An electrosurgical instrument including an elongated shaft and a non-conductive handle. The shaft defines a proximal section, a distal section, and an internal lumen extending from the proximal section. The distal section forms an electrically conductive tip and defines at least one passage for distributing fluid. Further, the shaft is adapted to be transitionable from a straight state to a first bent state. The shaft is capable of independently maintaining the distinct shapes associated with the straight state and the first bent state. The handle is rigidly coupled to the proximal section of the shaft. With this in mind, an exterior surface of the shaft distal the handle and proximal the distal section is electrically non-conductive. In one preferred embodiment, the shaft is comprised of an elongated electrode body surrounded by an electrical insulator.

BACKGROUND OF THE INVENTION

The present invention relates to an electrosurgical instrument and related system for use in surgical ablation or electrocautery procedures. More particularly, it relates to a fluid-assisted electrocautery instrument designed to be indifferent to rotational orientation and including a bendable shaft capable of independently maintaining a desired shape.

A wide variety of surgical procedures involve ablation or cauterization of selected tissue. For example, hemorrhoid or varicose vein removal can be accomplished by ablating the tissue in question. Additionally, tissue ablation and/or cauterization is commonly employed for the surgical treatment of cardiac arrhythmia, and in particular atrial fibrillation. In general terms, cardiac arrhythmia relates to disturbances in the heart's electrical system that causes the heart to beat irregularly, too fast or too slow. Irregular heartbeats, or arrhythmia, are caused by physiological or pathological disturbances in the discharge of electrical impulses from the sinoatrial node, in the transmission of the signal through heart tissue, or spontaneous, unexpected electrical signals generated within the heart. One type of arrhythmia is tachycardia, which is an abnormal rapidity of heart action. There are several different forms of atrial tachycardia, including atrial fibrillation and atrial flutter. With atrial fibrillation, instead of a single beat, numerous electrical impulses are generated by depolarizing tissue at one or more locations in the atria (or possible other locations). These unexpected electrical impulses produce irregular, often rapid heartbeats in the atrial muscles and ventricles. As to the location of the depolarizing tissue, it is generally agreed that the undesired electrical impulses often originate in the left atrial region of the heart, and in particular in one (or more) of the pulmonary veins extending from the left atrium. With this in mind, and as an alternative to drug therapy, ablation of the abnormal tissue or accessory pathway responsible for the atrial fibrillation has proven highly viable.

Regardless of exact application, ablation or cauterization of tissue is typically achieved by applying a destructive energy source to the target tissue, including radiofrequency electrical energy, direct current electrical energy, and the like. The ablative energy source is provided by an electrode that is otherwise placed in contact with the target tissue. For some treatments, the electrode can be formed as a part of a catheter that is otherwise sub-cutaneously delivered to the target site. While relatively non-invasive, catheter-based treatments present certain obstacles to achieving precisely located, complete ablation lesion patterns due to the highly flexible nature of the catheter itself, the confines of the surgical site; etc.

A highly viable alternative device is the hand-held electrosurgical instrument. As used herein, the term “electrosurgical instrument” includes a hand-held instrument capable of ablating tissue or cauterizing tissue, but does not include a catheter-based device. The instrument is relatively short (as compared to a catheter-based device), and rigidly couples the electrode tip to the instrument's handle that is otherwise held and manipulated by the surgeon. The rigid construction of the electrosurgical instrument requires direct, open access to the targeted tissue. Thus, for treatment of atrial fibrillation via an electrosurgical instrument, it is desirable to gain access to the patient's heart through one or more openings in the patient's chest (such as a sternotomy, a thoracotomy, a small incision and/or a port). In addition, the patient's heart may be opened through one or more incisions, thereby allowing access to the endocardial surface of the heart.

Once the target site (e.g., right atrium, left atrium, epicardial surface, endocardial surface, etc.) is accessible, the surgeon positions the electrode tip of the electrosurgical instrument at the target site. The tip is then energized, ablating (or for some applications, cauterizing) the contacted tissue. A desired lesion pattern is then created (e.g., portions of a known “Maze” procedure) by moving the tip in a desired fashion along the target site. In this regard, the surgeon can easily control positioning and movement of the tip, as the electrosurgical instrument is rigidly constructed and relatively short (in contrast to a catheter-based ablation technique).

Electrosurgical instruments, especially those used for the treatment of atrial fibrillation, have evolved to include additional features that provide improved results for particular procedures. For example, U.S. Pat. No. 5,897,553, the teachings of which are incorporated herein by reference, describes a fluid-assisted electrosurgical instrument that delivers a conductive solution to the target site in conjunction with electrical energy, thereby creating a “virtual” electrode. The virtual electrode technique has proven highly effective in achieving desired ablation while minimizing collateral tissue damage. Other electrosurgical instrument advancements have likewise optimized system performance. However, a common characteristic associated with available electrosurgical instruments is a “designed-in” directional orientation. That is to say, electrosurgical devices, and especially those used for atrial fibrillation treatment procedures, are curved along a length thereof, as exemplified by the electrosurgical instrument of U.S. Pat. No. 5,897,553. In theory, this permanent curved feature facilitates the particular procedure (or lesion pattern) for which the electrosurgical instrument is intended. Unfortunately, however, the actual lesion pattern formation technique and/or bodily structure may vary from what is expected, so that the curve is less than optimal. Additionally, the pre-made curve may be well suited for one portion of a particular procedure (e.g., right atrium ablation pattern during the Maze procedure), but entirely inapplicable to another portion (e.g., left atrium ablation during the Maze procedure). As a result, the electrosurgical instrument design may actually impede convenient use by a surgeon.

