System for and method of therapeutic stimulation of a patient's heart

• US 4,899,751 A
• Filed: 07/12/1989
• Issued: 02/13/1990
• Est. Priority Date: 10/06/1987
• Status: Expired due to Term

• Current Assignee: Medtronic Incorporated (Medtronic Plc)
• Original Assignee: Leonard Bloom
• Inventors: Cohen, Todd
• Primary Examiner(s): Jaworski, Francis
• Assistant Examiner(s): Manuel, George
• Application Number:
  US07/378,708
• Time in Patent Office: 216 Days
• Field of Search: 128/419 PG, 128/672, 128/419 P, 128/673
• US Class Current: 607/23
• CPC Class Codes: A61N 1/36564 controlled by blood pressure
• CPC Class Codes: A61N 1/3918 characterised by shock pathway, e.g. by electrode configuration

Abstract

A system for therapeutic stimulation of a patient'"'"'s heart includes means for varying the escape interval or rate of a means for producing pacing pulses. Pressure sensing means sense pressure at a site in the circulatory system of a patient. Signal producing means respond to output from the sensing means to develop a variable first signal representative of mean pressure at the site over a period of predetermined duration. Signal producing means respond to output from the sensing means for developing a second signal representing mean pressure at the site over a period of given duration less than the period of predetermined duration. Control signal producing means responsive to the first signal and to the second signal develop a control signal upon the first signal and the second signal differing by at least a predetermined amount. Control means, responsive to the control signal, control the means for varying the escape interval or rate of the means for producing pacing pulses. The escape interval or rate may be additionally controlled by a second control signal related to the activity level of the patient either conjointly or contemporaneously. A method of therapeutic stimulation of a patient'"'"'s heart is also disclosed. The method can be viewed as an analogue of the system.

Claims

1. In a system for therapeutic stimulation of a patient'"'"'s heart and which includes means for varying escape interval or rate of a means for producing pacing pulses, an improvement comprising means for sensing pressure®

at a site in circulatory system of a patient, means responsive to output from the sensing means for developing a variable first signal representative of mean pressure at the site over a period of predetermined duration, means responsive to output from the sensing means for developing a second variable signal representative of mean pressure at the site over a period of given duration less than the period of predetermined duration, means responsive to the first variable signal and to the second variable signal for developing a first control signal whenever the first variable signal and the second variable signal differ by at least a predetermined amount, means responsive to a signal dependent on at least one physiological variable for developing a second control signal, and means for alternatively supplying the first control signal and the second control signal to the means for varying the escape interval or rate of the means for producing pacing pulses, the second control signal being supplied in absence of the first control signal and the first control signal being supplied, when present, to exclusion of the second control signal.

2. The system of claim 1 wherein said means responsive to a signal dependent on at least one physiological variable for developing a second control signal comprises means for sensing activity level of a patient as the physiological variable and means responsive to output from the means for sensing activity level to develop the second control signal.

3. The system of claim 1, wherein said means for sensing pressure at a site in a circulatory system comprises means for sensing right atrial pressure.

4. The system of claim 1, wherein said means for sensing pressure at a site in a circulatory system comprises means for sensing right ventricular pressure.

5. The system of claim 1, wherein said means for sensing pressure at a site in a circulatory system comprises means for sensing central venous pressure.

6. The system of claim 1, wherein said means for sensing pressure at a site in a circulatory system comprises means for sensing left atrial pressure.

7. The system of claim 1, wherein said means for sensing pressure at a site in a circulatory system comprises means for sensing left ventricular pressure.

8. The system of claim 1, wherein said means for sensing pressure at a site in a circulatory system comprises means for sensing arterial pressure.

9. The system of claim 1, wherein said developing mens includes a microprocessor means for developing the said first and second control signals.

10. A method of therapeutic stimulation of a patient'"'"'s heart comprising:

sensing mean pressure at a site in circulatory system of said patient during a current period and a baseline period of respective given duration;

comparing mean pressure at the site as determined over said baseline period of given duration with mean pressure at the site as determined over said current period of given duration, said current period of given duration being less than the duration of the baseline of given duration, to find if the determined means pressures at the site differ by at least a predetermined amount;

sensing at least one physiological variable of the patient; and

controlling escape interval or rate of a pacing system alternatively based on the at least one physiological variable whenever the determined mean pressures at the site differ by less than the predetermined amount and based, on pressure at the site whenever the mean pressures differ by at least the predetermined amount.

11. The method according to claim 10, wherein the step of sensing at least one physiological variable comprises sensing vibrational energy at a site in or on the patient and converting the sensed energy into an activity related signal.

12. The method of claim 10, wherein the step of sensing pressure comprises sensing right atrial pressure.

13. The method of claim 10, wherein the step of sensing pressure comprises sensing right ventricular pressure.

14. The method of claim 10, wherein the step of sensing pressure comprises sensing central venous pressure.

15. The method of claim 10, wherein the step of sensing pressure comprises sensing left atrial pressure.

16. The method of claim 10, wherein the step of sensing pressure comprises sensing left ventricular pressure.

17. The method of claim 10, wherein the step of sensing pressure comprises sensing arterial pressure.

18. In a system for therapeutic stimulation of a patient'"'"'s heart and which includes means for varying escape interval or rate of a means for producing pacing pulses, an improvement comprising means for sensing pressure at a site in circulatory system of a patient, means responsive to output from the sensing means for developing a variable first signal representative of mean pressure at the site over a period of predetermined duration, means responsive to output from the sensing means for developing a variable second signal representative of mean pressure at the site over a period of given duration less than the period of predetermined duration, means responsive to the first variable signal and to the second variable signal for developing a stored first signal upon the first variable signal and the second variable signal differing by at least a predetermined amount, means responsive to the stored first variable signal and to the second variable signal for developing a first control signal whenever the first variable signal and the second variable signal differ by at least a given amount, means responsive to a signal dependent on at least one physiological variable for developing a second control signal, and means for alternatively supplying the first control signal and the second control signal to the means for varying the escape interval or rate of the means for producing pacing pulses, the second control signal being supplied in absence of the first control signal and the first control signal being supplied, when present, to exclusion of the second control signal, whereby the escape interval or rate may be determined alternatively by the at least one physiological variable and the hemodynamic pressure at a site in said circulatory system.

19. The system according to claim 18, wherein the predetermined amount is greater than the given amount.

20. A method of therapeutic stimulation of a patient'"'"'s heart comprising:

sensing pressure at a site in circulatory system of a patient;

comparing means pressure at the site as determined over a period of predetermined duration with mean pressure at the site as determined over a current period of given duration less than the duration of the period of predetermined duration to find if the determined mean pressures at the site differ by at least a predetermined amount;

storing a representation of the mean sensed pressure at the site as determined over a period of predetermined duration at the time the sensed means pressure differed by at least the predetermined amount;

comparing the stored representation of the sensed mean pressure with mean sensed pressure at the site as determined over a current period of the given duration to determine if current mean pressure at the site differs from the stored representation by at least a given amount;

sensing at least one physiological variable of the patient; and

controlling escape interval or rate of a pacing system alternatively based on said at least one physiological variable upon determine that mean pressures at the site differ by less than the given amount and based upon current mean pressure at the site differing from the stored representation of the mean pressure by at least the given amount.