The role of heart rate variability in prognosis for different modes of death in chronic heart failure

Classic risk factors for mortality due to chronic heart failure (CHF), such as low left ventricular ejection fraction, NYHA functional stage, and increased heart rate perform well in the prediction of death from pump failure. The prediction of sudden cardiac death (SCD) remains somewhat problematic. Numerous studies have analyzed the potential contribution heart rate variability (HRV) can make to risk assessment in CHF. The aim of this review was to summarize the literature and identify the role HRV might play in identifying mode of death, as well as overall mortality risk. In studies where all-cause mortality or cardiac events were the clinical end point(s), global and slow oscillatory measures of HRV were the strongest risk predictors. In the fewer studies that used SCD as an end point, the strongest risk factors were HRV measures of short-term oscillations and sympathovagal interaction. We concluded from these findings that different HRV measurements predict different modes of death in CHF.Additionally, further studies using short-term analysis of HRV and non-linear analyses are warranted. Furthermore, studies with multiple end points, which clearly delineate pump failure from SCD, may be useful to identify more clearly the role HRV measures can play in the prediction of SCD.     

Levels of agreement for RR intervals and short-term heart rate variability obtained from the Polar S810 and an alternative system

The aim of this study was to assess the agreement between HRV measures derived from a time series of RR intervals recorded by a standard 12-lead ECG (CP) and a commercially available RR interval recorder (S810). Thirty-three participants (19 males) (median age 36, range 20-63) underwent simultaneous, 5-min, supine RR-interval recordings. Each RR interval time series was analysed using the software supplied with the recording equipment. Two comparisons were then made. First, a comparison of RR interval data recording and editing only was made. Second, comparisons were made for measures of HRV derived from edited RR interval data. Agreement between RR intervals and standard HRV measures were assessed using intraclass correlation coefficient and limits of agreement. Agreement of HRV measures derived from RR intervals recorded and edited by individual systems was not acceptable. Agreement analyses for the number of RR intervals recorded and edited by each systems software showed excellent intraclass correlation coefficients (ICC lower 95% CI > 0.75) and acceptably narrow limits of agreement (LoA). These data indicate that the number of RR intervals recorded by S810 can agree well those recorded from a standard 12-lead ECG. This is true even after application of system specific data editing procedures. Commercial RR-interval recorders may offer a simple, inexpensive alternative to full 12-lead ECG in the recording and editing of RR intervals for subsequent HRV analysis in healthy populations.     

Population recovery of peregrine falcons in central Norway in the 4 decades since the DDT-ban

The breeding population of peregrine falcons (Falco peregrinus) in Norway was almost exterminated by the early 1970’s. Long-term monitoring of breeding pairs has been conducted since 1976 up to present. Peregrine falcons were first established at breeding sites in coastal habitats, where they remained at stable low numbers until the early 1990’s. Starting around 2000, numbers began to increase steadily, and current numbers have now reached historical population levels from the pre-DDT era. We documented a range expansion with increasing numbers of peregrines nesting in the fjords and inland valleys. We found that once a territory was colonized, the probability that a territory remained occupied was high (S > 0.958). During early stages of population recovery, the transitional probabilities of becoming or remaining a breeding territory were high (ψ_N–B > 0.40, ψ_B–B > 0.65) but declined over time, especially in coastal habitats. Moreover, the productivity per nest has also decreased over time at sites in coastal habitats in the former stronghold of the population. The levels of environmental pollutants in eggs of the peregrines have dropped sharply over the last few decades, and contaminant levels now seem to be below critical levels. Eggshells were relatively thin throughout the 1970s, 1980s, and 1990s, but have increased to almost normal levels during the last 2 decades. Reductions in levels of organochlorine pollutants, especially DDT, appear to have been the main factor in explaining the population recovery. The territory dynamics are consistent with density-dependence and the low breeding success of the coastal-breeding peregrines is believed to be caused by declining numbers of colonial seabirds and other prey species.

     

Differential responses of adiposity,inflammation and autonomic function to aerobic versus resistance training in older adults

Background

Increased body fat, autonomic dysfunction and low-grade chronic inflammation are interrelated risk factors implicated in the etiology of several chronic conditions normally presented by older adults.

Objective

This study aims to assess the effectiveness of different training protocols on reducing body fat, improving autonomic function, and decreasing low-grade systemic inflammation in community-dwelling elderly adults.

Methods

Fifty participants (11 men, 68 ± 5.5 years) were randomly allocated into resistance or aerobic training or control groups. Evaluations were done at baseline and following the 8-month intervention period on their body composition (assessed by DXA), inflammatory biomarkers (high-sensitivity C-reactive protein [hs-CRP], tumor necrosis-alpha [TNF-α], interferon-gamma [IFN-γ], interleukins-6 and -10 [IL-6, IL-10]), lipoproteic profile, fasting glycemia, blood pressure, heart rate variability (HRV; frequency and time domains) and aerobic fitness (assessed by six-minute walk distance [6MWD]). A paired t-test was used to detect changes (%Δ = [(post‐test score − pretest score) / pre‐test score] × 100) within groups, while between-group differences were analyzed using the one-way ANOVA or General Linear Models.

Results

A significant change (Δ%) both in total (− 5.4 ± 6.3% and − 3.3 ± 2.9%, respectively) and central body fat (8.9 ± 11.3% and − 4.8 ± 4.5%) was observed in resistance and aerobic training groups, respectively; along with a change in resting systolic and diastolic blood pressures (− 9.2 ± 9.8% and − 8.5 ± 9.6%), heart rate (− 4.6 ± 6.5%), hs-CRP (− 18.6 ± 60.6%), and 6MWD (9.5 ± 6.9%) in response to aerobic training.

Conclusions

The present findings provide further evidence for the benefits of aerobic and resistance training on reducing body fat. Aerobic training was demonstrated to reduce hs-CRP and blood pressure in community-dwelling elderly participants with no serious medical conditions.