Source: https://patents.google.com/patent/WO1999020185A1/en
Timestamp: 2019-06-17 07:44:53
Document Index: 473821835

Matched Legal Cases: ['Application No. 09', 'Application No. 08', 'Application No. 08', 'Application No. 09', 'Application No. 60', 'Application No. 60', 'Application No. 08', 'Application No. 08', 'Application No. 09', 'Application No. 09', 'Application No. 09', 'Application No. 08', 'Application No. 08', 'Application No.60']

WO1999020185A1 - Systems and methods for tissue resection, ablation and aspiration - Google Patents
Systems and methods for tissue resection, ablation and aspiration Download PDF
WO1999020185A1
WO1999020185A1 PCT/US1998/022327 US9822327W WO9920185A1 WO 1999020185 A1 WO1999020185 A1 WO 1999020185A1 US 9822327 W US9822327 W US 9822327W WO 9920185 A1 WO9920185 A1 WO 9920185A1
PCT/US1998/022327
Maria B. Ellsberry
Ronald A. Underwood
1997-10-23 Priority to US6299797P priority Critical
1997-12-15 Priority to US08/990,374 priority
1997-12-15 Priority to US08/990,374 priority patent/US6109268A/en
1998-01-21 Priority to US09/010,381 priority patent/US5941722A/en
1998-09-28 Priority to US09/162,110 priority
1998-09-28 Priority to US09/162,110 priority patent/US6461350B1/en
1998-09-28 Priority to US60/062,997 priority
1998-09-28 Priority to US09/010,381 priority
1998-10-20 Application filed by Arthrocare Corporation filed Critical Arthrocare Corporation
1999-04-29 Publication of WO1999020185A1 publication Critical patent/WO1999020185A1/en
The present invention is a continuation-in-part of U.S. Patent Application No. 09/010,381, filed January 21, 1998 (attorney docket A-6), which is a continuation-in- part of U.S. Patent Application No. 08/990,374, filed on December 15, 1997 (Attorney Docket No. E-3), which is a continuation-in-part of application Serial No. 08/485,219, filed on June 7, 1995 (Attorney Docket 16238-000600), now U.S. Patent No. 5,697,281, which is a continuation-in-part of PCT International Application, U.S. National Phase Serial No. PCT/US94/05168, filed on May 10, 1994, now U.S. Patent No. 5,697,909 (Attorney Docket 16238-000440), which was a continuation-in-part of U.S. Patent
Application No. 08/059,681, filed on May 10, 1993 (Attorney Docket 16238-000420), the complete disclosures of which are incorporated herein by reference for all purposes. The present invention also derives priority from U.S. Patent Application No. 09/162,110, filed September 28, 1998 (attorney docket no. D-7) and Provisional Patent Application No. 60/062,997 filed on October 23, 1997 (Attorney Docket No. 16238-007300), the complete disclosures of which are incorporated herein by reference for all purposes.
The present invention is related to commonly assigned co-pending Provisional Patent Application No. 60/062,997, filed on October 23, 1997 (Attorney Docket No. 16238-007400), non-provisional U.S. Patent Application No. 08/977,845, filed November 25, 1997 (attorney docket no. D-2), which is a continuation-in-part of
Application No. 08/562,332, filed November 22, 1995 (attorney docket no. 016238- 000710), the complete disclosures of which are incorporated herein by reference for all purposes. The present invention is also related to Patent Application Nos. 09/109,219, 09/058,571, 08/874,173 and 09/002,315, filed on June 30, 1998, April 10, 1998, June 13, 1997, and January 2, 1998, respectively (Attorney Docket Nos. CB-1, CB-2,
16238-005600 and C-9, respectively) and U.S. Patent Application No. 09/054,323, filed on April 2, 1998 (Attorney Docket No. E-5), U.S. Patent Application No. 09/010,382, filed January 21, 1998 (Attorney Docket A-6), and U.S. Patent Application No. 09/032,375, filed February 27, 1998 (Attorney Docket No. CB-3), U.S. Patent Application Nos. 08/977,845, filed on November 25, 1997 (Attorney Docket No. D-2), 08/942,580, filed on October 2, 1997 (Attorney Docket No. 16238-001300), U.S. Application No. 08/753,227, filed on November 22, 1996 (Docket 16238-002200), U.S. Application No. 08/687792, filed on July 18, 1996 (Docket No. 16238-001600), the complete disclosures of which are incorporated herein by reference for all purposes. The present invention is also related to commonly assigned U.S. Patent No. 5,683,366, filed November 22, 1995 (Attorney Docket 16238-000700), the complete disclosure of which is incorporated herein by reference for all purposes.
RF energy has also been used in liposuction procedures to remove fatty tissue. In particular, microwave and monopolar RF devices have been used to heat and soften fatty tissue so that the tissue can be more readily detached from the adjacent tissue with a suction instrument. Similar to ultrasonic energy, however, current microwave and monopolar RF devices have difficulty controlling excess heat generation at the target site, resulting in undesirable collateral tissue damage. For example, conventional electrosurgical cutting devices typically operate by creating a voltage difference between the active electrode and the target tissue, causing an electrical arc to form across the physical gap between the electrode and tissue. At the point of contact of the electric arcs with tissue, rapid tissue heating occurs due to high current density between the electrode and tissue. This high current density causes cellular fluids to rapidly vaporize into steam, thereby producing a "cutting effect" along the pathway of localized tissue heating. This cutting effect generally results in the production of smoke, or an electrosurgical plume, which can spread bacterial or viral particles from the tissue to the surgical team or to other portions of the patient's body. In addition, the tissue is parted along the pathway of evaporated cellular fluid, inducing undesirable collateral tissue damage in regions surrounding the target tissue site.
SUMMARY OF THE INVENTION The present invention provides systems, apparatus and methods for selectively applying electrical energy to structures within or on the surface of a patient's body. In particular, methods and apparatus are provided for resecting, cutting, partially ablating, aspirating or otherwise removing tissue from a target site, and ablating the tissue in situ. The systems and methods of the present invention are particularly useful for ablation and hemostasis of tissue in sinus surgery (e.g. , chronic sinusitis and/ or removal of polypectomies) and for resecting and ablating soft tissue structures, such as the meniscus and synovial tissue within a joint. In one aspect of the invention, a method comprises introducing a distal end of an electrosurgical instrument, such as a probe or a catheter, to the target site, and aspirating tissue from the target site through one or more aspiration lumen(s) in the instrument. High frequency voltage is applied between one or more aspiration electrode(s) coupled to the aspiration lumen(s) and one or more return electrode(s) so that an electric current flows therebetween. The high frequency voltage is sufficient to remove or ablate at least a portion of the tissue before the tissue passes into the aspiration lumen(s). This partial or total ablation reduces the size of the aspirated tissue fragments to inhibit clogging of the aspiration lumen. The aspiration electrode(s) are usually located near or at the distal opening of the aspiration lumen so that tissue can be partially ablated before it becomes clogged in the aspiration lumen. In some embodiments, the aspiration electrodes(s) are adjacent to the distal opening, or they may extend across the distal opening of the lumen. The latter configuration has the advantage of ensuring that the tissue passing through the aspiration lumen will contact the aspiration electrode(s). In other embodiments, the aspiration electrode(s) may be positioned within the aspiration lumen just proximal of the distal opening. The aspiration electrode(s) may comprise a loop, a coiled structure, a hook, or any other geometry suitable for ablating the aspirated tissue. In an exemplary embodiment, the electrosurgical probe comprises a pair of loop electrodes disposed across the distal end of the suction lumen.
In a specific configuration, the tissue is removed by molecular dissociation or disintegration processes. In these embodiments, the high frequency voltage applied to the electrode terminal(s) is sufficient to vaporize an electrically conductive fluid (e.g. , gel or saline) between the electrode terminal(s) and the tissue. Within the vaporized fluid, a ionized plasma is formed and charged particles (e.g., electrons) are accelerated towards the tissue to cause the molecular breakdown or disintegration of several cell layers of the tissue. This molecular dissociation is accompanied by the volumetric removal of the tissue. The short range of the accelerated charged particles within the plasma layer confines the molecular dissociation process to the surface layer to minimize damage and necrosis to the underlying tissue. This process can be precisely controlled to effect the volumetric removal of tissue as thin as 10 to 150 microns with minimal heating of, or damage to, surrounding or underlying tissue structures. A more complete description of this phenomena is described in commonly assigned U.S. Patent No. 5,683,366, the complete disclosure of which is incorporated herein by reference.
In yet another aspect of the invention, a method comprises positioning one or more active electrode(s) at the target site within a patient's body and applying a suction force to a tissue structure to draw the tissue structure to the active electrode(s). High frequency voltage is then applied between the active electrode(s) and one or more return electrode(s) to ablate the tissue structure. Typically, the tissue structure comprises a flexible or elastic connective tissue, such as synovial tissue. This type of tissue is typically difficult to remove with conventional mechanical and electrosurgery techniques because the tissue moves away from the instrument. The present invention, by contrast, draws the elastic tissue towards the active electrodes, and then ablates this tissue with the mechanisms described above.
In another aspect of the invention, systems, apparatus and methods are provided for selectively applying electrical energy and suction to fatty or adipose tissue to remove the adipose tissue from the patient (e.g., liposuction, abdominoplasty and the like).
In this aspect of the invention, a method for removing adipose or fatty tissue underlying a patient's epidermis in body regions, such as the abdomen, lower torso, thighs, face and neck, is disclosed. This method includes positioning one or more active electrode(s) and one or more return electrode(s) in close proximity to a target region of fatty tissue. A high frequency voltage difference is applied between the active and return electrodes, and the fatty tissue or fragments of the fatty tissue are aspirated from the target region. The high frequency voltage either heats and softens or separates the fatty tissue or completely removes at least a portion of the tissue. In both embodiments, the remaining fatty tissue is more readily detached from the adjacent tissue in the absence of energy, and less mechanical force is required for removal. The bipolar configuration of the present invention controls the flow of current to the immediate region around the distal end of the probe, which minimizes tissue necrosis and the conduction of current through the patient. The residual heat from the electrical energy also provides simultaneous hemostasis of severed blood vessels, which increases visualization and improves recovery time for the patient. The techniques of the present invention produce significantly less thermal energy than many conventional techniques, such as conventional ultrasonic and RF devices, which reduces collateral tissue damage and minimizes pain and postoperative scarring.
In an exemplary embodiment, the tissue may be removed and/or softened by an electrosurgical probe having an aspiration lumen and one or more aspiration electrode(s) to prevent clogging of the lumen. The aspiration electrode(s) are usually located near or at the distal opening of the aspiration lumen so that tissue can be partially ablated before it becomes clogged in the aspiration lumen. In some embodiments, the aspiration electrodes(s) are adjacent to the distal opening, or they may extend across the distal opening of the lumen. The latter configuration has the advantage of ensuring that the fatty tissue passing through the aspiration lumen will contact the aspiration electrode(s). In other embodiments, the aspiration electrode(s) may be positioned within the aspiration lumen just proximal of the distal opening. This embodiment has the advantage of eliminating any possibility of contact between the surrounding tissue and the return electrode. The aspiration electrode(s) may comprise a loop, a coiled structure, a hook, or any other geometry suitable for ablating the aspirated tissue. In one representative embodiment, the electrosurgical probe comprises a pair of loop electrodes disposed across the distal end of the suction lumen. A more complete description of such a device can be found in Serial No. 09/010,382, filed January 21, 1998 (attorney docket A- 6), previously incorporated herein by reference.
The return electrode(s) are preferably spaced from the active electrode(s) a sufficient distance to prevent arcing therebetween at the voltages suitable for tissue removal, and to prevent contact of the return electrode(s) with the target tissue. The current flow path between the active and return electrodes may be generated by directing an electrically conducting fluid along a fluid path past the return electrode and to the target site, or by locating a viscous electrically conducting fluid, such as a gel, at the target site, and submersing the active and return electrode(s) within the conductive gel. The electrically conductive fluid will be selected to have sufficient electrical conductivity to allow current to pass therethrough from the active to the return electrode, and such that the fluid ionizes into a plasma when subject to sufficient electrical energy, as discussed below. In the exemplary embodiment, the conductive fluid is isotonic saline, although other fluids may be selected, as described in co-pending Provisional Patent Application No.60/098, 122, filed August 27, 1998 (attorney docket no.CB-7P), the complete disclosure of which is incorporated herein by reference.
