US20070270796A2 - Radio frequency lasso - Google Patents
Radio frequency lasso Download PDFInfo
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- US20070270796A2 US20070270796A2 US11/282,928 US28292805A US2007270796A2 US 20070270796 A2 US20070270796 A2 US 20070270796A2 US 28292805 A US28292805 A US 28292805A US 2007270796 A2 US2007270796 A2 US 2007270796A2
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Classifications
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- A61B18/00—Surgical instruments, devices or methods for transferring non-mechanical forms of energy to or from the body
- A61B18/04—Surgical instruments, devices or methods for transferring non-mechanical forms of energy to or from the body by heating
- A61B18/12—Surgical instruments, devices or methods for transferring non-mechanical forms of energy to or from the body by heating by passing a current through the tissue to be heated, e.g. high-frequency current
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- A61B18/12—Surgical instruments, devices or methods for transferring non-mechanical forms of energy to or from the body by heating by passing a current through the tissue to be heated, e.g. high-frequency current
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Definitions
- the field of the application relates to medical devices, and more particularly, to systems and methods for cutting and/or ablating tissue.
- Tissue may be destroyed, ablated, or otherwise treated using thermal energy during various therapeutic procedures.
- Many forms of thermal energy may be imparted to tissue, such as radio frequency electrical energy, microwave electromagnetic energy, laser energy, acoustic energy, or thermal conduction.
- radio frequency ablation may be used to treat patients with tissue anomalies, such as liver anomalies and many primary cancers, such as cancers of the stomach, bowel, pancreas, kidney and lung.
- RFA treatment involves the destroying undesirable cells by generating heat through agitation caused by the application of alternating electrical current (radio frequency energy) through the tissue.
- U.S. Pat. No. 5,855,576 describes an ablation apparatus that includes a plurality of wire electrodes deployable from a cannula or catheter.
- Each of the wires includes a proximal end that is coupled to a generator, and a distal end that may project from a distal end of the cannula.
- the wires are arranged in an array with the distal ends located generally radially and uniformly spaced apart from the catheter distal end.
- the wires may be energized in a monopolar or bipolar configuration to heat and necrose tissue within a precisely defined volumetric region of target tissue.
- the current may flow between closely spaced wire electrodes (bipolar mode) or between one or more wire electrodes and a larger, common electrode (monopolar mode) located remotely from the tissue to be heated.
- ablation therapy uses heat to kill tissue at a target site.
- the effective rate of tissue ablation is highly dependent on how much of the target tissue is heated to a therapeutic level.
- complete ablation of target tissue that is adjacent a vessel may be difficult or impossible to perform, since significant blood flow may draw the produced heat away from the vessel wall, resulting in incomplete necrosis of the tissue surrounding the vessel.
- This phenomenon which causes the tissue with greater blood flow to be heated less, and the tissue with lesser blood flow to be heated more, is known as the “heat sink” effect. It is believed that the heat sink effect is more pronounced for ablation of tissue adjacent large vessels that are more than 3 millimeters (mm) in diameter. Due to the increased vascularity of the liver, the heat sink effect may cause recurrence of liver tumors after a radio frequency ablation.
- a system for resecting tissue includes a loop structure configured for cutting tissue, at least a portion of the loop structure formed by an elongate structure having a first end and a second end, wherein a length of the loop structure is adjustable by positioning the first end relative to the second end, wherein a first portion of the loop structure comprises a first electrode, and a second portion of the loop structure comprises a second electrode.
- a method for resecting tissue using a loop structure formed by an elongate structure having a first end and a second end, wherein a length of the loop structure is adjustable by positioning the first end relative to the second end includes positioning the loop structure around a tissue structure, delivering electrical energy to a portion of the tissue structure using a circuit formed by respective first and second portions of the loop structure, and cutting the tissue structure portion by tightening the loop structure.
- a system for resecting tissue includes a loop structure configured for cutting tissue, the loop structure formed by an elongate structure having a first end and a second end, wherein a length of the loop structure is adjustable by positioning the first end relative to the second end, and a support structure coupled to a portion of the elongate structure and having a surface for contacting tissue.
- a method for resecting tissue using a loop structure formed by an elongate structure having a first end and a second end, wherein a length of the loop structure is adjustable by positioning the first end relative to the second end, the elongate structure coupled to a support structure that forms a part of the loop structure includes positioning the support structure under a tissue structure, positioning the elongate structure above the tissue structure, and reducing a length of the elongate structure that is in contact with the tissue structure to thereby cut the tissue structure.
- FIG. 1 illustrates a treatment system for treating tissue in accordance with some embodiments
- FIG. 2 illustrates a variation of the treatment system of FIG. 1 in accordance with other embodiments
- FIG. 3 illustrates a treatment system for treating tissue in accordance with other embodiments
- FIGS. 4A-4D illustrates a method of treating tissue using the treatment system of FIG. 1 in accordance with some embodiments
- FIG. 5 illustrates a treatment system for treating tissue in accordance with other embodiments, showing the treatment system having a support structure
- FIG. 6 illustrates a treatment system for treating tissue in accordance with other embodiments, showing the treatment system having a support structure and a plurality of electrodes on the support structure;
- FIG. 7 illustrates a treatment system for treating tissue in accordance with other embodiments, showing the treatment system having an imaging device
- FIGS. 8A-8D illustrates a method of treating tissue using the treatment system of FIG. 6 in accordance with some embodiments
- FIG. 9 illustrates a variation of the treatment system of FIG. 1 in accordance with other embodiments.
- FIG. 10 illustrates a cross section of a lasso in accordance with some embodiments.
- FIG. 1 illustrates a treatment system 10 in accordance with some embodiments.
- the treatment system 10 includes a source of energy 12 , e.g., a radio frequency (RF) generator, a loop structure 14 formed by an elongate structure 16 having a first end 18 and a second end 20 , a first set of electrodes 22 a - 22 e , and a second set of electrodes 24 a - 24 e .
- the treatment system 10 further includes a cable 52 for electrically coupling the electrodes 22 , 24 to energy source 12 .
- RF radio frequency
- the generator 12 is preferably capable of operating with a fixed or controlled voltage so that power and current diminish as impedance of the tissue being ablated increases. Exemplary generators are described in U.S. Pat. No. 6,080,149, the disclosure of which is expressly incorporated by reference herein.
- the preferred generator 12 may operate at relatively low fixed voltages, typically below one hundred fifty volts (150 V) peak-to-peak, and preferably between about fifty and one hundred volts (50-100 V).
- Such radio frequency generators are available from Boston Scientific Corporation, assignee of the present application, as well as from other commercial suppliers. It should be noted that the generator 12 is not limited to those that operate at the range of voltages discussed previously, and that generators capable of operating at other ranges of voltages may also be used.
- the electrodes 22 a - 22 e are electrically coupled to a first terminal of the energy source 12
- the electrodes 24 a - 24 e are electrically coupled to a second terminal of the energy source 12
- the first and second terminals of the energy source 12 are opposite terminals, thereby allowing the electrodes 22 , 24 to deliver energy in a bipolar mode.
- the electrodes 22 a - 22 e form a first pole of a circuit
- the electrodes 24 a - 24 e form a second pole of the circuit.
