Higher Root Mean Square Of Successive Differences Research Articles

Potassium excretion and blood pressure are associated with heart rate variability in healthy black adults: The African-PREDICT study

Background and aimsHeart rate variability (HRV) is a main determinant of autonomic function and related to the development of hypertension and cardiovascular (CV) disease. Hypertension develops in black populations at an earlier age, which could be due to differences in the autonomic nervous system activity and sodium/potassium handling in black and white populations. We investigated whether HRV is associated with 24 h urinary sodium and potassium excretion and blood pressure (BP) in a young bi-ethnic cohort. Methods and resultsWe examined 423 black and 483 white healthy adults (aged 24.5 ± 3.1 years) for 24 h HRV, including standard deviation of normal RR intervals (SDNN) reflecting autonomic variations over time, and root mean square of successive differences (RMSSD) reflecting parasympathetic activity. We measured 24 h urinary sodium and potassium concentration and BP. The black group had lower SDNN and potassium excretion as well as higher RMSSD, sodium and Na/k ratio compared to the white group (all p < 0.05). Only in black individuals, urinary potassium excretion was independently and negatively associated with SDNN (β[95% CI];-0.26[-0.50;-0.02]ms) and RMSSD (−0.14[-0.27;-0.01]ms, p < 0.05). One unit increase in sodium/potassium (Na/K) ratio was associated with higher SDNN (β[95% CI]; 3.04[0.89; 5.19]ms) and RMSSD (1.60[0.41; 2.78]ms) in the black cohort only (both p < 0.001). In both groups elevated 24 h diastolic BP was associated with lower RMSSD (p < 0.05). ConclusionLower potassium excretion and higher Na/K ratio related independently to higher HRV in young and healthy black adults. A better ethnic-specific understanding of sodium and potassium handling is required as part of preventive cardiology, especially in black individuals. Clinical trial registrationClinicalTrials.gov Identifier: NCT03292094; URL: https://clinicaltrials.gov/ct2/show/NCT03292094.

Physiological stress response patterns during a blood donation.

Donating blood is associated with increased psychological stress. This study investigates whether a blood donation induces physiological stress and if response patterns differ by gender, donation experience and non-acute stress. In 372 donors, physiological stress [blood pressure, pulse rate, pulse rate variability (PRV)] was measured at seven moments during routine donation. PRV was assessed using time domain [root mean square of successive differences (RMSSD)] and frequency domain [high frequency (HF) and low frequency (LF) power] parameters. Non-acute stress was assessed by questionnaire. Shape and significance of time course patterns were assessed by fitting multilevel models for each stress measure and comparing men and women, first-time and experienced donors, and donors with high and low levels of non-acute stress. Significant response patterns were found for all stress measures, where levels of systolic blood pressure (F(1,1315) = 24·2, P < 0·001), RMSSD (F(1,1315) = 24·2, P < 0·001), LF (F(1,1627) = 14·1, P < 0·001) and HF (F(1,1624) = 34·0, P < 0·001) increased towards needle insertion and then decreased to values lower than when arriving at the donation centre. Diastolic blood pressure (F(1,1326) = 50·9, P < 0·001) increased and pulse rate (F(1,1393) = 507·4, P < 0·001) showed a U-shaped curve. Significant group effects were found, that is, higher systolic blood pressure/pulse rate in women; higher pulse rate in first-time donors; higher RMSSD at arrival and from screening until leaving in first-time donors; and higher LF and HF in first-time donors. This study shows an increase in physiological stress related to needle insertion, followed by a decrease when leaving the donation centre. Some group effects were also found.

Do lambs perceive regular human stroking as pleasant? Behavior and heart rate variability analyses.

