Cardiac pacemaker having integrated pacing lead and oxygen sensor

• US 5,411,532 A
• Filed: 06/04/1993
• Issued: 05/02/1995
• Est. Priority Date: 06/04/1993
• Status: Expired due to Term

• Current Assignee: Pacesetter Incorporated (Abbott Laboratories)
• Original Assignee: Pacesetter Incorporated (Abbott Laboratories)
• Inventors: Mortazavi, Said
• Primary Examiner(s): Kamm, William E.
• Assistant Examiner(s): Getzow, Scott M.
• Application Number:
  US08/073,225
• Time in Patent Office: 697 Days
• Field of Search: 607/22, 607/122
• US Class Current: 607/22
• CPC Class Codes: A61N 1/36557 controlled by chemical substances in blood

Abstract

An improved cardiac pacemaker system of the kind that includes an oxygen sensor implantable into a patient'"'"'s blood stream along with one or two electrical conductors for use in sensing heart beat activity and in selectively applying pacing pulses to the heart muscle. In an embodiment having just one implantable conductor, the oxygen sensor is integrated into the conductor, while in an embodiment having two implantable conductors, the oxygen sensor either is integrated into one of the conductors or is connected between the two conductors, in parallel with the heart muscle. In both cases, the oxygen sensor is selectively used without adversely affecting either heart beat sensing or pacing.

Claims

1. An implantable cardiac pacemaker system including a pulse generator for generating pacing pulses, the system further including:

at least one electrical conductor having a proximal end for electrically interfacing with the pulse generator and a distal end for electrical contact with selected heart muscle,

said pulse generator further selectively coupling pacing pulses along the at least one conductor to electrically stimulate the patient'"'"'s heart muscle;

an oxygen sensor circuit connected in series circuit arrangement with the at least one conductor;

means for generating oxygen sensing pulses; and

an oxygen sensor circuit controller for intermittently coupling oxygen sensing pulses to the oxygen sensor circuit along the at least one conductor for measuring the oxygen content of the patient'"'"'s blood.

2. A cardiac pacemaker system, as defined in claim 1, wherein:

the pacing pulses are of a first polarity; and

the oxygen sensing pulses are of a second polarity, opposite to the first polarity.

3. A cardiac pacemaker system, as defined in claim 2, wherein the oxygen sensor circuit includes a diode connected in series circuit arrangement with the at least one conductor and adapted to conduct current of the first polarity and to block current of the second polarity.

4. A cardiac pacemaker system, as defined in claim 3, and further comprising:

a heart sensor connected in parallel with the pulse generator; and

a resistor connected in parallel with the diode.

5. A cardiac pacemaker system, as defined in claim 4, wherein the oxygen sensor circuit includes an oxygen sensor and the diode is connected in parallel with the oxygen sensor.

6. An implantable cardiac pacemaker system comprising:

a first electrical conductor implantable in contact with a patient'"'"'s heart muscle;

a second electrical conductor implantable in contact within the patient'"'"'s bloodstream, the first and second electrical conductors having electrical voltages thereon as a function of heartbeats;

an oxygen sensor circuit connected to either or both of the first and second electrical conductors and implantable within the patient'"'"'s blood; and

a pacing pulse generator for generating pacing pulses, the pulse generator including

a heart sensor for monitoring the relative voltages present on the first and second electrical conductors, to detect the occurrence of a heart beat, said pulse generator further selectively coupling pacing pulses along the first and second electrical conductors, to electrically stimulate the heart muscle;

an oxygen sensor controller for generating oxygen sensing pulses and for intermittently coupling oxygen sensing pulses along the first and second electrical conductors to the oxygen sensor circuit, to measure the oxygen content of the patient'"'"'s blood, said pacing pulses being of a first polarity; and

the oxygen sensing pulses being of a second polarity, opposite the first polarity; and

wherein the oxygen sensor circuit further comprises;

a diode integrated into either the first conductor or the second conductor, for conducting current of the first polarity and blocking current of the second polarity; and

a resistor connected in parallel with the diode.

7. An implantable cardiac pacemaker system as defined in claim 6, wherein the oxygen sensor circuit further comprises an oxygen sensor connected in parallel with the diode and the resistor.

8. An implantable cardiac pacemaker as defined in claim 6, wherein the oxygen sensor circuit is connected between the first electrical conductor and the second electrical conductor.