- the first terminal of the generator 12 may be coupled to a first control circuit (not shown) within the generator 12 , that is configured to control the electrodes 22 a - 22 e
- the second terminal of the generator 12 may be coupled to a second control circuit (not shown) within the generator 12 , that is configured to control the electrodes 24 a - 24 e
- each of the electrodes 22 a - 22 e in the first set, and each of the electrodes 24 a - 24 e in the second set can be coupled to a control circuit within the generator 12 .
- control circuits can be configured (e.g., programmed, or modified by a switch) during use, such that a physician can select which of the electrodes 22 a - 22 e and 24 a - 24 e to be used as active electrode(s) (forming the firs pole of a circuit), and which of the electrodes 22 a - 22 e and 24 a - 24 e to be used as return electrode(s) (forming the second pole of a circuit).
- a physician may select electrodes 22 a - 22 c to be active electrodes, and electrodes 22 d , 22 e , and 24 a - 24 c to be return electrodes.
- the treatment system 10 can include other numbers of sets of electrodes. Also, in other embodiments, instead of having five electrodes in each set, the treatment system 10 can include more or less than five electrodes in each set.
- the treatment system 10 can include one electrode 22 in a first set, and one electrode 24 in a second set, with the electrodes 22 , 24 being electrically insulated by an insulator 200 ( FIG. 2 ).
- Each of the electrodes 22 , 24 can have an elongate body, thereby extending along a substantial length of the loop structure 14 .
- each of the electrodes 22 , 24 can be made from a metal wire that is secured to the insulator 200 .
- each of the electrodes 22 , 24 can have a relatively short body, such as that shown in FIG. 1 .
- the electrodes 22 , 24 deliver ablation energy in a bipolar configuration.
- the treatment system 10 further includes a sheath 28 having a distal end 30 , a proximal end 32 , and a lumen 34 extending between the ends 30 , 32 .
- the sheath 28 can be made from a variety of materials, such as a polymer, a metal, or an alloy, and can be either rigid or flexible. As shown in the figure, at least a portion of the elongate member 16 extends through the lumen 34 of the sheath 28 .
- the loop structure 14 can be bent or stretched to a low profile, and be housed within the lumen 34 of the sheath.
- the loop structure 14 can then be deployed out of the lumen 34 of the sheath 28 .
- the sheath 28 has a cross sectional dimension that is small enough to allow the sheath 28 be used as a cannula.
- the sheath 28 can have other cross sectional dimensions.
- the sheath 28 can have a cross sectional dimension that allows it be used as a trocar in an open surgery.
- the sheath 28 is optional, and the treatment system 10 does not include the sheath 28 .
- the treatment system 10 also includes a hollow shaft 36 having a distal end 38 , a proximal end 40 , and a lumen 42 extending between the ends 38 , 40 .
- the shaft 36 can be made from a variety of materials, such as a polymer, a metal, or an alloy, and can be either rigid or flexible.
- At least a portion of the elongate structure 16 extends through the lumen 42 of the shaft 36 , with the first end 18 of the elongate structure 16 secured to a handle 50 .
- the treatment system 10 also includes a loop 26 secured to the second end 20 of the elongate structure 16 .
- the loop 26 is secured to the distal end 38 of the shaft 36 , e.g., via glue, an adhesive, or a securing device, such as a screw.
- the loop 26 is not secured to the distal end 38 , but is coupled to the distal end 38 .
- the loop 26 may be coupled to the distal end 38 by a frictional force or a bearing force.
- the first end 18 of the elongate structure 16 is inserted through the loop 26 , and through the lumen 42 of the shaft 36 , thereby forming the loop structure 14 .
- the length (and therefore, the size) of the loop structure 14 can be adjusted by positioning the first end 18 relative to the second end 20 , or vice versa. Such can be accomplished by holding the handle 50 and the proximal end 40 of the shaft 36 , and moving the handle 50 relative to the proximal end 40 , or vice versa.
- the size of the loop structure 14 can be increased by advancing the handle 50 (and therefore, the first end 18 ) distally relative to the proximal end 40 (and therefore, the second end 20 ).
- the size of the loop structure 14 can be decreased by retracting the handle 50 proximally relative to the proximal end 40 .
- the treatment system 10 does not include the loop 26 .
- the second end 20 of the elongate member 16 is secured to the distal end 38 of the shaft 36 using, for example, a glue, an adhesive, or a securing device, such as a screw.
- the shaft 36 and the elongate structure 16 can be made from the same member. In such cases, a portion of the distal end 38 of the shaft 36 extends to form a portion of the second end 20 of the elongate structure 16 .
- the loop structure 14 can have different configurations.
- the loop structure 14 can be formed by inserting both ends 18 , 20 of the elongate member 16 through the shaft 36 ( FIG. 3 ).
- the length (and therefore, the size) of the loop structure 14 can be adjusted by positioning the first end 18 relative to the second end 20 , or vice versa.
- the size of the loop structure 14 can be increased by advancing the first end 18 (e.g., using the handle 50 ) distally relative to the second end 20 .
- the size of the loop structure 14 can be decreased by retracting the first end 18 proximally relative to the second end 20 .
- the loop structure 14 can have a feature that allows the loop structure 14 be used as a tissue cutting device.
- the loop structure 14 can have a cross sectional dimension that is sufficiently small (such as, less than 2 millimeters (mm), or more preferably, less than 1 mm) to allow the loop structure 14 to cut tissue.
- the loop structure 14 can include one or more cutting elements disposed on its surface, which allow the loop structure 14 be used to cut tissue.
- the cutting elements can be saw-teeth, diamond dusts.
- the loop structure 14 can have a cross section which is relatively flat, thereby biasing a cutting element to be in contact with a tissue surface.
- the loop structure 14 can have the cross sectional shape shown in FIG. 10 , which biases cutting element 302 to be in contact with tissue surface 304 .
- the cutting element 302 has a sharp end that can assist focusing energy (e.g., radio frequency energy) towards a direction, thereby providing an “edge effect.”
- the loop structure 14 has a size and/or cross sectional profile that does not allow the loop structure 14 to cut tissue.
- FIGS. 4A-4D illustrate a method of treating tissue using the treatment system 10 of FIG. 1 in accordance with some embodiments.
- the loop structure 14 is delivered to a target site, and the loop structure 14 is placed around a tissue 400 ( FIG. 4A ).
- Various techniques can be used to deliver the loop structure 14 to the target site.
- an incision is made on a patient's skin to create an opening.
- the loop structure 14 is then inserted through the opening percutaneously.
- the sheath 28 can be inserted partially through the skin opening, and the loop structure 14 is then inserted into the lumen 34 of the sheath 28 to gain access to the target site.
- the distal end 38 of the shaft 36 can be inserted into a vessel, and is then steered to the target site.
- the treatment system 10 can further include a steering mechanism for steering the distal end 38 of the shaft 36 .
- the treatment system 10 can include one or more steering wires that are secured to the distal end 38 .
- the treatment system 10 can include a guidewire for steering the distal end 38 .
- Steering mechanisms are well known in the art, and therefore, would not be described in detail.
- the distal end 38 of the shaft 36 can have a sharp tip for allowing the distal end 38 to puncture a vessel. Such configuration allows the distal end 38 to reach target tissue that is outside a vessel.
- the loop structure 14 (or the elongate structure 16 ) is housed within the lumen 42 of the shaft 36 , and is bent or stretched to a low profile.
- the elongate structure 16 which forms the loop structure 14 is stretched to have a profile that resembles the profile of the shaft 36 .
- the loop structure 14 may or may not have a loop configuration when confined within the lumen 42 of the shaft 36 .
