Resumen─ La fibrilacion auricular (FA) es la arritmia cardiaca mas comun. La ablacion con cateter se ha convertido en la principal estrategia terapeutica para el tratamiento de la FA paroxistica, sin embargo, los resultados en FA permanente no son completamente satisfactorios. Se propone la ablacion de los electrogramas auriculares complejos fragmentados (CFAE) para la terminacion de un rotor como mecanismo de mantenimiento de FA permanente. El objetivo de este trabajo es caracterizar los CFAE mediante la implementacion de entropia aproximada (ApEn) y correlacionarlos con el tip de un rotor simulado. Para esto, se desarrollo un modelo 2D de tejido de auricula humana bajo condiciones de FA permanente; se registraron electrogramas unipolares durante la actividad del rotor y se desarrollo un algoritmo para la medida de ApEn. La ApEn permitio localizar los CFAE con una alta precision y relacionarlos con el tip del rotor. Por lo que este indice podria ser muy eficaz en la identificacion de zonas susceptibles de ablacion. Abstract — Atrial fibrillation (AF) is the most common cardiac arrhythmia. Catheter ablation has become the main therapeutic strategy for the treatment of paroxysmal AF, however, results in permanent AF are not completely satisfactory. Ablation of complex fractionated atrial electrograms (CFAE) is proposed for the termination of a rotor as mechanism of permanent AF maintenance. The aim of this work is to characterize the CFAE by implementing approximate entropy (ApEn) and to correlate with the tip of a simulated rotor. For this, a 2D model of human atrial tissue under permanent FA conditions was developed. Unipolar electrograms were recorded during the rotor activity and an algorithm to measure ApEn was developed. The ApEn allowed locate the CFAE with high precision and relate them to the tip of the rotor. So this index could be very effective in identifying target sites for ablation.