Signal delivery through the right ventricular septum
View Patent ↗A method is provided for use with a human subject. The method includes accessing a cardiac site via a vena cava of the subject, and alleviating heart failure of the subject by applying to the cardiac site, during a refractory period of the site, a refractory-period signal that affects the left ventricle of the subject's heart. Other embodiments are also described.
1. Apparatus for applying a signal to a heart of a human subject, comprising: one or more electrodes, configured to be passed by a catheter through a vena cava of the subject and coupled to a cardiac site of the right ventricle or the right ventricle septum of the subject; a circuitry for determining a start time of or a time within a refractory period; and a control unit, configured to alleviate heart failure of the subject by driving the one or more electrodes to apply to said cardiac site, during said determined refractory period of the site, a signal that directly affects a left ventricle of the heart and is non-excitatory thereto.
2. The apparatus according to claim 1 , wherein the one or more electrodes are configured to be implanted from a right ventricle of the subject into an inter-ventricular septum of the subject.
3. The apparatus according to claim 2 , wherein at least one of the electrodes is configured to penetrate to a depth of 5-10 mm in the septum.
4. The apparatus according to claim 2 , wherein at least one of the electrodes is configured to penetrate to a depth of 10-20 mm in the septum.
5. The apparatus according to claim 2 , wherein at least one of the electrodes is configured to penetrate to a depth of 20-25 mm in the septum.
6. The apparatus according to claim 2 , wherein at least one of the electrodes is configured to penetrate through the septum and emerge in the left ventricle.
7. The apparatus according to claim 2 , wherein at least one of the electrodes comprises a coil electrode.
8. The apparatus according to claim 2 , wherein at least one of the electrodes comprises a screw electrode, configured to be screwed into the septum.
9. The apparatus according to claim 8 , wherein the screw electrode comprises a bipolar screw electrode.
10. The apparatus according to claim 1 , wherein the control unit is operative to configure the signal to be capable of modifying contractility of a portion of the heart.
11. The apparatus according to claim 10 , wherein the control unit is operative to configure the signal to be capable of increasing contractility of the left ventricle of the heart.
12. The apparatus according to claim 10 , wherein the control unit is operative to configure the signal to be capable of modifying contractility of an inter-ventricular septum of the heart.
13. The apparatus according to claim 10 , wherein the control unit is operative to configure the signal to be capable of modifying contractility of a right ventricle of the heart.
14. The apparatus according to claim 10 , wherein the control unit is operative to configure the signal to be capable of increasing contractility of the portion of the heart.
15. The apparatus according to claim 10 , wherein the control unit is operative to configure the signal to be capable of decreasing contractility of the portion of the heart.
16. The apparatus according to claim 15 , wherein the control unit is operative to configure the signal to be capable of decreasing contractility of an inter-ventricular septum of the heart.
17. The apparatus according to claim 1 , wherein the control unit is configured to drive the one or more electrodes to apply a pacing signal to the site during an excitatory period of a cardiac cycle, and to apply the refractory-period signal during a refractory period of the same cardiac cycle.
18. The apparatus according to claim 17 , wherein the control unit is configured to drive the one or more electrodes to apply the refractory-period signal with no delay following application of the pacing signal.
19. The apparatus according to claim 17 , wherein the control unit is configured to drive the one or more electrodes to apply the refractory-period signal following a delay after application of the pacing signal.
20. The apparatus according to claim 1 , wherein the control unit is configured to receive a sensed signal indicative of electrical activity of the heart at a sensing site, and to drive the one or more electrodes to apply the refractory-period signal in response to the sensed signal.
21. The apparatus according to claim 20 , comprising a sensing electrode which is separate from the one or more electrodes, wherein the control unit is configured to receive the sensed signal from the sensing electrode.
22. The apparatus according to claim 20 , wherein the control unit is configured to receive the sensed signal from one of the one or more electrodes, and to drive the one of the one or more electrodes to apply the refractory-period signal in response to the sensed signal.
23. The apparatus according to claim 1 , wherein the control unit configures the refractory-period signal to include a series of pulses which are greater than 8 mA.
