Systems and methods for automated charge balancing of multiple electrodes for uninterrupted therapy and evoked response sensing

Patent metadata

Field	Value
Publication number	US-10183168-B2
Application number	US-201715451838-A
Country	US
Kind code	B2
Filing date	Mar 7, 2017
Priority date	Mar 10, 2016
Publication date	Jan 22, 2019
Grant date	Jan 22, 2019

Abstract

Electrical stimulation of a target (e.g., nervous tissue) is performed, wherein balance phases are automatically determined, and at least one of the electrodes is indirectly monitored during therapy delivery. The stimulation system is further configured to generate correction currents when a voltage accumulated at associated double layer capacitances crosses pre-defined thresholds so as to reduce or cancel the accumulated voltages without therapy interruption. A finer automatic determination of balance phases permits minimizing the stimulus artifact for evoked response sensing. Closed-loop neurostimulation may be performed based on such evoked responses.

First claim

What is claimed is:

1. A method for automatic charge balancing during delivery of electrical stimulation to tissue using a pulse generator ( 700 ), the pulse generator ( 700 ) having:
I. a stimulating electrode (W, X),
II. a return electrode (Y), and
III. a forced return electrode (Z),
wherein:
A. the stimulating electrode (W, X), the return electrode (Y), and the forced return electrode (Z) are configured to deliver the electrical stimulation,
B. each electrode (W, X, Y, Z) is coupled by a respective DC-blocking capacitor (C i ) to a current source (S), a current sink (S′), or a voltage, and
C. each electrode (W, X, Y, Z) defines a capacitance (C dli ) when forming a double layer with adjacent tissue,
the method including the steps of:
a. in a determination stage, programming stimulation current pulses (I Ni ) and determining balancing current pulses (I Pi ) for each electrode (i=W, X, Y, Z) wherein:
(1) for the stimulating electrode (W, X), the difference between the stimulation current pulse (I Ni ) and balancing current pulse (I Pi ) is a positive value;
(2) for each of the return electrode (Y) and the forced return electrode (Z), the difference between the stimulation current pulse (I Ni ) and the balancing current pulse (I Pi ) is:
(a) positive, and
(b) less than or equal to the difference between the stimulation current pulse (I Ni ) and balancing current pulse (I Pi ) for the stimulating electrode (W, X);

b. in a stimulation stage following the determination stage:
(1) repeatedly applying stimulation cycles via the stimulating electrode (i=W, X) and the return electrode, each stimulation cycle including:
(a) the stimulation current pulse (I Ni );
(b) the balancing current pulse (I Pi ) following the stimulation current pulse (I Ni );
(c) an open circuit phase (OCP) following the balancing current pulse (I Pi ), wherein no current is applied via the stimulating electrode (W, X);

(2) monitoring at least one of the electrodes (W, X, Y, Z); and
(3) generating correction currents (I CORRStim , I CORRRet ) when an accumulated voltage (ΔV dli ) at the double layer of any of the monitored electrodes crosses pre-defined thresholds (−ΔV AddOCP , ΔV SubOCP ), wherein the correction currents (I CORRStim , I CORRRet ) reduce the accumulated voltage (ΔV dli ).

2. The method of claim 1 wherein any crossing of the pre-defined thresholds (−ΔV AddOCP , ΔV SubOCP ) by the accumulated voltage (ΔV dli ) of one of the monitored electrodes is detected by comparing:
a. a voltage on a terminal of the DC-blocking capacitor CO opposite the monitored electrode, and
b. the difference between:
(1) a voltage reference, and
(2) an estimated accumulated voltage (P*ΔV CStim | Per Pulse , P*ΔV CRet | Per Pulse , or P*ΔV CFor | Per Pulse ) at the DC blocking capacitor (C i ) of the monitored electrode.

3. The method of claim 2 wherein the stimulation current pulse (I Ni ) and/or the balancing current pulse (I Pi ) are determined in dependence on:
a. patient posture, and/or
b. stimulation cycle frequency.

4. The method of claim 3 wherein the determination stage includes providing stimulation current pulses (I Ni ) from each electrode (i=W, X, Y, Z) to a reference electrode ( 201 ).

5. The method of claim 4 wherein the reference electrode ( 201 ) is defined by a casing ( 201 ) of the pulse generator ( 700 ).

6. The method of claim 1 wherein the stimulation current pulse (I Ni ) and/or the balancing current pulse (I Pi ) are determined such that any stimulus artifact (SA) resulting from a stimulation cycle is minimized.

