Comparison of heart rate variability in supine, and left and right lateral positions

Analysis of nasal resistance regulation mechanism during postural changes in patients with obstructive sleep apnea by measuring heart rate variability

STUDY OBJECTIVES

Changes in nasal resistance (NR) during postural changes are influenced by venous filling pressure and autonomic nervous system mediation, and heart rate variability (HRV) can reflect changes in the autonomic nervous system. This study aimed to explore the regulatory mechanisms of NR in patients with obstructive sleep apnea (OSA) during postural changes.

METHODS

Healthy controls (apnea-hypopnea index < 5 events/h) and patients with OSA were recruited. NR and electrocardiogram data were collected in sitting, supine, left-lateral, and right-lateral postures. HRV parameters were obtained by analyzing the electrocardiogram data from each posture. Subgroups were divided according to sitting-supine NR changes, and HRV parameters were compared between different postures and groups/subgroups.

RESULTS

In total, 34 healthy controls and 39 patients with OSA (mean apnea-hypopnea index 34.34 ± 22.44 events/h) were recruited. During sitting-supine postural changes, the NR increased in the control group but did not change significantly in the OSA group. None of the autonomic nervous system-related HRV parameters changed significantly. After the groups were divided into NR-elevated and NR-unchanged subgroups, sympathetic activity-related HRV parameters were higher in the NR-unchanged subgroup but only statistically significant in the OSA group. When comparing the left and right postures, there was no significant change in NR; however, the OSA group had lower parasympathetic activity-related HRV parameters when in the right posture.

CONCLUSIONS

During postural changes from the sitting to supine positions, the total NR increases, and this increment is smaller in patients with OSA. This is likely due to overregulation of sympathetic activity, which may occur in patients with OSA.

CITATION

Shi Y, Lou H, Wang H, et al. Analysis of nasal resistance regulation mechanism during postural changes in obstructive sleep apnea patients by measuring heart rate variability. J Clin Sleep Med. 2023;19(4):643-650.

MITEA: A dataset for machine learning segmentation of the left ventricle in 3D echocardiography using subject-specific labels from cardiac magnetic resonance imaging

Segmentation of the left ventricle (LV) in echocardiography is an important task for the quantification of volume and mass in heart disease. Continuing advances in echocardiography have extended imaging capabilities into the 3D domain, subsequently overcoming the geometric assumptions associated with conventional 2D acquisitions. Nevertheless, the analysis of 3D echocardiography (3DE) poses several challenges associated with limited spatial resolution, poor contrast-to-noise ratio, complex noise characteristics, and image anisotropy. To develop automated methods for 3DE analysis, a sufficiently large, labeled dataset is typically required. However, ground truth segmentations have historically been difficult to obtain due to the high inter-observer variability associated with manual analysis. We address this lack of expert consensus by registering labels derived from higher-resolution subject-specific cardiac magnetic resonance (CMR) images, producing 536 annotated 3DE images from 143 human subjects (10 of which were excluded). This heterogeneous population consists of healthy controls and patients with cardiac disease, across a range of demographics. To demonstrate the utility of such a dataset, a state-of-the-art, self-configuring deep learning network for semantic segmentation was employed for automated 3DE analysis. Using the proposed dataset for training, the network produced measurement biases of -9 ± 16 ml, -1 ± 10 ml, -2 ± 5 %, and 5 ± 23 g, for end-diastolic volume, end-systolic volume, ejection fraction, and mass, respectively, outperforming an expert human observer in terms of accuracy as well as scan-rescan reproducibility. As part of the Cardiac Atlas Project, we present here a large, publicly available 3DE dataset with ground truth labels that leverage the higher resolution and contrast of CMR, to provide a new benchmark for automated 3DE analysis. Such an approach not only reduces the effect of observer-specific bias present in manual 3DE annotations, but also enables the development of analysis techniques which exhibit better agreement with CMR compared to conventional methods. This represents an important step for enabling more efficient and accurate diagnostic and prognostic information to be obtained from echocardiography.

