The effect of a home-based coaching program on heart rate variability in subacute stroke patients: a randomized controlled trial.

Rafael Correo, de izquierdas, y Alvaro Noboa, magnate conservador, vencieron con un discurso clientelista en el pais mas inestable de America Latina.

Monitoring collegiate soccer players during a congested match schedule: Heart rate variability versus subjective wellness measures.

Introduction: Frailty is a central geriatric syndrome characterized by a state of increased physiological vulnerability. As the key components of frailty are difficult to capture in their entirety, easily measurable and reliable surrogate parameters are desirable. Since frailty influences heart rate variability (HRV), HRV may be such a surrogate parameter. HRV is typically acquired by an ECG, which, however, may not be tolerated by all patients; in some, it may even trigger delirium. Therefore, we sought to measure HRV in a non-contact and unobtrusive way through photoplethysmography imaging (PPGI). Using our previously presented HRV estimation algorithm for PPGI, we investigated whether PPGI could reveal (1) HRV differences between frail and non-frail individuals and (2) the influences of early geriatric rehabilitation on HRV. Methods: The study involved 10 frail geriatric inpatients undergoing early geriatric rehabilitation and 10 healthy community-dwelling older adults. All participants underwent a comprehensive geriatric assessment. HRV measurements using a PPGI system and a reference ECG were made at the beginning and the end of the rehabilitation. HRV in terms of LF/HF ratio was analysed for both intra-individual changes during the geriatric rehabilitation and differences between frail geriatric patients and healthy community-dwelling individuals. Results: Across all geriatric patients, the median LF/HF ratio obtained with PPGI was found to be reduced by 0.178 (24.8%) during early geriatric rehabilitation. The assessment at the end of the rehabilitation revealed a simultaneous improvement of the functional state. Moreover, frail geriatric patients had a higher LF/HF ratio than their community-dwelling counterparts. Both observations in PPGI-based HRV were confirmed by the reference. The capability of PPGI to track intra-individual HRV changes was also analysed; a Spearman correlation of ρ = 1.0 between PPGI-based HRV and reference was achieved for 58.8% of the participants. Conclusion: Early geriatric rehabilitation improves the functional state, which is associated with an increased HRV. PPGI is capable of detecting HRV changes/trends in that age group. While the tracking of intra-individual HRV changes is also possible, its reliability needs improvement. Nevertheless, the capabilities demonstrated in our study and the non-contact measurement principle of PPGI emphasize its potential for application in geriatric medicine.

Heart rate variability (HRV) has been used to investigate the autonomic modulation of heart rate. Diminished HRV has been observed in diabetic autonomic neuropathy, a condition associated with increased mortality. Uraemia is associated with impaired autonomic function, but reports on the effects of uraemia on HRV are scarce. HRV and its circadian variation were studied in 12 diabetic and 11 non-diabetic renal transplantation and in 12 control patients. HRV in time and frequency domains was determined from 24-hour ECG recordings. In the diabetic group, all time domain and frequency domain measures of HRV were markedly reduced (P < 0.05), when compared with the control group, and the circadian variation of HRV was absent. The mean (SD) amplitudes (ms) in the frequency bands were: high frequency: 3 (1), 6 (3) and 15 (3); low frequency: 9 (7), 16 (10) and 25 (8); very low frequency: 14 (8), 23 (12) and 30 (11) in the diabetic and non-diabetic uraemic and in the control patients, respectively. In non-diabetic uraemic patients, a tendency to reduced HRV was observed, but no statistical differences in HRV measures were found when compared with the control group. The severe impairment of HRV in patients with end-stage diabetic nephropathy is probably due to autonomic neuropathy and partly also to the co-existing heart diseases. It may be a contributing risk factor for ventricular arrhythmias and sudden death in these patients. Uraemia alone causes similar but less severe changes in HRV.

Changes in heart rate variability among cardiac resynchronization therapy patients

Effect of the Stroop test performed in supine position on the heart rate variability in both genders.

