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The described application of granular computing is motivated because cardiovascular disease (CVD) remains a major killer globally. There is increasing evidence that abnormal respiratory patterns might contribute to the development and progression of CVD. Consequently, a method that would support a physician in respiratory pattern evaluation should be developed. Group decision-making, tri-way reasoning, and rough set–based analysis were applied to granular computing. Signal attributes and anthropomorphic parameters were explored to develop prediction models to determine the percentage contribution of periodic-like, intermediate, and normal breathing patterns in the analyzed signals. The proposed methodology was validated employing k-nearest neighbor (k-NN) and UMAP (uniform manifold approximation and projection). The presented approach applied to respiratory pattern evaluation shows that median accuracies in a considerable number of cases exceeded 0.75. Overall, parameters related to signal analysis are indicated as more important than anthropomorphic features. It was also found that obesity characterized by a high WHR (waist-to-hip ratio) and male sex were predisposing factors for the occurrence of periodic-like or intermediate patterns of respiration. It may be among the essential findings derived from this study. Based on classification measures, it may be observed that a physician may use such a methodology as a respiratory pattern evaluation-aided method.

This paper describes a novel way to measure, process, analyze, and compare respiratory signals acquired by two types of devices: a wearable sensorized belt and a microwave radar-based sensor. Both devices provide breathing rate readouts. First, the background research is presented. Then, the underlying principles and working parameters of the microwave radar-based sensor, a contactless device for monitoring breathing, are described. The breathing rate measurement protocol is then presented, and the proposed algorithm for octave error elimination is introduced. Details are provided about the data processing phase; specifically, the management of signals acquired from two devices with different working principles and how they are resampled with a common processing sample rate. This is followed by an analysis of respiratory signals experimentally acquired by the belt and microwave radar-based sensors. The analysis outcomes were checked using Levene’s test, the Kruskal–Wallis test, and Dunn’s post hoc test. The findings show that the proposed assessment method is statistically stable. The source of variability lies in the person-triggered breathing patterns rather than the working principles of the devices used. Finally, conclusions are derived, and future work is outlined.

Hyperglycemia is the major factor underlying vascular complications of diabetes. Unfortunately, improved glycemia control is frequently accompanied by an increased risk of hypoglycemia. The aim of the study was to assess the relationship between hemoglobin A1c (HbA1c) and 1-week Continuous Glucose Monitoring (CGM) data in long-standing type 1 diabetes (T1DM).We recruited 58 subjects with long-standing T1DM consecutively enrolled to the study. Each patient underwent a 1-week CGM and laboratory profile at baseline. Subjects were divided into three subgroups according to baseline HbA1c tertiles: T1 7.1%, T2 = 7.1-8.0%, and T3 8.0%.T1 patients were characterized by the longest time in range (66% of a week), whereas T3 patients experienced hyperglycemia in50% time of the week. T1 patients were noted to have 25% of nighttime with glycemia3.9 mmol/L (8% with glycemia2.8 mmol/L). Most recent HbA1c closely reflected 10-years mean HbA1c values (R = 0.83; P 0.0001).(1) Long-term diabetes control (10 years HbA1c mean) is a strong predictor of the current HbA1c levels. (2) Current and historical HbA1c levels are closely linked to CGM-derived glycemia. (3) Risk of clinically significant hypoglycemia negatively correlates with HbA1c. (4) HbA1c 8.0% is associated with unsatisfactorily low (44%) time in range.

