Patent Description:
A common interventional procedure in the field of pulmonary medicine is bronchoscopy, in which a bronchoscope is inserted into the airways through the patient's nose or mouth. The structure of a bronchoscope generally includes a long, thin, flexible tube that typically contains three elements: an illumination assembly for illuminating the region distal to the bronchoscope's tip via an optical fiber connected to an external light source; an imaging assembly for delivering back a video image from the bronchoscope's distal tip; and a lumen or working channel through which instruments may be inserted, including, but not limited to, placement instruments (e.g., guide wires), diagnostic instruments (e.g., biopsy tools) and therapeutic instruments (e.g., treatment catheters or laser, cryogenic, radio frequency, or microwave tissue treatment probes).

During some procedures (e.g., microwave ablation and biopsy), a catheter having an extended working channel may be inserted through a working channel to enable navigation to sites that are typically too remote, or have luminal diameters too small, for the bronchoscope. The catheter may have a locatable sensor at its distal end to assist in guiding the catheter to targeted tissue. When the distal end of the catheter is positioned adjacent targeted tissue, an instrument may be inserted through the extended working channel of the catheter to perform a procedure on the targeted tissue (e.g., perform a biopsy or ablation of the targeted tissue).

Presently, the sensor on the catheter is fabricated using a plurality of discreet wires that require a metal bonding connection. Since the distal end of the catheter is subjected to bending forces during use, the sensor and its connections experience strain.

patent document <CIT> discloses a flexible catheter including an elongated body and a sensor.

Accordingly, there is a need for catheters with a locatable sensor having a longer useful life.

According to the invention, a method of manufacturing a flexible catheter according to claim <NUM> is provided. Preferred embodiments of the invention are provided according to the dependent claims.

In some methods, the second portion of the wire may unravel from the second spool as the spool carrier is rotated.

Some methods may further include forming a second wrapping layer over the first wrapping layer with the second portion of the wire.

Some methods may further include axially moving the catheter body relative to the first and second spools while the drive motor is activated and the catheter body is rotated. Some methods may alternatively include axially moving the first and second spools relative to the catheter body while the drive motor is activated and the catheter body is rotated.

In some methods, the first and second spools may rotate about their respective longitudinal axes in response to the rotation of the catheter body.

In some methods, non-rotatably coupling the spool carrier to the catheter body may include capturing the catheter body within a channel defined through a length of an elongate body of the spool carrier. The first portion of the spool carrier may extend outwardly from the elongate body.

In some methods, non-rotatably coupling the spool carrier to the catheter body may further include fixing the elongate body of the spool carrier to the catheter body.

In some methods, the catheter body may include at least an inner liner. The inner liner may be disposed about a rotatable mandrel.

In some methods, the spool carrier may be rotated in response to a rotation of the mandrel.

Some methods may further include applying an adhesive to a plurality of locations of the twisted pair of the wire.

Further, to the extent consistent, any of the aspects described herein may be used in conjunction with any or all of the other aspects described herein.

Various aspects of the present disclosure are described hereinbelow with reference to the drawings, which are incorporated in and constitute a part of this specification, wherein:.

In the following reference is made to certain non-SI units ("inches"). These are to be converted to SI units ("mm") according to the following approximate factor:
<NUM> inch = <NUM>.

This disclosure relates generally to a method of forming a wire sensor on a catheter. The sensor is used for locating the distal end portion of an extended working channel ("EWC") of the catheter within the anatomy of a patient. A spool carrier assists in forming both a sensor on a distal end portion of the catheter and a twisted pair that extends proximally from the sensor along a proximal end portion of the catheter and connects to a flexible circuit pad.

Embodiments of the present disclosure are now described in detail with reference to the drawings in which like reference numerals designate identical or corresponding elements in each of the several views. As used herein, the term "clinician" refers to a doctor, a nurse, or any other care provider and may include support personnel. Throughout this description, the term "proximal" refers to the portion of the device or component thereof that is closest to the clinician and the term "distal" refers to the portion of the device or component thereof that is farthest from the clinician.

Referring now to <FIG>, a catheter assembly <NUM> is provided in accordance with the present disclosure and includes a handle assembly <NUM>, a telescopic channel <NUM>, and an elongated catheter body <NUM> having a proximal end portion <NUM> and a distal end portion <NUM>. The handle assembly <NUM> is coupled to the proximal end portion <NUM> of the catheter body <NUM> to permit a clinician to manipulate the catheter assembly <NUM>.