9. A body implantable sensor and lead comprising:

an implantable stimulating lead having a connector at one end thereof for interfacing with a desired pacing pulse generator;

an electrode at the other end thereof for contacting selected heart muscle, the stimulating lead including;

an electrical conductor coupled between the connector and the electrode for conducting pacing pulses from the desired pacing pulse generator to the selected heart muscle;

sensor means electrically inserted in series with the conductor for sensing a specific characteristic of body fluid proximal the sensor means, the sensor means responsive to a drive signal for generating an output signal that varies as a function of the specific body fluid characteristic; and

controller means for intermittently transmitting the drive signal and the pacing pulses along the conductor.

10. The body implantable sensor and lead of claim 9, wherein the controller means further comprises means for monitoring the sensor means output signal along the conductor.

11. The body implantable sensor and lead of claim 10, wherein the drive signal is of a first polarity and the pacing pulse is of a second polarity opposite to the first polarity.

12. The body implantable sensor and lead of claim 11, wherein the sensor means comprises a blood oxygen sensor, the body fluid is blood, and the specific characteristic is blood oxygen.

13. The body implantable sensor and lead of claim 12, wherein the sensor means includes a diode coupled to the conductor for conducting current of the first polarity, and for blocking current of the second polarity.

14. The body implantable sensor and lead of claim 13, wherein the oxygen sensor includes means for emitting a measuring signal in the blood in response to the drive signal and means for receiving a portion of said measuring signal reflected back to said oxygen sensor by the blood, the portion of the measuring signal reflected back to said oxygen sensor being proportional to the oxygen content of the blood.

15. A pacemaker lead adapted for transmitting pacing pulses for unipolar pacing, the lead having a single electrical conductor and an oxygen sensor circuit electrically inserted in series with said single electrical conductor, such that pacing pulses transmitted through the single electrical conductor are transmitted through the oxygen sensor circuit.

16. The pacemaker lead of claim 15, wherein the oxygen sensor circuit includes a diode electrically inserted in series with said conductor for conducting current of a first polarity and blocking current of a second polarity which is opposite to the first polarity.

17. The pacemaker lead of claim 16, wherein the oxygen sensor circuit includes a resistor connected in parallel with the diode.

18. The pacemaker lead of claim 17, wherein the oxygen sensor circuit further comprises a blood oxygen sensor connected in parallel with the diode and the resistor.

19. A pacemaker lead adapted for transmitting pacing pulses for bipolar pacing, the lead having two electrical conductors and an oxygen sensor circuit electrically inserted in series with one of said two electrical conductors, such that pacing pulses transmitted through such one of said two electrical conductors are transmitted through the oxygen sensor circuit.

20. The pacemaker lead of claim 19, wherein the oxygen sensor circuit includes a diode electrically inserted in series with said conductor for conducting current of a first polarity and blocking current of a second polarity which is opposite to the first polarity.

21. The pacemaker lead of claim 20, wherein the oxygen sensor circuit includes a resistor connected in parallel with the diode.

22. A pacemaker lead for delivering pacing pulses from a desired pacing pulse generator to a desired location in the heart, comprising:

first and second electrical conductors;

means for electrically interfacing the first and second electrical conductors with the pulse generator;

a ring electrode;

a tip electrode, one of said first and second conductors coupled from the interfacing means to one of said ring and tip electrodes, the other one of said first and second conductors coupled from the interfacing means to the other one of said ring and tip electrodes; and

a blood oxygen sensor circuit inserted in series circuit arrangement with either one of said first and second conductors, such that pacing pulses pass through the blood oxygen sensor circuit.

23. A pacemaker lead for delivering pacing pulses from a desired pacing pulse generator to a desired location in the heart, the lead comprising:

first and second electrical conductors;

means for electrically interfacing the first and second electrical conductors with the pulse generator;

a ring electrode;

a tip electrode, one of said first and second conductors coupled from the interfacing means to one of said ring and tip electrodes, the other one of said first and second electrodes coupled from the interfacing means to the other one of said ring and tip electrodes;

a diode inserted in series circuit arrangement with either one of said first and second conductors;

a resistor in parallel circuit arrangement with the diode; and

a blood oxygen sensor electrically coupled to and in parallel circuit arrangement with the first and second conductors.