Heart rate variability (hrv) is a physiological phenomenon of the variation in the length of the time interval between consecutive heartbeats. In many cases it could be an indicator of the development of pathological states. The classical approach to the analysis of hrv includes time domain methods and frequency domain methods. However, attempts are still being made to define new and more effective hrv assessment tools. Persistent homology is a novel data analysis tool developed in the recent decades that is rooted at algebraic topology. The Topological Data Analysis (TDA) approach focuses on examining the shape of the data in terms of connectedness and holes, and has recently proved to be very effective in various fields of research. In this paper we propose the use of persistent homology to the hrv analysis. We recall selected topological descriptors used in the literature and we introduce some new topological descriptors that reflect the specificity of hrv, and we discuss their relation to the standard hrv measures. In particular, we show that this novel approach provides a collection of indices that might be at least as useful as the classical parameters in differentiating between series of beat-to-beat intervals (RR-intervals) in healthy subjects and patients suffering from a stroke episode.

Respiration and heart rate continuously interact, and in the following, we are looking for variations in RR-intervals, systolic, and diastolic blood pressure caused by different phases of breathing. We propose a data-based model of interaction in the cardio-respiratory system, which is driven by breathing phases. The model reveals the desired properties of RR, SBP, and DBP signals, and is a promising starting point for a new data-based stochastic model of the cardio-respiratory system.

We evaluate the usefulness of persistent homology in the analysis of heart rate variability. In our approach we extract several topological descriptors characterising datasets of RR-intervals, which are later used in classical machine learning algorithms. By this method we are able to differentiate the group of patients with the history of transient ischemic attack and the group of hypertensive patients.

Objective: U-shaped patterns, characteristic periods of time observed in tachograms, are a specific subgroup among very low frequency components characterized by relatively short periods of smooth accelerations followed by decelerations of heart rhythm. In this study, we characterize this phenomenon and its effect on heart rate variability (HRV) parameters. Approach: We calculated linear (the mean and standard deviation of RR intervals, RMSSD, pNN50 and the power of the frequency components) and nonlinear (V0, V1 and V2 Porta’s symbolic analysis, Shannon and Sample entropy, Guzik’s and Porta’s asymmetry indexes, the exponents α1 and α2 of detrended fluctuation analysis and the Hurst surface h(q,s) of multiscale multifractal analysis (MMA)) HRV parameters for 65 RR interval night-time series (39 females, 37.5(11.3) years old and 26 males, 41.7(16.5) years old; all without organic heart diseases). All parameters were calculated for original data and for the three kinds of test data in which the following parts of the time series were replaced by 1/f noise: (A) the U-shape patterns annotated in a given data set, (B) randomly chosen windows of similar size as the U-shaped patterns, (C) acceleration-deceleration events shorter than U-shaped patterns. Main results: We found that the U-shaped patterns, as the most persistent structures in RR night-time intervals series, affect the long-range correlation properties (measured by α2). We also found that the U-shaped patterns importantly strictly affect the shape of h(q,s) surface at different scales s. Removing the U-shaped patterns results in the shape of the h(q,s) surface losing the properties characteristic for healthy heart rhythm. The largest quantitative effect of U-shaped patterns was obtained for the power of the VLF component. The mean percentage difference of the VLF component between the original data and the A to C type test data were 19.4%, −4.3% and 5.3%, respectively. Significance: Although percentage contribution of U-shaped patterns is small compared to the whole night-time series (on the average 3.1%(1.7%) with a standard deviation of 1.7%), these patterns have a considerable impact on the HRV parameters describing the VLF, persistency, nonlinear correlations and multifractal properties.

Context We have summarized key studies assessing the epidemiology, mechanisms, and consequences of cognitive dysfunction (CD) in type 1 diabetes. Evidence synthesis In a number of studies, the severity of CD in type 1 diabetes was affected by the age of onset and duration, and the presence of proliferative retinopathy and autonomic neuropathy. Diabetes-related CD has been observed, not only in adults, but also in children and adolescents. Most neuroimaging studies of patients with type 1 diabetes did not show any differences in whole brain volumes; however, they did reveal selective deficits in gray matter volume or density within the frontal, posterior, and temporal cortex and subcortical gray matter. Studies of middle-age adults with long-standing type 1 diabetes using diffusion tensor imaging have demonstrated partial lesions in the white matter and decreased fractional anisotropy in posterior brain regions. The mechanisms underlying diabetes-related CD are very complex and include factors related to diabetes per se and to diabetes-related cardiovascular disease and microvascular dysfunction, including chronic hyperglycemia, hypoglycemia, macro- and microvascular disease, and increased inflammatory cytokine expression. These mechanisms might contribute to the development and progression of both vascular dementia and Alzheimer disease. Conclusions Higher rates of CD and faster progression in type 1 diabetes can be explained by both the direct effects of altered glucose metabolism on the brain and diabetes-related cardiovascular disease. Because the presence and progression of CD significantly worsens the quality of life of patients with diabetes, further multidisciplinary studies incorporating the recent progress in both neuroimaging and type 1 diabetes management are warranted to investigate this problem.

