Recording physiological signals, in particular ECG signals holter recorder, comprising means for detection of disconnection or interruption of the connecting cables

In order to measure the impedance of the line with the connection cable connecting an external electrode placed on a patient to a signal terminal (12) of the recorder (10) generating a current pulse is applied the pulse on said line, measuring the resulting voltage variation on the signal terminal during the duration of application of the current pulse, and determining the impedance of the line from the tension thus measured. According to the invention, the current pulse is a biphasic impulse including two successive cycles of opposite polarities, the durations and amplitudes of these two cycles being selected to define approximately equal respective loads of opposite signs. A switch (36) connects the base of the pull resistor (32) of the signal terminal (12) to the output of a generator (38) of voltage or current during impedance measurement, and connects it to the ground potential (34) the rest of the time.