| 摘要 |
A multi-mode pacemaker includes a microprocessor 100 and a memory 102 programmable with a variety of processes for stimulating a heart and/or a sensing and transmitting to an external device conditions of the heart or pacemaker. The microprocessor controls a multiplexer 106 to input via a scaling amplifier and a/d converter 108 signals from atrial and ventricular leads 17, 19, the power source 126, a reed switch 23 operable by an external magnet, or redundant leads on lines 138d,e. The output comprises latch drivers 134 a-d with respective output select switches 130 a-d selectively operable to supply stimulation pulses to the leads or allow sensing. External apparatus 104 may transmit coded information to change the stored program or operation of the reed switch may select a different program starting address. Pulse width, rate and amplitude may be controlled in response to sensed heart activity or power source level and different pacing modes (demand, asynchronous, etc.) or multi-site pacing to disrupt arrhythmias may be selected automatically or externally. In an aid converter 308 (Figure 8), counter 400 counts up the output of VCO 402 controlled by unknown signal V(X) and then counts down to zero the output of VCO 402 then controlled by reference EREF and during such countdown a counter 412 counts clock pulses so that when counter 400 reaches zero the output of counter 412 depends on V(X) but not on the scale factor of VCO 402. <IMAGE> |