Electrosurgical instruments continue to be highly useful for performing a variety of surgical procedures, including surgical treatment of atrial fibrillation. While certain advancements have improved overall performance, the accepted practice of imparting a permanent curve or other shape variation into the instrument itself may impede optimal usage during a particular procedure. Therefore, a need exists for an electrosurgical instrument that, as initially presented to a surgeon, is indifferent to rotational orientation, and further is capable of independently maintaining a number of different shapes as desired by the surgeon.

SUMMARY OF THE INVENTION

One aspect of the present invention relates to an electrosurgical instrument including an elongated shaft and a non-conductive handle. The shaft defines a proximal section, a distal section, and an internal lumen extending from the proximal section. The distal section forms an electrically conductive rounded tip and defines at least one passage fluidly connected to the lumen. This passage distributes fluid from the internal lumen outwardly from the shaft. Further, the shaft is adapted to be transitionable from a straight state to a bent state, preferably a number of different bent states. In this regard, the shaft is capable of independently maintaining the distinct shapes associated with the straight state and the bent state(s). The non-conductive handle is rigidly coupled to the proximal section of the shaft. With this in mind, an exterior surface of the shaft distal the handle and proximal the distal section is electrically non-conductive. In one preferred embodiment, the shaft is comprised of an elongated electrode body and an electrical insulator. The electrode body defines the distal section and is rigidly coupled to the handle. The electrical insulator surrounds at least a portion of the electrode body proximal the distal section such that the tip is exposed.

During use, and when first presented to a surgeon, the shaft is in the straight state such that the electrosurgical instrument is effectively indifferent to a rotational orientation when the handle is grasped by the surgeon. Subsequently, the surgeon can bend the shaft to a desired shape (i.e., the bent state) being most useful for the particular electrosurgical procedure. During the procedure, a conductive fluid is directed onto the target site from the internal lumen via the passage. The tip then energizes the dispensed fluid, causing tissue ablation or cauterization.

Yet another aspect of the present invention relates to an electrosurgical system including an electrosurgical instrument, a source of conductive fluid, and an energy source. The electrosurgical instrument includes an elongated shaft and a non-conductive handle. The shaft defines a proximal section, a distal section, and an internal lumen extending from the proximal section. The distal section forms an electrically conductive rounded tip and defines at least one passage fluidly connected to the lumen. Further, the shaft is adapted to be transitionable from, and independently maintain a shape in, a straight state and a bent state. The handle is rigidly coupled to the proximal section of the shaft. An exterior surface of the shaft distal the handle and proximal the distal section is electrically non-conductive. The source of conductive fluid is fluidly connected to the internal lumen. Finally, the energy source is electrically connected to the tip. During use, the electrosurgical instrument can be presented to the target site in either the straight state or the bent state. Regardless, the shaft independently maintains the shape associated with the selected state. Conductive fluid is delivered from the conductive fluid source to the internal lumen, and is then distributed to the target site via the passage. The energy source is activated, thereby energizing the electrode tip. This action, in turn, energizes the distributed conductive fluid, causing desired tissue ablation or cauterization. In one preferred embodiment, the electrosurgical instrument further includes an indifferent, or non-ablating, electrode (such as a grounding patch). The indifferent electrode is electrically connected to the energy source and it is placed separately from the target site. For example, the indifferent electrode may be placed on the back of the patient.

Yet another aspect of the present invention relates to a method of performing an electrosurgical procedure. The method includes providing an electrosurgical instrument including an elongated shaft and, a handle. In this regard, the shaft defines a proximal section, a distal section, and an internal lumen. The proximal section is rigidly coupled to the handle, whereas the distal section forms a round tip. Finally, the internal lumen extends from the proximal section and is in fluid communication with at least one passage formed in the distal section. An exterior surface of the shaft distal the handle and proximal the distal section is electrically non-conductive. The shaft is provided in an initial straight state that otherwise defines a linear axis. The shaft is then bent to a first bent state in which a portion of the shaft is deflected relative to the linear axis. In this regard, the shaft independently maintains a shape of the first bent state. The tip is then positioned at a tissue target site. In one preferred embodiment, an indifferent electrode is placed in contact with the patient. Conductive fluid is dispensed from the passage to the tissue target site via the internal lumen. Finally, energy is applied to the dispensed fluid by energizing the tip. Subsequently, the energized tip and conductive fluid ablates or cauterizes tissue at the tissue target site. In one embodiment, the tissue target site comprises tissue of a patient's heart, and the method further includes accessing the tissue target site through one or more openings in the patient's chest. In another embodiment, after a first lesion pattern is formed at a first tissue target site, the shaft is bent to a second shape and the procedure repeated to effectuate a second lesion pattern at a second tissue target site.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

One preferred embodiment of an electrosurgical system10in accordance with the present invention is shown inFIG. 1. The system10is comprised of an electrosurgical instrument12, a fluid source14, a power source16, and an indifferent electrode18. The various components are described in greater detail below. In general terms, however, the fluid source14is fluidly connected to the electrosurgical instrument12. Similarly, the power source16is electrically connected to the electrosurgical instrument12and to the indifferent electrode18. During use, conductive fluid is delivered from the fluid source14to a distal portion of the electrosurgical instrument12. The distributed fluid is energized by the electrosurgical instrument12via the power source16. The so-energized conductive fluid is capable of forming a virtual electrode, which is capable of ablating or cauterizing contacted tissue.

