Jimena Grandez Paredes - Academia.edu (original) (raw)

Uploads

Papers by Jimena Grandez Paredes

2020 Computing in Cardiology Conference (CinC)

Machine learning (ML) techniques can perform as better as humans at key healthcare tasks. Recent ... more Machine learning (ML) techniques can perform as better as humans at key healthcare tasks. Recent advances make it possible to perform, using ML, automatic high-level feature extraction and classification of cardiac arrhythmia. In this work, we aimed through a systematic literature review to identify the principal methods, databases, and contributions of ML on cardiac arrhythmias classification. Electronic database including PubMed, Science Direct, IEEE, Scielo, Scopus, and Web of Science were searched, from 2014 to 2019, by combining the following keywords "ECG", "heart signals", "arrhythmia", "classification" and "machine learning". 28 studies were selected as eligible. Classifications classes ranged from 2 to 17, with prevalence of 2 classes (71.4% of the studies). The most frequent applied methods were Artificial Neural Network (13 articles), followed by Support Vector Machines and Mixed techniques (5 articles respectively). MIT-BIH Arrhythmia Database was used in 15 studies (54%), whereas 8 (28.5%) utilized their own data. The approach basis for evaluating the results is the confusion matrix, where up to 82% of the studies used accuracy, 67.8% precision, and 46% sensitivity/specificity. Classification of cardiac arrhythmias through ECG is of increasing interest from the research groups, and ML classification is showing rising levels of performance. It would benefit both patients and clinicians.

Frontiers in Physiology

Conduction velocity (CV) slowing is associated with atrial fibrillation (AF) and reentrant ventri... more Conduction velocity (CV) slowing is associated with atrial fibrillation (AF) and reentrant ventricular tachycardia (VT). Clinical electroanatomical mapping systems used to localize AF or VT sources as ablation targets remain limited by the number of measuring electrodes and signal processing methods to generate high-density local activation time (LAT) and CV maps of heterogeneous atrial or trabeculated ventricular endocardium. The morphology and amplitude of bipolar electrograms depend on the direction of propagating electrical wavefront, making identification of low-amplitude signal sources commonly associated with fibrotic area difficulty. In comparison, unipolar electrograms are not sensitive to wavefront direction, but measurements are susceptible to distal activity. This study proposes a method for local CV calculation from optical mapping measurements, termed the circle method (CM). The local CV is obtained as a weighted sum of CV values calculated along different chords spann...

Facultad de Medicina, May 18, 2021

2019 Computing in Cardiology Conference (CinC), 2019

Body surface potential mapping (BSPM) systems allow non-invasive investigation of the spatial-tem... more Body surface potential mapping (BSPM) systems allow non-invasive investigation of the spatial-temporal behaviour of cardiac electrical activity. This study aims to present the validation (application) of 62-channel BSPM equipment. 12-lead ECG plus two leads on the back were recorded (21 healthy volunteers) and further segmented for 4 consecutive beats allowing to obtain P, QRS and T peaks and heart activity R-R, PR, QRS, ST and QT segments. The vectorcardiograms (VCG) are extracted from the electrodes placed on the torso (direct measurement-DM) or indirectly by the Inverse Dower, Uijen and Willems methods. 17 instants of time during one heart beat (P-QRS-T) (Figure 2) are used to generate sequential isopotential maps for each healthy volunteer to investigate propagation of highest and lowest potentials presented on each map. The results obtained in healthy volunteers are comparable with results in the literature, suggesting the system can help identifying heart rhythm disorders, in patients.

Frontiers in Physiology, 2021

Electrocardiographic imaging (ECGI) is a technique to reconstruct non-invasively the electrical a... more Electrocardiographic imaging (ECGI) is a technique to reconstruct non-invasively the electrical activity on the heart surface from body-surface potential recordings and geometric information of the torso and the heart. ECGI has shown scientific and clinical value when used to characterize and treat both atrial and ventricular arrhythmias. Regarding atrial fibrillation (AF), the characterization of the electrical propagation and the underlying substrate favoring AF is inherently more challenging than for ventricular arrhythmias, due to the progressive and heterogeneous nature of the disease and its manifestation, the small volume and wall thickness of the atria, and the relatively large role of microstructural abnormalities in AF. At the same time, ECGI has the advantage over other mapping technologies of allowing a global characterization of atrial electrical activity at every atrial beat and non-invasively. However, since ECGI is time-consuming and costly and the use of electrical ...

Heart Rhythm O2, 2021

Background In March 2020, hydroxychloroquine (HCQ) alone or combined with azithromycin (AZM) was ... more Background In March 2020, hydroxychloroquine (HCQ) alone or combined with azithromycin (AZM) was authorized as a treatment for COVID-19 in many countries. The therapy proved ineffective with long QT and deadly cardiac arrhythmia risks, illustrating challenges to determine the new safety profile of repurposed drugs. Objective To investigate proarrhythmic effects and mechanism of HCQ and AZM (combined and alone) with high doses of HCQ as in the COVID-19 clinical trials. Methods Proarrhythmic effects of HCQ and AZM are quantified using optical mapping with voltage-sensitive dyes in ex vivo Langendorff-perfused guinea pig (GP) hearts and with numerical simulations of a GP Luo-Rudy and a human O’Hara-Virag-Varro-Rudy models, for Epi, Endo, and M cells, in cell and tissue, incorporating the drug’s effect on cell membrane ionic currents. Results Experimentally, HCQ alone and combined with AZM leads to long QT intervals by prolonging the action potential duration and increased spatial dispersion of action potential (AP) repolarization across the heart, leading to proarrhythmic discordant alternans. AZM alone had a lesser arrhythmic effect with less triangulation of the AP shape. Mathematical cardiac models fail to reproduce most of the arrhythmic effects observed experimentally. Conclusions During public health crises, the risks and benefits of new and repurposed drugs could be better assessed with alternative experimental and computational approaches to identify proarrhythmic mechanisms. Optical mapping is an effective framework suitable to investigate the drug’s adverse effects on cardiac cell membrane ionic channels at the cellular level and arrhythmia mechanisms at the tissue and whole-organ level.