- the first end 18 of the elongate structure 16 is advanced distally to thereby deploy the elongate structure 16 out of the distal end 38 of the shaft 42 , placing the loop structure 14 adjacent the tissue 400 to be treated.
- the loop structure 14 is placed around the tissue 400 .
- the first end 18 is then retracted proximally relative to the second end 20 to tighten the loop structure 14 around the tissue 400 .
- the electrodes 22 , 24 are placed against surface of the tissue 400 .
- energy preferably RF electrical energy
- the generator 12 may deliver energy to the second set of electrodes 24 , with the first set of electrodes 22 functioning as return electrodes.
- using the loop structure 14 to perform ablation allows most, if not all, of the cross section of the tissue 400 to be ablated. In some cases, the ablation causes blood within the ablated tissue to coagulate.
- part of the tissue 400 on one side of the ablation plane can be surgically removed (resect).
- the loop structure 14 is capable of cutting tissue, such can be accomplished by retracting the first end 18 of the elongate member 16 proximally relative to the second end 20 to thereby reduce a size of the loop structure 14 ( FIG. 4C ). As the size of the loop structure 14 decreases, the loop structure 14 cuts into the tissue. The first end 18 of the elongate member 16 is continued to be positioned proximally relative to the second end 20 until the entire cross section of the tissue 400 is cut ( FIG. 4D ).
- the loop structure 14 can be removed from the tissue 400 , and a separate surgical device can be used to cut the tissue 400 . As shown in the embodiments, because the lesion 402 is formed substantially across the entire cross section of the tissue 400 , there is no or little bleeding as the tissue 400 is being cut.
- the ablation of the tissue 400 and the cutting of the tissue 400 can be performed simultaneously.
- the electrodes 22 , 24 are used to deliver ablation energy to ablate the tissue 400 , while the first end 18 is positioned relative to the second end 20 to reduce the size of the loop structure 14 to cut the tissue 400 that is being ablated.
- the ablation of the tissue 400 can be performed in a series of steps. In such cases, the size of the loop structure 14 is progressively reduced after each step of the ablation. For example, tissue adjacent surface of organ 400 can be initially ablated first, and is then cut using the loop structure 14 . Additional tissue further below the surface of the organ 400 is then ablated, and is cut using the loop structure 14 after the ablation. Such is repeated until a resection is made across an entire cross section of the organ 400 .
- the treatment system 10 (or another ablation device/system) can be used to ablate a target treatment site (e.g., a tumor) located on one side of the lesion 402 .
- a target treatment site e.g., a tumor
- the formed lesion 402 can be used as a barrier to prevent or reduce blood from flowing from one side of the lesion 402 to the other side of the lesion 402 , thereby allowing the target treatment site located on one side of the lesion 402 to be ablated efficiently without being affected by a heat sink effect due to blood flow.
- the loop structure 14 can be tightened around the tissue 400 to compress a cross section, thereby preventing or reducing blood flow across the cross section of the tissue 400 .
- the treatment system 10 can further include a support structure 500 ( FIG. 5 ).
- the support structure 500 is placed against tissue surface on one side of the tissue, and supports the tissue while the loop structure 14 is used to cut the tissue from another side of the tissue.
- the support structure 500 is sized and/or shaped such that it does not cut through tissue.
- the support structure 500 includes a first end 502 , a second end 504 , and a lumen 506 extending between the ends 502 , 504 .
- a portion of the loop structure 14 is housed within the lumen 506 of the support structure 500 .
- the support structure 500 does not have the lumen 506 .
- the support structure 500 can include one or more anchoring elements disposed on a surface of the support structure 500 .
- the anchoring element(s) pierces into tissue to thereby prevent the support structure 500 from sliding relative to a tissue surface.
- the anchoring element can be a pin, a hook, or any of other devices that can penetrate into tissue.
- the support structure 500 can carry one or more electrodes 24 ( FIG. 6 ).
- the electrode(s) 24 can be used to perform ablation.
- the electrode(s) 24 can be used as sensing electrode(s) to sense a characteristic of tissue (e.g., temperature, impedance, etc.).
- any of the embodiments of the support structure 500 described herein can further include an imaging device 700 ( FIG. 7 ).
- the imaging device 700 can be an ultrasound imager or any of the imaging devices known in the art.
- the imaging device 700 can be coupled to a processor 702 (such as a computer), which processes image data obtained by the imaging device 700 , and generates graphics on a display 704 based on a result of the processing of the image data.
- the generated graphics allow a physician to visualize tissue that is being imaged by the imaging device 700 .
- FIGS. 8A-8D illustrate a method of treating tissue using the treatment system 10 of FIG. 6 in accordance with some embodiments.
- the loop structure 14 is delivered to a target site, and the loop structure 14 is placed around a tissue 800 ( FIG. 8A ).
- Various techniques can be used to deliver the loop structure 14 to the target site.
- an incision is made on a patient's skin to create an opening.
- the loop structure 14 is then inserted through the opening percutaneously.
- the sheath 28 can be inserted partially through the skin opening, and the loop structure 14 is then inserted into the lumen 34 of the sheath 28 to gain access to the target site.
- the distal end 38 of the shaft 36 can be inserted into a vessel, and is then steered to the target site.
- the treatment system 10 can further include a steering mechanism for steering the distal end 38 of the shaft 36 .
- the treatment system 10 can include one or more steering wires that are secured to the distal end 38 .
- the treatment system 10 can include a guidewire for steering the distal end 38 .
- Steering mechanisms are well known in the art, and therefore, would not be described in detail.
- the distal end 38 of the shaft 36 can have a sharp tip for allowing the distal end 38 to puncture a vessel. Such configuration allows the distal end 38 to reach target tissue that is outside a vessel.
- the loop structure 14 (or the elongate structure 16 ) and the support structure 500 are housed within the lumen 42 of the shaft 36 .
- the elongate structure 16 which forms the loop structure 14 is stretched to have a profile that resembles the profile of the shaft 36 .
- the loop structure 14 may or may not have a loop configuration when confined within the lumen 42 of the shaft 36 .
- the support structure 500 may have a bent, compressed, or folded configuration when housed within the lumen 42 of the shaft 36 .
- the support structure 500 is made from a rigid material and is not foldable, the support structure 500 can be made sufficiently small such that it can be housed within the lumen 42 .
- the first end 18 of the elongate structure 16 is advanced distally to thereby deploy the elongate structure 16 out of the distal end 38 of the shaft 42 , placing the loop structure 14 adjacent tissue 800 to be treated.
- the loop structure 14 is placed around the tissue 800 .
- the first end 18 is then retracted proximally relative to the second end 20 to tighten the loop structure 14 around the tissue 800 .
- the electrodes 22 , 24 are placed against surface of the tissue 800 .
- the imaging device 700 can be used to obtain an image of a portion of the tissue 800 (e.g., to confirm placement of the loop structure 14 , and/or location of target treatment area).
- energy preferably RF electrical energy
- the generator 12 may deliver energy to the second set of electrodes 24 , with the first set of electrodes 22 functioning as return electrodes.
- using the loop structure 14 to perform ablation allows most, if not all, of the cross section of the tissue 800 to be ablated.
- part of the tissue 800 on one side of the ablation plane can be surgically removed (resect).
- resect can be accomplished by retracting the first end 18 of the elongate member 16 proximally relative to the second end 20 to thereby reduce a size of the loop structure 14 ( FIG. 8C ).
