US20110098704A1 - Electrical ablation devices - Google Patents

Abstract

An electrical ablation apparatus comprises first and second electrodes. Each electrode comprises a first end configured to couple an energy source and a second end configured to couple to a tissue treatment region. An energy source is coupled to the first and second electrodes. At least one electrode is movable between a first position and a second position. A first necrotic zone having a first shape is created when the electrodes are energized in the first position and a second necrotic zone having a second shape is created when the electrodes are energized in the second position. At least one electrode may be pre-formed with a radius.

Description

BACKGROUND
• Electrical ablation therapy has been employed in medicine for the treatment of undesirable tissue such as diseased tissue, cancer, malignant and benign tumors, masses, lesions, and other abnormal tissue growths. While conventional apparatuses, systems, and methods for the electrical ablation of undesirable tissue are effective, one drawback with conventional electrical ablation treatment is the resulting permanent damage that may occur to the healthy tissue surrounding the abnormal tissue due primarily to the detrimental thermal effects resulting from exposing the tissue to thermal energy generated by the electrical ablation device. This may be particularly true when exposing the tissue to electric potentials sufficient to cause cell necrosis using high temperature thermal therapies including focused ultrasound ablation, radiofrequency (RF) ablation, or interstitial laser coagulation. Other techniques for tissue ablation include chemical ablation, in which chemical agents are injected into the undesirable tissue to cause ablation as well as surgical excision, cryotherapy, radiation, photodynamic therapy, Moh's micrographic surgery, topical treatments with 5-fluorouracil, laser ablation. Other drawbacks of conventional thermal, chemical, and other ablation therapy are cost, length of recovery, and the extraordinary pain inflicted on the patient.
• Conventional thermal, chemical, and other ablation techniques have been employed for the treatment of a variety of undesirable tissue. Thermal and chemical ablation techniques have been used for the treatment of varicose veins resulting from reflux disease of the greater saphenous vein (GSV), in which the varicose vein is stripped and then is exposed to either chemical or thermal ablation. Other techniques for the treatment of undesirable tissue are more radical. Prostate cancer, for example, may be removed using a prostatectomy, in which the entire or part of prostate gland and surrounding lymph nodes are surgically removed. Like most other forms of cancer, radiation therapy may be used in conjunction with or as an alternate method for the treatment of prostate cancer. Another thermal ablation technique for the treatment of prostate cancer is RF interstitial tumor ablation (RITA) via trans-rectal ultrasound guidance. While these conventional methods for the treatment of prostate cancer are effective, they are not preferred by many surgeons and may result in detrimental thermal effects to healthy tissue surrounding the prostate. Similar thermal ablation techniques may be used for the treatment of basal cell carcinoma (BCC) tissue, a slowly growing cutaneous malignancy derived from the rapidly proliferating basal layer of the epidermis. BCC tissue in tumors ranging in size from about 5 mm to about 40 mm may be thermally ablated with a pulsed carbon dioxide laser. Nevertheless, carbon dioxide laser ablation is a thermal treatment method and may cause permanent damage to healthy tissue surrounding the BCC tissue. Furthermore, this technique requires costly capital investment in carbon dioxide laser equipment. Undesirable tissue growing inside a body lumen such as the esophagus, large bowel, or in cavities formed in solid tissue such as the breast, for example, can be difficult to destroy using conventional ablation techniques. Surgical removal of undesirable tissue, such as a malignant or benign tumor, from the breast is likely to leave a cavity. Surgical resection of residual intralumenal tissue may remove only a portion of the undesirable tissue cells within a certain margin of healthy tissue. Accordingly, some undesirable tissue is likely to remain within the wall of the cavity due to the limitation of conventional ablation instrument configurations, which may be effective for treating line-of-sight regions of tissue, but may be less effective for treating the residual undesirable tissue.
• Accordingly, there remains a need for improved electrical ablation apparatuses, systems, and methods for the treatment of undesirable tissue found in diseased tissue, cancer, malignant and benign tumors, masses, lesions, and other abnormal tissue growths. There remains a need for minimally invasive treatment of undesirable tissue through the use of irreversible electroporation (IRE) ablation techniques without causing the detrimental thermal effects of conventional thermal ablation techniques.
FIGURES
• The novel features of the various described embodiments are set forth with particularity in the appended claims. The various embodiments, however, both as to organization and methods of operation, together with advantages thereof, may be understood in accordance with the following description taken in conjunction with the accompanying drawings as follows.
• FIG. 1 illustrates one embodiment of an electrical ablation system in accordance with one non-limiting embodiment.
• FIGS. 2A-D illustrate one embodiment of the electrical ablation device in various phases of deployment.
• FIGS. 3A-C illustrate perspective views of one embodiment of the electrical ablation device shown inFIGS. 2A-2D.
• FIGS. 4A-C illustrate perspective views of one embodiment of the electrical ablation device.
• FIGS. 5A-C illustrate the operation of electrical ablation device shown inFIGS. 4A-C in accordance with one non-limiting embodiment.
• FIG. 6 illustrates an electrical ablation apparatus in accordance with one non-limiting embodiment.
• FIG. 7 illustrates an electrical ablation apparatus in accordance with one non-limiting embodiment.
• FIG. 8 illustrates an electrical ablation apparatus in accordance with one non-limiting embodiment.
• FIG. 9 illustrates an electrical ablation apparatus in accordance with one non-limiting embodiment.
• FIG. 10 illustrates an electrical ablation apparatus in accordance with one non-limiting embodiment.
• FIGS. 11A-B illustrate the use of an alignment guide with an electrical ablation apparatus in accordance with one non-limiting embodiment.
• FIG. 12 illustrates the engagement of the alignment guide shown inFIGS. 11A-B and a handle of the electrical ablation apparatus shown inFIGS. 11A-B.
• FIG. 13 illustrates an alignment guide comprising a plurality of visual indicators in accordance with one non-limiting embodiment.
• FIG. 14 illustrates an alignment guide comprising a plurality of detents in accordance with one non-limiting embodiment.
DESCRIPTION
• Various embodiments are directed to apparatuses, systems, and methods for the electrical ablation treatment of undesirable tissue such as diseased tissue, cancer, malignant and benign tumors, masses, lesions, and other abnormal tissue growths without causing any detrimental thermal effects to surrounding healthy tissue. Numerous specific details are set forth to provide a thorough understanding of the overall structure, function, manufacture, and use of the embodiments as described in the specification and illustrated in the accompanying drawings. It will be understood by those skilled in the art, however, that the embodiments may be practiced without the specific details described and illustrated herein. In other instances, well-known operations, components, and elements have not been described in detail so as not to obscure the embodiments described in the specification. Those of ordinary skill in the art will understand that the embodiments described and illustrated herein are non-limiting examples, and thus it can be appreciated that the specific structural and functional details disclosed herein may be representative and do not necessarily limit the scope of the embodiments, the scope of which is defined solely by the appended claims.
• Reference throughout the specification to “various embodiments,” “some embodiments,” “one embodiment,” or “an embodiment” means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment. Thus, appearances of the phrases “in various embodiments,” “in some embodiments,” “in one embodiment,” or “in an embodiment” in places throughout the specification are not necessarily all referring to the same embodiment. Furthermore, the particular features, structures, or characteristics may be combined in any suitable manner in one or more embodiments. Thus, the particular features, structures, or characteristics illustrated or described in connection with one embodiment may be combined, in whole or in part, with the features structures, or characteristics of one or more other embodiments without limitation.
• It will be appreciated that the terms “proximal” and “distal” may be used throughout the specification with reference to a clinician manipulating one end of an instrument used to treat a patient. The term “proximal” refers to the portion of the instrument closest to the clinician and the term “distal” refers to the portion located furthest from the clinician. It will be further appreciated that for conciseness and clarity, spatial terms such as “vertical,” “horizontal,” “up,” and “down” may be used herein with respect to the illustrated embodiments. However, surgical instruments may be used in many orientations and positions, and these terms are not intended to be limiting and absolute.
• Various embodiments of apparatuses, systems, and methods for the electrical ablation treatment of undesirable tissue such as diseased tissue, cancer, malignant and benign tumors, masses, lesions, and other abnormal tissue growths, are described throughout the specification and illustrated in the accompanying drawings. The electrical ablation devices in accordance with the described embodiments may comprise one or more electrodes configured to be positioned into or proximal to undesirable tissue in a tissue treatment region (e.g., target site, worksite) where there is evidence of abnormal tissue growth, for example. In general, the electrodes comprise an electrically conductive portion (e.g., medical grade stainless steel, gold plated, etc.) and are configured to electrically couple to an energy source. Once the electrodes are positioned into or proximal to the undesirable tissue, an energizing potential is applied to the electrodes to create an electric field to which the undesirable tissue is exposed. The energizing potential (and the resulting electric field) may be characterized by multiple parameters such as frequency, amplitude, pulse width (duration of a pulse or pulse length), and/or polarity. Depending on the diagnostic or therapeutic treatment to be rendered, a particular electrode may be configured either as an anode (+) or a cathode (−) or may comprise a plurality of electrodes with at least one configured as an anode and at least one other configured as a cathode. Regardless of the initial polar configuration, the polarity of the electrodes may be reversed by reversing the polarity of the output of the energy source.
