System for stimulation therapy of the vagus nerve by implementation of a state transition model

1. A pacing therapy system, comprising:

a stimulation device;

one or more electrodes adapted to be placed on or near a nerve of an autonomic nervous system;

a sensor that senses at least one of a physiological signal or a physical signal;

a processing circuit that provides at least one of a current physiological level or a current physical level using the sensor; and

a control circuit that causes the stimulation device to provide stimulation according to a set of stimulation parameters, wherein the control circuit comprises:

a memory having a state transition model comprising a transition matrix and a connection matrix stored thereon, the transition matrix defining conditions for transitioning between particular states of a plurality of states of the state transition model and the connection matrix defining whether transitions between particular pairs of states are permitted, wherein the plurality of states are defined by a set of pacing parameter values and at least one of an expected physiological response or an expected physical response when applying stimulation with the set of stimulation parameters, wherein the state transition model is deterministic so the transition matrix is populated at an initialization of the system, and wherein the state transition model is based on a dichotomy between a plurality of minimum level states and a plurality of maximum level states; and

a state transition controller that determines transitions from a current state to a new state based on the state transition model, causing a corresponding change in the set of parameter values used for stimulation, from a current set of parameters associated with the current state to a new set of parameters associated with the new state.

2. The system of claim 1 , wherein the control circuit detects at least one of a physical abnormal state or a physiological abnormal state and transitions to a state of absence of stimulation in response to the detection.

3. The system of claim 1 , wherein the control circuit determines possible transitions between the plurality of states in a regular and predetermined method over time.

4. The system of claim 1 , wherein the control circuit determines possible transitions between the plurality of states in response to an occurrence of one or more predetermined events.

5. The system of claim 1 , wherein the state transition model is sequential, such that different states are ordered according to an effect they cause on a patient based on a transition from a state with a given pitch to at least one of a higher state of order, a lower state of order, or the same state of order.

6. The system of claim 5 , wherein the pitch is fixed.

7. The system of claim 5 , wherein the pitch is variable.

8. The system of claim 1 , wherein the control circuit determines a state containing a lowest response for which a difference between a measured physiological level and a target physiological level is below a given threshold.

9. The system of claim 1 , wherein the state transition model corresponds to a stochastic transition model with a plurality of cells, where each of the plurality of cells contain a probability value of transition from an initial state to a new state, and a sum of the probability values of a plurality of possible transitions from a given state to any new state are equal to 1.

10. The system of claim 9 , wherein the state transition model is a Hidden Markov Model.

11. The system of claim 9 , wherein the control circuit detects at least one of an abnormal physiological state or an abnormal physical state and transitions to a state of absence of stimulation in response to this detection.

12. The system of claim 1 , wherein the sensor detects at least one of: a cardiac, muscular or nervous electrogram signal; a body, cardiac or muscular, acceleration signal; a respiratory bioimpedance signal; a heart blood flow or heart blood pressure signal; a temperature signal; a piezometric pressure signal; or a cardiac contractility signal.

13. The system of claim 12 , wherein the at least one current physiological or physical level is determined from a variable corresponding to at least one of a heart rate, a sinus rhythm variability, a blood pressure, a cardiac contractility, a physical activity, a temperature, a movement, or a respiratory rate.

14. A method of applying a pacing therapy to a nerve of an autonomic nervous system with a stimulation device, the method comprising:

determining a state transition model comprising a plurality of states, wherein each state has a set of pacing parameter values and at least one of an expected physiological response or an expected physical response when applying stimulation with the set of stimulation parameters, wherein the state transition model is based on a dichotomy between a plurality of minimum level states and a plurality of maximum level states;

determining a transition matrix of the state transition model defining conditions for transitioning from a first state to a second state, wherein the state transition model is deterministic so the transition matrix is populated at an initialization of the device;

determining a connection matrix of the state transition model defining whether transitions between pairs of states are permitted;

determining transitions from a current state to a new state based on the state transition model, causing a corresponding change in the set of parameter values used for stimulation, from a current set of parameters associated with the current state to a new set of parameters associated with the new state.

15. The method of claim 14 , further comprising detecting at least one of a physical abnormal state or a physiological abnormal state and transitioning to a state of absence of stimulation in response to the detection.

16. The method of claim 14 , further comprising determining possible transitions between the plurality of states in a regular and predetermined method over time.

17. The method of claim 14 , further comprising determining possible transitions between the plurality of states in response to an occurrence of one or more predetermined events.

18. The method of claim 14 , wherein the state transition model is sequential, such that different states are ordered according to an effect they cause on a patient based on a transition from a state with a given pitch to at least one of a higher state of order, a lower state of order, or the same state of order.

19. A pacing therapy device comprising:

a stimulation device; and

a control circuit that causes a stimulation device to provide stimulation according to a set of stimulation parameters, wherein the control circuit comprises:

a memory having a state transition model comprising a transition matrix and a connection matrix stored thereon, the transition matrix defining conditions for transitioning between particular states of a plurality of states of the state transition model and the connection matrix defining whether transitions between particular pairs of states are permitted, wherein the plurality of states are defined by a set of pacing parameter values and at least one of an expected physiological response or an expected physical response when applying stimulation with the set of stimulation parameters, wherein the state transition model is deterministic so the transition matrix is populated at an initialization of the system, and wherein the state transition model is based on a dichotomy between a plurality of minimum level states and a plurality of maximum level states; and

a state transition controller that determines transitions from a current state to a new state based on the state transition model, causing a corresponding change in the set of parameter values used for stimulation, from a current set of parameters associated with the current state to a new set of parameters associated with the new state.