Increased short-term variability of the QT interval in professional soccer players: possible implications for arrhythmia prediction. by Csaba Lengyel, Andrea Orosz, Péter Hegyi, Zsolt Komka, Anna Udvardy, Edit Bosnyák, Emese Trájer, Gábor Pavlik, Miklós Tóth, Tibor Wittmann, Julius Gy Papp, András Varró, István Baczkó

“…The temporal instability of beat-to-beat heart rate and repolarization were characterized by the calculation of short-term variability of the RR and QT intervals. …”
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Blood Pressure Variability in Clinical Practice: Past, Present and the Future by Abu Baker Sheikh, Paul A. Sobotka, Ishan Garg, Jessilyn P. Dunn, Abdul Mannan Khan Minhas, Md Mobashir Hasan Shandhi, Jeroen Molinger, Barry J. McDonnell, Marat Fudim

“…Clinically, BP variability is classified into 4 main types on the basis of the duration of monitoring time: very‐short‐term (beat to beat), short‐term (within 24 hours), medium‐term (within days), and long‐term (over months and years). …”
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Using Complexity Metrics With R-R Intervals and BPM Heart Rate Measures by Sebastian eWallot, RIccardo eFusaroli, RIccardo eFusaroli, RIccardo eFusaroli, Kristian eTylen, Kristian eTylen, Kristian eTylen, Else-Marie eJegindø, Else-Marie eJegindø

“…In this article we compare linear and non-linear statistics on two prominent types of heart beat data, beat-to-beat intervals (R-R interval) and beats-per-minute (BPM). …”
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Accuracy of heart rate variability estimated with reflective wrist-PPG in elderly vascular patients by Christoph Hoog Antink, Yen Mai, Mikko Peltokangas, Steffen Leonhardt, Niku Oksala, Antti Vehkaoja

“…In the absence of motion, OHR technique is also able to estimate individual beat-to-beat intervals relatively well and can therefore also be used, for example, in monitoring of cardiac arrhythmias, stress, or sleep quality through heart rate variability (HRV) analysis. …”
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Validation of automatic measurement of QT interval variability. by Peter R Rijnbeek, Marten E van den Berg, Gerard van Herpen, Henk J Ritsema van Eck, Jan A Kors

“…Increased variability of beat-to-beat QT-interval durations on the electrocardiogram (ECG) has been associated with increased risk for fatal and non-fatal cardiac events. …”
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Slow breathing and hypoxic challenge: cardiorespiratory consequences and their central neural substrates. by Hugo D Critchley, Alessia Nicotra, Patrizia A Chiesa, Yoko Nagai, Marcus A Gray, Ludovico Minati, Luciano Bernardi

“…Activity in rostroventral medulla correlated with beat-to-beat blood pressure and heart rate variability. …”
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Pressure, Flow Rate and Operating Speed Characteristics of a Continuous Flow Left Ventricular Assist Device During Varying Speed Support by Selim Bozkurt

“…Therefore, understanding the relationship between speed, flow rate and the pressure difference across a pump may help to develop novel beat-to-beat operating modes to improve Continuous Flow Left Ventricular Assist Device support.…”
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A dynamical model for generating synthetic ballistocardiogram signals based on Extended Kalman Filter (EKF) by Zhang, Qifan

“…Then the time and phase information, like Beat-to-Beat, IJ and JK time intervals within a typical BCG waveform were calculated. …”
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Consistencies and differences in intermediate physiological phenotypes of vascular ageing between ischaemic stroke aetiologies by Webb, AJS, Wartolowska, KA, Li, L, Mazzucco, S, Rothwell, PM

“…<br><strong>Objective:<br></strong> Arterial stiffness, cerebral pulsatility, and beat-to-beat blood pressure variability partly mediate the relationship between hypertension and stroke, but it is unknown if these intermediate phenotypes of vascular ageing differ between stroke aetiologies. …”

Pressure‐based estimation of right ventricular ejection fraction by Paul M. Heerdt, Inderjit Singh, Ahmed Elassal, Vitaly Kheyfets, Manuel J. Richter, Khodr Tello

“…Adaptation of the pressure‐based estimation method to provide beat‐to‐beat RVEF also demonstrated significant correlation between the median beat‐to‐beat value over 10 s with cardiac MRI (r2 = 0.66; P < 0.001), and an area under the ROC curve of 0.94 ± 0.04 (CI = 0.86 to 1.00) with sensitivity and specificity of 78% and 86%, respectively, for predicting a maladaptive RV response. …”
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Spatiotemporal patterns of early afterdepolarizations underlying abnormal T-wave morphologies in a tissue model of the Purkinje-ventricular system. by Mengya Yuan, Heqiang Lian, Pan Li