• In various embodiments, a suitable energy source may comprise an electrical waveform generator, which may be configured to create an electric field that is suitable to create irreversible electroporation in undesirable tissue at various electric field amplitudes and durations. The energy source may be configured to deliver irreversible electroporation pulses in the form of direct-current (DC) and/or alternating-current (AC) voltage potentials (e.g., time-varying voltage potentials) to the electrodes. The energy source may also be configured to reverse the potential between the electrodes. The irreversible electroporation pulses may be characterized by various parameters such as frequency, amplitude, pulse length, and/or polarity. The undesirable tissue may be ablated by exposure to the electric potential difference across the electrodes.
• In one embodiment, the energy source may comprise a wireless transmitter to deliver energy to the electrodes using wireless energy transfer techniques via one or more remotely positioned antennas. Those skilled in the art will appreciate that wireless energy transfer or wireless power transmission is the process of transmitting electrical energy from an energy source to an electrical load without interconnecting wires. An electrical transformer is the simplest instance of wireless energy transfer. The primary and secondary circuits of a transformer are not directly connected and the transfer of energy takes place by electromagnetic coupling through a process known as mutual induction. Power also may be transferred wirelessly using RF energy. Wireless power transfer technology using RF energy is produced by Powercast, Inc. and can achieve an output of about6 volts for a little over one meter. Other low-power wireless power technology has been proposed such as described in U.S. Pat. No. 6,967,462.
• The apparatuses, systems, and methods in accordance with the described embodiments may be configured for minimally invasive ablation treatment of undesirable tissue through the use of irreversible electroporation to be able to ablate undesirable tissue in a controlled and focused manner without inducing thermally damaging effects to the surrounding healthy tissue. The apparatuses, systems, and methods in accordance with the described embodiments may be configured to ablate undesirable tissue through the use of electroporation or electropermeabilization. More specifically, the apparatuses, systems, and methods in accordance with the described embodiments may be configured to ablate undesirable tissue through the use of irreversible electroporation. Electroporation increases the permeabilization of a cell membrane by exposing the cell to electric pulses. The external electric field (electric potential/per unit length) to which the cell membrane is exposed to significantly increases the electrical conductivity and permeability of the plasma in the cell membrane. The primary parameter affecting the transmembrane potential is the potential difference across the cell membrane. Irreversible electroporation is the application of an electric field of a specific magnitude and duration to a cell membrane such that the permeabilization of the cell membrane cannot be reversed, leading to cell death without inducing a significant amount of heat in the cell membrane. The destabilizing potential forms pores in the cell membrane when the potential across the cell membrane exceeds its dielectric strength causing the cell to die under a process known as apoptosis and/or necrosis. The application of irreversible electroporation pulses to cells is an effective way for ablating large volumes of undesirable tissue without deleterious thermal effects to the surrounding healthy tissue associated with thermal-inducing ablation treatments. This is because irreversible electroporation destroys cells without heat and thus does not destroy the cellular support structure or regional vasculature. A destabilizing irreversible electroporation pulse, suitable to cause cell death without inducing a significant amount of thermal damage to the surrounding healthy tissue, may have amplitude in the range of about several hundred to about several thousand volts and is generally applied across biological membranes over a distance of about several millimeters, for example, for a relatively long duration. Thus, the undesirable tissue may be ablated in-vivo through the delivery of destabilizing electric fields by quickly creating cell necrosis.
• The apparatuses, systems, and methods for electrical ablation therapy in accordance with the described embodiments may be adapted for use in minimally invasive surgical procedures to access the tissue treatment region in various anatomic locations such as the brain, lungs, breast, liver, gall bladder, pancreas, prostate gland, and various internal body lumen defined by the esophagus, stomach, intestine, colon, arteries, veins, anus, vagina, cervix, fallopian tubes, and the peritoneal cavity, for example, without limitation. Minimally invasive electrical ablation devices may be introduced to the tissue treatment region using a trocar inserted though a small opening formed in the patient's body or through a natural body orifice such as the mouth, anus, or vagina using translumenal access techniques known as Natural Orifice Translumenal Endoscopic Surgery (NOTES)™. Once the electrical ablation devices (e.g., electrodes) are located into or proximal to the undesirable tissue in the treatment region, electric field potentials can be applied to the undesirable tissue by the energy source. The electrical ablation devices comprise portions that may be inserted into the tissue treatment region percutaneously (e.g., where access to inner organs or other tissue is done via needle-puncture of the skin). Other portions of the electrical ablation devices may be introduced into the tissue treatment region endoscopically (e.g., laparoscopically and/or thoracoscopically) through trocars or channels of the endoscope, through small incisions, or transcutaneously (e.g., where electric pulses are delivered to the tissue treatment region through the skin). An electrical ablation device in commonly owned U.S. patent application Ser. No. 12/352,375 titled “ELECTRICAL ABLATION DEVICES,” filed Jan. 12, 2009, the entire disclosure of which is incorporated herein by reference in its entirety.
• FIG. 1 illustrates one embodiment of anelectrical ablation system10. Theelectrical ablation system10 may be employed to ablate undesirable tissue such as diseased tissues, cancers, tumors, masses, lesions, abnormal tissue growths inside a patient using electrical energy. Theelectrical ablation system10 may be used in conjunction with endoscopic, laparoscopic, thoracoscopic, open surgical procedures via small incisions or keyholes, percutaneous techniques, transcutaneous techniques, and/or external non-invasive techniques, or any combinations thereof without limitation. Theelectrical ablation system10 may be configured to be positioned within a natural body orifice of the patient such as the mouth, anus, or vagina and advanced through internal body lumen or cavities such as the esophagus, colon, cervix, urethra, for example, to reach the tissue treatment region. Theelectrical ablation system10 also may be configured to be positioned and passed through a small incision or keyhole formed through the skin or abdominal wall of the patient to reach the tissue treatment region using a trocar. The tissue treatment region may be located in the brain, lungs, breast, liver, gall bladder, pancreas, prostate gland, various internal body lumen defined by the esophagus, stomach, intestine, colon, arteries, veins, anus, vagina, cervix, fallopian tubes, and the peritoneal cavity, for example, without limitation. Theelectrical ablation system10 can be configured to treat a number of lesions and ostepathologies comprising metastatic lesions, tumors, fractures, infected sites, inflamed sites. Once positioned into or proximate the tissue treatment region, theelectrical ablation system10 can be actuated (e.g., energized) to ablate the undesirable tissue. In one embodiment, theelectrical ablation system10 may be configured to treat diseased tissue in the gastrointestinal (GI) tract, esophagus, lung, or stomach that may be accessed orally. In another embodiment, theelectrical ablation system10 may be adapted to treat undesirable tissue in the liver or other organs that may be accessible using translumenal access techniques such as, without limitation, NOTES™ techniques, where the electrical ablation devices may be initially introduced through a natural orifice such as the mouth, anus, or vagina and then advanced to the tissue treatment site by puncturing the walls of internal body lumen such as the stomach, intestines, colon, cervix. In various embodiments, theelectrical ablation system10 may be adapted to treat undesirable tissue in the brain, liver, breast, gall bladder, pancreas, or prostate gland, using one or more electrodes positioned percutaneously, transcutaneously, translumenally, minimally invasively, and/or through open surgical techniques, or any combination thereof.
• In one embodiment, theelectrical ablation system10 may be employed in conjunction with aflexible endoscope12, as well as a rigid endoscope, laparoscope, or thoracoscope, such as the GIF-100 model available from Olympus Corporation. In one embodiment, theendoscope12 may be introduced to the tissue treatment region trans-anally through the colon, trans-orally through the esophagus and stomach, trans-vaginally through the cervix, transcutaneously, or via an external incision or keyhole formed in the abdomen in conjunction with a trocar. Theelectrical ablation system10 may be inserted and guided into or proximate the tissue treatment region using theendoscope12. In other embodiments, anendoscope12 is not utilized, and instead other technique, such as ultrasound or a computerized tomography (CT) scan, for example, is used to determine proper instrument placement during the procedure.
