ECG periodic components as a promising tool for complexity assessment during stepwise ablation of atrial fibrillation

Introduction: Stepwise radiofrequency catheter ablation (step-CA) has become a treatment of choice for the restoration of sinus rhythm (SR) in patients (pts) with long-standing persistent atrial fibrillation (pers-AF). Its success rate appears limited as the amount of ablation to achieve long term SR is unknown. Recently, intracardiac organization indices (OI) of AF have been used to track the efficiency of step-CA, with limited success. Our study is aimed at developing new OIs based on the relationships between harmonic components of atrial activity from the surface ECG as a global assessment of AF complexity and organization during step-CA. Methods: 3 pts with pers-AF (age 62, AF duration 17 months) underwent a step-CA. An adaptive tracking algorithm was developed for estimating the instantaneous frequency of atrial activity on chest lead V1 (after QRST subtraction) and for extracting its fundamental and harmonic components. An adaptive organization index (AOI) was computed as the ratio between the power of the extracted components and the total power of the signal to evaluate the temporal evolution of AF oscillations. The variance of the phase difference (PD) between the fundamental and harmonic components was used for measuring AF regularity. Results: Step-CA terminated 2/3 pers-AF into flutter. Importantly, in the 2 terminated pts, the AOI did not show any significant change during the step-CA (from pre-ablation to CFAE), while the PD showed a gradual reduction suggestive of increased coupling between the fundamental and the 1st harmonic. See figure. Conclusions: The PD and the AOI as measurements of complexity from the surface ECG appear as promising methods for tracking the effect of step-CA on global AF organization. This, however, needs to be validated on a larger population

A New Method for ECG Tracking of Persistent Atrial Fibrillation Termination during Stepwise Ablation

Stepwise radiofrequency catheter ablation (step-CA) has become the treatment of choice for the restoration of sinus rhythm (SR) in patients with long-standing persistent atrial fibrillation (pers-AF). Its success rate appears limited as the amount of ablation to achieve long term SR is unknown. Multiple organization indexes (OIs) have been previously developed to track the organization of AF during step-CA, however, with limited success. We report an adaptive method for tracking AF termination (AF-term) based on OIs characterizing the relationship between harmonic components of atrial activity from the surface ECG of AF activity. By computing their relative evolution during the last two steps preceding AF-term, we found that the performance of our OIs was superior to classical indices to track the efficiency of step-CA “en route” to AF-term. Our preliminary results suggest that the gradual synchronization between the fundamental and its first harmonic of AF activity appears as a promising parameter for predicting AF-term during step-CA

Ciencia en Sociedad. Reflexiones en el marco de su relación bidireccional

Con autorización de la editorial para este libro. La edición de este libro estuvo a cargo de Jesús Rey Rocha y Víctor Ladero.Este libro surge como una iniciativa para compilar una serie de artículos alumbrados a partir de la génesis del Grupo CURIE (Científic@s Unid@s por la Reactivación de la Investigación en España), semilla de la Asociación Española para el Avance de la Ciencia (AEAC). Durante meses sus miembros estuvieron intercambiando reflexiones y debatiendo sobre la distancia entre la ciencia y la sociedad, y la necesidad de crear una asociación que llenase ese vacío entre los científicos y los ciudadanos, que apostase por llevar la ciencia y los conocimientos generados por la misma a toda la sociedad, tal y como establecen la Declaración de Derechos Humanos y la Constitución Española, en su artículo 44.Peer reviewe

Fact And Value In Bioethics: How To Get Rid Of The Dichotomy

Este artículo ofrece una perspectiva sobre el desarrollo reciente de la bioética, un campo en el que es habitual distinguir entre hechos y valores. Examinando cómo se usa la palabra valor en la ética biomédica más extendida internacionalmente, se muestra que algunos usos refuerzan cierta tendencia esencialista a tratar los valores como si fueran entidades independientes. Como ilustración y explicación de la creciente importancia de este fenómeno, describimos el lenguaje de los valores en la obra reciente de Diego Gracia, mostrando cómo su propuesta metodológica para la bioética emplea la dicotomía entre hechos y valores, y analizándola en relación con la de George Khushf para articular el debate sobre los conceptos de salud y enfermedad. Concluimos sugiriendo una manera alternativa de concebir los valores que permita superar esa dicotomía

Markers for risk to develop atrial fibrillation based on a new electrocardiographic tool

Atrial fibrillation (AF) is the most important trigger for heart failure and stroke. Reliable methods for predicting AF are lacking and ECG analysis could improve this process. P-wave characteristics in the ECG are an important source of information in the diagnosis of atrial conduction pathology. In our study, we investigate different markers resulting from ECG analysis for detecting AF early stages. Methods: our database consists of 48 ECG from healthy patients (group N, age: 45 to 75 y) , 5 ECG from healthy patients (group B, age: 75 to 85 y) and a third group of 17 ECG from patients with AF history (group AF, age: 48 to 72 y). All the measurements were acquired in sinus rhythm. The ECG recording duration for each patient was of 5 minutes (sampling frequency: 1 KHz). Pre-processing was applied in order to reduce the noise and baseline wander. The P-wave was detected on lead V1 which provided information concerning intra-atrial conduction delays. Several P-wave characteristics were extracted: 1) P width, 2) P-R interval for all beats and 3) the variance of the beat-to-beat P-wave Euclidean distance, measuring P-wave time stability. Results: no significant differences between the groups were obtained using the P-R interval (100±33 ms, 89±41 ms, 106±38 ms, p=ns) and using the P width (120±18 ms, 111±19 ms, 124±24 ms, p=ns). The variance of the beat-to-beat P-wave Euclidean distance was higher for the AF group as compared to N and B groups (0.23±0.12, 0.26±0.26, 0.46±0.32, p<0.001). Conclusions: the Euclidean distance appears as a promising marker for the recognition of patients prone to AF, but it should be combined with other markers in order to improve patient classification

