IMPROVEMENTS IN ELECTROHYDRAULIC LITHOTRIPSY

Abstract: Apparatus for fracturing hard deposits such as urinary and biliary calculi and arteriosclerotic plaque in the human body. An elongate guide member (50) having an apertured hollow (52) adjacent its distal end and an optic viewing system (120) preferably terminating adjacent its distal end is inserted within the body with the distal end positioned adjacent the target. A working fluid (56) is supplied to the hollow, and an electric spark is discharged within the hollow from an external energy source (84) for generating pulse waves in the working fluid. The resulting pulse waves express working fluid from the hollow to impinge on the target. Makeup fluid is supplied and the spark repeated. The apparatus also may advantageously be employed for dilating narrowing in hollow internal structures in the body. In a preferred embodiment of the invention, the apparatus includes a pair of electrodes (20) having rectangular cross sections, and having flat faces of rectangular configuration confronting one another. An insulating member (18) is interposed between the electrodes and spaces them apart a predetermined distance. A shield (38) surrounds and extends beyond the electrode and the insulating member to inhibit radial propagation of shockwave energy while enhancing axial propagation thereof.

Description: 1 IMPROVEMENTS IN ELECTROHYDRAULIC LITHOTRIPSY 2 3 The present invention relates to a system for 4 fracturing hard formations in the body, and more 5 specifically, to a method and apparatus for fracturing 6 deposits such as urinary and biliary calculi as well as 7 arteriosclerotic plaque in the body. 8 Calciferous and similar deposits occur in body fluid 9 passages of various types. Of particular interest are 10 urinary and biliary calculi as well as arteriosclerotic 11 plaque. 12 Electrohydraulic lithotripsy and laser lithotripsy 13 systems frequently are used to fragment urinary and 14 biliary stones. Both systems utilize plasma-induced 15 stress waves to fragment calculi. Electrohydraulic 16 lithotripsy produces a plasma through an electrical 17 discharge (spark). Electrohydraulic lithotripsy systems 18 are relatively inexpensive. However, with 19 electrohydraulic lithotripsy systems, there is a potential 20 for thermal damage to healthy tissues surrounding the 21 target deposit. With laser lithotripsy, a plasma is 22 produced when a portion of the laser energy is absorbed by 23 the stone. However, laser lithotripsy systems are 24 expensive. Also, in the case of laser lithotripsy, the 25 sharp laser delivery fiber may cause damage if 26 inadvertently jabbed into healthy tissue. 27 In an article entitled "Effects of Shielded or 28 Unshielded Laser and Electrohydraulic Lithotripsy on 29 Rabbit Bladder" published in the Journal of Urology, Vol. 30 148, Pages 857-860, April 1990, there is disclosed a t \ 31 plasma shield for use with either a pulsed laser 32 lithotripter or an electrohydraulic lithotripter. As 33 described therein, the hollow shield is provided using a 34 hollow spring fitted with a metal end cap. The pulsed 35 laser source or pulsed electrical voltage source located 36 in the flexible guide provides a pulse of energy in the vicinity of the metal end cap to produce a rapid vapor expansion that causes the metal end cap to undergo a pulse-like movement as the vapor expands against the fluid medium of the passage to impart a high-velocity jack- hammer type impact on the target deposit. While the plasma shield impact device as described in the aforesaid publication offers the advantages of protecting surrounding healthy tissue from direct laser /EEL spark, and also eliminates inadvertent puncturing of healthy tissue by a sharply pointed laser delivery fiber, the metal end cap is prone to fragmentation, resulting in the formation of metal fines in the body cavity. The present invention provides an apparatus for selectively fracturing hard deposits such as urinary and biliary calculi and atherosclerotic plaque which overcomes the aforesaid and other disadvantages of the prior art. In accordance with one aspect of the present invention there is provided an electrohydraulic lithotripsy system in which a shock wave is generated directly in a fluid mass adjacent the target deposit, and the energy contained in the shock wave transferred, through the fluid, to the target deposit. More particularly, in accordance with the present invention, a flexible guide member is provided for insertion through a fluid- containing body passage or surgically created passage. The guide member is positioned with its distal end adjacent the target deposit. The flexible guide member has a hollow adjacent its distal end. In use, the hollow is filled with a working fluid, which is continuously replenished from an external source. Energy pulse waves are generated in the working fluid in the hollow adjacent the distal end of the guide member by means of an electrical discharge (spark) , and the resultant shock wave expressed from the hollow through an opening in the distal end of the guide member and impinged directly on the deposit whereby to fracture or erode the deposit. In one embodiment of the invention, the flexible guide member distal end