Causal relationships are important to understand the dynamics of coupled processes and, moreover, to influence or control the effects by acting on the causes. Among the different approaches to determine cause-effect relationships and, in particular, coupling directions in interacting random or deterministic processes, we focus in this paper on information-theoretic measures. So, we study in the theoretical part the difference between directionality indicators based on transfer entropy as well as on its dimensional reduction via transcripts in algebraic time series representations. In the applications we consider specifically the lowest dimensional case, i.e., 3-dimensional transfer entropy, which is currently one of the most popular causality indicators, and the (2-dimensional) mutual information of transcripts. Needless to say, the lower dimensionality of the transcript-based indicator can make a difference in practice, where datasets are usually small. To compare numerically the performance of both directionality indicators, synthetic data (obtained with random processes) and real world data (in the form of biomedical recordings) are used. As happened in previous related work, we found again that the transcript mutual information performs as good as, and in some cases even better than, the lowest dimensional binned and symbolic transfer entropy, the symbols being ordinal patterns.

Purpose: In the course of hypertension, left ventricular hypertrophy and diastolic dysfunction develop very often and may progress toward heart failure. The aim of the study was to analyze the rela...

Objective The head-up tilt (HUT) test, which provokes transient dynamical alterations in the regulation of cardiovascular system, provides insights into complex organization of this system. Based on signals with heart period intervals (RR-intervals) and/or systolic blood pressure (SBP), differences in the cardiovascular regulation between vasovagal patients (VVS) and the healthy people group (CG) are investigated. Approach Short-term relations among signal data represented symbolically by three-beat patterns allow to qualify and quantify the complexity of the cardiovascular regulation by Shannon entropy. Four types of patterns: permutation, ordinal, deterministic and dynamical, are used, and different resolutions of signal values in the the symbolization are applied in order to verify how entropy of patterns depends on a way in which values of signals are preprocessed. Main results At rest, in the physiologically important signal resolution ranges, independently of the type of patterns used in estimates, the complexity of SBP signals in VVS is different from the complexity found in CG. Entropy of VVS is higher than CG what could be interpreted as substantial presence of noisy ingredients in SBP of VVS. After tilting this relation switches. Entropy of CG occurs significantly higher than VVS for SBP signals. In the case of RR-intervals and large resolutions, the complexity after the tilt becomes reduced when compared to the complexity of RR-intervals at rest for both groups. However, in the case of VVS patients this reduction is significantly stronger than in CG. Significance Our observations about opposite switches in entropy between CG and VVS might support a hypothesis that baroreflex in VVS affects stronger the heart rate because of the inefficient regulation (possibly impaired local vascular tone alternations) of the blood pressure.

