US6849073B2
Expired / Lapsed
US
⏱️ 0.0 years remaining
Apparatus and method for creating, maintaining, and controlling a virtual electrode used for the ablation of tissue
Assignee: Medtronic Inc
•
Filing: 2002-04-24
•
Granted: 2005-02-01
•
Expires: 2022-04-24
Abstract
Abstract The present invention provides an apparatus and a method for producing a virtual electrode within or upon a tissue to be treated with radio frequency alternating electric current, such tissues including but not limited to liver, lung, cardiac, prostate, breast, and vascular tissues and neoplasms. An apparatus in accord with the present invention includes a supply of a conductive or electrolytic fluid to be provided to the patient, an alternating current generator, and a processor for creating, maintaining, and controlling the ablation process by the interstitial or surficial delivery of the fluid to a tissue and the delivery of electric power to the tissue via the virtual electrode. A method in accord with the present invention includes delivering a conductive fluid to a predetermined tissue ablation site for a predetermined time period, applying a predetermined power level of radio frequency current to the tissue, monitoring at least one of several parameters, and adjusting either the applied power and/or the fluid flow in response to the measured parameters.
Inventors
- 👤 Michael F. Hoey
- 👤 Mark A. Christopherson
- 👤 Steven M. Goetz
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 02:06
CPC Classifications
A; A61; A61B; A61B18/00; A61B18/18; A61B18/04; A61B18/12; A61B18/1206; A61B18/14; A61B18/1402; A61B18/1233; A61B18/1815; A61B2018/00005; A61B2018/00011; A61B2018/00029; A61B2018/00053; A61B2018/00184; A61B2018/00196; A61B2018/00636; A61B2018/00666; A61B2018/00678; A61B2018/00696; A61B2018/00702; A61B2018/00708; A61B2018/00773; A61B2018/00779; A61B2018/00791; A61B2018/00797; A61B2018/00821; A61B2018/00875; A61B2018/1213; A61B2018/1246; A61B2018/1253; A61B2018/1405; A61B2018/1417; A61B2018/1472; A61B2018/1475; A61B2218/00; A61B2218/001; A61B2218/002; A61B2218/007
Claims Analysis
Total Claims: 78
Claim 1
Independent Claim
89 words
A system for ablating tissue of a patient, the system comprising: an electrode; a generator for supplying RF energy to the electrode; a return electrode, the return electrode returning RF energy back from the electrode to the generator; means for measuring a change in impedance to the passage of the RF energy over a predetermined period of time; and means for increasing the power level of RF energy supplied to the electrode by a predetermined amount in response to the measured change in impedance being below a predetermined value.
Claim 2
Independent Claim
89 words
A system for ablating tissue of a patient, the system comprising: an electrode; a generator for supplying RF energy to the electrode; a return electrode, the return electrode returning RF energy back from the electrode to the generator; means for measuring a change in impedance to the passage of the RF energy over a predetermined period of time; and means for increasing the power level of RF energy supplied to the electrode by a predetermined amount in response to the measured change in impedance being below a predetermined value.
Claim 3
Dependent Claim
21 words
The system of claim 1 further comprising a source of conductive fluid, the source supplying the conductive fluid to the electrode.
Claim 4
Dependent Claim
14 words
The system of claim 2 wherein the source of conductive fluid comprises a pump.
Claim 5
Dependent Claim
14 words
The system of claim 2 wherein the source of conductive fluid comprises a container.
Claim 6
Dependent Claim
11 words
The system of claim 4 wherein the container is a bag.
Claim 7
Dependent Claim
11 words
The system of claim 4 wherein the container is a syringe.
Claim 8
Dependent Claim
11 words
The system of claim 2 wherein the conductive fluid is saline.
Claim 9
Dependent Claim
11 words
The system of claim 7 wherein the saline is isotonic saline.
Claim 10
Dependent Claim
11 words
The system of claim 7 wherein the saline is hypertonic saline.
Claim 11
Dependent Claim
13 words
The system of claim 1 wherein the return electrode is a ground pad.
Claim 12
Dependent Claim
16 words
The system of claim 1 wherein a surgical instrument comprises the electrode and the return electrode.
Claim 13
Dependent Claim
25 words
The system of claim 11 wherein the surgical instrument further includes at least one fluid aperture for delivery of a conductive fluid to the electrode.
Claim 14
Dependent Claim
33 words
The system of claim 12 wherein the surgical instrument further includes a fluid lumen in fluid communication with the at least one fluid aperture for delivery of the conductive fluid to the electrode.