• In the embodiment illustrated inFIG. 1, theendoscope12 comprises anendoscope handle34 and an elongate relativelyflexible shaft32. The distal end of theflexible shaft32 may comprise a light source and a viewing port. Optionally, theflexible shaft32 may define one or more channels for receiving various instruments therethrough, such as electrical ablation devices, for example. Images within the field of view of the viewing port are received by an optical device, such as a camera comprising a charge coupled device (CCD) usually located within theendoscope12, and are transmitted to a display monitor (not shown) outside the patient.
• In one embodiment, theelectrical ablation system10 may comprise anelectrical ablation device20, a plurality ofelectrical conductors18, ahandpiece16 comprising anactivation switch62, and anenergy source14, such as an electrical waveform generator, electrically coupled to theactivation switch62 and theelectrical ablation device20. Theelectrical ablation device20 may comprise afirst lumen26 and asecond lumen27. Thefirst lumen26 and thesecond lumen27 may be introduced to the tissue treatment region using a variety of known techniques such as an open incision and a trocar, through one of more of the channels of theendoscope12, percutaneously, or transcutaneously. In some embodiments, thefirst lumen26 and thesecond lumen27 may be relatively rigid or flexible. Additionally, additional lumens may be utilized, such as a larger lumen (not shown) surrounding thefirst lumen26 and thesecond lumen27. Further, ahousing33, or other suitable structure, may be utilized to maintain the relative position of thefirst lumen26 and thesecond lumen27.
• In one embodiment, one or more electrodes (e.g., needle electrodes, balloon electrodes), such as afirst electrodes24 and asecond electrode25, extend out from the distal end of theelectrical ablation device20. In one embodiment, thefirst electrode24 may be configured as the positive electrode and thesecond electrode25 may be configured as the negative electrode. Thefirst electrode24 is electrically connected to a firstelectrical conductor18, or similar electrically conductive lead or wire, which is coupled to the positive terminal of theenergy source14 through theactivation switch62. Thesecond electrode25 is electrically connected to a secondelectrical conductor19, or similar electrically conductive lead or wire, which is coupled to the negative terminal of theenergy source14 through theactivation switch62. Theelectrical conductors18,19 are electrically insulated from each other and surrounding structures except for the electrical connections to therespective electrodes24,25. In various embodiments, theelectrical ablation device20 may be configured to be introduced into or proximate the tissue treatment region using the endoscope12 (laparoscope or thoracoscope), open surgical procedures, or external and non-invasive medical procedures. Theelectrodes24,25 may be referred to herein as endoscopic or laparoscopic electrodes, although variations thereof may be inserted transcutaneously or percutaneously. As previously discussed, either one or bothelectrodes24,25 may be adapted and configured to slideably move in and out oflumens26,27, respectively. In one embodiment, either one or both of theelectrodes24,25 may be formed in a radius (i.e., arcuate, curved). Additionally, as discussed in more detail below, either one or both of theelectrodes24,25 may be rotatable within theirrespective lumens26,27. Various features of one embodiment of the first andsecond electrodes24,25 are described in more detail inFIGS. 2A-D.
• Once theelectrodes24,25 are positioned at the desired location into or proximate the tissue treatment region, theelectrodes24,25 may be connected to or disconnected from theenergy source14 by actuating or de-actuating theswitch62 on thehandpiece16. Theswitch62 may be operated manually or may be mounted on a foot switch (not shown), for example. Theelectrodes24,25 deliver electric field pulses to the undesirable tissue. The electric field pulses may be characterized based on various parameters such as pulse shape, amplitude, frequency, and duration. The electric field pulses may be sufficient to induce irreversible electroporation in the undesirable tissue. The induced potential depends on a variety of conditions such as tissue type, cell size, and electrical pulse parameters. The primary electrical pulse parameter affecting the transmembrane potential for a specific tissue type is the amplitude of the electric field and pulse length that the tissue is exposed to.
• In one embodiment, the first and secondelectrical conductors18,19 may be provided through thehandle28. In the illustrated embodiment, theelectrode24 can be slideably moved in and out of the distal end of thefirst lumen26 using aslide member30 to retract and/or advance thefirst electrode24. Theelectrode25 can be slideably moved in and out of the distal end of thesecond lumen27 using aslide member31 to retract and/or advance thesecond electrode25. In various embodiments either or bothelectrodes24,25 may be coupled to a single slide member, or additional slide members, to advance and retract theelectrodes24,25, e.g., position theelectrodes24,25. In the illustrated embodiment, the firstelectrical conductor18 coupled to thefirst electrode24 is coupled to theslide member30. In this manner, thefirst electrode24, which is slidably movable within the cannula, lumen, or channel defined by thefirst lumen26, can be advanced and retracted with theslide member30. In the illustrated embodiment, the secondelectrical conductor19 coupled to thesecond electrode25 is coupled to theslide member31. In this manner, thesecond electrode25, which is slidably movable within the cannula, lumen, or channel defined by thesecond lumen27, can be advanced and retracted with theslide member31. In one embodiment, various slide members, such as theslide member31, are rotatable. Thus rotation of theslide member30,31 rotates the correspondingelectrode24,25, respectively, at the distal end of theelectrical ablation device20.
• In various other embodiments, transducers orsensors29 may be located in the handle28 (or other suitable location) of theelectrical ablation device20 to sense the force with which theelectrodes24,25 penetrate the tissue in the tissue treatment zone. This feedback information may be useful to determine whether either one or both of theelectrodes24,25 have been properly inserted in the tissue treatment region. As is particularly well known, cancerous tumor tissue tends to be denser than healthy tissue and thus greater force is required to insert theelectrodes24,25 therein. The transducers orsensors29 can provide feedback to the operator, surgeon, or clinician to physically sense when theelectrodes24,25 are placed within the cancerous tumor. The feedback information provided by the transducers orsensors29 may be processed and displayed by circuits located either internally or externally to theenergy source14. Thesensor29 readings may be employed to determine whether theelectrodes24,25 have been properly located within the cancerous tumor thereby assuring that a suitable margin of error has been achieved in locating theelectrodes24,25.
• In one embodiment, the input to theenergy source14 may be connected to a commercial power supply by way of a plug (not shown). The output of theenergy source14 is coupled to theelectrodes24,25, which may be energized using theactivation switch62 on thehandpiece16, or in one embodiment, an activation switch mounted on a foot activated pedal (not shown). Theenergy source14 may be configured to produce electrical energy suitable for electrical ablation, as described in more detail below.
• In one embodiment, theelectrodes24,25 are adapted and configured to electrically couple to the energy source14 (e.g., generator, waveform generator). Once electrical energy is coupled to theelectrodes24,25, an electric field is formed at a distal end of theelectrodes24,25. Theenergy source14 may be configured to generate electric pulses at a predetermined frequency, amplitude, pulse length, and/or polarity that are suitable to induce irreversible electroporation to ablate substantial volumes of undesirable tissue in the treatment region. For example, theenergy source14 may be configured to deliver DC electric pulses having a predetermined frequency, amplitude, pulse length, and/or polarity suitable to induce irreversible electroporation to ablate substantial volumes of undesirable tissue in the treatment region. The DC pulses may be positive or negative relative to a particular reference polarity. The polarity of the DC pulses may be reversed or inverted from positive-to-negative or negative-to-positive a predetermined number of times to induce irreversible electroporation to ablate substantial volumes of undesirable tissue in the treatment region.
• In one embodiment, a timing circuit may be coupled to the output of theenergy source14 to generate electric pulses. The timing circuit may comprise one or more suitable switching elements to produce the electric pulses. For example, theenergy source14 may produce a series of n electric pulses (where n is any positive integer) of sufficient amplitude and duration to induce irreversible electroporation suitable for tissue ablation when the n electric pulses are applied to theelectrodes24,25. In one embodiment, the electric pulses may have a fixed or variable pulse length, amplitude, and/or frequency.
• Theelectrical ablation device20 may be operated either in bipolar or monopolar mode. In bipolar mode, thefirst electrode24 is electrically connected to a first polarity and thesecond electrode25 is electrically connected to the opposite polarity. For example, in monopolar mode, thefirst electrode24 is coupled to a prescribed voltage and thesecond electrode25 is set to ground. In the illustrated embodiment, theenergy source14 may be configured to operate in either the bipolar or monopolar modes with theelectrical ablation system10. In bipolar mode, thefirst electrode24 is electrically connected to a prescribed voltage of one polarity and thesecond electrode25 is electrically connected to a prescribed voltage of the opposite polarity. When more than two electrodes are used, the polarity of the electrodes may be alternated so that any two adjacent electrodes may have either the same or opposite polarities, for example.
• In monopolar mode, it is not necessary that the patient be grounded with a grounding pad. Since amonopolar energy source14 is typically constructed to operate upon sensing a ground pad connection to the patient, the negative electrode of theenergy source14 may be coupled to an impedance simulation circuit. In this manner, the impedance circuit simulates a connection to the ground pad and thus is able to activate theenergy source14. It will be appreciated that in monopolar mode, the impedance circuit can be electrically connected in series with either one of theelectrodes24,25 that would otherwise be attached to a grounding pad.
