| 摘要 |
1285920 Electromedical apparatus. HEWLETT PACKARD CO 19 Dec 1969 [23 Dec 1968] 62007/69 Heading G1N In apparatus for monitoring and analyzing ECG waveforms, the widths of the QRS portions of the waveform are determined and compared with a stored reference value of the normal QRS width, an indication being given if a QRS portion is too wide and also if a QRS portion is too early. The trend of such abnormal beats, i.e. the number occurring in sequence, may be monitored and alarms operated if the frequency of abnormal beats exceeds a threshold. Spurious signals e.g. due to interference, electromyographic noise, D.C. signals from the electrodes, may be detected and rejected and the apparatus may be connected to a remote recording system. As described, in Figs.1-4 (not shown) which are inter-connected, the rectified derivative of a received ECG waveform is compared with a pre-set threshold level signal which is set by an AGC circuit (37) and when the QRS portion of this waveform exceeds this level an output pulse of width equal to the QRS portion is produced by a pulse-stretching circuit (45), provided the first excursion of the threshold level is at least 15 m. sec. and that any drop below the level between the first and last excursion is no more than 90 m. secs. For the duration of this output pulse an oscillator (47) produces constant frequency pulses which are counted in a counter (49). At the end of a first operating period, i.e. the storage cycle, the count in (49) is transferred to a register (51). Subsequent QRS portions then produce further counts in counter (49) which are each compared with the reference count in (51), an indication on a lamp (61) being given if a QRS portion is too wide. Too early beats are indicated on a lamp (83).
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