Method and Apparatus for Vascular Tissue Sealing with Reduced Energy Consumption

[0001] 1. Technical Field

[0002] The present disclosure relates to electrosurgical instruments used for open and endoscopic surgical procedures for sealing or fusing tissue. More particularly, the present disclosure relates to a bipolar forceps for sealing vessels, vascular tissues and soft tissues by perforating vessels and/or tissue and applying energy in the vicinity of the perforated area to reduce energy consumption and facilitate extraction of collagen and elastin during an electrosurgical procedure.

[0003] 2. Background of the Related Art

[0004] Open or endoscopic electrosurgical forceps utilize both mechanical clamping action and electrical energy to effect hemostasis. The electrode of each opposing jaw member is charged to a different electric potential such that when the jaw members grasp tissue, electrical energy can be selectively transferred through the tissue. A surgeon can cauterize, coagulate/desiccate and/or simply reduce or slow bleeding, by controlling the intensity, frequency and duration of the electrosurgical energy applied between the electrodes and through the tissue.

[0005] Certain surgical procedures require more than simply cauterizing tissue and rely on the combination of clamping pressure, electrosurgical energy and gap distance to “seal” tissue, vessels and certain vascular bundles. More particularly, vessel sealing or tissue sealing utilizes a unique combination of radiofrequency (RF) energy, clamping pressure and precise control of gap distance (i.e., distance between opposing jaw members when closed about tissue) to effectively seal or fuse tissue between two opposing jaw members or sealing plates. Vessel or tissue sealing is more than “cauterization”, which involves the use of heat to destroy tissue (also called “diathermy” or “electrodiathermy”). Vessel sealing is also more than “coagulation”, which is the process of desiccating tissue wherein the tissue cells are ruptured and dried. “Vessel sealing” is defined as the process of liquefying the collagen, elastin and ground substances in the tissue so that the tissue reforms into a fused mass with significantly-reduced demarcation between the opposing tissue structures.

[0006] Existing electrosurgical forceps utilize a pair of jaw members having metal electrodes to grasp and hold tissue during a sealing procedure. The metal electrodes deliver RF energy to tissue and the electric current conducted by the tissue releases heat that eventually seals the tissue. This approach may be inefficient and result in unnecessary energy consumption. For instance, even if tissue between jaw members contains a single vessel, traditional RF energy-based tissue sealing instruments would seal the entire volume of tissue between the jaws that would lead to energy loss as well as increasing the possibility of collateral damage. Further, because electrodes are made from metal, which has high heat conductivity, such electrodes may be responsible for significant heat loss. Additionally, although grasping and holding tissue facilitates tissue damage and extracting and mixing of elastin and collagen, a sufficient amount of elastin and collagen is not released.

[0007] In an embodiment of the present disclosure, an end effector assembly is provided. The end effector assembly includes a pair of opposing jaw members configured to grasp tissue therebetween. Each of the opposing jaw members includes a non conducting tissue contact surface and an energy delivering element configured to perforate the tissue to create an opening, extract elastin and collagen from the tissue and denaturize the elastin and the collagen in the vicinity of the opening.

[0008] In another embodiment of the present disclosure, an electrosurgical instrument for sealing tissue is provided. The electrosurgical instrument may include a housing, a handle assembly and an end effector assembly. The end effector assembly includes a pair of opposing jaw members configured to grasp tissue therebetween. Each of the opposing jaw members includes a non conducting tissue contact surface and an energy delivering element configured to perforate the tissue to create an opening, extract elastin and collagen from the tissue and denaturize the elastin and the collagen in the vicinity of the opening.

[0009] In yet another embodiment of the present disclosure another electrosurgical instrument for sealing tissue is provided. The electrosurgical instrument may include a pair of opposing shafts with each shaft having a handle at the proximal end of the shaft. The instrument may also include an end effector assembly including a pair of opposing jaw members attached at a distal end of the pair of opposing shafts wherein the opposing jaw members move from a first position to a second position by moving the pair of opposing shafts relative to one another. Each of the opposing jaw members includes a non conducting tissue contact surface and an energy delivering element configured to perforate the tissue to create an opening, extract elastin and collagen from the tissue and denaturize the elastin and the collagen in the vicinity of the opening.

[0010] The energy delivering element includes a post electrode configured to apply energy to the tissue to perforate the tissue and to extract elastin and collagen from the tissue and a ring electrode to denaturize the elastin and the collagen in the vicinity of the opening. The post electrode and ring electrode may apply radio frequency energy, optical energy or a combination of both radiofrequency energy and optical energy.

