Emotions are directly related whit external or internal stimulation which a person is submitted, influencing these stimuli on their physical and mental health. These emotional changes produce variations in cardiovascular behavior and respiratory activity. This research proposes the characterization of cardiac system in healthy subject submitted to 3 different audiovisual stimuli, by means of the analysis of Heart Rate Variability (HRV) and upward and downward slopes of the QRS complex. The electrocardiographic signal (3 leads) was recorded from 29 healthy subjects. An audiovisual stimulation protocol was designed. Principal characteristic of ECG signals were extracted. After, a model was designed based on a Fuzzy K Nearest Neighbors classifier to determine different cardiac patterns related to each stimulus. Two classification procedure were performed, the first comparing all groups of stimuli, and the second comparing each pair of stimuli. These comparisons were applied to each obtained characteristic, HRV, and slopes. According to the results, HRV was able to differentiate between basal state and fear, with an area under the curve of 79%. Finally, two new healthy subjects were analysed with the obtained model. The pattern used with HRV and the upward slope of QRS showed clear differences between the propose stimuli.