• In one embodiment, theenergy source14 may be configured to produce RF waveforms at predetermined frequencies, amplitudes, pulse widths or durations, and/or polarities suitable for electrical ablation of cells in the tissue treatment region. One example of a suitable RF energy source is a commercially available conventional, bipolar/monopolar electrosurgical RF generator such as Model Number ICC 350, available from Erbe, GmbH.
• In one embodiment, theenergy source14 may be configured to produce destabilizing electrical potentials (e.g., fields) suitable to induce irreversible electroporation. The destabilizing electrical potentials may be in the form of bipolar/monopolar DC electric pulses suitable for inducing irreversible electroporation to ablate tissue undesirable tissue with theelectrical ablation device20. A commercially available energy source suitable for generating irreversible electroporation electric field pulses in bipolar or monopolar mode is a pulsed DC generator such as Model Number ECM 830, available from BTX Molecular Delivery Systems Boston, Mass. In bipolar mode, thefirst electrode24 may be electrically coupled to a first polarity and thesecond electrode25 may be electrically coupled to a second (e.g., opposite) polarity of theenergy source14. Bipolar/monopolar DC electric pulses may be produced at a variety of frequencies, amplitudes, pulse lengths, and/or polarities. Unlike RF ablation systems, which require high power and energy levels delivered into the tissue to heat and thermally destroy the tissue, irreversible electroporation requires very little energy applied to the tissue to kill the cells of the undesirable tissue using electric field potentials rather than heat. Accordingly, irreversible electroporation systems avoid the detrimental thermal effects of RF ablation systems.
• In one embodiment, theenergy source14 may be coupled to the first andsecond electrodes24,25 by either a wired or a wireless connection. In a wired connection, theenergy source14 is coupled to theelectrodes24,25 by way of theelectrical conductors18,19, as shown. In a wireless connection, theelectrical conductors18,19 may be replaced with a first antenna (not shown) coupled theenergy source14 and a second antenna (not shown) coupled to theelectrodes24,25, wherein the second antenna is remotely located from the first antenna. In one embodiment, the energy source may comprise a wireless transmitter to deliver energy to the electrodes using wireless energy transfer techniques via one or more remotely positioned antennas. As previously discussed, wireless energy transfer or wireless power transmission is the process of transmitting electrical energy from theenergy source14 to an electrical load, e.g., the abnormal cells in the tissue treatment region, without using the interconnectingelectrical conductors18,19.
• In one embodiment, theenergy source14 may be configured to produce DC electric pulses at frequencies in the range of about 1 Hz to about 10,000 Hz, amplitudes in the range of about ±100 to about ±3,000 VDC, and pulse lengths (e.g., pulse width, pulse duration) in the range of about 1 μs to about 100 ms. The polarity of the electric potentials coupled to theelectrodes24,25 may be reversed during an electrical ablation therapy procedure. For example, initially, the DC electric pulses may have a positive polarity and an amplitude in the range of about +100 to about +3,000 VDC. Subsequently, the polarity of the DC electric pulses may be reversed such that the amplitude is in the range of about −100 to about −3,000 VDC. In one embodiment, the undesirable cells in the tissue treatment region may be electrically ablated with DC pulses suitable to induce irreversible electroporation at frequencies of about 10 Hz to about 100 Hz, amplitudes in the range of about +700 to about +1,500 VDC, and pulse lengths of about 10 μs to about 50 μs. In another embodiment, the abnormal cells in the tissue treatment region may be electrically ablated with an electrical waveform having an amplitude of about +500 VDC and pulse duration of about 20 ms delivered at a pulse period T or repetition rate, frequency f=1/T, of about 10 Hz. It has been determined that an electric field strength of about 1,000 V/cm is suitable for destroying living tissue by inducing irreversible electroporation.
• FIGS. 2A-D illustrate one embodiment of theelectrical ablation device20 in various phases of deployment. Theelectrical ablation device20 may be used in conjunction with theelectrical ablation system10 shown inFIG. 1. It will be appreciated that other devices and electrode configurations may be employed without limitation.FIG. 2A illustrates an initial phase of deployment in which thefirst electrode24 is retracted into thefirst lumen26 and thesecond electrode25 is retraced into thesecond lumen27. Theelectrodes24,25 may have dimensions of about 0.5 mm, about 0.75 mm, about 1 mm, or about 1.5 mm in diameter. It will be appreciated that the dimensions of theelectrodes24,25 may be anywhere from about 0.5 mm to about 1.5 mm in diameter. In various embodiments, the diameter of thefirst electrode24 may by different from the diameter of thesecond electrode25. Theelectrical ablation device20 may be introduced into the tissue treatment region through a trocar, for example, or inserted to a tissue treatment region transcutaneously, percutaneously, or other suitable techniques. In one embodiment, thedistal end46 of thefirst lumen26 may comprise a cutting edge, such as a bevel or other sharp edge, to aid in the puncturing/piercing of tissue. Thedistal end47 of thesecond lumen27 may have a similar configuration.
• FIG. 2B illustrates another phase of deployment in which thefirst electrode24 is extended distally from thefirst lumen26 and thesecond electrode25 is extended distally from thesecond lumen27. As illustrated, theelectrodes24,25 may comprise a cutting edge, such as a bevel, on their distal ends-to aid in the puncturing/piercing of tissue. In one embodiment, movement of theslide member30 in the direction indicated byarrow35 extends thefirst electrode24 distally from thefirst lumen26 and movement of theslide member31 in the direction indicated byarrow37 extends thesecond electrode25 distally from thesecond lumen27. In various embodiments, other techniques of extending theelectrodes24,25 may be utilized, such as a linear drive motor, for example. In this phase of deployment, the first andsecond electrodes24,25 may extend distally through the distal end of theelectrical ablation device20 into or proximate the tissue treatment region. In one embodiment, thesecond electrode25 may be formed with a radius, such that it curves or splays when it extends from thesecond lumen27, as illustrated inFIG. 2B.
• Thefirst electrode24 may be retracted into thesecond lumen27 by pulling proximally on theslide member31 in the direction indicated byarrow39 inFIG. 2C. During a medical procedure, thefirst electrode24 may remain inserted into the tissue treatment area. In a retracted position, thefirst electrode24 may be rotated about its longitudinal axis (shown as “A”) as indicated byarrow41. In the illustrated embodiment, theslide member31 may be rotated to rotate thefirst electrode24. Thefirst electrode24 may be rotated in any suitable direction and any suitable number of degrees, such as 45°, 90°, or 135°, for example.FIG. 2D illustrates another phase of deployment in which thefirst electrode24 is in a fully extended position after it has been rotated. To achieve this position, theslide member31 may be moved in the direction indicated byarrow37.
• One or more of theelectrodes24,25 may be retracted, rotated, and then placed in a new location in the tissue treatment region.FIGS. 3A-C are perspective views of one embodiment of theelectrical ablation device20 in various stages of rotation about axis “A.” Such rotation enables the surgeon or clinician to target and treat a larger tissue treatment region without having to remove theelectrical ablation device20 from the tissue treatment area. Thus, thesecond electrode25, for example, may be located in a plurality of positions in and around the tissue treatment region in order to change the distance between thefirst electrode24 and thesecond electrode25 and treat much larger regions of tissue. As shown inFIG. 3A, in a first position, the distal tip of thefirst electrode24 may be separated by a distance “d₁” from the distal tip of thesecond electrode25. As shown inFIG. 3B, in a second position, the distal tip of thefirst electrode24 may be separated by a distance “d₂” from the distal tip of thesecond electrode25. As shown inFIG. 3C, in a third position, the distal tip of thefirst electrode24 may be separated by a distance “d₃” from the distal tip of thesecond electrode25. Furthermore, increasing the radius “r” (FIG. 3A) of thesecond electrode25 and/or the spacing between theelectrodes24,25 enables the generation of an electric field over much larger tissue treatment regions and thus the ablation of larger volumes of undesirable tissue. In this manner, the operator can treat a larger tissue treatment region comprising cancerous lesions, polyps, or tumors, for example.
• It will be appreciated that theelectrical ablation device20 described with reference toFIGS. 1,2A-E, and3A-C may be introduced inside a patient transcutaneously, percutaneously, through an open incision, through a trocar, through a natural orifice, or any combination thereof. In one embodiment, the outside diameter of theelectrical ablation device20 may be sized to fit within a channel of an endoscope and in other embodiments the outside diameter of theelectrical ablation device20 may be sized to fit within a hollow outer sleeve, or trocar, for example. The hollow outer sleeve or trocar may be inserted into the upper gastrointestinal tract of a patient and may be sized to also receive a flexible endoscopic portion of an endoscope (e.g., gastroscope), similar to theendoscope12 described inFIG. 1.