[0011] In yet another embodiment of the present disclosure, a method for sealing tissue using an end effector assembly having a pair of opposing jaw member wherein each jaw member has at least one energy delivering element is provided. The method includes grasping tissue between the pair of opposing jaw members, applying a first energy from the energy delivering element to perforate the tissue to create an opening in the tissue and to extract elastin and collagen from the tissue and applying a second energy from the energy delivering element to denaturize the elastin and the collagen in the vicinity of the opening in the tissue.

[0019] Particular embodiments of the present disclosure are described hereinbelow with reference to the accompanying drawings; however, the disclosed embodiments are merely examples of the disclosure and may be embodied in various forms. Well-known functions or constructions are not described in detail to avoid obscuring the present disclosure in unnecessary detail. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a basis for the claims and as a representative basis for teaching one skilled in the art to variously employ the present disclosure in virtually any appropriately detailed structure. Like reference numerals may refer to similar or identical elements throughout the description of the figures.

[0020] Electromagnetic energy is generally classified by increasing frequency or decreasing wavelength into radio waves, microwaves, infrared, visible light, ultraviolet, X-rays and gamma-rays. As used herein, the term “microwave” generally refers to electromagnetic waves in the frequency range of 300 megahertz (MHz) (3×10⁸ cycles/second) to 300 gigahertz (GHz) (3×10¹¹ cycles/second). As used herein, the term “RF” generally refers to electromagnetic waves having a lower frequency than microwaves. The terms “tissue” and “vessel” may be used interchangeably since it is believed that the present disclosure may be employed to seal and cut tissue or seal and cut vessels utilizing the same principles described herein.

[0021] As will be described in more detail below with reference to the accompanying figures, the present disclosure is directed to the use energy delivering elements having post electrodes and circle electrodes to reduce the consumption of energy during a vessel sealing procedure as well as increase the release of elastin and collagen from vessel walls.

[0022] Referring now to FIGS. 1 and 2, FIG. 1 depicts a bipolar forceps 10 for use in connection with endoscopic surgical procedures and FIG. 2 depicts an open forceps 100 contemplated for use in connection with traditional open surgical procedures. For the purposes herein, either an endoscopic instrument or an open instrument may be utilized with the electrode assembly described herein. Different electrical and mechanical connections and considerations may apply to each particular type of instrument; however, the aspects with respect to the electrode assembly and its operating characteristics remain generally consistent with respect to both the open or endoscopic designs.

[0023] FIG. 1 shows a bipolar forceps 10 for use with various endoscopic surgical procedures and generally includes a housing 20, a handle assembly 30, a rotating assembly 80, a switch assembly 70 and an electrode assembly 105 having opposing jaw members 110 and 120 that mutually cooperate to grasp, seal and divide tubular vessels and vascular tissue. The jaw members 110 and 120 are connected about pivot pin 19, which allows the jaw members 110 and 120 to pivot relative to one another from the first to second positions for treating tissue. More particularly, forceps 10 includes a shaft 12 that has a distal end 16 dimensioned to mechanically engage the electrode assembly 105 and a proximal end 14 that mechanically engages the housing 20. The shaft 12 may include one or more known mechanically-engaging components that are designed to securely receive and engage the electrode assembly 105 such that the jaw members 110 and 120 are pivotable relative to one another to engage and grasp tissue therebetween.

[0024] The proximal end 14 of shaft 12 mechanically engages the rotating assembly 80 to facilitate rotation of the electrode assembly 105. In the drawings and in the descriptions that follow, the term “proximal”, as is traditional, will refer to the end of the forceps 10 that is closer to the user, while the term “distal” will refer to the end that is further from the user. Details relating to the mechanically cooperating components of the shaft 12 and the rotating assembly 80 are described in commonly-owned U.S. patent application Ser. No. 10/460,926, now U.S. Pat. No. 7,156,846, entitled “VESSEL SEALER AND DIVIDER FOR USE WITH SMALL TROCARS AND CANNULAS” filed on Jun. 13, 2003.

[0025] Handle assembly 30 includes a fixed handle 50 and a movable handle 40. Fixed handle 50 is integrally associated with housing 20 and handle 40 is movable relative to fixed handle 50 to actuate the opposing jaw members 110 and 120 of the electrode assembly 105 as explained in more detail below. Movable handle 40 and switch assembly 70 are of unitary construction and are operatively connected to the housing 20 and the fixed handle 50 during the assembly process. Housing 20 is constructed from two component halves 20a and 20b, which are assembled about the proximal end of shaft 12 during assembly. Switch assembly is configured to selectively provide electrical energy to the electrode assembly 105.

