Evaluation of the Complexity of Myocardial Activation During Ventricular Fibrillation. An Experimental Study

A B S T R A C T Introduction and objectives: An experimental model is used to analyze the characteristics of ventricular fibrillation in situations of variable complexity, establishing relationships among the data produced by different methods for analyzing the arrhythmia. Methods: In 27 isolated rabbit heart preparations studied under the action of drugs (propranolol and KB-R7943) or physical procedures (stretching) that produce different degrees of change in the complexity of myocardial activation during ventricular fibrillation, use was made of spectral, morphological, and mapping techniques to process the recordings obtained with epicardial multielectrodes. Results: The complexity of ve…

Effect of chronic exercise on myocardial electrophysiological heterogeneity and stability. Role of intrinsic cholinergic neurons: A study in the isolated rabbit heart

[EN] A study has been made of the effect of chronic exercise on myocardial electrophysiological heterogeneity and stability, as well as of the role of cholinergic neurons in these changes. Determinations in hearts from untrained and trained rabbits on a treadmill were performed. The hearts were isolated and perfused. A pacing electrode and a recording multielectrode were located in the left ventricle. The parameters determined during induced VF, before and after atropine (1 mu M), were: fibrillatory cycle length (VV), ventricular functional refractory period (FRPVF), normalized energy (NE) of the fibrillatory signal and its coefficient of variation (CV), and electrical ventricular activatio…

Dominant frequency and complexity of electrical reentrant activation during ventricular fibrillation with releasing of NO after acute local stretching. A study in isolated rabbit heart

Estudio experimental de los efectos de EIPA, losartán y BQ-123 sobre las modificaciones electrofisiológicas inducidas por el estiramiento miocárdico

Resumen Introduccion y objetivos Se han implicado diversos mecanismos en la respuesta mecanica al estiramiento miocardico, que incluyen la activacion del intercambiador Na+/H+ por acciones autocrinas y paracrinas. Se estudia la participacion de estos mecanismos en las respuestas electrofisiologicas al estiramiento agudo miocardico mediante el analisis de los cambios inducidos con farmacos. Metodos Se analizan las modificaciones de la fibrilacion ventricular inducidas por el estiramiento agudo miocardico en corazones de conejo aislados y perfundidos utilizando electrodos multiples epicardicos y tecnicas cartograficas. Se estudian 4 series: control (n = 9); durante la perfusion del antagonist…

Effect of chronic exercise and ATP-sensitive potassium channel blockade on the spectral characteristics evolution of ventricular fibrillation in acute regional ischemia

Purpose: It has been proposed that chronic exercise produces a KATP channel blockade in ischemic myocardium. We have also reported that channel blockade and training exert very similar effects on energy required to defibrillate. In fact it is postulated that one mechanism by which exercise exerts an antiarrhythmic effect, is by blocking KATP channel. We have analyzed the evolution of spectrum characteristics of ventricular fibrillation (VF), in normoxic conditions and after acute myocardial ischemia, in isolated hearts from trained rabbits, and in hearts submitted to KATP channel blockade. Our hypothesis is that the spectrum characteristics of VF evolve similarly in trained hearts and in he…

Experimental Study of the Effects of EIPA, Losartan, and BQ-123 on Electrophysiological Changes Induced by Myocardial Stretch

[ES] Introducción y objetivos Se han implicado diversos mecanismos en la respuesta mecánica al estiramiento miocárdico, que incluyen la activación del intercambiador Na+/H+ por acciones autocrinas y paracrinas. Se estudia la participación de estos mecanismos en las respuestas electrofisiológicas al estiramiento agudo miocárdico mediante el análisis de los cambios inducidos con fármacos. Métodos Se analizan las modificaciones de la fibrilación ventricular inducidas por el estiramiento agudo miocárdico en corazones de conejo aislados y perfundidos utilizando electrodos múltiples epicárdicos y técnicas cartográficas. Se estudian 4 series: control (n = 9); durante la perfusión del antagonista d…

Evaluación de la complejidad de la activación miocárdica durante la fibrilación ventricular. Estudio experimental

Resumen Introduccion y objetivos Analizar en un modelo experimental las caracteristicas de la fibrilacion ventricular en situaciones con distintos grados de complejidad y establecer la relacion existente entre los datos aportados por distintos metodos de analisis de la arritmia. Metodos En 27 preparaciones de corazon aislado de conejo estudiadas bajo la accion de farmacos (propranolol y KB-R7943) o procedimientos fisicos (estiramiento) que causan distintos grados de variacion de la complejidad de la activacion miocardica durante la arritmia, se han utilizado tecnicas espectrales, morfologicas y cartograficas para procesar los registros obtenidos con multielectrodos epicardicos. Resultados L…