Surgery: light – thermal – and electrical application – Light – thermal – and electrical application – Electrical energy applicator
Reexamination Certificate
1997-08-26
2001-06-19
Evanisko, George R. (Department: 3762)
Surgery: light, thermal, and electrical application
Light, thermal, and electrical application
Electrical energy applicator
Reexamination Certificate
active
06249708
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to transvenous catheter electrical leads for use with pacemakers, defibrillators and other tissue stimulating devices. More particularly, the present invention relates to a fluted channel construction for a multi-conductor lead in which the elongated conductors are carried within fluted channels defined around the peripheral surface of an elongated inner body member that is then surrounded by an outer insulative sheath member.
BACKGROUND OF THE INVENTION
Transvenous catheter electrical leads are used with pacemakers, defibrillators and other tissue stimulating devices to deliver electrical stimulation to a desired portion of the body. A transvenous lead is designed to access the desired portion of the body by routing the lead through a vein. The leads are comprised of an elongated tubular body made of a biocompatible, insulative material with one or more elongated conductors inside the lead body. The conductors are connected to an associated electrode located somewhere on the outside of the lead body, either along the body or at the distal end. The conductors are also connected to an associated connector at the proximal end of the lead body. The original transvenous catheter lead for an implantable defibrillator system is described in U.S. Pat. No. 3,942,536 to Mirowski et al.
Typically, a transvenous lead will have more than one electrode and, hence, more than one conductor. While there are numerous ways to construct and attach the electrodes on a multiple conductor lead, the basic construction of existing leads in terms of the arrangement of conductors within the lead can be characterized either as: (1) coaxial, (2) multi-lumen, or some combination of these two constructions. In a coaxial arrangement, each of the conductors is a hollow tube of a different size, with one tube positioned inside the other (i.e., the tubes are coaxial with each other). In a multi-lumen arrangement, each of the conductors is carried in a separate tubular passageway (i.e., lumen) internal to the body of the catheter.
It will be apparent that, as the number of desired conductors is increased, the overall diameter of a transvenous lead increases. In a coaxial arrangement, each new conductor increases the diameter of the lead by at least two times the thickness of the walls of the hollow conductor, as well as the insulation material used to separate the conductors from one another. Examples of coaxial conductor arrangements are shown in U.S. Pat. Nos. 4,355,646, 4,630,611 and 5,456,707 (showing multiple conductors helically wrapped together along a central axis) and U.S. Pat. No. 4,947,866 (showing a center conductor around which a multi-stranded second conductor is wrapped). In a multi-lumen arrangement, the overall increase in the diameter of the lead can sometimes be less than the diameter of the added conductor if the conductors are optimally arranged within the interior space of the insulative lead body. The challenge in increasing the number of conductors in a multi-lumen arrangement is the need for more lumens internal to the lead body countered by the desire to keep the overall diameter of the lead body as small as possible. Examples of multi-lumen conductor arrangements are shown in U.S. Pat. No. 5,209,229 (showing a polyurethane tube catheter lead having one large lumen and two smaller lumens) and U.S. Pat. No. 5,628,778 (showing a quadramulen silicon sleeve used for a single pass lead). U.S. Pat. No. 5,545,203 shows a multilumen lead with additional material surrounding each conductor in the area of the first clavicle rib to serve as a crush resistant protection. A combination of a coaxial and lumen configuration is shown in U.S. Pat. No. 4,627,439 which discloses a preshaped polyurethane tube which includes three coiled conductors helically wound around each other within the lumen of an outer coaxial conductor. A different approach to solving the problem of increased conductors and electrodes is taught by U.S. Pat. No. 5,235,870 which discloses a multiplexing arrangement to keep the number of conductors constant while allowing for an increase in the number of electrodes carried by the lead.
While existing techniques for constructing multi-conductor transvenous leads have been acceptable to date because the number of conductors in such leads has been relatively small (e.g., three or less), there is a need for better multi-conductor transvenous leads which can more easily accommodate larger numbers of conductors.
SUMMARY OF THE INVENTION
The present invention is a multi-conductor fluted channel construction catheter lead comprised of an elongated flexible tubular inner body member having a peripheral surface around which a plurality of longitudinally-oriented fluted channels are defined. A plurality of conductors are provided with at least one conductor being disposed within one of the fluted channels and operably connected at a distal portion to an electrode and at a proximal portion to a connector. An outer insulative sheath member surrounds the inner body member and the conductors. A method of constructing a fluted channel catheter lead is also disclosed.
Preferably, the multi-conductor catheter lead has at least one fluted channel which is open to serve either as a crush zone or as a channel for inserting a stiffening material to shape the catheter lead. In the preferred embodiment in which the catheter lead is constructed of a flexible medical grade silicon rubber material, the ability of the fluted channels to serve as mechanisms for inserting a stiffening material to shape the catheter lead provide a significant advantage. Unlike prior catheter leads which were preshaped, the present invention does not require that the polymer material of the body of the catheter lead be a thermoset plastic material, such as polyurethane, in order for the body of the catheter lead to retain a preshaped configuration. Nor does it require that the electrodes and/or conductors be preshaped in order to force the body of the catheter lead into a preshaped configuration. Preferably, a portion of the open channels can be used to create transition zones within the lead whereby any flexing stress on critical areas, such as terminations of the conductor to an electrode, can be longitudinally translated to the edge of the transition zone.
In one embodiment of the present invention, an equal number of open channels and conductor channels are arranged around the peripheral surface of the inner body member. Preferably, the channels are arranged with an equal number of conductor carrying channels and empty channels, and all of the channels are longitudinally spiraled or twisted along the peripheral surface of the inner body member to further reduce stress on the lead conductors. The arrangement and configuration of the channels can take any number of forms. The inner body can also be provided with a center lumen that can contain an additional conductor and serve as a lumen for a stylet. By providing for multiple conductors within the fluted channels of the inner body, the catheter lead also allows for improvements in construction of the lead and connection between the conductors and the electrodes.
In an alternate embodiment of the present invention, a multi-conductor catheter lead includes an elongated flexible tubular inner body member having a plurality of longitudinally-oriented channels defined therein with a plurality of electrodes located along a distal portion of the lead. Each electrode surrounds a portion of the inner body member. A conductor disposed within one of the plurality of channels is operably connected at a distal portion of the conductor to one of the electrodes and at a proximal portion of the conductor to a connector. At least two outer insulative members surround the inner body member, each member surrounding a longitudinal segment of the lead between electrodes. Each outer insulative member abuts at least one of the electrodes and has a radial depth substantially equal to a radial depth of the abutted electrode such that the electrode is
Dahl Roger
Nelson Randy S.
Zytkovicz Duane
Angeion Corporation
Evanisko George R.
Patterson Thuente Skaar & Christensen P.A.
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