24. The apparatus according to claim 23 , wherein the control unit configures the refractory-period signal to include a series of pulses which are greater than 10 mA.
25. The apparatus according to claim 1 , wherein the control unit is configured to drive the one or more electrodes to apply the refractory-period signal chronically.
26. The apparatus according to claim 25 , wherein the control unit is operative to configure the refractory-period signal to engender long-term alleviation of the heart failure.
27. The apparatus according to claim 1 , wherein the control unit configures the refractory-period signal to include a plurality of pulses that are greater than 1 mJ.
28. The apparatus according to claim 27 , wherein the control unit configures the refractory-period signal to include a plurality of pulses that are greater than 5 mJ.
29. The apparatus according to claim 1 , wherein the control unit is configured to detect arrhythmia of the heart, and to drive at least one of the one or more electrodes to apply an anti-arrhythmic signal in response thereto.
30. The apparatus according to claim 29 , wherein the control unit is configured to detect fibrillation of the heart, and to drive the at least one of the electrodes to apply a defibrillating signal to the cardiac site in response to detecting fibrillation.
31. The apparatus according to claim 1 , wherein said cardiac site is a cardiac site of the right ventricle septum of the subject.
32. The apparatus according to claim 31 , wherein the signal applied to the right ventricle septum of the subject increases contractility efficacy of the left ventricle.
33. The apparatus according to claim 1 , wherein the control unit is operative to configure the refractory-period signal such that it increases cardiac output of the heart.
34. The apparatus according to claim 1 , wherein the control unit is configured to drive the one or more electrodes to apply a series of biphasic pulses.
35. The apparatus according to claim 1 , wherein the control unit is configured to drive the one or more electrodes to apply a series of generally square pulses.
36. The apparatus according to claim 1 , wherein the control unit is configured to drive the one or more electrodes to apply a series of pulses at a rate greater than 50 Hz.
37. The apparatus according to claim 1 , wherein the control unit is configured to drive the one or more electrodes to apply a series of pulses at a rate less than 100 Hz.
38. The apparatus according to claim 1 , wherein the control unit is configured to drive the one or more electrodes to apply a series of pulses at a rate between 50 Hz and 100 Hz.
39. The apparatus according to claim 1 , wherein the control unit is configured to drive the one or more electrodes to apply the signal to a site at or adjacent to an intersection of an interventricular septum and a right ventricular free wall.
40. The apparatus according to claim 1 , wherein at least one of the electrodes comprises a material selected from the group consisting of: titanium coated with iridium oxide, titanium coated with titanium nitride, platinum iridium coated with iridium oxide, platinum iridium coated with titanium nitride, platinum iridium coated with sintered platinum, titanium, platinum iridium, and pyrolytic carbon.
41. The apparatus according to claim 1 , wherein at least one of the electrodes is shaped to define an effective external surface area of between 30 mm 2 and 250 mm 2 .
42. The apparatus according to claim 1 , wherein at least one of the electrodes has an impedance that is between 50 Ohms and 1000 Ohms.
43. The apparatus according to claim 1 , wherein at least one of the electrodes has an impedance that is between 200 Ohms and 700 Ohms.
44. The apparatus according to claim 1 , wherein at least one of the electrodes has a capacitance between 300 and 3000 microfarads.
45. The apparatus according to claim 1 , wherein the refractory-period signal includes an excitatory-tissue control (ETC) signal, and wherein the control unit is configured to drive the one or more electrodes to apply the ETC signal to the cardiac site.
46. The apparatus according to claim 1 , wherein the one or more electrodes comprise a plurality of electrodes, configured to be implanted at a respective plurality of cardiac sites.
47. The apparatus according to claim 1 , wherein the one or more electrodes comprise a bipolar electrode.
48. The apparatus according to claim 1 , wherein the one or more electrodes comprise a monopolar electrode.
49. The apparatus according to claim 1 , wherein the control unit configures the refractory-period signal to include a series of biphasic pulses.
50. The apparatus according to claim 1 , including a plurality of electrodes, and wherein the control system is operable to apply different signals to one or more of the electrodes.