- the loop structure 14 cuts into the tissue 800 .
- the first end 18 of the elongate member 16 is continued to be positioned proximally relative to the second end 20 until the entire cross section of the tissue 800 is cut ( FIG. 8D ).
- the support structure 500 contacts a surface of the tissue 800 on one side 810 of the tissue 800 , and does not cut through the tissue 800 from the side 810 .
- the cutting portion of the loop structure 14 is biased to cut into the tissue 800 from side 812 of the tissue 800 .
- the support structure 500 is placed on a bottom of the tissue 800 , thereby allowing a physician to visualize the top of the tissue 800 as the loop structure 14 is used to cut into the tissue 800 from the top side.
- the lesion 802 is formed substantially across the entire cross section of the tissue 800 , there is no or little bleeding as the tissue 400 is being cut.
- the ablation of the tissue 800 and the cutting of the tissue 800 can be performed simultaneously.
- the electrodes 22 , 24 are used to deliver ablation energy to ablate the tissue 800 , while the first end 18 is positioned relative to the second end 20 to reduce the size of the loop structure 14 to cut the tissue 800 that is being ablated.
- the ablation of the tissue 800 can be performed in a series of steps. In such cases, the size of the loop structure 14 is progressively reduced after each step of the ablation. For example, tissue adjacent surface of organ 800 can be initially ablated first, and is then cut using the loop structure 14 . Additional tissue further below the surface of the organ 800 is then ablated, and is cut using the loop structure 14 after the ablation. Such is repeated until a resection is made across an entire cross section of the organ 800 .
- the treatment system 10 (or another ablation device/system) can be used to ablate a target treatment site (e.g., a tumor) located on one side of the lesion 802 .
- a target treatment site e.g., a tumor
- the formed lesion 802 can be used as a barrier to prevent or reduce blood from flowing from one side of the lesion 802 to the other side of the lesion 802 , thereby allowing the target treatment site located on one side of the lesion 802 to be ablated efficiently without being affected by a heat sink effect due to blood flow.
- the electrodes 22 , 24 are used to perform tissue ablation in a bipolar configuration.
- the electrodes 22 , 24 can be used to perform tissue ablation in a monopolar configuration.
- the electrodes 22 , 24 may be connected to an active terminal of the generator 12 , and a common ground pad electrode (not shown) is electrically coupled to a return terminal of the generator 12 .
- the electrodes 22 , 24 then deliver energy to the common ground pad electrode, which is generally placed on a patient's skin, in a monopolar mode.
- the treatment system 10 may not include the electrodes 22 , 24 and the energy source 12 .
- the system 10 of FIG. 5 does not include the electrodes 22 , 24 . In such cases, the system 10 is only used to perform cutting or compressing of tissue.
- the treatment system 10 can further include a positioner 900 coupled to the elongate structure 16 ( FIG. 9 ).
- the elongate structure 16 has a plurality of teeth 902 , which allows a gear 904 driven by a motor 905 in the positioner 900 to position the elongate structure 16 relative to the shaft 36 .
- the positioner 900 further includes a processor 906 , and a signal wire 908 for supplying signals from a sensing electrode (not shown) on the loop structure 14 to the processor 906 .
- the sensing electrode senses a characteristic, such as temperature or impedance, of tissue being ablated, and the wire 908 transmits a signal associated with the sensed characteristic to the processor 906 .
- the processor 906 actuates the motor 905 to cause the gear 904 to turn in response to the signal received from the sensing electrode, thereby positioning the elongate structure 16 relative to the shaft 36 .
- the received signal indicates that tissue in contact with the sensing electrode has been desirably ablated.
- the processor 906 can be configured to compare the received signal (e.g., impedance) with a prescribed value, and determine that the tissue has been desirably ablated if the signal exceeds the prescribed value. In such cases, the positioner 900 will causes the shaft 16 to move proximately relative to the shaft 36 by a prescribed increment, thereby reducing the size of the loop of the loop structure 14 to cut tissue. The ablation procedure is then repeated to ablate additional tissue.
- the processor 906 again causes the dimension of the loop structure 14 to further reduce, thereby further cutting into the tissue that has been ablated. The above is repeated until the entire target tissue has been cut by the loop structure 14 .
- unit 900 is an instruction device that includes a signaling device (not shown), such as an alarm or a LED light.
- the instruction device 900 does not include the gear 904 .
- the processor 906 receives signal from the sensing electrode, and activates the signaling device when the signal indicates that tissue in contact with the sensing electrode has been desirably ablated.
- the processor 906 activates the signaling device to emit an audio signal, thereby instructing a physician to position the handle 50 proximately by a prescribed increment.
- the loop size of the loop structure 14 is reduced to cause the loop structure 14 to cut into tissue.
- the ablation procedure is then repeated to ablate additional tissue. The above is repeated until the entire target tissue has been cut by the loop structure 14 .
- the treatment system 10 is not necessarily limited to the configurations described previously, and that the treatment system 10 can have other configurations in other embodiments.
- the electrode(s) 22 and the electrode(s) 24 can have different shapes and/or sizes.
- the treatment system 10 instead of having the electrodes 22 , 24 for delivering RF energy, can include other types of energy delivering devices.
- the treatment system 10 can include one or more ultrasound transducers (for generating ultrasound energy), or one or more microwave energy generators (for generating microwave energy), that are located on, or form part of, the loop structure 14 .
- the treatment system 10 can be used to resect tissue from within the tissue.
- the distal end 38 can be placed adjacent to tissue surface, and the loop structure 14 is then deployed out of the distal end 38 to cut into tissue.
- the loop structure 14 is made from a relatively rigid material that allows the loop structure 14 to cut into tissue as the loop structure 14 is deployed out from the distal end 38 .
Abstract
Description
- 1. Field
- The field of the application relates to medical devices, and more particularly, to systems and methods for cutting and/or ablating tissue.
- 2. Background
- Tissue may be destroyed, ablated, or otherwise treated using thermal energy during various therapeutic procedures. Many forms of thermal energy may be imparted to tissue, such as radio frequency electrical energy, microwave electromagnetic energy, laser energy, acoustic energy, or thermal conduction.
- In particular, radio frequency ablation (RFA) may be used to treat patients with tissue anomalies, such as liver anomalies and many primary cancers, such as cancers of the stomach, bowel, pancreas, kidney and lung. RFA treatment involves the destroying undesirable cells by generating heat through agitation caused by the application of alternating electrical current (radio frequency energy) through the tissue.
- Various RF ablation devices have been suggested for this purpose. For example, U.S. Pat. No. 5,855,576 describes an ablation apparatus that includes a plurality of wire electrodes deployable from a cannula or catheter. Each of the wires includes a proximal end that is coupled to a generator, and a distal end that may project from a distal end of the cannula. The wires are arranged in an array with the distal ends located generally radially and uniformly spaced apart from the catheter distal end. The wires may be energized in a monopolar or bipolar configuration to heat and necrose tissue within a precisely defined volumetric region of target tissue. The current may flow between closely spaced wire electrodes (bipolar mode) or between one or more wire electrodes and a larger, common electrode (monopolar mode) located remotely from the tissue to be heated.
