US6736810B2
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: 2001-07-11
•
Granted: 2004-05-18
•
Expires: 2021-07-11
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
2026-10-24 07:45
CPC Classifications
A; A61; A61B; A61B18/00; A61B18/18; A61B18/04; A61B18/12; A61B18/14; A61B18/1206; 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
171 words
A system for ablating a target tissue of a body of a patient, comprising: a surgical instrument including an ablation electrode for delivery of RF current to the tissue and a fluid aperture for delivery of conductive fluid adjacent the ablation electrode; a return electrode; an RF current generator coupled to the ablation and return electrodes to deliver RE current between the ablation and return electrodes; a fluid source coupled to the fluid aperture to deliver the conductive fluid to the fluid aperture at a defined rate; an impedance measurer coupled to the ablation and return electrodes to measure rate of change of impedance between the ablation and return electrodes during delivery of the RF current; and a fluid flow controller coupled to the fluid source and adapted to progressively adjust the rate of delivery of the conductive fluid in response to the measured time rate of change of the impedance between the ablation and return electrodes based upon a pre-determined correlation between fluid flow rate and impedance rate of change.
Claim 2
Independent Claim
171 words
A system for ablating a target tissue of a body of a patient, comprising: a surgical instrument including an ablation electrode for delivery of RF current to the tissue and a fluid aperture for delivery of conductive fluid adjacent the ablation electrode; a return electrode; an RF current generator coupled to the ablation and return electrodes to deliver RE current between the ablation and return electrodes; a fluid source coupled to the fluid aperture to deliver the conductive fluid to the fluid aperture at a defined rate; an impedance measurer coupled to the ablation and return electrodes to measure rate of change of impedance between the ablation and return electrodes during delivery of the RF current; and a fluid flow controller coupled to the fluid source and adapted to progressively adjust the rate of delivery of the conductive fluid in response to the measured time rate of change of the impedance between the ablation and return electrodes based upon a pre-determined correlation between fluid flow rate and impedance rate of change.
Claim 3
Dependent Claim
30 words
The system of claim 1 , wherein the flow controller increases fluid flow in response to an excessive rate of increase of the impedance between the ablation and return electrodes.
Claim 4
Dependent Claim
16 words
The system of claim 1 or claim 2 , wherein the fluid source comprises a pump.
Claim 5
Dependent Claim
12 words
The system of claim 1 , wherein the conductive fluid is saline.
Claim 6
Dependent Claim
12 words
The system of claim 4 , wherein the saline is isotonic saline.
Claim 7
Dependent Claim
12 words
The system of claim 4 , wherein the saline is hypertonic saline.
Claim 8
Dependent Claim
17 words
The system of claim 1 or claim 2 , wherein the return electrode is a ground pad.
Claim 9
Dependent Claim
19 words
The system of claim 1 or claim 2 , wherein the return electrode is mounted to the surgical instrument.
Claim 10
Dependent Claim
16 words
The system of claim 8 , wherein the return electrode serves as a second ablation electrode.
Claim 11
Dependent Claim
25 words
The system of claim 9 , wherein the surgical instrument further includes a fluid aperture for delivery of the conductive fluid adjacent the return electrode.
Claim 12
Dependent Claim
32 words
The system of claim 10 , wherein the surgical instrument further includes a fluid lumen in fluid communication with the fluid aperture for delivery of the conductive fluid adjacent the return electrode.
Claim 13
Dependent Claim
35 words
The system of claim 1 or claim 2 , wherein the surgical instrument further includes a fluid lumen in fluid communication with the fluid aperture for delivery of the conductive fluid adjacent the ablation electrode.
Claim 14
Dependent Claim
22 words
The system of claim 1 or claim 2 , wherein the impedance measurer includes means for measuring impedances at predefined time intervals.
Claim 15
Independent Claim
139 words
A method of ablating a target tissue of a body of a patient, comprising: selecting a surgical instrument including an ablation electrode for delivery of RF current to the tissue and a fluid aperture for delivery of conductive fluid adjacent the ablation electrode; placing the ablation electrode adjacent the target tissue; delivering RF current between the ablation electrode and a return electrode; delivering the conductive fluid to the fluid aperture at a defined rate; measuring rate of change of impedance between the ablation and return electrodes during delivery of the RF current; and progressively adjusting the rate of delivery of the conductive fluid during delivery of the RF current in response to the measured rate of change of impedance between the ablation and return electrodes based upon a pre-determined correlation between fluid flow rate and impedance rate of change.
