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T-wave alternans (TWA) has been linked to increased vulnerability of the myocardium to ventricular fibrillation in different clinical conditions. Our aim in this work was to study and characterize TWA in an animal model of myocardial ischemia and infarction. Infarction was induced in 29 pigs by a 40-minute-long balloon inflation on the left anterior descending coronary artery. The occlusion recording,...
This study aimed to assess the accuracy of current ECG criteria for locating the coronary artery principally involved in an acute myocardial infarction (AMI) in order to evaluate the merits of implementing AHA/ACC recommendations that require the culprit artery be reported on an ECG interpretation. 12 lead ECGs were recorded in ambulances on patients with a suspected acute coronary syndrome. These...
We describe a data-driven approach, using a combination of machine learning algorithms to solve the 2011 Physionet/Computing in Cardiology (CinC) challenge — identifying data collection problems at 12 leads electrocardiography (ECG). Our data-driven approach reaches an internal (cross-validation) accuracy of almost 93% on the training set, and accuracy of 91.2% on the test set.
“Early repolarisation” has generally been considered benign until recently when it has been associated with life threatening arrhythmias. Because there has been confusion around defining J point elevation in relation to early repolarisation, this study examined ECGs recorded from an apparently healthy adult Caucasian cohort of males and females. As first step, the prevalence of end QRS notching, end...
An algorithm to determine quality of ECGs can enable inexperienced nurses and paramedics to record ECGs of sufficient diagnostic quality. We propose an algorithm that can assess the quality of an ECG designed for an Android-based platform. The algorithm is based on previously established ECG quality metrics for quantifying ECG quality but designed in a way to make it efficient to run on a mobile platform...
We estimate that as much as 5% of all recorded ECGs worldwide may, to some degree, suffer from poor signal quality or incorrect electrode positioning, which often interferes with correct interpretation of the ECG. Proper training of ECG technicians and regular inspection of signal quality is necessary to achieve a high standard. Due to the large amounts of ECGs recorded daily, we devised an automatic...
In this work, we present a semiautomatic algorithm for ECG heartbeat classification, based on a previously developed automatic classifier and a clustering algorithm. Both classifier and clustering algorithms include features from the RR interval series and morphology descriptors calculated from the wavelet transform. Integrating the decisions of both algorithms, the presented algorithm can work automatically...
We present an algorithm for assessing the ECG signal quality in real time. The algorithm is designed for small systems with low computational power. The method estimates the ECG cepstrum on a running window of 10 s and calculates the power of the highest peak in the “quefrency” band of the mean cardiac interval (between 0.25 and 2.0 s). If the ECG is corrupted by noise, the power of this cepstral...
Ejection fraction and microvolt T-wave alternans (mTWA) lack specificity to predict sudden cardiac death in heart failure (HF). We compared resting ECG variables (QRS duration, lead-dependent T-amplitudes) and exercise-ECG-derived TWA variables (amplitude in the 12 leads, in the orthogonal X, Y, Z leads and in the vector magnitude) of 56 HF patients with an implanted cardioverter-defibrillator: cases...
Work presented in this paper was undertaken in response to the PhysioNet/CinC Challenge 2011: Improving the quality of ECGs collected using mobile phones. For the purpose of this challenge we have developed an algorithm that uses five simple rules, detecting the most common distortions of the ECG signal in the out of hospital environment. Using five if-then rules arranges for easy implementation and...
The purpose to participate in the PhysioNet Challenge 2011 was to test our recent computational techniques that might help in assessing of the misplaced ECG electrodes. ECG recordings from the Challenge data sets were analyzed in three steps. First, general characteristics of the recorded signals were determined. Second, cluster analysis was applied to obtain templates that helped to estimate the...
Radiofrequency catheter ablation (CA) is increasingly employed to treat atrial fibrillation (AF), yet selection of patients who would actually benefit from this therapy still remains an open issue. The present work introduces some non-invasive quantitative parameters to discriminate between successful and failing CA procedures by exploiting the spatial diversity of the 12-lead surface ECG. They are...
State-of-the-art mobile ECG recorders are usually not intended to be used by untrained personnel or by patients themselves. For that purpose, a suitable graphical user interface that provides real-time feedback concerning the signal quality is required. We have developed a measure for mobile ECG quality assessment based on a) basic signal quality properties (amplitude, spikes, constant signal portions),...
This study was designed to investigate very-low-frequency modulation of QRS slopes in control electrocardiographic recordings of patients with stable angina pectoris admitted for prolonged elective percutaneous coronary intervention (PCI). This modulation occurs between 0.01Hz and 0.07Hz and has been described for QRS slopes as well as for heart rate variability (HRV). Results shows that power spectrum...
Biometric systems have for objective to perform identification, or identity verification, of individuals. Human ECG has been recently proposed as an additional tool for biometric applications. However, most of the existing studies are set in supine rest and only consider the QRS morphology after, most of the time, feature extraction from the ECG. This paper is focused on identification based on pattern...
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...
An ectopic heartbeat initiated by the ventricles is considered as Premature Ventricular Contraction (PVC) beat. For any individual, unifocal PVCs are typically monomorphic, whereas multifocal PVCs have polymorph contour. The ectopic rate especially of multimorphic PVCs is significantly associated with sudden death and many other main arrhythmic events. In order to group PVCs upon their morphology,...
A computationally efficient electrocardiogram (ECG) quality classifier is developed. It is based on the residuals between filtered and observed data, and between the best subset linear predictions without the constant term and the filtered data. Amplitude information is also used. First, the ECG is filtered for essential spectrum bandpass and interference removal. Then, the prediction of each lead...
For the application of acquiring ECGs from mobile telephones by unskilled users it would be beneficial if the mobile device could assess ECG quality and inform the user if the quality was acceptable. Using the PhysioNet/Computing in Cardiology Challenge 2011 dataset we identified several ECG features that were commonly observed in the training set ‘unacceptable’ category for algorithmic development:...
The genesis of the U wave in the ECG is still in doubt. This study aimed to investigate the relationship between the occurrence of the U wave and both the electrical and mechanical timing sequence in heart beats. The M-mode echocardiography and 12-lead ECG were simultaneously recorded from 4 healthy subjects, with four repeat measurements in each. The ECG for both aortic valve (AV) and mitral valve...
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