comprises a metallic body nozzle, and the electrical discharge (spark) is generated across the working fluid between a single electrode extending into the working fluid and the metallic body. In another embodiment of the invention, a pair of spaced electrodes extend into the hollow adjacent the distal end of the guide member, and the electrical discharge (spark) may be generated across the working fluid between the two spaced electrodes. In yet another embodiment of the invention, the electrohydraulic lithotripsy device also includes an optic viewing system carried by the guide member and terminating adjacent the distal end of the guide member. In a preferred embodiment of the invention, a nozzle, preferably in the shape of a parabolic or semi-spherical reflector, with rectangular electrodes disposed axially of the reflector on opposite sides thereof is provided on the distal end of the guide member for focusing the resulting shock wave. The invention will be more fully understood from the following solely exemplary detailed description taken in conjunction with the accompanying drawings, in which like numerals depict like parts, and wherein: Fig. 1 is a block diagram of an electrohydraulic lithotripsy device made in accordance with the invention; Fig. 1A is a view, similar to Fig. 1, showing an alternative form of electrohydraulic lithotripsy device made in accordance with the present invention; Fig. 2 is an enlarged view, in cross-section, and showing details of one embodiment of electrohydraulic lithotripter device made in accordance with the present invention; Fig. 3 is similar to Fig. 2, and illustrating details of another embodiment of electrohydraulic lithotripter made in accordance with the present invention; Fig. 4 is a view similar to Fig. 2, and illustrating details of yet another embodiment of electrohydraulic lithotripter made in accordance with the present invention; Fig. 5 is a cross-sectional view taken along plane 5-5 of Fig. 1A; Fig. 6 is an end view of a preferred embodiment invasive lithotripter tip constructed in accordance with the present invention; Fig. 7 is a side view of the lithotripter of Fig. 6; Fig. 8 is a side view taken at right angles to Fig. 7, and with a portion broken away to illustrate the electrode construction relative to the parabolic or semi-spherical reflector; Fig. 9 is a cross-sectional view of the body of the electrode showing the basic electrode construction; Fig. 10 is a side view partly in axial section of the lithotripter tip having a safety shield positioned around the enclosing tip and spark area; and Fig. 11 is a side view partly in axial section showing the relation of the lithotripter tip to a kidney stone or other concretion. The present invention contemplates an apparatus for fracturing or eroding hard deposits in fluid-containing body passages by means of hydraulic force. Referring to Fig. 1, in accordance with the present invention, there is provided a guide member 50 having a hollow opening 52 at its distal end 54, and containing a working fluid 56 from a source 58. The guide member 50 comprises an elongate hollow tube, and is positioned with its distal end 54 adjacent, but spaced from, a target deposit 60 which may be a kidney stone arterial plaque or the like, and an electrical discharge spark is generated as will be described in detail hereinafter, in the working fluid adjacent the guide member distal end 54. Working fluid 56 comprises a biologically acceptable fluid such as 1/6 normal USP saline solution, which is flowed into guide member 50 by means of a pump 62. Guide member 50 may comprise a hollow tube as illustrated in Fig. 1, preferably comprising a metallic, hollow stub tube 64 mounted on the tube distal end 54. Alternatively, as shown in Fig. 2, an apertured metal nozzle 70, preferably of ellipsoid shape and typically formed of brass or stainless steel, may be mounted on the distal end 54 of tubing 50 in fluid communication with the working fluid source through one or more apertures 74 formed in the back wall of nozzle 70. An electrode 76 is insulatively mounted, extending into nozzle 70 in communication with the working fluid contained therein. Electrode 76 is connected via conductor wire 80 to one terminal of a spark generator 84. A second conductor wire 82 connects the body of nozzle 70 to the other terminal of spark generator 84. Spark generator 84, which may be any one of several commercially available spark generators such as a Wolfe 2137.50 or Northgate Research SDI, has its output applied on conductor wires 80 and 82. Spark generator 84 produces an output pulse of up to several microseconds, at several Kv and up to 1 Ka current. The spark generated between the tip of the electrode 76 and the metal nozzle body causes a vapor expansion of the working fluid contained within the nozzle adjacent the electrode tips which in turn causes a shock wave in the working fluid contained in the nozzle. Nozzle 70 shapes the resultant shock wave to a focal zone or focal point 86 permitting the resultant shock wave to fracture calciferous deposits upon which it impinges. Referring now to Fig. 1A, the electrohydraulic lithotripsy device of the present invention also may include an optic viewing system carried