Stroking by humans is beneficial to the human-animal relationship and improves welfare in many species that express intraspecific allogrooming, but very few studies have looked at species like sheep that do not express such contact except around parturition. This study investigated the way lambs perceive regular human tactile contact using behavioral and physiological responses. Twenty-four lambs were reared and bucket-fed in groups of four. All were stroked daily by their familiar caregiver. At 8 weeks of age, the lambs were individually tested in their home pen but in a 1×1m open-barred pen after a 15h period of habituation to physical separation from peers while remaining in visual and auditory contact. Half of the lambs received stroking by their caregiver for 8min and half were exposed to their caregiver’s immobile presence. Heart rate and heart rate variability were recorded and analyzed by 2-min slots over the same interval based on three measures: mean heart rate value (HR), root mean square of successive differences (RMSSD) and standard deviation of all intervals measured between consecutive sinus beats (SDNN). Behavioral responses (ear postures of the lamb and time spent in contact with the familiar caregiver, on the knees of the familiar caregiver, and moving) were recorded throughout the test. Lamb HR decreased continuously while in the presence of their caregiver. Lambs being stroked showed slower HR and higher RMSSD which reflected positive emotional states compared to lambs left unstroked. All behavioral variables were highly correlated with the main component axis of the PCA analyses: the more the animals stayed in contact with their caregiver, the less they moved and the more their ears were hanging. This first component clearly differentiates lambs being stroked or not. Behavioral and physiological observations support the hypothesis that gentle physical contact with the caregiver is perceived positively by lambs.

Vacuum extraction and autonomic balance in human infants

The impact of delivery mode on the cardiac autonomic balance was studied in a sample of 101 full term appropriate for gestational age (AGA) human infants. Cardiac autonomic balance was measured by assessing basic heart rate, and two indicators of vagal tone, the Root Mean Square of Successive Differences (RMSSD) and Standard Deviation of NN-intervals (SDNN) as two different measures of short-term heart rate variability at 2, 6, and 16 weeks postnatal age. Sixty-seven infants were delivered spontaneously, 29 by cesarean section and five by vacuum extraction. Children delivered by vacuum extraction had a significantly lower basic heart rate (P=0.01), higher RMSSD (P=0.0003) and higher SDNN (P=0.0001) at two, but not at six and sixteen weeks, indicating a temporary elevation of cardiac vagal tone in these infants. These data indicate a potential transitory impact of vacuum extraction on autonomic balance persisting until at least two weeks postnatal age.

Heart Rate Variability in Adolescents: Relations to Physical Activity, Fitness, and Adiposity

We determined the degree to which variation in cardiac autonomic modulation was explained by race, sex, moderate-vigorous physical activity (MVPA), cardiovascular fitness (CVF), percent body fat (%BF), waist girth, subcutaneous abdominal adipose tissue (SAAT), and visceral adipose tissue (VAT). Subjects were 304 adolescents; SAAT and VAT values were available for 168 youths. Cardiac parasympathetic modulation (PM) was the root mean square of successive differences (RMSSD). Sympathetic-parasympathetic balance was the ratio of low- to high-frequency power (LFnu:HFnu). MVPA was measured with accelerometry, CVF with a treadmill, %BF with dual-energy x-ray absorptiometry (DXA), and SAAT and VAT with magnetic resonance imaging (MRI). Root mean square of successive differences was higher, and LFnu:HFnu was lower, in blacks than in whites. The final regression model revealed positive relations with CVF and MVPA, and a %BF by race by sex interaction, such that higher %BF was associated with lower RMSSD in black females and higher RMSSD in white females. Higher RMSSD was associated with lower VAT; for SAAT, the relationship was negative for blacks and positive for whites. For LFnu:Hfnu, a negative relationship was seen with MVPA and higher waist girth was associated with a higher ratio in blacks, but not in whites. Both higher VAT and SAAT were related to higher LFnu:HFnu. Black youths had a more favorable HRV profile than white youths. After controlling for age, race, and sex, more favorable HRV profiles were associated with more MVPA, better CVF, and less visceral and subcutaneous adiposity. The deleterious impact of higher adiposity was greater in blacks, especially females, than in whites. Enhancement of cardiac autonomic modulation may be a pathway through which physical activity, fitness, and leanness contribute to cardiovascular health early in life.