Claim 15
Dependent Claim
26 words
The system of claim 12 wherein the surgical instrument further includes at least one fluid aperture for delivery of a conductive fluid to the return electrode.
Claim 16
Dependent Claim
12 words
The system of claim 11 wherein the surgical instrument comprises a forceps.
Claim 17
Dependent Claim
12 words
The system of claim 1 wherein a surgical instrument comprises the electrode.
Claim 18
Dependent Claim
12 words
The system of claim 16 wherein the surgical instrument comprises a needle.
Claim 19
Dependent Claim
12 words
The system of claim 16 wherein the surgical instrument comprises a forceps.
Claim 20
Dependent Claim
12 words
The system of claim 16 wherein the surgical instrument comprises a catheter.
Claim 21
Dependent Claim
12 words
The system of claim 16 wherein the surgical instrument comprises a blade.
Claim 22
Dependent Claim
12 words
The system of claim 16 wherein the surgical instrument comprises a rollerball.
Claim 23
Dependent Claim
37 words
The system of claim 1 further comprising: means for reducing the power level of RF energy supplied to the electrode by a predetermined amount in response to the measured change of impedance being above a predetermined value.
Claim 24
Dependent Claim
37 words
The system of claim 22 further comprising: means for determining the time elapsed since the power level of RF energy supplied to the electrode was last increased by a predetermined amount or reduced by a predetermined amount.
Claim 25
Dependent Claim
32 words
The system of claim 23 further comprising: means for inhibiting an increase in the power level of RF energy for a predetermined period following a prior increase or decrease in power level.
Claim 26
Dependent Claim
32 words
The system of claim 23 further comprising: means for inhibiting a reduction in the power level of RF energy for a predetermined period following a prior increase or decrease in power level.
Claim 27
Dependent Claim
20 words
The system of claim 1 further comprising: means for comparing the increased power level with a predetermined maximum power level.
Claim 28
Dependent Claim
21 words
The system of claim 26 wherein the maximum power level is supplied as an input by the operator of the system.
Claim 29
Dependent Claim
18 words
The system of claim 26 wherein the maximum power level is provided from a memory of the system.
Claim 30
Dependent Claim
21 words
The system of claim 26 wherein the predetermined amount of increase is about twenty percent of the predetermined maximum power level.
Claim 31
Dependent Claim
20 words
The system of claim 1 further comprising: means for comparing a measured impedance level with a predetermined maximum impedance level.
Claim 32
Dependent Claim
21 words
The system of claim 30 wherein the maximum impedance level is supplied as an input by the operator of the system.
Claim 33
Dependent Claim
18 words
The system of claim 30 wherein the maximum impedance level is provided from a memory of the system.
Claim 34
Dependent Claim
27 words
The system of claim 30 wherein the means for increasing the power level is activated if the measured impedance level is less than the maximum impedance level.
Claim 35
Independent Claim
110 words
A method for ablating tissue of a patient, comprising: providing an electrode, a generator for supplying RF energy to the electrode and a return electrode returning RF energy back from the electrode to the generator; applying the electrode to a selected tissue to be ablated; ablating the selected tissue by supplying RF energy to the electrode at a power level; measuring at least one change in impedance to the passage of the RF energy over a predetermined period of time; and increasing the power level of the RF energy supplied to the electrode by a predetermined amount in response to a measured change in impedance being below a predetermined value.
Claim 36
Independent Claim
110 words
A method for ablating tissue of a patient, comprising: providing an electrode, a generator for supplying RF energy to the electrode and a return electrode returning RF energy back from the electrode to the generator; applying the electrode to a selected tissue to be ablated; ablating the selected tissue by supplying RF energy to the electrode at a power level; measuring at least one change in impedance to the passage of the RF energy over a predetermined period of time; and increasing the power level of the RF energy supplied to the electrode by a predetermined amount in response to a measured change in impedance being below a predetermined value.
Claim 37
Dependent Claim
18 words
The method of claim 34 further comprising: supplying conductive fluid to the electrode while ablating the selected tissue.
Claim 38
Dependent Claim
36 words
The method of claim 34 further comprising: reducing the power level of the RF energy supplied to the electrode by a predetermined amount in response to a measured change in impedance being above a predetermined value.
Claim 39
Dependent Claim
35 words
The method of claim 36 further comprising: determining the time elapsed since the power level of RF energy supplied to the electrode was last increased by a predetermined amount or reduced by a predetermined amount.
Claim 40
Dependent Claim
30 words
The method of claim 37 further comprising: inhibiting an increase in the power level of RF energy for a predetermined period following a prior increase or decrease in power level.