High Altitude Affects Nocturnal Non-linear Heart Rate Variability: PATCH-HA Study

Background: High altitude (HA) exposure can lead to changes in resting heart rate variability (HRV), which may be linked to acute mountain sickness (AMS) development. Compared with traditional HRV measures, non-linear HRV appears to offer incremental and prognostic data, yet its utility and relationship to AMS have been barely examined at HA. This study sought to examine this relationship at terrestrial HA. Methods: Sixteen healthy British military servicemen were studied at baseline (800 m, first night) and over eight consecutive nights, at a sleeping altitude of up to 3600 m. A disposable cardiac patch monitor was used, to record the nocturnal cardiac inter-beat interval data, over 1 h (0200-0300 h), for offline HRV assessment. Non-linear HRV measures included Sample entropy (SampEn), the short (α1, 4-12 beats) and long-term (α2, 13-64 beats) detrend fluctuation analysis slope and the correlation dimension (D2). The maximal rating of perceived exertion (RPE), during daily exercise, was assessed using the Borg 6-20 RPE scale. Results: All subjects completed the HA exposure. The average age of included subjects was 31.4 ± 8.1 years. HA led to a significant fall in SpO₂ and increase in heart rate, LLS and RPE. There were no significant changes in the ECG-derived respiratory rate or in any of the time domain measures of HRV during sleep. The only notable changes in frequency domain measures of HRV were an increase in LF and fall in HFnu power at the highest altitude. Conversely, SampEn, SD1/SD2 and D2 all fell, whereas α1 and α2 increased (p < 0.05). RPE inversely correlated with SD1/SD2 (r = -0.31; p = 0.002), SampEn (r = -0.22; p = 0.03), HFnu (r = -0.27; p = 0.007) and positively correlated with LF (r = 0.24; p = 0.02), LF/HF (r = 0.24; p = 0.02), α1 (r = 0.32; p = 0.002) and α2 (r = 0.21; p = 0.04). AMS occurred in 7/16 subjects (43.8%) and was very mild in 85.7% of cases. HRV failed to predict AMS. Conclusion: Non-linear HRV is more sensitive to the effects of HA than time and frequency domain indices. HA leads to a compensatory decrease in nocturnal HRV and complexity, which is influenced by the RPE measured at the end of the previous day. HRV failed to predict AMS development.

Heart rate variability in multibacillar leprosy: Linear and nonlinear analysis

Objective

To evaluate the heart rate variability (HRV) in patients with multibacillary leprosy using dynamic linear and nonlinear analysis.

Material and methods

Twenty-one leprosy patients (mean age: 39.14 ±10.58 years) and 21 healthy subjects (mean age: 36.24 ± 12.64 years) completed the sample. Heart rate variability recording was performed by a Polar RS800 CX heart monitor during a period of 15 min in the supine position and 15 min in a sitting position. Analysis of HRV was performed by frequency domain from high frequency (HF) and low frequency (LF) spectral indexes in absolute and normalized units. The nonlinear analysis of HRV was calculated using symbolic analysis (0V%, 1V%, 2LV% and 2UV% indexes), Shannon entropy (SE) and normalized complexity index (NCI).

Results

Linear analysis: both groups showed higher HF values (p < 0.05) and smaller LF values (p < 0.05) in supine than in sitting position. The leprosy patients showed higher LF values (p < 0.05) and smaller HF values (p < 0.05) compared to the controls on supine position. Symbolic analysis: leprosy patients had higher 0V% values (p < 0.05), smaller 2LV% values (p < 0.05) and 2UV % values compared to healthy subjects on both positions. The 1V % had higher values (p < 0.05) for leprosy patients than for controls in the sitting position. The control subjects had smaller 0V % values (p < 0.05), and higher 2UV % values (p < 0.05) in the supine position compared to the sitting position. Leprosy patients had higher 2UV index values (p < 0.05) in the supine position compared to the sitting position. In the complexity analysis, leprosy patients had smaller SE and NCI values (p < 0.05) than the control in the supine position. There was no difference between the SE and NCI values of leprosy and the control subjects in the sitting position. The control subjects had higher SE and NCI values (p < 0.05) in the supine position than in the sitting position.

