Surgery – Instruments – Electrical application
Reexamination Certificate
1997-09-30
2002-12-17
Kearney, Rosiland S. (Department: 3739)
Surgery
Instruments
Electrical application
C606S041000, C606S048000, C606S049000, C606S050000
Reexamination Certificate
active
06494881
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to electro-surgical devices, and more particularly to improved electro-surgical devices having selectively insulated portions for use in resection and cauterization procedures.
BACKGROUND
There are many medical procedures in which tissue is cut or carved away for diagnostic or therapeutic reasons. For example, a transurethral resectioning of the prostate (TURP) is performed to treat benign or cancerous prostatic hyperplasia. Transurethral resectioning may also be performed in the bladder (TURB). The obstructing tissue can be resected, ablated, or coagulated with any number of electro-cautery devices which are inserted into the urethra through a resectroscope. An electric current heats the tissue sufficiently to break inter-cellular bonds, cutting the tissue, or denaturing the tissue in order to remove or perform coagulation on tissue.
Extensive bleeding can occur as a result of electro-resectioning, which can obstruct the physician's view and lead to dangerous blood loss levels. Additionally, during these procedures a pressure differential exists between the urinary tract and the circulatory system. This pressure differential may result in an uptake of ambient fluid during the procedure, possibly causing complications. The bleeding can be treated or avoided by coagulating the tissue in the treatment area with an electro-coagulator that applies a low level current to denature cells to a sufficient depth without breaking intercellular bonds.
Existing electro-cautery devices tend to be inefficient when used with an electrolytic fluid such as saline, because energy applied to a resecting electrode rapidly diffuses into the fluid and chips that have already been removed, due to the conductive nature of the fluid and tissue. As a result, resection is either inadequately carried out, or a greater amount of energy is applied to the electrode to perform resectioning, raising a concern that adjacent healthy tissues may be damaged during the resectionig procedure.
It is therefore an object of the invention to provide an electrosurgical probe that can adequately perform electro-cautery while focusing the energy on the desired location.
SUMMARY OF THE INVENTION
The present invention features an electrosurgical device that is made more efficient and safer than conventional electrosurgical probes by selectively coating portions of the electrode in the device with an insulative or dielectric coating. The present invention provides an appropriate insulative coating that is capable of remaining adhered to an electrode during a resectioning procedure, in which the electrode is subjected to extremely high temperatures and voltages. Various polymer materials including Teflon, and ceramic materials have been tried as insulative coatings, however, such materials have been known to crack under a high temperature environment and therefore are unsuitable as coating materials for resecting electrodes.
In one aspect, the invention features an electro-surgical device, having an elongated body, a pair of arms extending from a distal end of the elongated body, and a loop electrode connecting the pair of arms. The elongated body is adapted to be coupled to a source of energy at a proximal end. The loop electrode defines a pair of end sections and a base section, and is formed of a conductive material. Each end section is coupled to an aim and comprises the conductive material having an insulative coating disposed thereon. The base section disposed between the end sections comprises the conductive material free of the insulative coating, thereby focusing energy emission to the tissue undergoing resection and cauterization.
In one embodiment, the insulative coating on the end sections can be a diamond-like coating or other coating having sufficient properties permitting it to withstand high voltages and temperatures. In another embodiment, the diamond-like coating can be vapor deposited onto the end sections. The insulative coating can have a thickness up to about 10 microns.
In another embodiment, the electro-surgical device comprises an elongated body, a pair of arms extending from a distal end of the elongated body, and an electrode in communication with the pair of arms. The elongated body is adapted to be coupled to a source of energy at a proximal end. The electrode has a first region covered with an insulative coating and a second region covered with a sacrificial material. The sacrificial material covering the second region disintegrates during the application of normal energy levels, exposing a conductive region underneath.
In another embodiment, the insulative coating can be vapor deposited on the first region, and the sacrificial material can be deposited on the second region by dipping, spraying, or brushing. The insulative coating is capable of remaining adhered to the first region upon application of a voltage of up to from about 1000 volts to about 2000 volts (rms) at mains frequency. The insulative coating can be a diamond-like coating.
In still another embodiment, the electro-surgical device comprises an elongated body, a pair of arms extending from a distal end of the elongated body, and an electrode in communication with the pair of arms. The elongated body is adapted to be coupled to a source of energy at a proximal end. The electrode has a non-uniformly deposited insulative coating capable of remaining adhered to the electrode upon application of a voltage of up to about 200 volts (rms), wherein the areas where the coating is thinner can degrade exposing the portion of the electrode which comprises the second region, focusing energy emission.
In another embodiment, the insulative coating can have a hardness of greater than 1000 kg/mm
2
, a dielectric strength of greater than about 100 volts (rms) per &mgr;m and an electrical resistivity in the range from 10
2
ohm-cm to 10
2
ohm-cm. In yet another embodiment, the electrode can be a cylindrical roller electrode, or a spherical roller electrode.
In another aspect, the invention features a resectoscope assembly. The assembly includes a resectoscope having a channel and an electro-surgical device insertable through the channel. The electro-surgical device includes an elongated body, a pair of arms in communication with the elongated body and a distal electrode in communication with the pair of arms. The electrode has a first region coated with an insulative coating and a second region for focusing energy emission. The insulative coating is capable of remaining adhered to the electrode upon application of a voltage of up to 500 volts (rms) at mains frequency.
In still another aspect, the invention features a method for performing selective cauterization. An electro-surgical device is positioned along a treatment path near tissue to be resected. The electro-surgical device includes an elongated body, a pair of arms in communication with the elongated body and a distal electrode in communication with the pair of arms. The electrode has a first region coated with an insulative coating and a second region for focusing energy emission. The insulative coating is capable of remaining adhered to the electrode upon application of a voltage of up to 500 volts (rms) at mains frequency. The tissue is flushed with a non-osmotic fluid. A plasma field is generated near the second region of the electrode and the tissue. The electro-surgical device is moved along the treatment path to resect and coagulate the tissue.
In each of the above embodiments, the electro-surgical device can be efficiently used with a non-osmotic fluid, such as, for example, saline, glycine or sorbitol. Moreover, the electro-surgical device of the present invention can be used in saline, an electrolytic, non-osmotic fluid without a considerable loss of energy to the tissue undergoing treatment or the fluid. Additionally, the present invention avoids the use of high currents to deliver energy to the treatment site, as energy is effectively focused in the conductive section or sections of the electrode. The result is higher current densi
Abele John E.
Bales Thomas O.
Calhoun Michael W.
Sixto, Jr. Robert
Kearney Rosiland S.
Scimed Life Systems Inc.
Testa Hurwitz & Thibeault LLP
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