ОЦЕНКА СТАТИСТИЧЕСКИХ ХАРАКТЕРИСТИК МИОГРАФИЧЕСКОЙ ПОМЕХИ ПРИ МНОГОКАНАЛЬНОЙ РЕГИСТРАЦИИ ЭЛЕКТРОКАРДИОСИГНАЛА

Electromyographic noise is one of the most common noises in electrocardiogram. In case of several electrocardiogram leads, electromyographic noise affects each lead to different extent. It can be taken into account when developing algorithms for multilead electrocardiogram record processing. However, in the existing literature, there is no information about the relationship of electromyographic noise in various ECG leads and their joint probability distribution. The purpose of this paper is to study statistical characteristics of electromyographic noise in ECG signal, from which the electromyographic noise is extracted. The paper proposes a method for extracting electromyographic noise from electrocardiogram signal, based on a polynomial approximation of electrocardiogram signal fragments in sliding window with overlapping fragment subsequent weight averaging. Using this method, fragments of electromyographic noise are extracted from multichannel electrocardiogram records. Based on the obtained data, a joint probability distribution function of electromyographic noise in two adjacent leads is selected, and the correlation relationships between the electromyographic noise in various ECG leads are investigated. The results show that the joint probability distribution function of electromyographic noise in two adjacent leads in the first approximation can be described using bivariate normal distribution. In addition, between the samples of electromyographic noise from two adjacent leads quite strong correlation relationships can be observed.Миографическая помеха является одной из самых распространенных помех, присутствующих в электрокардиосигнале. В случае использования нескольких отведений электрокардиосигнала миографическая помеха в разной степени оказывает влияние на каждое из отведений. Это влияние может быть учтено при построении алгоритмов обработки многоканальных записей электрокардиосигнала. Однако в существующей литературе недостаточно полно исследован анализ взаимосвязей отсчетов миографической помехи в различных отведениях электрокардиосигнала. Цель работы – эмпирическое исследование статистических характеристик миографической помехи, выделенной из зашумленных фрагментов электрокардиосигнала. Предложен метод выделения миографической помехи из записей электрокардиосигнала. Метод основан на полиномиальной аппроксимации фрагментов электрокардиосигнала в скользящем окне с последующим весовым усреднением перекрывающихся фрагментов. С использованием данного метода из многоканальных записей электрокардиосигнала были выделены фрагменты миографической помехи. На основе выделенных фрагментов подобрано совместное распределение отсчетов миографической помехи в двух смежных отведениях, а также исследованы корреляционные взаимосвязи между отсчетами миографической помехи в различных отведениях электрокардиосигнала. В результате установлено, что совместное распределение отсчетов миографической помехи в двух смежных отведениях в первом приближении может быть описано с помощью двумерного нормального закона. Кроме того, между отсчетами миографической помехи из двух смежных отведений могут наблюдаться довольно сильные корреляционные взаимосвязи

EVALUATION OF ELECTROMYOGRAPHIC NOISE STATISTICAL CHARACTERISTICS IN MULTICHANNEL ECG RECORDINGS

Electromyographic noise is one of the most common noises in electrocardiogram. In case of several electrocardiogram leads, electromyographic noise affects each lead to different extent. It can be taken into account when developing algorithms for multilead electrocardiogram record processing. However, in the existing literature, there is no information about the relationship of electromyographic noise in various ECG leads and their joint probability distribution. The purpose of this paper is to study statistical characteristics of electromyographic noise in ECG signal, from which the electromyographic noise is extracted. The paper proposes a method for extracting electromyographic noise from electrocardiogram signal, based on a polynomial approximation of electrocardiogram signal fragments in sliding window with overlapping fragment subsequent weight averaging. Using this method, fragments of electromyographic noise are extracted from multichannel electrocardiogram records. Based on the obtained data, a joint probability distribution function of electromyographic noise in two adjacent leads is selected, and the correlation relationships between the electromyographic noise in various ECG leads are investigated. The results show that the joint probability distribution function of electromyographic noise in two adjacent leads in the first approximation can be described using bivariate normal distribution. In addition, between the samples of electromyographic noise from two adjacent leads quite strong correlation relationships can be observed

The effects of the cardiac myosin activator, omecamtiv mecarbil, on cardiac function in systolic heart failure:a double-blind, placebo-controlled, crossover, dose-ranging phase 2 trial

Background: Many patients with heart failure remain symptomatic and have a poor prognosis despite existing treatments. Decreases in myocardial contractility and shortening of ventricular systole are characteristic of systolic heart failure and might be improved by a new therapeutic class, cardiac myosin activators. We report the first study of the cardiac myosin activator, omecamtiv mecarbil, in patients with systolic heart failure. Methods: We undertook a double-blind, placebo-controlled, crossover, dose-ranging, phase 2 trial investigating the effects of omecamtiv mecarbil (formerly CK-1827452), given intravenously for 2, 24, or 72 h to patients with stable heart failure and left ventricular systolic dysfunction receiving guideline-indicated treatment. Clinical assessment (including vital signs, echocardiograms, and electrocardiographs) and testing of plasma drug concentrations took place during and after completion of each infusion. The primary aim was to assess safety and tolerability of omecamtiv mecarbil. This study is registered at ClinicalTrials.gov, NCT00624442. Findings: 45 patients received 151 infusions of active drug or placebo. Placebo-corrected, concentration-dependent increases in left ventricular ejection time (up to an 80 ms increase from baseline) and stroke volume (up to 9·7 mL) were recorded, associated with a small reduction in heart rate (up to 2·7 beats per min; p<0·0001 for all three measures). Higher plasma concentrations were also associated with reductions in end-systolic (decrease of 15 mL at >500 ng/mL, p=0·0026) and end-diastolic volumes (16 mL, p=0·0096) that might have been more pronounced with increased duration of infusion. Cardiac ischaemia emerged at high plasma concentrations (two patients, plasma concentrations roughly 1750 ng/mL and 1350 ng/mL). For patients tolerant of all study drug infusions, no consistent pattern of adverse events with either dose or duration emerged. Interpretation: Omecamtiv mecarbil improved cardiac function in patients with heart failure caused by left ventricular dysfunction and could be the first in class of a new therapeutic agent