| Thermal cautery devices with improved heating profiles -> Monitor Keywords |
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Thermal cautery devices with improved heating profilesRelated Patent Categories: Surgery, Instruments, Heat Application, Tip Or Other Heat Concentration Means, Tip In Electrical CircuitThermal cautery devices with improved heating profiles description/claimsThe Patent Description & Claims data below is from USPTO Patent Application 20060212031, Thermal cautery devices with improved heating profiles. Brief Patent Description - Full Patent Description - Patent Application Claims
[0001] This application is a continuation of U.S. application Ser. No. 10/713,490 filed Nov. 14, 2003, now U.S. Pat. No. 7,011,656. FIELD OF THE INVENTIONS [0002] The inventions described below relate to instruments and methods for sealing, joining, and cutting tissue. BACKGROUND OF THE INVENTIONS [0003] The devices described below provide for improved heat transfer and sealing performance for our Starion.RTM. line of thermal cautery forceps and thermal ligating shears, and in instruments such as those disclosed in Treat, et al., Electrothermal Instrument For Sealing And Joining Or Cutting Tissue, U.S. Pat. No. 6,626,901 (Sep. 30, 2003) (the disclosure of which is hereby incorporated in its entirety). SUMMARY [0004] The thermal cautery and thermal ligating devices disclosed in U.S. Pat. No. 6,626,901 are improved by the addition of a thermally conductive plate proximate to the resistive heating element used in those devices. BRIEF DESCRIPTION OF THE DRAWINGS [0005] FIGS. 1 and 2 illustrate laparoscopic thermal ligating shears designed to provide thermal ligation and division in numerous endoscopic procedures. [0006] FIG. 3 illustrates a forceps embodiment of a thermal cautery device. [0007] FIG. 4 illustrates the prior art construction of the distal tip of a thermal cautery device. [0008] FIGS. 5 and 6 are cross sections of thermal cautery or thermal ligating devices with a thermally conductive plate interposed between the resistive heating element and the grasping face of the distal tip of the grasping arm of the device. [0009] FIG. 7 illustrates the effect of the thermal cautery or thermal ligating devices on a segment of body tissue. [0010] FIGS. 8 and 9 illustrate embodiments of the heating element and thermally conductive plate. [0011] FIG. 10 illustrates a method of testing the thermal cautery or thermal ligating devices. DETAILED DESCRIPTION OF THE INVENTIONS [0012] FIGS. 1 and 2 illustrate laparoscopic thermal ligating shears of the type marketed by Starion Instruments, Inc. with the improved heating assembly described below. These shears are designed to provide thermal ligation and division in numerous endoscopic procedures. The shears 1 comprises distal end 2 with remotely operable grasping assembly 3 and a proximal end 4 with a pistol grip actuator 5. The distal end is adapted for insertion into the body of a patient through a laparoscopic access port. The grasping assembly comprises small grasping arms 6 and 7, operably connected to the pistol grip actuator through the pivot section (hinge 8) and actuator rod 9 running through the rigid tube 10, such that operation of the actuator causes the grasping arms to open and close, thereby moving the respective grasping faces into apposition to each other. A resistive heating element (a heater wire or tube) 11 is fixed to the grasping face of the first grasping arm, running over the grasping face from the distal end to the proximal end of the grasping face. The first grasping arm is also covered with a resilient, non-stick, thermally insulative sleeve 12 to provide a resilient pad 13 on the grasping face under the heater wire, between the heater wire and the grasping face. A resilient, thermally insulative sleeve 14 covers the second grasping arm to provide a resilient pad on the grasping face of the second arm. A small thermally conductive but electrically insulative plate or sheet 15 is disposed over the first grasping face, extending laterally across the grasping face and longitudinally under the heating element. [0013] FIG. 2 provides a close up view of the grasping assembly 3, showing the heater wire 11 thermally insulative sleeve 12 on the first grasping arm. Suitable materials for the sleeves and/or resilient pads include polytetrafluoroethylene (PTFE), KAPTON, mica, or silicone. Each sleeve serves to even out pressure applied to tissue and insulates the surfaces of grasping arms electrically and thermally. The thermally conductive but electrically insulative plate is visible between the heating element 11 and the resilient pad 12. As shown in the figure, the plate may be curved and contoured to match the curvature of the grasping face, which in this case is arcuate in the distal-to-proximal aspect, and rounded laterally across the grasping face. This plate serves as a heat spreader to broaden the zone of heat application as illustrated below. The plate may be constructed of a high thermal conductivity metal such as aluminum, copper (and metals of lesser thermal conductivity such as titanium) and the like, a high thermal conductivity ceramics such as boron nitride or aluminum nitride or the like, or a plastic material incorporating a high thermal conductivity metal or ceramic. If the heat spreader is constructed of a material that is an electrical conductor, the heat spreader must be electrically isolated from the resistive heating element. Thus, if comprised of metal, the plate and resistive heating element must be electrically insulated with a high temperature electrical insulator. This may be accomplished with an electrically insulative layer formed of an oxidized surface on the metal plate, such as can be done with metals such as titanium or aluminum. These materials may be covered by a thick layer of oxide of the metal, or by anodizing the metal plate, or with an electrically non-conductive coating on the metal plate or under the resistive wire. [0014] FIG. 3 