Methods and systems for thermally-induced renal neuromodulation

• US 9,345,900 B2
• Filed: 06/26/2008
• Issued: 05/24/2016
• Est. Priority Date: 06/28/2006
• Status: Active Grant

• Current Assignee: Medtronic Ardian Luxembourg SARL (Medtronic Plc)
• Original Assignee: Medtronic Ardian Luxembourg SARL (Medtronic Plc)
• Inventors: Wu, Andrew, Clark, Benjamin J., Thai, Erik, Zadno, Nicolas, Zarins, Denise
• Primary Examiner(s): HENSON, DEVIN B
• Application Number:
  US12/147,191
• Publication Number:
  US 20080255642A1
• Time in Patent Office: 2,889 Days
• Field of Search: 600/547, 600/549, 606/31, 606/34, 606/41, 607/2, 607/3, 607/44, 607/99, 607/102
• US Class Current: 1/1
• CPC Class Codes: A61B 18/12 by passing a current through the tissue to be heated, e.g. high-frequency current
• CPC Class Codes: A61B 18/1206 Generators therefor
• CPC Class Codes: A61B 18/1233 with circuits for assuring patient safety
• CPC Class Codes: A61B 18/14 Probes or electrodes therefor
• CPC Class Codes: A61B 18/1492 having a flexible, catheter-like structure, e.g. for heart ablation A61B18/1477 takes precedence
• CPC Class Codes: A61B 18/1815 using microwaves
• CPC Class Codes: A61B 2017/00084 Temperature
• CPC Class Codes: A61B 2017/22054 with two balloons
• CPC Class Codes: A61B 2017/22068 Centering
• CPC Class Codes: A61B 2018/00023 closed, i.e. without wound contact by the fluid
• CPC Class Codes: A61B 2018/00214 Expandable means emitting energy, e.g. by elements carried thereon
• CPC Class Codes: A61B 2018/0022 Balloons
• CPC Class Codes: A61B 2018/00279 deployable
• CPC Class Codes: A61B 2018/00404 Blood vessels other than those in or around the heart
• CPC Class Codes: A61B 2018/00434 Neural system
• CPC Class Codes: A61B 2018/00505 Urinary tract
• CPC Class Codes: A61B 2018/00511 Kidney
• CPC Class Codes: A61B 2018/00577 Ablation
• CPC Class Codes: A61B 2018/00636 Sensing and controlling the application of energy
• CPC Class Codes: A61B 2018/00666 using a threshold value
• CPC Class Codes: A61B 2018/00702 : Power or energy
• CPC Class Codes: A61B 2018/00714 : Temperature
• CPC Class Codes: A61B 2018/00755 : Resistance or impedance
• CPC Class Codes: A61B 2018/00779 : Power or energy
• CPC Class Codes: A61B 2018/00791 : Temperature
• CPC Class Codes: A61B 2018/00875 : Resistance or impedance
• CPC Class Codes: A61B 2018/00994 : combining two or more different kinds of non-mechanical energy or combining one or more non-mechanical energies with ultrasound
• CPC Class Codes: A61B 2018/143 : multiple needles
• CPC Class Codes: A61B 2018/1432 : curved
• CPC Class Codes: A61B 2018/144 : Wire
• CPC Class Codes: A61B 2018/1475 : Electrodes retractable in or deployable from a housing
• CPC Class Codes: A61B 90/39 : Markers, e.g. radio-opaque or breast lesions markers
• CPC Class Codes: A61F 2007/0056 : for cooling
• CPC Class Codes: A61F 2007/0075 : using a Peltier element, e.g. near the spot to be heated or cooled
• CPC Class Codes: A61F 2007/126 : for invasive application, e.g. for introducing into blood vessels
• CPC Class Codes: A61F 7/007 : characterised by electric heating
• CPC Class Codes: A61F 7/10 : Cooling bags, e.g. ice-bags
• CPC Class Codes: A61F 7/12 : Devices for heating or cooling internal body cavities
• CPC Class Codes: A61M 2025/0087 : Multiple injection needles protruding laterally from the distal tip
• CPC Class Codes: A61M 2025/0092 : Single injection needle protruding laterally from the distal tip
• CPC Class Codes: A61M 2025/1047 : having centering means, e.g. balloons having an appropriate shape
• CPC Class Codes: A61M 25/0084 : being one or more injection needles
• CPC Class Codes: A61M 25/04 : in the body, e.g. expansible A61M25/10, A61M16/0488 take precedence
• CPC Class Codes: A61M 25/10 : Balloon catheters A61M25/0125 takes precedence; embolectomy A61B17/22032; retractors A61B17/02; inflatable balloons for placing stents or stent-grafts A61F2/958 ; stomach balloons for treatment of obesity A61F5/0003; oesophagal tubes A61J15/00
• CPC Class Codes: A61N 1/0558 : Anchoring or fixation means therefor
• CPC Class Codes: A61N 1/057 : Anchoring means; Means for fixing the head inside the heart
• CPC Class Codes: A61N 1/06 : for high-frequency therapy
• CPC Class Codes: A61N 1/36007 : of urogenital or gastrointestinal organs, e.g. for incontinence control
• CPC Class Codes: A61N 1/36017 : with leads or electrodes penetrating the skin
• CPC Class Codes: A61N 1/403 : for thermotherapy, e.g. hyperthermia
• CPC Class Codes: A61N 2007/0026 : Stimulation of nerve tissue
• CPC Class Codes: A61N 2007/003 : Destruction of nerve tissue
• CPC Class Codes: A61N 5/0601 : Apparatus for use inside the body
• CPC Class Codes: A61N 5/0622 : Optical stimulation for exciting neural tissue
• CPC Class Codes: A61N 7/02 : Localised ultrasound hyperthermia hyperthermia in general A61F7/00
• CPC Class Codes: A61N 7/022 : intracavitary