7. The method of claim 6 further including the step of sensing evoked compound action potentials (ECAPs), each evoked compound action potential resulting from one of the stimulation cycles.

8. The method of claim 7 wherein evoked compound action potentials (ECAPs) are sensed using at least one of:
a. adaptive frequencies, and/or
b. equivalent-time sampling techniques.

9. The method of claim 7 wherein evoked compound action potentials (ECAPs) are sensed using three recording electrodes (B 6 , B 7 , B 8 ).

10. The method of claim 9 wherein:
a. the recording electrodes (B 6 , B 7 , B 8 ) are provided on at least one implantable lead connected to the pulse generator ( 700 ), and
b. the recording electrodes (B 6 , B 7 , B 8 ) are provided in:
(1) a tripolar arrangement, or
(2) a quasi-tripolar arrangement.

11. The method of claim 9 wherein:
a. the pulse generator ( 700 ) includes first and second leads ( 701 . a , 701 . b );
b. one of the leads ( 701 . a , 701 . b ) has the stimulating electrode (A 3 , B 2 ) and return electrode (A 2 , A 4 , B 1 , B 3 ) thereon, with the stimulating electrode being guarded by the return electrode; and
c. one of the leads ( 701 . a , 701 . b ) has the recording electrodes (B 6 , B 7 , B 8 ) thereon.

12. The method of claim 11 wherein:
a. the stimulating electrode (A 3 , B 2 ) is situated closer to a proximal end of one of the leads than the recording electrodes (B 6 , B 7 B 8 ), and the recording electrodes (B 6 , B 7 , B 8 ) are situated closer to a distal end of one of the leads than the stimulating electrode (A 1 , B 2 ); or
b. the stimulating electrode (A 3 , B 2 ) is situated closer to a distal end of one of the leads than the recording electrodes (B 6 , B 7 , B 8 ) and the recording electrodes (B 6 , B 7 , B 8 ) are situated closer to a proximal end of one of the leads than the stimulating electrode (A 3 , B 2 ).

13. The method of claim 11 further including the step of detecting changes in relative positioning of the leads ( 701 . a , 701 . b ), the step including determining latency value changes of ECAPs.

14. The method of claim 1 wherein each electrode (W, X, Y, Z) is coupled to its respective current source (S), current sink (S′), or voltage solely via its respective DC-blocking capacitor (Ci).

15. The method of claim 1 wherein in the determination stage, the stimulation current pulses (I Ni ) are programmed, and the balancing current pulses (I Pi ) are determined, such that:
a. the DC blocking capacitor (C i ) and defined capacitance (C dli ) of each electrode (W, X, Y, Z) charge in the same direction; and
b. the DC-blocking capacitor (C i ) and defined capacitance (C dli ) of the stimulating electrode (W, X) charge in directions opposite the charging of the DC-blocking capacitor (C i ) and defined capacitance (C dli ) of the return and forced return electrode (Y, Z).

16. A method for automatic charge balancing during delivery of electrical stimulation to tissue using a pulse generator ( 700 ), the pulse generator ( 700 ) having:
I. a stimulating electrode (W, X),
II. a return electrode (Y), and
III. a forced return electrode (Z),
wherein:
A. the stimulating electrode (W, X), the return electrode (Y), and the forced return electrode (Z) are configured to deliver the electrical stimulation,
B. each electrode (W, X, Y, Z) is coupled by a respective DC-blocking capacitor (C i ) to a current source (S), a current sink (S′), or a voltage, and
C. each electrode (W, X, Y, Z) defines a capacitance (C dli ) when forming a double layer with adjacent tissue,
the method including the steps of:
a. in a determination stage, programming stimulation current pulses (I Ni ) and determining balancing current pulses (I Pi ) for each electrode (i=W, X, Y, Z) wherein:
(1) the DC-blocking capacitor (C i ) and defined capacitance (C dli ) of each electrode (W, X, Y, Z) charge in the same direction;
(2) the DC-blocking capacitor (C i ) and defined capacitance (C dli ) of the stimulating electrode (W

Assignees

• Biotronik Se & Co Kg

Inventors

• Baru Marcelo
• Vijayagopal Ramprasad

Classifications

• A61N1/36139

  with automatic adjustment · CPC title

• A61N1/36125

  Details of circuitry or electric components · CPC title

• A61N1/0551

  Spinal or peripheral nerve electrodes · CPC title

• A61N1/36153 Primary

  Voltage (A61N1/3616 takes precedence) · CPC title

• A61N1/36178 Primary

  Burst or pulse train parameters · CPC title