Juan Pablo Martínez

Juan Pablo Martínez
University of Zaragoza | UNIZAR · Engineering Research Institute of Aragon

Ph.D.

About

207
Publications
25,796
Reads
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4,423
Citations
Citations since 2017
68 Research Items
2259 Citations
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20172018201920202021202220230100200300400
20172018201920202021202220230100200300400
20172018201920202021202220230100200300400
Additional affiliations
December 1999 - present
University of Zaragoza
Position
  • Profesor Titular de Universidad / Associate Professor

Publications

Publications (207)
Article
Full-text available
Atrial fibrosis plays a key role in the initiation and progression of atrial fibrillation (AF). Atrial fibrosis is typically identified by a peak-to-peak amplitude of bipolar electrograms (b-EGMs) lower than 0.5 mV, which may be considered as ablation targets. Nevertheless, this approach disregards signal spatiotemporal information and b-EGM sensit...
Article
Full-text available
Objective: T-wave alternans (TWA) manifests as beat-to-beat fluctuations of T-wave morphology on the electrocardiogram (ECG), with physiological bases not fully understood. Using a biophysical model of the ECG, we demonstrate and give explicit relations that TWA depends on the i) spatial covariance between myocytes' repolarization time and alterna...
Article
Atrial fibrillation (AF) is the most frequent arrhythmia in clinical practice. It usually initiates as a paroxysmal activity (PxAF), with the subject having sinus rhythm, with interleaved AF episodes. The objective of the study is to evaluate the observations made by Pyotr Platonov, who hypothesized that slower conduction in the atria and the prese...
Article
Background: T-wave (TW) morphology indices based on time-warping ( dw) have shown significant cardiovascular risk stratification value. However, errors in the location of TW boundaries may impact their prognostic power. Our aim was to test the hypothesis that a weighted time-warping function (WF) would reduce the sensitivity of dw to these errors...
Article
Full-text available
We aim to provide a critical appraisal of basic concepts underlying signal recording and processing technologies applied for (i) atrial fibrillation (AF) mapping to unravel AF mechanisms and/or identifying target sites for AF therapy and (ii) AF detection, to optimize usage of technologies, stimulate research aimed at closing knowledge gaps, and de...
Conference Paper
Full-text available
Resumen La morfología de la onda T (TW) se ha investigado para desarrollar marcadores de predicción de riesgo arrítmico específicos como , que cuantifica el nivel de "warping" necesario para alinear temporalmente una TW con respecto a otra de referencia a diferente ritmo cardiaco. Sin embargo, los errores de delineación de los límites de la TW pued...
Article
Se pretende mejorar la detección del final de la onda T (Te) de la señal de electrocardiograma (ECG) grabada durante prueba de esfuerzo. Así, los puntos Te se calculan en la primera derivación transformada de los métodos PCA y piCA, y se comparan con losextraídos directamente del ECG.
Article
La fibrosis auricular representa un papel clave en la patogenia de la fibrilación auricular, y es un factor importante para el guiado de procedimientos de ablación con catéter. Se consideran fibróticas las áreas cuyos electrogramas bipolares (b-EGMs) presentan una amplitud pico-a-pico inferior a 0.5 mV [1]. Sin embargo, la amplitud de dichas señale...
Article
Full-text available
The two most common modes of death among chronic heart failure (CHF) patients are sudden cardiac death (SCD) and pump failure death (PFD). Periodic repolarization dynamics (PRD) quantifies low-frequency oscillations in the T wave vector of the electrocardiogram (ECG) and has been postulated to reflect sympathetic modulation of ventricular repolariz...
Article
Full-text available
Introduction: The omnipolar electrogram method was recently proposed to try to generate orientation-independent electrograms. It estimates the electric field from the bipolar electrograms of a clique, under the assumption of locally plane and homogeneous propagation. The local electric field evolution over time describes a loop trajectory from whic...
Article
Full-text available
Objective The aim of this study is to compare the performance of two electrocardiogram (ECG) lead-space reduction (LSR) techniques in generating a transformed ECG lead from which T-wave morphology markers can be reliably derived to non-invasively monitor blood potassium concentration ([K+]) in end-stage renal disease (ESRD) patients undergoing hemo...
Article
Full-text available
Background: End-stage renal disease patients undergoing hemodialysis (ESRD-HD) therapy are highly susceptible to malignant ventricular arrhythmias caused by undetected potassium concentration ([K+]) variations (Δ[K+]) out of normal ranges. Therefore, a reliable method for continuous, noninvasive monitoring of [K+] is crucial. The morphology of the...
Article
Full-text available
Background Atrial fibrillation (AF) is the most common supraventricular arrhythmia characterized by disorganized atrial electrical activity, maintained by localized arrhythmogenic atrial drivers. Pulmonary vein isolation (PVI) allows to exclude PV-related drivers. However, PVI is less effective in patients with additional extra-PV arrhythmogenic dr...
Article
Full-text available
We investigated the ability of time-warping-based ECG-derived markers of T-wave morphology changes in time (dw) and amplitude (da), as well as their non-linear components (dwNL and daNL), and the heart rate corrected counterpart (dw,c), to monitor potassium concentration ([K+]) changes (Δ[K+]) in end-stage renal disease (ESRD) patients undergoing h...