by the guide member 50 and terminating adjacent the distal end of the guide member. Referring also to Fig. 5, the viewing system comprises an optical viewing conduit 120 terminating adjacent the distal end of the guide member 50, compiling optics (not shown) of conventional construction for permitting viewing from the external proximal end of the guide member 50, and illuminating means such as a laser light transmitting fibers 122, also terminating adjacent the distal end of the guide member 50, for emitting light from a light source (not shown) external to the guide member 50. The viewing conduit 120 can be a flexible fiberoptic bundle, a thin lens system, a rod lens system, or a graded index (GRIN) system. The operation of viewing conduits, coupling optics and light sources are well known in the art and need not be described in further detail. Referring to Fig. 3, there is shown yet another embodiment of the invention. In the Fig. 3 embodiment, the nozzle 94 may have an internal inverse conical hollow 96 narrowing to the end 98 of the nozzle. Alternatively, as shown in Fig. 4, the nozzle 102 may have an internal conical hollow 104 opening to the end 106 of the nozzle. One or more apertures 108 are formed in the back wall 100 of nozzle 102 for permitting replenishment of working fluid from the fluid source. In use, the guide member or nozzle tip distal end is positioned in close spaced relation to the target deposit. Pump 22 is activated, whereby to force a continuous stream of working fluid into the nozzle hollow. The pulse generator is activated, providing a spark within the working fluid contained in the guide member or nozzle hollow. This spark, in turn, causes a rapid vapor expansion which, in turn, causes a pulse-like shock wave in the working fluid which is expressed from the hollow in pulsed shock waves to impinge directly on the target deposit to be removed. The pulsed shock waves impinging on the target nozzle fractures and erodes the target deposit. A feature and advantage of the present invention is that only the working fluid and shock wave contacts the target deposit. Thus, the problems of impact tip fragmentation and metal fines formation experienced with metal tip impact lithotripsy devices of the prior art is eliminated. Also, since the spark is generated in a confined tube, the surrounding tissue is protected from the damaging effects of the plasma. Various changes may be made in the above invention without departing from the spirit and scope thereof. For example, the tube distal end or nozzle may be formed of a hard, heat-resistant, reinforced material such as a ceramic, or a suitable plastic such as Teflon or other materials having sufficient heat resistance and burst strength to withstand the heat and shock wave generated by the spark. In such case the nozzle or tube distal end should be fitted with a pair of spaced electrodes, each connected via a conductor wire to one terminal of the spark generator 44, whereby a spark may be generated between the spaced electrodes. The electrodes also may comprise a coaxial wire electrode system or a parallel wire electrode system as are well known in the art. A particularly preferred embodiment of the present invention is illustrated in Figs. 6-11 which illustrate an electrohydraulic lithotripsy device comprising, in combination, a parabolic or semi-spherical reflector, with rectangular electrodes disposed axially of the reflector on opposite sides thereof. A spark is discharged between the electrodes substantially across the apex of the reflector. A protective shell surrounds the reflector and the electrode. The parabolic or semi-spherical reflector focuses the Shockwave to be concentrated on the stone or stones to be disintegrated. The rectangular electrodes cooperate with the reflector in providing the spark, and hence the Shockwave at the proper location. Furthermore, the rectangular electrodes present the best cross sectional area utilization for the lowest resistance per length as compared with a coaxial cable type electrode to provide the best efficiency of transferring electrical energy to the spark tip. The delivered energy is on the order of 4-8 kilovolts DC with currents ranging from 100 to 500 amperes for short durations of about 1 microsecond. As will be seen, slight decreases in resistance can substantially reduce the electrode energy losses, while delivering high energy electro-hydraulic Shockwaves. Also, rectangular electrodes permit the best spacing possible at the tip. It has been known that the hydraulic energy delivered is a strong function of the length of the spark gap. Rectangular electrodes with an insulator in a 2 French electrode (2 millimeter circumference) configuration permit a spark gap distance which is equal to or greater than a 3 French coaxial electrode (3 millimeter circumference). The reason for this is that the rectangular electrode tip presents only one insulator surface to the spark, whereas the coaxial electrode tip presents two insulator surfaces (one on each side of the central electrode), and thus the rectangular electrode can more efficiently utilize the cross-sectional area available to provide the longest spark gap possible for a given electrode size. Referring in