• Although the electrical ablation electrodes according to the described embodiments have been described in terms of the particularneedle type electrodes24,25 as shown and described inFIGS. 1,2A-D, and3A-C those skilled in the art will appreciate that other configurations of electrical ablation electrodes may be employed for the ablation of undesirable tissue, without limitation. In another embodiment, theelectrical ablation device20 may comprise three or more retractable electrodes, one embodiment of which is described below with reference toFIGS. 4A and 4B. In another embodiment, theelectrical ablation device20 may comprise at least one slidable electrode disposed within at least one channel of theflexible shaft32 of theendoscope12. In another embodiment, theelectrical ablation device20 may comprise at least one electrode may be configured to be inserted into the tissue treatment region transcutaneously or percutaneously. Still in various other embodiments, theelectrical ablation device20 may comprise at least one electrode configured to be introduced to the tissue treatment region transcutaneously or percutaneously and at least one other electrode may be configured to be introduced to the tissue treatment region through at least one channel of theflexible shaft32 of theendoscope12. The embodiments, however, are not limited in this context.
• FIGS. 4A-4B illustrate one embodiment of anelectrical ablation device100 comprising multiple needle electrodes. In the illustrated embodiment, theelectrical ablation device100 comprises threeelectrodes124,125,126. It will be appreciated that in one embodiment, theelectrical ablation device100 also may comprise a greater number of needle electrodes. One or more needle electrodes of theelectrical ablation device200 may be formed with a radius. In the illustrated embodiment theelectrode125 and theelectrode126 are both formed with a radius r₁and r₂(FIG. 4A), respectively, such that they curved when extended distally from theelectrical ablation device100.
• Theelectrical ablation device100 may be used in conjunction with theelectrical ablation system10 shown inFIG. 1. It will be appreciated that other devices and electrode configurations may be employed without limitation. Theelectrodes124,125,126 each may have dimensions of about 0.5 mm, about 0.75 mm, about 1 mm, or about 1.5 mm in diameter. It will be appreciated that the dimensions of each of theelectrodes124,125,126 may be anywhere from about 0.5 mm to about 1.5 mm in diameter. Theelectrical ablation device100 may be introduced into the tissue treatment region through a trocar, transcutaneously, percutaneously, or using other suitable techniques.
• Theelectrical ablation device100 comprises essentially the same components as theelectrical ablation device20 described with reference toFIGS. 2A-D. Theelectrical ablation device100 compriseselectrodes124,125,126 that may be individually or simultaneously deployable, retractable, and/or rotatable with respect to the correspondinglumens126,127,128. Theelectrodes124,125,126 extend distally from the distal end of theelectrical ablation device100. In one embodiment, theelectrode124 may be configured as the positive electrode coupled to the anode of the energy source14 (FIG. 1) and theelectrodes125,126 may be configured as the negative electrode coupled to the cathode of the energy source14 (FIG. 1). Once theelectrodes124,125,126 are positioned at the desired location into or proximate the tissue treatment region, theelectrodes124,125,126 may be connected/disconnected from theenergy source14 by actuating/de-actuating the switch62 (FIG. 1).
• Similar to theelectrical ablation device20, thevarious electrodes124,125,126 may be rotatable and the distance between the various electrodes and/or relative positions of theelectrodes124,125,126 may be may be changed. In the illustrated embodiment, two of theelectrodes125,126 are rotatable whereas the other electrode124 s non-rotatable. For example, one of theelectrodes125 may be rotatable about its longitudinal axis (illustrated as “B”) and theother electrode126 may be rotatable about its longitudinal axis (illustrated as “C”).FIG. 4A illustrates therotatable electrodes125,126 in a first position andFIG. 4B illustrates therotatable electrodes125,126 in a second position (i.e., after rotation). Therotatable electrodes125,126 may be rotated using any suitable method, such as by slide members similar to slide member31 (FIGS. 2A-2B). As is to be appreciated, therotatable electrodes125,126 may be retracted into theirrespective lumens127,128 prior to rotation. Once rotated to a desired position, therotatable electrodes125,126 then may be extended distally from the distal end of theablation device100. Such rotation of therotatable electrodes125,126 enables the surgeon or clinician to target and treat a larger tissue treatment region without having to remove theelectrical ablation device100 from the tissue treatment area. Additionally, for embodiments with multiple rotating electrodes, each electrode may be retracted, extended, and rotated independently from the other electrodes.
• FIGS. 5A-5B illustrate the operation ofelectrical ablation device100 in accordance with one non-limiting embodiment. Theelectrodes124,125,126 may be inserted into atissue treatment region144. Thetissue treatment region144 may be representative of a variety of diseased tissues, cancers, tumors, masses, lesions, abnormal tissue growths, for example. In one embodiment, one of therotatable electrodes125 may be rotated in the directions indicated byarrow140 and the otherrotatable electrode126 may be rotated in the directions indicated byarrow142. One of therotatable electrodes125 may be retracted into thelumen127 prior to rotation and the otherrotatable electrode126 may be retracted into thelumen128 prior to rotation. As shown inFIG. 5B, to ablate a portion of thetissue treatment region144, the operator initially may locate one of therotatable electrodes125 at a first position and the otherrotatable electrode126 at a second position. Once therotatable electrodes125,126 are located into or proximate thetissue treatment region144, all of theelectrodes124,125,126 are energized with irreversible electroporation pulses to create a first necrotic zone146 having a first shape substantially similar to that shown inFIG. 5B. For example, once therotatable electrodes125,126 are located in the desired positions, thetissue treatment region144 may be exposed to an electric field generated by energizing all of theelectrodes124,125,126 with the energy source14 (FIG. 1). The electric field may have a magnitude, frequency, and pulse length suitable to induce irreversible electroporation in thetissue treatment region144 to create the first necrotic zone146 having a first shape. The size of the necrotic zone146 is substantially dependent on the size, separation, and orientation of therotatable electrodes125,126, as previously discussed. The treatment time is defined as the time that therotatable electrodes125,126 are activated or energized to generate the electric pulses suitable for inducing irreversible electroporation in thetissue treatment region144.
• This procedure may be repeated to destroy relatively larger portions of thetissue treatment region144 through rotation of at least one of therotatable electrodes125,126. As illustrated inFIG. 5C, one of therotatable electrodes125 has been rotated to a second position. Prior to rotating, one of therotatable electrodes125 is retracted by pulling on an associated slide member (not shown) in a direction toward the proximal end. Therotatable electrode125 may then be rotated within thecorresponding lumen127 to the second position. Once therotatable electrode125 is rotated to the second position, it may be advanced to engage thetissue treatment region144 by pushing on the slide member (not shown) in a direction towards the distal end of theelectrical ablation device100. Asecond necrotic zone148 having a second shape substantially as shown is formed upon energizing all of theelectrodes124,125,126. As is to be appreciated, a plurality of necrotic zones having a plurality of shapes may be formed by retracting the at least one of therotatable electrodes125,126, rotating the first electrode(s) to a new location, advancing the first electrode(s) into thetissue treatment region144 and energizing all of theelectrodes124,125,126. This process may be repeated as often as necessary to create any number of necrotic zones. At anytime, the surgeon or clinician can reposition thenon-rotatable electrode124 and begin the process anew. Those skilled in the art will appreciate that similar techniques may be employed to ablate any other undesirable tissues that may be accessible trans-anally through the colon, and/or orally through the esophagus and the stomach using translumenal access techniques. Therefore, the embodiments are not limited in this context.
• FIG. 6 illustrates anelectrical ablation apparatus200 in accordance with various embodiments. Theelectrical ablation apparatus200 may comprise anelongate sheath202. The distal end of theelongate sheath202 may have a cutting edge, such as abevel208, to aid in the puncturing or piercing of tissue. A first andsecond electrode210,212 may be deployable from the distal end of theelongate sheath202. In various embodiments, a greater number of electrodes or lesser number of electrodes may be deployable from the distal end of theelongate sheath202. In one embodiment, asleeve204 at least partially surrounds theelongate sheath202. Thesleeve204 comprises thesecond electrode206. Aninsulator218 may be utilized to electrically isolate theelectrode206 from theelongate sheath202. While thesleeve204 is illustrated as a cylinder, it is to be appreciated that thesleeve204 may be any suitable size, shape, or configuration. The first andsecond electrodes210,212 may be pre-formed with a radius. Upon deployment from the distal end of theelongate sheath202, the first andsecond electrodes210,212 may generally bend toward the proximal end of theelectrical ablation apparatus200 due to their pre-formed radius.
• In one embodiment, at least one of the first andsecond electrodes210,212 is rotatable within theelongate sheath202. Similar to previously discussed embodiments, theelectrical ablation apparatus200 may be inserted into a tissue treatment region and a plurality of necrotic zones having a plurality of shapes may be formed by retracting at least one of theelectrodes210,212, rotating the electrode(s) to a new location, advancing the electrode(s) into the tissue treatment region and energizing theelectrodes206,210,212. This process may be repeated as often as necessary to create any number of necrotic zones, each with a varying shape.
