Patent Description:
Catheter introducer systems are often introduced into blood vessels and organs for intraluminal diagnostics, treatment and delivery of medical devices and structures. The type of catheter introducer system utilized depends on the medical procedure performed, the route in the body taken, and individual patient anatomy, among other factors. A tortuous blood vessel refers to a blood vessel that is particularly difficult to advance an intraluminal device through, such as a catheter introducer system, usually due to tight and/or reverse bends defined by the path of the blood vessel. An example of a procedure that traverses particularly tortuous blood vessels is where transvenous access to the main pulmonary artery is desired from the femoral vein.

Dilators are used to expand narrowed blood vessels and/or to enable the introduction of a larger diameter intraluminal device. Dilators are limited in their ability to navigate tortuous bends. Where a guidewire may be able to traverse a particular bend, a dilator and sheath system may not be able to track over the guidewire and traverse the particular bend. Prior art dilator and sheath systems are designed to be advanced as a single unit. This method of operation, combined with dilators not substantially longer than their associated sheath, results in an abrupt transition in bending stiffness from the guidewire to the dilator and sheath system. The guidewire may be deflected out of position by the dilator and sheath instead of the guidewire presenting itself as a stable track path. Further, the tip of the sheath may abut and damage the blood vessel. What is needed in the art is a dilator system capable of traversing tortuous blood vessels, and a catheter introducer system including the dilator system that is capable of traversing tortuous blood vessels.

<CIT> discloses a dilator including a shaft, a lumen and a hub. The shaft has at least two stiffness sections with the stiffness sections becoming less rigid as they approach a distal end of the shaft. The dilator may also taper at the distal tip to stretch the initial skin puncture hole larger to accommodate the dilator shaft and ease the sheath tip insertion through the vasculature. Alternatively, the shaft may taper from where it extends beyond the sheath distal tip to the distal end so that it can reach further distal in the vasculature. The dilator may also include an atraumatic tip for easier advancement of the dilator. The dilator distal end may also include one or more radiopaque markers and a shaped distal end.

<CIT> discloses an internal compression tourniquet catheter system and method for controlling hemorrhage from wounds, particularly penetrating wounds. Its construction includes an inflatable member constructed of very thin, flexible, biocompatible, and nonelastic and puncture resistant material such that when deflated it lies flat and can be wrapped around the catheter shaft, which passes within and has a lumen to inflate it, to minimize overall diameter when deflated for insertion into the tissue tract created by the wounding agent. The inflatable member is of large potential volume enabling full inflation with near zero internal pressure when unconstrained internally. The catheter system includes means to assist insertion into the wound track, including a rounded or bulbous exploring tip and an internal stylet with an external orientable handle. The distal end of the catheter stylet assembly can be bent slightly to allow following a curved or irregular wound track, such wound track navigation further assisted by twisting the stylet handle to orient the bent catheter tip within the wound track. <CIT> discloses a resiliently flexible body vessel or body cavity dilator that tapers towards one end and a transition zone that decreases in flexibility along the dilator away from the one end. The dilator can comprise a dilator arranged to be slid over a guidewire for use in the placement of an intraluminal graft bridging an aortic aneurysm.

<CIT> discloses a transseptal guidewire for perforating the intra-atrial septum of the heart are disclosed. The transseptal guidewire has an elongated body, an end section biased in a curved configuration to define a proximal curve, and a distal section biased in a curved configuration to define a distal curve, the distal curve being oriented in a direction generally opposite that of the proximal curve.

The invention defines a catheter introducer system for accessing a blood vessel according to claim <NUM>. Several embodiments are defined in claims <NUM>-<NUM>.

In particular, there is provided a catheter introducer system for accessing a blood vessel comprising:.

The accompanying drawings are included to provide a further understanding of the present disclosure and are incorporated in and constitute a part of this specification, illustrate embodiments described herein, and together with the description serve to explain the principles discussed in this disclosure.

It should be noted that the accompanying drawing figures referred to herein are not necessarily drawn to scale, but may be exaggerated to illustrate various aspects of the present disclosure, and in that regard, the drawing figures should not be construed as limiting.

Embodiments provided herein relate to dilators and catheter introducer systems that allow transvenous access to the main pulmonary artery from the femoral vein but can be applied in any situation involving access through tortuous blood vessels. Embodiments of a dilator system include a dilator and one or more cores that are operable to impart a predetermined curve to the dilator. Embodiments utilize one or more cores that are operable to be inserted within a dilator lumen of the dilator to alter or impart one or more curves in a dilator distal end.

Further, embodiments of a catheter introducer system are provided that include a dilator and one or more cores that are operable to impart a predetermined curve to the dilator over which a sheath of a catheter introducer system may traverse.

