Abstract: A controller for a pacing device, configured to; receive sensor data comprising respiratory data; determine a respiratory sinus arrhythmia, RSA, factor of a pacing signal based on the sensor data; determine a cardio-respiratory phase synchronisation, CRPS, factor of the pacing signal based on the sensor data; and provide the pacing signal for pacing a heart of a patient in accordance with the RSA factor and the CRPS factor.

Abstract: The disclosure relates to determining timing of electrical stimulus signals temporally modulated by a respiration signal. Aspects of the disclosure relate to an apparatus comprising: a first input stage configured to receive a first input signal indicative of respiration; a respiration analysis module configured to determine, from the first input signal, a signal indicative of instantaneous respiration duty cycle; and a synchronization module configured to generate the timing of the stimulus signals as a function of the signal indicative of respiration duty cycle in order to maintain a bias towards synchronization between the respiration period and an integer ratio of the periods between stimulus signals.