HYPNOTIZABILITY AND PAIN MODULATION: A Body-Mind Perspective.

The study investigated whether the cardiac activity and cognitive-emotional traits sustained by the behavioral inhibition/activation system (BIS/BAS) may contribute to hypnotizability-related pain modulation. Nociceptive stimulation (cold-pressor test) was administered to healthy participants with high (highs) and low (lows) hypnotizability in the presence and absence of suggestions for analgesia. Results showed that heart rate increased abruptly at the beginning of nociceptive stimulation in all participants.

A new method for QRS complex detection in multichannel ECG: Application to self-monitoring of fetal health.

This paper proposes a new approach for QRS complex detection in multichannel ECG and presents its application to fetal QRS (fQRS) detection in signals acquired from maternal abdominal leads. The method exploits the characteristics of pseudo-periodicity and time shape of QRS, it consists of devising a quality index (QI) which synthesizes these characteristics and of finding the linear combination of the acquired ECGs, which maximizes this QI. In the application for fQRS detection two QIs are devised, one QI (mQI) for maternal ECG (mECG) and one QI (fQI) for fetal ECG (fECG).

Paradoxical response to an emotional task: trait characteristics and heart-rate dynamics.

The present study evaluated the heart-rate dynamics of subjects reporting decreased (responders) or paradoxically increased relaxation (nonresponders) at the end of a threatening movie. Heart-rate dynamics were characterized by indices extracted through recurrence quantification analysis (RQA) and detrended fluctuation analysis (DFA). These indices were studied as a function of a few individual characteristics: hypnotizability, gender, absorption, anxiety, and the activity of the behavioral inhibition and activation systems (BIS/BAS).

An efficient unsupervised fetal QRS complex detection from abdominal maternal ECG.

Non-invasive fetal heart rate is of great relevance in clinical practice to monitor fetal health state during pregnancy. To date, however, despite significant advances in the field of electrocardiography, the analysis of abdominal fetal ECG is considered a challenging problem for biomedical and signal processing communities. This is mainly due to the low signal-to-noise ratio of fetal ECG and difficulties in cancellation of maternal QRS complexes, motion and electromyographic artefacts.

The role of wearable sensors and wireless technologies for the assessment of heart rate variability in anorexia nervosa.

Purpose: Bradycardia and abnormal cardiac autonomic function are related to increased mortality in anorexia nervosa (AN). The aim of this study was to assess heart rate (HR) and HR variability of young adolescents with AN as compared to controls by means of wearable sensors and wireless technologies.

Method: The ECG signal was recorded in 27 AN girls and 15 healthy girls at rest using a wearable chest strap.

Hypnotizability modulates the cardiovascular correlates of subjective relaxation.

Mean values and the spectral variability of heart rate (HRV), blood pressure, and skin blood flow were studied in high and low hypnotizable subjects during simple relaxation. Similar subjective relaxation was reported by highs and lows. A parasympathetic prevalence (indicated by a higher High-Frequency component of HRV and a lower High/Low-Frequency ratio) and lower renin-angiotensin activity (indicated by a lower Very-Low-Frequency component of HRV) could be attributed to highs with respect to lows.

Watching neutral and threatening movies: subjective experience and autonomic responses in subjects with different hypnotizability levels.

Subjects with high hypnotizability scores (Highs) have been considered more prone to experience negative affect and more vulnerable to its autonomic effects with respect to low hypnotizable individuals (Lows). The aim of the study was to analyze the subjective experience, tonic skin conductance (SC), respiratory frequency (RF), heart rate (HR) and heart rate variability (HRV) of healthy Highs and Lows during a long-lasting, emotionally neutral task (Session R, 46 subjects) and a moderately threatening one (Session T, 35 subjects). At the end of the relaxing Session R, all participants reported an increased relaxation.

Cardiovascular and respiratory correlates of deep nociceptive stimulation, suggestions for analgesia, pain imagery and cognitive load as a function of hypnotizability.

Hypnotizability is a cognitive trait modulating some physiological responses to cognitive and physical stimulation also in the normal awake state and in the absence of specific suggestions. Aim of the study was the characterization of the cardiovascular correlates of deep pain induced by nociceptive pressor stimulation without (PAIN) and with (AN) suggestions for analgesia, pain imagery/perception (IM) and mental computation (MC) in not hypnotized highly (Highs) and low (Lows) hypnotizable healthy subjects of both genders. The subjective experience of pain intensity, relaxation and task related fatigue were measured through a structured interview.