Conclusion

Leprosy patients had higher sympathetic modulation and smaller vagal modulation than controls, indicating less HRV and cardiac modulation with lower complexity. The control group displayed significant HRV differences in response to position changes while leprosy patients had fewer HRV differences after the same postural change. An analysis of HRV with linear and non-linear dynamics proved to be a reliable method and promising for the investigation of autonomic dysfunction in patients with multibacillary leprosy.

The Cardiac Sympathetic Nerve Activity in the Elderly Is Attenuated in the Right Lateral Decubitus Position

Objectives: The aim of this study was to evaluate the effect of the supine, left lateral decubitus, and right lateral decubitus positions on autonomic nervous activity in elderly adults by using spectral analysis of heart rate variability (HRV). Method: Forty-five adults aged 73.6 ± 5.7 years were enrolled. After lying in the supine position, all participants moved to the lateral decubitus positions in a random order and maintained the positions for 10 min, while electrocardiographic data were recorded to measure HRV. Results: The lowest heart rate continued for 10 min when participants were in the left lateral decubitus position compared with the other two positions (p < .001), while the HRV indexes remained unchanged. The low-frequency HRV to high-frequency HRV ratio (LF/HF) for the right lateral decubitus position was significantly lower than that for the other positions. Discussion: The right lateral decubitus position may attenuate sympathetic nerve activity in elderly adults.

Body position and cardio-respiratory variables in older people

What effect does body position have on cardio-respiratory variables in active older people? An experimental laboratory study was undertaken measuring heart rate, systolic and diastolic blood pressure and oxygen saturation when 26 active people aged 60 years and over adopted five standardized body positions. Measurements were taken every 2 min over a 10-min period in sitting, right side lying, left side lying, supine and supine with the head 20° below the level of the body. Rate pressure product and mean arterial pressure were calculated. Smoking history, medication use, health conditions and activity level were recorded. Height, weight and body fat were measured. Left and right side lying produced significantly lower diastolic and systolic blood pressure, rate pressure product and mean arterial pressure than supine with the head down. Excluding oxygen saturation mean values for all variables remained within recommended normal limits in all positions. Significant differences in cardio-respiratory variables occur when active older people change body position. Positioning as a treatment intervention appears safe in supine, side lying and sitting for this population. Head down supine position should be adopted with caution.

Effects of body position on autonomic regulation of cardiovascular function in young, healthy adults

Background

Analysis of rhythmic patterns embedded within beat-to-beat variations in heart rate (heart rate variability) is a tool used to assess the balance of cardiac autonomic nervous activity and may be predictive for prognosis of some medical conditions, such as myocardial infarction. It has also been used to evaluate the impact of manipulative therapeutics and body position on autonomic regulation of the cardiovascular system. However, few have compared cardiac autonomic activity in supine and prone positions, postures commonly assumed by patients in manual therapy. We intend to redress this deficiency.

Methods

Heart rate, heart rate variability, and beat-to-beat blood pressure were measured in young, healthy non-smokers, during prone, supine, and sitting postures and with breathing paced at 0.25 Hz. Data were recorded for 5 minutes in each posture: Day 1 – prone and supine; Day 2 – prone and sitting. Paired t-tests or Wilcoxon signed-rank tests were used to evaluate posture-related differences in blood pressure, heart rate, and heart rate variability.

Results

Prone versus supine: blood pressure and heart rate were significantly higher in the prone posture (p < 0.001). Prone versus sitting: blood pressure was higher and heart rate was lower in the prone posture (p < 0.05) and significant differences were found in some components of heart rate variability.

Conclusion

Cardiac autonomic activity was not measurably different in prone and supine postures, but heart rate and blood pressure were. Although heart rate variability parameters indicated sympathetic dominance during sitting (supporting work of others), blood pressure was higher in the prone posture. These differences should be considered when autonomic regulation of cardiovascular function is studied in different postures.