Preprint
Full-text available
Background: End-stage renal disease (ESRD) patients undergoing hemodyalisis therapy (HD) experience blood potassium ([K + ]) variations that are reflected on the T-wave (TW) morphology. Methods: We evaluated the performance of different lead space reduction (LSR) methods: principal component analysis (PCA), maximising the TW energy, and two derived...
Article
Este trabajo evalúa la capacidad del índice Periodic Repolarization Dynamics (PRD) para predecir el riesgo de sufrir muerte súbita cardíaca (MSC) o muerte por fallo de bomba (MFB) en pacientes con insuficiencia cardíaca crónica (ICC).
Article
En este trabajo se proponen marcadores no invasivos para estratificar pacientes según su riesgo de sufrir arritmias ventriculares que pueden desencadenar en muerte súbita cardiaca. Estos marcadores se basan en la respuesta del intervalo QT del ECG durante la prueba de esfuerzo, donde los cambios del ritmo cardiaco tienen un rango mayor de variación...
Conference Paper
Full-text available
Atrial fibrillation (AF) is the most frequent irregular heart rhythm due to disorganized atrial electrical activity, often sustained by rotational drivers called rotors. The non-invasive localization of AF drivers can lead to improved personalized ablation strategy, suggesting pulmonary vein (PV) isolation or more complex extra-PV ablation procedur...
Conference Paper
Full-text available
Atrial fibrillation (AF) is an irregular heart rhythm due to disorganized atrial electrical activity, often sustained by rotational drivers called rotors. In the present work, we sought to characterize and discriminate whether simulated single stable rotors are located in the pulmonary veins (PVs) or not, only by using non-invasive signals (i.e., t...
Article
Full-text available
Background: Voltage mapping allows identifying the arrhythmogenic substrate during scar-related ventricular arrhythmia (VA) ablation procedures. Slow conducting channels (SCCs), defined by the presence of electrogram (EGM) signals with delayed components (EGM-DC), are responsible for sustaining VAs and constitute potential ablation targets. Howeve...
Article
Full-text available
Ventricular arrhythmias and sudden cardiac death during long-term space missions are a major concern for space agencies. Long-duration spaceflight and its ground-based analog head-down bed rest (HDBR) have been reported to markedly alter autonomic and cardiac functioning, particularly affecting ventricular repolarization of the electrocardiogram (E...
Article
Full-text available
Objective: To develop and evaluate an algorithm for the selection of the best performing QRS detections from multiple algorithms and ECG leads. Approach: The detections produced by several publicly available single-lead QRS detectors are segmented in 20 seconds consecutive windows. Then a statistical model is trained to estimate a quality metric...
Article
Objective: To assess the effects of different durations of simulated microgravity exposure on ventricular repolarization (VR) in terms of T-wave alternans (TWA) as well as to test whether an increase in VR heterogeneity could be detected once normal gravity was restored. Approach: A total of 63 healthy volunteers were recruited in several head-d...
Article
Full-text available
Patients with left bundle branch block (LBBB) are known to have a good clinical response to cardiac resynchronization therapy. However, the high number of false positive diagnosis obtained with the conventional LBBB criteria limits the effectiveness of this therapy, which has yielded to the definition of new stricter criteria. They require prolonge...
Conference Paper
Full-text available
Chronic heart failure (CHF) represents one of the major public health problems that often end in sudden cardiac death (SCD). Atrial fibrillation (AF) is associated with an increased risk of SCD but nowadays there is no non-invasive method that accurately predicts that risk. The recently developed T-wave morphology restitution (TMR) index showed its...
Article
Objective: Atrial fibrillation (AF) rhythm gives rise to an irregular response in ventricular activity, preventing the use of standard ECG-derived risk markers based on ventricular repolarization heterogeneity under this particular condition. In this study we proposed new indices to quantify repolarization variations in AF patients, assessing thei...
Article
Widely developed for clinical screening, electrocardiogram (ECG) recordings capture the cardiac electrical activity from the body surface. ECG analysis can therefore be a crucial first step to help diagnose, understand and predict cardiovascular disorders responsible for 30% of deaths worldwide. Computational techniques, and more specifically machi...
Article
Monitoring of ventricular premature beats (VPBs), being abundant in hemodialysis patients, can provide information on cardiovascular instability and electrolyte imbalance. In this paper, we describe a method for VPB detection which explores the signals acquired from the arterial and the venous pressure sensors, located in the extracorporeal blood c...
Book
Full-text available
The aim of the Regional dossiers series is to provide a concise description of European minority languages in education. Aspects that are addressed include features of the education system, recent educational policies, main actors, legal arrangements and support structures, as well as quantitative aspects such as the number of schools, teachers, pu...
Article
Full-text available
