Patent Application
20060217791
The present invention is related to catheters having electrical leads.
In order for a catheter to deliver and/or receive electrical signals from a patient's body, it is necessary to provide a structure for carrying an electrical impulse between the proximal end of the catheter to the distal end. This is conventionally accomplished by either providing one or more electrical wires in a lumen of the catheter or by embedding a wire in the wall of the catheter. For example, U.S. Pat. No. 5,584,873 (“the '873 Patent”) discloses a medical electrical lead including an elongated lead body provided with multiple conductor lumens each containing a conductor and at least one compression lumen which does not contain a conductor.
Conventional catheters which include electrical leads are susceptible to problems such as kinking. During kinking, the lumens lying within a kinking plane may collapse, thereby preventing flow of fluid through the lumens. Prior art catheters have attempted to diminish the effect of kinking by arranging the lumens such that not all the lumens lay in the same kinking plane. Thus, at least one of the lumens would remain open during kinking. This may assist in preserving a catheter's ability to deliver fluid, but during kinking a further problem may develop in that the electrical leads within the catheter may become damaged, thereby deteriorating or in some cases eliminating the catheters ability to deliver and/or receive electrical impulses. Further, forming catheters with internal electrical leads requires a somewhat complicated and expensive manufacturing process.
Accordingly, there is a need for a catheter having electrical leads that are not susceptible to damage when the catheter is kinked and/or bent and that can be manufactured easily and inexpensively.
One aspect of the invention provides a catheter that is able to deliver and/or receive electrical impulses reliably even when subjected to kinking and/or bending.
Another aspect of the invention provides a catheter that is relatively kink resistant.
Another aspect of the invention provides a catheter having electrical conductors which are less likely to be damaged when the catheter is bent and/or kinked.
A catheter according to an exemplary embodiment of the invention includes a lead body, at least one lumen extending longitudinally through the lead body, and at least one conductor formed on an outside surface of the lead body and extending from a proximal end portion of the lead body to a distal end portion of the lead body.
A method of forming a catheter according to an exemplary embodiment of the invention includes forming a lead body comprising at least one lumen extending longitudinally through the lead body, and disposing at least one conductor on an outside surface of the lead body, the at least one conductor extending from a proximal end portion of the catheter to a distal end portion of the catheter.
In at least one embodiment, the at least one conductor is a wire.
In at least one embodiment, the at least one conductor extends helically from the proximal end portion to the distal end portion of the lead body.
In at least one embodiment, multiple conductors are formed on the outside surface of the lead body.
In at least one embodiment, an electrically insulating layer is formed over at least a portion of the at least one conductor.
In at least one embodiment, the electrically insulating layer is not formed over the at least one conductor at at least one of the proximal end portion and the distal end portion of the lead body.
In at least one embodiment, an electrode is formed at at least one of the proximal end portion and the distal end portion of the lead body.
In at least one embodiment, a conductive band is formed around at least one of the proximal end portion and the distal end portion of the lead body.
In at least one embodiment, at least a portion of the insulating layer is stiffer than at least one other portion of the insulating layer.
In at least one embodiment, the at least one lumen has a rounded cross-sectional shape.
In at least one embodiment, multiple lumens extend longitudinally through the lead body.
In at least one embodiment, three lumens extend longitudinally through the lead body.
In at least one embodiment, at least one other conductor extends through the at least one lumen.
In at least one embodiment, at least one other conductor extends through the lead body.
These and other features of this invention are described in, or are apparent from, the following detailed description of various exemplary embodiments of this invention.
Various exemplary embodiments of this invention will be described in detail, with reference to the following figures, wherein:
The various exemplary embodiments of the present invention are directed to a catheter having conductors formed around the outside of the catheter body. Forming the conductors external to the catheter body diminishes the risk that the conductors will be damaged during bending and/or kinking of the catheter. Further, by arranging the conductors in specific configurations, such as, for example, a helical configuration, risk of damage can be diminished even further.
In the following detailed description, the terms “distal” and “proximal” will be used. As used herein, the term “proximal” refers to that region, portion or end of a device or procedure nearest the person using the device or performing the procedure, while the term “distal” refers to that region, portion or end of a device or procedure nearest a patient upon whom the device is being used or the procedure is being performed.
The lead body 10 may be made from a variety of sterilizable plastics known in the art, including, but not limited to, polyamides and copolymers thereof, low density polyethylene, high density polyethylene, polypropylene, polystyrene, polycarbonate, polytetrafluoroethylene, fluorinated ethylene propylene and polyurethane. The lead body 10 is preferably formed by extrusion.
Flexible electrical conductors 20, 22, 24 are formed around the outer surface of the lead body 10. Although the conductors 20, 22, 24 are shown helically arranged around the lead body 10, the conductors 20, 22, 24 may be configured in any way around the lead body 10, such as in a straight line or arranged in a circuit pattern. However, the conductors 20, 22, 24 are preferably helically arranged in a “barber-pole” configuration so that they are less likely to break upon bending or stretching. Further, multiple conductors are preferred to ensure that an electrical path exists even when one of the conductors is damaged. The conductors 20, 22, 24 may be made of any suitable electrically conducting material, such as, for example, Au, Ag, Pt, Ni and Cu. Further, although three conductors are shown in
The conductors 20, 22, 24 may be formed directly on the lead body by any suitable method, such as, for example, chemical vapor deposition, laser deposition, and photolithography techniques involving masking and spraying, brushing or dipping operations. Alternatively, each of the conductors 20, 22, 24 may be in the form of separate wires that are attached to the outer surface of the lead body 10 by a suitable adhesive.
The catheter 1 further includes an insulating layer 30 formed over the conductors 20, 22, 24. As shown in
In conventional catheters, a stylet wire is typically inserted into one of the lumens to stiffen and manipulate the catheter during implantation. In the present embodiment, the stiffness of the insulating layer 30 may be “tuned” so as to obviate the need for a stylet, such as by altering the catheter wall thickness and/or the catheter material along the length of the catheter. For example, the insulating layer 30 may be made stiffer at portions of the lead body 10 such as with a dual-durometer extrusion to diminish the risk of kinking and bending during insertion of the lead body 10 and to aid in manipulation of the lead body 10.
The conductors 20, 22, 24 may be attached to electrodes 32 formed at the exposed proximal and distal end portions of the lead body 10. Alternatively, as shown in
While particular embodiments of the present invention have been illustrated and described, it would be obvious to those skilled in the art that various other changes and modifications can be made without departing from the spirit and scope of the invention. For example, in other embodiments of the invention, conductors may be disposed within at least one of the lumens in addition to the conductors disposed on the outside of the lead body. It is therefore intended to cover in the appended claims all such changes and modifications that are within the scope of this invention.
