Electrical muscle controller and pacing with hemodynamic enhancement
View Patent ↗A method of modifying the force of contraction of at least a portion of a heart chamber is provided. A non-excitatory electric field of given duration is applied, at a delay after an activation of the heart, which increase the force of contraction by at least 5%. Apparatus is also provided for pacing with hemodynamic improvement. Circuitry applies an extended pacing signal to electrodes to pace the heart, the extended pacing signal having an overall duration greater than 8 ms from a time of initiation of application of that portion of the signal that initiates action potential propagation. The signal includes a train of biphasic pulses having pulse durations of at least 1 ms, and the signal has an amplitude that is at least three times as great as a threshold for pacing the heart and that is sufficient neither for cardioversion nor for defibrillation. Other embodiments are also described.
1. An apparatus comprising: sensing circuitry configured for sensing electrical activity of a muscle segment of a heart; one or more implantable electrodes, wherein said electrodes are adapted to convey an electrical signal to the muscle segment of the heart; and pacing circuitry for pacing the heart, wherein said pacing circuitry is adapted to drive the electrodes to apply the signal to the segment by driving an electrical current into the segment, the current having an amplitude of at least 3 mA and less than 20 mA, and a signal duration, in a cardiac cycle, of between 10 and 140 msec, wherein the signal is applied in response to the sensing with a delay relative to the preceding sensed electrical activity.
2. The apparatus according to claim 1 , wherein the amplitude of the current is less than 8 mA.
3. The apparatus according to claim 2 , wherein the amplitude of the current is less than 5 mA.
4. The apparatus according to claim 1 , wherein the duration is between 20 and 100 msec.
5. The apparatus according to claim 1 , wherein the pacing circuitry is configured to apply the current with a strength of between 50 and 500 micro joules.
6. The apparatus according to claim 1 , wherein the pacing circuitry is configured to drive the current into a left ventricle.
7. The apparatus according to claim 1 , wherein the pacing circuitry is configured to drive the current into a right ventricle.
8. The apparatus according to claim 1 , wherein the pacing circuitry is configured to drive the current into a left atrium.
9. The apparatus according to claim 1 , wherein the pacing circuitry is configured to drive the current into a right atrium.
10. The apparatus according to claim 1 , wherein the pacing circuitry is configured to apply the signal as a constant amplitude pulse.
11. The apparatus according to claim 1 , wherein the pacing circuitry is configured to apply the signal as a biphasic pulse form.
12. The apparatus according to claim 1 , wherein the pacing circuitry is configured to apply the current as an AC electric field.
13. The apparatus according to claim 1 , wherein the pacing circuitry is configured to apply the signal as a train of pulses.
14. The apparatus according to claim 1 , wherein the pacing circuitry is configured to apply the signal only once every number of heart beats.
15. The apparatus according to claim 1 , wherein the pacing circuitry configures the signal to not disrupt regular activation of the heart.
16. The apparatus according to claim 1 , wherein the pacing circuitry is configured to apply the signal in a substantial number of cardiac cycles.
17. A method comprising; sensing electrical activity of a muscle segment of a heart; implanting one or more electrodes in a subject; and driving, by pacing circuitry for pacing a heart of the subject, the electrodes to apply an electrical signal to a muscle segment of the heart by driving an electrical current into the segment, the current having an amplitude of at least 3 mA and less than 20 mA, and a signal duration, in a cardiac cycle, of between 10 and 140 msec, wherein the signal is applied in response to the sensing with a delay relative to the preceding sensed electrical activity.
18. The method according to claim 17 , wherein the amplitude of the current is less than 8 mA.
19. The method according to claim 18 , wherein the amplitude of the current is less than 5 mA.
20. The method according to claim 17 , wherein the duration is between 20 and 100 msec.
21. The method according to claim 17 , wherein driving comprises driving the electrodes to apply the current with a strength of between 50 and 500 micro joules.
22. The method according to claim 17 , wherein driving comprises driving the current into a left ventricle.
23. The method according to claim 17 , wherein driving comprises driving the current into a right ventricle.
24. The method according to claim 17 , wherein driving comprises driving the current into a left atrium.
25. The method according to claim 17 , wherein driving comprises driving the current into a right atrium.
26. The method according to claim 17 , wherein driving comprises driving the electrodes to apply the signal as a constant amplitude pulse.
27. The method according to claim 17 , wherein driving comprises driving the electrodes to apply the signal as a biphasic pulse form.
28. The method according to claim 17 , wherein driving comprises driving the electrodes to apply the current as an AC electric field.
29. The method according to claim 17 , wherein driving comprises driving the electrodes to apply the signal as a train of pulses.
30. The method according to claim 17 , wherein driving comprises driving the electrodes to apply only once every number of heart beats.
31. The method according to claim 17 , wherein driving comprises configuring the signal to not disrupt regular activation of the heart.
32. The method according to claim 17 , wherein driving comprises driving the electrodes to apply the signal in a substantial number of cardiac cycles.
33. The apparatus according to claim 1 , wherein said pacing circuitry is configured to pace a heart as a replacement or assistance for natural pacing.
34. The apparatus according to claim 1 , wherein said apparatus includes a battery and is implantable.