The electrosurgical instrument12includes a handle20and a shaft22. As described in greater detail below, the shaft22is rigidly coupled to the handle20, and is transitionable from a straight state (as illustrated inFIG. 1) to a bent state (for example as shown inFIGS. 5B and 5C). In this regard, the shaft22independently maintains the shape associated with the particular state (i.e., straight or bent).

The handle20is preferably made of a sterilizable, rigid, and non-conductive material, such as a polymer or ceramic. Suitable polymers include rigid plastics, rubbers, acrylics, nylons, polystyrenes, polyvinylchlorides, polycarbonates, polyurethanes, polyethylenes, polypropylenes, polyamides, polyethers, polyesters, polyolefins, polyacrylates, polyisoprenes, fluoropolymers, combinations thereof or the like. Further, the handle20is ergonomically designed to comfortably rest within a surgeon's hand (not shown). To this end, the handle20may include a grip portion24that is circular in cross section. This configuration facilitates grasping of the handle20, and thus of the electrosurgical instrument12, at any position along the grip portion24regardless of an overall rotational orientation of the electrosurgical instrument12. That is to say, due to the circular, cross-sectional shape of the grip portion24, the electrosurgical instrument12can be rotated to any position relative to a central axis A, and still be conveniently grasped by the surgeon. In an even more preferred embodiment, the grip portion24defines a gradual, distally increasing diameter that provides an orientation feature to help a surgeon identify where along the length of the electrosurgical instrument12he or she is grasping. For example, if the surgeon grasps the electrosurgical instrument12out of his visual sight during a medical procedure, the surgeon may identify based on the grip portion's24diameter where along the instrument he has grasped. Finally, the grip portion24is preferably formed of a low durometer polymer. Suitable polymers include low durometer plastics, rubbers, silicones, acrylics, nylons, polystyrenes, polyvinylchlorides, polycarbonates, polyurethanes, polyethylenes, polypropylenes, polyamides, polyethers, polyesters, polyolefins, polyacrylates, polyisoprenes, fluoropolymers, combinations thereof or the like. The grip portion24alternatively may be a sponge-like or foam-like material, such as an open-cell material or a closed-cell material.

Regardless of exact configuration, the handle20forms or encompasses one or more central lumens (not shown). The lumen(s) provides a pathway for a line or tubing26from the fluid source14to the shaft22, as well as a pathway for a line or wiring28from the power source16to the shaft22. In this regard,FIG. 2illustrates the electrosurgical instrument12with the handle20removed. The tubing26from the fluid source14(FIG. 1) is shown as extending to, and being fluidly connected with, the shaft22. Similarly, the line28from the power source16(FIG. 1) is shown as extending to, and being electrically connected with, the shaft22.

Returning toFIG. 1, the shaft22is an elongated, relatively rigid component defining a proximal section40and a distal section42. The distal section42terminates in an electrically conductive tip44. As described in greater detail below, the tip44is rounded, defining a uniform radius of curvature. With this configuration, the tip44is, similar to the handle20, indifferent to rotational orientation of the electrosurgical device12. That is to say, regardless of how a surgeon (not shown) grasps the handle20(i.e., the rotational position of the handle20relative to the central axis A), a profile of the tip44in all directions (e.g., in front of the surgeon's thumb position, behind the surgeon's thumb position, etc.) is always the same so that the tip44is readily maneuvered along tissue (not shown) in any direction. To this end, the rounded shape facilitates sliding movement of the tip44along the tissue.

With additional reference toFIG. 3, the shaft22defines an internal lumen50that is fluidly connected to the tubing26. In this way, the internal lumen50delivers fluid from the fluid source14to the distal section42.

With additional reference toFIG. 4A, the distal section42preferably forms a plurality of passages52that are fluidly connected to the internal lumen50. The passages52are formed at or proximal the tip44and preferably are uniformly located relative to a circumference of the distal section42. For example, in one preferred embodiment, two sets54a,54bof the passages52are provided, in addition to a central passage54cat the tip44. The passages52associated with each of the two sets54a,54bare circumferentially aligned, and uniformly spaced approximately 90° from one another. For example, in one embodiment, the passages52are uniformly located on a hemispherical portion of the tip44as described below. Alternatively, other numbers and locations are acceptable. By preferably uniformly spacing the passages52, however, the distal section42is further formed to be indifferent to rotational orientation of the electrosurgical instrument12. In other words, regardless of the rotational position of the electrosurgical instrument12and/or the direction of tip44movement, the passages52provide a relatively uniform disbursement of conductive fluid about the tip44via the internal lumen50. In an alternative embodiment, the tip44is made of a porous material, that allows fluid to pass from the internal lumen50through the tip44.