In the exemplary embodiment, the adipose tissue is removed with molecular dissociation or disintegration processes. Conventional electrosurgery cuts through tissue by rapidly heating the tissue until cellular fluids explode, producing a cutting effect along the pathway of localized heating. The present invention volumetrically removes the tissue along the cutting pathway in a cool ablation process that minimizes thermal damage to surrounding tissue. In these processes, the high frequency voltage applied to the active electrode(s) is sufficient to vaporize an electrically conductive fluid (e.g., gel or saline) between the electrode(s) and the tissue. Within the vaporized fluid, a ionized plasma is formed and charged particles (e.g., electrons) are accelerated towards the tissue to cause the molecular breakdown or disintegration of several cell layers of the tissue. This molecular dissociation is accompanied by the volumetric removal of the tissue. The short range of the accelerated charged particles within the plasma layer confines the molecular dissociation process to the surface layer to minimize damage and necrosis to the underlying tissue. This process can be precisely controlled to effect the volumetric removal of tissue as thin as 10 to 50 microns with minimal heating of, or damage to, surrounding or underlying tissue structures. A more complete description of this phenomena is described in commonly assigned U.S. Patent No. 5,683,366, the complete disclosure of which is incorporated herein by reference.
The present invention offers a number of advantages over current RF, ultrasonic, microwave and laser techniques for removing or softening tissue. The ability to precisely control the volumetric removal of tissue results in a field of tissue removal that is very defined, consistent and predictable. This precise heating also helps to minimize or completely eliminate damage to healthy tissue structures or nerves that are often adjacent to the target tissue. In addition, small blood vessels within the skin tissue are simultaneously cauterized and sealed as the tissue is removed to continuously maintain hemostasis during the procedure. This increases the surgeon's field of view, and shortens the length of the procedure. Moreover, since the present invention allows for the use of electrically conductive fluid (contrary to prior art bipolar and monopolar electrosurgery techniques), isotonic saline may be used during the procedure. Saline is the preferred medium for irrigation because it has the same concentration as the body's fluids and, therefore, is not absorbed into the body as much as other fluids. BRIEF DESCRIPTION OF THE DRAWINGS
Fig. 1 is a perspective view of an electrosurgical system incorporating a power supply and an electrosurgical probe for tissue ablation, resection, incision, contraction and for vessel hemostasis according to the present invention; Fig. 2 is a side view of an electrosurgical probe according to the present invention incorporating a loop electrode for resection and ablation of tissue;
Fig. 4 is an exploded view of a proximal portion of the electrosurgical probe; Figs. 5 A and 5B are end and cross-sectional views, respectively, of the proximal portion of the probe;
Fig. 8 is a side view of another electrosurgical probe according to the present invention incorporating aspiration electrodes for ablating aspirated tissue fragments and/or tissue strands, such as synovial tissue; Fig. 9 is an end view of the probe of Fig. 8;
Figs. 11-13 illustrate alternative probes according to the present invention, incorporating aspiration electrodes; Fig. 14 illustrates an endoscopic sinus surgery procedure, wherein an endoscope is delivered through a nasal passage to view a surgical site within the nasal cavity of the patient;
Fig. 15 illustrates an endoscopic sinus surgery procedure with one of the probes described above according to the present invention; Figs. 16A and 16B illustrate a detailed view of the sinus surgery procedure, illustrating ablation of tissue according to the present invention;
Fig. 17 illustrates a procedure for treating obstructive sleep disorders, such as sleep apnea, according to the present invention; Fig. 18 is a perspective view of another embodiment of the present invention;
Fig. 19 is a side-cross-sectional view of the electrosurgical probe of Fig. 18; Fig. 20 is an enlarged detailed cross-sectional view of the distal end portion of the probe of Fig. 18;
Figs. 21 and 22 are end and front views, respectively, of the probe of Fig. 18.
Fig. 23 illustrates a method for removing fatty tissue in the abdomen, groin or thighs region of a patient according to the present invention; and
The present invention provides systems and methods for selectively applying electrical energy to a target location within or on a patient's body. The present invention is particularly useful in procedures where the tissue site is flooded or submerged with an electrically conducting fluid, such as arthroscopic surgery of the knee, shoulder, ankle, hip, elbow, hand or foot. In addition, the present invention may be used for selectively applying electrical energy to a target location within or on a patient's body, particularly including procedures on an external body surface, such as epidermal and dermal tissues in the skin, or the underlying cutaneous tissue. For convenience, the remaining disclosure will be directed specifically to procedures for removing fatty or adipose tissue underlying the epidermal and dermal skin layers, such as liposuction, abdominoplasties, or other lipectomy procedures. In addition, tissues which may be treated by the system and method of the present invention include, but are not limited to, prostate tissue and leiomyomas (fibroids) located within the uterus, gingival tissues and mucosal tissues located in the mouth, tumors, scar tissue, myocardial tissue, collagenous tissue within the eye or epidermal and dermal tissues on the surface of the skin. Other procedures include laminectomy/disketomy procedures for treating herniated disks, decompressive laminectomy for stenosis in the lumbosacral and cervical spine, posterior lumbosacral and cervical spine fusions, treatment of scoliosis associated with vertebral disease, foraminotomies to remove the roof of the intervertebral foramina to relieve nerve root compression and anterior cervical and lumbar diskectomies. The present invention is also useful for resecting tissue within accessible sites of the body that are suitable for electrode loop resection, such as the resection of prostate tissue, leiomyomas (fibroids) located within the uterus and other diseased tissue within the body.
The present invention is also useful for procedures in the head and neck, such as the ear, mouth, pharynx, larynx, esophagus, nasal cavity and sinuses. These procedures may be performed through the mouth or nose using speculae or gags, or using endoscopic techniques, such as functional endoscopic sinus surgery (FESS). These procedures may include the removal of swollen tissue, chronically-diseased inflamed and hypertrophic mucus linings, polyps and/or neoplasms from the various anatomical sinuses of the skull, the turbinates and nasal passages, in the tonsil, adenoid, epi-glottic and supra- glottic regions, and salivary glands, submucus resection of the nasal septum, excision of diseased tissue and the like. In other procedures, the present invention may be useful for collagen shrinkage, ablation and/or hemostasis in procedures for treating snoring and obstructive sleep apnea (e.g., soft palate, such as the uvula, or tongue/pharynx stiffening, and midline glossectomies), for gross tissue removal, such as tonsillectomies, adenoidectomies, tracheal stenosis and vocal cord polyps and lesions, or for the resection or ablation of facial tumors or tumors within the mouth and pharynx, such as glossectomies, laryngectomies, acoustic neuroma procedures and nasal ablation procedures. In addition, the present invention is useful for procedures within the ear, such as stapedotomies, tympanostomies or the like.
The present invention may also be useful for cosmetic and plastic surgery procedures in the head and neck. For example, the present invention is particularly useful for ablation and sculpting of cartilage tissue, such as the cartilage within the nose that is sculpted during rhinoplasty procedures. The present invention may also be employed for skin tissue removal and/or collagen shrinkage in the epidermis or dermis tissue in the head and neck, e.g., the removal of pigmentations, vascular lesions (e.g., leg veins), scars, tattoos, etc., and for other surgical procedures on the skin, such as tissue rejuvenation, cosmetic eye procedures (blepharoplasties), wrinkle removal, tightening muscles for facelifts or browlifts, hair removal and/or transplant procedures, etc. For convenience, the remaining disclosure will be directed specifically to the resection and/or ablation of the meniscus and the synovial tissue within a joint during an arthroscopic procedure and to the ablation, resection and/or aspiration of sinus tissue during an endoscopic sinus surgery procedure, but it will be appreciated that the system and method can be applied equally well to procedures involving other tissues of the body, as well as to other procedures including open procedures, intravascular procedures, urology, laparoscopy, arthroscopy, thoracoscopy or other cardiac procedures, dermatology, orthopedics, gynecology, otorhinolaryngology, spinal and neurologic procedures, oncology and the like. In the present invention, high frequency (RF) electrical energy is applied to one or more electrode terminals in the presence of electrically conductive fluid to remove and/or modify the structure of tissue structures. Depending on the specific procedure, the present invention may be used to: (1) volumetrically remove tissue, bone or cartilage (i.e., ablate or effect molecular dissociation of the tissue structure); (2) cut or resect tissue; (3) shrink or contract collagen connective tissue; and/ or (4) coagulate severed blood vessels. In other embodiments, the present invention applies high frequency (RF) electrical energy to one or more electrode terminals underlying an external body surface, such as the outer surface of the skin, to soften and/or ablate fatty tissue in order to aspirate the fatty tissue from the patient's body. Depending on the specific procedure, the present invention may be used to: (1) volumetrically remove the fatty tissue (i.e. , ablate or effect molecular dissociation of the tissue structure); (2) decouple or soften fatty tissue from adjacent tissue so that the fatty tissue can be more easily aspirated; (3) shrink or contract collagen connective tissue; and/or (4) coagulate blood vessels underlying the surface of the skin. In one aspect of the invention, systems and methods are provided for the volumetric removal or ablation of tissue structures. In these procedures, a high frequency voltage difference is applied between one or more electrode terminal(s) and one or more return electrode(s) to develop high electric field intensities in the vicinity of the target tissue site. The high electric field intensities lead to electric field induced molecular breakdown of target tissue through molecular dissociation (rather than thermal evaporation or carbonization). Applicant believes that the tissue structure is volumetrically removed through molecular disintegration of larger organic molecules into smaller molecules and/or atoms, such as hydrogen, oxides of carbon, hydrocarbons and nitrogen compounds. This molecular disintegration completely removes the tissue structure, as opposed to dehydrating the tissue material by the removal of liquid within the cells of the tissue, as is typically the case with electrosurgical desiccation and vaporization.
The high electric field intensities may be generated by applying a high frequency voltage that is sufficient to vaporize an electrically conducting fluid over at least a portion of the electrode terminal(s) in the region between the distal tip of the electrode terminal(s) and the target tissue. The electrically conductive fluid may be a gas or liquid, such as isotonic saline, delivered to the target site, or a viscous fluid, such as a gel, that is located at the target site. In the latter embodiment, the electrode terminal(s) are submersed in the electrically conductive gel during the surgical procedure. Since the vapor layer or vaporized region has a relatively high electrical impedance, it increases the voltage differential between the electrode terminal tip and the tissue and causes ionization within the vapor layer due to the presence of an ionizable species (e.g. , sodium when isotonic saline is the electrically conducting fluid). This ionization, under optimal conditions, induces the discharge of energetic electrons and photons from the vapor layer and to the surface of the target tissue. This energy may be in the form of energetic photons (e.g., ultraviolet radiation), energetic particles (e.g. , electrons) or a combination thereof. A more detailed description of this cold ablation phenomena, termed Coblation™, can be found in commonly assigned U.S. Patent No. 5,683,366 the complete disclosure of which is incorporated herein by reference.