The telescopic channel <NUM> is positioned between the handle assembly <NUM> and the proximal end portion <NUM> of the catheter body <NUM> to provide lateral support for the catheter body <NUM>. The telescopic channel <NUM> includes a proximal or first end portion <NUM> that is coupled to a distal end portion <NUM> of the handle assembly <NUM> and a distal or second end portion <NUM> that is configured to couple the catheter assembly <NUM> to a bronchoscope (not shown). The telescopic channel <NUM> includes an extendable body portion <NUM> between the first and second end portions <NUM>, <NUM> that is expandable along a longitudinal axis and substantially rigid transverse to the longitudinal axis. The extendable body portion <NUM> allows the first end portion <NUM> to translate along and rotate about the longitudinal axis relative to the second end portion <NUM>. When the first end portion <NUM> is coupled to the handle assembly <NUM>, the proximal end portion <NUM> of the catheter body <NUM> translates and rotates with the first end portion <NUM> of the telescopic channel <NUM>.

With additional reference to <FIG>, the catheter body <NUM> defines an EWC <NUM> along a length thereof. The EWC <NUM> allows instruments (not shown) to be inserted through the catheter body <NUM> to treat targeted tissue adjacent the distal end portion <NUM> of the catheter body <NUM>. The catheter body <NUM> includes an inner liner <NUM>, a braid <NUM>, and an outer coating <NUM>. The inner liner <NUM> defines the EWC <NUM> that passes entirely through the catheter body <NUM>. It is contemplated that the catheter body <NUM> may be constructed without the inner liner <NUM> such that the braid <NUM> defines the EWC <NUM>.

With additional reference to <FIG>, as described in greater detail below, a sensor <NUM> is formed of one continuous wire <NUM> wrapped over the braid <NUM> and covered by the outer coating <NUM> to form the sensor <NUM>. The wire <NUM> includes leads 76a, 76b that are twisted together to form a twisted pair <NUM> that is coiled about the braid <NUM> along the proximal end portion <NUM> of the catheter body <NUM>. It will be appreciated that while the portions of the wire <NUM> (e.g., the leads 76a, 76b) are discussed individually herein, according to the invention the wire <NUM> is monolithically formed (i.e., the wire <NUM> is one continuous wire without any solder joints between different portions thereof). By forming the sensor <NUM> from one continuous monolithic wire <NUM>, the useful life of the sensor <NUM>, and thus the catheter body <NUM>, is increased.

The inner liner <NUM> and the outer coating <NUM> are formed from polymer tubes, as detailed below, which are made from of a reflowable polymer material (e.g., thermoplastic polymers or polytetrafluoroethylene (PTFE)) which may bond to the braid <NUM>, the wire <NUM>, and to one another. The braid <NUM> is constructed of a mesh of between <NUM> and <NUM> of similar or varying material cords woven together (e.g., stainless steel, polyethylene naphthalate (PEN), polyethylene terephthalate (PET), and/or insulated electrical wire). The wire <NUM> is a solid core magnetic wire with a thin dielectric coating (e.g., a copper wire with a polyimide coating).

With reference to <FIG> and <FIG>, a coil winding station <NUM> and a spool carrier <NUM> are utilized to form the catheter body <NUM> with the sensor <NUM>. The coil winding station <NUM> generally includes a mandrel <NUM>, a drive motor <NUM> operably coupled to a rotatable hub <NUM>, and a control system <NUM> (e.g., a computer) for operating the components of the coil winding station <NUM>. The hub <NUM> is configured to rotatably support first and second spools 130a, 130b thereon. The hub <NUM> rotates, in the direction indicated by arrow "A," in response to an activation of the drive motor <NUM>. A first end of the mandrel <NUM> is secured to a head stock chuck 108a, and a second end of the mandrel <NUM> is secured to a tail stock chuck 108b. The mandrel <NUM> is rotatable about its longitudinal axis via rotation of the head and/or tail stock chucks 108a, 108b.

