This paper discusses the feasibility and effectiveness of using vectors of the current dipoles representing local electric activity inside the atrial myocardium during atrial fibrillation. The application relates to the search for improving the performance of electric signals observed on the body surface in the diagnoses of this life-threatening arrhythmia. The topics addressed include some historical and basic conceptual notes on the use of the vector, as well as some recent developments in which the vector concept is used in combination with spectral analysis. The invited paper is of a didactic nature.