VARIABLE RATE PACEMAKER, COUNTER-CONTROLLED, VARIABLE RATE PACER

• US 3,631,860 A
• Filed: 10/27/1969
• Issued: 01/04/1972
• Est. Priority Date: 10/27/1969
• Status: Expired due to Term

• Current Assignee: Warner-Lambert Company (Pfizer Inc.)
• Original Assignee: Michael Lopin
• Inventors: Lopin, Michael
• Primary Examiner(s): Kamm, William E.
• Application Number:
  US04/869,463
• Time in Patent Office: 799 Days
• Field of Search: 128/419P 331/113,179 307/271
• US Class Current: 607/30
• CPC Class Codes: A61N 1/365 controlled by a physiological parameter, e.g. heart potential evoked response A61N1/371
• CPC Class Codes: A61N 1/37217 characterised by the communication link, e.g. acoustic or tactile

Abstract

A variable rate pacer having two flip-flops for defining four possible states. Each state determines the magnitude of a charging current which in turn determines the rate of the pacer. The flip-flops, arranged in a counter configuration, are cycled by a monostable magnetic reed switch which is pulsed by placing an external magnetic field in the vicinity of the patient'"'"''"'"'s chest. The magnetic reed switch is used only for cycling the counter to establish the proper rate of operation; the reed switch is not required for maintaining the charging current once it is established. Reliability of operation is improved because, unlike the prior art, mechanical switches are not required for maintaining the selected charging current level.

Claims

1. A pacer comprising terminal means for connection to a patient'"'"''"'"'s heart and pulse-generating means for applying periodic pulses to said terminal means, said pulse-generating means including multistate electronic circuit means comprising an electronic counter for representing at least two states, normally inoperative pulsing means responsive to the detection of an external signal for changing the state of said multistate electronic circuit means, and means responsive to the state of said multistate electronic circuit means for maintaining a respective rate of operation of said pulse-generating means when said pulsing means is inoperative.

2. A pacer in accordance with claim 1 wherein said pulse-generating means comprises a capacitor-charging timing circuit, and a constant current source for supplying charging current to said timing circuit.

3. A pacer in accordance with claim 1 wherein said respective rate-maintaining means comprises a plurality of individual current-determining sources connected in parallel to and for feeding said constant current source, and means for controlling the operation of respective groups of said individual current-determining sources responsive to respective states being represented by said multistate electronic circuit means.

4. A pacer in accordance with claim 3 wherein said constant current source includes means for summing the currents from said individual current-determining sources and for isolating said timing circuit from said multistate electronic circuit means to prevent the spurious switching thereof.

5. A pacer in accordance with claim 4 wherein said pulsing means includes means comprising a monostable magnetic reed switch for advancing the state of said counter responsive to the closing of said switch.

6. A pacer in accordance with claim 5 further including means for detecting the natural beating of said patient'"'"''"'"'s heart and in response thereto for inhibiting the generation of the next pulse which would otherwise be generated by said pulse-generating means, and means including an additional monostable magnetic reed switch for selectively preventing the inhibiting of the operation of said pulse-generating means, said monostable magnetic reed switch and said additional monostable magnetic reed switch being oriented in said pacer such that each of said switches can be closed independent of the other responsive to the application of a magnetic field having a respective orientation.

7. A pacer in accordance with claim 2 wherein said pulsing means includes mEans comprising a monostable magnetic reed switch for advancing the state of said counter responsive to the closing of said switch.

8. A pacer in accordance with claim 1 wherein said pulsing means includes means comprising a monostable magnetic reed switch for advancing the state of said counter responsive to the closing of said switch.

9. A pacer in accordance with claim 1 wherein said pulsing means includes means for making mechanical contacts.

10. A pacer in accordance with claim 9 wherein said mechanical contacts making means comprises a monostable magnetic reed switch.