In another alternative embodiment, and as best shown inFIG. 4B, at least some of the passages52(for example, the passage set54b) are located along a generally hemispherical portion56of the tip44. This one preferred design facilitates a more complete delivery of liquid to a target site (not shown) that is otherwise contacted by the tip44. In general terms, during an electrosurgical procedure, it is important that a sufficient volume of irrigation fluid is continually provided to the electrode tip44/target site tissue interface to reduce the opportunity for tissue charring or desiccation. Previous electrosurgical designs positioned all of the passages52(except for the central passage54c) along a cylindrical portion58of the tip44(as opposed to the generally hemispherical portion56). With this prior design, where a particular surgical procedure required that the tip44be oriented such that the passages52are “below” the electrode tip44/target site tissue interface, some or all of the irrigation liquid otherwise dispensed from the passages52(other than the central passage54c) might flow away from the electrode tip44(or back along the shaft22). The one preferred passage configuration ofFIG. 4Bovercomes this concern, as all of the irrigation liquid distributed from the passages54bon the generally hemispherical portion56will be delivered to the electrode tip44/target site tissue interface due to surface tension at the interface.

Regardless of passage location, a further preferred feature of the shaft22is a malleable or shapeable characteristic. In particular, and with additional reference toFIGS. 5A-5C, the shaft22is configured to be transitionable from an initial straight state (FIG. 5A) to a bent or curved state (FIGS. 5B and 5C). In this regard, the electrosurgical instrument12, and in particular the shaft22, is initially presented to a surgeon (not shown) in the straight state ofFIG. 5A, whereby the shaft22assumes a straight shape defining the central axis A. In the straight state, the shaft22is indifferent to rotational orientation, such that the electrosurgical instrument12can be grasped at any rotational position and the tip44will be located at an identical position. Further, as previously described, a profile of the tip44is also uniform or identical at any rotational position of the electrosurgical instrument12. Subsequently, depending upon the constraints of a particular electrosurgical procedure, the shaft22can be bent relative to the central axis A. Two examples of an applicable bent state or shape are provided inFIGS. 5B and 5C. In a preferred embodiment, the shaft22can be bent at any point along a length thereof, and can be formed to include multiple bends or curves. Regardless, the shaft22is configured to independently maintain the shape associated with the selected bent shape. That is to say, the shaft22does not require additional components (e.g., pull wires, etc.) to maintain the selected bent shape. Further, the shaft22is constructed such that a user can readily re-shape the shaft22back to the straight state ofFIG. 5Aand/or other desired bent configurations. Notably, the shaft22is configured to relatively rigidly maintain the selected shape such that when a sliding force is imparted onto the shaft22as the tip44dragged across tissue, the shaft22will not overtly deflect from the selected shape.

In one preferred embodiment, the above-described characteristics of the shaft22are achieved by forming the shaft22to include an elongated electrode body60and an electrical insulator covering62as shown inFIGS. 1 and 3. The electrode body60defines the proximal section40and the distal section42of the shaft22. To this end, the proximal section40of the electrode body60is rigidly coupled to the handle20. The insulator62covers a substantial portion of the electrode body60, preferably leaving the distal section42exposed. In particular, the insulator62is positioned to encompass an entirety of the electrode body60distal the handle20and proximal the distal section42(and in particular, proximal the passages52and the tip44).

In one preferred embodiment, the electrode body60is a tube formed of an electrically conductive, malleable material, preferably stainless steel, however other materials such as, for example, nitinol can be used. The passages52are preferably drilled, machined, laser cut, or otherwise formed through at least a portion of the electrode body60. The passages or openings52may comprise circular holes, semi-circular holes, oval holes, rectangular slots, and/or other configurations for allowing fluid to pass.

The insulator62is formed of one or more electrically non-conductive materials, and serves to electrically insulate the encompassed portion of the electrode body60. Multiple layers of electrically non-conductive materials can help prevent the likelihood of forming an electrical short along the length of the electrode body60due to a mechanical failure of one of the non-conductive materials. In this regard, the insulator62is preferably comprised of two materials having considerably different mechanical properties, e.g., a silicone and a fluoropolymer. In one preferred embodiment, a silicone tubing material is overlaid with a heat shrink fluoropolymer tubing material. Alternatively, the insulator62may be one or more non-conductive coatings applied over a portion of the electrode body60. In addition to being non-conductive, the insulator62is preferably flexible and conforms to the electrode body60such that the insulator62does not impede desired shaping and re-shaping of the electrode body60as previously described.

It will be understood that the preferred construction of the shaft22to include the elongated electrode body60and the insulator62is but one available configuration. Alternatively, the shaft22can be constructed of an electrode material forming the tip44, and a rigid or malleable, non-conductive tube rigidly connecting the tip44to the handle20. The non-conductive tube can include one or more metal conductors, such as straight wire and/or windings for electrically connecting the tip44to the power source16. Along these same lines, another alternative embodiment includes forming the tip44from an inherently porous material. For example, the tip44may comprise one or more porous polymers, metals, or ceramics. Further, the tip44may be coated with non-stick coatings such as PTFE or other types of coatings such as biological coatings. Another alternative embodiment includes construction of the shaft22to include one or more metal conductors, such as straight wire and/or windings inside a rigid or malleable non-conductive polymer tube. The non-conductive polymer tube includes one or more openings, such as holes, slots or pores (preferably corresponding with the passages52previously described), which allow conductive fluid to exit the polymer tube. The conductive fluid creates a virtual electrode via electrically connecting the one or more metal conductors to the target tissue. Conversely, the shaft22may comprise a polymer tube having one or more openings, such as holes, slots or pores (preferably corresponding with the passages52previously described), placed inside an electrical conductor, such as a metal tube having one or more openings, such as holes, slots or pores, or a metal winding having a spacing that allows conductive fluid to pass through, to control conductive fluid delivery through the electrical conductor. Finally, the insulator62may cover a portion of the metal tube or windings.