illustrates thermal cautery forceps of the type marketed by Starion Instruments, Inc. with the addition of the improved heating assembly. The forceps 21 comprises grasping arms in the form of elongate forceps arms 22 and 23 with proximal ends 24 and 25 resiliently mounted to a pivot section (handle section 26). The outer surfaces of forceps arms 22 and 23 are fitted with finger grips 27 and 28 to assist the operator in holding and activating the forceps. The opposing surfaces of the distal tips 29 and 30 of the forceps establish grasping faces which are aligned on each grasping arm so as to meet the grasping face of the other grasping arm upon closure of the grasping arms. Closure of the grasping arms is accomplished manually. The forceps arms may be formed of a suitable resilient material such as stainless steel, plastic, composites, etc. that have the desired combination of stiffness and resilience. [0015] The distal tips include the various elements of the heating assembly. A resistive heating element (a heater wire) 34 is disposed on the grasping face of distal tip 30, secured to the distal end of the grasping arm 23 and extending proximally over the grasping face of the grasping arm toward the proximal end of the grasping arm. The distal tip 30 is also covered with a resilient, non-stick, thermally insulative sleeve 35 to provide a resilient pad 36 on the grasping face under the heater wire, between the heater wire and the grasping face. The grasping face of the opposing distal tip 29 may also be covered by a resilient, non-stick, thermally insulative surface 37, provided as a portion of sleeve 38 disposed over the distal tip 29, in order to provide an anvil surface upon which the heating element acts during operation. The thermally conductive but electrically insulative plate 39 is disposed between the heating element 34 and the resilient pad 36. [0016] Additional elements of the forceps are also shown in FIG. 3. The a finger-operated switch 40 preferably comprises a multi-directional post-in-tube design with a control button 41 and a contact switch disposed in opposition to one of the grasping arms which is operably connected with the power supply (not shown) and the heating element such power cannot be supplied to the heating element unless the contact switch is engaged when a user squeezes the grasping arms. [0017] FIG. 4 is a cross section illustrating a prior art construction of the distal tip of a thermal cautery device, while FIG. 5 is a cross section of a thermal cautery device with a thermally conductive plate interposed between the resistive heating element and the grasping face of the distal tip of the grasping arm of the device. The components of the heating assembly components shown in FIG. 3 appear in both figures, with the exception of the plate 39. As discussed in reference to FIG. 3, the grasping face of the distal tip 30 is covered with the resilient pad 36 (which, as illustrated, is a portion of resilient sleeve 35 (the resilient sleeve may also establish a fluid-filled (air or liquid) gap over the outer surface of the distal tip, which helps prevent thermal damage to body tissue in the vicinity of the tissue to be cauterized and ligated)), and the resistive heating element 34 is disposed over the grasping face, over the resilient pad, so that it is located between the grasping faces. The distal tip 29 is covered by the resilient sleeve 38 to establish the resilient pad 37 on the grasping face of this distal tip. [0018] In addition to the structure shown in FIG. 4, FIG. 5 shows the placement of the plate 39, interposed between the heating element and the grasping face of the forceps arm 23. The plate is arcuate, such that it bulges away from the grasping face of forceps arm 23 along its long distal-to-proximal centerline and bows away from the opposing grasping face toward the lateral sides of the device. A typical length of body tissue 42 is shown, held between the grasping faces. In FIG. 4, the extent of heat affected zone in the body tissue is indicated by arrow 43. The high heat generated by the heating wire, combined with light pressure exerted on the body tissue, results in division at line 44. In comparison, as shown in FIG. 5, the extent of heat affected zone in the body tissue, when the plate 39 is used, is indicated by arrow 45. The wide lateral extent of heat affected zone results in a more secure seal of the tissue. [0019] In FIG. 6, which shows the grasping face of the distal tip 30 of the active grasping arm 23, covered by the resilient pad 36, the resistive heating element 34 disposed over the grasping face and the distal tip 29 of the opposing grasping arm with its resilient sleeve 38, along with the plate 39 interposed between the heating element and the grasping face of the active grasping arm 23. In this figure, the distal tip 30 of the active grasping arm 23 is cylindrical, with a substantially circular radial cross section. The resilient sleeve 35 surrounds and closely conforms to the cylindrical grasping arm, and the thermally conductive plate 39 is semi-cylindrical, and is disposed over the sleeve, between the sleeve and the resistive heating element. This embodiment provides for improved contact between the heat spreader and thicker tissues. The resultant divided tissue is shown in FIG. 7, which shows the small area of division on either side of line 44, and the wide lateral extent of thermally sealed tissue boundaries 46 and 47. Continue reading about Thermal cautery devices with improved heating profiles... Full patent description for Thermal cautery devices with improved heating profiles Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this Thermal cautery devices with improved heating profiles patent application. ###  How KEYWORD MONITOR works... a FREE service from FreshPatents1. Sign up (takes 30 seconds). 2. Fill in the keywords to be monitored. 3. Each week you receive an email with patent applications related to your keywords. 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