Method and device for responding to the detection of ischemia in cardiac tissue

• US 20020072777A1
• Filed: 12/08/2000
• Published: 06/13/2002
• Est. Priority Date: 12/08/2000
• Status: Active Grant

• Current Assignee: Pacesetter Incorporated (Abbott Laboratories Incorporated)
• Original Assignee: Pacesetter Incorporated (Abbott Laboratories Incorporated)
• Inventors: Lu, Richard
• Granted Patent: US 6,604,000 B2
• Time in Patent Office: Days
• US Class Current: 607/17
• CPC Class Codes: A61N 1/36514 controlled by a physiological quantity other than heart potential, e.g. blood pressure controlled by two or more physical parameters A61N1/36585

Abstract

An apparatus and method for monitoring the patient'"'"'s heart for the presence of ischemia and altering the treatment delivered by an implantable cardiac stimulation device to minimize adverse ischemic effects, e.g., angina pectoris. Embodiments of the present invention are particularly beneficial when used with a rate responsive cardiac stimulation device. Typically, a rate responsive cardiac stimulation device increases its pacing rate (up to a maximum sensor rate) in response to increases in the patient'"'"'s activity level. The rate of this change is referred to in this patent as the aggressiveness of the rate responsiveness. However, in an ischemic state, the aggressiveness of the rate responsiveness may cause the heart to pace at a rate that exacerbates the ischemic effects. Accordingly, embodiments of the present invention alter the pacing regimen in one or more of the following ways. First, the maximum sensor rate is adaptively decremented in response to a detected ischemic state. Second, the aggressiveness of the rate responsiveness is adaptively decreased in response to a detected ischemic state. Third, the atrio-ventricular delay (AV) delay is adaptively extended in response to a detected ischemic state. Conversely, when an ischemic state is no longer detected, the adapted variable is incrementally returned toward its original value. Accordingly, ischemia can be minimized while still maintaining the rate responsive features of the implantable cardiac stimulation device.

Claims

1. A method of treating ischemia of a patient'"'"'s heart using an implantable cardiac stimulation device operating according to a set of prescribed adaptable pacing parameters including a pacing rate set as a function of the patient'"'"'s activity level up to a maximum sensor rate and an aggressiveness value specifying the rate of increase of the pacing rate per the increase in the patient'"'"'s activity level, wherein each of the parameters has an original value in the absence of ischemia, the method comprising the steps of:

detecting the presence of ischemia in the patient'"'"'s heart; and

incrementally altering at least one of the prescribed adaptable pacing parameters of the cardiac stimulation device by a specified amount, initially from its respective original value, in response to detecting the presence of ischemia in the patient'"'"'s heart.

2. The method of claim 1 wherein the step of incrementally altering at least one of the prescribed adaptable pacing parameters additionally comprises the step of continuing to periodically incrementally alter at least one of the prescribed adaptable pacing parameters by the specified amount while ischemia is still detected.

3. The method of claim 2 wherein the step of periodically incrementally altering at least one of the prescribed adaptable pacing parameters is only performed within a defined range of increments.

4. The method of claim 1 wherein the step of incrementally altering at least one of the prescribed adaptable pacing parameters comprises incrementally decreasing the maximum sensor rate.

5. The method of claim 1 wherein the step of incrementally altering at least one of the prescribed adaptable pacing parameters comprises incrementally decreasing the rate response aggressiveness.

6. The method of claim 5 wherein the rate of increase of the pacing rate per the increase in the patient'"'"'s activity level is defined in at least two activity level ranges and decreasing the rate response aggressiveness value in response to the presence of ischemia specifies decreasing the rate of increase in at least one of the defined activity level ranges.

7. The method of claim 1 wherein the step of incrementally altering at least one of the prescribed adaptable pacing parameters comprises incrementally decreasing the maximum sensor rate and incrementally decreasing the rate response aggressiveness.

8. The method of claim 1 additionally comprising the step of incrementally altering at least one of the prescribed adaptable pacing parameters of the cardiac stimulation device back toward its original value in response to not detecting the presence of ischemia in the patient'"'"'s heart for a prescribed time period.