<FIG> depicts the spool carrier <NUM>, which includes an elongate body <NUM> and a pair of portions or arms 124a, 124b extending perpendicularly from the elongate body <NUM>. In embodiments, the spool carrier <NUM> may only have one arm 124a or 124b. The elongate body <NUM> defines a channel <NUM> extending through a length thereof. The channel <NUM> is configured for receipt of the mandrel <NUM> or the catheter body <NUM>. The spool carrier <NUM> has a fastener, such as, for example, a screw <NUM> to secure the elongate body <NUM> to the catheter body <NUM> such that rotation of the catheter body <NUM> results in rotation of the spool carrier <NUM>. In embodiments, instead of using screw <NUM>, the elongate body <NUM> may be secured to the catheter body <NUM> using magnets, wire clips, detents, pins, adhesives, hook and loop fasteners, or the like. The arms 124a, 124b of the spool carrier <NUM> are disposed on opposite sides of the elongate body <NUM> and are each configured to couple to a respective spool 130a, 130b, such as, for example, bobbins.

With reference to <FIG>, a method of manufacturing the catheter body <NUM> will now be described. Initially, the inner liner <NUM> is slid over the mandrel <NUM>, which provides rigidity to the flexible components of the catheter body <NUM> while the catheter body <NUM> is being assembled. The inner liner <NUM> has an inner diameter substantially equal to but slightly larger than an outer diameter of the mandrel <NUM> and has a length substantially equal to a length of the mandrel <NUM>. The mandrel <NUM> may be coated with a PTFE coating to assist in sliding the inner liner <NUM> over the mandrel <NUM> and to prevent the inner liner <NUM> from bonding to the mandrel <NUM>. The outer diameter of the mandrel <NUM> is substantially equal to a desired diameter of the EWC <NUM> and the length of the mandrel <NUM> is longer than a final desired length of the catheter body <NUM>. The mandrel <NUM> may have a diameter in a range of about <NUM> to about <NUM> inches (e.g., about. <NUM> inches) and have a length in a range of about <NUM> to about <NUM> inches (e.g., about <NUM> inches).

The braid <NUM> of the catheter body <NUM> is formed over the inner liner <NUM> with portions of the braid <NUM> extending beyond the ends of the mandrel <NUM> such that the mandrel <NUM> and the inner liner <NUM> may be completely within the braid <NUM>. The braid <NUM> is formed by helically weaving cords <NUM> of material over a cylinder (e.g., the inner liner <NUM> and the mandrel <NUM>). The cords <NUM> define channels <NUM> therebetween that follow the helical pattern of the cords <NUM>. The pitch of the cords <NUM> may be in a range of about <NUM> to about <NUM> (e.g., about <NUM>). The braid <NUM> may compress the inner liner <NUM> over the mandrel <NUM>. The braid <NUM> may have an outer diameter in a range of about <NUM> to about <NUM> inches (e.g., <NUM> inches). It is contemplated that the inner liner <NUM>, the braid <NUM>, and the mandrel <NUM> may be supplied as a preassembled unit.

With reference to FIGs. <NUM>-<NUM>, a method of forming the sensor <NUM> on the catheter body <NUM> utilizing the coil winding station <NUM> and the spool carrier <NUM> will now be described. Formation of the sensor <NUM> generally includes wrapping the wire <NUM> over the braid <NUM> of the catheter body <NUM> to form two wrapping layers 72a, 72b (<FIG>) over the distal end portion <NUM> of the catheter body <NUM>, and then twisting together leads 76a, 76b of the wire <NUM> while wrapping the twisted leads 76a, 76b around the proximal end portion <NUM> of the catheter body <NUM>. In some methods, the wire <NUM> may be wrapped over the inner liner <NUM>, the PTFE liner, the outer coating <NUM>, or any other suitable portion of the catheter body <NUM>.

With reference to <FIG>, the wire <NUM> has a first end portion 71a wrapped about the first spool, and a second end portion 71b wrapped about the second spool 130b. The first spool 130a is positioned on the first arm 124a of the spool carrier <NUM>, and the second spool 130b is positioned on the hub <NUM> of the coil winding station <NUM>. The first spool 130a is prevented from rotating relative to the first arm 124a of the spool carrier <NUM> via a fastener <NUM> (e.g., a set screw or a thumb screw). The second spool 130b is free to rotate relative to the hub <NUM> about a longitudinal axis defined by the second spool 130b.

