When Heart Beats Differently in Depression: Review of Nonlinear Heart Rate Variability Measures.

BACKGROUND: Disturbed heart dynamics in depression seriously increases mortality risk. Heart rate variability (HRV) is a rich source of information for studying this dynamics. This paper is a meta-analytic review with methodological commentary of the application of nonlinear analysis of HRV and its possibility to address cardiovascular diseases in depression. OBJECTIVE: This paper aimed to appeal for the introduction of cardiological screening to patients with depression, because it is still far from established practice. The other (main) objective of the paper was to show that nonlinear methods in HRV analysis give better results than standard ones. METHODS: We systematically searched on the web for papers on nonlinear analyses of HRV in depression, in line with PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) 2020 framework recommendations. We scrutinized the chosen publications and performed random-effects meta-analysis, using the esci module in jamovi software where standardized effect sizes (ESs) are corrected to yield the proof of the practical utility of their results. RESULTS: In all, 26 publications on the connection of nonlinear HRV measures and depression meeting our inclusion criteria were selected, examining a total of 1537 patients diagnosed with depression and 1041 healthy controls (N=2578). The overall ES (unbiased) was 1.03 (95% CI 0.703-1.35; diamond ratio 3.60). We performed 3 more meta-analytic comparisons, demonstrating the overall effectiveness of 3 groups of nonlinear analysis: detrended fluctuation analysis (overall ES 0.364, 95% CI 0.237-0.491), entropy-based measures (overall ES 1.05, 95% CI 0.572-1.52), and all other nonlinear measures (overall ES 0.702, 95% CI 0.422-0.982). The effectiveness of the applied methods of electrocardiogram analysis was compared and discussed in the light of detection and prevention of depression-related cardiovascular risk. CONCLUSIONS: We compared the ESs of nonlinear and conventional time and spectral methods (found in the literature) and demonstrated that those of the former are larger, which recommends their use for the early screening of cardiovascular abnormalities in patients with depression to prevent possible deleterious events.

Application of a Diagnostic Methodology of Cardiac Systems Based on the Proportions of Entropy in Normal Patients and with Different Pathologies.

INTRODUCTION: Dynamical systems theory, probability, and entropy were the substrate for the development of the diagnostic and predictive methodology of adult heart dynamics. OBJECTIVE: To apply a previously developed methodology from dynamical systems, probability, and entropy in both normal and pathological subjects. METHODS: Electrocardiographic records were selected from 30 healthy subjects and 200 with different pathologies, with a length of least 18 h. Numerical attractors from dynamical attractors and the probability of occurrence of ordered pairs of consecutive heart rates were built. A calculation of entropy and its proportions was performed and statistical analysis was conducted. RESULTS: The normal patients' heart dynamics were evaluated according to the methodology of entropy proportions, highlighting that there are differences in normal patients with different pathologies. There was maximal level of sensitivity, specificity, and diagnostic agreement. CONCLUSION: Proportional entropy constitutes a diagnostic and predictive method of heart systems, and may be useful as a tool to objectively diagnose and perform the follow-up of normal and pathological cases.

Caracterización matemática de dinámicas cardiacas neonatales normales a partir de la teoría de la probabilidad / Mathematical Characterization of Normal Neonatal Cardiac Dynamics Based on Probability Theory

Introducción: la dinámica cardiaca se ha evaluado desde teorías físico' matemáticas como la probabilidad y los sistemas dinámicos, lo que ha permitido desarrollar diagnósticos y predicciones de aplicación clínica. Objetivo: medir la probabilidad de distribuciones de frecuencias cardiacas (FC) neonatales normales, para hacer una caracterización matemática, objetiva y reproducible. Metodología: se analizaron diez dinámicas normales mediante registros continuos y holters, tomando los máximos y mínimos de FC por hora durante 21 horas. Se generaron rangos de 5 latmin, y se estableció cuántas frecuencias pertenecen a cada rango. Se analizaron las distribuciones obtenidas en el espacio de probabilidades para las frecuencias cardiacas, en busca de características matemáticas de normalidad para la dinámica cardiaca neonatal. Resultados: las probabilidades de los rangos evaluados variaron entre 0,02272 y 0,2826-, y en tres de los rangos, todas las dinámicas presentaron probabilidad mínima o cero. Conclusiones: se desarrolló una caracterización general de la dinámica cardiaca neonatal normal, objetiva y reproducible.

