A computer-implemented method for analyzing a physiological signal includes selecting a first time interval containing a pattern of interest in a recording of the physiological signal. Respective values of a characteristic of the physiological signal are computed in a plurality of time segments within the first time interval. The computed values are concatenated to form a signature of the pattern of interest. A further occurrence of the pattern of interest is identified in the physiological signal during a second time interval by matching the signal in the second time interval to the signature.