particular to Figs. 6-10, there is shown an invasive lithotripter 10 constructed in accordance with the principles of the present invention. The lithotripter includes an insulating reflector 12, which is rectangular in end view (Fig. 6), having side surfaces 14 and end surfaces 16. The insulating reflector is also rectangular in the front view of Fig. 8, with the important exception of a left facing parabolic or semi-spherical reflector surface 18. This surface is seen also in Fig. 6, where it opens toward the viewer. Metallic, conductive electrodes 20 are disposed on opposite sides 14 of the insulating reflector 18, and are insulated from one another thereby. The outer end of each electrode 20 as indicated at 22 in Fig. 8 extends outwardly from the apex 24 of the parabolic or semi- spherical reflector 18, so that the outer portions of the electrodes are spaced from one another, and insulated from one another by the reflector 12. The ends may be struck with a punch or the like at 26 to form small protrusions 28 extending into the space above the apex of the reflector. These protrusions are located aligned with the focus of the parabolic or semi-spherical reflector. A pair of conductive wires 30 are respectively integral with or connected by any suitable means to the electrodes 20, and lead to electrical circuitry (not shown) for producing a high voltage spark between the electrodes, across the reflective surface 18. The wires 30 are individually insulated by polyamide sheaths 32, and an encapsulating polyamide sheath 34 surrounds the reflector and the electrode to hold the assembly together. Although the initial parts of the invention have now been described, certain details thereof will be of interest. It is to be noted that the parabolic or semi- spherical reflector 18 is not a paraboloid or hemisphere of revolution, but rather is a parabolic or cylindrical section. The electrodes can be separate metallic pieces suitable secured to the conductive wires 30, or they preferably can be portions of these wires. Stainless steel may be used. Copper also presents a lower electrical resistance. The electrode tip's important parameters include the electrode spacing, or the distance between the electrodes where the spark may jump, the protective outer wrap which provides containment and direction for the spark energy, and reflector insulator, which also provides direction for the spark energy. The primary objective is to provide the strongest spark energy in the axial direction with the weakest radial spark energy. This combination provides the safest electrode operation without fear of perforating the ureter or other tissue with the continued capability to fragment the calculi (stone). The insulation, as noted, is preferably polyamide, which is of superior electrical characteristics, having a dielectric strength of 4,000 volts per mil. The shape of the outer insulating sheath 34 as seen in Fig. 6 is an irregular octagon. This shape allows cavities between it the usually round lumen through which it is passed, for irrigant to flow. The rectangular electrode wires 20 provide a low capacitance per unit length, lower than an equivalent round coaxial electrode. Lower capacitance provides for faster rise times and more efficient spark generation with higher peak energies for stone disintegration. Although it is possible for a spark to travel from one electrode surface to another electrode surface throughout the area in which the electrodes are not insulated from one another by the reflector, the projections 28 tend to localize the spark at the focus point of the reflector. Accordingly, the Shockwave generated by the spark (which flashes some of the surrounding urine and any added aqueous solution into steam) is focused by the reflector so that the Shockwave travels substantially linearly from the left end (as viewed in the drawings) of the lithotripter for most efficient impingement against the concretion, such as kidney stone to be disintegrated. The total overall dimensions are quite small. Referring first to Fig. 6, the maximum distance from left to right is 0.0212 inch, which the maximum height is 0.022 inch. The distance across diagonally opposite corners is 0.0254 inch. The electrodes 20 are 0.014 x 0.004 inch as viewed in Fig. 6. The vertical height of the reflector as viewed in Fig. 6 is 0.020 inch, while the width is 0.0112 inch. The projection of the reflector beyond the ends of the electrodes as seen in Fig. 7 is 0.005 inch, while each of the polyamide insulators 32 is 0.003 inch thick, the outer wrap 34 being .0005 inch thick. The shape of the reflective surface has been set forth heretofore, and it is noted that this technically is a parabolic or semi-spherical cylinder. A further important aspect of the present invention is shown in Figs. 10 and 11. The parts heretofore described remain without change and are identified by the same numerals previously used. The distinction resides in the provision of a cylindrical shield 38 surrounding the electrodes 20 and the reflector 12. The shield 38 is made of suitable plastic material and resiliently grips the sheath 34 and extends axially beyond the reflector to a termination 40. The shield helps to locate the lithotripter 10 relative