The present invention is particularly useful for removing or ablating tissue around nerves, such as spinal or cranial nerves, e.g., the olfactory nerve on either side of the nasal cavity, the optic nerve within the optic and cranial canals, the palatine nerve within the nasal cavity, soft palate, uvula and tonsil, etc. One of the significant drawbacks with the prior art microdebriders and lasers is that these devices do not differentiate between the target tissue and the surrounding nerves or bone. Therefore, the surgeon must be extremely careful during these procedures to avoid damage to the bone or nerves within and around the nasal cavity. In the present invention, the Coblation™ process for removing tissue results in extremely small depths of collateral tissue damage as discussed above. This allows the surgeon to remove tissue close to a nerve without causing collateral damage to the nerve fibers. In addition to the generally precise nature of the novel mechanisms of the present invention, applicant has discovered an additional method of ensuring that adjacent nerves are not damaged during tissue removal. According to the present invention, systems and methods are provided for distinguishing between the fatty tissue immediately surrounding nerve fibers and the normal tissue that is to be removed during the procedure. Nerves usually comprise a connective tissue sheath, or endoneurium, enclosing the bundles of nerve fibers to protect these nerve fibers. This protective tissue sheath typically comprises a fatty tissue (e.g., adipose tissue) having substantially different electrical properties than the normal target tissue, such as the turbinates, polyps, mucus tissue or the like, that are, for example, removed from the nose during sinus procedures. The system of the present invention measures the electrical properties of the tissue at the tip of the probe with one or more electrode terminal(s). These electrical properties may include electrical conductivity at one, several or a range of frequencies (e.g., in the range from 1 kHz to 100 MHz), dielectric constant, capacitance or combinations of these. In this embodiment, an audible signal may be produced when the sensing electrode(s) at the tip of the probe detects the fatty tissue surrounding a nerve, or direct feedback control can be provided to only supply power to the electrode terminal(s) either individually or to the complete array of electrodes, if and when the tissue encountered at the tip or working end of the probe is normal tissue based on the measured electrical properties. In one embodiment, the current limiting elements (discussed in detail above) are configured such that the electrode terminals will shut down or turn off when the electrical impedance reaches a threshold level. When this threshold level is set to the impedance of the fatty tissue surrounding nerves, the electrode terminals will shut off whenever they come in contact with, or in close proximity to, nerves. Meanwhile, the other electrode terminals, which are in contact with or in close proximity to nasal tissue, will continue to conduct electric current to the return electrode. This selective ablation or removal of lower impedance tissue in combination with the Coblation™ mechanism of the present invention allows the surgeon to precisely remove tissue around nerves or bone. In addition to the above, applicant has discovered that the Coblation™ mechanism of the present invention can be manipulated to ablate or remove certain tissue structures, while having little effect on other tissue structures. As discussed above, the present invention uses a technique of vaporizing electrically conductive fluid to form a plasma layer or pocket around the electrode terminal(s), and then inducing the discharge of energy from this plasma or vapor layer to break the molecular bonds of the tissue structure. Based on initial experiments, applicants believe that the free electrons within the ionized vapor layer are accelerated in the high electric fields near the electrode tip(s) . When the density of the vapor layer (or within a bubble formed in the electrically conducting liquid) becomes sufficiently low (i.e. , less than approximately 1020 atoms/cm3 for aqueous solutions), the electron mean free path increases to enable subsequently injected electrons to cause impact ionization within these regions of low density (i.e., vapor layers or bubbles). Energy evolved by the energetic electrons (e.g. , 4 to 5 eV) can subsequently bombard a molecule and break its bonds, dissociating a molecule into free radicals, which then combine into final gaseous or liquid species.
The energy evolved by the energetic electrons may be varied by adjusting a variety of factors, such as: the number of electrode terminals; electrode size and spacing; electrode surface area; asperities and sharp edges on the electrode surfaces; electrode materials; applied voltage and power; current limiting means, such as inductors; electrical conductivity of the fluid in contact with the electrodes; density of the fluid; and other factors. Accordingly, these factors can be manipulated to control the energy level of the excited electrons. Since different tissue structures have different molecular bonds, the present invention can be configured to break the molecular bonds of certain tissue, while having too low an energy to break the molecular bonds of other tissue. For example, fatty tissue, (e.g. , adipose) tissue has double bonds that require a substantially higher energy level than 4 to 5 eV to break. Accordingly, the present invention in its current configuration generally does not ablate or remove such fatty tissue. Of course, factors may be changed such that these double bonds can be broken (e.g. , increasing voltage or changing the electrode configuration to increase the current density at the electrode tips). In another aspect of the invention, a loop electrode is employed to resect, shape or otherwise remove tissue fragments from the treatment site, and one or more electrode terminals are employed to ablate (i.e., break down the tissue by processes including molecular dissociation or disintegration) the non-ablated tissue fragments in situ. Once a tissue fragment is cut, partially ablated or resected by the loop electrode, one or more electrode terminals will be brought into close proximity to these fragments (either by moving the probe into position, or by drawing the fragments to the electrode terminals with a suction lumen). Voltage is applied between the electrode terminals and the return electrode to volumetrically remove the fragments through molecular dissociation, as described above. The loop electrode and the electrode terminals are preferably electrically isolated such that, for example, current can be limited (passively or actively) or completely interrupted to the loop electrode as the surgeon employs the electrode terminals to ablate tissue fragments (and vice versa). In another aspect of the invention, the loop electrode(s) are employed only to ablate tissue using the Coblation™ mechanisms described above. In these embodiments, the loop electrode(s) provides a relatively uniform smooth cutting or ablation effect across the tissue. In addition, loop electrodes generally have a larger surface area exposed to electrically conductive fluid (as compared to the smaller electrode terminals described above), which increases the rate of ablation of tissue. Preferably, the loop electrode(s) extend a sufficient distance from the electrode support member selected to achieve a desirable ablation rate, while minimizing power dissipation into the surrounding medium (which could cause undesirable thermal damage to surrounding or underlying tissue). In an exemplary embodiment, the loop electrode has a length from one end to the other end of about 0.5 to 20 mm, usually about 1 to 8 mm. The loop electrode usually extends about 0.25 to 10 mm from the distal end of the support member, preferably about 1 to 4 mm.
In some embodiments, the loop electrode(s) will have a "non-active" portion or surface to selectively reduce undesirable current flow from the non-active portion or surface into tissue or surrounding electrically conducting liquids (e.g. , isotonic saline, blood or blood/non-conducting irrigant mixtures). Preferably, the "non-active" electrode portion will be coated with an electrically insulating material. This can be accomplished, for example, with plasma deposited coatings of an insulating material, thin-film deposition of an insulating material using evaporative or sputtering techniques (e.g., SiO2 or Si3N4), dip coating, or by providing an electrically insulating support member to electrically insulate a portion of the external surface of the electrode. The electrically insulated non- active portion of the active electrode(s) allows the surgeon to selectively resect and/or ablate tissue, while minimizing necrosis or ablation of surrounding non-target tissue or other body structures.
In addition, the loop electrode(s) may comprise a single electrode extending from first and second ends to an insulating support in the shaft, or multiple, electrically isolated electrodes extending around the loop. One or more return electrodes may also be positioned along the loop portion. Further descriptions of these configurations can be found in U.S. application Serial No. 08/687792, filed on July 18, 1996 (Docket No. 16238-001600), which as already been incorporated herein by reference.
The electrosurgical probe will comprise a shaft or a handpiece having a proximal end and a distal end which supports one or more electrode terminal(s). The shaft or handpiece may assume a wide variety of configurations, with the primary purpose being to mechanically support the active electrode and permit the treating physician to manipulate the electrode from a proximal end of the shaft. The shaft may be rigid or flexible, with flexible shafts optionally being combined with a generally rigid external tube for mechanical support. The distal portion of the shaft may comprise a flexible material, such as plastics, malleable stainless steel, etc. , so that the physician can mold the distal portion into different configurations for different applications. Flexible shafts may be combined with pull wires, shape memory actuators, and other known mechanisms for effecting selective deflection of the distal end of the shaft to facilitate positioning of the electrode array. The shaft will usually include a plurality of wires or other conductive elements running axially therethrough to permit connection of the electrode array to a connector at the proximal end of the shaft. Thus, the shaft will typically have a length of at least 5cm for oral procedures and at least 10 cm, more typically being 20 cm, or longer for endoscopic procedures. The shaft will typically have a diameter of at least 0.5 mm and frequently in the range from 1 to 10 mm. Of course, for dermatological procedures on the outer skin, the shaft may have any suitable length and diameter that would facilitate handling by the surgeon.
For procedures within the nose, the shaft will have a suitable diameter and length to allow the surgeon to reach the target site (e.g., a blockage in the nasal cavity or one of the sinuses) by delivering the probe shaft through one of the nasal passages or another opening (e.g., an opening in the eye or through an opening surgically creating during the procedure). Thus, the shaft will usually have a length in the range of about 5- 25 cm, and a diameter in the range of about 0.5 to 5 mm. For procedures requiring the formation of a small hole or channel in tissue, such as treating swollen turbinates, the shaft diameter will usually be less than 3 mm, preferably less than about 1 mm. Likewise, for procedures in the ear, the shaft should have a length in the range of about 3 to 20 cm, and a diameter of about 0.3 to 5 mm. For procedures in the mouth or upper throat, the shaft will have any suitable length and diameter that would facilitate handling by the surgeon. For procedures in the lower throat, such as laryngectomies, the shaft will be suitably designed to access the larynx. For example, the shaft may be flexible, or have a distal bend to accommodate the bend in the patient's throat. In this regard, the shaft may be a rigid shaft having a specifically designed bend to correspond with the geometry of the mouth and throat, or it may have a flexible distal end, or it may be part of a catheter. In any of these embodiments, the shaft may also be introduced through rigid or flexible endoscopes. Specific shaft designs will be described in detail in connection with the figures hereinafter.
The current flow path between the electrode terminal(s) and the return electrode(s) may be generated by submerging the tissue site in an electrical conducting fluid (e.g. , within a viscous fluid, such as an electrically conductive gel) or by directing an electrically conducting fluid along a fluid path to the target site (i.e., a liquid, such as isotonic saline, or a gas, such as argon). This latter method is particularly effective in a dry environment (i.e., the tissue is not submerged in fluid) because the electrically conducting fluid provides a suitable current flow path from the electrode terminal to the return electrode. A more complete description of an exemplary method of directing electrically conducting fluid between the active and return electrodes is described in parent application Serial No. 08/485,219, filed June 7, 1995 (docket no. 16238-000600), previously incorporated herein by reference.
The present invention may use a single active electrode terminal or an electrode array distributed over a contact surface of a probe. In the latter embodiment, the electrode array usually includes a plurality of independently current-limited and/or power- controlled electrode terminals to apply electrical energy selectively to the target tissue while limiting the unwanted application of electrical energy to the surrounding tissue and environment resulting from power dissipation into surrounding electrically conductive liquids, such as blood, normal saline, electrically conductive gel and the like. The electrode terminals may be independently current-limited by isolating the terminals from each other and connecting each terminal to a separate power source that is isolated from the other electrode terminals. Alternatively, the electrode terminals may be connected to each other at either the proximal or distal ends of the probe to form a single wire that couples to a power source. In one configuration, each individual electrode terminal in the electrode array is electrically insulated from all other electrode terminals in the array within said probe and is connected to a power source which is isolated from each of the other electrode terminals in the array or to circuitry which limits or interrupts current flow to the electrode terminal when low resistivity material (e.g. , blood, electrically conductive saline irrigant or electrically conductive gel) causes a lower impedance path between the return electrode and the individual electrode terminal. The isolated power sources for each individual electrode terminal may be separate power supply circuits having internal impedance characteristics which limit power to the associated electrode terminal when a low impedance return path is encountered. By way of example, the isolated power source may be a user selectable constant current source. In this embodiment, lower impedance paths will automatically result in lower resistive heating levels since the heating is proportional to the square of the operating current times the impedance. Alternatively, a single power source may be connected to each of the electrode terminals through independently actuatable switches, or by independent current limiting elements, such as inductors, capacitors, resistors and/or combinations thereof. The current limiting elements may be provided in the probe, connectors, cable, controller or along the conductive path from the controller to the distal tip of the probe. Alternatively, the resistance and/or capacitance may occur on the surface of the active electrode terminal(s) due to oxide layers which form selected electrode terminals (e.g. , titanium or a resistive coating on the surface of metal, such as platinum).