Background Sudden cardiac death (SCD) and pump failure death (PFD) are common endpoints in chronic heart failure (CHF) patients, but prevention strategies are different. Currently used tools to specifically predict these endpoints are limited. We developed risk models to specifically assess SCD and PFD risk in CHF by combining ECG markers and clini...
Data
Construction of the models. (DOCX)
Data
Univariable predictors of SCD in both reduced and preserved LVEF populations. (DOCX)
Data
Multivariable predictors of SCD in both reduced and preserved LVEF populations. (DOCX)
Data
Clinical and ECG data. (XLSX)
Data
Definition of the dichotomized variables used to build SCD and PFD risk models. (DOCX)
Data
Univariable predictors of PFD in both reduced and preserved LVEF populations. (DOCX)
Data
Multivariable predictors of PFD in both reduced and preserved LVEF populations. (DOCX)
Article
Purpose Activation mapping is used to guide ablation of idiopathic outflow tract ventricular arrhythmias (OTVAs). Isochronal activation maps help to predict the site of origin (SOO): left vs right outflow tract (OT). We evaluate an algorithm for automatic activation mapping based on the onset of the bipolar electrogram (EGM) signal for predicting t...
Conference Paper
Full-text available
Background: Voltage mapping is useful in identifying the arrhythmogenic substrate in post-myocardial infarction (MI) ventricular arrhythmias (VAs). Slow conducting channels (CCs) are small bundles of viable myocardium embedded within the scar that allow reentry and promote VAs. Slow CCs elimination relies in the manual identification of them and ab...
Article
Objective: We proposed and evaluated a method for correcting possible phase shifts provoked by the presence of ventricular premature contractions (VPCs) for a better assessment of T-wave alternans (TWA). Methods: First, we synthesized ECG signals with artificial TWA in the presence of different noise sources. Then, we assessed the prognostic value...
Article
Objective: The aim of this work was to evaluate the potential changes in the ballistocardiogram (BCG) signal induced by different respiratory patterns and posture, by using the dynamic time warping (DTW) technique. Approach: BCG signals were recorded in a group of 20 healthy volunteers, simultaneously to the ECG. Two recordings, one in supine (S...
Article
Full-text available
Objective: This study introduces a predictability framework based on the concept of Granger causality (GC), in order to analyze the activity and interactions between different intracardiac sites during atrial fibrillation (AF). Methods: GC-based interactions were studied using a three-electrode analysis scheme with multi-variate autoregressive m...
Article
Full-text available
Background Patients with chronic heart failure are at high risk of sudden cardiac death (SCD). Increased dispersion of repolarization restitution has been associated with SCD, and we hypothesize that this should be reflected in the morphology of the T‐wave and its variations with heart rate. The aim of this study is to propose an electrocardiogram...
Conference Paper
Chronic heart failure (CHF) and atrial fibrillation (AF) are worldwide leading causes of morbidity and mortality in elders, a large part due to sudden cardiac deaths (SCD). The high irregularity of ventricular response in AF patients makes the use of standard SCD-risk markers inappropriate in this target population. The aim of this study was twofol...
Article
In this paper, an ischemia detector is presented based on the analysis of QRS-derived angles. The detector has been developed by modeling ischemic effects on the QRS angles as a gradual change with a certain transition time and assuming a Laplacian additive modeling error contaminating the angle series. Both standard and non-standard leads were use...
Article
Objective: Heart rate turbulence (HRT) has been successfully explored for cardiac risk stratification. While HRT is known to be influenced by the heart rate (HR) and the coupling interval (CI), non-concordant results have been reported on how the CI influences HRT. The purpose of this study is to investigate HRT changes in terms of CI and HR by me...
Article
Introduction: Not only repolarization, but also depolarization ECG indexes reflect the progression of ischemic injury. The aim was to assess the QRS duration and morphology dynamics during the prolonged coronary occlusion and their association with the myocardial area at risk (MaR) and final infarct size (IS). Methods: In pigs, myocardial infarc...
Article
Instabilities in ventricular repolarization have been documented to be tightly linked to arrhythmia vulnerability. Translation of the information contained in the repolarization phase of the electrocardiogram (ECG) into valuable clinical decision-making tools remains challenging. This work aims at providing an overview of the last advances in the p...
Conference Paper
Full-text available
The study of activation maps using multi-electrode arrays (MEA) can help to understand atrial fibrillation(AF) mechanisms. Activation mapping based on recorded unipolar electrograms (u-EGM) rely on the local activation time (LAT) detector, which has a limited robustness,accuracy, and generally requires manual post-edition. Ingeneral, LAT detection...
Conference Paper
Full-text available
Average TWA activity has been shown to be an independent predictor of sudden cardiac death (SCD) in chronic heart failure (CHF) patients. However, the influence of circadian rhythms on TWA remains understud-ied. In this work, we assessed circadian TWA changes in a CHF population and evaluated whether the prognos-tic value of TWA indices is sensitiv...