| 摘要 |
<p>PACER WITH AUTOMATICALLY VARIABLE A-V INTERVAL An improved atrial synchronous heart pacer includes means for generating an atrio-ventricular (A-V) interval control signal of automatically variable duration, which duration is a function of the sensed atrial heart rate (i.e. P-wave rate). A timing circuit establishes a basic timing interval for the generation of ventricular stimulation pulses, which interval may be modified by the control of the A-V interval signal. The A-V interval control signal preferably comprises the output of a P-wave triggered monostable multivibrator. The time constants of the multivibrator's timing circuits are scaled such that operation within the heart-rate range of 55-150 beats per minute prevents full recovery of the multivibrator following each sensed atrial beat and generation of an A-V output pulse, resulting in an A-V output pulse whose duration is a function of the time since the preceding trigger (i.e. rate) By appropriately coupling the variable duration A-V interval pulse to the ventricular stimulation pulse timing circuitry, it is possible to adjust the threshold voltage of a relaxation oscillator such that the ventricular stimulation pulse is generated at the end of an A-V delay following a sensed P-wave, the interval of the A-V delay being variable and dependent on the P-wave rate.</p> |
