Some embodiments described herein relate to a method that includes defining an electro-anatomical model of a heart. The electro-anatomical model can include conduction patterns for multiple patterns or phases identified by a measurement instrument. The electro-anatomical model can also include a voltage map of the heart. A portion of the heart containing a rotor can be identified based on circulation in one phase of the model. The rotor can be determined to be stable based on that portion of the heart having circulation in another phase of the model. The rotor can be characterized as a substrate rotor based on the rotor being stable and based on the voltage or a change in voltage at the portion of the heart containing the rotor. The rotor can be treated or ablated when the rotor is determined to be a substrate rotor.
