of 24-h PWV, CAP, and AIx values, provided by these devices, over and beyond peripheral blood pressure, and to answer the many technical and clinical questions still open. To this regard, the VASOTENS Registry, an international observational prospective study recently started, will help providing answers on a large sample of hypertensive patients recruited worldwide.