FLEXIBLE NEURAL STIMULATION ENGINE

• US 20070043398A1
• Filed: 10/19/2006
• Published: 02/22/2007
• Est. Priority Date: 04/28/2005
• Status: Active Grant

• Current Assignee: Cardiac Pacemakers Incorporated (Boston Scientific Corporation)
• Original Assignee: Cardiac Pacemakers Incorporated (Boston Scientific Corporation)
• Inventors: Ternes, David, Esler, James, Yost, David, Birkholz, Doug
• Granted Patent: US 7,751,884 B2
• Time in Patent Office: Days
• US Class Current: 607/18
• CPC Class Codes: A61N 1/025 Digital circuitry features of electrotherapy devices, e.g. memory, clocks, processors
• CPC Class Codes: A61N 1/36125 Details of circuitry or electric components
• CPC Class Codes: A61N 1/36135 using physiological parameters
• CPC Class Codes: A61N 1/362 Heart stimulators heart defibrillators A61N1/39
• CPC Class Codes: A61N 1/3682 with a variable atrioventricular delay

Abstract

An implantable medical device comprising stimulation circuitry adapted to provide neural stimulation energy to a neural stimulation electrode, one or more timers, including at least one neural event timer, a device behavior memory including a neural table, and a comparison circuit. The neural table maps a particular device state defined at least in part by a neural event timer to one or more associated device actions that include at least one of a neural stimulation energy delivery, a change in state of at least one neural event timer, and both a neural stimulation energy delivery and a change in state of one or more timers. The comparison circuit is adapted to compare a current state of one or more timers to a device state in the neural table and, if found to match, causing performance of one or more associated device actions.

Claims

1. An implantable medical device (IMD) comprising:

stimulation circuitry adapted to provide at least one neural stimulation energy to at least one neural stimulation electrode;

one or more timers, including at least one neural event timer, each timer having an output indicating a timer state and an input for changing the timer state;

a device behavior memory including a neural table, wherein the neural table maps a particular device state defined at least in part by a neural event timer to one or more associated device actions that include at least one of a neural stimulation energy delivery, a change in state of at least one neural event timer, and both a neural stimulation energy delivery and a change in state of one or more timers; and

a comparison circuit adapted to compare a current state of one or more timers to a device state in the neural table and, if found to match, causing performance of one or more associated device actions.

2. The IMD of claim 1, wherein the neural table includes:

one or more condition words representing respective device states, wherein a condition word represents a particular device state according to which bits of the condition word are set or cleared; and

one or more action words representing respective device actions that provide neural stimulation energy, wherein an action word represents a particular device action according to which bits of the action word are set or cleared.

3. The MD of claim 2, further including:

at least one implantable sensor adapted to produce an electrical sensor signal related to one or more physiologic events of a subject;

sensing circuitry coupled to the sensor, the sensing circuitry adapted to produce an indication of a sensed physiologic event in response to a result of a comparison of the electrical sensor signal to a specified threshold value; and

wherein the neural table maps at least one sensed physiologic event to a device state defined at least in part by the indication of the sensed physiologic event, and wherein the comparison circuit is adapted to compare the indication of the sensed physiologic event to a device state included in the neural table.

4. The IMD of claim 3, wherein the implantable sensor is selected from the group consisting of:

a) a heart sound sensor;

b) a blood pressure sensor;

c) a cardiac signal sensing circuit adapted to sense intracardiac electrograms;

d) a subcutaneous electrocardiograph (ECG) sensing circuit;

e) a cardiac wall motion sensor;

f) a transthoracic impedance sensor;

g) an intracardiac impedance sensor;

h) an accelerometer; and

i) a temperature sensor.

5. The IMD of claim 3, wherein a current state of the IMD is represented by a set of one or more timer outputs and a set of one or more comparison circuit outputs included in a current device status word, and wherein the condition words include a bit-by-bit correspondence to the current device status word.

6. The IMD of claim 5 including a state change detector and wherein one or more conditions words are sequentially compared with the current device status word when a bit of the current device status word changes as detected by the state change detector.

7. The IMD of claim 2, wherein a device action is represented by a set of one or more action inputs, wherein an action input includes at least one of a timer input and a neural stimulator input that causes delivery of neural stimulation energy to at least one neural stimulation electrode, and wherein the IMD further includes an action word in the neural table, wherein the action word includes a bit-by-bit correspondence to a set of one or more of the action inputs.

8. The IMD of claim 7, farther including a first-in first-out (FIFO) buffer queue coupled to the device behavior memory, and wherein at least one action input is adapted to cause an event represented in a current status word to be loaded into the FIFO buffer queue along with a time stamp.