The tip region of the probe may comprise many independent electrode terminals designed to deliver electrical energy in the vicinity of the tip. The selective application of electrical energy to the conductive fluid is achieved by connecting each individual electrode terminal and the return electrode to a power source having independently controlled or current limited channels. The return electrode(s) may comprise a single tubular member of conductive material proximal to the electrode array at the tip which also serves as a conduit for the supply of the electrically conducting fluid between the active and return electrodes. Alternatively, the probe may comprise an array of return electrodes at the distal tip of the probe (together with the active electrodes) to maintain the electric current at the tip. The application of high frequency voltage between the return electrode(s) and the electrode array results in the generation of high electric field intensities at the distal tips of the electrode terminals with conduction of high frequency current from each individual electrode terminal to the return electrode. The current flow from each individual electrode terminal to the return electrode(s) is controlled by either active or passive means, or a combination thereof, to deliver electrical energy to the surrounding conductive fluid while minimizing energy delivery to surrounding (non- target) tissue. The application of a high frequency voltage between the return electrode(s) and the electrode terminal(s) for appropriate time intervals effects cutting, removing, ablating, shaping, contracting or otherwise modifying the target tissue. The tissue volume over which energy is dissipated (i.e. , a high current density exists) may be precisely controlled, for example, by the use of a multiplicity of small electrode terminals whose effective diameters or principal dimensions range from about 5 mm to 0.01 mm, preferably from about 2 mm to 0.05 mm, and more preferably from about 1 mm to 0.1 mm. Electrode areas for both circular and non-circular terminals will have a contact area (per electrode terminal) below 25 mm2, preferably being in the range from 0.0001 mm2 to 1 mm2, and more preferably from 0.005 mm2 to .5 mm2. The circumscribed area of the electrode array is in the range from 0.25 mm2 to 75 mm2, preferably from 0.5 mm2 to 40 mm2, and will usually include at least two isolated electrode terminals, preferably at least five electrode terminals, often greater than 10 electrode terminals and even 50 or more electrode terminals, disposed over the distal contact surfaces on the shaft. The use of small diameter electrode terminals increases the electric field intensity and reduces the extent or depth of tissue heating as a consequence of the divergence of current flux lines which emanate from the exposed surface of each electrode terminal. The area of the tissue treatment surface can vary widely, and the tissue treatment surface can assume a variety of geometries, with particular areas and geometries being selected for specific applications. Active electrode surfaces can have areas in the range from 0.25 mm2 to 75 mm2, usually being from about 0.5 mm2 to 40 mm2. The geometries can be planar, concave, convex, hemispherical, conical, linear "in-line" array or virtually any other regular or irregular shape. Most commonly, the active electrode(s) or electrode terminal(s) will be formed at the distal tip of the electrosurgical probe shaft, frequently being planar, disk-shaped, or hemispherical surfaces for use in reshaping procedures or being linear arrays for use in cutting. Alternatively or additionally, the active electrode(s) may be formed on lateral surfaces of the electrosurgical probe shaft (e.g. , in the manner of a spatula), facilitating access to certain body structures in endoscopic procedures.
In the representative embodiments, the electrode terminals comprise substantially rigid wires protruding outward from the tissue treatment surface of the electrode support member. Usually, the wires will extend about 0.1 to 4.0 mm, preferably about 0.2 to 1 mm, from the distal surface of the support member. In the exemplary embodiments, the electrosurgical probe includes between about two to fifty electrically isolated electrode terminals, and preferably between about three to twenty electrode terminals. The electrically conducting fluid should have a threshold conductivity to provide a suitable conductive path between the return electrode(s) and the electrode terminal(s). The electrical conductivity of the fluid (in units of milliSiemans per centimeter or mS/cm) will usually be greater than 0.2 mS/cm, preferably will be greater than 2 mS/cm and more preferably greater than 10 mS/cm. In an exemplary embodiment, the electrically conductive fluid is isotonic saline, which has a conductivity of about 17 mS/cm.
In some embodiments, the electrode support and the fluid outlet may be recessed from an outer surface of the probe or handpiece to confine the electrically conductive fluid to the region immediately surrounding the electrode support. In addition, the shaft may be shaped so as to form a cavity around the electrode support and the fluid outlet. This helps to assure that the electrically conductive fluid will remain in contact with the electrode terminal(s) and the return electrode(s) to maintain the conductive path therebetween. In addition, this will help to maintain a vapor or plasma layer between the electrode terminal(s) and the tissue at the treatment site throughout the procedure, which reduces the thermal damage that might otherwise occur if the vapor layer were extinguished due to a lack of conductive fluid. Provision of the electrically conductive fluid around the target site also helps to maintain the tissue temperature at desired levels. The voltage applied between the return electrode(s) and the electrode array will be at high or radio frequency, typically between about 5 kHz and 20 MHz, usually being between about 30 kHz and 2.5 MHz, preferably being between about 50 kHz and 500 kHz, more preferably less than 350 kHz, and most preferably between about 100 kHz and 200 kHz. The RMS (root mean square) voltage applied will usually be in the range from about 5 volts to 1000 volts, preferably being in the range from about 10 volts to 500 volts depending on the electrode terminal size, the operating frequency and the operation mode of the particular procedure or desired effect on the tissue (i.e. , contraction, coagulation or ablation). Typically, the peak-to-peak voltage will be in the range of 10 to 2000 volts, preferably in the range of 20 to 1200 volts and more preferably in the range of about 40 to 800 volts (again, depending on the electrode size, the operating frequency and the operation mode).
As discussed above, the voltage is usually delivered in a series of voltage pulses or alternating current of time varying voltage amplitude with a sufficiently high frequency (e.g., on the order of 5 kHz to 20 MHz) such that the voltage is effectively applied continuously (as compared with e.g. , lasers claiming small depths of necrosis, which are generally pulsed about 10 to 20 Hz). In addition, the duty cycle (i.e., cumulative time in any one-second interval that energy is applied) is on the order of about 50% for the present invention, as compared with pulsed lasers which typically have a duty cycle of about 0.0001 % .
The preferred power source of the present invention delivers a high frequency current selectable to generate average power levels ranging from several milliwatts to tens of watts per electrode, depending on the volume of target tissue being heated, and/ or the maximum allowed temperature selected for the probe tip. The power source allows the user to select the voltage level according to the specific requirements of a particular FESS procedure, arthroscopic surgery, dermatological procedure, ophthalmic procedures, open surgery or other endoscopic surgery procedure. A description of a suitable power source can be found in "SYSTEMS AND METHODS FOR ELECTROSURGICAL TISSUE AND FLUID COAGULATION", filed on October 23, 1997 (Attorney Docket No. 16238-007400), the complete disclosure of which has been incorporated herein by reference.
The power source may be current limited or otherwise controlled so that undesired heating of the target tissue or surrounding (non-target) tissue does not occur. In a presently preferred embodiment of the present invention, current limiting inductors are placed in series with each independent electrode terminal, where the inductance of the inductor is in the range of lOuH to 50,000uH, depending on the electrical properties of the target tissue, the desired tissue heating rate and the operating frequency. Alternatively, capacitor-inductor (LC) circuit structures may be employed, as described previously in co- pending PCT application No. PCT/US94/05168, the complete disclosure of which is incorporated herein by reference. Additionally, current limiting resistors may be selected.
Preferably, these resistors will have a large positive temperature coefficient of resistance so that, as the current level begins to rise for any individual electrode terminal in contact with a low resistance medium (e.g. , saline irrigant or conductive gel), the resistance of the current limiting resistor increases significantly, thereby minimizing the power delivery from said electrode terminal into the low resistance medium (e.g. , saline irrigant or conductive gel).
Referring now to Fig. 1, an exemplary electrosurgical system 5 for resection, ablation, coagulation and/or contraction of tissue will now be described in detail. As shown, electrosurgical system 5 generally includes an electrosurgical probe 20 connected to a power supply 10 for providing high frequency voltage to one or more electrode terminals and a loop electrode (not shown in Fig. 1) on probe 20. Probe 20 includes a connector housing 44 at its proximal end, which can be removably connected to a probe receptacle 32 of a probe cable 22. The proximal portion of cable 22 has a connector 34 to couple probe 20 to power supply 10. Power supply 10 has an operator controllable voltage level adjustment 38 to change the applied voltage level, which is observable at a voltage level display 40. Power supply 10 also includes one or more foot pedals 24 and a cable 26 which is removably coupled to a receptacle 30 with a cable connector 28. The foot pedal 24 may also include a second pedal (not shown) for remotely adjusting the energy level applied to electrode terminals 104, and a third pedal (also not shown) for switching between an ablation mode and a coagulation mode. The specific design of a power supply which may be used with the electrosurgical probe of the present invention is described in Provisional patent application entitled "SYSTEMS AND METHODS FOR ELECTROSURGICAL TISSUE AND FLUID COAGULATION" the full disclosure of which has previously been incorporated herein by reference. Figs. 2-5 illustrate an exemplary electrosurgical probe 20 constructed according to the principles of the present invention. As shown in Fig. 2, probe 20 generally includes an elongated shaft 100 which may be flexible or rigid, a handle 204 coupled to the proximal end of shaft 100 and an electrode support member 102 coupled to the distal end of shaft 100. Shaft 100 preferably comprises an electrically conducting material, usually metal, which is selected from the group consisting of tungsten, stainless steel alloys, platinum or its alloys, titanium or its alloys, molybdenum or its alloys, and nickel or its alloys. Shaft 100 includes an electrically insulating jacket 108, which is typically formed as one or more electrically insulating sheaths or coatings, such as polytetrafluoroethylene, polyimide, and the like. The provision of the electrically insulating jacket over the shaft prevents direct electrical contact between these metal elements and any adjacent body structure or the surgeon. Such direct electrical contact between a body structure (e.g. , tendon) and an exposed electrode could result in unwanted heating and necrosis of the structure at the point of contact causing necrosis. Handle 204 typically comprises a plastic material that is easily molded into a suitable shape for handling by the surgeon. As shown in Fig. 3, handle 204 defines an inner cavity 208 that houses the electrical connections 250 (discussed below), and provides a suitable interface for connection to an electrical connecting cable 22 (see Fig. 1). As shown in Fig. 5B, the probe will also include a coding resistor 400 having a value selected to program different output ranges and modes of operation for the power supply. This allows a single power supply to be used with a variety of different probes in different applications (e.g., dermatology, cardiac surgery, neurosurgery, arthroscopy, etc). Electrode support member 102 extends from the distal end of shaft 100 (usually about 1 to 20 mm), and provides support for a loop electrode 103 and a plurality of electrically isolated electrode terminals 104 (see Fig. 4).
As shown in Fig. 3, the distal portion of shaft 100 is preferably bent to improve access to the operative site of the tissue being treated (e.g., contracted). Electrode support member 102 has a substantially planar tissue treatment surface 212 (see Fig. 4) that is usually at an angle of about 10 to 90 degrees relative to the longitudinal axis of shaft 100, preferably about 10 to 30 degrees and more preferably about 15-18 degrees.
In addition, the distal end of the shaft may have a bevel, as described in commonly- assigned patent application Serial No. 562,332 filed November 22, 1995 (Attorney Docket 16238-000700). In alternative embodiments, the distal portion of shaft 100 comprises a flexible material which can be deflected relative to the longitudinal axis of the shaft. Such deflection may be selectively induced by mechanical tension of a pull wire, for example, or by a shape memory wire that expands or contracts by externally applied temperature changes. A more complete description of this embodiment can be found in PCT International Application, U.S. National Phase Serial No. PCT/US94/05168.
As shown in Fig. 4, loop electrode 103 has first and second ends extending from the electrode support member 103. The first and second ends are coupled to, or integral with, a pair of connectors 300, 302, e.g., wires, that extend through the shaft of the probe to its proximal end for coupling to the high frequency power supply. The loop electrode usually extends about 0.5 to about 10 mm from the distal end of support member, preferably about 1 to 2 mm. In the representative embodiment, the loop electrode has a solid construction with a substantially uniform cross-sectional area, e.g., circular, square, etc. Of course, it will be recognized that the ablation electrode may have a wide variety of cross-sectional shapes, such as annular, square, rectangular, L-shaped, V-shaped, D-shaped, C-shaped, star-shaped and crossed-shaped, as described in commonly-assigned co-pending application Serial No. 08/687792. In addition, it should be noted that loop electrode 103 may have a geometry other than that shown in Figs. 2-5, such as a semi-circular loop, a V-shaped loop, a straight wire electrode extending between two support members, and the like. Also, loop electrode may be positioned on a lateral surface of the shaft, or it may extend at a transverse angle from the distal end of the shaft, depending on the particular surgical procedure. Loop electrode 103 usually extends further away from the support member than the electrode terminals 104 to facilitate resection and ablation of tissue. As discussed below, loop electrode 103 is especially configured for resecting fragments or pieces of tissue, while the electrode terminals ablate or cause molecular dissociation or disintegration of the removed pieces from the fluid environment. In the presently preferred embodiment, the probe will include 3 to 7 electrode terminals positioned on either side of the loop electrode. The probe may further include a suction lumen (not shown) for drawing the pieces of tissue toward the electrode terminals after they have been removed from the target site by the loop electrode 103.