Abstract

Methods and system are provided for thermally-induced renal neuromodulation. Thermally-induced renal neuromodulation may be achieved via direct and/or via indirect application of thermal energy to heat or cool neural fibers that contribute to renal function, or of vascular structures that feed or perfuse the neural fibers. In some embodiments, parameters of the neural fibers, of non-target tissue, or of the thermal energy delivery element, may be monitored via one or more sensors for controlling the thermally-induced neuromodulation. In some embodiments, protective elements may be provided to reduce a degree of thermal damage induced in the non-target tissues. In some embodiments, thermally-induced renal neuromodulation is achieved via delivery of a pulsed thermal therapy.

Claims

1. A method for thermally inducing neuromodulation in a human patient, the method comprising:

positioning an electrode within a renal blood vessel of the human patient;

determining a tissue site suitable for treatment within the renal blood vessel;

delivering energy via the electrode to a renal nerve of the patient proximate to or within the tissue site;

increasing the energy delivered to the electrode at a generally constant rate to a predetermined first power level over a first period of time;

maintaining the energy delivered to the electrode at the first power level for a second period of time after reaching the first power level;

measuring a temperature value related to a wall of the renal blood vessel or the electrode; and

if the temperature value is less than a preset temperature threshold and a measured impedance value s less than a predetermined impedance threshold, then increasing the energy delivered to the electrode until a target maximum power level is reached.

2. The method of claim 1 wherein positioning an electrode within a renal blood vessel includes positioning an electrode in contact with the wall of the renal blood vessel.

3. The method of claim 1, further comprising:

deriving an average temperature based on the temperature value; and

if the average temperature is less than the preset temperature threshold, then increasing the energy delivered to the electrode to a second power level.

4. The method of claim 3 wherein increasing the energy delivered to the electrode to a second power level includes increasing the energy delivered to the electrode to a second power level by a predetermined amount.

5. The method of claim 1 wherein increasing the energy delivered to the electrode includes increasing the energy delivered to the electrode in predetermined power increments.

6. The method of claim 5 wherein increasing the energy delivered to the electrode in predetermined power increments comprises increasing the energy delivered to the electrode in increments of about 1 watt.

7. The method of claim 1 wherein the preset temperature threshold is from about 60 degrees Celsius to about 75 degrees Celsius.

8. The method of claim 1 wherein the preset temperature threshold is about 65 degrees Celsius.

9. The method of claim 1 wherein the preset threshold temperature is a first threshold temperature, and wherein the method further includes ceasing the energy delivered to the electrode if the temperature value exceeds a second threshold temperature greater than the first threshold temperature.

10. The method of claim 9 wherein the second threshold temperature is about 85 degrees Celsius.

11. The method of claim 1 wherein the preset threshold temperature is a first threshold temperature, and wherein the method further includes decreasing the energy delivered to the electrode if the temperature value exceeds a second threshold temperature greater than the first threshold temperature.

12. The method of claim 11 wherein the second threshold temperature is about 70 degrees Celsius.

13. The method of claim 11 wherein decreasing the energy delivered to the electrode further comprises decreasing the energy delivered to the electrode in predetermined power increments.

14. The method of claim 1 wherein measuring a temperature value related to the wall of the renal blood vessel or the electrode further comprises:

measuring a voltage associated with the energy delivered using the electrode; and

determining a temperature value based on the measured voltage.