[0026] As mentioned above, electrode assembly 105 is attached to the distal end 16 of shaft 12 and includes the opposing jaw members 110 and 120. Movable handle 40 of handle assembly 30 imparts movement of the jaw members 110 and 120 from an open position wherein the jaw members 110 and 120 are disposed in spaced relation relative to one another, to a clamping or closed position wherein the jaw members 110 and 120 cooperate to grasp tissue therebetween.

[0027] Referring now to FIG. 2, an open forceps 100 includes a pair of elongated shaft portions 112a and 112b each having a proximal end 114a and 114b, respectively, and a distal end 116a and 116b, respectively. The forceps 100 includes jaw members 120 and 110 that attach to distal ends 116a and 116b of shafts 112a and 112b, respectively. The jaw members 110 and 120 are connected about pivot pin 119, which allows the jaw members 110 and 120 to pivot relative to one another from the first to second positions for treating tissue. The electrode assembly 105 is connected to opposing jaw members 110 and 120 and may include electrical connections through or around the pivot pin 119. Examples of various electrical connections to the jaw members are shown in commonly-owned U.S. patent application Ser. Nos. 10/474,170, 10/284,562 10/472,295, 10/116,944 and 10/179,863, now U.S. Pat. Nos. 7,582,087, 7,267,677, 7,101,372, 7,083,618 and 7,101,371 respectively.

[0028] Each shaft 112a and 112b includes a handle 117a and 117b disposed at the proximal end 114a and 114b thereof that each define a finger hole 118a and 118b, respectively, therethrough for receiving a finger of the user. As can be appreciated, finger holes 118a and 118b facilitate movement of the shafts 112a and 112b relative to one another, which, in turn, pivot the jaw members 110 and 120 from the open position wherein the jaw members 110 and 120 are disposed in spaced relation relative to one another to the clamping or closed position wherein the jaw members 110 and 120 cooperate to grasp tissue therebetween. A ratchet 130 may be included for selectively locking the jaw members 110 and 120 relative to one another at various positions during pivoting.

[0029] More particularly, the ratchet 130 includes a first mechanical interface 130a associated with shaft 112a and a second mating mechanical interface associated with shaft 112b. Each position associated with the cooperating ratchet interfaces 130a and 130b holds a specific, i.e., constant, strain energy in the shaft members 112a and 112b, which, in turn, transmits a specific closing force to the jaw members 110 and 120. The ratchet 130 may include graduations or other visual markings that enable the user to easily and quickly ascertain and control the amount of closure force desired between the jaw members 110 and 120.

[0030] As best seen in FIG. 2, forceps 100 also includes an electrical interface or plug 200 that connects the forceps 100 to a source of electrosurgical energy, e.g., an electrosurgical generator similar to generator 500 shown in FIG. 1. Plug 200 includes at least two prong members 202a and 202b that are dimensioned to mechanically and electrically connect the forceps 100 to the electrosurgical generator 500 (See FIG. 1). An electrical cable 210 extends from the plug 200 and securely connects the cable 210 to the forceps 100. Cable 210 is internally divided within the shaft 112b to transmit electrosurgical energy through various electrical feed paths to the electrode assembly 105.

[0031] One of the shafts, e.g. 112b, includes a proximal shaft connector/flange 140 that is designed to connect the forceps 100 to a source of electrosurgical energy such as an electrosurgical generator 500. More particularly, flange 140 mechanically secures electrosurgical cable 210 to the forceps 100 such that the user may selectively apply electrosurgical energy as needed.

[0032] As will be described below with reference to FIGS. 3 and 4, each jaw member 110 and 120 includes a non-conductive tissue contacting surface 303 disposed along substantially the entire longitudinal length thereof (e.g., extending substantially from the proximal to distal end of each respective jaw member 110 and 120). The non-conductive tissue contacting surface 303 may be made from an insulative material, such as ceramic due to its hardness and inherent ability to withstand high temperature fluctuations. Alternatively, the non-conductive tissue contacting surface 303 may be made from a material or a combination of materials having a high Comparative Tracking Index (CTI) in the range of about 300 to about 600 volts. Examples of high CTI materials include nylons and syndiotactic polystryrenes such as QUESTRA® manufactured by DOW Chemical. Other materials may also be utilized either alone or in combination, e.g., Nylons, Syndiotactic-polystryrene (SPS), Polybutylene Terephthalate (PBT), Polycarbonate (PC), Acrylonitrile Butadiene Styrene (ABS), Polyphthalamide (PPA), Polymide, Polyethylene Terephthalate (PET), Polyamide-imide (PAI), Acrylic (PMMA), Polystyrene (PS and HIPS), Polyether Sulfone (PES), Aliphatic Polyketone, Acetal (POM) Copolymer, Polyurethane (PU and TPU), Nylon with Polyphenylene-oxide dispersion and Acrylonitrile Styrene Acrylate. Preferably, the non-conductive tissue contacting surface 303 is dimensioned to securingly engage and grasp tissue and may include serrations (not shown) or roughened surfaces to facilitate approximating and grasping tissue.