Referring to Fig. 4, the electrically isolated electrode terminals 104 are preferably spaced apart over tissue treatment surface 212 of electrode support member 102. The tissue treatment surface and individual electrode terminals 104 will usually have dimensions within the ranges set forth above. In the representative embodiment, the tissue treatment surface 212 has an oval cross-sectional shape with a length L in the range of 1 mm to 20 mm and a width W in the range from 0.3 mm to 7 mm. The oval cross- sectional shape accommodates the bend in the distal portion of shaft 202. The electrode terminals 104 preferably extend slightly outward from surface 212, typically by a distance from 0.2 mm to 2. However, it will be understood that terminals 104 may be flush with this surface, or even recessed, if desired. In one embodiment of the invention, the electrode terminals are axially adjustable relative to the tissue treatment surface so that the surgeon can adjust the distance between the surface and the electrode terminals.
In alternative embodiments, the fluid path may be formed in probe 20 by, for example, an inner lumen or an annular gap (not shown) between the return electrode and a tubular support member within shaft 100. This annular gap may be formed near the perimeter of the shaft 100 such that the electrically conducting fluid tends to flow radially inward towards the target site, or it may be formed towards the center of shaft 100 so that the fluid flows radially outward. In both of these embodiments, a fluid source (e.g. , a bag of fluid elevated above the surgical site or having a pumping device), is coupled to probe 20 via a fluid supply tube (not shown) that may or may not have a controllable valve. A more complete description of an electrosurgical probe incorporating one or more fluid lumen(s) can be found in commonly assigned, co-pending application Serial No. 08/485,219, filed on June 7, 1995 (Attorney Docket 16238-0006000), the complete disclosure of which has previously been incorporated herein by reference. In addition, the probe 20 may include an aspiration lumen (not shown) for aspirating excess conductive fluid, other fluids, such as blood, and/or tissue fragments from the target site. The probe may also include one or more aspiration electrode(s), such as those described below in reference to Figs. 8-12, for ablating the aspirated tissue fragments. Alternatively, the aspiration electrode(s) may comprise the active electrode terminals described above. For example, the probe may have an aspiration lumen with a distal opening positioned adjacent one or more of the active electrode terminals at the distal end of the probe. As tissue fragments are drawn into the aspiration lumen, the active electrode terminals are energized to ablate at least a portion of these fragments to inhibit clogging of the lumen. Referring now to Fig. 6, a surgical kit 300 for resecting and/or ablating tissue within a joint according to the invention will now be described. As shown, surgical kit 300 includes a package 302 for housing a surgical instrument 304, and an instructions for use 306 of instrument 304. Package 302 may comprise any suitable package, such as a box, carton, wrapping, etc. In the exemplary embodiment, kit 300 further includes a sterile wrapping 320 for packaging and storing instrument 304. Instrument 304 includes a shaft 310 having at least one loop electrode 311 and at least one electrode terminal 312 at its distal end, and at least one connector (not shown) extending from loop electrode 311 and electrode terminal 312 to the proximal end of shaft 310. The instrument 304 is generally disposable after a single procedure. Instrument 304 may or may not include a return electrode 316.
Through a central patellar splitting approach, the probe is then placed within the joint through the intercondylar notch, and the attached posterior horn insertion is resected by pressing the loop electrode into the attached posterior fragment. The fragment is then removed with the electrode terminals and the remnant is checked for stability. Referring now to Fig. 7, an exemplary electrosurgical system 411 for treatment of tissue in 'dry fields' will now be described in detail. Of course, system 411 may also be used in 'wet field', i.e. , the target site is immersed in electrically conductive fluid. However, this system is particularly useful in 'dry fields' where the fluid is preferably delivered through electrosurgical probe to the target site. As shown, electrosurgical system 411 generally comprises an electrosurgical handpiece or probe 410 connected to a power supply 428 for providing high frequency voltage to a target site and a fluid source 421 for supplying electrically conducting fluid 450 to probe 410. In addition, electrosurgical system 411 may include an endoscope (not shown) with a fiber optic head light for viewing the surgical site, particularly in sinus procedures or procedures in the ear or the back of the mouth. The endoscope may be integral with probe 410, or it may be part of a separate instrument. The system 411 may also include a vacuum source (not shown) for coupling to a suction lumen or tube 505 (see Fig. 2) in the probe 410 for aspirating the target site.
Similar to the above embodiment, power supply 428 has an operator controllable voltage level adjustment 430 to change the applied voltage level, which is observable at a voltage level display 432. Power supply 428 also includes first, second and third foot pedals 437, 438, 439 and a cable 436 which is removably coupled to power supply 428. The foot pedals 37, 38, 39 allow the surgeon to remotely adjust the energy level applied to electrode terminals 458. In an exemplary embodiment, first foot pedal 437 is used to place the power supply into the "ablation" mode and second foot pedal 438 places power supply 428 into the "coagulation" mode. The third foot pedal 439 allows the user to adjust the voltage level within the "ablation" mode. In the ablation mode, a sufficient voltage is applied to the electrode terminals to establish the requisite conditions for molecular dissociation of the tissue (i.e., vaporizing a portion of the electrically conductive fluid, ionizing charged particles within the vapor layer and accelerating these charged particles against the tissue). As discussed above, the requisite voltage level for ablation will vary depending on the number, size, shape and spacing of the electrodes, the distance in which the electrodes extend from the support member, etc. Once the surgeon places the power supply in the "ablation" mode, voltage level adjustment 430 or third foot pedal 439 may be used to adjust the voltage level to adjust the degree or aggressiveness of the ablation. Of course, it will be recognized that the voltage and modality of the power supply may be controlled by other input devices. However, applicant has found that foot pedals are convenient methods of controlling the power supply while manipulating the probe during a surgical procedure. In the coagulation mode, the power supply 428 applies a low enough voltage to the electrode terminals (or the coagulation electrode) to avoid vaporization of the electrically conductive fluid and subsequent molecular dissociation of the tissue. The surgeon may automatically toggle the power supply between the ablation and coagulation modes by alternatively stepping on foot pedals 437, 438, respectively. This allows the surgeon to quickly move between coagulation and ablation in situ, without having to remove his/her concentration from the surgical field or without having to request an assistant to switch the power supply. By way of example, as the surgeon is sculpting soft tissue in the ablation mode, the probe typically will simultaneously seal and/or coagulation small severed vessels within the tissue. However, larger vessels, or vessels with high fluid pressures (e.g., arterial vessels) may not be sealed in the ablation mode.
Accordingly, the surgeon can simply step on foot pedal 38, automatically lowering the voltage level below the threshold level for ablation, and apply sufficient pressure onto the severed vessel for a sufficient period of time to seal and/or coagulate the vessel. After this is completed, the surgeon may quickly move back into the ablation mode by stepping on foot pedal 437. A specific design of a suitable power supply for use with the present invention can be found in provisional patent application entitled "SYSTEMS AND METHODS FOR ELECTROSURGICAL TISSUE AND FLUID COAGULATION", filed October 23, 1997 (attorney docket no. 16238-007400), previously incorporated herein by reference. Figs. 8-10 illustrate an exemplary electrosurgical probe 490 constructed according to the principles of the present invention. As shown in Fig. 2, probe 490 generally includes an elongated shaft 500 which may be flexible or rigid, a handle 604 coupled to the proximal end of shaft 500 and an electrode support member 502 coupled to the distal end of shaft 500. Shaft 500 preferably includes a bend 501 that allows the distal section of shaft 500 to be offset from the proximal section and handle 604. This offset facilitates procedures that require an endoscope, such as FESS, because the endoscope can, for example, be introduced through the same nasal passage as the shaft 500 without interference between handle 604 and the eyepiece of the endoscope (see Fig. 16). Shaft 500 preferably comprises a plastic material that is easily molded into the shape shown in Fig. 1.
In an alternative embodiment (not shown), shaft 500 comprises an electrically conducting material, usually metal, which is selected from the group comprising tungsten, stainless steel alloys, platinum or its alloys, titanium or its alloys, molybdenum or its alloys, and nickel or its alloys. In this embodiment, shaft 500 includes an electrically insulating jacket 508, which is typically formed as one or more electrically insulating sheaths or coatings, such as polytetrafluoroethylene, polyimide, and the like. The provision of the electrically insulating jacket over the shaft prevents direct electrical contact between these metal elements and any adjacent body structure or the surgeon. Such direct electrical contact between a body structure (e.g. , tendon) and an exposed electrode could result in unwanted heating and necrosis of the structure at the point of contact causing necrosis.
As shown in Fig. 8, the distal portion of shaft 500 is preferably bent to improve access to the operative site of the tissue being treated. Electrode support member 502 has a substantially planar tissue treatment surface 612 that is usually at an angle of about 10 to 90 degrees relative to the longitudinal axis of shaft 600, preferably about 30 to 60 degrees and more preferably about 45 degrees. In alternative embodiments, the distal portion of shaft 500 comprises a flexible material which can be deflected relative to the longitudinal axis of the shaft. Such deflection may be selectively induced by mechanical tension of a pull wire, for example, or by a shape memory wire that expands or contracts by externally applied temperature changes. A more complete description of this embodiment can be found in PCT International Application, U.S. National Phase Serial No. PCT/US94/05168, filed on May 10, 1994 (Attorney Docket 16238-000440), now U.S. Patent No. 5,697,909, the complete disclosure of which has previously been incorporated herein by reference.
In alternative embodiments, the fluid path may be formed in probe 490 by, for example, an inner lumen or an annular gap between the return electrode and a tubular support member within shaft 500. This annular gap may be formed near the perimeter of the shaft 500 such that the electrically conducting fluid tends to flow radially inward towards the target site, or it may be formed towards the center of shaft 500 so that the fluid flows radially outward. In both of these embodiments, a fluid source (e.g., a bag of fluid elevated above the surgical site or having a pumping device), is coupled to probe 490 via a fluid supply tube (not shown) that may or may not have a controllable valve. A more complete description of an electrosurgical probe incorporating one or more fluid lumen(s) can be found in parent application Serial No. 08/485,219, filed on June 7, 1995 (Attorney Docket 16238-0006000), the complete disclosure of which has previously been incorporated herein by reference. Referring to Fig. 9, the electrically isolated electrode terminals 504 are spaced apart over tissue treatment surface 612 of electrode support member 502. The tissue treatment surface and individual electrode terminals 504 will usually have dimensions within the ranges set forth above. As shown, the probe includes a single, larger opening 609 in the center of tissue treatment surface 612, and a plurality of electrode terminals (e.g. , about 3-15) around the perimeter of surface 612 (see Fig. 9). Alternatively, the probe may include a single, annular, or partially annular, electrode terminal at the perimeter of the tissue treatment surface. The central opening 609 is coupled to a suction lumen (not shown) within shaft 500 and a suction tube 611 (Fig. 8) for aspirating tissue, fluids and/or gases from the target site. In this embodiment, the electrically conductive fluid generally flows radially inward past electrode terminals 504 and then back through the opening 609. Aspirating the electrically conductive fluid during surgery allows the surgeon to see the target site, and it prevents the fluid from flowing into the patient's body, e.g. , through the sinus passages, down the patient's throat or into the ear canal. As shown, one or more of the electrode terminals 504 comprise loop electrodes 540 that extend across distal opening 609 of the suction lumen within shaft 500. In the representative embodiment, two of the electrode terminals 504 comprise loop electrodes 540 that cross over the distal opening 609. Of course, it will be recognized that a variety of different configurations are possible, such as a single loop electrode, or multiple loop electrodes having different configurations than shown. In addition, the electrodes may have shapes other than loops, such as the coiled configurations shown in Figs. 11 and 12. Alternatively, the electrodes may be formed within suction lumen proximal to the distal opening 609, as shown in Fig. 13. The main function of loop electrodes 540 is to ablate portions of tissue that are drawn into the suction lumen to prevent clogging of the lumen.