Further, embodiments of a sheath of a catheter introducer system are provided comprising a relatively more stiff sheath distal tip as compared with the rest of the sheath distal end. A more stiff sheath distal tip reduces ovalization of the sheath distal tip as the sheath distal tip traverses a curve induced by a core so as to prevent damage to the blood vessel.

As used herein, "blood vessel" refers to not only an element of the vasculature, but any blood conduit of the cardiovascular system, including the heart.

As used herein, a "tortuous" blood vessel refers to a blood vessel that is particularly difficult to advance an intraluminal device through usually due to tight and/or reverse bends defined by the path of the blood vessel. An example of a procedure that traverses particularly tortuous blood vessels is where transvenous access to the main pulmonary artery is desired from the femoral vein.

As used herein, "dilator" refers to an elongated tubular member that may be used to enlarge or stretch a body part, such as a blood vessel, cavity, canal, or orifice. A dilator may be used to introduce and guide a sheath into and through a blood vessel. A dilator is relatively less stiff than a sheath in accordance with constructs presented therein.

As used herein, "lumen" refers to a longitudinal cavity or through-bore along the longitudinal axis in a tubular component. A lumen may extend partially, completely or substantially the axial length of a component, such as a dilator, sheath or core, for example.

As used herein, "assembly" or "introducer assembly" refers to two or more components of a catheter introducer system, such as combinations of dilators, sheaths, guide wires and cores.

As used herein, "shaped" refers to a component formed to a predetermined pattern, geometry, curvature or angle. Cores or dilators may be shaped such as to conform to or follow a particular form or pattern. Cores or dilators may include curves in one or more planes and/or in three-dimensional configurations. Cores may also be straight and used only to impart a desired level of stiffness to the system.

As used herein, "core" refers to an elongated tubular member capable of being received within a dilator lumen so as to impart a desired shape and/or stiffness to the dilator. The core can be manufactured of any material possible of forming and supporting a curve, such as, but not limited to, a metal, thermoplastic or molded or cast thermoset material. Nylon is an example of a material that may be used to form a core. Stainless steel and nitinol are examples of metals that may be used to form a core.

As used herein, "sheath" refers to a relatively more stiff, relative to a dilator, elongated tubular member operable for providing a guide way or conduit for introducing medical devices such as catheters into the body. A system utilizing a sheath advanced over a dilator is often used. The sheath may be positioned within the body with the assistance of a dilator.

As used herein, "curve" and "curvature" refer to a shape, geometry or radius of a component, such as a core or dilator. The curve of a component may be formed in one or more planes or in three-dimensional configurations and each component (e.g., dilator or core) can include none (straight), one, or more than one curve.

As used herein, "bend" refers to a change of direction of the path defined by a blood vessel, organ or other body cavity.

As used herein, "stiffness" refers to the property of a component to resist bending. A core may be used to provide a system with increased stiffness as compared with the stiffness of the individual components making up the system. For example, advancing a relatively stiff core within a dilator lumen of a relatively less stiff dilator will provide a core/dilator assembly with a higher stiffness than the dilator itself.

As used herein, "guidewire" refers to a wire or small diameter elongated member that may be advanced through a blood vessel or cavity of the body.

As used herein, "distal" refers to a region or location positioned away from a point of origin or attachment.

As used herein, "proximal" refers to a region or location positioned adjacent or near a point of origin or attachment.

As used herein, "tapered" refers to a change in physical dimension along a length of a component.

As used herein, "elongated" refers to a region of extended length.

As used herein, "radiopaque marker" refers to an element that resists the passage of x-ray or other electromagnetic radiation for at least the purpose of monitoring positioning using x-ray techniques.

As used herein, "interchangeably" refers to two or more components that can replace one another in a similar position or function. For example, two or more cores may be interchangeable within a dilator to impart differing curves onto the dilator.

<FIG> shows an exploded cross-sectional view of various systems all of which comprise a dilator <NUM> and a core <NUM>, and with or without additional components such as a guidewire <NUM> and a sheath <NUM>, in accordance with various examples. In the embodiments provided herein, the dilator <NUM> and core <NUM> are provided and used together as a dilator system <NUM>. The dilator <NUM> and core <NUM> are also a part of a larger system and used to facilitate the use of a sheath <NUM> which is supplied to define a catheter introducer system <NUM>. comprising the dilator <NUM>, the core (<NUM>) and the sheath <NUM>. Also, a guidewire <NUM> may or may not be provided and used to define a catheter introducer guidewire system <NUM>. Various combinations of systems comprising the dilator <NUM> and the core <NUM> as common components are provided below.