Modulation of the postural effects of cognitive load by hypnotizability.

Aim of the experiment was to study whether cognitive load affects postural control more in low (Lows) than in highly hypnotizable (Highs) subjects due to the latter's greater attentional abilities. Standing Highs and Lows underwent an experimental session (closed eyes) consisting of a basal condition and of mental computation in an easy (stable support) and a difficult (unstable support) postural condition. Variability [standard deviation (SD)] and complexity [sample entropy (SampEn)] of the movement of the centre of pressure (CoP), its mean velocity (Velocity), the area swept by the CoP (Area) and the ratio between the CoP trajectory length and area [length for surface (LFS)] were measured.

Heart-rate control during pain and suggestions of analgesia without deliberate induction of hypnosis.

Heart rate and heart-rate variability (HRV) were studied through a set of different methods in high (highs) and low hypnotizable subjects (lows) not receiving any deliberate hypnotic induction in basal conditions (simple relaxation) and during nociceptive-pressor stimulation with and without suggestions of analgesia. ANOVA did not reveal any difference between highs and lows for heart rate and for the HRV indexes extracted from the series of the interbeat intervals (RR) of the ECG in the frequency (spectral analysis) and time domain (standard deviation, Poincare plot) in both basal and stimulation conditions. Factors possibly accounting for the results and likely responsible for an underestimation of group differences are discussed.

Hypnotizability-dependent modulation of the changes in heart rate control induced by upright stance.

Subjects with high (Highs) and low (Lows) susceptibility to hypnosis show differences in the sensory-motor integration for postural control and in the cardiovascular response to stress and experimental pain. Aim of the experiment was to assess whether the cardiac response to gravity-related stimulation depending on changes in the body position were different in the two groups. Thus, heart rate (HR) and heart rate variability (HRV) were evaluated in sitting and upright position in Highs and Lows.

Improved integrate-and-fire model for rsa.

A simple operational model of heart rate variability is described, accounting in particular for the respiratory sinus arrhythmia, and is fitted to some interbeat interval sequences recorded from normal subjects at rest. The model performance is evaluated using a test based on the nonlinear prediction approach. Moreover, a short comparative account of two similar models described in the literature is given.

Cardiac resynchronization therapy and phase resetting of the sinoatrial node: a conjecture.

Congestive heart failure is a severe chronic disease often associated with disorders that alter the mechanisms of excitation-contraction coupling that may result in an asynchronous left ventricular motion which may further impair the ability of the failing heart to eject blood. In recent years a therapeutic approach to resynchronize the ventricles (cardiac resynchronization therapy, CRT) has been performed through the use of a pacemaker device able to provide atrial-based biventricular stimulation. Atrial lead senses the spontaneous occurrence of cells depolarization and sends the information to the generator which, in turn, after a settled delay [atrioventricular (AV) delay], sends electrical impulses to both ventricles to stimulate their synchronous contraction.

Nonlinear indices of heart rate variability in chronic heart failure patients: redundancy and comparative clinical value.

Aims: We aimed to assess the mutual interrelationships and to compare the prognostic value of a comprehensive set of nonlinear indices of heart rate variability (HRV) in a population of chronic heart failure (CHF) patients.

Methods And Results: Twenty nonlinear HRV indices, representative of symbolic dynamics, entropy, fractality-multifractality, predictability, empirical mode decomposition, and Poincaré plot families, were computed from 24-hour Holter recordings in 200 stable CHF patients in sinus rhythm (median age [interquartile range]: 54 [47-58] years, LVEF: 23 [19-28]%, NYHA class II-III: 88%). End point for survival analysis (Cox model) was cardiac death or urgent transplantation.

Heart rate variability in subjects with different hypnotic susceptibility receiving nociceptive stimulation and suggestions of analgesia.

The aim of the present study was to investigate the possible hypnotizability-related modulation of heart activity during nociceptive stimulation (pressor pain) and during nociceptive stimulation associated with the suggestion of analgesia in not hypnotized healthy individuals with a high (Highs) and a low (Lows) hypnotic susceptibility. ECG and respirogram were recorded. Standard time and frequency domain indexes were evaluated, together with the sd1 and sd2 values of the Poincaré plot over the RR series.

Clinical correlates of non-linear indices of heart rate variability in chronic heart failure patients.