With respect to the above-described alternative embodiments, connection between the elongated tube and the separate tip44can be accomplished in a variety of manners. Once again, the elongated tube can comprise a conductive or non-conductive material(s), such as metal(s) or plastic(s). The elongated tube can be connected to the tip44via a variety of coupling techniques, including, for example, welding, laser welding, spin welding, crimping, gluing, soldering and press fitting. Alternatively, the distal end of the elongated tube and the tip44can be configured to threadably engage one another and/or mechanical engagement member(s) (e.g., pins, screws, rivets, etc.) can be employed. In another embodiment, the elongated tube is rigidly coupled to the tip44. In yet another embodiment, the tip44can be moveably coupled to the elongated tube, whereby the tip44can be moved and/or locked relative to the elongated tube. For example, the tip44can be coupled to the elongated tube via one or more joints or hinges. The joints or hinges can be ball joints and/or joints that include a pin. To this end, a pin-type joint can be configured to allow the tip44to swivel relative to the elongated tube. Further, the joint(s) can be configured to move and lock into position. In addition, one or more actuators (e.g., knobs, buttons, levers, slides, etc.) can be located on, for example, the handle20(FIG. 1) for actuating the joint(s). With the above in mind,FIG. 6illustrates a portion of an alternative embodiment shaft22′ including a tip44′ moveably coupled to an elongated tube63by a pin64.

Returning toFIG. 1, the electrosurgical instrument12preferably includes a coupling member65for rigidly coupling the shaft22to the handle20. The coupling member65can comprise one or more polymers, plastics, and/or rubbers. For example, the coupling member65can comprise one or more silicones, acrylics, nylons, polystyrenes, polyvinylchlorides, polycarbonates, polyurethanes, polyethylenes, polypropylenes, polyamides, polyethers, polyesters, polyolefins, polyacrylates, polyisoprenes, fluoropolymers, combinations thereof or the like. The coupling member65preferably forms a drip edge66to interrupt, divert and prevent any flow of liquid from the tip44, down the shaft22and onto the handle20, thereby preventing any electrically conducting fluid from contacting the surgeon.

Regardless of exact construction of the electrosurgical instrument12, the fluid source14maintains a supply of conductive fluid (not shown), such as an energy-conducting fluid, an ionic fluid, a saline solution, a saturated saline solution, a Ringer's solution, etc. It is preferred that the conductive fluid be sterile. The conductive fluid can further comprise one or more contrast agents, and/or biological agents such as diagnostic agents, therapeutic agents or drugs. The biological agents may be found in nature (naturally occurring) or may be chemically synthesized.

As a point of reference, during use the conductive fluid serves to electrically couples the electrode tip44of electrosurgical instrument12to the tissue to be treated, thereby lowering the impedance at the target site. The conductive fluid may create a larger effective electrode surface. The conductive fluid can help cool the tip44of the electrosurgical instrument12. The conductive fluid may keep the surface temperature of the tip44below the threshold for blood coagulation, which may clog the electrosurgical instrument12. The conductive fluid may also cool the surface of the tissue thereby preventing over heating of the tissue which can cause popping, desiccation, burning and/or charring of the tissue. The burning and/or charring of the tissue may also clog the electrosurgical instrument12. Therefore, use of the conductive fluid may reduce the need to remove a clogged electrosurgical instrument for cleaning or replacement. Further, charred tissue has high impedance, thereby making the transfer of RF energy difficult, and may limit the ability of the electrosurgical instrument12to form a transmural lesion. The delivery of conductive fluid during the electrosurgical process may help create deeper lesions that are more likely to be transmural. Transmurality is achieved when the full thickness of the target tissue is ablated. Continuous conductive fluid flow may ensure that a conductive fluid layer between the tip44and the contours of the tissue to be treated is created.

In one preferred embodiment, the fluid source14includes a fluid reservoir, such as a bag, a bottle or a canister, for maintaining a supply of conductive fluid previously described. With this configuration, the fluid reservoir can be positioned at an elevated location, thereby gravity feeding the conductive fluid to the electrosurgical instrument12, or the fluid reservoir may be pressurized, thereby pressure feeding the conductive fluid to the electrosurgical instrument12. For example, a pressure cuff may be placed around a flexible bag, such as an IV bag, of conductive fluid, thereby pressure feeding the conductive fluid to the electrosurgical instrument12. Alternatively, the fluid source14can include, and/or be connected to, a manual or electrical pump (not shown), such as an infusion pump, a syringe pump, or a roller pump. The fluid source14can further comprise one or more orifices or fluid regulators, (e.g., valves, fluid reservoirs, conduits, lines, tubes and/or hoses) to control flow rates. The conduits, lines, tubes, or hoses may be flexible or rigid. For example, a flexible hose may be used to communicate fluid from the fluid source14to the electrosurgical instrument12, thereby allowing electrosurgical instrument12to be easily manipulated by a surgeon. Alternatively, the fluid source14can be directly connected to, or incorporated into, the handle20. For example, a pressurized canister of conductive fluid may be directly connected to the handle20. Further, the fluid source14can comprise a syringe, a squeeze bulb and/or some other fluid moving means, device or system.

