Antidromic pulse generating wave form for collision blocking

• US 4,608,985 A
• Filed: 10/11/1984
• Issued: 09/02/1986
• Est. Priority Date: 10/11/1984
• Status: Expired due to Term

• Current Assignee: Case Western Reserve University
• Original Assignee: Case Western Reserve University
• Inventors: Mortimer, J. Thomas, Sweeney, James D., Crish, Timothy J.
• Primary Examiner(s): Kamm, William E.
• Assistant Examiner(s): Shein, Mitchell J.
• Application Number:
  US06/659,825
• Time in Patent Office: 691 Days
• Field of Search: 128/419 R, 128/419 C, 128/642, 128/784-785, 128/802, 128/421-423
• US Class Current: 607/74
• CPC Class Codes: A61N 1/0556 Cuff electrodes
• CPC Class Codes: A61N 1/36146 specified by the stimulation parameters

Abstract

An electrode cuff (B) including a dielectric sleeve (10) and an annular cathode electrode (20) is disposed around a nerve trunk (A). An anode electrode (22) is disposed in body fluids in electrical communication with the nerve trunk. The cathode electrode is disposed off center within the dielectric sleeve. The flow of electric current from the anode to the cathode has a much greater amplitude along the nerve in the direction extending along the nerve trunk toward the cathode from the end of the dielectric sleeve toward which the cathode electrode is closest. A signal generator (C) applies a pulse train across the anode and cathode electrodes. The pulse train includes a plurality of alternating first amplitude pulse portions (40) and opposite polarity pulse portions (42). Each first polarity pulse includes a sharp leading edge (50) which rises abruptly to a preset amplitude (52). A trailing edge (56) of each first pulse portion decays smoothly into a leading edge (60) of each opposite polarity pulse portion without a discontinuity therebetween. The opposite polarity pulse portion has an amplitude (62) which is smaller than the triggering amplitude and a duration which is longer than the first polarity pulse portion duration. The amplitude and duration of the first and opposite polarity pulse portions are selected such that the net charge transfer in each direction is substantially the same.

Claims

1. A method of generating an antidromic action potential traveling unidirectionally along a nerve trunk while maintaining a balanced net charge transfer therealong, the method comprising:

applying an electrical waveform including a first current pulse portion of a first polarity and a second current pulse portion of a second polarity to the nerve trunk, the first current pulse portion including;

a rapid amplitude increasing portion,

a relatively stable amplitude plateau portion, and

a discontinuity free decreasing portion;

the second pulse portion including;

an opposite polarity increasing portion which follows the first pulse portion with a smoothly and transition-free interface therebetween, the opposite polarity pulse portion having a relatively small amplitude as compared to the first pulse portion and a relatively long duration as compared to the first pulse portion;

the first pulse portion decreasing portion and the second polarity increasing portion taken together form a smooth, continuous waveform portion whose first derivative is smooth and continuous from the plateau portion through the interface to the opposite pulse relatively small amplitude.

2. The method as set forth in claim 1 wherein the charge transfer during the first pulse portion is substantially equal and opposite to the charge transfer during the second pulse portion.

3. The method as set forth in claim 2 wherein the second pulse portion includes a constant amplitude portion.

4. The method as set forth in claim 3 wherein the first polarity pulse portion increases rapidly to a trigger amplitude in the range of 1/2 to 20 milliamps.

5. The method as set forth in claim 3 wherein the first pulse portion plateau portion has a duration of 100 to 3000 microseconds.

6. The method as set forth in claim 3 wherein the first pulse portion plateau portion lasts about 1 to 10% of the cycle duration.

7. The method as set forth in claim 3 wherein the first pulse portion decreasing portion and the second pulse portion increase portion together have a duration in the range of 100 to 3000 microseconds.

8. The method as set forth in claim 3 wherein the first and second pulse portions are applied cyclically at a rate between 1 and 100 hertz.

9. An apparatus for causing the generation of antidromic action potentials, the apparatus comprising:

a cathode electrode dimensioned for substantially encircling a nerve trunk;

an anode electrode configured to be disposed in an electrically conductive relationship with the cathode electrode through the body fluids and the nerve trunk; and

,

a signal generator for cyclically generating a train of biphasic current pulses which includes alternating first polarity pulse portions and second, opposite polarity pulse portions, the first polarity pulse portions having a sharp leading edge and an amplitude great enough to trigger antidromic action potentials, each first pulse portion having a decaying trailing edge which diminishes smoothly and without discontinuities such that a first-derivative thereof increases smoothly and continuously, each second pulse portion having a leading edge which is smooth and continuous with the first pulse trailing edge without discontinuities at an interface therebetween such that the first derivative is smooth and continuous across the interface, each second pulse portion having an amplitude less than the trigger amplitude to avoid triggering action potentials in an opposite direction along the nerve trunk, the second pulse portion terminating generally at the first pulse portion leading edge of the next cycle.

10. The apparatus as set forth in claim 9 wherein the cathode electrode is an annular ring.

11. The apparatus as set forth in claim 9 wherein the cathode electrode is disposed in an interior bore of a dielectric sleeve, which dielectric sleeve is adapted to be disposed circumferentially around the nerve trunk.

12. The apparatus as set forth in claim 11 wherein the cathode electrode is disposed asymmetrically within the dielectric sleeve.

13. The apparatus as set forth in claim 12 wherein the anode electrode is adapted to be disposed in body fluids displaced from the dielectric sleeve.

14. The apparatus as set forth in claim 9 wherein the signal generator includes:

a primary pulse shaping circuit for generating a monophasic primary pulse which has a square wave portion and an exponential decay portion;

a reverse current clamping circuit for generating a monophasic reverse polarity phase; and

,

an output circuit for combining the primary and reverse polarity pulses and applying the current pulses across the cathode and anode.

15. The apparatus as set forth in claim 14 wherein the signal generator further includes a reverse current minimizing circuit for controlling the amplitude of the reverse polarity pulse such that the charge transfer during the second pulse portions substantially equals the charge transfer during the first pulse portions, the reverse current minimizing circuit being operatively connected with the output circuit for receiving a feedback portion of the biphasic pulses.

16. A method of generating an antidromic action potential traveling along a nerve trunk while maintaining a balanced net charged transfer therealong, the method comprising:

applying a first polarity rapidly increasing amplitude current to the nerve trunk, the current amplitude increasing sufficiently to trigger antidromic action potentials along the nerve trunk;

maintaining the applied current relatively stable at a first amplitude;

exponentially decreasing the applied current until current of an opposite polarity and a second amplitude is being applied, the exponential current decrease and the slope thereof being smooth and discontinuity-free such that the exponential decreasing current is free of sudden current amplitude changes which may trigger an action potential traveling along the nerve trunk, the second amplitude being smaller in magnitude than the first amplitude; and

,

continuing to apply current of the second polarity and generally the second amplitude until the net charge transfer along the nerve is balanced.

17. A method of generating an antidromic action potential traveling unidirectionally along a nerve trunk while maintaining a balanced net charge transfer therealong the method comprising:

cyclically applying an electrical waveform each cycle of which includes;

a rapid amplitude increasing portion,

a relatively stable first polarity plateau connected with the rapid amplitude increasing portion,

a relatively stable second polarity plateau, the second plateau having a relatively small magnitude and a relatively long duration as compared to the first polarity plateau, and

a smooth, discontinuity-free transition portion connected with the first and second polarity plateau, the slope of the transition portion being smooth and discontinuity-free between the first and second polarity plateaus.