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In this paper, a methodology to indirectly estimate the respiratory rate from the photoplethysmography (PPG) signal is presented. The possibility to reliably estimate respiratory rate from the PPG signal is particularly appealing since PPG is simple, comfortable and cheap. The underlying hypothesis of this methodology is that respiration provokes simultaneous changes in the pulse interval, amplitude...
Repolarization alternans (RA) is characterized by its amplitude and instant of occurrence along the JT segment, but only the amplitude is generally used to discriminate abnormal cases. The role of RA timing was focused in the present study. ECGs from 201 coronary-artery-disease (CAD) patients and 167 control-healthy (CH) subjects were analyzed by our heart-rate adaptive match filter (AMF) method to...
In this study, we used the bifurcation analysis technique to study the functional roles of the maximal channel conductace of the L-type calcium channel coded by isoforms of Cav1.2 and Cav1.3 in a novel mathematical model of murine sinoatrial node (SAN) cells. A continuous variation in the maximal channel conductance of ICaL (gCaL, 1.2 and gCaL, 1.3) was carried out to reveal the emergence and annihilation...
Diagnosis during cardiopulmonary resuscitation (CPR) is highly desirable because it has been reported to be determinant for a successful outcome from sudden cardiac arrest. This study evaluates the accuracy and the time-effect of applying CPR artefact suppression prior to rhythm classification with long out-of-hospital cardiac arrest episodes. A total of 191 episodes were considered corresponding...
Estimation of stroke volume and several other cardiovascular indices using impedance cardiography requires error-free detection of the characteristic points in the impedance cardiogram. A technique for automatic detection of B, C, and X points, using R peaks in the simultaneously acquired ECG as reference, is presented. It does not require estimation of the baseline and selection of processing parameters...
The level of motivation or stress influences learning the use of a robot-assist device for walking. Heart rate asymmetry (HRA) indicates the level of parasympathetic (HRA<0.5) and sympathetic (HRA>0.5) involvement in heart rate regulation. Three patients and seven controls were presented increasing levels of task difficulty. During training patients showed an increase in stress as indicated...
The layered structure of human heart is a challenging task for visualization. Conventional visualization method can hardly be used to provide satisfied rendering results due to the complex anatomical structure of human heart. In addition, it is very hard to find a balance between rendering the inner structure and the silhouettes of the heart. In this work we adopt the context-preserving volume rendering...
A reliable diagnosis by automated external defibrillators (AED) during cardiopulmonary resuscitation (CPR) would reduce hands-off time, thus increasing the resuscitation success. Several filters based on one (dual-channel) or multiple (multi-channel) reference signals have been proposed to remove the artifact induced on the ECG by chest compressions. However these filters were optimized and their...
Intracardiac organization indices such as atrial fibrillation (AF) cycle length (AFCL) have been used to track the efficiency of stepwise catheter ablation (step-CA) of long-standing persistent AF (pers-AF), however, with limited success. The timing between nearby bipolar intracardiac electrograms (EGMs) reflects the spatial dynamics of wavelets during AF. The extent of synchronization between EGMs...
Robust and automated classification and correction of ECG-derived heart beats are a necessary prerequisite for an accurate real-time estimation of measures of heart rate variability and cardiovascular control. In particular, the low quality of the signal, as well as the presence of recurring arrhythmic events, may significantly affect estimation accuracy. We here present a novel point process based...
Histogram and scatter plot are important graphical indices for heart rate variability (HRV) analysis. However, they are difficult to quantify the complexity for time series and have little specificity to some cardiovascular diseases. This paper proposed a new graphical method for HRV analysis, which was named as RR sequence normalized histogram. Based on the analysis of RR sequence normalized histogram,...
An algorithm to detect poor quality ECGs collected in low-resource environments is described (and was entered in the PhysioNet/Computing in Cardiology Challenge 2011 ‘Improving the quality of ECGs collected using mobile phones’). The algorithm is based on previously published signal quality metrics, with some novel additions, designed for intensive care monitoring. The algorithms have been adapted...
Finite element models (FEMs) have been already widely used to analyze mitral valve (MV) biomechanics. Recently, strategies to implement patient-specific, image-based FEMs of the MV were proposed, improving their realism. In particular, we proposed to implement MV FEMs from real time 3D transthoracic echocardiographic imaging. To allow a future clinical use of this approach as a support tool for MV...
The left ventricle (LV) has been widely studied and many segmentation methods have been proposed allowing accurate volume estimation from cardiac magnetic resonance imaging (CMRI). Anatomical complexity of the right ventricle (RV) has made accurate determination of RV shape and volume difficult. We propose a fully automated method for both RV and LV segmentation from CMRI. Datasets were analysed using...
Recent studies on heart rate variability (HRV) and QT interval variability (QTV) have shown that HRV and QTV might be related to some cardiac diseases. This study used higher order spectra (HOS) method and constructed a normalized bispectrum amplitude histogram, from which two quantitative indices: bispectrum amplitude entropy (BAEn) and high-low amplitude ratio (HLAr) were defined. A total of 49...
Quantification of the complexity of fibrillatory processes may objectify the modifications induced by a therapy. However, its evaluation is usually restricted to a subjective visual inspection. The objective of this work is to classify isochronal maps attending to their organization into 3 types. An automatic classification method based on spatio-temporal isolation of activation wavefronts is presented...
We study a model of the atrioventricular node function during atrial fibrillation (AF), for which the model parameters can be estimated from the ECG. The proposed model is defined by parameters which characterize the arrival rate of atrial impulses, the probability of an impulse choosing either one of the two atrioventricular nodal pathways, the refractory periods of these pathways, and the prolongation...
The main objective of this study is to investigate patterns of heart rate variability during concentration meditation to understand its effects on health. Our method consisted of three major stages: Signal acquisition, Feature extraction, and Classification. The input signals are RR interval signals which were collected from 105 subjects. By K-mean clustering method, the signals could be classified...
Abnormal intra-QRS potentials (AIQP) in signal-averaged electrocardiograms have been proposed to be a potential noninvasive index for the diagnosis of the risk of ventricular arrhythmias. This study tries to develop a nonlinear neural network using radial basis functions (RBF) to approximate the normal QRS complex and then to estimate the AIQP using the approximation error, and further to quantify...
Diagnostic electrocardiograms (ECG) are required to ensure patient safety during minimal invasive interventions and cardiac stress testings. The ECG is corrupted by several other signals when performing these interventions under magnetic resonance (MR) guidance which makes it impossible to use the ECG as a diagnostic tool in MR guided interventions. The interfering signal that is caused by the static...
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