to a kidney stone 42 or the like, and helps to focus the Shockwave energy on the stone. A scope 44 is shown surrounding the lithotripter in Fig. 11 and water circulation is indicated by arrows 46. Perhaps more importantly, the shield both reflects and absorbs energy, inhibiting radial distribution of energy which might perforate surrounding tissue. Such tissue perforation would turn a simple procedure into an extensive procedure. The present invasive lithotripter constitutes a 2 French electrode which is superior to the existing 3 French electrode that is the industry standard. For a given transverse dimension the rectangular wires have a larger area than round wires, and thus has a lower resistance per unit length. They also have lower capicitance per unit length. The lower resistances and capacitance produce a hotter spark, and thus produce a Shockwave having more energy. The energy delivered is a strong function of the spark gap. The correct 3 French coaxial electrode has a spark gap of 0.006 inch, but in the electrode area this is expanded to 0.011 inch by the insulating reflector. This increases the effective energy by a factor of about 2. This addition of the reflective surface increases the amount of energy delivered to the stone by a further factor. In the preferred example, the electrodes 20 are simply extensions of the conducting wires 30, and the wires theretofore are of the same dimensions as the electrodes. The total length of the outer sheath 34 in Fig. 8 is 132 cm, while the total length to the right of the outer sheath is 5 cm, permitting connection to the external electronic circuitry. The protective safety shield in Fig. 10, projects approximately 2-3mm beyond the electrode spark face dimples item 26 as in Fig. 6. The length of this extension is related to the energy applied to the electrode and the size and shape of the spark generated. The capacitance per unit length is less for a rectangular electrode than for a coaxial electrode. With lower capacitance per unit length, a faster rise time spark may be generated, which causes a faster rise time hydraulic Shockwave with greater stone destruction power. The trend in medical practice is to use smaller instruments. Smaller instruments may be more easily inserted within patients with less potential harm. Recently, small optical scopes have been developed with internal channels of smaller diameter, typically of approximately 2.1 French construction 82 millimeter circumference). However, the stones remain the same size and require the same destructive power. Accordingly, it becomes a necessity for constructing lithotripsy electrodes with small cross sections but retaining similar or greater power delivery capability than larger previously available electrodes. Commercially available electrodes of choice generally have been 3 French (120 millimeter in circumference) with some sizes ranging up to 9 French. The invention may take other forms, and/or be employed for other uses. For example, the device may be dimensioned so as to provide a low energy spark which may be useful for resolving spasms in vessels, or to dilate narrowing of hollow internal structures. It will therefore be understood that all matter herein described or shown in the accompanying drawings is to be interpreted as illustrative only, and is not to limit the invention defined in the following claims.

Claims: 1. Apparatus adapted for fracturing hard targets, reducing spasm in target vessels or dilating narrowing in hollow targets within a body characterized by comprising, in combination: a flexible elongate guide member (50) adapted for insertion within the body with the distal end thereof positioned adjacent a target, said guide member having an apertured hollow (52) adjacent its distal end (54); means (62) for supplying a working fluid (56) to said hollow from an external source (58); a hollow tube (64) formed of a heat and shock resistant material mounted on the distal end of said guide member; and means (76) for discharging an electric spark within said hollow tube from an external energy source (84) for generating pulsed shock waves in the working fluid for impinging on said target. 2. Apparatus according to claim 1, wherein said hollow tube comprises a nozzle (70) for shaping the fluid. 3. Apparatus according to claim 2, wherein said nozzle (70) has an internal ellipsoid shape. 4. Apparatus according to claim 5, wherein said nozzle (106) has an internal conical shape. 5. Apparatus according to claim 1, wherein said external energy source comprises a spark generator (44). 6. Apparatus according to claim 1, wherein said tube (64) is formed of metal. 7. Apparatus according to claim 1, wherein said tube (64) is formed of ceramic. 8. Apparatus according to claim 1, wherein said tube (64) is formed of a heat-resistant plastic. 9. Apparatus according to claim 1, and further including an optic viewing system (120) carried by said guide member and terminating adjacent the distal end of said guide member for permitting viewing from external the proximal end of said guide member. 10. Apparatus according to claim 9, wherein said optic viewing system (120) comprises a fiberoptic bundle. 