- Generally, ablation therapy uses heat to kill tissue at a target site. The effective rate of tissue ablation is highly dependent on how much of the target tissue is heated to a therapeutic level. In certain situations, complete ablation of target tissue that is adjacent a vessel may be difficult or impossible to perform, since significant blood flow may draw the produced heat away from the vessel wall, resulting in incomplete necrosis of the tissue surrounding the vessel. This phenomenon, which causes the tissue with greater blood flow to be heated less, and the tissue with lesser blood flow to be heated more, is known as the “heat sink” effect. It is believed that the heat sink effect is more pronounced for ablation of tissue adjacent large vessels that are more than 3 millimeters (mm) in diameter. Due to the increased vascularity of the liver, the heat sink effect may cause recurrence of liver tumors after a radio frequency ablation.
- Also, because of the vascularity of the liver, resection of a portion of a liver (as is required by some surgeries) may result in significant bleeding. Existing techniques in managing bleeding of a resected liver include delivering embolic material within a vessel of a liver to prevent blood flow. However, such technique is time consuming, may require complex imaging modality, and may not be effective in the case in which a relatively large portion of a liver is being resected.
- In accordance with some embodiments, a system for resecting tissue includes a loop structure configured for cutting tissue, at least a portion of the loop structure formed by an elongate structure having a first end and a second end, wherein a length of the loop structure is adjustable by positioning the first end relative to the second end, wherein a first portion of the loop structure comprises a first electrode, and a second portion of the loop structure comprises a second electrode.
- In accordance with other embodiments, a method for resecting tissue using a loop structure formed by an elongate structure having a first end and a second end, wherein a length of the loop structure is adjustable by positioning the first end relative to the second end, the method includes positioning the loop structure around a tissue structure, delivering electrical energy to a portion of the tissue structure using a circuit formed by respective first and second portions of the loop structure, and cutting the tissue structure portion by tightening the loop structure.
- In accordance with other embodiments, a system for resecting tissue includes a loop structure configured for cutting tissue, the loop structure formed by an elongate structure having a first end and a second end, wherein a length of the loop structure is adjustable by positioning the first end relative to the second end, and a support structure coupled to a portion of the elongate structure and having a surface for contacting tissue.
- In accordance with other embodiments, a method for resecting tissue using a loop structure formed by an elongate structure having a first end and a second end, wherein a length of the loop structure is adjustable by positioning the first end relative to the second end, the elongate structure coupled to a support structure that forms a part of the loop structure, the method includes positioning the support structure under a tissue structure, positioning the elongate structure above the tissue structure, and reducing a length of the elongate structure that is in contact with the tissue structure to thereby cut the tissue structure.
- Other aspects and features of the embodiments will be evident from reading the following description of the embodiments.
- The drawings illustrate the design and utility of embodiments of the application, in which similar elements are referred to by common reference numerals. In order to better appreciate how advantages and objects of various embodiments are obtained, a more particular description of the embodiments are illustrated in the accompanying drawings. Understanding that these drawings depict only typical embodiments of the application and are not therefore to be considered limiting its scope, the embodiments will be described and explained with additional specificity and detail through the use of the accompanying drawings.
-
FIG. 1 illustrates a treatment system for treating tissue in accordance with some embodiments; -
FIG. 2 illustrates a variation of the treatment system ofFIG. 1 in accordance with other embodiments; -
FIG. 3 illustrates a treatment system for treating tissue in accordance with other embodiments; -
FIGS. 4A-4D illustrates a method of treating tissue using the treatment system ofFIG. 1 in accordance with some embodiments; -
FIG. 5 illustrates a treatment system for treating tissue in accordance with other embodiments, showing the treatment system having a support structure; -
FIG. 6 illustrates a treatment system for treating tissue in accordance with other embodiments, showing the treatment system having a support structure and a plurality of electrodes on the support structure; -
FIG. 7 illustrates a treatment system for treating tissue in accordance with other embodiments, showing the treatment system having an imaging device; -
FIGS. 8A-8D illustrates a method of treating tissue using the treatment system ofFIG. 6 in accordance with some embodiments; -
FIG. 9 illustrates a variation of the treatment system ofFIG. 1 in accordance with other embodiments; and -
FIG. 10 illustrates a cross section of a lasso in accordance with some embodiments. -
FIG. 1 illustrates atreatment system 10 in accordance with some embodiments. Thetreatment system 10 includes a source ofenergy 12, e.g., a radio frequency (RF) generator, aloop structure 14 formed by anelongate structure 16 having afirst end 18 and asecond end 20, a first set ofelectrodes 22 a-22 e, and a second set ofelectrodes 24 a-24 e. Thetreatment system 10 further includes acable 52 for electrically coupling theelectrodes energy source 12. - The
generator 12 is preferably capable of operating with a fixed or controlled voltage so that power and current diminish as impedance of the tissue being ablated increases. Exemplary generators are described in U.S. Pat. No. 6,080,149, the disclosure of which is expressly incorporated by reference herein. Thepreferred generator 12 may operate at relatively low fixed voltages, typically below one hundred fifty volts (150 V) peak-to-peak, and preferably between about fifty and one hundred volts (50-100 V). Such radio frequency generators are available from Boston Scientific Corporation, assignee of the present application, as well as from other commercial suppliers. It should be noted that thegenerator 12 is not limited to those that operate at the range of voltages discussed previously, and that generators capable of operating at other ranges of voltages may also be used. - In the illustrated embodiments, the
electrodes 22 a-22 e are electrically coupled to a first terminal of theenergy source 12, and theelectrodes 24 a-24 e are electrically coupled to a second terminal of theenergy source 12. In some embodiments, the first and second terminals of theenergy source 12 are opposite terminals, thereby allowing theelectrodes electrodes 22 a-22 e form a first pole of a circuit, and theelectrodes 24 a-24 e form a second pole of the circuit. Also, in some embodiments, the first terminal of thegenerator 12 may be coupled to a first control circuit (not shown) within thegenerator 12, that is configured to control theelectrodes 22 a-22 e, and the second terminal of thegenerator 12 may be coupled to a second control circuit (not shown) within thegenerator 12, that is configured to control theelectrodes 24 a-24 e. In other embodiments, each of theelectrodes 22 a-22 e in the first set, and each of theelectrodes 24 a-24 e in the second set can be coupled to a control circuit within thegenerator 12. In such cases, the control circuits can be configured (e.g., programmed, or modified by a switch) during use, such that a physician can select which of theelectrodes 22 a-22 e and 24 a-24 e to be used as active electrode(s) (forming the firs pole of a circuit), and which of theelectrodes 22 a-22 e and 24 a-24 e to be used as return electrode(s) (forming the second pole of a circuit). For example, in some embodiments, a physician may selectelectrodes 22 a-22 c to be active electrodes, andelectrodes - Although two sets of