The inner liner <NUM> with braid <NUM> of the catheter body <NUM> is disposed on the mandrel <NUM> of the coil winding station <NUM>. An intermediate portion 71c of the wire <NUM> is laid transversely over the distal end portion <NUM> of the catheter body <NUM> (e.g., the inner liner <NUM> or PTFE coating) and routed through a wire guide <NUM> of the coil winding station <NUM>, as shown in <FIG>. The intermediate portion 71c of the wire <NUM> is adhered to the distal end portion <NUM> of the catheter body <NUM> using a UV cure adhesive or a piece of tape. In embodiments, the intermediate portion 71c of the wire <NUM> may be secured to the distal end portion <NUM> of the catheter body <NUM> via any suitable fastening mechanism. For example, the wire <NUM> may include a bondable coating that is heat or solvent activated.

The catheter body <NUM> is fixed to the mandrel <NUM> between the head and tail stocks 108a, 108b. The catheter body <NUM> is captured in the channel <NUM> of the spool carrier <NUM> to non-rotatably couple the spool carrier <NUM> with the catheter body <NUM> and mandrel <NUM>. In embodiments, the spool carrier <NUM> may be non-rotatably coupled directly to the mandrel <NUM> rather than the catheter body <NUM>.

With the intermediate portion 71c of the wire <NUM> fixed to the catheter body <NUM>, the spool carrier <NUM> is rotated approximately ½ turn to wrap the wire <NUM> once about the catheter body <NUM>, as shown in <FIG>. The mandrel <NUM> is positioned in a mandrel guide <NUM> to support the mandrel <NUM>, as shown in <FIG>. The mandrel <NUM> is rotated at a predetermined rate, and in turn, the catheter body <NUM> rotates about a longitudinal axis defined by the catheter body <NUM>. Since the spool carrier <NUM> is non-rotatably coupled to the catheter body <NUM>, the spool carrier <NUM> rotates with the catheter body <NUM>. Rotation of the spool carrier <NUM> pulls the second end portion 71b of the wire <NUM> to unravel the second end portion of 71b of the wire <NUM> from the second spool 130b.

Simultaneously with the rotation of the spool carrier <NUM>, the catheter body <NUM> is moved proximally relative to the second spool 130b at a predetermined rate, whereby the second end portion 71b of the wire <NUM> wraps about the distal end portion <NUM> of the catheter body <NUM> in a distal direction forming a first wrapping layer 72a, as shown in <FIG>. In some embodiments, instead of the catheter body <NUM> being moved axially relative to the second spool 130b, the second spool 130b is moved axially relative to the catheter body <NUM>.

Upon the first wrapping layer 72a achieving a suitable length on the distal end portion <NUM> of the catheter body <NUM>, a piece of tape (e.g., cellophane tape) or adhesive is applied to the inner liner <NUM> distal to the first wrapping layer 72a at a distance equal to approximately <NUM> or <NUM> diameters of the first wrapping layer 72a. The catheter body <NUM> is moved distally at the predetermined rate, or in some embodiments another predetermined rate, to form a second wrapping layer 72b (<FIG> and <FIG>) over the first wrapping layer 72a.

Each of the first and second wrapping layers 72a, 72b may include a range of about <NUM> to about <NUM> individual wraps or loops <NUM> (e.g., about <NUM> individual wraps) of the wire <NUM>. The number of wraps <NUM> in the first wrapping layer 72a may be substantially equal to the number of wraps <NUM> in the second wrapping layer 72b. As shown, the sensor <NUM> includes two wrapping layers 72a, 72b; however, it is contemplated that the sensor <NUM> may include a single wrapping layer or may include more than two wrapping layers. The number of wrapping layers of the wire <NUM> is proportional to signal strength of the sensor <NUM> (i.e., as the number of wrapping layers increases, the signal strength of the sensor <NUM> increases). As the number of wrapping layers is increased, the flexibility of the catheter body <NUM> in the area of the wrapping layers is reduced and the diameter of the catheter body <NUM> in the area of the wrapping layers is increased.