Changes in heart rhythm variability were studied in male and female mature and 5-6-week-old rats under conditions of 7-day administration of β1-adrenoreceptor blocker atenolol (2.5 mg/kg) and α1-adrenoreceptor agonist phenylephrine (0.3 mg/kg). Atenolol administration to mature rats was followed by a slight deceleration of cardiac rhythm, a tendency to heart rate variability decrease in the HF range, and moderate increase in centralization of regulation. In 6-week-old rats, increased variability of cardiointervals and significant increase of centralization of the heart rhythm regulation due to an increase in the power of low-frequency waves (specifically VLF) were observed. In both mature and young rats, changes of heart rate frequency and variability in response to atenolol administration were more pronounced in females. Phenylephrine administration was followed by a significant heart rate deceleration, increase in cardiointerval variability and centralization of heart rate regulation in mature rats and by a decrease in heart rate variability in all frequency ranges in 6-week-old rats. In mature rats, changes in heart rate frequency and variability produced by phenylephrine administration were more pronounced in males; in young rats, the most strained heart rhythm developed in females.

Changes in heart rate variability in sevoflurane and nitrous oxide anesthesia: effects of respiration and depth of anesthesia

ObjectiveHeart rate variability (HRV) reflects integrity of the autonomic nervous system. However, no study has investigated the impact of therapeutic hypothermia (TH) on HRV measures in infants with hypoxic-ischemic encephalopathy (HIE). In this study, we evaluate the influence of temperature on measures of HRV for a group of infants with favorable outcomes, as compared to a control group of infants with unfavorable outcomes.Study DesignTerm-born infants with moderate-severe HIE underwent standard TH treatment and prospective EEG and ECG recording. Infants with favorable outcome (no seizures, normal/mild EEG scores at 96h, no MRI brain injury, and normal neurodevelopmental scores at 18–24 months) were matched on gestational age, sex and worst encephalopathy score to a group of infants with unfavorable outcomesTime and frequency domain HRV measures were calculated from 60 min of ECG data obtained at three time points: 24h (hypothermia), 48h (hypothermia), and 96h (normothermia). The effect of time and temperature were evaluated using repeated-measures ANOVA.ResultsSixteen infants were included (8 favorable, 8 unfavorable). For both groups of infants, an increase in the HR, RR and HF power was associated with an increase in temperature, but was not associated with any other HRV measure. In contrast, measures of HRV increased over time, as encephalopathy decreased, for infants with favorable outcomes (reflecting increased cortical-autonomic integration), but not for those with unfavorable outcomes.ConclusionIn general, the effect of hypothermia on measures of HRV is limited to changes in heart rate (bradycardia) and respiratory rate, as opposed to changes in true variability. This supports the hypothesis that persistent changes in HRV are driven by the underlying brain injury and not by the process of TH.

Non-invasive positive pressure ventilation (NIPPV) is known to enhance hypoventilation and is particularly adopted as a treatment for patients diagnosed with obesity hypoventilation syndrome (OHS). The augmented risk of cardiovascular morbidity is known as a side effect of OHS. In this paper, this inference is examined that hypoventilation and the increased risk of morbidity can be diagnosed via the assessment of changes in heart rate variability (HRV). More specifically, the study investigates the effect of NIPPV on both HRV and hypoventilation among OHS patients. The linear relationship between different HRV measures and ventilation parameters is also examined. The reported results are attained via an interventional clinical trial study. HRV measures are evaluated before and after treatment, in a group of patients which are newly diagnosed with OHS and receive bi-level positive airway pressure (BiPAP) treatment for three months. The results are compared and interpreted via statistical analysis. Throughout the study, the relationship between hypoventilation and HRV is confirmed, as well as the effect of BiPAP on some HRV measures in both time and frequency domains. Particularly significant connections are observed between hypoventilation and low-frequency components of HRV. The enhanced respiration due to the application of BiPAP can improve the performance of autonomous nervous and cardiovascular systems, in terms of HRV. Moreover, it is suggested to consider some HRV parameters to control the cardiovascular side-effects of OHS and confine the resulting mortality rate in long term.