In another embodiment, the fluid source14further includes a surgeon-controlled switch (not shown). For example, a switch may be incorporated in or on the fluid source14or any other location easily and quickly accessed by a surgeon for regulation of conductive fluid delivery. The switch may be, for example, a hand switch, a foot switch, or a voice-activated switch comprising voice-recognition technologies.

In yet another alternative embodiment, the fluid source14includes a visual and/or audible signaling device (not shown) used to alert a surgeon to any change in the delivery of conductive fluid. For example, a beeping tone or flashing light can be used to alert the surgeon that a change has occurred in the delivery of conductive fluid.

The power source16is of a type known in the art, and is preferably a radio-frequency (RF) generator. The generator can be powered by AC current, DC current or it can be battery powered either by a disposable or re-chargeable battery. The generator can incorporate a controller (not shown) or any suitable processor to control power levels delivered to the electrosurgical instrument12based on information supplied to the generator/controller.

The above-described electrosurgical system10, including the electrosurgical instrument12, is useful for a number of different tissue ablation and cauterization procedures. For example, the electrosurgical system10can be used to remove hemorrhoids or varicose veins or stop esophageal bleeding to name but a few possible uses. Additionally, the electrosurgical system10is highly useful for the surgical treatment of cardiac arrhythmia, and in particular treatment of atrial fibrillation via ablation of atrial tissue. To this end, the Maze procedure, such as described inCardiovascular Device Update, Vol. 1, No. 4, July 1995, pp. 2-3, the teachings of which are incorporated herein by reference, is a well known technique, whereby lesion patterns are created along specified areas of the atria. The Maze III procedure, a modified version of the original Maze procedure, has been described inCardiac Surgery Operative Technique, Mosby Inc., 1997, pp. 410-419, the teachings of which are incorporated herein by reference. In an effort to reduce the complexity of the surgical Maze procedure, a modified Maze procedure was developed as described inThe Surgical Treatment of Atrial Fibrillation, Medtronic Inc., 2001, the teachings of which are incorporated herein by reference.

FIG. 7Adepicts use of the electrosurgical system10, and in particular the electrosurgical instrument12, performing a portion of the Maze procedure. In particular,FIG. 7Aincludes a representation of a heart70with its left atrium72exposed. Prior to use, the electrosurgical instrument12is provided to the surgeon (not shown) with the shaft22in the initial straight state (FIG. 1). The surgeon then evaluates the constraints presented by the tissue target site74and the desired lesion pattern to be formed. Following this evaluation, the surgeon determines an optimal shape of the shaft22most conducive to achieving the desired ablation/lesion pattern. With this evaluation in mind, the surgeon then transitions or bends the shaft22from the initial straight state to the bent state illustrated inFIG. 7A. Once again, the shaft22is configured to independently maintain this selected shape. The shaft22can be bent by hand and/or by use of bending jigs or tools.

Once the desired shape of the shaft22has been achieved, the tip44is directed to the tissue target site74. An indifferent electrode (18inFIG. 1, but not shown inFIG. 7A) is placed in contact with the patient. Conductive fluid from the fluid source14(FIG. 1) is delivered to the tissue target site74via the internal lumen50(FIG. 3), the passages52and/or the porous tip44. Once sufficient fluid flow has been established, the tip44is energized via the power source16(FIG. 1). The tip44, in turn, energizes the distributed fluid, thereby creating a virtual electrode that ablates contacted tissue. The surgeon then slides or drags the tip44along the left atrium70tissue, thereby creating a desired lesion pattern78, as best shown inFIG. 7B. In this regard, the rigid coupling between the shaft22and the handle20allows the tip44to easily be slid along the atrial tissue via movement of the handle20. Once the desired lesion pattern78has been completed, energization of the tip44is discontinued, as well as delivery of conductive fluid from the fluid source14. If additional lesion patterns are required, the surgeon again evaluates the target tissue site, and re-forms the shaft22accordingly.

Notably, the shaft22need not necessarily be bent to perform a tissue ablation procedure. Instead, the tip44can be drug across the target site tissue74with the shaft22in the initial straight state. In this regard, because the shaft22is straight and the handle20(FIG. 1) is preferably circumferentially uniform, the electrosurgical instrument12does not have a discernable drag direction (as compared to the shaft22being bent or curved, whereby the curve inherently defines a most appropriate drag direction).

In addition to the one exemplary procedure described above, the electrosurgical instrument12may be positioned and used, for example, through a thoracotomy, through a sternotomy, percutaneously, transveneously, arthroscopically, endoscopically, for example, through a percutaneous port, through a stab wound or puncture, through a small incision, for example, in the chest, in the groin, in the abdomen, in the neck or in the knee, or in combinations thereof. It is also contemplated that the electrosurgical instrument12may be used in other ways, for example, in open-chest surgery on a heart in which the sternum is split and the rib cage opened with a retractor.