“…We found that (1) while major inhibition of ICaL can substantially reduce the excitability of the PVS leading to conduction failures, moderate ICaL inhibition can promote occurrences of AP alternans at short cycle lengths (CLs), and EAD events preferentially occur with a major reduction of IKr (>50%) at long CLs; (2) with a minor reduction of ICaL, spatially synchronized steady-state EAD events with inverted and biphasic T-waves can be "weakened" into beat-to-beat concurrences of spatially synchronized EADs and T-wave alternans, and as pacing CLs increase, beat-to-beat concurrences of localized EADs with late-appearing and pointed T-wave morphologies can be observed; (3) under certain conditions, localized EAD events in the midmyocardium may trigger slow uni-directional electric propagation with inverted (antegrade) or upright (retrograde) broad-based T-waves; (4) spatially discordant EADs were typically characterized by desynchronized spontaneous onsets of EAD events between two groups of PVS tissues with biphasic T-wave morphologies, and they can evolve into spatially discordant oscillating EAD patterns with sustained or self-terminated alternating EAD and electrocardiogram (ECG) patterns. …”
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Implementation of Wavelet-Transform-Based Algorithms in an FPGA for Heart Rate and RT Interval Automatic Measurements in Real Time: Application in a Long-Term Ambulatory Electrocar... by José Alberto García Limón, Frank Martínez-Suárez, Carlos Alvarado-Serrano

“…The micro-SD memory stores the three leads and the RR and RT intervals, and an LCD screen displays the beat-to-beat values of heart rate, RT interval and the electrode connection. …”
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Significance of intra-operative blood pressure data resolution: A retrospective, observational study [version 1; referees: 2 approved] by Senthil Packiasabapathy, Ammu T. Susheela, Fernando Mujica, Balachundhar Subramaniam

“…Data was collected from two sources for each patient, one with beat-by-beat frequency, other at a frequency of once every 15 seconds. …”
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Heart Rate Variability and Long Chain <i>n</i>-3 Polyunsaturated Fatty Acids in Chronic Kidney Disease Patients on Haemodialysis: A Cross-Sectional Pilot Study by Ana M Pinto, Helen L MacLaughlin, Wendy L Hall

“…Higher ratios of erythrocyte eicosapentaenoic acid (EPA) to docosahexaenoic acid (DHA) were associated with lower 24 h vagally-mediated beat-to-beat HRV parameters. Higher plasma EPA and docosapentaenoic acid (DPA<i>n</i>-3) were also associated with lower sleep-time and 24 h beat-to-beat variability. …”
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Design and analysis of artifact-resistive finger photoplethysmographic sensors for vital sign monitoring by Rhee, Sokwoo

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Statistical analysis of heart beat time series by F. Atiyabi, M. Akbari Livari, K. Kaviani

“…We analyse the extended self-similarity (ESS) and recursive model in the beat-to-beat fluctuations in the heart rates of healthy subjects as well as those with congestive heart failure. …”
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T-wave alternans in long QT syndrome by Siddharth Narayan Gadage

“…T-wave alternans (TWA), a phenomenon of beat-to-beat variability in the repolarization phase of the ventricles, has been closely associated with an increased risk of ventricular tachyarrhythmic events (VTE) and sudden cardiac death (SCD).…”
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Measurement of Cardiac Mechanical Function in Isolated Ventricular Myocytes from Rats and Mice by Computerized Video-Based Imaging by Ren Jun, Wold Loren

“…The goal of this article is to describe the isolation of ventricular myocytes from both rats and mice, and the use of real-time beat-to-beat simultaneous recording of both myocyte contraction and intracellular Ca²⁺ transient.…”
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Diminution of Heart Rate Variability in Bipolar Depression by Brandon Hage, Briana Britton, David Daniels, Keri Heilman, Stephen W. Porges, Stephen W. Porges, Angelos Halaris

“…Autonomic nervous system (ANS) dysregulation in depression is associated with symptoms associated with the ANS. The beat-to-beat pattern of heart rate defined as heart rate variability (HRV) provides a noninvasive portal to ANS function and has been proposed to represent a means of quantifying resting vagal tone. …”
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Clinical Validation of Heart Rate Apps: Mixed-Methods Evaluation Study by Vandenberk, Thijs, Stans, Jelle, Mortelmans, Christophe, Van Haelst, Ruth, Van Schelvergem, Gertjan, Pelckmans, Caroline, Smeets, Christophe JP, Lanssens, Dorien, De Cannière, Hélène, Storms, Valerie, Thijs, Inge M, Vaes, Bert, Vandervoort, Pieter M

“…In the second study, a next step in validation was performed by comparing the beat-to-beat intervals of the FibriCheck app to a synchronized ECG recording. …”
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