A control device (100) for controlling the rotational speed (nVAD (t)) of a non-pulsatile ventricular assist device, VAD, (50) uses an event-based within-a-beat control strategy, wherein the control device is configured to alter the rotational speed of the VAD within the cardiac cycle of the assisted heart and to synchronize the alteration of the rotational speed with the heartbeat by at least onesequence of trigger signals ([sigma](t)) that is related to at least one predetermined characteristic event in the cardiac cycle. Further, a VAD (50) for assistance of a heart comprises the control device (100) for controlling the VAD, wherein the VAD is preferably a non-pulsatile rotational, for example catheter-based, blood pump.