Surgery – Instruments – Electrical application
Reexamination Certificate
1998-05-29
2001-05-15
Cohen, Lee (Department: 3739)
Surgery
Instruments
Electrical application
C606S041000, C606S048000, C606S159000, C606S194000, C607S099000
Reexamination Certificate
active
06231572
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates generally to surgical devices and more specifically to electrosurgical catheters adapted to incise body material defining a body conduit.
2. Discussion of the Prior Art
Various surgical devices have been used to electrosurgically ablate or otherwise cut body materials. In this type of surgery, electrosurgical energy is passed between two electrodes creating a high current density which ablates the body materials. In a typical monopolar system, the patient is coupled to a large grounding pad which forms one of the electrodes. The electrosurgical device forms the other electrode. In this system, the electrosurgical device provides a very low surface area and consequently a very high current density for ablation or cutting in proximity to the device. In a bipolar system, the two electrodes are included in the device and high current density is achieved in the small area between the electrodes.
These electrosurgical devices include a catheter having a balloon and an electrode extending over the surface of the balloon as disclosed in applicant's co-pending applications, Ser. No. 08/241,007, filed on May 11, 1994, and entitled “Angioplasty Catheter and Method for Making Same”, and Ser. No. 08/216,512, filed on Mar. 22, 1994, and entitled “Improved Catheter with Electrosurgical Cutter”. The entirety of this disclosure is incorporated herein by reference. This catheter is used in a monopolar system where an electrode, in the form of a wire, is disposed over a radially expandable balloon of the catheter. As the balloon is inflated, the electrode is carried radially outwardly into proximity with the body material to be ablated or cut. Although it has always been of interest to increase the current density associated with the wire electrode, this has been difficult to achieve as smaller wire sizes necessarily result in reduced electrode strength and integrity. The balloon material has also been restricted to insure against over-expansion and electrode proximity. Materials forming non-distensible balloons have been preferred, but have made it difficult to achieve a low-profile state for insertion.
SUMMARY OF THE INVENTION
In accordance with the present invention, an electrosurgical catheter is provided with a balloon and an electrode extending axially along the outer surface of the balloon. A sleeve is disposed over the balloon and provided with ends which float along the catheter body between a low-profile state and a high-profile state for the sleeve. In the high-profile state, the sleeve has a predetermined maximum diameter which limits the radial dimension of the balloon. Portions of the electrode extend through the sleeve to facilitate the electrosurgical function. The sleeve can also be provided with characteristics whereby the sleeve is biased to its low-profile state further facilitating a minimal profile for the catheter. The sleeve will typically be manufactured of a thermoplastic or thermoset material.
The sleeve can be formed from a plurality of elements which are woven, braided, or otherwise stranded to form an expandable structure. The electrode may form one of these elements in the sleeve. The electrode may also be formed from elements which are stranded to increase the surface area of the electrode without increasing its diameter. The electrode, the balloon, or the sleeve can be coated with an insulation to control the electrical relationships between these elements.
For example, the electrode can be formed of stranded elements which provide the electrode with an outer surface having peaks and valleys. Portions of this insulation can be removed to expose the elements in a straight or curved pattern. The electrode can be connected at each of its ends through conductors to the proximal end of the catheter thereby facilitating increased current flow to the electrode.
In another embodiment, the guidewire can be provided with an electrically conductive core which is exposed through insulation to energize the electrode at the distal end of the catheter. Using the guidewire as a conductor eliminates the need for an additional conductor in the catheter to energize the electrode. The conductive guidewire also facilitates operative disposition of the catheter at the surgical site.
In a semi-bipolar system, either the balloon or the sleeve can be used as a second electrode replacing the grounding pad in a typical monopolar system. With the wire forming one of the electrodes, the metalized balloon or sleeve forms the other electrode in a semi-bipolar system. This system provides the advantage of current density at the wire, but does not require electrical current to be conducted throughout the body of the patient. The electrosurgical current need only flow from the active electrode with a minimal surface area to the balloon or sleeve which provide a high-surface area.
In one aspect of the invention, a catheter is adapted to increase the patency of a body conduit and comprises an elongate tube having an axis extending between a proximal end and a distal end. A balloon is disposed at the distal end of the tube and provided with properties for being expanded to a high-profile state and for being contracted to a low-profile state. A sleeve is disposed over the balloon and provided with a pair of ends which define a central section of the sleeve. The ends of the sleeve are disposed to floatingly engage the tube with the central section disposed circumferentially of the balloon. An electrode includes portions disposed outwardly of the sleeve and having properties for being electrosurgically energized to incise the body materials and increase the patency of the body conduit.
In another aspect of the invention, the electrode is formed of a plurality of elements stranded between a proximal end and a distal end to provide the electrode with an elongate configuration.
In a further aspect of the invention, the electrode has a radial cross-section which is non-circular in configuration.
In a further aspect of the invention, a guide member is adapted to facilitate insertion of a catheter into a body conduit. The guide member includes a core extending along an axis between a proximal end and a distal end, the core having properties for conducting energy. Insulation is disposed over the core with a portion of the insulation defining an exposed portion of the core at the proximal end of the guidewire and at the distal end of the guidewire.
In a further aspect of the invention, a combination includes the guide member and a catheter with an elongate shaft adapted to be moved along the guide member. An electrode disposed along the catheter is coupled to an exposed conductive core of the guide member to permit passage of energy from the proximal end of the guidewire along the core to the electrode at the distal end of the catheter.
REFERENCES:
patent: 5024617 (1991-06-01), Karpiel
patent: 5196024 (1993-03-01), Barath
patent: 5891136 (1999-04-01), McGee et al.
patent: 5904679 (1999-05-01), Clayman
patent: 2209676 (1989-05-01), None
patent: 91/17717 (1991-01-01), None
Ewers Richard C.
Hart Charles C.
Hilal Nabil
Pravongviengkham Bounsavanh
Applied Medical Resources Corporation
Cohen Lee
Myers, Esq. Richard L.
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