1,720,982 research outputs found
Development of PDF-ECG : Further steps towards the long-term preservation of clinical electrocardiograms
No full textHeartScope : a software tool addressing autonomic nervous system regulation
No full textThe evaluation of cardiovascular control system requires ad-hoc software tools specifically designed to address the complexity of the regulation mechanisms in a multiparametric and multidisciplinary perspective. We introduce HeartScope a Windows-based C++ tool that brings together the most advanced signal processing methods for the analysis of cardiovascular regulation in a flexible and friendly framework
Proof of concept for an international long-time preservation ECG format
Full text linkWe present a proof-of-concept of a medical data format for storing and retrieving 12-lead, 10-second standard electrocardiograms (ECG). The new format combines a digital ECG record into a standard graphical report (PDF). Using the very recent PDFIA-3 standard (ISO 19005-3:2012), we designed a long-term preservation graphic report (such as a standard 3 ×4 or 6×2 ECG printout) in which the original ECG digital data (using the aECG ANSIIHL7 R1-2004 format) is embedded as a compressed attachment. The proposal also includes two wcrys of ensuring conformity between the ECG vector images and the digital data. First, a digital signature is added to guarantee that the document was not modified after creation. Second, specific metadata are inserted to allow a direct digital comparison between the vector ECG printout and the data. To prove the feasibility of the approach, 93 aECGs, selected from different device manufacturers, resolutions and sample rates, were converted into the new format and then validated. Differences between digital data and vector graphics were alwcrys smaller than 0.02 μV, significantly below the typical AID converter resolution
Quantification of ventricular repolarization heterogeneity during sotalol administration using the V-index
No full textAssessing autonomic response to repeated bouts of exercise below and above respiratory threshold : insight from dynamic analysis of RR variability
No full textPurpose: The dynamics of vagal withdrawal and reactivation during pulses of exercise are described by indices computed from heart period (RR) variations, which may be sensitive to duration and load. We sought to assess the consistency over time of these indices, which is not well established. Methods: We recorded continuous electrocardiogram during series of five successive bouts (2 min) of submaximal exercise (at 40 and 70 % of VO2peak, different days). Autonomic responsiveness was inferred from quantification of onset and offset of RR dynamics of each individual bout. Consistency of results was assessed with intraclass correlation (ICC). Results: During exercise bouts, indices from tachycardic and bradycardic transients reach lower levels in response to higher exercise loads and progression of exercise. There is a significant effect of load and time (i.e., bout repetition) for all examined variables, with a clear interaction. However, no interaction is observed with the 60 s change in heart rate. ICC analysis demonstrates that various indices are characterized by large differences in stability, which is generally greater within the same day (e.g., tachyspeed ICC at 40 % = 0.751, at 70 % = 0.704, both days = 0.633; bradyspeed, respectively, = 0.545, 0.666, 0.516). Conclusions: Intensity and duration of exercise modulate vagal withdrawal and reactivation. Analysis of RR variations, during successive brief exercise bouts at lower and higher intensity, ensures a consistency similar to that reported for autonomic cardiac regulation at rest and might guide the choice among multiple indices that are obtained from the tachogram. © 2014 Springer-Verlag Berlin Heidelberg
A fully automatic algorithm for the analysis of heart rate changes and cardiac recovery during exercise
No full textExercise test is a challenging experimental condition for signal processing tools since stationarity requirement is not fulfilled. The aim of the present study was to develop a new way to look at HR and RR variability in exercise test, focusing both on exercise and the subsequent recovery phase. From RR series, the first derivative of the filtered tachogram and the variance were calculated in windows of predefined length and the three experimental conditions (rest, exercise and recovery) were automatically detected. Results indicate that in healthy subjects variance is larger during recovery than during exercise for a given RR interval, this is not seen in heart failure patients. In healthy subjects tonic and dynamical control of heart rate should be regarded as different autonomic regulations
Dynascope: a software tool for the analysis of heart rate variability during exercise
Full text linkHeart Rate Variability is usually studied using spectral analysis in stationary conditions, but this kind of study cannot be applied during exercise tests where stationarity decays. To study dynamic situations a software tool has been designed to evaluate HR changes during non stationary conditions. We introduce DynaScope a Windows-based C++ software containing algorithms developed to analyse RR variability where spectral analysis cannot be applied
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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