11. Apparatus according to claim 9, wherein said optic viewing system (120) comprises thin lens system, a rod lens system, or a graded index system. 12. Apparatus according to claim 9 and including an illuminating means (122) terminating adjacent the distal end of said guide member for emitting light from a light source external to the guide member. 13. A lithotripter comprising a pair of electrodes (20) respectively having substantially flat faces confronting one another, an insulating member (18) interposed between and spacing said electrodes a pre- determined distance apart, said insulating member having an edge opening relieved area exposing portions of said electrode flat faces toward one another to permit an electric spark to jump between the exposed electrode faces, a pair of conductors (30) respectively connected to and leading from said electrodes for conducting a spark inducing potential to said electrodes from an electrical source, a spark between said electrodes in an aqueous environment generating a Shockwave to fracture a bodily concretion, and insulating material (34) securing said electrodes and said insulating spacing member together. 14. A lithotripter as set forth in claim 13, and further including aligned protrusions (28) on the exposed portions of said flat faces for localizing a spark discharge. 15. A lithotripter as set forth in claim 13, wherein the relieved area of said insulating member provides a reflector surface (18) for focusing the Shockwave. 16. A lithotripter as set forth in claim 14, wherein the relieved area of said insulating member provides a reflector surface (18) for focusing the Shockwave. 17. A lithotripter as set forth in claim 16, wherein the reflecting surface on the insulating member has a focus point, and wherein said protrusions (28) are aligned with said focus point. 18. A lithotripter as set forth in claim 13, wherein the confronting faces (14) of the electrodes are rectangular, and wherein the cross sections of said electrodes are rectangular. 19. A lithotripter as set forth in claim 18, wherein said conductors (30) respectively comprise extensions of said electrodes with substantially the same cross section. 20. A lithotripter as set forth in claim 13, wherein said insulating member (12) comprises a ceramic member. 21. A lithotripter as set forth in claim 13, wherein said electrodes have outer ends (22) aligned with one another, said electrodes further having longitudinal edges and a predetermined width between longitudinal edges, said insulating member (34) being wider than said predetermined width and extending on both sides beyond said longitudinal edges, said insulating member (34) extending beyond outer ends of said electrodes and being relieved behind said outer ends. 22. A lithotripter as set forth in claim 13, and further including a shield (38) surrounding and extending beyond said electrodes (20) and said insulating member (34) and preventing radial Shockwaves and permitting axial Shockwaves. 23. A lithotripter comprising a pair of electrode members (20) each of rectangular cross section and respectively having substantially flat surfaces confronting one another, insulating material (32) respectively encircling each of said electrode members, additional insulating material (34) encircling said electrode members and said first mentioned insulating material, said electrode members being spaced apart a predetermined distance by said first mentioned insulating material, each of said electrode members adjacent an end thereof having an electrically exposed area (22) whereby a spark may pass between said exposed areas in an aqueous environment to generate a Shockwave for fracturing a bodily concretion. 24. A lithotripter as set forth in claim 23, and further including an insulating member (18) interposed between said electrode members adjacent the electrically exposed areas and spacing said electrode members adjacent said insulating member by a distance greater than said predetermined distance, said insulating member (18) being shaped to focus the Shockwave in a predetermined direction. 25. A lithotripter as set forth in claim 24, and further including a substantially cylindrical shield (38) encircling and extending beyond said electrode members, said insulating materials and said insulating member to inhibit radial propagation of Shockwave while enhancing axial propagation thereof. 26. A lithotripter as set forth in claim 24, said insulating member (18) having a focus point (24), said electrode member exposed areas having confronting protuberances substantially aligned with said focus point for localizing spark discharge adjacent said focus point. 27. A lithotripter comprising a pair of electrodes (20) and having axial and radial directions, insulating means (12) spacing said electrodes apart and exposing confronting electrical conductive areas of said electrodes for permitting a spark between said confronting areas on an aqueous medium to generate a Shockwave, and a shield (38) encircling said insulating radial propagation Shockwave energy while enhancing axial propagation thereof. 