A system including a catheter including multiple, spatially distributed electrodes configured to measure electrical signals of a heart, a system configured to determine a position of the electrodes at multiple, different catheter positions in the heart, and a processing unit for mapping electrical activity in the heart. The processing unit is configured to receive the measured electrical signals from each position of the multiple, different catheter positions and determine whether the measured electrical signals at the position are organized. If the measured electrical signals at the position are organized, the processing unit is configured to determine at least one of velocity vectors, cycle length, and degree of organization at the position from the measured electrical signals.