9. The D of claim 1 further including

one or more brady event timers;

sensing circuitry, adapted to generate an indication of a sensed brady event in response to a result of a comparison of an electrogram signal amplitude to a specified threshold;

pacing circuitry adapted to deliver a pacing pulse to a pacing electrode;

a brady table included in the device behavior memory, wherein a combination of the brady table and the neural table is adapted to map one or more particular device states defined by one or more timer states or one or more indications of sensed events to respective device actions, wherein the device actions include any combination of bradycardia pacing energy delivery, neural stimulation energy delivery, or one or more changes in one or more timer states; and

wherein the comparison circuit is adapted to compare one or more current timer states or one or more indications of sensed brady events to a device state included in the combination of the brady table and neural table, and, if found to match causing performance of one or more associated device actions.

10. The IMD of claim 9, wherein the device behavior memory includes one or more action words representing respective device actions that include any combination of one or more of neural stimulation energy delivery or bradycardia pacing energy delivery, and wherein an action word represents a device action according to which one or more bits of the action word are set or cleared.

11. The IMD of claim 9 further including:

a processor, adapted to access the device behavior memory; and

a memory controller, enabled by the processor, the memory controller adapted to access the neural table and the brady table that are included in the device behavior memory.

12. A method for implementing a neural stimulation therapy mode in an implantable medical device (IMD), comprising the acts of:

mapping respective device states, defined by one or more timer states, including at least one neural event timer, or one or more indications of one or more sensed physiologic events, to associated device actions in a neural table, the device actions include neural stimulation energy delivery or changes in one or more timer states; and

comparing one or more current timer states or one or more indications of one or more sensed physiologic events to a device state contained in the neural table and, if found to match, causing performance of one or more associated device actions.

13. The method of claim 12, wherein mapping includes:

mapping respective device states to respective stored condition words, the condition words representing a particular device state according to which one or more bits of the word are set or cleared; and

mapping respective condition words to corresponding stored action words that represent corresponding device actions, wherein an action word represents a particular device action according to which one or more bits of the word are set or cleared.

14. The method of claim 13, wherein mapping particular IMD states includes mapping a device status word bit-by-bit to one or more condition words, and wherein the device status word includes a set of one or more timer outputs and a set of one or more sensing comparator outputs.

15. The method of claim 14, including:

detecting a change in device state by detecting a change in one or more bits of the device status word; and

sequentially comparing one or more condition words with a current device status word when the change in device state is detected.

16. The method of claim 15, including storing an action word in a FIFO queue along with a timestamp when a match is found between the condition word and the current device status word.

17. The method of claim 12, wherein mapping includes:

mapping one or more respective device states to associated device actions in a combined brady and neural table, the device actions include bradycardia energy therapy delivery or one or more changes in one or more timer states; and

comparing one or more current timer states or one or more indications of one or more sensed events to a device state included in the combined brady and neural table and, if found to match, causing performance of one or more associated device actions.

18. The method of claim 12, including sensing one or more physiologic events by detecting when an electrical sensor signal produced by at least one implantable sensor exceeds a specified threshold value, wherein the implantable sensor is selected from the group consisting of:

a) a heart sound sensor;

b) a blood pressure sensor;

c) a cardiac signal sensing circuit adapted to sense intracardiac electrograms;

d) a subcutaneous electrocardiograph (ECG) sensing circuit;

e) a cardiac wall motion sensor;

f) a transthoracic impedance sensor;

g) an intracardiac impedance sensor;

h) an accelerometer; and

i) a temperature sensor.

19. An implantable medical device (IMD) comprising:

stimulation circuitry adapted to provide at least one neural stimulation energy to at least one neural stimulation electrode;

one or more timers, including at least one neural event timer, each timer having an output indicating a timer state and an input for changing the timer state;

means for mapping respective device states, defined by one or more timer states or one or more sensed physiologic events, to associated device actions, wherein the device actions include neural stimulation energy delivery or one or more changes in one or more timer states that are included in a neural table; and

means for comparing one or more current timer states or one or more sensed physiologic events to a device state and, if found to match, causing performance of one or more associated device actions.

20. The IMD of claim 19, further including:

at least one implantable sensor adapted to produce an electrical sensor signal related to one or more physiologic events of a subject; and

sensing circuitry coupled to the sensor, the sensing circuitry adapted to produce the sensed physiologic events when the electrical sensor signal exceeds a specified threshold value.

21. The IMD of claim 19, further including means for queuing one or more device actions if a match is found between the current timer states or the sensed physiologic events and the device state.