• FIG. 7 illustrates anelectrical ablation apparatus300 in accordance with various embodiments. Theelectrical ablation apparatus300 comprises features similar to theelectrical ablation apparatus200. Theelectrical ablation apparatus300 comprises anelongate sheath302 having abevel308 at the distal end to aid in the puncturing or piercing of tissue. The illustrated embodiment also comprises first andsecond electrodes310,312, each with a pre-formed radius, that are deployable from theelongate sheath302. Thesleeve304 comprises anextension314 extending distally from the distal end of theelectrical ablation apparatus300. Theextension314 may have a sharp distal end. Thesleeve304 and theextension314 may comprise thesecond electrode306. Aninsulator318 may be utilized to electrically isolate theelectrode306 from theelongate sheath302. Theextension314 may be used to pierce tissue and positionally secure theelectrical ablation apparatus300 proximate to a tissue treatment region. At least one of the first andsecond electrodes310,312 may be rotatable within theelongate sheath302. Similar to theelectrical ablation device200 described with reference toFIG. 6, theelectrical ablation apparatus300 may be inserted into a tissue treatment region to create a plurality of necrotic zones having a plurality of shapes by retracting the at least one of theelectrodes310,312, rotating the electrode(s) to a new location, advancing the electrode(s) into the tissue treatment region and energizing theelectrodes306,310,312. This process may be repeated as often as necessary to create any number of necrotic zones, each with a varying shape. Theextension306 is used to anchor theelectrical ablation device300 during the procedure.
• FIG. 8 illustrates another embodiment of anelectrical ablation apparatus400. Theelectrical ablation apparatus400 may comprise a firstelongate sheath402 and a secondelongate sheath404. The firstelongate sheath402 may be substantially parallel to the secondelongate sheath404. In some embodiments, the firstelongate sheath402 and the secondelongate sheath404 may be coupled together or otherwise formed together. First, second, andthird electrodes424,425,426 are deployable from the firstelongate sheath402. Fourth, fifth, andsixth electrodes427,428,429 are deployable from the secondelongate sheath404. Eachelectrode424,425,426,427,428,429 may be coupled to an energy source (not shown) at a proximal end and configured to couple to a tissue treatment region at the distal end. As illustrated, in various embodiments, some electrodes, such as thefirst electrode424 and thefourth electrode427 may be electrically isolated from the other electrodes. In one embodiment, thefirst electrode424 is at least partially surrounded by aninsulative sleeve432 and the fourth electrode437 is at least partially surrounded by aninsulative sleeve434. In one embodiment, thefirst electrode424 comprises a non-conductivedistal end431 and thesecond electrode427 also comprises a non-conductivedistal end433. In various embodiments, the non-conductive distal ends431,433 comprise ceramic, or another non-conductive material. The use of the non-conductive distal ends431,433 reduces the current density present at the distal end of theelectrodes424,427 when energized.
• Various electrodes of theelectrical ablation apparatus400 may be pre-formed with a radius. In the illustrated embodiment, the second andthird electrodes425,426 and the fifth andsixth electrodes428,429 are formed with a pre-formed radius. Therefore, similar to the previously discussed embodiments, after an initial energization, these electrodes may be retraced into their respective elongate sheaths and rotated in order to change the shape of the necrotic zone when the electrodes are re-introduced into a tissue treatment regain and energized.
• In various embodiments, other electrode configurations may be implemented to create necrotic zones of various shapes within a tissue treatment region. Yet another embodiment of anelectrical ablation apparatus500 is illustrated inFIG. 9. Theelectrical ablation apparatus500 comprises anelongate shaft502. The-distal end of theelongate shaft502 may be sharpened, or otherwise contain a cutting edge, such as abevel504. A plurality of electrodes may be disposed along the elongate shaft, alternating in polarity when in an energized state. In one embodiment, the first andsecond electrodes506,508 may be at a first polarity and a third electrode510 may be at a second polarity when energized. Regardless of the initial polar configuration, the polarity of the electrodes may be reversed by reversing the polarity of the output of the energy source. The third electrode510 may be coupled to an energy source (not shown) via any suitable connection, such as aninsulated conductor512, for example. Similarly, the first andsecond electrodes506,508 may be coupled to an energy source, such as with conductors positioned internal to theelongate shaft502, for example. Afirst insulator514 may be positioned intermediate thefirst electrode506 and the third electrode510 and asecond insulator516 may be positioned intermediate thesecond electrode508 and the third electrode510. In some embodiments, theinsulators514,516 may be coupled to the third electrode510. Theinsulators514,516 prohibit an electrically conductive connection between two adjacent electrodes having opposite polarities.
• In one embodiment, the third electrode510 is slidably engaged with theelongate sheath502. The position along theelongate sheath502 may be controlled by the user at the proximal end of theelectrical ablation apparatus500, such as with a slide member similar to previously discussed embodiments. During a tissue treatment procedure, the third electrode510 is placed in a first position and theelectrical ablation apparatus500 is positioned within a tissue treatment region. As is to be appreciated, theelectrical ablation apparatus500 may be introduced inside a patient endoscopically, transcutaneously, percutaneously, through an open incision, through a trocar, through a natural orifice, or any combination thereof. Once positioned by the user, theelectrodes506,508,510 may be energized to form a necrotic zone having a first shape in the tissue treatment region. The shape of the necrotic zone will be dependent on the position of the third electrode510 relative to the first andsecond electrodes506,508. The use may slide the third electrode510 in-the direction indicated byarrow518 to change the relative position of the third electrode510. When theelectrodes506,508,510 are re-energized, a necrotic zone having a second shape is formed in the tissue treatment region. This process may be repeated as often as necessary to create any number of necrotic zones using theelectrical ablation apparatus500. At anytime, the surgeon or clinician can reposition theelectrical ablation apparatus500 within the tissue treatment region and begin the process anew. Further, as is to be appreciated, theelectrodes506,508,510 may be formed in any suitable configuration. For example, in one embodiment, the third electrode510 comprises a cutting edge to assist in the movement of the third electrode510 through tissue.
• FIG. 10 illustrates anelectrical ablation apparatus600 in accordance with one non-limiting embodiment. Theelectrical ablation apparatus600 comprises anelongate sheath602 and anelectrode624 deployable from the distal end of theelongate sheath602. As illustrated, in various embodiments, theelectrode624 may be at least partially surrounded by aninsulative sleeve632. Theelectrical ablation apparatus600 further comprises afluid nozzle640 configured to deploy a fluid into atissue treatment region644. Thefluid nozzle640 may be coupled to afluid source642 via afluid conduit648. Upon deployment, the fluid640 bores a path in thetissue treatment region644 to create acavity650. The fluid640 may be any suitable conductive solution (e.g., saline solution). After the formation of thecavity650, the fluid640 located in thecavity650 may be electrically connected to a first polarity of anenergy source614 to function as an electrode. Theelectrode624 is supplied energy having an opposite polarity through an electrical coupling to theenergy source614. As current flows through thetissue treatment region644 from thefirst electrode624 to the fluid640 in thecavity650, a necrotic zone having a first shape is formed in thetissue treatment region644. The user of theelectrical ablation apparatus600 then can rotate, or otherwise reposition thefluid nozzle640, and deploy the fluid640 to create a second cavity652 and the process may be repeated to form a third necrotic zone having a second shape. As illustrated, athird cavity654 may be created to form yet a third necrotic zone having a third shape. Various parameters of the fluid and the fluid deployment process, such as a pressure, temperature, duration, may be altered or adjusted according to the type of tissue in thetissue treatment region644 and the desired size of the cavity created. Furthermore, in various embodiments, a plurality offluid nozzles640 and/or a plurality ofelectrodes624 may be utilized by theelectrical ablation apparatus600.
• FIGS. 11A-B illustrate analignment guide700 in accordance with one non-limiting embodiment. Thealignment guide700 assists in the placement and delivery of electrodes to a treatment site inside a patient. As illustrated, thealignment guide700 is positioned on thesurface702 of theskin704 of a patient. The center of thealignment guide700 may be positioned above the center of the targeted tissue (e.g., a tumor). Once placed in the proper position, thealignment guide700 may be secured to thesurface702 of theskin704 using any suitable attachment technique, such as surgical tape. In one embodiment, thealignment guide700 comprises an adhesive on the skin contacting portion to adhere the alignment guide to the patient. Thealignment guide700 may be radio-opaque to allow proper placement through the use of ultrasound, CT guidance, or other techniques, proximate to the target tissue.
• Thealignment guide700 defines apassageway706 configured to receive anelectrical ablation apparatus710. In one embodiment, theelectrical ablation apparatus710 comprises first andsecond electrodes712,714, with eachelectrode712,714 comprising a first end configured to couple to anenergy source720 and a second end configured to couple to a tissue treatment region. In some embodiments, more electrodes, such as athird electrode716, may be utilized. Furthermore, one or more of the electrodes may be pre-formed with a radius so that they curve or splay upon deployment from the distal end of theelectrical ablation apparatus710. According to one embodiment, theelectrical ablation apparatus710 comprises afirst lumen718 configured to receive thefirst electrode712 and asecond lumen722 configured to receive thesecond electrode714. If additional electrodes are utilized, theelectrical ablation apparatus710 also may comprise additional lumens, such as athird lumen724 configured to receive athird electrode716. Thefirst electrode712 may movable between a first position and a second position with respect to the second electrode714 (e.g., through rotation of the electrical ablation apparatus710). A zone of cell necrosis in a first shape is created in a tissue treatment-region when thefirst electrode712 is in a first position and a zone of necrosis in a second shape is created when thefirst electrode712 is in the second position (e.g., subsequent to rotation).
