A cardiac device is provided comprising a measuring electrode (3), a signal-processing unit (41,87) and a post-processing unit (43,45). The measuring electrode (3) is adapted to be positioned within the blood pool (16) of a human or an animal heart (1), in order to measure an depolarization-signal (61). The signal-processing unit (41,87) is connected to the measuring electrode (3) and is adapted to remove signal components with frequencies lower than a cut-off frequency from the measured depolarization-signal (61). The post-processing unit (43,5) is connected to the signal-processing unit (41,87) and is adapted to determine, based on the Brody effect, a measure (46) for a ventricular volume of the heart (1) based on the modified depolarization-signal (42； 5). Furthermore, a method for the determination of a measure for a ventricular volume of a heart (1) and a computer program product for performing the steps of this method are provided.