Claim 16
Independent Claim
139 words
A method of ablating a target tissue of a body of a patient, comprising: selecting a surgical instrument including an ablation electrode for delivery of RF current to the tissue and a fluid aperture for delivery of conductive fluid adjacent the ablation electrode; placing the ablation electrode adjacent the target tissue; delivering RF current between the ablation electrode and a return electrode; delivering the conductive fluid to the fluid aperture at a defined rate; measuring rate of change of impedance between the ablation and return electrodes during delivery of the RF current; and progressively adjusting the rate of delivery of the conductive fluid during delivery of the RF current in response to the measured rate of change of impedance between the ablation and return electrodes based upon a pre-determined correlation between fluid flow rate and impedance rate of change.
Claim 17
Dependent Claim
36 words
The method of claim 14 , wherein adjusting the rate of delivery of the conductive fluid comprises increasing fluid flow in response to an excessive rate of increase of impedance between the ablation and return electrodes.
Claim 18
Dependent Claim
22 words
The method of claim 14 or claim 15 , wherein delivering the conductive fluid comprises delivering the conductive fluid using a pump.
Claim 19
Dependent Claim
15 words
The method of claim 14 or claim 15 , wherein the conductive fluid is saline.
Claim 20
Dependent Claim
12 words
The method of claim 17 , wherein the saline is isotonic saline.
Claim 21
Dependent Claim
12 words
The method of claim 17 , wherein the saline is hypertonic saline.
Claim 22
Dependent Claim
17 words
The method of claim 14 or claim 15 , wherein the return electrode is a ground pad.
Claim 23
Dependent Claim
19 words
The method of claim 14 or claim 15 , wherein the return electrode is mounted to the surgical instrument.
Claim 24
Dependent Claim
19 words
The method of claim 14 or claim 15 , further comprising placing the return electrode adjacent the target tissue.
Claim 25
Dependent Claim
17 words
The method of claim 22 , further comprising delivery of the conductive fluid adjacent the return electrode.
Claim 26
Dependent Claim
24 words
The method of claim 14 or claim 15 , wherein measuring the rate of change of impedance comprises measuring impedances at predefined time intervals.
Claim 27
Independent Claim
172 words
A system for ablating a target tissue of a body of a patient, comprising: a surgical instrument including an ablation electrode for delivery of RF current to the tissue and a fluid aperture for delivery of conductive fluid adjacent the ablation electrode; a return electrode; an RF current generator coupled to the ablation and return electrodes to deliver RE current between the ablation and return electrodes; a fluid source coupled to the fluid aperture to deliver the conductive fluid to the fluid aperture at a defined rate; an impedance measurer coupled to the ablation and return electrodes to measure the impedance between the ablation and return electrodes during delivery of the RE current; and a fluid flow controller coupled to the fluid source and adapted to adjust the rate of delivery of the conductive fluid during delivery of the RF current, effecting an increase in the rate of delivery of the conductive fluid in response to a determined increase in measured impedance between the ablation and return electrodes above a pre-determined value.
Claim 28
Independent Claim
172 words
A system for ablating a target tissue of a body of a patient, comprising: a surgical instrument including an ablation electrode for delivery of RF current to the tissue and a fluid aperture for delivery of conductive fluid adjacent the ablation electrode; a return electrode; an RF current generator coupled to the ablation and return electrodes to deliver RE current between the ablation and return electrodes; a fluid source coupled to the fluid aperture to deliver the conductive fluid to the fluid aperture at a defined rate; an impedance measurer coupled to the ablation and return electrodes to measure the impedance between the ablation and return electrodes during delivery of the RE current; and a fluid flow controller coupled to the fluid source and adapted to adjust the rate of delivery of the conductive fluid during delivery of the RF current, effecting an increase in the rate of delivery of the conductive fluid in response to a determined increase in measured impedance between the ablation and return electrodes above a pre-determined value.
Claim 29
Dependent Claim
13 words
The system of claim 25 , wherein the fluid source comprises a pump.
Claim 30
Dependent Claim
13 words
The system of claim 25 , wherein the fluid source comprises a container.
Claim 31
Dependent Claim
12 words
The system of claim 25 , wherein the conductive fluid is saline.
Claim 32
Dependent Claim
12 words
The system of claim 28 , wherein the saline is isotonic saline.
Claim 33
Dependent Claim
12 words
The system of claim 28 , wherein the saline is hypertonic saline.
Claim 34
Dependent Claim
14 words
The system of claim 25 , wherein the return electrode is a ground pad.
Claim 35
Dependent Claim
16 words
The system of claim 25 , wherein the return electrode is mounted to the surgical instrument.