electrodes treatment system 10 can include other numbers of sets of electrodes. Also, in other embodiments, instead of having five electrodes in each set, thetreatment system 10 can include more or less than five electrodes in each set. For example, in some embodiments, thetreatment system 10 can include oneelectrode 22 in a first set, and oneelectrode 24 in a second set, with theelectrodes FIG. 2 ). Each of theelectrodes loop structure 14. For example, in some embodiments, each of theelectrodes insulator 200. Alternatively, each of theelectrodes FIG. 1 . Theelectrodes - In the illustrated embodiments, the
treatment system 10 further includes asheath 28 having adistal end 30, aproximal end 32, and alumen 34 extending between theends sheath 28 can be made from a variety of materials, such as a polymer, a metal, or an alloy, and can be either rigid or flexible. As shown in the figure, at least a portion of theelongate member 16 extends through thelumen 34 of thesheath 28. During use, theloop structure 14 can be bent or stretched to a low profile, and be housed within thelumen 34 of the sheath. When thedistal end 30 of thesheath 28 is positioned at a desired location (e.g., a treatment site), theloop structure 14 can then be deployed out of thelumen 34 of thesheath 28. In some embodiments, thesheath 28 has a cross sectional dimension that is small enough to allow thesheath 28 be used as a cannula. Alternatively, thesheath 28 can have other cross sectional dimensions. For example, thesheath 28 can have a cross sectional dimension that allows it be used as a trocar in an open surgery. In other embodiments, thesheath 28 is optional, and thetreatment system 10 does not include thesheath 28. - As shown in
FIG. 1 , thetreatment system 10 also includes ahollow shaft 36 having adistal end 38, aproximal end 40, and alumen 42 extending between theends shaft 36 can be made from a variety of materials, such as a polymer, a metal, or an alloy, and can be either rigid or flexible. At least a portion of theelongate structure 16 extends through thelumen 42 of theshaft 36, with thefirst end 18 of theelongate structure 16 secured to ahandle 50. Thetreatment system 10 also includes aloop 26 secured to thesecond end 20 of theelongate structure 16. In some embodiments, theloop 26 is secured to thedistal end 38 of theshaft 36, e.g., via glue, an adhesive, or a securing device, such as a screw. In other embodiments, theloop 26 is not secured to thedistal end 38, but is coupled to thedistal end 38. For example, theloop 26 may be coupled to thedistal end 38 by a frictional force or a bearing force. - As shown in the figure, the
first end 18 of theelongate structure 16 is inserted through theloop 26, and through thelumen 42 of theshaft 36, thereby forming theloop structure 14. The length (and therefore, the size) of theloop structure 14 can be adjusted by positioning thefirst end 18 relative to thesecond end 20, or vice versa. Such can be accomplished by holding thehandle 50 and theproximal end 40 of theshaft 36, and moving thehandle 50 relative to theproximal end 40, or vice versa. In some cases, the size of theloop structure 14 can be increased by advancing the handle 50 (and therefore, the first end 18) distally relative to the proximal end 40 (and therefore, the second end 20). Alternatively, the size of theloop structure 14 can be decreased by retracting thehandle 50 proximally relative to theproximal end 40. - In other embodiments, the
treatment system 10 does not include theloop 26. In such cases, thesecond end 20 of theelongate member 16 is secured to thedistal end 38 of theshaft 36 using, for example, a glue, an adhesive, or a securing device, such as a screw. In further embodiments, theshaft 36 and theelongate structure 16 can be made from the same member. In such cases, a portion of thedistal end 38 of theshaft 36 extends to form a portion of thesecond end 20 of theelongate structure 16. - In other embodiments, the
loop structure 14 can have different configurations. For example, in other embodiments, theloop structure 14 can be formed by inserting both ends 18, 20 of theelongate member 16 through the shaft 36 (FIG. 3 ). The length (and therefore, the size) of theloop structure 14 can be adjusted by positioning thefirst end 18 relative to thesecond end 20, or vice versa. For example, the size of theloop structure 14 can be increased by advancing the first end 18 (e.g., using the handle 50) distally relative to thesecond end 20. Alternatively, the size of theloop structure 14 can be decreased by retracting thefirst end 18 proximally relative to thesecond end 20. - In any of the embodiments of the
treatment system 10 described herein, theloop structure 14 can have a feature that allows theloop structure 14 be used as a tissue cutting device. For example, in some embodiments, theloop structure 14 can have a cross sectional dimension that is sufficiently small (such as, less than 2 millimeters (mm), or more preferably, less than 1 mm) to allow theloop structure 14 to cut tissue. In other embodiments, theloop structure 14 can include one or more cutting elements disposed on its surface, which allow theloop structure 14 be used to cut tissue. By means of non-limiting examples, the cutting elements can be saw-teeth, diamond dusts. In other embodiments, theloop structure 14 can have a cross section which is relatively flat, thereby biasing a cutting element to be in contact with a tissue surface. For example, theloop structure 14 can have the cross sectional shape shown inFIG. 10 , whichbiases cutting element 302 to be in contact withtissue surface 304. The cuttingelement 302 has a sharp end that can assist focusing energy (e.g., radio frequency energy) towards a direction, thereby providing an “edge effect.” In further embodiments, theloop structure 14 has a size and/or cross sectional profile that does not allow theloop structure 14 to cut tissue. -
FIGS. 4A-4D illustrate a method of treating tissue using thetreatment system 10 ofFIG. 1 in accordance with some embodiments. First, theloop structure 14 is delivered to a target site, and theloop structure 14 is placed around a tissue 400 (FIG. 4A ). - Various techniques can be used to deliver the
loop structure 14 to the target site. In some embodiments, an incision is made on a patient's skin to create an opening. Theloop structure 14 is then inserted through the opening percutaneously. In some cases, if thetreatment system 10 includes thesheath 28, thesheath 28 can be inserted partially through the skin opening, and theloop structure 14 is then inserted into thelumen 34 of thesheath 28 to gain access to the target site. Alternatively, thedistal end 38 of theshaft 36 can be inserted into a vessel, and is then steered to the target site. In such cases, thetreatment system 10 can further include a steering mechanism for steering thedistal end 38 of theshaft 36. For example, thetreatment system 10 can include one or more steering wires that are secured to thedistal end 38. Alternatively, thetreatment system 10 can include a guidewire for steering thedistal end 38. Steering mechanisms are well known in the art, and therefore, would not be described in detail. In some cases, thedistal end 38 of theshaft 36 can have a sharp tip for allowing thedistal end 38 to puncture a vessel. Such configuration allows thedistal end 38 to reach target tissue that is outside a vessel. - In the illustrated embodiments, before the
loop structure 14 is placed at the target site, the loop structure 14 (or the elongate structure 16) is housed within thelumen 42 of theshaft 36, and is bent or stretched to a low profile. In some embodiments, theelongate structure 16 which forms theloop structure 14 is stretched to have a profile that resembles the profile of theshaft 36. As such, theloop structure 14 may or may not have a loop configuration when confined within thelumen 42 of theshaft 36. After thedistal end 38 is positioned at a desired position, thefirst end 18 of theelongate structure 16 is advanced distally to thereby deploy theelongate structure 16 out of thedistal end 38 of theshaft 42, placing theloop structure 14 adjacent thetissue 400 to be treated. - As shown in
FIG. 4A , after theloop structure 14 is deployed or formed, theloop structure 14 is placed around thetissue 400. Thefirst end 18 is then retracted proximally relative to thesecond end 20 to tighten theloop structure 14 around thetissue 400. As a result, theelectrodes tissue 400. - Next, energy, preferably RF electrical energy, may be delivered from the
generator 12 to the first set ofelectrodes 22, with the second set ofelectrodes 24 functioning as return electrodes, thereby creating alesion 402 between the first andsecond electrodes 22, 24 (FIG. 4B ). Alternatively, thegenerator 12 may deliver energy to the second set ofelectrodes 24, with the first set ofelectrodes 22 functioning as return electrodes. In some embodiments, using theloop structure 14 to perform ablation allows most, if not all, of the cross section of thetissue 400 to be ablated. In some cases, the ablation causes blood within the ablated tissue to coagulate. - After a