28. A lithotripter as set forth in claim 27, wherein said insulating means (12) includes a reflective surface (18) shaped to focus Shockwave energy in an axial direction. AMENDED CLAIMS [received by the International Bureau on 13 July 1992 (13.07.92) ; original claims 6-8 cancelled ; original claim 1 amended ; claims 8-28 unchanged but renumbered as claims 6-25 other claims unchanged (4 pages)] 1. Apparatus adapted for fracturing hard targets, reducing spasm in target vessels or dilating narrowing in hollow targets within a body characterized by comprising, in combination: a flexible elongate guide member (50) adapted for insertion within the body with the distal end thereof positioned adjacent a target, said guide member having an apertured hollow (52) adjacent its distal end (54); means (62) for supplying a working fluid (56) to said hollow from an external source (58); a metallic hollow tube (64) formed of a heat and shock resistant material mounted on the distal end of said guide member; and means (76) for discharging an electric spark within said hollow tube from an external energy source (84) for generating pulsed shock waves in the working fluid for impinging on said target. 2. Apparatus according to claim 1, wherein said hollow tube comprises a nozzle (70) for shaping the fluid. 3. Apparatus according to claim 2, wherein said nozzle (70) has an internal ellipsoid shape. 4. Apparatus according to claim 5, wherein said nozzle (106) has an internal conical shape. 5. Apparatus according to claim 1, wherein said external energy source comprises a spark generator (44). 6. Apparatus according to claim 1, and further including an optic viewing system (120) carried by said guide member and terminating adjacent the distal end of said guide member for permitting viewing from external the proximal end of said guide member. 7. Apparatus according to claim 6, wherein said optic viewing system (120) comprises a fiberoptic bundle. 8. Apparatus according to claim 6, wherein said optic viewing system (120) comprises thin lens system, a rod lens system, or a graded index system. 9. Apparatus according to claim 6 and including an illuminating means (122) terminating adjacent the distal end of said guide member for emitting light from a light source external to the guide member. 10. A lithotripter comprising a pair of electrodes (20) respectively having substantially flat faces confronting one another, an insulating member (18) interposed between and spacing said electrodes a pre- determined distance apart, said insulating member having an edge opening relieved area exposing portions of said electrode flat faces toward one another to permit an electric spark to jump between the exposed electrode faces, a pair of conductors (30) respectively connected to and leading from said electrodes for conducting a spark inducing potential to said electrodes from an electrical source, a spark between said electrodes in an aqueous environment generating a Shockwave to fracture a bodily concretion, and insulating material (34) securing said electrodes and said insulating spacing member together. 11. A lithotripter as set forth in claim 10, and further including aligned protrusions (28) on the exposed portions of said flat faces for localizing a spark discharge. 12. A lithotripter as set forth in claim 10, wherein the relieved area of said insulating member provides a reflector surface (18) for focusing the Shockwave. 13. A lithotripter as set forth in claim 11, wherein the relieved area of said insulating member provides a reflector surface (18) for focusing the Shockwave. 14. A lithotripter as set forth in claim 13, wherein the reflecting surface on the insulating member has a focus point, and wherein said protrusions (28) are aligned with said focus point. 15. A lithotripter as set forth in claim 10, wherein the confronting faces (14) of the electrodes are rectangular, and wherein the cross sections of said electrodes are rectangular. 16. A lithotripter as set forth in claim 15, wherein said conductors (30) respectively comprise extensions of said electrodes with substantially the same cross section. 17. A lithotripter as set forth in claim 10, wherein said insulating member (12) comprises a ceramic member. 18. A lithotripter as set forth in claim 10, wherein said electrodes have outer ends (22) aligned with one another, said electrodes further having longitudinal edges and a predetermined width between longitudinal edges, said insulating member (34) being wider than said predetermined width and extending on both sides beyond said longitudinal edges, said insulating member (34) extending beyond outer ends of said electrodes and being relieved behind said outer ends. 19. A lithotripter as set forth in claim 10, and further including a shield (38) surrounding and extending beyond said electrodes (20) and said insulating member (34) and preventing radial Shockwaves and permitting axial Shockwaves. 20. A lithotripter comprising a pair of electrode members (20) each of rectangular cross section and respectively having substantially flat surfaces confronting one another, insulating material (32) respectively encircling each of said electrode members, additional insulating material (34) encircling said electrode members and said first mentioned insulating material, said electrode members being spaced apart a predetermined distance by said first mentioned insulating material, each of said electrode members adjacent an end thereof having an electrically exposed area (22) whereby a spark may pass between said exposed areas in an aqueous environment to generate a Shockwave for fracturing a bodily concretion. 