[0033] Non-conductive tissue contacting surface 303 includes at least one energy delivering element 305 that includes a post electrode 306 and a ring electrode 307. Although shown as a circular-shape, ring electrode 307 may assume any other annular or enclosed configuration or alternatively partially enclosed configuration such as a C-shape arrangement. The post electrode 306 is concentrically centered within ring electrode 307. Each energy delivering element 305 on jaw member 110 has a corresponding energy delivering element 305 on jaw member 120 such that when the jaw members 110 and 120 are closed about tissue, electrosurgical energy flows from post electrode 306 on jaw member 110 to post electrode 306 on jaw member 120 or from ring electrode 307 on jaw member 110 to ring electrode 307 on jaw member 120. Energy delivering elements 305 may be arranged on tissue contacting surface 303 in a chess-like pattern as shown in FIG. 3 or any other suitable pattern.

[0034] FIGS. 5 through 8 depict different stages of the sealing procedure according to an embodiment of the present disclosure. During a sealing procedure, a surgeon grasps and pressurizes vessels 400 using jaw members 110 and 120 causing vessel walls 402 to move closer to each other and come in contact with each other. RF energy is applied between post electrode 306 on jaw member 110 and a corresponding post electrode 306 on jaw member 120 to perforate tissue 400, thereby creating an opening 404 (FIG. 5). After perforation, elastin and collagen is released from space 403 between vessel walls 401 and 402. The released elastin and collagen fills opening 404. RF energy is applied in the vicinity of opening 404 by ring electrodes 307 (FIG. 6), thereby releasing heat that denaturizes elastin and collagen in opening 404 and forming a rivet 405 (FIGS. 7 and 8).

[0035] As shown in FIG. 8, the electrical paths are connected to the plurality of energy delivering elements 305 in jaw members 110 and 120. More particularly, the first electrical path 510 (i.e., an electrical path having a first electrical potential) from generator 500 is connected to each post electrode 306 and each ring electrode 307 of jaw member 510. The second electrical path 520 (i.e., an electrical path having a second electrical potential) from generator 500 is connected to each post electrode 306 and each ring electrode 307 of jaw member 120. The electrical paths 510 and 520 do not encumber the movement of the jaw members 110 and 120 relative to one another during the manipulation and grasping of tissue 400. Likewise, the movement of the jaw members 110 and 120 do not unnecessarily strain the electrical paths 510 and 520 or their respective connections.

[0036] The above described perforation of tissue may be performed by conducting RF energy between post electrodes 306 of jaw members 110 and 120 as described above or by a mechanical perforator or application of optical energy (e.g., by a laser). Energy applied for denaturizing elastin and collagen may be RF energy as described above or optical energy. In another embodiment, perforation and application of energy to denaturize elastin and collagen may be performed substantially simultaneously.

[0037] Generator 500 may also control activation of energy delivery elements 305 according to a routine stored in the generator or provided by the user. For instance, generator 500 may activate a single pair of opposing energy delivery elements 305 or multiple pairs of opposing energy delivery elements 305. The multiple pairs of opposing energy delivery elements may be activated according to a predetermined sequence or simultaneously.

[0038] The non-conductive tissue contacting surfaces 303 may include one or more stop members (not shown) configured to limit the movement of the two opposing jaw members 110 and 120 relative to one another to form a gap therebetween. It is envisioned that the stop members may be disposed on the non conductive tissue contacting surface 303 of one or both of the jaw members 110 and 120 depending upon a particular purpose or to achieve a particular result

[0039] While several embodiments of the disclosure have been shown in the drawings and/or discussed herein, it is not intended that the disclosure be limited thereto, as it is intended that the disclosure be as broad in scope as the art will allow and that the specification be read likewise. Therefore, the above description should not be construed as limiting, but merely as exemplifications of particular embodiments. The claims can encompass embodiments in hardware, software, or a combination thereof. Those skilled in the art will envision other modifications within the scope and spirit of the claims appended hereto.