Ethnic Differences and Heritability of Heart Rate Variability in African- and European American Youth

This study investigated whether heart rate variability (HRV) in young African-Americans differed from that in young European Americans. It further examined the genetic and/or environmental sources of HRV variance and to what extent they depend on ethnicity or gender in young twins. Subjects were available from 1 data set including 166 subjects (mean age 16 +/- 2 years; 63 African-Americans) and another including 219 twins (11 singletons [4 African-Americans] and 104 pairs [42 African-Americans]; mean age 15 +/- 2 years). HRV was measured over 256 RR intervals in a supine position. Two time-domain variables, the SD of normal RR intervals (SDNN) and the root-mean-square of successive differences (RMSSD) of normal RR intervals, and 3 frequency-domain variables, high-frequency (HF) power, low-frequency (LF) power, and the LF power/HF power ratio, were used. African-Americans had higher RMSSDs (p <0.01) and HF power (p = 0.047) and lower LF power/HF power ratios (p <0.01) than European Americans. These differences remained significant after adjusting for covariates. All HRV parameters were heritable; estimated heritability ranged from 32% to 71%. Model fitting showed no ethnic or gender differences for any measure. SDNN, RMSSD, and HF power were strongly correlated (r values >0.8). One factor explaining >90% of the variance for all 3 measures was identified. The heritability of this combined HRV score was 70%. In conclusion, this study suggests that ethnic differences in HRV already exist in youth, with African-Americans having greater HRV than European Americans. High heritability estimates for HRV measures were observed, and no differences in HRV heritability estimates were noted for ethnicity or gender.

The Influence of Fitness and Fatness on Heart Rate Variability in Black and White Teens

1786 Heart rate variability (HRV) is a non-invasive measurement of cardiac autonomic activity. The root mean square of successive differences (RMSSD), a measurement of HRV in the time domain, provides an index of parasympathetic neural activity (PNA). Higher PNA is linked with longevity. The degree to which lifestyle factors, such as cardiovascular fitness (CVF) and body fatness (%BF), in black and white adolescents influences PNA is not known. PURPOSE: This study investigated the relationships between fitness and fatness and cardiac autonomic activity in teens. METHODS: Subjects were 303 13–18 y olds (119 males; 156 blacks, 147 whites). Each subject completed a graded treadmill test for the determination of sub-maximal CVF and a whole-body dual-energy x-ray absorptiometric scan for %BF. Following 5–10 min of supine rest, 256 beats were captured using a Schiller Cardiovit CS 100 and HRV was recorded as RMSSD. RESULTS: Group comparisons revealed that whites had higher RMSSD than blacks (p<0.05). RMSSD was inversely associated with age (r = −0.16, p<0.01) and positively associated with CVF (r<0.05, p<0.01), but was not associated with %BF (r = −0.07, p>0.05). After adjusting for age, race and sex: (1) CVF explained 2.8% of the variance in RMSSD (p<0.01), and (2) there was an interaction between %BF and race (p<0.05), such that higher %BF was associated with lower RMSSD in blacks, while the reverse was true for whites. CONCLUSIONS: High CVF is associated with more favorable PNA whereas the deleterious affects of high fatness on PNA seemed more clearly defined in blacks than in whites. Supported by NIH (HL64157)

The Influence of Fitness and Fatness on Heart Rate Variability in Black and White Teens

1786 Heart rate variability (HRV) is a non-invasive measurement of cardiac autonomic activity. The root mean square of successive differences (RMSSD), a measurement of HRV in the time domain, provides an index of parasympathetic neural activity (PNA). Higher PNA is linked with longevity. The degree to which lifestyle factors, such as cardiovascular fitness (CVF) and body fatness (%BF), in black and white adolescents influences PNA is not known. PURPOSE: This study investigated the relationships between fitness and fatness and cardiac autonomic activity in teens. METHODS: Subjects were 303 13–18 y olds (119 males; 156 blacks, 147 whites). Each subject completed a graded treadmill test for the determination of sub-maximal CVF and a whole-body dual-energy x-ray absorptiometric scan for %BF. Following 5–10 min of supine rest, 256 beats were captured using a Schiller Cardiovit CS 100 and HRV was recorded as RMSSD. RESULTS: Group comparisons revealed that whites had higher RMSSD than blacks (p<0.05). RMSSD was inversely associated with age (r = −0.16, p<0.01) and positively associated with CVF (r<0.05, p<0.01), but was not associated with %BF (r = −0.07, p>0.05). After adjusting for age, race and sex: (1) CVF explained 2.8% of the variance in RMSSD (p<0.01), and (2) there was an interaction between %BF and race (p<0.05), such that higher %BF was associated with lower RMSSD in blacks, while the reverse was true for whites. CONCLUSIONS: High CVF is associated with more favorable PNA whereas the deleterious affects of high fatness on PNA seemed more clearly defined in blacks than in whites. Supported by NIH (HL64157)