Surgery – Instruments – Electrical application
Reexamination Certificate
1998-05-08
2002-04-30
Dvorak, Linda C. M. (Department: 3739)
Surgery
Instruments
Electrical application
C606S046000, C606S048000, C606S050000, C607S101000
Reexamination Certificate
active
06379349
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates to an arrangement for the electrothermal treatment of the human or animal body, in particular for the electrocoagulation or electrotomy.
The use of high-frequency alternating currents in the frequency range of 300 kHz to 2 MHZ for tissue coagulation and tissue separation has long been known in the field of surgery, resulting in the treated tissue being coagulated or vaporized, which is referred to as electrocoagulation or electrotomy. A distinction must be made here between the monopolar and the bipolar HF thermotherapy.
For the monopolar thermotherapy, an electrode—also referred to as the neutral electrode—is configured as a large-surface patient lead and is installed near the place of incision on the patient. The shape of the actual working electrode—referred to as the active electrode—is adapted to the respective application. Thus, large-surface sphere, disk or needle electrodes are used for the tissue coagulation, whereas thin lancet or loop-type electrodes are used for tissue separation.
In the bipolar HF thermotherapy, on the other hand, both electrodes are arranged in close proximity to the place of incision, so that the effect of the alternating current is limited to the area immediately surrounding the place of incision, thereby resulting in a high degree of safety for the patient and the user since accidents caused by capacitive leakage currents or burning at the neutral electrode can no longer occur. Another advantage of the bipolar HF thermotherapy consists in the considerably lower load resistance of the tissue between the two electrodes, which permits a reduction in the necessary generator output while maintaining the thermal effect.
Based on the position of the electrodes, the HF thermotherapy can furthermore be divided into the surface coagulation on the one hand and the depth coagulation on the other hand.
The bipolar technique uses two parallel-arranged tactile electrodes for the surface coagulation, which are placed onto the tissue surface. As a result of this, the tissue underneath is heated, owing to the flow of current, and is thus coagulated.
The use of needle, lancet, or loop-type electrodes for the monopolar electrotomy is known in the field of depth coagulation. Electric arcs must be generated for this on the active electrode in order to vaporize the tissue, positioned in front of the active electrode, thereby realizing a tissue cut. This is relatively simple with the monopolar technique because only a specific field strength is required to trigger a spark discharge at the active electrode. The bipolar technique makes higher demands on the design of the electrode configuration since the physical processes in this case cannot be controlled as easily. That is why only a few bipolar electrode arrangements for the depth coagulation are known, e.g. the bipolar needle electrode, which is suitable, among other things, for the myoma therapy. This known bipolar electrode arrangement consists of two parallel-arranged needle electrodes that are stuck into the tissue, by means of which the tissue between the electrodes is heated as a result of the current flow and is thus coagulated.
However, the known bipolar electrode arrangements for the depth coagulation have the disadvantage that placement of the electrodes through two puncture sites is relatively involved. Furthermore, the predetermination of the field distribution by the user is relatively imprecise because the position of the two electrodes relative to each other generally cannot be specified exactly.
The DE 43 22 955 A1 furthermore discloses the use of laser radiation for the coagulation of body tissue, which laser radiation can be transmitted into the therapy region via a cylindrical optical waveguide, wherein the known optical waveguide additionally permits the transmission of ultrasound energy, so that the two therapy methods of ultrasound tissue separation and the laser coagulation can be combined.
A waveguide is also disclosed in the DE 44 32 666 A1, which makes it possible to transmit high-frequency energy in addition to ultrasound waves and laser radiation, so that the initially mentioned methods of high frequency surgery can be used at the same time as the laser surgery and the ultrasound surgery. For this, the known waveguide has a cylindrical design and additionally comprises two layers of an electrically conductive material for the high-frequency transmission, which layers are also cylindrical and are electrically insulated against each other. Thus, the known waveguide permits the transmission of high-frequency energy from a high-frequency generator, arranged extracorporeal, into the therapy region, but it does not permit the release of the high-frequency energy to the body tissue.
SUMMARY OF THE INVENTION
It is thus the object of the invention to create an arrangement for the electrothermal treatment of the human or animal body, which permits an interstitial tissue coagulation by means of a bipolar electrode arrangement and which avoids the aforementioned disadvantages of the known types of arrangements.
The invention includes the technical teaching that a bipolar electrode arrangement is used for the thermotherapy, the two electrodes of which are arranged one after another on an elongated catheter to make it possible to insert the two electrodes jointly into the body through a single puncture site, wherein the two electrodes are connected to the catheter or form a component of the catheter.
Herewith and in the following, the term catheter is understood to have a general meaning. It is not limited to the preferably used hollow-cylindrical arrangements, described in detail in the following, but can also be realized with large arrangements of nearly optional cross sections. Critical to the function according to the invention is only that the two electrodes are inserted jointly into the patient's body, through one puncture site.
The catheter according to the invention for the first time allows placing the electrodes into deep tissue layers and obtaining a partial tissue coagulation there.
The electrodes in the arrangement according to the invention are connected to a current source that supplies the electrical energy necessary for heating up the tissue. The term current source here is not limited to narrowly defined sources having a constant current, but includes also the preferably used alternating current generators, especially high-frequency generators.
One advantageous variant of the invention provides that the axial distance between the two electrodes can be adjusted, so that the field distribution can be varied. If the insulator length in axial direction between the two electrodes is shorter, for example, than twice the electrode diameter, spherical coagulation necroses can be obtained advantageously, whereas the shape of the coagulation necroses for longer insulator lengths is more oval.
The preferred embodiment of this variant therefore provides that the proximal electrode has a hollow design, at least at its distal end, such that it can accommodate the distal electrode on its inside. The external cross section of the distal electrode is smaller than the internal cross section of the proximal electrode to allow an axial displacement of the distal electrode inside the proximal electrode. It is important in this case for the two electrodes to be electrically insulated against each other in a suitable manner, since the two electrodes can overlap in axial direction. An electrical insulation is provided for this on the inside of the proximal electrode or on the outside of the distal electrode. For example, this insulation can consist of a dielectric coating or an insulating material sleeve, preferably composed of PTFE or polyimide—as in the initially listed reference DE 44 32 666 A1—wherein the cross section for the insulating-material sleeve is preferably adapted to the cross section of the distal or proximal electrode, such that the insulating-material sleeve can be press-fitted to the proximal or distal electrode and is thus fixed on
Desinger Kai
Möller Gerhard
Celon AG medical instruments
Dvorak Linda C. M.
Kinberg Robert
Ruddy David M.
Venable
LandOfFree
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