The aim of the study was to test the hypothesis that alterations in large arteries are associated with microvascular remodelling and decreased retinal capillary blood flow.The study group comprised of 88 patients with essential hypertension and 32 healthy controls. Retinal microcirculation was evaluated by scanning laser Doppler flowmetry. Macrovascular changes were assessed on the basis of arterial stiffness measurement (carotid-femoral pulse wave velocity), its hemodynamic consequences (central pulse pressure, augmentation pressure, augmentation index) and intima media thickness of common carotid artery.Pulse wave velocity was inversely correlated to mean retinal capillary blood flow in hypertensive patients (R = -0.32, p 0.01). This relationship remained significant in multivariate regression analysis after adjustment for age, sex, central systolic blood pressure (BP) and body mass index (β = -31.27, p 0.001). Lumen diameter (LD) of retinal arterioles was significantly smaller in hypertensive then normotensive subjects (79.4 vs. 83.8, p = 0.03). Central and brachial systolic, diastolic and mean BPs were significantly correlated with LD and outer diameter of retinal arterioles. The relationship between LD and central BPs remained significant in multivariate analysis (β = -0.15, p = 0.03 for cSBP; β = -0.22, p = 0.04 for cDBP; β = -0.21, p = 0.03 for cMBP). Moreover, in a subgroup with cardiac damage central and brachial pulse pressure were positively associated with retinal wall thickness, wall cross sectional area, and wall to lumen ratio.In conclusion, the study provides a strong evidence that microcirculation is coupled with macrocirculation not only in terms of structural but also functional parameters.

Supplemental Digital Content is available in the text, Objectives: Our study aimed at exploring structural and functional differences in the brain during higher cognitive processing between middle-aged hypertensive patients and controls matched for sex, age and years of education. Methods: Two groups of 20 patients took part in MRI examinations. This article reports the results of functional MRI during a Stroop color interference task and structural evaluations based on a modified Fazekas scale. Results: No intergroup differences were found in regards to the severity of white matter lesions (Mann–Whitney U test = 150.5, P > 0.1), nor from the task performance in the scanner (t(35) = 0.2, P > 0.1). However, brain activation patterns between patients and controls varied. Hypertensive patients involved significantly more cerebral areas during the processing, regardless of the task difficulty. Differences were found in 26 diverse regions of both primary and associative cortices (with a peak voxel located in the cuneus, Z = 6.94, P

Biological regulation is sufficiently complex to pose an enduring challenge for characterization of both its equilibrium and transient non-equilibrium dynamics. Two univariate but coupled observables, heart rate and systolic blood pressure, are commonly characterized in the benchmark example of the human cardiovascular regulatory system. Asymmetric distributions of accelerations and decelerations of heart rate, as well as rises and falls in systolic blood pressure, recorded in humans during a head-up tilt test provide insights into the dynamics of cardiovascular response to a rapid, controlled deregulation of the system’s homeostasis. The baroreflex feedback loop is assumed to be the fundamental physiological mechanism for ensuring homeostatic blood supply to distant organs at rest and during orthostatic stress, captured in a classical beat-to-beat autoregressive model of baroreflex by de Boer et al. (1987). For model corroboration, a multistructure index statistic is proposed, seamlessly evaluating the size spectrum of magnitudes of neural reflexes such as baroreflex, responsible for maintaining the homeostatic dynamics. The multistructure index exposes a distinctly different dynamics of multiscale asymmetry between results obtained from real-life signals recorded from healthy subjects and those simulated using both the classical and perturbed versions of the model. Nonlinear effects observed suggest the pronounced presence of complex mechanisms resulting from baroreflex regulation when a human is at rest, which is aggravated in the system’s response to orthostatic stress. Using our methodology of multistructure index, we therefore show a marked difference between model and real-life scenarios, which we attribute to multiscale asymmetry of non-linear origin in real-life signals, which we are not reproducible by the classical model.