lesion 402 across a substantial cross section of thetissue 400 has been created, part of thetissue 400 on one side of the ablation plane can be surgically removed (resect). In the illustrated embodiments, if theloop structure 14 is capable of cutting tissue, such can be accomplished by retracting thefirst end 18 of theelongate member 16 proximally relative to thesecond end 20 to thereby reduce a size of the loop structure 14 (FIG. 4C ). As the size of theloop structure 14 decreases, theloop structure 14 cuts into the tissue. Thefirst end 18 of theelongate member 16 is continued to be positioned proximally relative to thesecond end 20 until the entire cross section of thetissue 400 is cut (FIG. 4D ). Alternatively, if theloop structure 14 is not capable of cutting tissue, theloop structure 14 can be removed from thetissue 400, and a separate surgical device can be used to cut thetissue 400. As shown in the embodiments, because thelesion 402 is formed substantially across the entire cross section of thetissue 400, there is no or little bleeding as thetissue 400 is being cut. - In other embodiments, the ablation of the
tissue 400 and the cutting of thetissue 400 can be performed simultaneously. In such cases, theelectrodes tissue 400, while thefirst end 18 is positioned relative to thesecond end 20 to reduce the size of theloop structure 14 to cut thetissue 400 that is being ablated. In further embodiments, the ablation of thetissue 400 can be performed in a series of steps. In such cases, the size of theloop structure 14 is progressively reduced after each step of the ablation. For example, tissue adjacent surface oforgan 400 can be initially ablated first, and is then cut using theloop structure 14. Additional tissue further below the surface of theorgan 400 is then ablated, and is cut using theloop structure 14 after the ablation. Such is repeated until a resection is made across an entire cross section of theorgan 400. - In other embodiments, instead of cutting the
tissue 400, after thelesion 402 has been created, the treatment system 10 (or another ablation device/system) can be used to ablate a target treatment site (e.g., a tumor) located on one side of thelesion 402. In such cases, the formedlesion 402 can be used as a barrier to prevent or reduce blood from flowing from one side of thelesion 402 to the other side of thelesion 402, thereby allowing the target treatment site located on one side of thelesion 402 to be ablated efficiently without being affected by a heat sink effect due to blood flow. In some embodiments, theloop structure 14 can be tightened around thetissue 400 to compress a cross section, thereby preventing or reducing blood flow across the cross section of thetissue 400. - In any of the embodiments described herein, the
treatment system 10 can further include a support structure 500 (FIG. 5 ). During use, thesupport structure 500 is placed against tissue surface on one side of the tissue, and supports the tissue while theloop structure 14 is used to cut the tissue from another side of the tissue. As such, thesupport structure 500 is sized and/or shaped such that it does not cut through tissue. In the illustrated embodiments, thesupport structure 500 includes afirst end 502, asecond end 504, and alumen 506 extending between theends loop structure 14 is housed within thelumen 506 of thesupport structure 500. In other embodiments, thesupport structure 500 does not have thelumen 506. In such cases, a first portion of theelongate structure 16 is secured to one side of thesupport structure 500, and a second portion of theelongate structure 16 is secured to another side of thesupport structure 500, thereby allowing thesupport structure 500 to form a part of theloop structure 14. In further embodiments, thesupport structure 500 can include one or more anchoring elements disposed on a surface of thesupport structure 500. The anchoring element(s) pierces into tissue to thereby prevent thesupport structure 500 from sliding relative to a tissue surface. By means of non-limiting examples, the anchoring element can be a pin, a hook, or any of other devices that can penetrate into tissue. - In other embodiments, the
support structure 500 can carry one or more electrodes 24 (FIG. 6 ). The electrode(s) 24 can be used to perform ablation. Alternatively, the electrode(s) 24 can be used as sensing electrode(s) to sense a characteristic of tissue (e.g., temperature, impedance, etc.). - In further embodiments, any of the embodiments of the
support structure 500 described herein can further include an imaging device 700 (FIG. 7 ). Theimaging device 700 can be an ultrasound imager or any of the imaging devices known in the art. Theimaging device 700 can be coupled to a processor 702 (such as a computer), which processes image data obtained by theimaging device 700, and generates graphics on adisplay 704 based on a result of the processing of the image data. In some embodiments, the generated graphics allow a physician to visualize tissue that is being imaged by theimaging device 700. -
FIGS. 8A-8D illustrate a method of treating tissue using thetreatment system 10 ofFIG. 6 in accordance with some embodiments. First, theloop structure 14 is delivered to a target site, and theloop structure 14 is placed around a tissue 800 (FIG. 8A ). - Various techniques can be used to deliver the
loop structure 14 to the target site. In some embodiments, an incision is made on a patient's skin to create an opening. Theloop structure 14 is then inserted through the opening percutaneously. In some cases, if thetreatment system 10 includes thesheath 28, thesheath 28 can be inserted partially through the skin opening, and theloop structure 14 is then inserted into thelumen 34 of thesheath 28 to gain access to the target site. Alternatively, thedistal end 38 of theshaft 36 can be inserted into a vessel, and is then steered to the target site. In such cases, thetreatment system 10 can further include a steering mechanism for steering thedistal end 38 of theshaft 36. For example, thetreatment system 10 can include one or more steering wires that are secured to thedistal end 38. Alternatively, thetreatment system 10 can include a guidewire for steering thedistal end 38. Steering mechanisms are well known in the art, and therefore, would not be described in detail. In some cases, thedistal end 38 of theshaft 36 can have a sharp tip for allowing thedistal end 38 to puncture a vessel. Such configuration allows thedistal end 38 to reach target tissue that is outside a vessel. - In the illustrated embodiments, before the
loop structure 14 is placed at the target site, the loop structure 14 (or the elongate structure 16) and thesupport structure 500 are housed within thelumen 42 of theshaft 36. In some embodiments, theelongate structure 16 which forms theloop structure 14 is stretched to have a profile that resembles the profile of theshaft 36. As such, theloop structure 14 may or may not have a loop configuration when confined within thelumen 42 of theshaft 36. Also, thesupport structure 500 may have a bent, compressed, or folded configuration when housed within thelumen 42 of theshaft 36. Alternatively, if thesupport structure 500 is made from a rigid material and is not foldable, thesupport structure 500 can be made sufficiently small such that it can be housed within thelumen 42. After thedistal end 38 is positioned at a desired position. Thefirst end 18 of theelongate structure 16 is advanced distally to thereby deploy theelongate structure 16 out of thedistal end 38 of theshaft 42, placing theloop structure 14adjacent tissue 800 to be treated. - As shown in
FIG. 8A , after theloop structure 14 is deployed or formed, theloop structure 14 is placed around thetissue 800. Thefirst end 18 is then retracted proximally relative to thesecond end 20 to tighten theloop structure 14 around thetissue 800. As a result, theelectrodes tissue 800. In some embodiments, if thetreatment system 10 includes theimaging device 700, theimaging device 700 can be used to obtain an image of a portion of the tissue 800 (e.g., to confirm placement of theloop structure 14, and/or location of target treatment area). - Next, energy, preferably RF electrical energy, may be delivered from the
generator 12 to the first set ofelectrodes 22, with the second set ofelectrodes 24 functioning as return electrodes, thereby creating alesion 802 between the first andsecond electrodes 22, 24 (FIG. 8B ). Alternatively, thegenerator 12 may deliver energy to the second set ofelectrodes 24, with the first set ofelectrodes 22 functioning as return electrodes. In some embodiments, using theloop structure 14 to perform ablation allows most, if not all, of the cross section of thetissue 800 to be ablated. - After a lesion across a substantial cross section of the