Claim 36
Dependent Claim
16 words
The system of claim 32 , wherein the return electrode serves as a second ablation electrode.
Claim 37
Dependent Claim
25 words
The system of claim 33 , wherein the surgical instrument further includes a fluid aperture for delivery of the conductive fluid adjacent the return electrode.
Claim 38
Dependent Claim
32 words
The system of claim 34 , wherein the surgical instrument further includes a fluid lumen in fluid communication with the fluid aperture for delivery of the conductive fluid adjacent the return electrode.
Claim 39
Dependent Claim
32 words
The system of claim 25 , wherein the surgical instrument further includes a fluid lumen in fluid communication with the fluid aperture for delivery of the conductive fluid adjacent the ablation electrode.
Claim 40
Dependent Claim
19 words
The system of claim 25 , wherein the impedance measurer includes means for measuring impedances at predefined time intervals.
Claim 41
Independent Claim
124 words
A method of ablating a target tissue of a body of a patient, comprising: selecting a surgical instrument including an ablation electrode for delivery of RF current to the tissue and a fluid aperture for delivery of conductive fluid adjacent the ablation electrode; placing the ablation electrode adjacent the target tissue; delivering RF current between the ablation electrode and a return electrode; delivering the conductive fluid to the fluid aperture at a defined rate; measuring impedance between the ablation and return electrodes during delivery of the RF current; and increasing the rate of delivery of the conductive fluid during delivery of the RF current, in response to a determined increase in the measured impedance between the ablation and return electrodes above a pre-determined value.
Claim 42
Independent Claim
124 words
A method of ablating a target tissue of a body of a patient, comprising: selecting a surgical instrument including an ablation electrode for delivery of RF current to the tissue and a fluid aperture for delivery of conductive fluid adjacent the ablation electrode; placing the ablation electrode adjacent the target tissue; delivering RF current between the ablation electrode and a return electrode; delivering the conductive fluid to the fluid aperture at a defined rate; measuring impedance between the ablation and return electrodes during delivery of the RF current; and increasing the rate of delivery of the conductive fluid during delivery of the RF current, in response to a determined increase in the measured impedance between the ablation and return electrodes above a pre-determined value.
Claim 43
Dependent Claim
19 words
The method of claim 38 , wherein delivering the conductive fluid comprises delivering the conductive fluid using a pump.
Claim 44
Dependent Claim
19 words
The method of claim 38 , wherein delivering the conductive fluid comprises delivering the conductive fluid from a container.
Claim 45
Dependent Claim
12 words
The method of claim 38 , wherein the conductive fluid is saline.
Claim 46
Dependent Claim
12 words
The method of claim 41 , wherein the saline is isotonic saline.
Claim 47
Dependent Claim
12 words
The method of claim 41 , wherein the saline is hypertonic saline.
Claim 48
Dependent Claim
14 words
The method of claim 38 , wherein the return electrode is a ground pad.
Claim 49
Dependent Claim
16 words
The method of claim 38 , wherein the return electrode is mounted to the surgical instrument.
Claim 50
Dependent Claim
16 words
The method of claim 38 , further comprising placing the return electrode adjacent the target tissue.
Claim 51
Dependent Claim
17 words
The method of claim 46 , further comprising delivery of the conductive fluid adjacent the return electrode.
Claim 52
Dependent Claim
16 words
The method of claim 38 , wherein measuring impedance comprises measuring impedances at predefined time intervals.
Claim 53
Independent Claim
159 words
A system for ablating a target tissue of a body of a patient, comprising: a surgical instrument including an ablation electrode for delivery of RF current to the tissue and a fluid delivery means adapted to interstitially infuse conductive fluid into the target tissue adjacent the ablation electrode; a return electrode; an RF current generator coupled to the ablation and return electrodes to deliver RF current between the ablation and return electrodes; a fluid source coupled to a fluid aperture to deliver the conductive fluid to the fluid aperture at a defined rate; an impedance measurer coupled to the ablation and return electrodes to measure impedance between the ablation and return electrodes during delivery of the RF current; and a fluid flow controller coupled to the fluid source adapted to adjust the rate of delivery of the conductive fluid to provide an increased rate of delivery in response to an increased measured impedance between the ablation and return electrodes.
Claim 54
Independent Claim
159 words
A system for ablating a target tissue of a body of a patient, comprising: a surgical instrument including an ablation electrode for delivery of RF current to the tissue and a fluid delivery means adapted to interstitially infuse conductive fluid into the target tissue adjacent the ablation electrode; a return electrode; an RF current generator coupled to the ablation and return electrodes to deliver RF current between the ablation and return electrodes; a fluid source coupled to a fluid aperture to deliver the conductive fluid to the fluid aperture at a defined rate; an impedance measurer coupled to the ablation and return electrodes to measure impedance between the ablation and return electrodes during delivery of the RF current; and a fluid flow controller coupled to the fluid source adapted to adjust the rate of delivery of the conductive fluid to provide an increased rate of delivery in response to an increased measured impedance between the ablation and return electrodes.