• Theelectrical ablation apparatus710 may further comprise afirst handle730, asecond handle732, and athird handle734. Thehandles730,732,734 are configured to receive thelumens718,722,724. In the illustrated embodiment, thefirst handle730 is configured to be placed against thesurface702 of theskin714 through thepassageway706 of thealignment guide700. Theelectrical ablation apparatus710 is rotatable about the longitudinal axis (shown as “D”) in the directions indicated byarrow738. The second andthird handles730,732 may be moved in the direction indicated byarrow740 in order to pass theelectrodes712,714,716 through theskin704 and into a tissue treatment region (not shown). Once theelectrodes712,714,716 are coupled to the target tissue, theelectrodes712,714,716 may be energized with theenergy source720 using previously discussed techniques to create a necrotic zone having a first shape. The user may then move the second andthird handles730,732 in the direction indicated by arrow742 (FIG. 11B) to remove at least one electrode from the target treatment region. In one embodiment, the center electrode (i.e., the second electrode714) remains engaged with the tissue treatment region to serve as a central pivot as theelectrical ablation apparatus710 is rotated about axis A by the user. Once rotated, the user may once again move the second andthird handles730, in the direction indicated byarrow740 in order to pass the rotatedelectrodes714,716 through theskin704 and into a tissue treatment region at a different location. Once theelectrodes712,714,716 are again coupled to the target tissue, the electrodes may be energized with theenergy source720 to create a necrotic zone having a second shape. This process may be repeated as often as necessary to create any number of necrotic zones using theelectrical ablation apparatus700. Thealignment guide700 serves to ensure proper position of theelectrical ablation apparatus700 during the procedure.
• As illustrated inFIG. 12, thehandle730 may be configured to rotate within thepassageway706 of thealignment guide700. In order to assist the user in the rotation of thehandle730, various alignment aids may be used. For example, the skin contacting portion of thehandle730 may comprise a dye to mark the surface of the skin upon contact. As the user rotates thehandle730 and places it against the skin, a series of marks indicative of previous contacts will be imprinted on the skin. Additionally, as illustrated inFIG. 13, a plurality ofvisual indicators750 may be distributed around the periphery of thealignment guide700. Throughout a procedure, the user lines thehandle730 with the variousvisual indicators750 prior to piercing the skin and underlying target tissue with the electrodes. Through the use of thevisual indicators750, the user can create necrotic zones of varying shapes within the target treatment region.
• In some embodiments, as illustrated inFIG. 14, a plurality of detents may be used to assist the user in positioning thehandle730 during rotation. For example, thealignment guide700 may define a plurality ofnotches752 distributed around the periphery of thepassageway706. Thenotches752 are configured to receive a portion of thehandle730, such as aprotrusion754, during rotation.
• The embodiments of the electrical ablation devices described herein may be introduced inside a patient using minimally invasive or open surgical techniques. In some instances it may be advantageous to introduce the electrical ablation devices inside the patient using a combination of minimally invasive and open surgical techniques. Minimally invasive techniques provide more accurate and effective access to the treatment region for diagnostic and treatment procedures. To reach internal treatment regions within the patient, the electrical ablation devices described herein may be inserted through natural openings of the body such as the mouth, anus, and/or vagina, for example. Minimally invasive procedures performed by the introduction of various medical devices into the patient through a natural opening of the patient are known in the art as NOTES™ procedures. Surgical devices, such as an electrical ablation devices, may be introduced to the treatment region through the channels of the endoscope to perform key surgical activities (KSA), including, for example, electrical ablation of tissues using irreversible electroporation energy. Some portions of the electrical ablation devices may be introduced to the tissue treatment region percutaneously or through small-keyhole-incisions.
• Endoscopic minimally invasive surgical and diagnostic medical procedures are used to evaluate and treat internal organs by inserting a small tube into the body. The endoscope may have a rigid or a flexible tube. A flexible endoscope may be introduced either through a natural body opening (e.g., mouth, anus, and/or vagina). A rigid endoscope may be introduced via trocar through a relatively small-keyhole-incision incisions (usually 0.5-1.5 cm). The endoscope can be used to observe surface conditions of internal organs, including abnormal or diseased tissue such as lesions and other surface conditions and capture images for visual inspection and photography. The endoscope may be adapted and configured with channels for introducing medical instruments to the treatment region for taking biopsies, retrieving foreign objects, and/or performing surgical procedures.
• Once an electrical ablation device is inserted in the human body internal organs may be reached using trans-organ or translumenal surgical procedures. The electrical ablation device may be advanced to the treatment site using endoscopic translumenal access techniques to perforate a lumen, and then, advance the electrical ablation device and the endoscope into the peritoneal cavity. Translumenal access procedures for perforating a lumen wall, inserting, and advancing an endoscope therethrough, and pneumoperitoneum devices for insufflating the peritoneal cavity and closing or suturing the perforated lumen wall are well known. During a translumenal access procedure, a puncture must be formed in the stomach wall or in the gastrointestinal tract to access the peritoneal cavity. One device often used to form such a puncture is a needle knife which is inserted through the channel of the endoscope, and which utilizes energy to penetrate through the tissue. A guidewire is then feed through the endoscope and is passed through the puncture in the stomach wall and into the peritoneal cavity. The needle knife is removed, leaving the guidewire as a placeholder. A balloon catheter is then passed over the guidewire and through the channel of the endoscope to position the balloon within the opening in the stomach wall. The balloon can then be inflated to increase the size of the opening, thereby enabling the endoscope to push against the rear of the balloon and to be feed through the opening and into the peritoneal cavity. Once the endoscope is positioned within the peritoneal cavity, numerous procedures can be performed through the channel of the endoscope.
• The endoscope may be connected to a video camera (single chip or multiple chips) and may be attached to a fiber-optic cable system connected to a “cold” light source (halogen or xenon), to illuminate the operative field. The video camera provides a direct line-of-sight view of the treatment region. If working in the abdomen, the abdomen may be insufflated with carbon dioxide (CO₂) gas to create a working and viewing space. The abdomen is essentially blown up like a balloon (insufflated), elevating the abdominal wall above the internal organs like a dome. CO₂gas is used because it is common to the human body and can be removed by the respiratory system if it is absorbed through tissue.
• Once the electrical ablation devices are located at the target site, the diseased tissue may be electrically ablated or destroyed using the various embodiments of electrodes discussed herein. The placement and location of the electrodes can be important for effective and efficient electrical ablation therapy. For example, the electrodes may be positioned proximal to a treatment region (e.g., target site or worksite) either endoscopically or transcutaneously (percutaneously). In some implementations, it may be necessary to introduce the electrodes inside the patient using a combination of endoscopic, transcutaneous, and/or open techniques. The electrodes may be introduced to the tissue treatment region through a channel of the endoscope, an overtube, or a trocar and, in some implementations, may be introduced through percutaneously or through small-keyhole-incisions.
• Preferably, the various embodiments of the devices described herein will be processed before surgery. First, a new or used instrument is obtained and if necessary cleaned. The instrument can then be sterilized. In one sterilization technique, the instrument is placed in a closed and sealed container, such as a plastic or TYVEK® bag. The container and instrument are then placed in a field of radiation that can penetrate the container, such as gamma radiation, x-rays, or high-energy electrons. The radiation kills bacteria on the instrument and in the container. The sterilized instrument can then be stored in the sterile container. The sealed container keeps the instrument sterile until it is opened in the medical facility.
• It is preferred that the device is sterilized prior to use. This can be done by any number of ways known to those skilled in the art including beta or gamma radiation, ethylene oxide, steam.
• Although the various embodiments of the devices have been described herein in connection with certain disclosed embodiments, many modifications and variations to those embodiments may be implemented. For example, different types of end effectors may be employed. Also, where materials are disclosed for certain components, other materials may be used. The foregoing description and following claims are intended to cover all such modification and variations.
• Any patent, publication, or other disclosure material, in whole or in part, that is said to be incorporated by reference herein is incorporated herein only to the extent that the incorporated materials does not conflict with existing definitions, statements, or other disclosure material set forth in this disclosure. As such, and to the extent necessary, the disclosure as explicitly set forth herein supersedes any conflicting material incorporated herein by reference. Any material, or portion thereof, that is said to be incorporated by reference herein, but which conflicts with existing definitions, statements, or other disclosure material set forth herein will only be incorporated to the extent that no conflict arises between that incorporated material and the existing disclosure material.

