Potential force dynamics of heart rate variability reflect cardiac autonomic modulation with respect to posture, age, and breathing pattern

Cardio-respiratory coupling and myocardial recovery in heart failure with reduced ejection fraction

INTRODUCTION

The interaction between the cardiovascular and respiratory systems in healthy subjects is determined by the autonomic nervous system and reflected in respiratory sinus arrhythmia. Recently, another pattern of cardio-respiratory coupling (CRC) has been proposed linking synchronization of heart and respiratory system. However, CRC has not been studied precisely in heart failure (HF) with reduced ejection fraction (EF) (HFrEF) according to the myocardial recovery.

METHODS

10-min resting electrocardiography measurements were performed in persistent HFrEF patients (n=40) who had a subsequent left ventricular EF (LVEF) of ≤ 40 %, HF with recovered EF patients (HFrecEF) (n=41) who had a subsequent LVEF of > 40 % and healthy controls (n=40). Respiratory frequency, respiratory rate, CRC index, time-domain, frequency-domain and nonlinear heart rate variability indices were obtained using standardized software-Kubios™. CRC index was defined as respiratory high-frequency peak minus heart rate variability high-frequency peak.

RESULTS

Respiratory rate was positively correlated with high-frequency (HF) peak (Hz) in both persistent HFrEF group (p<0.001) and HFrecEF group (p<0.001), while respiratory rate was negatively correlated with HF power (ms2) in the healthy controls (p<0.05). CRC index was lowest in the persistent HFrEF group followed by HFrecEF and was high in healthy controls (0.008 vs 0.012 vs 0.056 Hz, p=0.03).

CONCLUSION

CRC index was lowest in patients with impaired myocardial recovery, which indicates that cardio-respiratory synchrony is stronger in persistent HFrEF. This may represent a higher HF peak (Hz)/lower HF power (ms2) and abnormal sympathovagal balance in persistent HFrEF group compared to healthy controls. Further work is underway to tests this hypothesis and determine the utility of CRC index in HF phenotypes and its utility as a potential biomarker of response with neuromodulation.

IMMEDIATE EFFECT OF AN ORTHOSTATIC DEVICE IN AMPUTEES WHO PRACTICE PHYSICAL ACTIVITY

ABSTRACT Introduction: Lower limb amputation affects mainly economically active young adults, causing great socio-economic impact due to impaired work capacity, socialization, and quality of life. Thus, the use of orthostatic devices could make reintegration of the individual back into the work environment possible. Objective: To evaluate the immediate effect of using a postural elevation device on physiological parameters and plantar pressure levels in amputees who practice physical activity. Methods: Sociodemographic and perceived sleep quality data were collected from 14 adults of both sexes with lower limb amputations, who practice physical activity. The participants were placed in postural elevation equipment for a period of 90 minutes with monitoring of physiological parameters such as blood pressure, heart rate, and oxygen saturation. Parameters related to the autonomic nervous system and plantar pressure levels were also evaluated. Data were also collected during recovery at 15- and 30-minute intervals after using the device. Data analysis was performed using two-way ANOVA or a mixed-effects model with Sidak's multiple comparisons test. Results: For all cardiovascular parameters (p>0.05) analyzed, the activation level of the autonomic nervous system (p>0.05), and plantar pressure (p>0.05), no evidence of differences was observed during use of the orthostatic device in all evaluated periods. Conclusion: The use of postural elevation equipment for 90 minutes does not generate, as an immediate effect, changes in physiological parameters and postural control in amputees who practice physical activity. Level of evidence II; Therapeutic studies – investigation of treatment results. Clinical relevance statement .

Noninvasive ventilation can modulate heart rate variability during high-intensity exercise in COPD-CHF patients

OBJECTIVE

to assess the acute effects of non-invasive ventilation (NIV) during high-intensity exercise on heart rate variability (HRV) responses in chronic obstructive pulmonary disease (COPD) and Chronic heart failure (CHF) patients.

METHODS

This was randomized, double blinded and controlled study. Fourteen patients with COPD-HF diagnosis were evaluated. The subjects underwent to the following tests: (I) cardiopulmonary exercise testing (CPET) on a cycle ergometer ramp protocol; (II) 7 days after CPET, patients randomly underwent two constant-load exercise (CLE) with NIV or Sham ventilation until tolerance limit, with 80% of the CPET peak load. R-R intervals (RRi) were continuously collected during rest, exercise and in recovery. Time and frequency domain and nonlinear heart rate variability (HRV) indices were obtained.

RESULTS

NIV resulted in a decrease of Mean iRR, square root of the mean squared differences of successive RRi (rMSSD), RR tri index and high-frequency (HF), nu (p < 0.05) and increase of Mean HR, low-frequency (LF), nu and LF/HF (p < 0.05) during exercise when compared to rest. In addition, NIV during exercise induced lower rMSSD and Sample Entropy when compared with Sham (p < 0.05). Negative correlation was found between forced expiratory volume in 1 second (FEV_1, L) vs HF (nu) during exercise with NIV (p = 0.04; r= -0.58). Furthermore, simple linear regression showed that the FEV₁ (L) affected 30% of the HF (nu) response during the exercise with NIV.