In the representative embodiment, the high frequency voltage is sufficient to convert the electrically conductive fluid (not shown) between the target tissue and electrode terminals 504 into an ionized vapor layer or plasma (not shown). As a result of the applied voltage difference between electrode terminal(s) 504 and the target tissue (i.e., the voltage gradient across the plasma layer), charged particles in the plasma (viz., electrons) are accelerated towards the tissue. At sufficiently high voltage differences, these charged particles gain sufficient energy to cause dissociation of the molecular bonds within tissue structures. This molecular dissociation is accompanied by the volumetric removal (i.e, ablative sublimation) of tissue and the production of low molecular weight gases, such as oxygen, nitrogen, carbon dioxide, hydrogen and methane. The short range of the accelerated charged particles within the tissue confines the molecular dissociation process to the surface layer to minimize damage and necrosis to the underlying tissue. During the process, the gases will be aspirated through opening 609 and suction tube 611 to a vacuum source. In addition, excess electrically conductive fluid, and other fluids (e.g., blood) will be aspirated from the target site to facilitate the surgeon's view. Applicant has also found that tissue fragments are also aspirated through opening 609 into suction lumen and tube 611 during the procedure. These tissue fragments are ablated or dissociated with loop electrodes 540 with a similar mechanism described above. Namely, as electrically conductive fluid and tissue fragments are aspirated into loop electrodes 540, these electrodes are activated so that high frequency voltage is applied to loop electrodes 540 and return electrode 512 (of course, the probe may include a different, separate return electrode for this purpose). The voltage is sufficient to vaporize the fluid, and create a plasma layer between loop electrodes 540 and the tissue fragments so that portions of the tissue fragments are ablated or removed. This reduces the volume of the tissue fragments as they pass through suction lumen to minimize clogging of the lumen.
In addition, the present invention is particularly useful for removing elastic tissue, such as the synovial tissue found in joints. In arthroscopic procedures, this elastic synovial tissue tends to move away from instruments within the conductive fluid, making it difficult for conventional instruments to remove this tissue. With the present invention, the probe is moved adjacent the target synovial tissue, and the vacuum source is activated to draw the synovial tissue towards the distal end of the probe. The aspiration and/or active electrode terminals are then energized to ablate this tissue, This allows the surgeon to quickly and precisely ablate elastic tissue with minimal thermal damage to the treatment site.
Referring now to Figs. 11 and 12, alternative embodiments for aspiration electrodes will now be described. As shown in Fig. 11, the aspiration electrodes may comprise a pair of coiled electrodes 550 that extend across distal opening 609 of the suction lumen. The larger surface area of the coiled electrodes 550 usually increases the effectiveness of the electrodes 550 on tissue fragments passing through opening 609. In Fig. 12, the aspiration electrode comprises a single coiled electrode 552 passing across the distal opening 609 of suction lumen. This single electrode 552 may be sufficient to inhibit clogging of the suction lumen. Alternatively, the aspiration electrodes may be positioned within the suction lumen proximal to the distal opening 609. Preferably, these electrodes are close to opening 609 so that tissue does not clog the opening 609 before it reaches electrodes 554. In this embodiment, a separate return electrode 556 may be provided within the suction lumen to confine the electric currents therein. Referring to Fig. 13, another embodiment of the present invention incorporates an aspiration electrode 560 within the aspiration lumen 562 of the probe. As shown, the electrode 560 is positioned just proximal of distal opening 609 so that the tissue fragments are ablated as they enter lumen 562. In the representation embodiment, the aspiration electrode 560 comprises a loop electrode that stretches across the aspiration lumen 562. However, it will be recognized that many other configurations are possible.
In this embodiment, the return electrode 564 is located outside of the probe as in the previously embodiments. Alternatively, the return electrode(s) may be located within the aspiration lumen 562 with the aspiration electrode 560. For example, the inner insulating coating 563 may be exposed at portions within the lumen 562 to provide a conductive path between this exposed portion of return electrode 564 and the aspiration electrode 560. The latter embodiment has the advantage of confining the electric currents to within the aspiration lumen. In addition, in dry fields in which the conductive fluid is delivered to the target site, it is usually easier to maintain a conductive fluid path between the active and return electrodes in the latter embodiment because the conductive fluid is aspirated through the aspiration lumen 562 along with the tissue fragments.
Figs. 14-17 illustrate a method for treating nasal or sinus blockages, e.g. , chronic sinusitis, according to the present invention. In these procedures, the polyps, turbinates or other sinus tissue may be ablated or reduced (e.g. , by tissue contraction) to clear the blockage and/or enlarge the sinus cavity to reestablish normal sinus function. For example, in chronic rhinitis, which is a collective term for chronic irritation or inflammation of the nasal mucosa with hypertrophy of the nasal mucosa, the inferior turbinate may be reduced by ablation or contraction. Alternatively, a turbinectomy or mucotomy may be performed by removing a strip of tissue from the lower edge of the inferior turbinate to reduce the volume of the turbinate. For treating nasal polypi, which comprises benign pedicled or sessile masses of nasal or sinus mucosa caused by inflammation, the nasal polypi may be contracted or shrunk, or ablated by the method of the present invention. For treating severe sinusitis, a frontal sinus operation may be performed to introduce the electrosurgical probe to the site of blockage. The present invention may also be used to treat diseases of the septum, e.g. , ablating or resecting portions of the septum for removal, straightening or reimplantation of the septum.
Figures 14-17 schematically illustrate an endoscopic sinus surgery (FESS) procedure according to the present invention. As shown in Fig. 14, an endoscope 700 is first introduced through one of the nasal passages 701 to allow the surgeon to view the target site, e.g. , the sinus cavities. As shown, the endoscope 700 will usually comprise a thin metal tube 702 with a lens (not shown) at the distal end 704, and an eyepiece 706 at the proximal end 708. As shown in Fig. 8, the probe shaft 500 has a bend 501 to facilitate use of both the endoscope and the probe 490 in the same nasal passage (i.e., the handles of the two instruments do not interfere with each other in this embodiment). Alternatively, the endoscope may be introduced transorally through the inferior soft palate to view the nasopharynx. Suitable nasal endoscopes for use with the present invention are described in U.S. Patent Nos. 4,517,962, 4,844,052, 4,881,523 and 5, 167,220, the complete disclosures of which are incorporated herein by reference for all purposes. Alternatively, the endoscope 700 may include a sheath (not shown) having an inner lumen for receiving the electrosurgical probe shaft 500. In this embodiment, the shaft 500 will extend through the inner lumen to a distal opening in the endoscope. The shaft will include suitable proximal controls for manipulation of its distal end during the surgical procedure. As shown in Fig. 15, the distal end of probe 490 is introduced through nasal passage 701 into the nasal cavity 703 (endoscope 700 is not shown in Fig. 12). Depending on the location of the blockage, the electrode terminals 504 will be positioned adjacent the blockage in the nasal cavity 703, or in one of the paranasal sinuses 705, 707. Note that only the frontal sinus 705 and the sphenoidal sinus 707 are shown in Fig. 12, but the procedure is also applicable to the ethmoidal and maxillary sinuses. Once the surgeon has reached the point of major blockage, electrically conductive fluid is delivered through tube 633 and opening 637 to the tissue (see Fig. 8). The fluid flows past the return electrode 512 to the electrode terminals 504 at the distal end of the shaft. The rate of fluid flow is controlled with valve 417 (Fig. 8) such that the zone between the tissue and electrode support 502 is constantly immersed in the fluid. The power supply 428 is then turned on and adjusted such that a high frequency voltage difference is applied between electrode terminals 504 and return electrode 512. The electrically conductive fluid provides the conduction path (see current flux lines) between electrode terminals 504 and the return electrode 512.
Figs. 16A and 16B illustrate the removal of sinus tissue in more detail As shown, the high frequency voltage is sufficient to convert the electrically conductive fluid (not shown) between the target tissue 702 and electrode terminal(s) 504 into an ionized vapor layer 712 or plasma. As a result of the applied voltage difference between electrode terminal(s) 504 (or electrode terminal 458) and the target tissue 702 (i.e., the voltage gradient across the plasma layer 712), charged particles 715 in the plasma (viz. , electrons) are accelerated. At sufficiently high voltage differences, these charged particles 715 gain sufficient energy to cause dissociation of the molecular bonds within tissue structures in contact with the plasma field. This molecular dissociation is accompanied by the volumetric removal (i.e, ablative sublimation) of tissue and the production of low molecular weight gases 714, such as oxygen, nitrogen, carbon dioxide, hydrogen and methane. The short range of the accelerated charged particles 715 within the tissue confines the molecular dissociation process to the surface layer to minimize damage and necrosis to the underlying tissue 720.
During the process, the gases 714 will be aspirated through opening 609 and suction tube 611 to a vacuum source. In addition, excess electrically conductive fluid, and other fluids (e.g., blood) will be aspirated from the target site 700 to facilitate the surgeon's view. During ablation of the tissue, the residual heat generated by the current flux lines (typically less than 150°C), will usually be sufficient to coagulate any severed blood vessels at the site. If not, the surgeon may switch the power supply 428 into the coagulation mode by lowering the voltage to a level below the threshold for fluid vaporization, as discussed above. This simultaneous hemostasis results in less bleeding and facilitates the surgeon's ability to perform the procedure. Once the blockage has been removed, aeration and drainage are reestablished to allow the sinuses to heal and return to their normal function.
Figs. 18-22 illustrate another embodiment of the present invention. As shown in Fig. 18, an electrosurgical probe 800 includes an elongated shaft 801 which may be flexible or rigid, a handle 804 coupled to the proximal end of shaft 801 and an electrode support member 802 coupled to the distal end of shaft 801. As in previous embodiments, probe 800 includes an active loop electrode 803 and a return electrode 812 spaced proximally from active loop electrode 803. The probe 800 further includes a suction lumen 820 for aspirating excess fluids, bubbles, tissue fragments, and/ or products of ablation from the target site. As shown Figs. 22 and 18, suction lumen 820 extends through support member 802 to a distal opening 822, and extends through shaft 801 and handle 804 to an external connector 824 for coupling to a vacuum source. Typically, the vacuum source is a standard hospital pump that provides suction pressure to connector 824 and lumen 820.
As shown in Fig. 19, handle 804 defines an inner cavity 808 that houses the electrical connections 850 (discussed above), and provides a suitable interface for connection to an electrical connecting cable 22 (see Fig. 1). As shown in Fig. 21, the probe will also include a coding resistor 860 having a value selected to program different output ranges and modes of operation for the power supply. This allows a single power supply to be used with a variety of different probes in different applications (e.g., dermatology, cardiac surgery, neurosurgery, arthroscopy, etc.).
Electrode support member 802 extends from the distal end of shaft 801 (usually about 1 to 20 mm), and provides support for loop electrode 803 and a ring electrode 804 (see Fig. 22). As shown in Fig. 20, loop electrode 803 has first and second ends extending from the electrode support member 802. The first and second ends are each coupled to, or integral with, one or more connectors, e.g. , wires (not shown), that extend through the shaft of the probe to its proximal end for coupling to the high frequency power supply. The loop electrode usually extends about 0.5 to about 10 mm from the distal end of support member, preferably about 1 to 2 mm. Loop electrode 803 usually extends further away from the support member than the ring electrode 804 to facilitate ablation of tissue. As discussed below, loop electrode 803 is especially configured for tissue ablation, while the ring electrode 804 ablates tissue fragments that are aspirated into suction lumen 820.
Referring to Fig. 22, ring electrode 804 preferably comprises a tungsten or titanium wire having two ends 830, 832 coupled to electrical connnectors (not shown) within support member 802. The wire is bent to form one-half of a figure eight, thereby form a ring positioned over opening 822 of suction lumen 820. This ring inhibits passage of tissue fragments large enough to clog suction lumen 820. Moreover, voltage applied between ring electrode 804 and return electrode 812 provide sufficient energy to ablate these tissue fragments into smaller fragments that are then aspirated through lumen 820. In the presently preferred embodiment, ring electrode 804 and loop electrode 803 are electrically isolated from each other. However, these electrodes 804, 803 may be electrically coupled in some applications.
