Electrosurgical instrument and method of use

Abstract

A particular embodiment of the invention provides an electrosurgical working end for performing high strength welding of tissue comprising a body having a tissue contacting energy delivery surface. The body includes pixel portions and non-pixel portions distributed within the tissue contacting surface. The pixel portions comprise a positive temperature coefficient of resistance (PTCR) material with at least one pixel portion configured to switch Rf current on and off in the at least one pixel portion responsive to tissue temperature adjacent the at least one pixel portion. The pixel portions can be configured to be coupled to an Rf current source such as an Rf generator. The pixelated energy delivery surfaces are capable of highly localized modulation of Rf energy application to the engaged tissue to create high strength tissue welds.

Description

CROSS-REFERENCES TO RELATED APPLICATIONS[0001]This applications claims the benefit of priority of U.S. Provisional Application No. 60 / 552,978 (Attorney Docket No. 021447-002100US), filed on Mar. 12, 2004, the full disclosure of which is incorporated herein by reference. This application is also related to co-pending U.S. patent application Ser. No. 10 / 032,867 filed Oct. 22, 2001 (Attorney Docket No. 021447-000500US) titled Electrosurgical Jaws Structure for Controlled Energy Delivery, U.S. patent application Ser. No. 10 / 351,449 filed Jan. 22, 2003 (Docket No. 021447-000100US) titled Electrosurgical Instrument and Method of Use, U.S. patent application Ser. No. 10 / 443,974, filed May 22, 2003 (Docket No. 021447-000590US) titled Electrosurgical Working End with Replaceable Cartridges, and Provisional U.S. Patent Application Ser. No. 60 / 523,567, filed Nov. 19, 2003 (Docket No. 021447-000560US) titled Electrosurgical Instrument and Method of Use, all of which are fully incorporated herei...

AI Technical Summary

Benefits of technology

[0011]In another aspect, embodiments of the invention provide system and methods for uniformly heating and welding tissue using the application of Rf energy. In order to create the most effective “weld” in tissue, a targeted volume of tissue is desirably uniformly elevated to the temperature needed to denature proteins therein. To create a “weld” in tissue, collagen, elastin and other protein molecules within an engaged tissue volume are desirably denatured by breaking the inter- and intra-molecular hydrogen bonds—followed by re-crosslinking on thermal relaxation to create a fused-together tissue mass. It can be easily understood that ohmic heating in tissue—if not uniform—can at best create localized spots of truly “welded” tissue. Such a non-uniformly denatured tissue volume still is “coagulated” and will prevent blood flow in small vasculature that contains little pressure. However, such non-uniformly denatured tissue will not create a seal with significant strength (e.g. burst or leak strength, etc), for example in 2 mm. to 10 mm. arteries that contain high pressures. Accordingly, embodiments of the invention utilize positive temperature coefficient of resistance and related materials to sense and respond to temperature in engaged tissue to modulate Rf energy delivery to the engaged tissue to uniformly heat a target tissue volume to in turn produce a uniformly denatured tissue volume and thus, a uniformly welded tissue volume

[0015]In many embodiments, the PTRC body can comprises a matrix comprising PTRCR pixels disposed in a field material (i.e., a non pixilated material) such as an electrically insulative polymer material. The jaw structure can be configured to use the PTCR pixels for one or more of the following: i) performing highly localized, pixelated temperature sensing of ohmically heated tissue; ii) controlling current flow in engaged tissue on a highly localized pixelated basis; iii) producing rapid on-off switching of current flow to engaged tissue on a highly localized pixelated basis; and iii) producing highly localized, pixelated Rf current densities in engaged tissue. In various embodiments, the pixel portions can comprise an array wherein each pixel is independently switchable, responsive to the temperature of tissue adjacent each pixel portion, or another tissue property such as resistance, hydration level etc. Also, the array can be the array configured to produce a substantially uniform thermal effect in tissue including at least one of tissue welding, tissue weld strength, ohmic heating or protein denaturization.

[0017]In an exemplary method of using the above embodiment of the working end and related embodiments, tissue is engaged with the tissue contacting surface of the working end and Rf energy is then delivered to tissue to ohmically heat tissue. Rf current flow to tissue through at least one pixel portion can then be switched or toggled off or one responsive to the temperature of ohmically heated tissue adjacent the at least one pixel portion. This switching can be done on a micron scale so that current flows in one pixel, but is switched off in an adjacent pixel only microns away. On a more macro scale, the switching of current flow can also be utilized to produce a substantially uniform thermal effect in a tissue volume engaged with the tissue contacting surface. This thermal effect can include without limitation, uniform tissue welding, tissue weld strength, ohmic heating, uniform protein denaturization, uniform. Additionally, the switching of current flow can be utilized to create regionalized or pixilated current densities in the engaged tissue which can correlate to the pixel portions.

Problems solved by technology

However, such non-uniformly denatured tissue will not create a seal with significant strength (e.g. burst or leak strength, etc), for example in 2 mm. to 10 mm. arteries that contain high pressures.

Such surface coagulation does not create a weld that provides any substantial strength in the affected tissue.

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