15. The method of claim 1 wherein measuring a temperature value related to the wall of the renal blood vessel or the electrode further comprises measuring at least one of real time temperature, average temperature, temperature offset, and rate of temperature change.

16. The method of claim 1, further comprising adjusting the first and second period of time based on the temperature value.

17. The method of claim 1, further comprising issuing an alarm when the target maximum power level is reached.

18. The method of claim 1 wherein the target maximum power level is from about 8 watts to about 10 watts.

19. The method of claim 1, further comprising terminating energy delivered to the electrode when the temperature value reaches a maximum temperature threshold.

20. The method of claim 19 wherein terminating energy delivered to the electrode when the temperature value reaches a maximum temperature threshold further comprises terminating energy delivered to the electrode when the temperature value reaches a rate of change threshold.

21. The method of claim 1, further comprising terminating energy delivered to the electrode when the measured impedance value reaches the predetermined impedance threshold.

22. The method of claim 21 wherein terminating energy delivered to the electrode when the measured impedance value reaches the predetermined impedance threshold further comprises terminating energy delivered to the electrode when the measured impedance value is above about 500 Ohms.

23. The method of claim 21 wherein terminating energy delivered to the electrode when the measured impedance value reaches the predetermined impedance threshold further comprises terminating energy delivered to the electrode when the measured impedance value reaches a relative threshold.

24. The method of claim 23, further comprising storing a baseline impedance value as the relative threshold.

25. The method of claim 24, wherein storing a baseline impedance value as the relative threshold further comprises storing an initial impedance value measured prior to the delivery of energy.

26. The method of claim 1, further comprising measuring a treatment time from when energy delivery commences, and wherein the method further comprises terminating energy delivered to the electrode when the treatment time reaches a maximum time threshold.

27. The method of claim 26 wherein terminating energy delivered to the electrode when the treatment time reaches a maximum time threshold comprises terminating energy delivered to the electrode when the treatment time reaches about 2 minutes.

28. A method for controlling energy delivery via an electrode positioned within a patient'"'"'s renal blood vessel proximate to a wall thereof, the method comprising:

increasing energy delivery at a generally constant rate to a predetermined first power level over a first period of time;

maintaining energy delivery at a desired power level for a second period of time after reaching the first power level;

measuring a temperature related to the wall of the renal blood vessel;

deriving an average temperature based on the measured temperature during the second period of time;

if the average temperature is less than a preset temperature threshold and a measured impedance value is less than a predetermined impedance threshold, then increasing energy delivery from the first power level to a second power level; and

repeating cycles of (a) maintaining the energy delivery at a desired power level for a period of time after reaching a current power level and (b) increasing energy delivery to another power level from the current power level if the average temperature is less than the preset temperature threshold and the measured impedance value is less than the predetermined impedance threshold until a target maximum power level of the delivered energy is reached.

29. The method of claim 28 wherein the target maximum power level is from about 8 watts to about 10 watts.

30. The method of claim 28, further comprising:

deriving an average impedance based on the measured impedance value at multiple instances during the treatment period;

determining a baseline impedance value; and

if the average impedance value during the treatment period is greater than the baseline impedance value, reducing or terminating energy delivery.

31. The method of claim 30 wherein determining a baseline impedance value comprises storing an initial impedance value measured prior to the delivery of energy.

32. The method of claim 28, further comprising maintaining the energy delivery at approximately the target maximum power level for a desired treatment period.

33. The method of claim 32, further comprising decreasing the energy delivery by a preselected value from the target maximum power level during the treatment period if the average temperature during the treatment period is greater than a preset average temperature threshold.

34. The method of claim 33 wherein the preset average temperature threshold is about 70 degrees Celsius.

35. The method of claim 28 wherein increasing energy delivery to another power level from the current power level further comprises increasing energy delivery to another power level in predetermined power increments.

36. The method of claim 28, further comprising maintaining the energy delivery generally at the first power level if the average temperature is greater than or equal to the preset temperature threshold.

37. The method of claim 36 wherein the preset temperature threshold is about 65 degrees Celsius.

38. The method of claim 28 wherein the preset temperature threshold is a first temperature threshold, and wherein the method further includes ceasing the energy delivery if the measured temperature equals or exceeds a second temperature threshold greater than the first temperature threshold.

39. The method of claim 38 wherein the second temperature threshold is about 85 degrees Celsius.

40. The method of claim 28, further comprising deriving a rate of change for the temperature from the measured temperature.

41. The method of claim 40, further comprising issuing an alarm based on a comparison of the derived rate of change and a rate of change threshold.

42. The method of claim 40, further comprising controlling the energy delivered to the electrode based on the derived rate of change.