Measurement of heart rate variability can reveal autonomic nervous system function. Changes in heart rate variability can be associated with disease severity, risk of complications, and prognosis. We aimed to investigate the prognostic value of heart rate variability measurements in patients with moderate-to-severe traumatic brain injury after decompression surgery. We conducted a prospective study of 80 patients with traumatic brain injury after decompression surgery using a noninvasive electrocardiography device for data collection. Assessment of heart rate variability parameters included the time and frequency domains. The correlations between heart rate variability parameters and one-year mortality and functional outcomes were analyzed. Time domain measures of heart rate variability, using the standard deviation of the RR intervals and the square root of the mean squared differences of successive RR intervals, were statistically significantly lower in the group of patients with unfavorable outcomes and those that died. In frequency domain analysis, very low-frequency and total power were significantly higher in patients with favorable functional outcomes. High-frequency, low-frequency, and total power were statistically significantly higher in patients who survived for more than one year. Multivariate analysis using a model combining age and the Glasgow Coma Scale score with variables derived from heart rate variability substantially improved the prognostic value for predicting long-term outcome. These findings reinforced the concept that traumatic brain injury impacts the brain-heart axis and cardiac autonomic modulation even after decompression surgery, and variables derived from heart rate variability may be useful predictors of outcome.

Heart rate variability (HRV) has been used as an indicator of autonomic nervous system activity. These HRV measurements have also provided a promising research tool for studying the overtraining syndrome. PURPOSE: To examine the influence of increased volume of aerobic training on HRV, self reported feelings of exertion, and recovery among young endurance athletes. METHODS: Seventeen trained endurance athletes (aged 18–20) participated in this study. During a 5-day training camp, the total time used for aerobic training was gradually increased from 1–1 hours to 2–3 hours per day. In the first and last morning of the training camp the athletes performed two active orthostatic tests (AOT) from either supine or sitting position to standing position. RR-data were recorded with Polar VNV heart rate monitors (Polar Electro, Kempele, Finland) and analyzed with Polar Precision Performance 2.1 Software. Every morning the athletes filled in a questionnaire on the feelings of exertion and recovery during the previous 24 hours. In the first and last evening a 5km running test at set submaximal heart rate was performed. RESULTS: The changes in HRV in AOT during the training camp were greater in sit-stand test than in sup-stand test. Significant decrease in sitting and standing heart rate and increase in sitting and standing high frequency power (HFP) from the first to the last morning were found. The results showed also a significant increase in the feelings of physical exertion and decrease in the feelings of recovery. Average time in the running test was shorter, and the rated physical exertion (RPE) after the running test was higher in the last as compared to the first evening. CONCLUSION: These results suggest higher parasympathetic tone at the end of the training camp. Average speed in the running test (5km) at set submaximal heart rate increased, suggesting short-term training effect in five days. In contrast to the HRV changes, increased RPE during the running test, increased physical exertion and compromised recovery feelings suggested overreaching. AOT from sitting to standing position seems to be more sensitive to indicate changes in HRV than the traditional AOT from supine to standing position.

Morbidity and mortality in response to sepsis may be dependent on clock time for the initiation of sepsis. Endotoxaemia, an experimental model for systemic inflammation, induces alterations in sympatico-vagal balance in the autonomic nervous system (ANS). The activity of sympathetic and parasympathetic activity can be estimated by measuring heart rate variability (HRV). Based on the intimate link between ANS and the inflammatory response, we hypothesized, that HRV changes seen during endotoxaemia would be different based on time of the day the endotoxaemia is initiated. We investigated day/night variation in endotoxaemia-induced changes in HRV. A randomized, crossover study with 12 healthy men (age 18-31) was conducted. Endotoxaemia were induced by lipopolysaccharide (LPS) endotoxin 0.3 ng/kg b.w. in two visits (day visit and night visit). At the day visit, endotoxaemia were induced at 12:00 h, and at the night visit it was induced at 24:00 h. Holter recordings were started 1 h before administration of LPS, and continued for 10 h. Time-domain and frequency-domain parameters of HRV were analysed. A total of nine persons finished the study with valid recordings. Endotoxaemia at both night and day resulted in a significant depression in HRV parameters high-frequency power (HF), low-frequency power (LF), standard deviation of normal-to-normal (NN) intervals, root mean square of successive differences and proportion of NN50 divided by total number of NNs (P<0.001). The ratio LF/HF and mean heart rate significantly increased by endotoxaemia (P<0.001). At night-time endotoxaemia, a more pronounced depression of LF, HF and SDNN (P<0.01) and a more pronounced increase in the ratio of LF/HF and mean heart rate (P<0.01) occurred compared with day-time endotoxaemia. Endotoxaemia induced changes in HRV exhibit a day-night difference. This difference may have clinical consequences in patients with sepsis.