In yet another embodiment (not shown in the figures), the present invention comprises an electrosurgical probe having a suction lumen extending through the shaft, and one or more aspiration electrodes on the distal opening of the suction lumen. In this embodiment, the probe does not include separate ablation electrodes, such as a loop electrode or the like. Rather, the aspiration electrode(s) are designed to ablate tissue as the tissue is being aspirated into the lumen. In the preferred embodiment, the aspiration electrode(s) will include a conductive screen positioned over the distal opening of the suction lumen. The screen will have openings with sizes selected depending on the application. For example, if it is desired to increase the airflow through the suction lumen, the screen may have larger openings. However, if it is desired to ensure that tissue fragments do not clog the suction lumen, the openings may be smaller to ensure that the tissue is ablated into extremely small pieces prior to being pulled into the suction lumen. Another advantage of the present invention is the ability to precisely ablate layers of sinus tissue without causing necrosis or thermal damage to the underlying and surrounding tissues, nerves (e.g., the optic nerve) or bone. In addition, the voltage can be controlled so that the energy directed to the target site is insufficient to ablate bone or adipose tissue (which generally has a higher impedance than the target sinus tissue). In this manner, the surgeon can literally clean the tissue off the bone, without ablating or otherwise effecting significant damage to the bone.
Methods for treating air passage disorders according to the present invention will now be described. In these embodiments, an electrosurgical probe such as one described above can be used to ablate targeted masses including, but not limited to, the tongue, tonsils, turbinates, soft palate tissues (e.g. , the uvula), hard tissue and mucosal tissue. In one embodiment, selected portions of the tongue 714 are removed to treat sleep apnea. In this method, the distal end of an electrosurgical probe 490 is introduced into the patient's mouth 710, as shown in Fig. 17. An endoscope (not shown), or other type of viewing device, may also be introduced, or partially introduced, into the mouth 710 to allow the surgeon to view the procedure (the viewing device may be integral with, or separate from, the electrosurgical probe). The electrode terminals 104 are positioned adjacent to or against the back surface 716 of the tongue 714, and electrically conductive fluid is delivered to the target site, as described above. The power supply 428 is then activated to remove selected portions of the back of the tongue 714, as described above, without damaging sensitive structures, such as nerves, and the bottom portion of the tongue 714.
In another embodiment, the electrosurgical probe of the present invention can be used to ablate and/or contract soft palate tissue to treat snoring disorders. In particular, the probe is used to ablate or shrink sections of the uvula 720 without causing unwanted tissue damage under and around the selected sections of tissue. For tissue contraction, a sufficient voltage difference is applied between the electrode terminals 504 and the return electrode 512 to elevate the uvula tissue temperature from normal body temperatures (e.g., 37 °C) to temperatures in the range of 45°C to 90°C, preferably in the range from 60°C to 70°C. This temperature elevation causes contraction of the collagen connective fibers within the uvula tissue.
Other pharyngeal disorders can be treated according to the present invention. For example, hypopharyngeal diverticulum involves small pouches that form within the esophagus immediately above the esophageal opening. The sac of the pouch may be removed endoscopically according to the present invention by introducing a rigid esophagoscope, and isolating the sac of the pouch. The cricopharyngeus muscle is then divided, and the pouch is ablated according to the present invention. Tumors within the mouth and pharynx, such as hemangionmas, lymphangiomas, papillomas, lingual thyroid tumors, or malignant tumors, may also be removed according to the present invention. Other procedures of the present invention include removal of vocal cord polyps and lesions and partial or total laryngectomies. In the latter procedure, the entire larynx is removed from the base of the tongue to the trachea, if necessary with removal of parts of the tongue, the pharynx, the trachea and the thyroid gland.
Tracheal stenosis may also be treated according to the present invention. Acute and chronic stenoses within the wall of the trachea may cause coughing, cyanosis and choking. In another embodiment, the present invention comprises an electrified shaver or microdebrider. Powered instrumentation, such as microdebrider devices and shavers, has been used to remove polyps or other swollen tissue in functional endoscopic sinus surgery and synovial and meniscus tissue and articular cartilage I arthroscopic procedures. These powered instruments are disposable motorized cutters having a rotating shaft with a serrated distal tip for cutting and resecting tissue. The handle of the microdebrider is typically hollow, and it accommodates a small vacuum, which serves to aspirate debris. In this procedure, the distal tip of the shaft is endoscopically delivered into the patient's body cavity, and an external motor rotates the shaft and the serrated tip, allowing the tip to cut tissue, which is then aspirated through the instrument. While microdebriders and shavers have been promising, these devices suffer from a number of disadvantages. For one thing, these devices sever blood vessels within the tissue, usually causing profuse bleeding that obstructs the surgeon's view of the target site. Controlling this bleeding can be difficult since the vacuuming action tends to promote hemorrhaging from blood vessels disrupted during the procedure. In addition, the microdebrider or shaver often must be removed from the patient periodically to cauterize severed blood vessels, which lengthens the procedure. Moreover, the serrated edges and other fine crevices of the microdebrider and shaver can easily become clogged with debris, which requires the surgeon to remove and clean the microdebrider during the surgery, further increasing the length of the procedure. The present invention solves the above problems by providing one or more electrode terminals at the distal tip of the aspiration instrument to effect hemostasis of severed blood vessels at the target site. This minimizes bleeding to clear the surgical site, and to reduce postoperative swelling and pain. In addition, by providing an aspiration electrode on or near the suction lumen, as described above, the present invention avoids the problems of clogging inherent with these devices.
The systems of the present invention may include a bipolar arrangement of electrodes designed to ablate tissue at the target site, and then aspirate tissue fragments, as described above. Alternatively, the instrument may also include a rotating shaft with a cutting tip for cutting tissue in a conventional manner. In this embodiment, the electrode(s) serve to effect hemostasis at the target site and to reduce clogging of the aspiration lumen, while the rotating shaft and cutting tip do the bulk of tissue removal by cutting the tissue in a conventional manner. The system and method of the present invention may also be useful to efficaciously ablate (i.e. , disintegrate) cancer cells and tissue containing cancer cells, such as cancer on the surface of the epidermis, eye, colon, bladder, cervix, uterus and the like. The present invention's ability to completely disintegrate the target tissue can be advantageous in this application because simply vaporizing and fragmenting cancerous tissue may lead to spreading of viable cancer cells (i.e. , seeding) to other portions of the patient's body or to the surgical team in close proximity to the target tissue. In addition, the cancerous tissue can be removed to a precise depth while minimizing necrosis of the underlying tissue.
In addition, the active and return electrodes may both be located on a distal tissue treatment surface adjacent to each other. The active and return electrodes may be located in active/return electrode pairs, or one or more return electrodes may be located on the distal tip together with a plurality of electrically isolated electrode terminals. The proximal return electrode may or may not be employed in these embodiments. For example, if it is desired to maintain the current flux lines around the distal tip of the probe, the proximal return electrode will not be desired. Fig. 39 schematically illustrates a lipectomy procedure in the abdomen according to the present invention. Liposuction in the abdomen, lower torso and thighs according to the present invention removes the subcutaneous fat in these regions while leaving the fascial, neuro vascular and lymphatic network intact or only mildly compromised. As shown, access incisions 1200 are typically positioned in natural skin creases remote from the areas to be liposuctioned. In a conventional procedure, multiple incisions will be made to allow cross-tunneling, and the surgeon will manipulate the suction cannula in a linear piston-like motion during suction to remove the adipose tissue to avoid clogging of the cannula, and to facilitate separation of the fatty tissue from the remaining tissue. The present invention mostly solves these two problems and, therefore, minimizes the need for the surgeon to manipulate the probe in such a fashion.
In alternative embodiments, the high frequency voltage is sufficient to heat and soften or separate portions of the fatty tissue from the surrounding tissue. Suction is then applied from a vacuum source (not shown) through lumen 962 to aspirate or draw away the heated fatty tissue. A temperature of about 45 °C softens fatty tissue, and a temperature of about 50°C tends to liquefy ordinary fat. This heating and softening of the fatty tissue reduces the collateral damage created when the heated tissue is then removed through aspiration. Alternatively, the present invention may employ a combination of ablation through molecular dissociation, as described above, and heating or softening of the fatty tissue. In this embodiment, some of the fatty tissue is ablated in situ, while other portions are softened to facilitate removal through suction.
During the process, the gases will be aspirated through opening 1109 and suction tube 1111 to a vacuum source. In addition, excess electrically conductive fluid, and other fluids (e.g. , blood) will be aspirated from the target site to facilitate the surgeon's view. Applicant has also found that tissue fragments are also aspirated through opening 1109 into suction lumen and tube 1111 during the procedure. These tissue fragments are ablated or dissociated with loop electrodes 1040 with a similar mechanism described above. Namely, as electrically conductive fluid and tissue fragments are aspirated into loop electrodes 1040, these electrodes are activated so that high frequency voltage is applied to loop electrodes 1040 and return electrode 1012 (of course, the probe may include a different, separate return electrode for this purpose). The voltage is sufficient to vaporize the fluid, and create a plasma layer between loop electrodes 1040 and the tissue fragments so that portions of the tissue fragments are ablated or removed. This reduces the volume of the tissue fragments as they pass through suction lumen to minimize clogging of the lumen.
Fig. 24 illustrates a cervical liposuction procedure in the face and neck according to the present invention. As shown, the distal portion of the electrosurgical probe 1202 may be inserted in either submental or retroauricular incisions 1204 in the face and neck. In this procedure, the probe 1202 is preferably passed through a portion of the fatty tissue with the power supply 928 activated, but without suction to establish a plane of dissection at the most superficial level of desired fat removal. This plane of dissection allows a smooth, supple, redraping of the region after liposuction has been completed. If this "pretunneling" is not performed in this region, the cannula has a tendency to pull the skin inward, creating small pockets and indentations in the skin, which becomes evident as superficial irregularities after healing. Pretunneling also enables accurate, safe and proper removal of fat deposits while preserving a fine cushion of subdermal fat. The present invention may also be used to perform lipectomies in combination with face and neck lifts to facilitate the latter procedures. After the cervical liposuction is complete, the skin flaps are elevated in the temporal, cheek and lateral regions. The lateral neck skin flap dissection is greatly facilitated by the previous suction lipectomy in that region, and the medial and central skin flap elevation may be virtually eliminated.
1. A method for treating tissue at a target site comprising: introducing a distal end of an instrument to a target site on or within a patient's body; aspirating tissue from the target site through an aspiration lumen within the instrument; and applying high frequency voltage to an aspiration electrode coupled to the lumen, the high frequency voltage being sufficient to remove at least a portion of the tissue.
2. The method of claim 1 wherein the lumen has a distal opening and the aspiration electrode is positioned adjacent the distal opening.
3. The method of claim 1 wherein the lumen has a distal opening and the aspiration electrode is positioned across the distal opening.
4. The method of claim 1 wherein the lumen has a distal opening and the aspiration electrode is positioned within the lumen proximal to the distal opening.
5. The method of claim 1 further comprising: delivering electrically conductive fluid to the target site to substantially surround an active electrode with the electrically conductive fluid; and applying high frequency voltage between the active electrode and a return electrode, the high frequency voltage being sufficient to remove at least a portion of the tissue.
6. The method of claim 5 further comprising: generating tissue fragments during the tissue removal step; aspirating the tissue fragments through the lumen; and reducing the size of the tissue fragments by applying high frequency voltage between the aspiration electrode and the return electrode when the tissue fragments are adjacent the aspiration electrode.
7. The method of claim 5 wherein the aspiration and active electrodes are different electrodes.
8. The method of claim 5 wherein the aspiration and active electrodes are the same electrode.
9. The method of claim 1 wherein the tissue comprises a blockage within the nasal cavity or a paranasal sinus of the patient.
10. The method of claim 9 wherein the blockage is selected from the group comprising swollen tissue, turbinates, polyps, neoplasms and swollen mucus membranes lining an inner surface of the nasal cavity.
11. The method of claim 5 further comprising delivering the electrically conductive fluid past the return electrode to generate a current flow path between the return electrode and the aspiration electrode.
12. The method of claim 1 wherein the aspiration electrode comprises a single, active electrode at the distal end of the lumen.
13. The method of claim 1 wherein the aspiration electrode comprises a plurality of electrically isolated electrodes at the distal end of the aspiration lumen.
14. The method of claim 1 further comprising applying sufficient voltage to the aspiration electrode in the presence of the electrically conducting fluid to vaporize at least a portion of the fluid between the aspiration electrode and the tissue.