The total length of the wrapping layers 72a, 72b is in a range of about <NUM> to about <NUM> inches (e.g., about <NUM> inches). As the total length of the wrapping layers 72a, 72b is increased, the flexibility of the catheter body <NUM> in the area of the wrapping layers is reduced. Thus, the number wrapping layers, the length of the wrapping layers, and the total number of wrapping layers is a compromise between the signal strength of the sensor <NUM> and the flexibility and size of the catheter body <NUM>.

In embodiments, a support tube or layer may be positioned over the braid <NUM> before the wire <NUM> is wrapped over the braid <NUM> to form the wrapping layers 72a, 72b of the sensor <NUM>. The support layer may be a ferro-metallic tube or a powder with resin that is configured to strengthen or support the sensor <NUM> to prevent the sensor <NUM> from deforming when used. The support layer may increase the signal strength of the sensor <NUM> such that the length and/or number of wrapping layers required to achieve a desired signal strength for the sensor <NUM> may be reduced.

Upon forming the first and second wrapping layers 72a, 72b, adhesive is applied to the entire length or substantially the entire length of the wrapping layers 72a, 72b to secure the wire <NUM> to the distal end portion <NUM> of the catheter body <NUM>. As shown in <FIG>, the wire <NUM> is removed from the wire guide <NUM>, and as shown in <FIG>, the first spool 130a is removed from the spool carrier <NUM>, and the spool carrier <NUM> is detached from the catheter body <NUM>. The first spool 130a is operably coupled to the hub <NUM>, adjacent the second spool 130b, as shown in <FIG>. As shown in <FIG>, the lead wires 76a, 76b are positioned in a twisting guide <NUM> of the coil winding station <NUM> and aligned with one another so as to extend from the same location of the catheter body <NUM>.

The drive motor <NUM> is activated to rotate the hub <NUM> on which the first and second spools 130a, 130b are coupled, and in turn, the first and second spools 130a, 130b rotate about a common axis defined by the drive motor <NUM>. As the spools 130a, 130b rotate about the common axis, the first and second leads 76a, 76b of the wire <NUM>, which extend between the first and second spools 130a, 130b and the wrapping layers 72a, 72b, twist together to form a twisted pair <NUM> (<FIG>) of the wire <NUM>. The hub <NUM> is rotated a predetermined number of turns to yield a suitable number of wire twists per inch along the length of the twisted pair <NUM> of the wire <NUM>. The leads 76a, 76b may be twisted together in a range of about <NUM> to about <NUM> twists per inch (e.g., about <NUM> twists per inch) of the wire <NUM>. Forming a twisted pair <NUM> reduces or eliminates a signal from being generated by the wire <NUM> along the length of the braid <NUM> (i.e., utilizing the constructive interference to minimize the signal generated).

Simultaneously with the rotation of the hub <NUM> by the drive motor <NUM>, the catheter body <NUM> is rotated about its longitudinal axis, thereby exerting a proximally-oriented pulling force on the ends of the first and second leads 76a, 76b. The pulling force exerted on the leads 76a, 76b by the rotation of the catheter body <NUM> drives a rotation of the first and second spools 130a, 130b about their respective longitudinal axes and relative to the hub <NUM>. Rotation of the first and second spools 130a, 130b about their respective axes allows the leads 76a, 76b to unravel therefrom, causing the twisted pair <NUM> to wrap around the catheter body <NUM>. In this way, the twisted pair <NUM> of the wire <NUM> is coiled about the proximal end portion <NUM> of the catheter body <NUM> as the twisted pair <NUM> is forming. As can be appreciated, there is a delay (e.g., for approximately <NUM> second) between the start of rotation of the hub <NUM> and the start of rotation of the catheter body <NUM>.

Simultaneously with the rotation of the hub <NUM> and the rotation of the catheter body <NUM>, the hub <NUM> with the spools 130a, 130b are moved axially along a track (not shown) relative to the catheter body <NUM>. By axially moving the hub <NUM> relative to the catheter body <NUM> as the catheter body rotates, the coil of wire <NUM> that forms about the catheter body <NUM> assumes a helical pattern about the proximal end portion <NUM> of the catheter body <NUM> along its length, as shown in <FIG>. The helical pattern of the coil has a predetermined pitch based on the ratio of the rate of rotation and axial movement of the catheter body <NUM>. In some embodiments, instead of axially moving the hub <NUM> axially relative to the catheter body <NUM>, the catheter body <NUM> may be axially moved relative to the hub <NUM>/first and second spools 130a, 130b.