Heart rate variability (HRV) correlates well with a person's overall physiological function. Clinically, HRV is successfully used in acute care to identify impending infections, but little is known about its potential in the management of chronic diseases like cognitive decline/dementia. The aim of this study was to identify the best available knowledge about HRV in cognitively impaired populations that might be applied to improve clinical practice in community settings. We conducted a systematic literature search in PubMed, Embase, and Cochrane databases published from January 2009 to August 2022. Eligible studies were selected using Covidence and each study underwent qualitative assessment using the Mixed Method Appraisal Tool. At each stage of selection, each study was reviewed independently by two members of the team, and any disputes were discussed along the way. The literature identified that the brain regions controlling HRV are also those affected by dementias of Alzheimer's type (AD) and Lewy body types (DLB). HRV was impaired in both types, with DLB showing greater impairment in all HRV parameters compared to AD. No studies explored the temporal changes of HRV or its use in the clinical management of people with cognitive impairment (CI). The current lack of standardization of HRV recording and analysis limits its use in clinical practice. HRV may emerge as a potentially useful tool to identify people with early/preclinical memory impairment and help to differentiate AD from DLB. Longitudinal HRV measurement is emerging as a useful way to monitor disease progression and treatment response, and continuous HRV measurement may prove useful in the early identification of sepsis and its complications in patients no longer able to communicate their illness experiences.

Studies have assessed changesin autonomic variables in terms of heart rate variability (HRV) during meditation, but their results have been conflicting. Recently, Telles and colleagues’ excellent study 1 compared changes in HRV measures during the first four meditative states—cancalata (random thinking), ekagrata (nonmeditative focusing), dharana (meditative focusing), and dhyana (effortless meditation)— described in traditional yoga texts. Their results revealed that the discrepancy in changes in HRV measures might be due to the different stages. At the end of the Discussion section, the authors mention the ultimate state in yoga, samadhi, which manifests with breath suspension. They did not explore this advancedmeditativestateintheirstudy.Therefore,wewould like to share our results about changes in HRV measures during breath suspension. We collected and compared HRV measures in time and frequency domains, along with heart rate and blood pressure, during random thinking, breath meditation, and the advanced meditative stage with breath suspension in 10 meditative sessions conducted by an experienced meditator. The results (Table 1) show that none of HRV measures of time and frequency domains differed significantly during meditation. In contrast, heart rate and systolic blood pressure reliably decreased as meditation advanced. Because the meditation technique used in this study is close to meditative focusing, the results are concordant with the dharana state described in Telles and colleagues’ study. By using a device to monitor the chest circumstance of the meditator, the current study confirmed that the timing of breath suspension coincided with the subjective experience of breath suspension, complete quiescence, and absence of self-boundary. HRV measures, on the other hand, did not concord with the subjective experience of pure quiescence. Because other authors have argued that HRV is not an index of autonomic control of the circulation, 2 whether HRV can be an ideal index of sympathetic or parasympathetic activities remains questionable. According to the current results, the variations of HRV measures, manifested as the ratio of standard deviation to mean, are much greater than those of heart rate and blood pressure. This has also been shown in previous studies. 1,3,4 According to this view, HRV measures cannot be accurate indexes. The current results suggest that heart rate itself is a better HRV measure for meditation and agree with findings from Mukherjee et al. 5 These authors examined the sensitivity to mental effort and reliability of various HRV measures. Their