Spectral Analysis and Mutual Information Estimation of Left and Right Intracardiac Electrograms during Ventricular Fibrillation.

Ventricular fibrillation (VF) signals are characterized by highly volatile and erratic electrical impulses, the analysis of which is difficult given the complex behavior of the heart rhythms in the left (LV) and right ventricles (RV), as sometimes shown in intracardiac recorded Electrograms (EGM). However, there are few studies that analyze VF in humans according to the simultaneous behavior of heart signals in the two ventricles. The objective of this work was to perform a spectral and a non-linear analysis of the recordings of 22 patients with Congestive Heart Failure (CHF) and clinical indication for a cardiac resynchronization device, simultaneously obtained in LV and RV during induced VF in patients with a Biventricular Implantable Cardioverter Defibrillator (BICD) Contak Renewal IVTM (Boston Sci.). The Fourier Transform was used to identify the spectral content of the first six seconds of signals recorded in the RV and LV simultaneously. In addition, measurements that were based on Information Theory were scrutinized, including Entropy and Mutual Information. The results showed that in most patients the spectral envelopes of the EGM sources of RV and LV were complex, different, and with several frequency peaks. In addition, the Dominant Frequency (DF) in the LV was higher than in the RV, while the Organization Index (OI) had the opposite trend. The entropy measurements were more regular in the RV than in the LV, thus supporting the spectral findings. We can conclude that basic stochastic processing techniques should be scrutinized with caution and from basic to elaborated techniques, but they can provide us with useful information on the biosignals from both ventricles during VF.

[The efficacy of scheduled cardioversion in atrial fibrillation. Comparison of two schemes of treatment: electrical versus pharmacological cardioversion]. / Eficacia de la cardioversión programada en la fibrilación auricular. Comparación de dos esquemas de tratamiento: cardioversión eléctrica frente a cardioversión farmacológica.

INTRODUCTION AND OBJECTIVES: Atrial fibrillation is an arrhythmia with high morbidity and mortality. Restoring sinus rhythm is one of the principle objectives in its management. The present study aimed to assess the efficacy of scheduled cardioversion on atrial fibrillation by comparing two different therapeutic approaches: electrical vs. pharmacological cardioversion. PATIENTS AND METHOD: Two hundred thirty patients with atrial fibrillation of more than 48 hours duration and requiring sinus rhythm restoration were included. One hundred forty-four patients underwent external electrical cardioversion and 86 patients received quinidine. We analyzed the rate of success, duration of hospital stay, complications and clinical and echocardiographic variable that might predict success. RESULTS: Sinus rhythm was restored in 181 of 230 patients (79%). The rate of success was 77% (111/144 patients) in the electrical group and 81% (70 of 86 patients) in the pharmacological group (ns). In 13 pharmacological group patients for whom the first attempt failed attempt, a second attempt with electrical cardioversion was made and was successful in 8 patients (61%). No embolic complication was recorded and only two electrical disturbances were seen. Only atrial fibrillation lasting less than 8 weeks was associated with a higher success rate (p < 0.01). CONCLUSIONS: Scheduled cardioversion in atrial fibrillation is an effective technique with a high success rate and a very low rate of complication. Electrical cardioversion and pharmacological cardioversion with quinidine are similarly effective, although the latter involves a longer hospital stay.

Eficacia de la cardioversión programada en la fibrilación auricular. comparación de dos esquemas de tratamiento: cardioversión eléctrica frente a cardioversión farmacológica / The Efficacy of Scheduled Cardioversion in Atrial Fibrillation. Comparison of Two Schemes of Treatment: Electrical versus Pharmacological Cardioversion

Introducción y objetivos. La fibrilación auricular es una arritmia con una elevada morbimortalidad. Restablecer el ritmo sinusal es uno de los objetivos principales en su manejo. El objetivo del presente estudio es evaluar la eficacia de la cardioversión programada en la fibrilación auricular comparando dos estrategias: la cardioversión eléctrica y la farmacológica. Pacientes y método. Se incluyeron 230 pacientes consecutivos con fibrilación auricular de más de 48 h de evolución tributarios de intento de reversión a ritmo sinusal. En 144 casos se realizó cardioversión eléctrica externa y en 86 farmacológica con quinidina, analizándose el porcentaje de éxito alcanzado, la estancia hospitalaria, las complicaciones y una serie de variables clínicas y ecocardiográficas que permitieran predecir un mayor éxito en la cardioversión. Resultados. Se consiguió restablecer el ritmo sinusal en 181 de 230 pacientes (79 por ciento). En el grupo eléctrico el porcentaje de éxito fue del 77 por ciento (111/144 casos) y en el grupo farmacológico del 81 por ciento (70/86 casos; p = NS).En 13 pacientes del grupo farmacológico en los que fracasó el primer intento se realizó posteriormente cardioversión eléctrica, que fue eficaz en 8 casos (61 por ciento). No se produjo ninguna complicación embólica y sólo dos eléctricas. Únicamente la presencia de una duración de la fibrilación auricular menor de 8 semanas se asoció a un mayor éxito (p < 0,01).Conclusiones. La cardioversión programada en la fibrilación auricular es una técnica eficaz, con una alta tasa de éxitos y un muy bajo índice de complicaciones. La eficacia es similar entre la cardioversión eléctrica y la farmacológica, aunque con una mayor estancia hospitalaria en el grupo farmacológico (AU)