This bachelor thesis deals with design and construction of tool for analysing electrocardiograms. The theoretical part deals with the origin of the action potential, propagation of the action potential through conduction system of the heart, failure of electrical impulse propagation through the con-duction system; different aspects of disorders, which can be found in experimental electrograms recorded from animal isolated hearts (database of electrograms, the Department of Biomedical En-gineering, FEEC, BUT), are also discussed. Software for electrograms draw and annotation available on the DBME, namely EG_Anotation and EG_RR_View, are described. As a result, the design and construct of ECG_ANN, the tool for the electrograms annotation, is ...