Background: Cardiac dynamics have been evaluated from physicah mathematical theories like probability and dynamícal Systems, allowing to developing diagnosis and dinical application predictions. Objective: To measure the probability of normal neonatal heart rates distribution, for doing a mathematical characterization, objective and reproducible. Methods: It have been analyzed 10 normal dynamics through continuous records and holters, taking máximum and mínimum valúes of heart rates per hour during 21 hours. Ranges of 5 beats/min were generated; obtained distributions in probability space for heart rates were analyzed, to search normality mathematical characteristics for neonatal cardiac dynamics. Results: The probabilities of the evaluated ranges varied between 0.02272 and 0.2826; also, in three of the ranges, all the dynamics showed a minimum probability or zero. Condusions: A general characterization, objective and reproductible, of normal neonatal cardiac dynamics, was developed.

Combining electroencephalographic activity and instantaneous heart rate for assessing brain-heart dynamics during visual emotional elicitation in healthy subjects.

Emotion perception, occurring in brain areas such as the prefrontal cortex and amygdala, involves autonomic responses affecting cardiovascular dynamics. However, how such brain-heart dynamics is further modulated by emotional valence (pleasantness/unpleasantness), also considering different arousing levels (the intensity of the emotional stimuli), is still unknown. To this extent, we combined electroencephalographic (EEG) dynamics and instantaneous heart rate estimates to study emotional processing in healthy subjects. Twenty-two healthy volunteers were elicited through affective pictures gathered from the International Affective Picture System. The experimental protocol foresaw 110 pictures, each of which lasted 10 s, associated to 25 different combinations of arousal and valence levels, including neutral elicitations. EEG data were processed using short-time Fourier transforms to obtain time-varying maps of cortical activation, whereas the associated instantaneous cardiovascular dynamics was estimated in the time and frequency domains through inhomogeneous point-process models. Brain-heart linear and nonlinear coupling was estimated through the maximal information coefficient (MIC). Considering EEG oscillations in theθband (4-8 Hz), MIC highlighted significant arousal-dependent changes between positive and negative stimuli, especially occurring at intermediate arousing levels through the prefrontal cortex interplay. Moreover, high arousing elicitations seem to mitigate changes in brain-heart dynamics in response to pleasant/unpleasant visual elicitation.

Live imaging and modeling for shear stress quantification in the embryonic zebrafish heart.

Hemodynamic shear stress is sensed by the endocardial cells composing the inner cell layer of the heart, and plays a major role in cardiac morphogenesis. Yet, the underlying hemodynamics and the associated mechanical stimuli experienced by endocardial cells remains poorly understood. Progress in the field has been hampered by the need for high temporal resolution imaging allowing the flow profiles generated in the beating heart to be resolved. To fill this gap, we propose a method to analyze the wall dynamics, the flow field, and the wall shear stress of the developing zebrafish heart. This method combines live confocal imaging and computational fluid dynamics to overcome difficulties related to live imaging of blood flow in the developing heart. To provide an example of the applicability of the method, we discuss the hemodynamic frequency content sensed by endocardial cells at the onset of valve formation, and how the fundamental frequency of the wall shear stress represents a unique mechanical cue to endocardial, heart-valve precursors.

Influence of plaque calcifications on coronary stent fracture: a numerical fatigue life analysis including cardiac wall movement.

Coronary stent fracture is still an unresolved issue in the field of minimally invasive cardiovascular interventions due to its high rate of incidence and uncertain clinical consequences. Recent studies, based on clinical data, proved that there are several factors which can be identified as independently responsible of coronary stent fracture. Among these, calcifications, which increase the local stiffness and heterogeneity of atherosclerotic plaques, seem to play a major role. From a mechanical point of view, stent fracture in coronary arteries is triggered by the cyclic loading of pulsatile blood pressure combined with the movement of cardiac wall. In this context, this study aims at simulating the stent expansion in a model of epicardial atherosclerotic coronary artery and correlating the effects of cyclic blood pressure and cardiac wall movement on the stent fatigue resistance. Two ideal cases of atherosclerotic plaques were modelled: the first one included a localised plaque calcification; the latter one did not include such calcification. Results of stress/strain and fatigue analyses confirmed the influence of the plaque calcification on potential fracture of the devices. In addition, the effects of cardiac wall movement were quantified as more dangerous causes of the stent fatigue fracture with respect to the internal blood pressure oscillations. In conclusion, this study demonstrates the increased risk of coronary stent fracture associated to the presence of localised plaque calcifications. This work also suggests the necessity of more realistic biomechanical models which takes into account the heterogeneity of atherosclerotic plaques in order to assess the mechanical performances of coronary stents.