[EN] This Final Master’s research project focuses its study on the field of bioelectric modelling and simulation, specifically on the development of three-dimensional cardiac models for pediatric patients. Cardiac computational models are an innovative tool which has revolutionized the field of electrophysiology during the last decades. The information and data generated by cardiac simulations provide a wide range of resources for the modernization of the clinical environment, such as personalized medicine, surgical planning, early diagnosis, prevention, etc. Moreover, its relevance in research has been boosted by advances in sensor technology, understanding of biological phenomena, and mathematical and computational processing techniques. Therefore, the development and optimisation of cardiac models is a key issue for the future of biomedical engineering and clinical medicine. The overall objective of this project is to develop a customised computational model of the ventricles and torso using medical magnetic resonance images (MRI) of paediatric patients. To do this, a segmentation process of the ventricular structures will be carried out using Seg3D software, as well as the rest of the main organs and structures of the torso. Then, a volumetric finite element mesh will be generated for each three-dimensional structure to carry out the mathematical simulations using the Elvira software. n these simulations, the ventricular depolarisation process will be reproduced (incorporating a generic Purkinje conduction system) and validated by obtaining the electrocardiogram signals generated by the electrical propagation through the rest of the torso structures. Finally, simulations of pathological depolarisation are carried out, specifically the aim is to recreate a situation of ventricular pre-excitation via accessory pathways. TFGM