pass filter 27 preferably a wien filter a regulator 65 controlled by the pertinent duration meter 28 for adjusting of the selective frequency to precisely double the value of the heart frequency and always two detectors 33 34 series connected to the wien filter for determining the phase 29 30 and amplitude 31 32 of the systolic and diastolic peak of the blood pressure the measuring cycle transmitter 21 is enabled by way of the on off switch 57 it contains a monostable multivibrator 66 preferably with a scanning time of about 2 minutes an astable multivibrator 67 with about the same duration of the cycle an electronic counter 11 controlled by the electrocardiogram or blood pressure an and gate 68 for connecting the outlets of the monostable multivibrator 66 and of the counter 11 as well as an or gate 69 for connecting the outlets of the astable multivibrator 67 and of the and gate 68 as a result of that the blocking 12 of the pump function becomes possible by way of line 59 the changeover switches 70 71 located in the calculator 20 are also controlled via this line 59 the calculator 20 processes the amplitude and phase of the valve closure and or of the systolic pressure peak these characteristic values of the blood pressure will reach either the storages 13 72 for storing of characteristic values while the pump is switched on or the storages 14 73 for storing of the a standard and b theoretical values of blood.