Claim 41
Dependent Claim
30 words
The method of claim 37 further comprising: inhibiting a reduction in the power level of RF energy for a predetermined period following a prior increase or decrease in power level.
Claim 42
Dependent Claim
18 words
The method of claim 34 further comprising: comparing the increased power level with a predetermined maximum power level.
Claim 43
Dependent Claim
21 words
The method of claim 40 wherein the maximum power level is supplied as an input by the operator of the system.
Claim 44
Dependent Claim
18 words
The method of claim 40 wherein the maximum power level is provided from a memory of the system.
Claim 45
Dependent Claim
23 words
The method of claim 40 wherein the predetermined amount of increase in power is about twenty percent of the predetermined maximum power level.
Claim 46
Dependent Claim
18 words
The method of claim 34 further comprising: comparing a measured impedance level with a predetermined maximum impedance level.
Claim 47
Dependent Claim
21 words
The method of claim 44 wherein the maximum impedance level is supplied as an input by the operator of the system.
Claim 48
Dependent Claim
18 words
The method of claim 44 wherein the maximum impedance level is provided from a memory of the system.
Claim 49
Dependent Claim
23 words
The method of claim 44 wherein the power level is increased if the measured impedance level is less than the maximum impedance level.
Claim 50
Independent Claim
206 words
A method of ablating a target tissue of a body of a patient, the method comprising: providing an electrode; placing the electrode adjacent the tissue; delivering an RF current power to the tissue through the electrode; measuring a first impedance of the tissue; measuring a second impedance of the tissue following a first predetermined time interval; determining a first impedance rate of change of the tissue during the first predetermined time interval, the first impedance rate of change being the difference between the first impedance measurement and the second impedance measurement divided by the first predetermined time interval; measuring a third impedance of the tissue following a second predetermined time interval; determining a second impedance rate of change of the tissue during the second predetermined time interval, the second impedance rate of change being the difference between the second impedance measurement and the third impedance measurement divided by the second predetermined time interval; determining an average impedance rate of change of the tissue, the average rate of change being the average of the first impedance rate of change and the second impedance rate of change; and adjusting the delivery of RF current power to the tissue in response to the determined average impedance rate of change.
Claim 51
Independent Claim
206 words
A method of ablating a target tissue of a body of a patient, the method comprising: providing an electrode; placing the electrode adjacent the tissue; delivering an RF current power to the tissue through the electrode; measuring a first impedance of the tissue; measuring a second impedance of the tissue following a first predetermined time interval; determining a first impedance rate of change of the tissue during the first predetermined time interval, the first impedance rate of change being the difference between the first impedance measurement and the second impedance measurement divided by the first predetermined time interval; measuring a third impedance of the tissue following a second predetermined time interval; determining a second impedance rate of change of the tissue during the second predetermined time interval, the second impedance rate of change being the difference between the second impedance measurement and the third impedance measurement divided by the second predetermined time interval; determining an average impedance rate of change of the tissue, the average rate of change being the average of the first impedance rate of change and the second impedance rate of change; and adjusting the delivery of RF current power to the tissue in response to the determined average impedance rate of change.
Claim 52
Dependent Claim
124 words
The method of claim 48 further comprising: measuring a fourth impedance of the tissue following a third predetermined time interval; determining a third impedance rate of change of the tissue during the third predetermined time interval, the third impedance rate of change being the difference between the third impedance measurement and the fourth impedance measurement divided by the third predetermined time interval; determining a second average impedance rate of change of the tissue, the second average rate of change being the average of the first impedance rate of change, the second impedance rate of change and the third impedance rate of change; and adjusting the delivery of RF current power to the tissue in response to the determined second average impedance rate of change.
Claim 53
Dependent Claim
16 words
The method of claim 48 further comprising the delivery of a conductive fluid to the electrode.
Claim 54
Dependent Claim
11 words
The method of claim 50 wherein the conductive fluid is saline.
Claim 55
Dependent Claim
11 words
The method of claim 51 wherein the saline is isotonic saline.
Claim 56
Dependent Claim
11 words
The method of claim 51 wherein the saline is hypertonic saline.
Claim 57
Dependent Claim
12 words
The method of claim 48 wherein a surgical instrument comprises the electrode.
Claim 58
Dependent Claim
14 words
The method of claim 54 wherein the surgical instrument is a bipolar surgical instrument.
Claim 59
Dependent Claim
14 words
The method of claim 54 wherein the surgical instrument is a monopolar surgical instrument.
