Search results for "Rhythm"
showing 10 items of 822 documents
Quantification of synchronization during atrial fibrillation by Shannon entropy: Validation in patients and computer model of atrial arrhythmias
2005
Atrial fibrillation (AF), a cardiac arrhythmia classically described as completely desynchronized, is now known to show a certain amount of synchronized electrical activity. In the present work a new method for quantifying the level of synchronization of the electrical activity recorded in pairs of atrial sites during atrial fibrillation is presented. A synchronization index (Sy) was defined by quantifying the degree of complexity of the distribution of the time delays between sites by Shannon entropy estimation. The capability of Sy to discriminate different AF types in patients was assessed on a database of 60 pairs of endocardial recordings from a multipolar basket catheter. The analysis…
Fiat lux: the light became therapy. An overview on the Bright Light Therapy in Alzheimer’s Disease sleep disorders
2020
Background: A system of photosensitive retinal ganglion cells provides ‘non-visual’ information on the circadian sequences of light to the suprachiasmatic nucleus (SCN), which, as the ‘master clock’, synchronizes the chronobiological mechanisms of all the biological clocks. Damage to SCN structure alters circadian behavioral and hormonal rhythms and interferes with a regular sleep-wake pattern. Several studies have shown that, in aging and in Alzheimer’s disease (AD), circadian rhythms change their synchronization with the environment and behavior loses sync with light. Objective: The current overview aims to examine research studies showing the effect of bright light therapy (BLT) on sleep…
Apnea detection using cardiac rhythm and its hardware implementation
2009
Abstract Sleep apnea is a sleep disorder characterized by pauses in breathing during sleep. Its detection is very important to avoid important disorders in the patients such as daytime fatigue and sleepiness, which might be very dangerous in certain work places. One of the methods to detect apnea is based in the cardiac rhythm, measuring some parameters which indicate the presence of respiration abnormalities. This work describes the used algorithm to detect apnea and its hardware implementation in an FPGA device for real time detection using the electrocardiogram (ECG) signal.
What links BRAF to the heart function? new insights from the cardiotoxicity of BRAF inhibitors in cancer treatment
2015
The RAS-related signalling cascade has a fundamental role in cell. It activates differentiation and survival. It is particularly important one of its molecules, B-RAF. B-RAF has been a central point for research, especially in melanoma. Indeed, it lacked effective therapeutic weapons since the early years of its study. Molecules targeting B-RAF have been developed. Nowadays, two classes of molecules are approved by FDA. Multi-target molecules, such as Sorafenib and Regorafenib, and selective molecules, such as Vemurafenib and Dabrafenib. Many other molecules are still under investigation. Most of them are studied in phase 1 trials. Clinical studies correlate B-RAF inhibitors and QT prolonga…
Coupling of Action-Perception Brain Networks during Musical Pulse Processing: Evidence from Region-of-Interest-Based Independent Component Analysis
2017
Our sense of rhythm relies on orchestrated activity of several cerebral and cerebellar structures. Although functional connectivity studies have advanced our understanding of rhythm perception, this phenomenon has not been sufficiently studied as a function of musical training and beyond the General Linear Model (GLM) approach. Here, we studied pulse clarity processing during naturalistic music listening using a data-driven approach (independent component analysis; ICA). Participants’ (18 musicians and 18 controls) functional magnetic resonance imaging (fMRI) responses were acquired while listening to music. A targeted region of interest (ROI) related to pulse clarity processing was defined…
Prosodic phenomena in simultaneous interpreting
2005
This paper reports on an empirical study on prosody in English-German simultaneous interpreting. It discusses prosody with particular reference to its tonal, durational and dynamic features, such as intonation, pauses, rhythm and accent, as well as its main functions, i.e. structure and prominence. Following a review of previous studies on the topic, a conceptual approach for the analysis of prosody in terms of structure and prominence is developed and subsequently applied to an authentic corpus of professional simultaneous interpretation consisting of three German versions of a 72-minute English source text. Prosodic patterns in the corpus are analyzed by means of a computer-aided method u…
Analysis of electrolyte abnormalities and the mechanisms leading to arrhythmias in heart failure. A literature review.
2016
About 50% of deaths from heart failure (HF) are sudden, presumably referable to arrhythmias. Electrolyte and acid-base abnormalities are a frequent and potentially dangerous complication in HF patients. Their incidence is almost always correlated with the severity of cardiac dysfunction; furthermore leading to arrhythmias, these imbalances are associated with a poor prognosis. The frequency of ventricular ectopic beats and sudden cardiac death correlate with both plasma and whole body levels of potassium, especially in alkalemia. The early recognition of these alterations and the knowledge of the pathophysiological mechanisms are useful for the management of these HF patients.
Two light sensors decode moonlight versus sunlight to adjust a plastic circadian/circalunidian clock to moon phase
2021
AbstractMany species synchronize their physiology and behavior to specific hours. It is commonly assumed that sunlight acts as the main entrainment signal for ~24h clocks. However, the moon provides similarly regular time information, and increasingly studies report correlations between diel behavior and lunidian cycles. Yet, mechanistic insight into the possible influences of the moon on ~24hr timers is scarce.We studiedPlatynereis dumeriliiand uncover that the moon, besides its role in monthly timing, also schedules the exact hour of nocturnal swarming onset to the nights’ darkest times. Moonlight adjusts a plastic clock, exhibiting <24h (moonlit) or >24h (no moon) periodicity. Abun…
Mechanism of Sinoatrial Node Dysfunction in a RyR 2 R420Q Mouse Model Ofcatecholaminergic Polymorphic Ventricular Tachycardia
2017
Catecholaminergic polymorphic ventricular tachycardia (CPVT) is a genetic disease characterized by stress-induced syncope and/or sudden death in young individuals with structurally normal heart. More than 150 mutations located in the cardiac Ca2+ release channel (type-2 ryanodine receptor, RyR2) gene are related to CPVT. Besides ventricular tachycardia (VT) under stress, sinoatrial node (SAN) dysfunction is frequently observed in CPVT patients. However, the cellular mechanisms remain underexplored. We created a KI mice model bearing a mutation in the N-terminal portion of the RyR2 found in a CPVT family, RyR2(R420Q). ECGs were recorded in KI and WT littermates in resting condition and after…
Cirugía de las arritmias en las cardiopatías congénitas
2008
La propia fisiopatología de las cardiopatías congénitas y el impacto de algunas correcciones quirúrgicas pueden predisponer al desarrollo de arritmias cardíacas, que incluyen taquicardia supraventricular macrorreentrante, flutter, fibrilación auricular, taquicardia auricular ectópica, taquicardia ventricular, síndrome del seno enfermo, bloqueo auriculoventricular y muerte súbita, entre otras. En la actualidad el tratamiento definitivo de estas arritmias y su profilaxis durante la corrección quirúrgica son procesos eficaces, con baja morbilidad y gran beneficio clínico para el paciente. En este trabajo se revisa el estado actual del tratamiento quirúrgico de las arritmias en las cardiopatías…