Demand pacemaker using an artificial baroreceptor reflex

• US 4,791,931 A
• Filed: 08/13/1987
• Issued: 12/20/1988
• Est. Priority Date: 08/13/1987
• Status: Expired due to Term

• Current Assignee: Pacesetter Incorporated (Abbott Laboratories)
• Original Assignee: Pacesetter Infusion, Ltd. (Siemens AG)
• Inventors: Slate, John B.
• Primary Examiner(s): Coven, Edward M.
• Assistant Examiner(s): Keegan, Timothy
• Application Number:
  US07/085,421
• Time in Patent Office: 495 Days
• Field of Search: 128/419 PG
• US Class Current: 607/24
• CPC Class Codes: A61N 1/36564 controlled by blood pressure

Abstract

A device for use in conjunction with a pulse generator is disclosed which provides a variable pulsing rate in response to short term variations in arterial blood pressure, like the baroreceptor system of the healthy body'"'"'s cardiovascular system. The system utilizes a pressure transducer implanted together with the pacemaker, the transducer is preferably located on the proximal axillary artery. The system features quick response based on physiological need, and also includes a reset feature which maintains a normal resting heart rate despite long term changes in blood pressure.

Claims

1. A cardiac pacemaker for stimulating a heart to beat at a rate which is variable in response to physiological need, comprising:

a pulse generator for generating periodic electrical pulses at a rate determined by a rate input signal supplied to said pulse generator;

a pacing lead for delivering said periodic electrical pulse generated by said pulse generator to said heart;

means for sensing arterial blood pressure and generating a signal indicative of arterial blood pressure; and

means for generating said rate input signal in response to said signal indicative of arterial blood pressure.

2. A cardiac pacemaker as defined in claim 1, wherein said pulse generator generates said periodic electrical pulses only in the absence of naturally occurring heartbeats.

3. A cardiac pacemaker as defined in claim 1, wherein said sensing means senses arterial blood pressure at the proximal axillary artery.

4. A cardiac pacemaker as defined in claim 2, wherein said sensing means is located externally of the proximal axillary artery.

5. A cardiac pacemaker as defined in claim 1, wherein said sensing means comprises:

a transducer located externally about an artery for producing a variable output indicative of the stretch in the arterial wall caused by pressure change of blood within said artery.

6. A cardiac pacemaker as defined in claim 5, wherein said transducer is a strain detector device.

7. A cardiac pacemaker as defined in claim 5, wherein said transducer operates by measuring pulse transit time.

8. A cardiac pacemaker as defined in claim 1, wherein said generating means has as an input the signal generated by said sensing means, said generating means using a transfer function to produce said rate input signal in response to said signal generated by said sensing means.

9. A cardiac pacemaker as defined in claim 8, wherein said transfer function is nonlinear.

10. A cardiac pacemaker as defined in claim 8, wherein said transfer function is linear.

11. A cardiac pacemaker as defined in claim 10, wherein said rate input signal is commanded heart interval, and said transfer function produces a value of commanded heart interval which is equal to a first constant a times the signal indicative of arterial pressure, plus a second constant b.

12. A cardiac pacemaker as defined in claim 10, wherein said rate input signal is commanded heart rate, and said transfer function produces a value of commanded heart rate which is equal to a third constant c times the signal indicative of arterial pressure, plus a fourth constant d.

13. A cardiac pacemaker as defined in claim 1, wherein said generating means comprises:

means for amplifying the signal indicative of arterial blood pressure, said amplifying means having a gain a and producing an amplified output; and

means for summing said amplified output with a constant b to produce said rate input signal.

14. A cardiac pacemaker as defined in claim 13, additionally comprising:

means for maintaining the long term resting heart rate at a predetermined rate.

15. A cardiac pacemaker as defined in claim 14, wherein said maintaining means comprises:

means for generating an error signal between said predetermined rate and said rate input signal; and

means for periodically resetting said constant b in response to said error signal.

16. A cardiac pacemaker as defined in claim 13, additionally comprising:

means for filtering said signal indicative of blood pressure to minimize harmonics due to the pulsatile nature of the arterial pressure waveform.

17. A cardiac pacemaker as defined in claim 16, wherein said filtering means has a time constant of between 0.3 and 1.6 seconds.

18. A cardiac pacemaker as defined in claim 1, wherein said generating means produces a rate input signal corresponding to a heart rate of between 60 and 170 beats per minute.

19. A cardiac pacemaker as defined in claim 1, additionally comprising:

means for maintaining the long term resting heart rate at a predetermined level.

20. A cardiac pacemaker for stimulating a heart to beat at a rate which is variable in response to physiological need, comprising:

a pulse generator for generating periodic electrical pulses at a rate determined by a rate input signal supplied to said pulse generator;

a pacing lead for delivering said periodic electrical pulse generated by said pulse generator to said heart;

a transducer located about an artery for producing a variable output signal indicative of arterial blood pressure in response to the stretch in the arterial wall caused by pressure change of blood within said artery;

means for amplifying the signal indicative of arterial blood pressure, said amplifying means having a gain a and producing an amplified output; and

means for summing said amplified output with a constant b to produce said rate input signal.

21. A cardiac pacemaker for stimulating a heart to beat at a rate which is variable in response to physiological need, comprising:

a pulse generator for generating periodic electrical pulses at a rate determined by a rate input signal supplied to said pulse generator;

a pacing lead for delivering said periodic electrical pulse generated by said pulse generator to said heart;

a transducer located about an artery for producing a variable output signal indicative of arterial blood pressure in response to the stretch in the arterial wall caused by pressure change of blood within said artery;

means for amplifying the signal indicative of arterial blood pressure, said amplifying means having a gain a and producing an amplified output;

means for summing said amplified output with a constant b to produce said rate input signal; and

means for maintaining the long term resting heart rate at a predetermined rate.

22. A method of stimulating a heart to beat at a rate which is variable in response to physiological need, comprising:

sensing arterial blood pressure and generating a signal indicative of arterial blood pressure;

generating said rate input signal in response to said signal indicative of arterial blood pressure;

generating periodic electrical pulses at a rate determined by a rate input signal; and

delivering said periodically generated electrical pulse to said heart.