The electrosurgical system10, and in particular the electrosurgical instrument12, described above with respect toFIG. 1is but one acceptable configuration in accordance with the present invention. That is to say, the system10and/or the instrument12can assume other forms and/or include additional features while still providing an electrosurgical instrument having a shaft that independently maintains varying shapes associated with a straight state and a bent state, and is indifferent to rotational orientation in the straight state.

For example, the electrosurgical instrument12can include a surgeon-controlled switch. For example, a switch may be incorporated in or on the electrosurgical instrument12or any other location easily and quickly accessed by the surgeon for regulation of the electrosurgical instrument12by the surgeon. The switch may be, for example, a hand switch, a foot switch, or a voice-activated switch comprising voice-recognition technologies. One or more switches may be incorporated into the grip portion24of the electrosurgical instrument12. For example, a switch may be used to control conductive fluid delivery and/or power delivery. A switch incorporated into the grip portion24may be a switch, such as a membrane switch, encompassing the entire circumference of the electrosurgical instrument12, thereby effectively being indifferent to a rotational orientation when the surgeon grasps the handle. That is to say, due to the cross-sectional shape of the switch, the electrosurgical instrument12may be rotated to any position relative to a central axis A, and still be conveniently controlled by the surgeon.

Alternatively, a hand switch connected to the electrosurgical instrument12, but not incorporated into the electrosurgical instrument12, may be used. For example, a switch designed to be worn by a surgeon, for example on a surgeon's thumb, may be used to activate and/or deactivate the electrosurgical instrument12. A switch may be incorporated into a cuff or strap that is placed on or around the thumb or finger of a surgeon. Alternatively, a switch may be designed to fit comfortably in a surgeon's palm.

One or more visual and/or audible signals used to alert a surgeon to the completion or resumption of ablation, conductive fluid delivery and/or power delivery, for example, may be incorporated into the electrosurgical instrument12. For example, a beeping tone or flashing light that increases in frequency as the ablation period ends or begins may be used. Alternatively or in addition, an indicator light otherwise located on the electrosurgical instrument can be inductively coupled to the power source16and adapted such that when power is being delivered to the electrosurgical instrument12, the light is visible to the surgeon or other users.

An alternative embodiment electrosurgical instrument112is provided inFIGS. 8A and 8D. The electrosurgical instrument112is highly similar to the electrosurgical instrument12(FIG. 1) previously described, and includes a handle120, a shaft122, a fluid supply tube126and wiring128. The shaft122is virtually identical to the shaft22(FIG. 1) previously described, and forms a tip124having passages (not shown) fluidly connected to an internal lumen (not shown). Further, the shaft122is adapted to be bendable from a straight state (FIG. 8A) to multiple bent states (one of which is illustrated inFIG. 8B), with the shaft122independently maintaining a shape associated with the particular state. Similar to previous embodiments, the fluid supply tube126fluidly connects the fluid source14(FIG. 1) to the shaft122, whereas the wiring128electrically connects the power source16(FIG. 1) to the shaft122.

The handle120varies from the handle20(FIG. 1) previously described in that the handle120does not define a curved outer surface. Instead, the handle120is hexagonal in transverse cross-section. This alternative configuration is, however, indifferent to rotational orientation when grasped by a user, thereby promoting the preferred ease of use feature previously described. Notably, the handle120can alternatively be formed to a variety of other symmetrical transverse cross-sectional shapes (e.g., octagonal, etc.).

In yet another alternative embodiment, the electrosurgical system10(FIG. 1) further includes a controller (not shown) that can also gather and process information from the electrosurgical instrument12,120, fluid source14and/or one or more sensors or sensing elements such as temperature sensors or probes. The information supplied to or gathered by the controller can be used to adjust, for example, conductive fluid delivery, power levels, and/or energization times. For example, a temperature sensor coupled to the controller can be located in the distal section42(FIG. 1) of the electrosurgical instrument12. The temperature sensor can be a thermocouple element that measures the temperature of the tip44rather than the temperature of the conductive fluid or the temperature of the tissue being ablated. Alternatively, the temperature sensor can be a thermocouple element that measures the temperature of the conductive fluid or a thermocouple element that measures the temperature of the tissue being ablated. When the ablation site is being irrigated with a conductive fluid, the temperature of the tissue may differ to some degree from the temperature of the conductive fluid or the temperature of the tip44.

Heat, 1.0 kcal/g, is required to raise the temperature of water, present at the ablation site, by 1° C. However, due to the unique chemical structure of the water molecule, additional heat is required for water to change phase from the liquid phase to the gaseous phase. If the temperature at the ablation site exceeds 100° C., water will change phase, boil and may result in an audible “steam pop” within the tissue. This pop may damage and even rupture the tissue. Therefore, it is desirable to prevent the ablation site from getting to hot. In addition, to form a permanent ablation lesion the temperature of the tissue at the ablation site must be elevated to approximately 50° C. or greater. For these reasons, it is desirable to use one or more temperature-sensing elements such as, for example, thermocouples, thermisters, temperature-sensing liquid crystals, temperature-sensing chemicals, thermal cameras, and/or infrared (IR) fiber optics, to monitor the temperature of the ablation site during the ablation procedure.