Claim 60
Dependent Claim
12 words
The method of claim 54 wherein the surgical instrument comprises a needle.
Claim 61
Dependent Claim
12 words
The method of claim 54 wherein the surgical instrument comprises a forceps.
Claim 62
Dependent Claim
13 words
A The method of claim 54 wherein the surgical instrument comprises a catheter.
Claim 63
Dependent Claim
12 words
The method of claim 54 wherein the surgical instrument comprises a blade.
Claim 64
Dependent Claim
12 words
The method of claim 54 wherein the surgical instrument comprises a rollerball.
Claim 65
Independent Claim
213 words
A method of ablating a target tissue of a body of a patient, the method comprising: providing an electrode; placing the electrode adjacent the tissue; delivering an RF current power to the tissue through the electrode; measuring a first impedance of the tissue; measuring a second impedance of the tissue following a first predetermined time interval; determining a first impedance rate of change of the tissue during the first predetermined time interval, the first impedance rate of change being the difference between the first impedance measurement and the second impedance measurement divided by the first predetermined time interval; measuring a third impedance of the tissue; measuring a fourth impedance of the tissue following a second predetermined time interval; determining a second impedance rate of change of the tissue during the second predetermined time interval, the second impedance rate of change being the difference between the third impedance measurement and the fourth impedance measurement divided by the second predetermined time interval; determining an average impedance rate of change of the tissue, the average rate of change being the average of the first impedance rate of change and the second impedance rate of change; and adjusting the delivery of RF current power to the tissue in response to the determined average impedance rate of change.
Claim 66
Independent Claim
213 words
A method of ablating a target tissue of a body of a patient, the method comprising: providing an electrode; placing the electrode adjacent the tissue; delivering an RF current power to the tissue through the electrode; measuring a first impedance of the tissue; measuring a second impedance of the tissue following a first predetermined time interval; determining a first impedance rate of change of the tissue during the first predetermined time interval, the first impedance rate of change being the difference between the first impedance measurement and the second impedance measurement divided by the first predetermined time interval; measuring a third impedance of the tissue; measuring a fourth impedance of the tissue following a second predetermined time interval; determining a second impedance rate of change of the tissue during the second predetermined time interval, the second impedance rate of change being the difference between the third impedance measurement and the fourth impedance measurement divided by the second predetermined time interval; determining an average impedance rate of change of the tissue, the average rate of change being the average of the first impedance rate of change and the second impedance rate of change; and adjusting the delivery of RF current power to the tissue in response to the determined average impedance rate of change.
Claim 67
Dependent Claim
131 words
The method of claim 62 further comprising: measuring a fifth impedance of the tissue; measuring a sixth impedance of the tissue following a third predetermined time interval; determining a third impedance rate of change of the tissue during the third predetermined time interval, the third impedance rate of change being the difference between the fifth impedance measurement and the sixth impedance measurement divided by the third predetermined time interval; determining a second average impedance rate of change of the tissue, the second average rate of change being the average of the first impedance rate of change, the second impedance rate of change and the third impedance rate of change; and adjusting the delivery of RF current power to the tissue in response to the determined second average impedance rate of change.
Claim 68
Dependent Claim
16 words
The method of claim 62 further comprising the delivery of a conductive fluid to the electrode.
Claim 69
Dependent Claim
11 words
The method of claim 64 wherein the conductive fluid is saline.
Claim 70
Dependent Claim
11 words
The method of claim 65 wherein the saline is isotonic saline.
Claim 71
Dependent Claim
11 words
The method of claim 65 wherein the saline is hypertonic saline.
Claim 72
Dependent Claim
12 words
The method of claim 62 wherein a surgical instrument comprises the electrode.
Claim 73
Dependent Claim
13 words
The method of claim 68 wherein the surgical instrument includes the return electrode.
Claim 74
Dependent Claim
12 words
The method of claim 68 wherein the surgical instrument comprises a needle.
Claim 75
Dependent Claim
12 words
The method of claim 68 wherein the surgical instrument comprises a forceps.
Claim 76
Dependent Claim
12 words
The method of claim 68 wherein the surgical instrument comprises a catheter.
Claim 77
Dependent Claim
12 words
The method of claim 68 wherein the surgical instrument comprises a blade.
Claim 78
Dependent Claim
12 words
The method of claim 68 wherein the surgical instrument comprises a rollerball.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 2008-02-01 | 2008-08-02 | 2009-02-01 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2012-02-01 | 2012-08-02 | 2013-02-01 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2016-02-01 | 2016-08-02 | 2017-02-01 | $7700.00 | Window Closed / Lapsed |