Claims (20)

1. An electrical ablation apparatus, comprising:

first and second electrodes, each electrode comprising a first end configured to couple to an energy source and a second end configured to couple to a tissue treatment region;

wherein the first electrode is movable between a first position and a second position with respect to the second electrode;

wherein the first and second electrodes are configured to induce a zone of cell necrosis in a first shape when the first electrode is in the first position; and

wherein the first and second electrodes are configured to induce a zone of necrosis in a second shape when the first electrode is in the second position.

2. The electrical ablation apparatus ofclaim 1, further comprising:

a third electrode;

a first lumen configured to receive the first electrode;

a second lumen configured to receive the second electrode; and

a third lumen configured to receive the third electrode.

3. The electrical ablation apparatus ofclaim 2, wherein the first electrode is pre-formed with a radius and rotatable within the first lumen and the third electrode is pre-formed with a radius and rotatable with the third lumen.

4. The electrical ablation apparatus ofclaim 2, wherein the first, second, and third lumens each have a distal end comprising a cutting edge.

5. The electrical ablation apparatus ofclaim 1, further comprising:

an elongate sheath; and

a sleeve at least partially surrounding the elongate sheath, wherein the sleeve comprises the second electrode.

6. The electrical ablation apparatus ofclaim 5, wherein the first electrode is deployable from a distal end of the elongate sheath and pre-formed with a radius.

7. The electrical ablation apparatus ofclaim 6, wherein the first electrode is rotatable within the elongate sheath.

8. The electrical ablation apparatus ofclaim 1, further comprising:

a first elongate sheath;

a second elongate sheath; and

third and fourth electrodes, each electrode comprising a first end configured to couple to the energy source and a second end configured to couple to the tissue treatment region;

wherein the first and second electrodes are deployable from the first elongate sheath and the third and fourth electrodes are deployable from the second elongate sheath.

9. The electrical ablation apparatus ofclaim 8, wherein the first and third electrodes each are pre-formed with a radius.

10. The electrical ablation apparatus ofclaim 8, wherein the first elongate sheath and the second elongate sheath are substantially parallel.

11. The electrical ablation apparatus ofclaim 1, further comprising:

a fluid nozzle configured to deploy a fluid to bore a path in the tissue treatment region using a fluid, wherein the first electrode is configured to couple to the fluid in the path.

12. The electrical ablation apparatus ofclaim 11, wherein the fluid nozzle is movable.

13. The electrical ablation apparatus ofclaim 11, further comprising a plurality of fluid nozzles.

14. The electrical ablation apparatus ofclaim 1, further comprising:

an elongate shaft, wherein the first electrode is slidably engaged with the elongate sheath.

15. The electrical ablation apparatus ofclaim 14, wherein the second electrode comprises a distal electrode and a proximal electrode each disposed along the elongate shaft.

16. The electrical ablation apparatus ofclaim 15, wherein the first electrode is disposed on the elongate shaft intermediate the distal electrode and the proximal electrode.

17. The electrical ablation apparatus ofclaim 16, further comprising:

a first insulator disposed on the elongate shaft intermediate the distal electrode and the first electrode; and

a second insulator disposed on the elongate shaft intermediate the first electrode and the proximal electrode.

18. An electrical ablation system, comprising:

first and second electrodes, each electrode comprising a first end configured to couple to an energy source and a second end configured to couple to a tissue treatment region, wherein the first electrode is movable between a first position and a second position with respect to the second electrode, wherein the first and second electrodes are configured to induce a zone of cell necrosis in a first shape when the first electrode is in the first position, and wherein the first and second electrodes are configured to induce a zone of necrosis in a second shape when the first electrode is in the second position;

a first lumen configured to receive the first electrode;

a second lumen configured to receive the second electrode;

an alignment guide defining a passageway, wherein the passageway is configured to receive the first and second lumens; and

a handle coupled to the first and second lumens, wherein the handle is configured to rotatably move the first electrode from the first position to the second position.

19. The electrical ablation system ofclaim 18, wherein the alignment guide comprises a plurality of position indicators positioned proximate to the passageway.

20. An electrical ablation apparatus, comprising:

first and second electrodes, each electrode comprising a first end configured to couple to an energy source and a second end configured to couple to a tissue treatment region;

wherein the first electrode is movable between a first position and a second position with respect to the second electrode;

wherein the first and second electrodes are configured to induce a zone of cell necrosis in a first shape when the first electrode is in the first position;

wherein the first and second electrodes are configured to induce a zone of necrosis in a second shape when the first electrode is in the second position; and

wherein a distance between the first and second electrodes is adjustable by rotating at least one of the first and second electrodes about a central axis of the at least one of the first and second electrodes.

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