Comités 2.0: deberes, posibilidades y desafíos de la ética institucionalizada en el s. XXI

Ethics committees are one of the main agents in the governance of science and technology, especially in the field of health care. This paper analyses some aspects of their nature, which show the internal relationship between the moral and the scientifictechnological domains. Being both knowledge providers and users thereof, ethics committees deliberate and decide on complex contemporary ethical issues. To pursue their aims, they require adequate technical tools in order to deliberate and choose using new technologies of communication and information. These tools carry new problems with themselves, so committees must acquire a mixed nature, dynamic, interdisciplinary and inclusive. Ethics committees do not only constitute a control device, rather they are an interactive means for the creation of value in society.Los comités de ética son uno de los principales agentes en la gobernanza de la ciencia y la tecnología, especialmente en el ámbito sanitario. Este artículo analiza algunos aspectos de su naturaleza como prueba de la interconexión entre lo moral y lo científico-tecnológico. Como productores de conocimiento y usuarios del mismo, los comités deliberan y deciden sobre complejas cuestiones éticas contemporáneas. Para ejercer sus funciones, requieren medios técnicos adecuados, que permitan deliberar y elegir mediante las nuevas tecnologías de la información y la comunicación. Estos medios traen consigo nuevos problemas, por lo que los comités han de ser de naturaleza mixta, dinámica, interdisciplinar e inclusiva. Los comités de ética no sólo constituyen un mecanismo de control, sino un medio interactivo de generación de valores en la sociedad

Los bosques nos hablan de evolución y cooperación

Peer reviewe

High pre-ablation ECG organization in long-standing persistent atrial fibrillation terminated within the left atrium

The outcome of stepwise catheter ablation (step-CA) for patients (pts) with long-standing atrial fibrillation (LS-pAF) is poorly predicted by classical organization indices (OI). Our study aims at developing new indices from pre-ablation ECG in order to identify the site of AF termination during step-CA. Methods: 23 consecutive pts (59±7y, AF duration 19±12m) underwent step-CA consisting in pulmonary veins isolation, left atrial (LA) defragmentation, and right atrial (RA) ablations for non terminated AF. Chest lead V6 was placed on pts’ back within the cardiac silhouette (V6b). QRST cancellation was performed on chest leads V1 and V6b. Using an adaptive harmonic frequency tracking scheme, two indices were computed to quantify the harmonic components of atrial activity: 1) PD, phase difference between the AF dominant frequency (DF) and its 1st harmonic measuring AF regularity, and 2) AOI, an adaptive OI tracking AF temporal evolution. Both indices were compared to two classical OIs: 1) SOI, ratio of the DF power and its 1st harmonic to the total power (3-15 Hz) and 2) AFCL, ECG AF cycle length. Results: LS-pAF was terminated in 83% (19/23) of the pts: 17 during LA (LT); 2 during RA ablation (RT); 4 were not terminated (NT). The figure shows that AOI on lead V1 (panel A) and PD on lead V6b (panel B) improved the separation between LT and RT/NT pts compared to SOI and AFCL respectively. AFCL was not significantly different between the two groups. Conclusions: Our results suggest that adaptive measures of AF organization computed from pre-ablation ECG perform better than classical indices for identifying pts whose AF will terminate during ablation within the LA. These finding are indicative of a higher baseline organization in these pts that could be used to select LS-pAF candidates for step-CA

Termination of atrial fibrillation by catheter ablation can be successfully predicted from baseline ECG

Purpose Multiple organization indices (OIs) have been used to predict the outcome of stepwise catheter ablation (step-CA) in long-standing persistent AF (pers-AF), however with limited success. Our study aims at developing innovative OIs from baseline (BL, before ablation) ECG in order to predict the outcome of step-CA. Methods Fourteen consecutive patients (pts) (60±5 y, AF duration 21±9 m) underwent a step-CA consisting in pulmonary veins isolation, left atrial (LA) defragmentation and linear ablations, and right atrial (RA) ablations if non terminated. Chest lead V6 was placed in the back (V6b). After QRST cancellation from chest leads V1 to V6b, two OIs were computed to quantify the harmonic components of ECG atrial activity: 1) phase difference variance (PD) between the AF harmonic components as a measure of AF regularity, and 2) adaptive OI (AOI) evaluating the time evolution of the AF harmonic components. Both indices were compared to classical ones: a spectrum-based OI (SOI) and ECG AF cycle length (AFCL). Results Pers-AF was terminated into sinus rhythm or atrial tachycardia in 10/14 pts during step-CA, 8 during LA (LT), 2 during RA (RT) ablation, and 4 were non terminated (NT). The figure shows that LT was best separated from RT/NT before ablation by AOI computed on lead V1 (A) and PD from lead V6b (B) as compared to SOI and AFCL respectively. Conclusion Our results suggest that adaptive OIs computed before ablation perform better than classical OIs for separating LT from RT/NT pts. These findings are indicative of a higher baseline organization in LT pts that could be used to select candidates for the restoration of sinus rhythm by step-CA