We assessed the clinical correlates of a comprehensive set of non-linear heart rate variability (HRV) indices computed from 24-h Holter recordings for 200 stable chronic heart failure (CHF) patients [median age (lower quartile, upper quartile) 54 (47, 58) years, LVEF 23% (19%, 28%)]. A total of 19 non-linear indices belonging to six major families, namely symbolic dynamics, entropy, empirical mode decomposition, fractality-multifractality, unpredictability and Poincaré plots, were considered. Most indices showed a significant association with ejection fraction and with the severity of symptoms, while only two (one each from the fractality and Poincaré plot families) showed an association with aetiology.

Revisiting the potential of time-domain indexes in short-term HRV analysis.

In the context of HRV analysis, we evaluated the information content of two measures that can easily be derived from the classical RR time-domain indexes. The two measures are: 1) the ratio sd/rmssd, where sd is the RR standard deviation and rmssd is the root mean square of squared differences of consecutive RR beats; and 2) the ratio sd2/sd1, where sd2 and sd1 are extracted from the Poincaré plot and represent the transversal and longitudinal dispersion of the cloud of points (RR(i),RR(i)(+1)). We compared the performance of the two measures with that of the classical LF/HF ratio in a group of healthy subjects who underwent a 70 degrees upright tilt test.

A minimal model for the respiratory sinus arrhythmia.

The cardiac and respiratory rhythms in humans are known to be coupled by several mechanisms. In particular, the first rhythm is deeply modulated by the second. In this report we propose a simple operational model for heart rate variability which, taking such modulation into account, reproduces the main features of some experimental sequences of RR intervals recorded from healthy subjects in the resting condition.

Long- and short-time analysis of heartbeat sequences: correlation with mortality risk in congestive heart failure patients.

We analyze RR heartbeat sequences with a dynamic model that satisfactorily reproduces both the long- and the short-time statistical properties of heart beating. These properties are expressed quantitatively by means of two significant parameters, the scaling delta concerning the asymptotic effects of long-range correlation, and the quantity 1-pi establishing the amount of uncorrelated fluctuations. We find a correlation between the position in the phase space (delta, pi) of patients with congestive heart failure and their mortality risk.

Head-down bed rest reduces the breathing rate short-term variability in subjects with orthostatic intolerance.

Orthostatic intolerance is the most serious symptom of cardiovascular deconditioning induced by microgravity. We have showed that in symptomatic subjects the baroreflex control of sinus node is affected by short term simulated microgravity. At present the influence of the respiration on the cardiovascular system in this condition is not clear.

Influence of progressive central hypovolemia on Hölder exponent distributions of cardiac interbeat intervals.

The purpose of the study was to determine the dependency of the statistical properties of the R to R interval (RRI) time series on progressive central hypovolemia with lower body negative pressure. Two data-processing techniques based on wavelet transforms were used to determine the change in the nonstationary nature of the RRI time series with changing negative pressure. The results suggest that autonomic neural mechanism driving cardiac interbeat intervals during central hypovolemia go through various levels of multifractality, as determined by Hölder exponent distributions.

Mutual information detects a decreased interdependence between RR and SAP in orthostatic intolerance after microgravity condition.

Orthostatic intolerance is the most serious symptom of cardiovascular deconditioning induced by microgravity. However, the exact mechanisms underlying these alterations have not been completely clarified. Several methods for studying the time series of systolic arterial pressure and RR interval have been proposed both in the time and in the frequency domain.

Effect of 4 hours HD -6 degrees on heart rate variability in symptomatic and non symptomatic subjects.

Orthostatic intolerance is the most serious symptom of cardiovascular deconditioning induced by microgravity exposure. In fact the neural control mechanisms of the cardiovascular system are significantly affected by this condition. Non-invasive measurement of Heart Rate Variability (HRV) have been used as a valuable tool to characterize the ability of neuroendocrine regulatory systems to modulate the cardiovascular function by analyzing the spontaneous fluctuations of arterial pressure and heart period on a beat-to-beat basis.

Average magnitude of heartbeat fluctuations in healthy subjects after exposure to 4 hours head down bed rest.

Orthostatic intolerance, induced by microgravity exposure, has been hypothesized to be related to a disorder of the autonomic control of the cardiovascular system. Non-invasive measurement of Heart Rate Variability (HRV) have been used as a valuable tool to characterize the ability of the autonomic system to modulate the cardiovascular function by analyzing the spontaneous fluctuations of arterial pressure and heart period on a beat-to-beat basis. Concerning this, conflicting results have been reported on the heart rate and blood pressure variability responses during exposure to microG.