16. The method of claim 5 further comprising: drawing the tissue towards the aspiration electrode such that the aspiration electrode is in contact with, or close proximity to, the tissue in the presence of the electrically conductive fluid; and spacing the return electrode away from the tissue within the electrically conductive fluid such that the return electrode is not in contact with the tissue.
17. A method for treating tissue comprising: positioning a resection electrode adjacent tissue at a target site on or within a patient's body; applying high frequency voltage between the resection electrode and a return electrode and moving the resection electrode relative to the tissue to resect a tissue fragment from the tissue; and applying high frequency voltage between an ablation electrode and a return electrode, the voltage being sufficient to ablate the tissue fragment in situ.
18. The method of claim 17 wherein the ablation electrode and the resection electrode are the same electrode.
19. The method of claim 17 wherein the ablation electrode and the resection electrode are separate electrodes.
20. The method of claim 17 wherein the resection electrode comprises a loop extending distally from the distal end of an instrument shaft.
21. The method of claim 17 wherein the ablation electrode comprises a plurality of electrically independent electrodes on an instrument shaft spaced proximally from the resection electrode.
22. A method for treating tissue comprising: introducing an active electrode to a target site on or within a patient's body; applying a suction force to a tissue structure at the target site to draw the tissue structure to the active electrode; and after or during the applying suction step, applying high frequency voltage between the active electrode and a return electrode, the high frequency voltage being sufficient to ablate the tissue structure.
23. The method of claim 22 wherein the tissue structure comprises an elastic tissue structure.
24. The method of claim 22 wherein the tissue structure comprises synovial tissue within a joint.
25. An apparatus for applying electrical energy to tissue at a target site comprising: an electrosurgical instrument having a shaft with a proximal end portion, a distal end portion and an aspiration lumen therebetween, the aspiration lumen having a distal opening at or near the distal end portion of the shaft; a return electrode adapted to be electrically coupled to a high frequency power supply; and an aspiration electrode on the shaft in contact with the aspiration lumen; and a connector near the proximal end of the shaft for electrically coupling the aspiration electrode to a high frequency power supply;
26. The apparatus of claim 25 wherein the aspiration electrode is positioned adjacent the distal opening of the aspiration lumen.
27. The apparatus of claim 25 wherein the aspiration electrode is positioned across the distal opening of the aspiration lumen.
28. The apparatus of claim 25 wherein the aspiration electrode is positioned within the aspiration lumen proximal to the distal opening.
29. The apparatus of claim 25 wherein the aspiration electrode comprises a loop electrode extending across the distal opening of the aspiration lumen.
30. The apparatus of claim 25 wherein the aspiration electrode comprises two or more loop electrodes.
31. The apparatus of claim 25 wherein the aspiration electrode comprises one or more coiled electrodes.
32. The apparatus of claim 25 further comprising an ablation electrode electrically isolated from the aspiration electrode, wherein the return electrode is spaced proximally from the ablation electrode.
33. The apparatus of claim 25 further comprising an electrode array of electrically isolated ablation electrode terminals, the ablation electrode terminals being electrically isolated from the aspiration electrode.
34. The apparatus of claim 25 further comprising a fluid delivery element defining a fluid path in electrical contact with the return electrode and the electrode terminal to generate a current flow path between the return electrode and the electrode terminal.
35. The apparatus of claim 25 wherein the return electrode forms a portion of the shaft.
36. The apparatus of claim 25 further including an insulating member positioned between the return electrode and the electrode terminal, the return electrode being sufficiently spaced from the electrode terminal to minimize direct contact between the return electrode and a body structure at the target site when the electrode terminal is positioned in close proximity or in partial contact with the body structure.
37. An apparatus for applying electrical energy to a tissue structure at a target site comprising: an electrosurgical instrument having a shaft with a proximal end portion and a distal end portion; a loop electrode extending from the distal end portion of the shaft; an ablation electrode on the shaft spaced from the loop electrode; one or more return electrodes adapted for coupling to a high frequency power supply; and one or more connectors near the proximal end of the shaft for electrically coupling the loop and ablation electrodes to a high frequency power supply;
38. The apparatus of claim 37 further comprising an electrode array of electrically isolated ablation electrode terminals, the ablation electrode terminals being electrically isolated from the loop electrode.
39. The apparatus of claim 37 further comprising a fluid delivery element defining a fluid path in electrical contact with the return electrode and the electrode terminal to generate a current flow path between the return electrode and the electrode terminal.
40. The apparatus of claim 37 wherein the return electrode forms a portion of the shaft, and is spaced proximally from the loop electrode and the ablation electrode.
41. The apparatus of claim 37 further including an insulating member positioned between the return electrode and the loop and ablation electrodes, the return electrode being sufficiently spaced from the loop and ablation electrodes to minimize direct contact between the return electrode and a body structure at the target site when the loop and ablation electrodes are positioned in close proximity or in partial contact with the body structure.
42. A method for removing tissue from a target site comprising: positioning a distal end portion of an instrument adjacent tissue at a target site within a patient's body; aspirating at least a portion of the tissue through the instrument; and applying a high frequency voltage to an electrode on the distal end portion of the instrument to effect hemostasis of severed blood vessels at the target site.
43. The method of claim 42 further comprising applying sufficient high frequency voltage to the electrode to ablate at least a portion of the tissue prior to the aspirating step.
44. The method of claim 42 further comprising rotating a cutting tip to cut at least a portion of the tissue prior to the aspirating step.
45. A method for removing tissue from a target site comprising: positioning a distal end portion of an instrument adjacent tissue at a target site within a patient's body; applying a high frequency voltage to an electrode on the distal end portion of the instrument to apply energy to tissue at the target site, thereby converting the tissue into tissue fragments; aspirating at least a portion of the tissue fragments through the instrument.
46. The method of claim 45 further comprising applying a high frequency voltage to an electrode on the instrument to apply energy to the tissue fragments as the tissue fragments pass into the instrument.
47. A system for removing tissue at a target site comprising: an instrument having a shaft with a distal end portion, a proximal end portion and an active electrode on the distal end portion, wherein the distal end portion is sized for endoscopic delivery into a body cavity; a suction lumen within the instrument having a distal opening at the distal end portion and a proximal connector for coupling to a vacuum source; a return electrode; a high frequency power supply coupled to the return electrode and the electrode for applying a high frequency voltage difference therebetween sufficient to effect hemostasis of severed blood vessels at the target site.
48. The system of claim 47 wherein the high frequency voltage difference is sufficient to ablate at least a portion of the tissue at the target site.
49. The system of claim 47 further comprising a rotating shaft and a cutting tip at the distal end portion for cutting tissue at the target site.
50. A method for removing fatty tissue underlying a patient's epidermis comprising: positioning an electrode terminal and a return electrode in close proximity to a target region of fatty tissue; applying a high frequency voltage difference between the electrode terminal and the return electrode to modify the fatty tissue; and 0 during the applying voltage step, aspirating a portion of the fatty tissue from the target region.
51. The method of claim 50 wherein the high frequency voltage difference is sufficient to soften at least a portion of the fatty tissue. 5
52. The method of claim 50 wherein the high frequency voltage difference is sufficient to liquefy at least a portion of the fatty tissue.
53. The method of claim 50 wherein the high frequency voltage o difference is sufficient to ablate at least a portion of the fatty tissue in situ.
54. The method of claim 50 further comprising delivering electrically conducting fluid to the target site, and contacting the electrically conducting fluid with the return electrode to provide a current flow path from the electrode terminal, through the 5 electrically conducting fluid, and to the return electrode.
55. The method of claim 50 further comprising positioning the return electrode proximal to the electrode terminal to induce current flow from the electrode terminal away from the target site. 0
56. The method of claim 50 further comprising directing electrically conducting fluid along a fluid path past the electrode terminal and the return electrode to generate the current flow path between the return electrode and the electrode terminal.
57. The method of claim 50 wherein further comprising applying a sufficient high frequency voltage difference between the return electrode and the electrode terminal to remove fatty tissue through molecular dissociation or disintegration.
58. A method for performing a lipectomy comprising: positioning an electrode terminal in close proximity to a target region of fatty tissue underlying the epidermis; and applying a sufficient high frequency voltage to the electrode terminal to volumetrically remove fatty tissue in situ without applying suction to the fatty tissue.
59. An apparatus for removing fatty tissue underlying the epidermis comprising: a shaft having proximal and distal end portions and an electrode terminal on the distal end portion, the distal end portion being sized for introduction through a percutaneous penetration in the patient's epidermis; a return electrode on the shaft spaced from the electrode terminal; a power supply coupled to the electrode terminal and the return electrode for applying a sufficient high frequency voltage difference between the electrode and the return electrode to modify fatty tissue underlying the epidermis; and a suction lumen positioned adjacent the electrode terminal for aspirating the modified fatty tissue from the patient.
60. The apparatus of claim 59 further comprising an aspiration electrode in contact with the aspiration lumen and electrically coupled to the power supply;
61. The apparatus of claim 60 wherein the suction lumen is coupled to the shaft and the aspiration electrode is positioned adjacent the distal opening of the suction lumen.
PCT/US1998/022327 1995-06-07 1998-10-20 Systems and methods for tissue resection, ablation and aspiration WO1999020185A1 (en)
US6299797P true 1997-10-23 1997-10-23
US08/990,374 1997-12-15
US08/990,374 US6109268A (en) 1995-06-07 1997-12-15 Systems and methods for electrosurgical endoscopic sinus surgery
US09/010,381 US5941722A (en) 1997-01-21 1998-01-21 Crimp connector
US09/162,110 US6461350B1 (en) 1995-11-22 1998-09-28 Systems and methods for electrosurgical-assisted lipectomy
US09/162,110 1998-09-28
US60/062,997 1998-09-28
US09/010,381 1998-09-28
JP2000516596A JP2003527875A (en) 1997-10-23 1998-10-20 Ablating tissue, ablation and apparatus and method for sucking
EP19980955041 EP1026996B1 (en) 1997-10-23 1998-10-20 Systems for tissue resection, ablation and aspiration
DE1998638555 DE69838555T2 (en) 1997-10-23 1998-10-20 Systems for tissue resection, ablation and extraction
AU11940/99A AU1194099A (en) 1997-10-23 1998-10-20 Systems and methods for tissue resection, ablation and aspiration
WO1999020185A1 true WO1999020185A1 (en) 1999-04-29
ID=27486003
PCT/US1998/022327 WO1999020185A1 (en) 1995-06-07 1998-10-20 Systems and methods for tissue resection, ablation and aspiration
EP (2) EP1880686B1 (en)
JP (1) JP2003527875A (en)
AT (1) AT375126T (en)
AU (1) AU1194099A (en)
DE (1) DE69838555T2 (en)
WO (1) WO1999020185A1 (en)
EP1289438A1 (en) * 2000-06-09 2003-03-12 Arthrocare Corporation Electrosurgical apparatus and methods for ablating tissue
1998-10-20 AT AT98955041T patent/AT375126T/en not_active IP Right Cessation
1998-10-20 EP EP07118068.1A patent/EP1880686B1/en not_active Expired - Lifetime
1998-10-20 DE DE1998638555 patent/DE69838555T2/en not_active Expired - Lifetime
1998-10-20 WO PCT/US1998/022327 patent/WO1999020185A1/en active IP Right Grant
1998-10-20 JP JP2000516596A patent/JP2003527875A/en active Pending
1998-10-20 EP EP19980955041 patent/EP1026996B1/en not_active Expired - Lifetime
1998-10-20 AU AU11940/99A patent/AU1194099A/en not_active Abandoned
See also references of EP1026996A4 *
EP1289438A4 (en) * 2000-06-09 2005-09-07 Arthrocare Corp Electrosurgical apparatus and methods for ablating tissue
EP1026996A4 (en) 2001-09-12
EP1880686B1 (en) 2017-06-21
AT375126T (en) 2007-10-15
EP1026996B1 (en) 2007-10-10
EP1880686A2 (en) 2008-01-23
EP1880686A3 (en) 2011-01-26
DE69838555D1 (en) 2007-11-22
EP1026996A1 (en) 2000-08-16
AU1194099A (en) 1999-05-10
DE69838555T2 (en) 2008-07-24
JP2003527875A (en) 2003-09-24
DE69928370T2 (en) 2006-08-03 System and methods for electrosurgical tissue treatment in the presence of electrically conductive fluids
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