Selective nerve fiber stimulation for treating heart conditions
View Patent ↗Apparatus for treating a heart condition of a subject is provided, including an electrode device, which is adapted to be coupled to a vagus nerve of the subject. A control unit is adapted to drive the electrode device to apply to the vagus nerve a stimulating current, which is capable of inducing action potentials in a therapeutic direction in a first set and a second set of nerve fibers of the vagus nerve. The control unit is also adapted to drive the electrode device to apply to the vagus nerve an inhibiting current, which is capable of inhibiting the induced action potentials traveling in the therapeutic direction in the second set of nerve fibers, the nerve fibers in the second set having generally larger diameters than the nerve fibers in the first set.
1. Apparatus for treating a condition of a subject, comprising:
an electrode device, configured to be coupled to a nerve of the subject;
a sensor configured to sense at least one feature of cardiac activity of the subject; and
a control unit, configured to:
drive the electrode device to apply to the nerve a stimulating current, which is configured to induce action potentials in (i) a first set of nerve fibers of the nerve, and (ii) a second set of nerve fibers of the nerve having generally larger diameters than the nerve fibers in the first set,
drive the electrode device to apply to the nerve an inhibiting current, which is configured to inhibit the induced action potentials in the second set of nerve fibers but not in the first set of fibers,
responsively to the at least one sensed feature of cardiac activity of the subject, configure at least one current selected from the group consisting of: the stimulating current, and the inhibiting current, and
regulate a heart rate of the subject by:
driving the electrode device to apply the stimulating and inhibiting currents in each of a plurality of cardiac cycles of the subject in respective series of pulses, each of which pulse series is applied after a delay from a sensed point in the cardiac cycle, and
varying a number of pulses applied per cardiac cycle and a length of a period of application of the respective series of pulses.
2. Apparatus according to claim 1 , wherein the control unit is configured to:
drive the electrode device to configure the stimulating current to induce the action potentials in an efferent therapeutic direction towards a heart of the subject, in the first and the second set of nerve fibers, and
drive the electrode device to configure the inhibiting current to inhibit the induced action potentials traveling in the efferent therapeutic direction in the second set of nerve fibers.
3. Apparatus according to claim 1 , wherein the control unit is configured to increase a number of action potentials traveling in the nerve by decreasing an amplitude of the applied inhibiting current.
4. Apparatus according to claim 1 , wherein the control unit is configured to decrease a number of action potentials traveling in the nerve by increasing an amplitude of the applied inhibiting current.
5. Apparatus according to claim 1 , wherein the condition includes a heart condition of the subject, and wherein the apparatus is configured to treat the heart condition.
6. Apparatus according to claim 5 , wherein the heart condition includes heart failure, and the apparatus is configured to treat the heart failure.
7. Apparatus according to claim 5 , wherein the heart condition includes cardiac arrhythmia, and the apparatus is configured to treat the cardiac arrhythmia.
8. Apparatus according to claim 1 , comprising an override, configured to be used by the subject so as to influence the application by the electrode device of the stimulating and inhibiting currents.
9. Apparatus according to claim 1 , comprising a pacemaker, wherein the control unit is configured to drive the pacemaker to apply pacing pulses to a heart of the subject.
10. Apparatus according to claim 1 , comprising an implantable cardioverter defibrillator (ICD), wherein the control unit is configured to drive the ICD to apply energy to a heart of the subject.
11. Apparatus according to claim 1 , wherein the sensor is configured to receive an electrical signal from the electrode device, and to sense the at least one feature of cardiac activity responsively to the electrical signal.
12. Apparatus according to claim 1 , wherein the electrode device comprises a cathode and a primary set of anodes, and wherein the control unit is configured to drive the cathode to apply the stimulating current, and to drive the primary set of anodes to apply the inhibiting current.
13. Apparatus according to claim 1 , wherein the control unit is configured to configure each of the series of pulses to include about one to 20 pulses.
14. Apparatus according to claim 1 , wherein the control unit is configured to drive the electrode device to configure at least one of the pulses to have a duration of between about one and three milliseconds.
15. Apparatus according to claim 1 , wherein the control unit is configured to drive the electrode device to apply the stimulating and inhibiting currents in each of the series of pulses over a period of between about one and about 200 milliseconds.
16. Apparatus according to claim 1 , wherein the control unit is configured to:
configure the stimulating current to induce the action potentials to travel in a therapeutic direction, and the inhibiting current to inhibit the induced action potentials traveling in the therapeutic direction, and
drive the electrode device to apply to the nerve a second inhibiting current, which is capable of inhibiting device-induced action potentials traveling in a non-therapeutic direction opposite the therapeutic direction in the first and second sets of nerve fibers.
17. Apparatus according to claim 1 , wherein the sensor comprises an electrocardiogram (ECG) monitor, wherein the at least one sensed feature of cardiac activity includes a feature of an ECG and wherein the sensor is configured to sense the feature of the ECG.
18. Apparatus according to claim 17 , wherein the at least one sensed feature of cardiac activity includes an ECG reading indicative of a presence of arrhythmia, and wherein the sensor is configured to sense the ECG reading indicative of the presence of the arrhythmia.
19. Apparatus according to claim 1 , wherein the at least one sensed feature of cardiac activity includes a heart rate of the subject, and wherein the sensor is configured to sense the heart rate.
20. Apparatus according to claim 19 , wherein the at least one sensed feature of cardiac activity includes indications of a plurality of heart rates of the subject at a respective plurality of points in time, and wherein the control unit is configured to receive the indications of the plurality of heart rates and to determine a measure of variability of heart rate responsive thereto.
21. Apparatus according to claim 1 , wherein the nerve includes a vagus nerve of the subject, and wherein the electrode device is configured to be coupled to the vagus nerve.
22. Apparatus according to claim 1 , wherein the sensor comprises a sensor of cardiac output, and wherein the control unit is configured to configure the at least one selected current and regulate the heart rate responsively to the sensed cardiac output.