Arterial hypertension negatively influences the peripheral auditory system, causing sensorineural hearing loss. Much less is known about the detrimental effects of hypertension on the central auditory functions.We tested 32 arterial hypertension patients and 32 age and sex-matched healthy volunteers with the expanded tonal audiometry (0.125-12.5 kHz), distortion product otoacoustic emissions (0.75-8 kHz), horizontal minimum audible angle test for eight azimuths with binaural stimulation and the random gap detection test.Peripheral hearing of the hypertensive patients was impaired in comparison with the controls within all audiometric frequencies (0.125-12.5 kHz) and within specific groups of frequencies. Distortion product otoacoustic emission results were significantly lower for frequencies 4 (P = 0.04) and 6 kHz (P 0.001). The sound localization ability in the horizontal minimum audible angle test was significantly worse in the hypertensive patients in the 0°, 45°, 90°, 135°, and 270° azimuth when the interaural pure tone average (0.5-1-2 kHz) was set less than 20 dB hearing level (P 0.05), and in the 0°, 90°, 225°, and 270°azimuth when the binaural pure tone average (0.5-1-2 kHz) was set 20 dB or less hearing level (P 0.05). Gap detection thresholds in the random gap detection test did not differ between the two groups.Arterial hypertension is independently related to the damage of the peripheral part of the auditory system resulting in high-frequency hearing loss. Hypertensive disturbances of central auditory processing are more discrete and concern the spatial hearing resolution.

We organized 10Kin1day, a pop-up scientific event with the goal to bring together neuroimaging groups from around the world to jointly analyze 10,000+ existing MRI connectivity datasets during a 3-day workshop. In this report, we describe the motivation and principles of 10Kin1day, together with a public release of 8,000+ MRI connectome maps of the human brain.

Objective:The aim of the study was to test the hypothesis if arterial stiffness is linked to reduction of retinal capillary blood flow and development of retinal microvascular remodelling.Design and method:The study group comprised of 88 patients with essential hypertension (n = 88, 54.3 ± 8.3 years

Objective:The aim of the study was to establish the relationship between structural and functional abnormalities of retinal microcirculation and cardiac damage defined as the presence of left ventricle hypertrophy and/or diastolic dysfunction.Design and method:The study consisted of 88 patients with

Previous studies reported that normobaric hyperoxia influences heart rate, arterial pressure, cardiac output and systemic vascular resistance, but the mechanisms underlying these changes are still not fully understood. Several factors are considered including degeneration of endothelium-derived nitric oxide by reactive oxygen species, the impact of oxygen-free radicals on tissues and alterations of autonomic nervous system function. Recently, new devices for the detailed non-invasive assessment of large and small arteries have been developed. Therefore, the aim of our study was to assess heart rate variability (HRV) as a potential indicator of autonomic balance and its relation to blood pressure and vascular properties during medical air (MAB) and 100% oxygen breathing (OXB) in healthy volunteers. In 12 healthy subjects we assessed heart rate and blood pressure variability, baroreflex sensitivity, respiratory frequency, common carotid artery diameter and its wall distensibility, as well as changes in the digital artery pulse waveform, stroke index and systemic vascular resistance during MAB and OXB. Mean and systolic blood pressure have increased significantly while digital pulse amplitude and carotid artery diameter were significantly lower during hyperoxia. Heart rate variability measures did not differ during MAB and OXB. However, the correlations between spectral HRV components and those hemodynamic parameters which have changed due to hyperoxia varied substantially during MAB (correlated significantly) and OXB (no significant correlations were noted). Our findings suggest that autonomic nervous system might not be the main mediator of the cardiovascular changes during 100% oxygen breathing in healthy subjects. It seems that the direct vascular responses are initial consequences of hyperoxia and other cardiovascular parameter alterations are secondary to them.