Upon coiling the twisted pair <NUM> of the wire <NUM> about the catheter body <NUM>, the twisted pair <NUM> may be adhered to the catheter body <NUM> using an adhesive, such as, for example, a cyanoacrylate adhesive, applied to a plurality of locations along the length of the catheter body <NUM>, as shown in <FIG>. After the twisted pair <NUM> of the wire <NUM> is formed, the ends of the leads 76a, 76b are severed from the remaining portions of the wire <NUM> wrapped about the first and second spools 130a, 130b. With the twisted pair <NUM> coiled about the braid <NUM> of the catheter body <NUM>, a cover (e.g., a polyamide cover) may be applied over the twisted pair <NUM>.

After formation of the sensor <NUM> and coiling the twisted pair <NUM> about the catheter body <NUM>, the outer coating <NUM> of the catheter body <NUM> may be slid over or applied to the braid <NUM> until a proximal end of the outer coating <NUM> is adjacent to the proximal ends of the twisted pair of leads 76a, 76b. The outer coating <NUM> may be a polymer tube which is then covered by heat shrink to melt or reflow the polymer such that the outer coating <NUM> reflows or bonds to the braid <NUM>. In addition, when the outer coating <NUM> is reflowed, the inner liner <NUM> within the outer coating <NUM> may be reflowed to bond with the braid <NUM> and the outer coating <NUM>. The proximal end of the leads 76a, 76b may be electrically connected (e.g., via solder) to a flexible circuit pad (not shown) to connect to the sensor <NUM>. Other metal bonds may be used to connect leads 76a, 76b to the sensor <NUM>, such as, for example, brazing, swaging, or an ultrasonic/laser/resistance weld.

Forming the wrapping layers 72a, 72b of the sensor <NUM> and the twisted pair <NUM> with a single continuous wire <NUM> increases the service life of the catheter body <NUM> by eliminating the need for a connection (e.g., a soldered connection) between the wrapping layers 72a, 72b and each of the twisted pair of leads 76a, 76b.

In some embodiments, the wrapping layers 72a, 72b of the sensor <NUM> and the twisted pair <NUM> may be preformed apart from the catheter body <NUM> and then positioned or loaded over the catheter body <NUM>, e.g., the braid <NUM> or the inner liner <NUM> of the catheter body <NUM>. In another embodiment, the wrapping layers 72a, 72b of the sensor <NUM> may be preformed and then loaded over the braid <NUM> of the catheter body <NUM>, followed by wrapping the twisted pair <NUM> about the braid <NUM> using one of the methods detailed above.

For a more detailed description of the construction of various components of the catheter assembly <NUM>, reference may be made to <CIT>.

Claim 1:
A method of manufacturing a flexible catheter (<NUM>) with a locatable sensor (<NUM>), the method comprising:
(a) non-rotatably coupling a first spool (130a) to a first portion of a spool carrier (<NUM>), a first portion (71a) of a single monolithic wire (<NUM>) being wrapped about the first spool and a second portion (71b) of the wire being wrapped about a second spool (130b);
non-rotatably coupling the spool carrier (<NUM>) to a catheter body (<NUM>);
routing the wire (<NUM>) through a wire guide (<NUM>) and positioning the wire (<NUM>) across an outer surface of the catheter body (<NUM>) prior to rotating the spool carrier;
rotating the spool carrier (<NUM>) with the catheter body, thereby wrapping the second portion (71b) of the wire about a distal end portion (<NUM>) of the catheter body (<NUM>) to form a first wrapping layer (72a) of the sensor (<NUM>) at the distal end of the catheter;
(b) coupling the first spool (130a) and the second spool (130b) to a drive motor (<NUM>); and
simultaneously:
activating the drive motor to rotate the first and second spools (130a, 130b) about a common axis, whereby first and second leads (76a, 76b) corresponding to each free end of the wire (<NUM>) of the first wrapping layer (72a) twist together to form a twisted pair (<NUM>) of the wire; and
rotating the catheter body (<NUM>) about a longitudinal axis defined by the catheter body, whereby the twisted pair (<NUM>) of the wire wraps about a proximal end portion of the catheter body.