21. A lithotripter as set forth in claim 20, and further including an insulating member (18) interposed between said electrode members adjacent the electrically exposed areas and spacing said electrode members adjacent said insulating member by a distance greater than said predetermined distance, said insulating member (18) being shaped to focus the Shockwave in a predetermined direction. 22. A lithotripter as set forth in claim 21, and further including a substantially cylindrical shield (38) encircling and extending beyond said electrode members, said insulating materials and said insulating member to inhibit radial propagation of Shockwave while enhancing axial propagation thereof. 23. A lithotripter as set forth in claim 21, said insulating member (18) having a focus point (24), said electrode member exposed areas having confronting protuberances substantially aligned with said focus point for localizing spark discharge adjacent said focus point. 24. A lithotripter comprising a pair of electrodes (20) and having axial and radial directions, insulating means (12) spacing said electrodes apart and exposing confronting electrical conductive areas of said electrodes for permitting a spark between said confronting areas on an aqueous medium to generate a Shockwave, and a shield (38) encircling said insulating radial propagation Shockwave energy while enhancing axial propagation thereof. 25. A lithotripter as set forth in claim 24, wherein said insulating means (12) includes a reflective surface (18) shaped to focus Shockwave energy in an axial direction. STATEMENT UNDER ARTICLE19 Nowhere within the four corners of Tessler is there disclosure, or for that matter suggestion, of apparatus for fracturing hard targets, etc., within a body, and comprising a flexible elongate guide member having a metallic, hollow tube on the distal end thereof, and means for applying a working fluid to the hollow from an external source, as required by new claim 1. Nowacki teaches an extracorporeal shock wave lithotripsy (ESWL) device. Suffice it to note, Nowacki does not include a flexible elongate guide member for insertion into the body as required by Applicants' claims. Under the circumstances, none of Applicants' claims can be said to be anticipated by Nowacki. It is not seen that Filler supplies the missing teachings to Tessler and Nowacki to achieve or render obvious Applicants claims. Filler teaches an extracorporeal shock wave lithotripsy (ESWL) device comprising a conical sector shock tube. Howeve beyond the common touchstone of teaching that a shock wave ca be shaped or focussed, Filler adds nothing to the missing teachings of Tessler and/or Nowacki to achieve or render obvious Applicants' claimed invention. Moreover, it is believed that Filler, an extracorporeal lithotripsy device constitutes non-analogous art. Suffice it to note that extracorporeal lithotripsy devices are highly complex million dollar machines, while Applicants' electrohydraulic lithotrips device is a relatively simple and inexpensive device. The remaining references cited to show the state of the art, but not applied, are not believed to impact on the patentability of the instant invention. A particular feature and advantage of Applicants' claimed invention is that Applicants' electrohydraulic lithotripsy device offers a low cost alternative to extracorporeal lithotripsy devices which, as noted above, are highly complex million dollar machines, and also offers a cost savings alternative to laser lithotripsy devices which typically cost in the neighborhood of about a quarter of a million dollars. Moreover, Applicants' claimed device is safe to use, and the metallic hollow tube mounted on the distal end of the guide member shields adjacent surrounding tissue from both the spark and from impact by the shock wave. Yet another feature and advantage of the present invention and which results from the combination of a metallic hollow tube mounted on the distal end of the guide member, and supplying working fluid to the hollow from an external source is substantially increased lifetime achieved by Applicants' claimed invention. As compared to conventional electrohydraulic lithotripsy devices which are subject to severe erosion problems and thus typically may have a lifetime of perhaps 150 pulses, Applicants' device, due to the combination of a metallic sleeve and irrigation has been shown to have a lifetime in excess of 2,000 pulses. Comparative test data to this effect is available, and the Examiner is respectfully requested to telephone the undersigned attorney before issuing a further action so that appropriate comparative test data may be presented.

Inventors: BHATTA KRISHNA M, MANTELL ROBERT R, SCHILDGEN ROBERT M, SYPAL KENNETH L, BHATTA, KRISHNA, M., MANTELL, ROBERT, R., SCHILDGEN, ROBERT, M., SYPAL, KENNETH, L.
Applicants: BHATTA KRISHNA M, NORTHGATE TECHNOLOGIES INC, BHATTA, KRISHNA, M., NORTHGATE TECHNOLOGIES INCORPORATED
Application year: 1992
Main classification: A61B17
IPC codes: A61B17, A61B18, A61N1