Determining stability of a catheter is described. A first signal originating from a first region of a patient is monitored and a second signal originating from a second region of the patient is monitored. First components from a recurring interval of the second signal are extracted, where the recurring interval is defined by the first signal. The first components are compared to determine a first similarity value of the first components over time. The first similarity value is compared to a threshold value to determine a stability evaluation for a source of the second signal.