tissue 800 has been created, part of thetissue 800 on one side of the ablation plane can be surgically removed (resect). In the illustrated embodiments, such can be accomplished by retracting thefirst end 18 of theelongate member 16 proximally relative to thesecond end 20 to thereby reduce a size of the loop structure 14 (FIG. 8C ). As the size of theloop structure 14 decreases, theloop structure 14 cuts into thetissue 800. Thefirst end 18 of theelongate member 16 is continued to be positioned proximally relative to thesecond end 20 until the entire cross section of thetissue 800 is cut (FIG. 8D ). As shown in the above embodiments, thesupport structure 500 contacts a surface of thetissue 800 on oneside 810 of thetissue 800, and does not cut through thetissue 800 from theside 810. As a result, the cutting portion of theloop structure 14 is biased to cut into thetissue 800 fromside 812 of thetissue 800. In some embodiments, thesupport structure 500 is placed on a bottom of thetissue 800, thereby allowing a physician to visualize the top of thetissue 800 as theloop structure 14 is used to cut into thetissue 800 from the top side. Also, as shown in the embodiments, because thelesion 802 is formed substantially across the entire cross section of thetissue 800, there is no or little bleeding as thetissue 400 is being cut. - In other embodiments, the ablation of the
tissue 800 and the cutting of thetissue 800 can be performed simultaneously. In such cases, theelectrodes tissue 800, while thefirst end 18 is positioned relative to thesecond end 20 to reduce the size of theloop structure 14 to cut thetissue 800 that is being ablated. In further embodiments, the ablation of thetissue 800 can be performed in a series of steps. In such cases, the size of theloop structure 14 is progressively reduced after each step of the ablation. For example, tissue adjacent surface oforgan 800 can be initially ablated first, and is then cut using theloop structure 14. Additional tissue further below the surface of theorgan 800 is then ablated, and is cut using theloop structure 14 after the ablation. Such is repeated until a resection is made across an entire cross section of theorgan 800. - In other embodiments, instead of cutting the
tissue 800, after thelesion 802 has been created, the treatment system 10 (or another ablation device/system) can be used to ablate a target treatment site (e.g., a tumor) located on one side of thelesion 802. In such cases, the formedlesion 802 can be used as a barrier to prevent or reduce blood from flowing from one side of thelesion 802 to the other side of thelesion 802, thereby allowing the target treatment site located on one side of thelesion 802 to be ablated efficiently without being affected by a heat sink effect due to blood flow. - In the above embodiments, the
electrodes electrodes electrodes generator 12, and a common ground pad electrode (not shown) is electrically coupled to a return terminal of thegenerator 12. Theelectrodes - Also, in any of the embodiments described herein, the
treatment system 10 may not include theelectrodes energy source 12. For example, in other embodiments, thesystem 10 ofFIG. 5 , does not include theelectrodes system 10 is only used to perform cutting or compressing of tissue. - In any of the embodiments described herein, the
treatment system 10 can further include apositioner 900 coupled to the elongate structure 16 (FIG. 9 ). In such cases, theelongate structure 16 has a plurality ofteeth 902, which allows agear 904 driven by amotor 905 in thepositioner 900 to position theelongate structure 16 relative to theshaft 36. In the illustrated embodiments, thepositioner 900 further includes aprocessor 906, and asignal wire 908 for supplying signals from a sensing electrode (not shown) on theloop structure 14 to theprocessor 906. During use, the sensing electrode senses a characteristic, such as temperature or impedance, of tissue being ablated, and thewire 908 transmits a signal associated with the sensed characteristic to theprocessor 906. Theprocessor 906, in turn, actuates themotor 905 to cause thegear 904 to turn in response to the signal received from the sensing electrode, thereby positioning theelongate structure 16 relative to theshaft 36. - In some embodiments, the received signal indicates that tissue in contact with the sensing electrode has been desirably ablated. For example, the
processor 906 can be configured to compare the received signal (e.g., impedance) with a prescribed value, and determine that the tissue has been desirably ablated if the signal exceeds the prescribed value. In such cases, thepositioner 900 will causes theshaft 16 to move proximately relative to theshaft 36 by a prescribed increment, thereby reducing the size of the loop of theloop structure 14 to cut tissue. The ablation procedure is then repeated to ablate additional tissue. When the additional tissue is desirably ablated, as indicated by the impedance signal received by theprocessor 906, theprocessor 906 again causes the dimension of theloop structure 14 to further reduce, thereby further cutting into the tissue that has been ablated. The above is repeated until the entire target tissue has been cut by theloop structure 14. - In other embodiments, instead of having the
motor 905,unit 900 is an instruction device that includes a signaling device (not shown), such as an alarm or a LED light. In such cases, theinstruction device 900 does not include thegear 904. During use, theprocessor 906 receives signal from the sensing electrode, and activates the signaling device when the signal indicates that tissue in contact with the sensing electrode has been desirably ablated. For example, in the case of the signaling device being an alarm, theprocessor 906 activates the signaling device to emit an audio signal, thereby instructing a physician to position thehandle 50 proximately by a prescribed increment. As a result the loop size of theloop structure 14 is reduced to cause theloop structure 14 to cut into tissue. The ablation procedure is then repeated to ablate additional tissue. The above is repeated until the entire target tissue has been cut by theloop structure 14. - It should be noted that the
treatment system 10 is not necessarily limited to the configurations described previously, and that thetreatment system 10 can have other configurations in other embodiments. For example, in other embodiments, the electrode(s) 22 and the electrode(s) 24 can have different shapes and/or sizes. Also, in other embodiments, instead of having theelectrodes treatment system 10 can include other types of energy delivering devices. For example, in other embodiments, thetreatment system 10 can include one or more ultrasound transducers (for generating ultrasound energy), or one or more microwave energy generators (for generating microwave energy), that are located on, or form part of, theloop structure 14. - In any of the embodiments described herein, instead of looping around target tissue to cut tissue from its perimeter, the
treatment system 10 can be used to resect tissue from within the tissue. For example, thedistal end 38 can be placed adjacent to tissue surface, and theloop structure 14 is then deployed out of thedistal end 38 to cut into tissue. As theloop structure 14 is further deployed, it cut closer and closer to a tissue surface, until an entire cross section of the tissue is resect. In such cases, theloop structure 14 is made from a relatively rigid material that allows theloop structure 14 to cut into tissue as theloop structure 14 is deployed out from thedistal end 38. - Thus, although several embodiments have been shown and described, it would be apparent to those skilled in the art that many changes and modifications may be made thereunto without the departing from the scope of the invention, which is defined by the following claims and their equivalents.
Claims (36)
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PCT/US2006/060255 WO2007062280A2 (en) | 2005-11-18 | 2006-10-26 | Radio frequency lasso |
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US11/282,928 US9333026B2 (en) | 2005-11-18 | 2005-11-18 | Radio frequency lasso |
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Also Published As
Publication number | Publication date |
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WO2007062280A3 (en) | 2007-11-15 |
US20070118110A1 (en) | 2007-05-24 |
US9333026B2 (en) | 2016-05-10 |
WO2007062280A2 (en) | 2007-05-31 |
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