Surgery – Instruments – Electrical application
Reexamination Certificate
2001-07-30
2004-04-20
Peffley, Michael (Department: 3739)
Surgery
Instruments
Electrical application
C606S041000
Reexamination Certificate
active
06723094
ABSTRACT:
The invention concerns an electrode arrangement for a surgical instrument for electrothermal coagulation of tissue, which includes a front cylinder at the distal end of the instrument having a distal tip, a carrier proximally adjoining the front cylinder, and two electrodes which are connectable to an ac voltage source.
Using the application of high-frequency alternating currents (for example in the frequency range of between 300 KHz and 2 MHz) to generate high temperatures for tissue coagulation and for tissue division has long been known in surgery. In a practical context, so-called monopolar electrode arrangements or bipolar electrode arrangements are used for introducing the HF-current into the tissue.
In the case of the monopolar arrangements, an electrode—also referred to as the neutral electrode—is applied in the form of an electrode of large area to the skin of the patient in the proximity of the treatment location and fixed there and earthed or connected to ground. A second electrode which is manipulated by the operator—also referred to as the active electrode—is connected to the ac voltage source. In terms of its shape, the electrode is so adapted to the respective use, in particular the size of the tissue area to be treated, that both the operational time and also the thermal loading of the region of the body or organ involved are reasonable and they coagulate only the desired area of tissue.
In the case of arrangements for bipolar HF-thermotherapy, both electrodes are connected to an HF-generator and arranged with dimensions which are fixed with respect to each other, for example on an insulating carrier, and are placed by the operator in the immediate proximity of the treatment location and generally also actively guided.
WO 97/17009 discloses a bipolar electrode arrangement with a fluid duct by way of which flushing fluid can be introduced into the operational area. Two or three electrodes are arranged in the form of a cone portion on a conical distal tip of the instrument which can be introduced into the tissue, wherein the electromagnetic HF-field is formed between the electrodes and is intended to coagulate the surrounding tissue.
WO 96/34569 and the documents referred to in the associated international search report disclose systems and processes for the coagulation of body tissue while maintaining a pre-calculated maximum tissue temperature, in which fluid cooling or thermoelectric cooling is provided during the actual tissue coagulation procedure. Those known arrangements are intended for the introduction into body cavities by way of natural accesses.
U.S. Pat. No 4,832,048 as well as WO 95/10320 and WO 99/11186 or EP 96 945 879.3 and WO 98/19613, WO 96/18349 and WO 81/03272 also disclose surgical instruments which treat tissue by means of HF-thermotherapy by means of a bipolar electrode arrangement.
The known surgical instruments for bipolar HF-thermotherapy are often expensive to manufacture and, for the various areas of use involved, they often suffer from disadvantages which frequently result in locally inaccurate tissue treatment which in particular in part does not reach the tissue to be treated or thermally overloads sound tissue.
Therefore the object of the present invention is to develop an electrode arrangement for a surgical instrument of the kind set forth in the opening part of this specification, such that it is simple to manufacture and use and permits precise localizable treatment of the tissue, while at the same time sparing surrounding sound tissue.
That object is attained by an electrode arrangement for a surgical instrument for thermoelectric coagulation of tissue, including an electrically conductive front cylinder at the distal end of the instrument, with a distal tip and with a cylindrical first electrode, a tubular outer conductor proximally adjoining the front cylinder and with a cylindrical second electrode, an insulator element between the front cylinder and the outer conductor, wherein the electrodes are connectable to an ac voltage source, characterised by a bar-shaped inner conductor in the outer conductor and an insulating tube between the inner conductor and the outer conductor.
The advantages of the invention are in particular that the electrode arrangement is of a particularly simple structure, wherein more specifically the front cylinder forms an electrode and that the proximally adjoining outer conductor which is insulated by way of an insulator element forms the second electrode so that the ac voltage source is connectable to the front cylinder and from the outside directly to the outer conductor by way of the bar-shaped inner conductor which is separated by an insulating tube outer conductor.
The insulating element has between the front cylinder and the outer conductor a radial partition which at the outside goes into a cylindrical casing wall which surrounds the front cylinder and/or the outer conductor in closely fitting relationship therewith over a predetermined axial lengthwise portion. The inner conductor is connectable to the front cylinder through that partition of the insulating element. Preferably, embodied between the front cylinder and the inner conductor is a releasable screw connection in which the inner conductor carries at its distal end a male screwthread which can be screwed to a corresponding axial female screwthread in the front cylinder. The advantages of this embodiment are in particular that the cup-like insulator element can be applied in the form of an insulating layer directly to the metal front cylinder and/or the metal outer conductor, in such a way that the separating surface between the front cylinder and the outer conductor and a lengthwise portion, axially adjoining same, of the outside surface has a coating with an insulating material. A coating of that kind can be produced for example in accordance with the invention by anodization of the surfaces in question in an electrolyte bath if the front cylinder and/or the outer conductor comprise an anodizable metal, for example titanium or aluminum.
Depending on the respective purpose of use the electrode arrangement for an instrument can be of a flexible nature so that in that case the inner conductor, the outer conductor, the insulating tube and possibly also the insulator element comprise an elastic material. In the case of a flexible surgical instrument of that kind, the bipolar electrode arrangement can under some circumstances be more easily moved to the specific treatment location. Alternatively however the inner conductor and the outer conductor can be of a straight and rigid configuration, in which case then the front cylinder and the outer conductor are arranged in mutually coaxially aligned arrangement and can then be moved to the treatment location by a rectilinear translatory movement. In regard to certain treatment locations it may also be particularly advantageous to angle the instrument in the lengthwise direction.
In all embodiments the outer conductor and the front cylinder are of substantially the same outside diameter in order to provide for unimpeded sliding movement of the electrode arrangement in the tissue.
Preferably the front cylinder, over its axial lengthwise portion which is not covered by the insulator element, forms the first electrode and the outer conductor, over the entire axial lengthwise portion, insofar as same is not covered by the insulator element, forms the second cylindrical electrode. The axial length of the electrodes is preferably greater than the axial length of the insulator element and it is also greater than the outside diameter of the front cylinder and the outer conductor. Preferably the length of the outer conductor is a multiple of the length of the front cylinder. If, in this embodiment, the tissue adjoining the outside surface of the instrument is coagulated and as a result becomes of high resistance, then in this embodiment of the invention the electromagnetic field can be displaced outwardly into adjoining tissue regions because there is a suitably long second electrode so that, if the
Beck & Tysver PLLC
Peffley Michael
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