Background and purpose Heart rate variability (HRV) as a measure of autonomic function might provide prognostic information in ischemic stroke. However, numerous difficulties are associated with HRV parameters assessment and interpretation, especially in short-term ECG recordings. For better understanding of derived HRV data and to avoid methodological bias we simultaneously recorded and analyzed heart rate, blood pressure and respiratory rate. Methods Seventy-five ischemic stroke patients underwent short-term ECG recordings. Linear and nonlinear parameters of HRV as well as beat-to-beat blood pressure and respiratory rate were assessed and compared in patients with different functional neurological outcomes at 7th and 90th days. Results Values of Approximate, Sample and Fuzzy Entropy were significantly lower in patients with poor early neurological outcome. Patients with poor 90-day outcome had higher percentage of high frequency spectrum and normalized high frequency power, lower normalized low frequency power and lower low frequency/high frequency ratio. Low frequency/high frequency ratio correlated negatively with scores in the National Institutes of Health Stroke Scale and modified Rankin Scale (mRS) at the 7th and mRS at the 90th days. Mean RR interval, values of blood pressure as well as blood pressure variability did not differ between groups with good and poor outcomes. Respiratory frequency was significantly correlated with the functional neurological outcome at 7th and 90th days. Conclusion While HRV assessed by linear methods seems to have long-term prognostic value, complexity measures of HRV reflect the impact of the neurological state on distinct, temporary properties of heart rate dynamic. Respiratory rate during the first days of the stroke is associated with early and long-term neurological outcome and should be further investigated as a potential risk factor.

The recognition of all main features of a healthy heart rhythm (the so-called sinus rhythm) is still one of the biggest challenges in contemporary cardiology. Recently the interesting physiological phenomenon of heart rate asymmetry has been observed. This phenomenon is related to unbalanced contributions of heart rate decelerations and accelerations to heart rate variability. In this paper we apply methods based on the concept of ordinal pattern to the analysis of electrocardiograms (inter-peak intervals) of healthy subjects in the supine position. This way we observe new regularities of the heart rhythm related to the distribution of ordinal patterns of lengths 3 and 4.

Most random processes studied in nonlinear time series analysis take values on sets endowed with a group structure, e.g., the real and rational numbers, and the integers. This fact allows to associate with each pair of group elements a third element, called their transcript, which is defined as the product of the second element in the pair times the first one. The transfer entropy of two such processes is called algebraic transfer entropy. It measures the information transferred between two coupled processes whose values belong to a group. In this paper, we show that, subject to one constraint, the algebraic transfer entropy matches the (in general, conditional) mutual information of certain transcripts with one variable less. This property has interesting practical applications, especially to the analysis of short time series. We also derive weak conditions for the 3-dimensional algebraic transfer entropy to yield the same coupling direction as the corresponding mutual information of transcripts. A related issue concerns the use of mutual information of transcripts to determine coupling directions in cases where the conditions just mentioned are not fulfilled. We checked the latter possibility in the lowest dimensional case with numerical simulations and cardiovascular data, and obtained positive results.

Introduction Syncope is a common presentation of sinus node dysfunction (SND). Some patients who receive a permanent pacemaker due to SND do not benefit from it and further diagnostic workup leads to the diagnosis of vasovagal syncope (VVS). The aim of the study was to identify electrophysiological criteria that can be used for identification of patients with SND and concurrent VVS. Material and methods Transoesophageal atrial pacing (TAP) was performed in 100 patients divided into four groups depending on symptoms and TAP results. Standard electrophysiological parameters of sinus node function and their variability were obtained in the basal state and after pharmacological autonomic blockade (AB). Results Patients with concurrent SND and VVS had a greater variability of sinoatrial conduction time assessed by Strauss’ method than patients without incidents of syncope (83.2 ±53.9 vs. 34.1 ±19.6, 47.8 ±33.6 and 32.1 ±22.99). Apart from abnormal sinus node recovery time and second pause, patients with SND had bigger basal state variability of these parameters. In patients with SND and concurrent vasovagal syncope the variability of sinus node recovery time (SNRT), corrected SNRT (cSNRT) and second pause (IIP) decreased after autonomic blockade. Conclusions Patients with concurrent SND and VVS have distinct electrophysiological features – greater sinoatrial conduction time (SACT) variability and the decrease of SNRT, cSNRT and IIP variability after AB. However, further studies in larger study groups are needed to validate our findings. Transoesophageal atrial pacing is a useful procedure in patients with syncope, especially when the coexistence of more than one cardiac cause is suspected.