9. The method of claim 1 wherein the prescribed adaptable pacing parameters additionally include AV/PV delay values defining the delay between an atrial event and delivery of a ventricular stimulation pulse by the cardiac stimulation device and the incrementally altering step comprises increasing the AV/PV delay values by a specified amount in response to detecting the presence of ischemia in the patient'"'"'s heart.

10. The method of claim 9 additionally comprising the step of incrementally decreasing the AV/PV delay values by a specified amount in response to not detecting the presence of ischemia in the patient'"'"'s heart for a prescribed period of time.

11. The method of claim 9 wherein the step of incrementally altering at least one of the prescribed adaptable pacing parameters comprises incrementally decreasing the maximum sensor rate, incrementally decreasing the rate response aggressiveness, and incrementally increasing the AV/PV delay values.

13. The cardiac stimulation device of claim 12 wherein the controller additionally alters at least one of the prescribed adaptable pacing parameters of the cardiac stimulation device in response to the ischemia detector not detecting the presence of ischemia for a prescribed period.

14. The cardiac stimulation device of claim 12 wherein the at least one electrode includes an electrode in electrical contact with an atrium of the patient'"'"'s heart and an electrode in electrical contact with a ventricle of the patient'"'"'s heart and the at least one pulse generator includes an atrial pulse generator and a ventricular pulse generator to respectively generate atrial and ventricular stimulation pulses to the atrium and ventricle of the patient'"'"'s heart;

and wherein

the prescribed adaptable pacing parameters include an AV delay defining the delay between delivery of an atrial stimulation pulse and delivery of a ventricular stimulation pulse by the cardiac stimulation device and the controller increases the AV delay by a prescribed amount in response to the ischemia detector detecting the presence of ischemia.

15. The cardiac stimulation device of claim 14 wherein the controller decreases the increased AV delay in response to the ischemia detector not detecting the presence of ischemia for a prescribed period of time.

16. The cardiac stimulation device of claim 12 wherein the at least one electrode includes an electrode in electrical contact with an atrium of the patient'"'"'s heart and an electrode in electrical contact with a ventricle of the patient'"'"'s heart and the at least one pulse generator is configured to deliver ventricular stimulation pulses to the ventricle of the patient'"'"'s heart, the cardiac stimulation device additional comprising:

a sensing circuit configured to receive a signal from the electrode in electrical contact with the atrium of the patient'"'"'s heart for detecting intrinsic P-waves from the patient'"'"'s heart; and

wherein

the pacing parameters additionally include a PV delay defining the delay between a sensed P-wave and delivery of a ventricular stimulation pulse by the cardiac stimulation device and the controller increases the PV delay by a specified amount in response to the ischemia detector detecting the presence of ischemia.

17. The cardiac stimulation device of claim 16 wherein the controller decreases the increased PV delay in response to the ischemia detector not detecting the presence of ischemia for a prescribed period of time.

18. The cardiac stimulation device of claim 12 wherein the controller continues to periodically incrementally alter at least one of the prescribed adaptable pacing parameters by the specified amount while ischemia is still detected by the ischemia detector.

19. The cardiac stimulation device of claim 12 wherein the controller increment ally alters at least one of the prescribed adaptable pacing parameters only within a defined range of increments.

20. The cardiac stimulation device of claim 12, additionally comprising:

an activity sensor for determining the patient'"'"'s activity level;

a controller, coupled to the pulse generator and the activity sensor for determining the pacing rate as a function of the determined patient'"'"'s activity level up to a maximum sensor rate and according to a rate response aggressiveness value specifying the rate of increase of the pacing rate per the increase in the patient'"'"'s activity level, wherein the prescribed adaptable pacing parameters include the maximum sensor rate and the rate response aggressiveness values; and

wherein

the controller is configured to incrementally alter at least one of the prescribed adaptable pacing parameters of the cardiac stimulation device by a specified amount from its respective original value in response to detecting the presence of ischemia by the ischemia detector.

21. The cardiac stimulation device of claim 20 wherein the controller incrementally decreases the maximum sensor rate in response to ischemia being detected by the ischemia detector.

