Surgery: light – thermal – and electrical application – Light – thermal – and electrical application – Electrical energy applicator
Reexamination Certificate
2000-12-14
2003-03-04
Paschall, Mark (Department: 3742)
Surgery: light, thermal, and electrical application
Light, thermal, and electrical application
Electrical energy applicator
C607S098000, C607S126000, C607S116000, C606S041000
Reexamination Certificate
active
06529778
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to electrode leads. More particularly it relates to an electrode lead for the delivery of electrical signals to a muscle tissue with metallic electrode and an electrolytic fluid serving as a fluid-phase interface between the electrode and muscle tissue.
BACKGROUND OF THE INVENTION
Conventional metallic electrodes had been described in the art as means for delivering electrical pulses for the control of skeletal or cardiac muscles, See for example PCT/IL97/00012 (published as WO 97/25098), titled ELECTRICAL MUSCLE CONTROL (Ben-Haim et al.) incorporated herein by reference, which disclosed a method and apparatus for locally controlling the electrical and/or mechanical activity of cardiac muscle cells, in situ.
Cardiac pacing, defibrillation, as well as other electrical muscle control (hereafter referred to as—excitable tissue control, ETC) devices use electrodes to deliver electrical pulses that may vary in duration from 0.1 to 2 Ms (milliseconds) in the case of pacing up to 10 to 40 ms in the case of ETC.
In some other ETC applications, for example electronic cardioplegia, as described in US patent application Ser. No 09/320,091 (Ben-Haim et al.), filed Jun. 26, 1999 titled INDUCTION OF CARDIOPLEGIA USING APPLIED ELECTRICAL SIGNALS, electrical pulses may have a duration similar to that of the cardiac cycle (about 1s)
Operated under certain muscle-control protocols—especially those requiring relatively strong or long electrical pulses—an electrode may inflict local tissue damage caused by electrolytic and thermal mechanisms due to direct electrode-tissue interface (contact). This limits the range of waveforms and amplitudes that can be applied using metallic-phase electrodes or non-flowing ionic-phase electrodes (such as Ag—AgCl electrodes with gelled AgCl interface).
In the present invention the metallic electrode is not placed in direct physical contact with the muscle tissue. Instead coupling is achieved through the use of a flowing electrolytic fluid which promptly dissipates heat, prevents the formation of high-current density areas, and considerably reduces the contamination of the muscle tissue by electrolytes and sparing the tissue from direct electrolyte damage.
Although to the best knowledge of the applicants fluid-phase electrodes have never been described as the delivery means for stimulating or muscle-control signals, electrodes with flowing electrolytic medium had been described as means for delivering radio-frequency (RF) energy for the purpose of creating lesions in the cardiac tissue. See for example U.S. Pat. No. 5,676,693 (LaFontaine), titled ELECTROPHYSIOLOGY DEVICE, incorporated herein by reference.
The use of flowing electrolyte had also been described as a means for reducing the conductivity of tissue in vicinity to an ablation electrode in U.S. Pat. No. 5,431,649 (Muller et al.), titled METHOD AND APARATUS FOR RF ABLATION, incorporated herein by reference.
In general however, the delivery of fluids to the vicinity of an electrode had not been used to form a fluid-phase electrical interface between a metallic-phase electrode and the target muscle tissue. Rather, fluid delivery to the vicinity of an electrode had been used to reduce localized tissue heating during ablation (see, for example, U.S. Pat. No 5,334,193 (Nardella), titled FLUID COOLED ABLATION CATHETER, U.S. Pat. No. 5,437,662 (Nardella), titled FLUID COOLED ELECTROSURGICAL CAUTHERIZATION SYSTEM, U.S. Pat. No. 5,520,684 (Imran), titled TRANSURETHRAL RADIO FREQUENCY APPARATUS FOR ABLATION OF THE PROSTATE GLAND AND METHOD). It had also been described as the mechanism for ablation (e.g. cryogenic ablation see U.S. Pat. 4,943,290 (Rexroth) titled ELECTROLYTE PURGING ELECTRODE TIP), as well as to pharmacological enhancement of the therapeutic effect of ablation (e.g. delivery of sclerotic agents as described in U.S. Pat. No. 5,403,311 (Abele et al.) titled ELECTRO-COAGULATION AND ABLATION AND OTHER ELECTROTHERAPEUTIC TREATMENTS OF BODY TISSUE), or delivery of chemotherapeutic agent to an ablated tumor site as described in U.S. Pat. No. 5,507,743 (Edwards) titled COILED RF ELECTRODE TREATMENT APPARATUS), all incorporated herein by reference.
It is an object of the present invention to provide an electrode for cardiac electrical tissue control whereby the metallic part of the electrode is not placed in direct physical contact with the cardiac tissue.
It is further an object of the present invention to provide such an electrode that uses electrolytic fluid as the coupling agent in order to prevent the creation of high-current density areas (hot spots), dissipate heat generated by Tissue Control signal on the target tissue, and considerably reduce the contamination of the target tissue by electrolytes and thus prevent direct electrolyte damage to the tissue.
Yet another object of the present invention is to provide such an electrode that allows the employment of a broader range of muscle-control waveforms and amplitudes than those which can be safely applied to the target tissue when using metallic-phase or non-flowing ionic-phase electrodes.
BRIEF DESCRIPTION OF THE INVENTION
It is thus perovided, in accordance with a preferred embodiment of the present invention, a fluid-phase electrode lead apparatus for the delivery of electrical signals to an excitable tissue comprising:
a catheter, having distal and proximal ends;
at least one electrode provided at the distal end of said catheter, electrically connectable to an electric signal generator;
means for providing electrolytic fluid to facilitate electric conduction of an electric signal from said at least one electrode to said excitable tissue.
Furthermore, in accordance with a preferred embodiment of the present invention, said at least one electrode is kept at a distance from said excitable tissue.
Furthermore, in accordance with a preferred embodiment of the present invention, said distance is in the range of 1 to 3 millimeters.
Furthermore, in accordance with a preferred embodiment of the present invention, said catheter is provided with an internal conduit through which said electrolytic fluid is provided.
Furthermore, in accordance with a preferred embodiment of the present invention, said apparatus is further provided with an internal conduit fluidically connected to means for providing vacuum to facilitate anchoring of said distal end of the catheter to said excitable tissue.
Furthermore, in accordance with a preferred embodiment of the present invention, said apparatus is further provided with an internal conduit fluidically connected to means for providing vacuum to facilitate anchoring of said distal end of the catheter to said excitable tissue.
Furthermore, in accordance with a preferred embodiment of the present invention, said internal conduit fluidically connected to means for providing vacuum further protrudes relatively to said internal conduit through which said electrolytic fluid is provided, both conduits provided with widening rims, and wherein said electrode is positioned near the rim of said internal conduit through which said electrolytic fluid is provided.
Furthermore, in accordance with a preferred embodiment of the present invention, said conduits are coaxial.
Furthermore, in accordance with a preferred embodiment of the present invention, said rims are flexible.
Furthermore, in accordance with a preferred embodiment of the present invention, the apparatus is further provided with a cap fluidically connected to said internal conduit through which said electrolytic fluid is provided.
Furthermore, in accordance with a preferred embodiment of the present invention, said electrode is provided on the inside of said cap.
Furthermore, in accordance with a preferred embodiment of the present invention, said cap is further provided with hooks serving as anchoring means for anchoring the cap to said excitable tissue.
Furthermore, in accordance with a preferred embodiment of the present invention, the apparatus is further provided with a cap, said cap provided with anchoring means for a
Impulse Dynamics N.V.
Paschall Mark
Reed Smith LLP
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