A device is provided for monitoring the integrity of a flow circuit in fluid communication with a receptacle. The flow circuit comprises a pumping device for transferring fluid through the flow circuit. The device operates according to a monitoring method in which a pressure signal is received from a pressure sensor, the pressure signal being indicative of fluid pressure in the receptacle or the flow circuit. The pressure signal is then processed for detection of a beating signal. The beating signal manifests itself as an amplitude modulation of the pressure signal and is formed by interference between pressure waves generated by a pulse generator associated with the receptacle and pressure waves generated by the pumping device. The integrity of the flow circuit is determined based at least partly on the presence or absence of the beating signal. The device and the flow circuit may be part of an apparatus for extracorporeal blood treatment, and the method may be implemented as a computer program product.