22. The cardiac stimulation device of claim 20 wherein the controller incrementally decreases the rate response aggressiveness in response to ischemia being detected by the ischemia detector.

23. The cardiac stimulation device of claim 22 wherein the rate of increase of the pacing rate per the increase in the patient'"'"'s activity level is defined in at least two activity level ranges and the controller decreases the rate response aggressiveness in response to ischemia being detected by the ischemia detector by decreasing the rate of increase in at least one of the defined activity level ranges.

24. The cardiac stimulation device of claim 20 wherein the controller incrementally decreases the maximum sensor rate and incrementally decreases the rate response aggressiveness in response to ischemia being detected by the ischemia detector.

25. The cardiac stimulation device of claim 20 wherein the controller incrementally alters at least one of the prescribed adaptable pacing parameters of the cardiac stimulation device back toward its original value in response to not detecting the presence of ischemia by the ischemia detector for a prescribed time period.

26. The cardiac stimulation device of claim 20 wherein the prescribed adaptable pacing parameters additionally include AV/PV delay values defining the delay between an atrial event and delivery of a ventricular stimulation pulse by the cardiac stimulation device and the controller incrementally increases the AV/PV delay values by a specified amount in response to detecting the presence of ischemia by the ischemia detector.

27. The cardiac stimulation device of claim 26 wherein the controller incrementally decreases the AV/PV delay values by a specified amount in response to not detecting the presence of ischemia by the ischemia detector for a prescribed period of time.

28. The cardiac stimulation device of claim 20 wherein the controller incrementally decreases the maximum sensor rate, incrementally decreases the rate response aggressiveness, and incrementally increases the AV/PV delay values in response to detecting the presence of ischemia by the ischemia detector.

30. The device of claim 29 wherein at least one of the prescribed adaptable pacing parameters is incrementally altered to minimize the presence of ischemia in response to detecting the presence of ischemia by the ischemia detecting means.

31. The device of claim 30 wherein the altered pacing parameter is incrementally altered back toward its original value in response to not detecting the presence of ischemia by the ischemia detecting means for a prescribed period of time.

12. An implantable cardiac stimulation device configured for stimulating a patient'"'"'s heart through at least one electrode implanted in electrical contact with selected cardiac tissue, the cardiac stimulation device comprising:

at least one pulse generator configured for electrical coupling to the at least one electrode and configured to generate stimulation pulses at a pacing rate according to a set of prescribed adaptable pacing parameters, wherein each parameter has an original value in the absence of ischemia;

an ischemia detector configured for determining the presence of ischemia in at least a portion of the cardiac tissue;

a controller, coupled to the ischemia detector for periodically altering at least one of the prescribed adaptable pacing parameters of the cardiac stimulation device by a specified incremental amount, initially from its respective original value, in response to detecting the presence of ischemia by the ischemia detector.

29. An implantable cardiac stimulation device configured for stimulating a patient'"'"'s heart through at least one electrode implanted in electrical contact with selected cardiac tissue, the cardiac stimulation device comprising:

means for generating and delivering stimulation pulses to the at least one electrode according to a set of prescribed adaptable pacing parameters, wherein each pacing parameter has an original value in the absence of ischemia;

means for detecting the presence of ischemia in at least a portion of the cardiac tissue; and

means for periodically altering at least one of the prescribed adaptable pacing parameters of the cardiac stimulation device by a specified incremental amount, from its respective original value, in response to detecting the presence of ischemia by the ischemia detecting means.

32. A method of treating ischemia of a patient'"'"'s heart using an implantable cardiac stimulation device operating according to a set of one or more prescribed adaptable pacing parameters including at least a pacing rate set as a function of the patient'"'"'s activity level up to a maximum sensor rate, wherein each of the parameters has an original value in the absence of ischemia, the method comprising the steps of:

detecting the presence of ischemia in the patient'"'"'s heart;

determining the pacing rate when ischemia is detected;

altering the maximum sensor rate according to the pacing rate when ischemia is detected;

incrementally altering at least one of the prescribed adaptable pacing parameters of the cardiac stimulation device by a specified amount in response to continuing to detect the presence of ischemia in the patient'"'"'s heart.