CONCLUSION

NIV during exercise produced enhanced heart rate and autonomic responses in COPD-CHF patients. Additionally, COPD severity is negatively associated with a higher vagal response during exercise with NIV.

Impact of chronic obstructive pulmonary disease on linear and nonlinear dynamics of heart rate variability in patients with heart failure

The objective of this study was to investigate the impact of chronic obstructive pulmonary disease (COPD)-heart failure (HF) coexistence on linear and nonlinear dynamics of heart rate variability (HRV). Forty-one patients (14 with COPD-HF and 27 HF) were enrolled and underwent pulmonary function and echocardiography evaluation to confirm the clinical diagnosis. Heart rate (HR) and R-R intervals (iRR) were collected during active postural maneuver (APM) [supine (10 min) to orthostasis (10 min)], respiratory sinus arrhythmia maneuver (RSA-M) (4 min), and analysis of frequency domain, time domain, and nonlinear HRV. We found expected autonomic response during orthostatic changes with reduction of mean iRR, root mean square of successive differences between heart beats (RMSSD), RR tri index, and high-frequency [HF (nu)] and an increased mean HR, low-frequency [LF (nu)], and LF/HF (nu) compared with supine only in HF patients (P<0.05). Patients with COPD-HF coexistence did not respond to postural change. In addition, in the orthostatic position, higher HF nu and lower LF nu and LF/HF (nu) were observed in COPD-HF compared with HF patients. HF patients showed an opposite response during RSA-M, with increased sympathetic modulation (LF nu) and reduced parasympathetic modulation (HF nu) (P<0.05) compared with COPD-HF patients. COPD-HF directly influenced cardiac autonomic modulation during active postural change and controlled breathing, demonstrating an autonomic imbalance during sympathetic and parasympathetic maneuvers compared with isolated HF.

Reliability of short-term measurements of heart rate variability: Findings from a longitudinal study

Research on heart rate variability (HRV) received increasing attention. This study analysed the reliability of the most common HRV parameters for baseline measurements. 103 healthy students (83 women, M = 21.72 ± 3.31 years) participated in five short-term HRV sessions, each including supine, sitting, and standing positions, respectively, spanning a time interval of eleven months. Relative reliability was evaluated by intraclass correlation coefficients, and absolute reliability by standard errors of measurement, smallest real differences, and 95 % limits of random variation. No systematic mean differences between measurements emerged. Intraclass correlation coefficients were quite low (supine: .49-.64, sitting: .40-.57, standing: .35-.56). Absolute reliability indicators revealed pronounced variations between test and retest. Influences of posture and time between measurements on reliability were small and unsystematic. We conclude that such high levels of within-subjects variability in HRV measurements (a) hamper the detection of changes over time, and (b) should be considered carefully in future analyses.

Heart rate variability in patients with major depression disorder during a clinical autonomic test

Major depression disorder (MDD) patients express dysfunction autonomic nervous system (ANS) and reduced heart rate variability (HRV). However, previous researches mainly focused on examining resting state without considering a series of stimulation tests of ANS between MDD patients and healthy people. For this purpose, 40 healthy people and 40 MDD patients participated and finished 10min clinical autonomic test-Ewing test. Parameters of HRV such as time domain, frequency domain, and nonlinear dynamical parameters were calculated. Most of HRV parameters during Ewing test of MDD patients are lower than healthy people, and inversely, the ratio of low frequency to high frequency is higher when standing up. In addition, heart rate of healthy people in deep breathing and Valsalva test states are higher than that in resting state, nonlinear dynamical parameter (RCMSE1) of healthy people in standing up state is higher than that in Valsalva test state. The experimental results suggest that parasympathetic nervous system of MDD patients is influenced by mental state and become dysfunction under long-term depression, it cannot exert normal physiological functions when it is activated. Sympathetic activity increases on MDD patients, and this enhancement is more obvious which expresses higher complexity of HRV time series.

A theoretical and empirical modeling of anxiety integrated with RDoC and temporal dynamics

The newly launched Research Domain Criteria (RDoC) emphasize specific mechanisms over diagnostic categories of psychopathology. In our view, RDoC provides a useful heuristic for mental health disorders, but does not capture the complexity of psychological data when proposed mechanisms are viewed as static entities. However, temporal and complex system dynamics may advance RDoC's utility. By investigating temporal patterns within trajectories and the interaction of complex networks, we propose that dynamic modeling provides comprehensive methods with which to investigate the etiopathology and maintenance of mental health disorders. We examine applications of dynamical systems to periphery physiology, an RDoC construct that has been widely used in psychological science. A review of the literature suggests methodological problems with aggregate and reductive models. We present a dynamical systems modeling of anxiety which suggests avenues for future biomarker research. This model appears congruent with RDoC and recent learning theory.