The stimulator has a sensing unit for detecting intrinsic cardiac activities of a ventricle. A ventricular stimulation unit stimulates another ventricle. The stimulation unit processed output signals of the sensing unit and generates control signals. A stimulation control unit derives a current intrinsic interval from detected cardiac activities and determines a delay interval from the intrinsic interval. The delay interval begins with a ventricular event of the former ventricle and ends with trigger of a stimulation of the latter ventricle by the control unit.
