0000000000033731
AUTHOR
Estrella Blasco
Análisis tiempo-frecuencia de la fibrilación ventricular. Estudio experimental
Introduction and objectives. The analysis of frequency variability during ventricular fibrillation has yielded inconsistent results. We used an experimental model of ventricular fibrillation, with a short timescale, to analyze variations in frequency and their associated spatial distribution. Methods. Epicardial recordings of ventricular fibrillation were made in 10 perfused isolated rabbit heart preparations using a multiple electrode system (i.e., 240 unipolar electrodes). Both spectral and time-frequency analysis were used to derive the dominant frequency in the anterolateral wall of the left ventricle. Results. Linear regression analysis showed that there was a good correlation between …
Changes in the Spectral Characteristics of Ventricular Fibrillation in Lesions Produced by Radiofrequency Ablation. An Experimental Study
INTRODUCTION AND OBJECTIVES Although electro- physiological databases contain information about changes in the time domain in lesions produced by radiofrequency ablation, very few data on changes in the frequency domain are available. The aim of this study was to investigate changes in the spectral characteristics of ventricular fibrillation in zones with radiofrequency lesions. METHODS Recordings of ventricular fibrillation were obtained in 11 isolated perfused rabbit heart preparations using a multiple epicardial electrode located on the left ventricular free wall. Spectral parameters derived by Fourier analysis before and after the creation of transmural radiofrequency lesions were compa…
[Effect of flecainide on longitudinal and transverse conduction velocities in ventricular myocardium. An experimental study].
It is known that the effect of flecainide on longitudinal and transverse ventricular conduction velocities depends on the coupling interval. If this is so, whether the longitudinal or transverse direction is predominantly affected could depend on the magnitude of the coupling interval. In order to investigate this hypothesis, we studied the effect of flecainide, 1 micromol/L, on conduction velocities in excised heart preparations from 11 rabbits using a basal cycle length of 250 ms and inserting two extrastimuli at a decreasing coupling interval. Flecainide significantly reduced both conduction velocities. However, the effect increased as the coupling interval decreased for only the longitu…
Modificaciones de las características espectrales de la fibrilación ventricular en las lesiones producidas con radiofrecuencia. Estudio experimental
Introduccion y objetivos Aunque se dispone de informacion sobre las modificaciones en el dominio del tiempo de los registros electrofisiologicos en zonas lesionadas con radiofrecuencia, los datos disponibles en el dominio de la frecuencia son muy escasos. Se analizan las modificaciones de las caracteristicas espectrales de la fibrilacion ventricular en zonas lesionadas con radiofrecuencia. Metodos En 11 preparaciones de corazon aislado y perfundido de conejo, se registra la fibrilacion ventricular con un electrodo multiple epicardico situado en la pared libre ventricular izquierda. Se comparan los parametros espectrales obtenidos mediante analisis de Fourier antes y despues de practicar les…
Efectos de la flecainida sobre las velocidades de conducción longitudinal y transversal en el miocardio ventricular. Estudio experimental
Es conocido que el efecto de la flecainida sobre las velocidades de conduccion ventricular longitudinal y transversal depende del acoplamiento entre estimulos. Si esto es asi, el predominio de los efectos en sentido longitudinal frente al transversal puede variar en funcion de dicho acoplamiento. Con el objetivo de analizar dicha hipotesis, se ha estudiado el efecto de la flecainida (1 μmol/l) sobre dichas velocidades de conduccion en 11 preparaciones de corazon aislado de conejo, para lo que se ha utilizado un tren base de estimulacion de 250 ms y se han acoplado 2 extraestimulos con acoplamiento decreciente. La flecainida ha reducido ambas velocidades de forma significativa. Este efecto s…
Dofetilide effects on the inhibition by trains of subthreshold conditioning stimuli.
We investigated the electrophysiological actions of dofetilide upon the ventricular myocardium to determine whether the drug modifies the inhibitory effects of subthreshold stimuli trains upon ventricular refractoriness. In nine Langendorff perfused rabbit hearts, ventricular epicardial electrodes were used to determine the following parameters at baseline and during dofetilide perfusion (0.5 micromolar): effective (ERP) and functional (FRP) refractory periods, conduction velocity (CV), wavelength (WL), and ERP prolongation (inhibitory effect) induced by subthreshold stimuli trains (STr) at pulse frequencies of 100, 300, and 600 Hz. Dofetilide significantly prolongs ventricular refractorine…