| 摘要 |
<p>A sense amplifier for demand cardiac pacemaker of the type having circuitry for providing signals representative of sensed signals and circuitry responsive to the sensed signal representative signal to detect heart activity. Circuitry is provided intermediate the responsive and detecting circuitry for preventing the response of the detecting circuitry for a limited time during and after a pacemaker stimulation signal. In a preferred embodiment a reference level is established which is representative of sensed extraneous repetitive noise. A second level is established which is greater in absolute value than the reference level by an amount representative of sensed heart activity. The detecting circuitry is differentially responsive to the reference and second level for detecting heart activity. The refractory period is established by blocking all signals from the level establishing circuitry for a limited period during and after a pacemaker stimulation signal, that circuitry assuming the quiescent condition during that limited period.</p> |