Claim 55
Dependent Claim
13 words
The system of claim 49 , wherein the fluid source comprises a pump.
Claim 56
Dependent Claim
13 words
The system of claim 49 , wherein the fluid source comprises a container.
Claim 57
Dependent Claim
12 words
The system of claim 49 , wherein the conductive fluid is saline.
Claim 58
Dependent Claim
12 words
The system of claim 52 , wherein the saline is isotonic saline.
Claim 59
Dependent Claim
12 words
The system of claim 52 , wherein the saline is hypertonic saline.
Claim 60
Dependent Claim
14 words
The system of claim 49 , wherein the return electrode is a ground pad.
Claim 61
Dependent Claim
16 words
The system of claim 49 , wherein the return electrode is mounted to the surgical instrument.
Claim 62
Dependent Claim
16 words
The system of claim 56 , wherein the return electrode serves as a second ablation electrode.
Claim 63
Dependent Claim
26 words
The system of claim 57 , wherein the surgical instrument further includes a second fluid aperture for delivery of the conductive fluid adjacent the return electrode.
Claim 64
Dependent Claim
34 words
The system of claim 58 , wherein the surgical instrument further includes a fluid lumen in fluid communication with the second fluid aperture for delivery of the conductive fluid adjacent to the return electrode.
Claim 65
Dependent Claim
32 words
The system of claim 49 , wherein the surgical instrument further includes a fluid lumen in fluid communication with the fluid aperture for delivery of the conductive fluid adjacent the ablation electrode.
Claim 66
Dependent Claim
19 words
The system of claim 49 , wherein the impedance measurer includes means for measuring impedances at predefined time intervals.
Claim 67
Independent Claim
124 words
A method of ablating a target tissue of a body of a patient, comprising: selecting a surgical instrument including an ablation electrode for delivery of RF current to the tissue and a fluid aperture for delivery of conductive fluid adjacent the ablation electrode; placing the ablation electrode adjacent the target tissue; delivering RF current between the ablation electrode and a return electrode; delivering the conductive fluid into the target tissue interstices through the fluid aperture at a defined rate; measuring impedance between the ablation and return electrodes during delivery of the RF current; and increasing the rate of delivery of the conductive fluid during delivery of the RF current, in response to an increase in the measured impedance between the ablation and return electrodes.
Claim 68
Independent Claim
124 words
A method of ablating a target tissue of a body of a patient, comprising: selecting a surgical instrument including an ablation electrode for delivery of RF current to the tissue and a fluid aperture for delivery of conductive fluid adjacent the ablation electrode; placing the ablation electrode adjacent the target tissue; delivering RF current between the ablation electrode and a return electrode; delivering the conductive fluid into the target tissue interstices through the fluid aperture at a defined rate; measuring impedance between the ablation and return electrodes during delivery of the RF current; and increasing the rate of delivery of the conductive fluid during delivery of the RF current, in response to an increase in the measured impedance between the ablation and return electrodes.
Claim 69
Dependent Claim
19 words
The method of claim 62 , wherein delivering the conductive fluid comprises delivering the conductive fluid using a pump.
Claim 70
Dependent Claim
19 words
The method of claim 62 , wherein delivering the conductive fluid comprises delivering the conductive fluid from a container.
Claim 71
Dependent Claim
12 words
The method of claim 62 , wherein the conductive fluid is saline.
Claim 72
Dependent Claim
12 words
The method of claim 65 , wherein the saline is isotonic saline.
Claim 73
Dependent Claim
12 words
The method of claim 65 , wherein the saline is hypertonic saline.
Claim 74
Dependent Claim
14 words
The method of claim 62 , wherein the return electrode is a ground pad.
Claim 75
Dependent Claim
16 words
The method of claim 62 , wherein the return electrode is mounted to the surgical instrument.
Claim 76
Dependent Claim
16 words
The method of claim 62 , further comprising placing the return electrode adjacent the target tissue.
Claim 77
Dependent Claim
17 words
The method of claim 70 , further comprising delivery of the conductive fluid adjacent the return electrode.
Claim 78
Dependent Claim
16 words
The method of claim 62 , wherein measuring impedance comprises measuring impedances at predefined time intervals.
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