With the above in mind,FIGS. 9A-9Cdepict a portion of an alternative embodiment electrosurgical device140, and in particular a distal section142thereof. The electrosurgical instrument140is highly similar to previous embodiments, and includes a shaft144terminating at an electrically conductive tip146having passages148formed therein that are fluidly connected to an internal lumen150. Further, the electrosurgical instrument140includes a temperature probe160for monitoring tissue temperature of the tissue being ablated. The temperature probe160is placed at the tip146. A ring of insulation material162may be used to electrically and thermally isolate the temperature probe160from the electrically conductive tip146. The preferred central placement of the temperature probe160at the tip146allows the temperature probe160to directly contact a tissue surface in a number of orientations. The preferred insulating material162helps to prevent the thermal mass of the tip146and the RF energy from interfering with temperature information otherwise provided by the probe160.

An alternative embodiment for monitoring temperature includes an IR optical fiber system. As shown inFIGS. 10A-10D, an alternative embodiment electrosurgical instrument190may include an optical fiber192for monitoring temperature based on IR. The optical fiber192can be positioned adjacent a tip194otherwise defined by the instrument190(FIGS. 10A and 10B) or within the tip194itself (FIGS. 10C and 10D).

The above-described temperature-sensing elements160,192can be used to adjust, for example, conductive fluid delivery, power levels, and/or ablation times. Temperature-sensing elements can be coupled to a visual and/or audible signal used to alert a surgeon to a variety of thermal conditions. For example, a beeping tone or flashing light that increases in frequency as temperature of the tissue, the conductive fluid and/or electrosurgical instrument is increased and/or as temperature exceeds a predetermined amount can be used.

Along these same lines, the above-mentioned controller can incorporate one or more switches to facilitate regulation of the various components of the electrosurgical system10(FIG. 1) by the surgeon. One example of such a switch is a foot pedal. The switch can also be, for example, a hand switch as described above, or a voice-activated switch comprising voice-recognition technologies. The switch can be incorporated in or on one of the surgeon's instruments, such as surgical site retractor, e.g., a sternal or rib retractor, or the electrosurgical instrument12(FIG. 1), or any other location easily and quickly accessed by the surgeon. The controller can also include a display or other means of indicating the status of various components to the surgeon, such as a numerical display, gauges, a monitor display or audio feedback.

Finally, a visual and/or audible signal used to alert a surgeon to the completion or resumption of ablation, sensing, monitoring, and/or delivery of conductive fluid can be incorporated into the controller. For example, a beeping tone or flashing light that increases in frequency as the ablation or electrocautery period ends or begins can be provided.

In yet another alternative embodiment, the fluid source14can be slaved to the electrosurgical instrument12, the power source16and/or one or more sensors (as previously described). For example, the fluid source14can be designed to automatically stop or start the delivery of conductive fluid during the delivery of RF energy. Conversely, the delivery of RF energy may be slaved to the delivery of conductive fluid. That is the delivery of RF energy to the tip44would be coupled to the delivery of conductive fluid to the tip44. If the flow of conductive fluid to the tip44were stopped, the RF energy delivered to the tip44would also automatically stop. For example, a switch responsive to the delivery of conductive fluid to the tip44for controlling RF energy delivery to the tip44can be incorporated into the electrosurgical instrument12. The switch can be located, for example, within the shaft22or the handle20of electrosurgical instrument12.

With the above in mind,FIG. 11illustrates a portion of an alternative embodiment electrosurgical instrument200including a shaft202extending from a handle (not shown). The shaft202includes an electrically conductive tip204and a malleable, non-conductive tube206rigidly connecting the tip204to the handle. An electrically conducting switch piston208is located within the non-conductive tube206. The conducting switch piston208is electrically coupled to the power source16(FIG. 1). The conducting switch piston208is movably held in a non-contacting position relative to the tip204by a spring or other elastic means (not shown). As conductive fluid is delivered, a pressure develops behind an orifice210of the conducting switch piston208. The size and shape of the orifice210is selected based on expected fluid delivery rates and pressures. When the necessary pressure or force to over come the spring retaining pressure or force is reached, the conducting switch208travels distally towards the tip204, thereby making an electrical contact with the tip204. Other means can be used to slave the delivery of power to the tip204of the electrosurgical instrument200to the delivery of conductive fluid to the tip204of the electrosurgical instrument200. For example, the controller can incorporate one or more switches to facilitate the regulation of RF energy based on the delivery of conductive fluid.

In yet another embodiment, and with general reference toFIG. 1, the electrosurgical instrument12, the fluid source14and/or the power source16can be slaved to a robotic system or a robotic system may be slaved to the electrosurgical instrument12, the fluid source14and/or the power source16.

The electrosurgical system, and in particular the electrosurgical instrument, of the present invention provides a marked improvement over previous designs. The handle and shaft are configured to be indifferent to rotational orientation when initially presented to a surgeon. Subsequently, the surgeon can conveniently shape or bend the shaft so as to provide a shape most conducive to forming the lesion pattern required by the particular surgical procedure. In this regard, the shaft independently maintains the selected shape throughout the particular electrosurgical procedure. Subsequently, the shaft can be re-shaped back to a straight configuration, or to any other desired curvature.

Although the invention has been described above in connection with particular embodiments and examples, it will be appreciated by those skilled in the art that the invention is not necessarily so limited, and that numerous other embodiments, examples, uses, modifications and departures from the embodiments, examples and uses are intended to be encompassed by the claims attached hereto. The entire disclosure of each patent and publication cited herein is incorporated by reference, as if each such patent or publication were individually incorporated by reference herein.