<FIG> shows an exploded cross-sectional view of a dilator system <NUM> comprising a core <NUM> and a dilator <NUM>, in accordance with an example. The core <NUM> is an elongated tubular member that is operable to be advanced within the dilator <NUM> as will be detailed below. The dilator <NUM> is an elongated tubular member that is operable to accept the core <NUM> therein and to allow the core <NUM> to advance at least partially within the dilator <NUM>. As will be provided below, one or more cores <NUM> having different characteristics may be provided in accordance with embodiments which are operable to impart characteristics to the dilator <NUM>.

<FIG> also shows an exploded cross-sectional view of a catheter introducer system <NUM> comprising the dilator system <NUM> and a sheath <NUM>, in accordance with an embodiment. The sheath <NUM> is an elongated tubular member having a sheath proximal end <NUM> and a sheath distal end <NUM> opposite from the sheath proximal end <NUM>. The sheath <NUM> further includes a sheath lumen <NUM> extending from the sheath proximal end <NUM> to the sheath distal end <NUM>, therethrough. The sheath lumen <NUM> defines a diameter that is operable to slidingly receive the dilator <NUM> therein and to allow the sheath <NUM> to advance over the dilator <NUM>.

<FIG> also shows an exploded cross-sectional view of a catheter introducer guidewire system <NUM> comprising the catheter introducer system <NUM>, and a guidewire <NUM>, in accordance with an example. The guidewire <NUM> is an elongated member that is operable for traversing tortuous blood vessels. Guidewires are well known in the art. The core <NUM> including the core lumen <NUM> is operable to be advanced over the guidewire <NUM> as will be detailed below. Also, the dilator <NUM> including the dilator lumen <NUM> is operable to be advanced over the guidewire <NUM> as will be detailed below.

<FIG> also shows an exploded cross-sectional view of a dilator guidewire system <NUM> comprising the dilator system <NUM> and a guidewire <NUM>, in accordance with an example. The core <NUM> including the core lumen <NUM> is operable to be advanced over the guidewire <NUM> as will be detailed below. Also, the dilator <NUM> including the dilator lumen <NUM> is operable to be advanced over the guidewire <NUM> as will be detailed below.

The dilator system <NUM> will be discussed below. As referred, the dilator system <NUM> comprises a core <NUM> and a dilator <NUM>, as represented in <FIG>. The core <NUM> is used in cooperative engagement with the dilator <NUM> to assist the passage of the dilator <NUM> through bends of a blood vessel.

The dilator <NUM> is an elongated tubular member having a dilator proximal end <NUM> and a dilator distal end <NUM> opposite from the dilator proximal end <NUM>. The dilator <NUM> further includes a dilator lumen <NUM> extending from the dilator proximal end <NUM> to the dilator distal end <NUM>, therethrough. The dilator lumen <NUM> defines a diameter that is operable to slidingly receive the core <NUM> therein and allow the core <NUM> to be advanced at least partially within the dilator lumen <NUM>.

By way of example, in accordance with an embodiment, the dilator <NUM> includes a dilator lumen <NUM> with a diameter of about <NUM> to about <NUM>, about <NUM> to about <NUM> or about <NUM> to about <NUM>.

The dilator <NUM> may be manufactured of any suitable material for the particular purpose, such as, but not limited to, a thermoplastic. The dilator <NUM> comprises a material property with sufficient stiffness to enlarge the blood vessel but not so stiff to damage the blood vessel or not be able to be guided within bends of the blood vessel by the core <NUM>.

Referring to <FIG>, which shows a side view of the dilator <NUM>, the dilator distal end <NUM> may include a dilator distal tip <NUM>. The dilator distal tip <NUM> may be an integral element of the dilator distal end <NUM> or an element that is coupled to the dilator distal end <NUM>. The dilator distal tip <NUM> may be tapered. In accordance with an embodiment, the dilator distal tip <NUM> defines a dilator tip lumen comprising a diameter that is less than a diameter of the core <NUM> whereby preventing the core <NUM> from extending beyond the dilator distal tip <NUM>. The lumen of the dilator distal tip <NUM> may also be tapered to a smaller diameter than the diameter of the core <NUM>, as shown in <FIG> and <FIG>, such that the core may not exit the dilator distal tip <NUM>, thus preventing the core <NUM> from injuring the blood vessel.

A dilator <NUM> may be formed by any suitable process, such as, but not limited to extrusion. The dilator distal tip <NUM> may be formed by any suitable process, such as, but not limited to, injection molding. The dilator distal tip <NUM> and dilator distal end <NUM> may be joined by any suitable process, such as, but not limited to thermal and chemical bonding. A dilator distal tip <NUM> that is coupled to the dilator distal end <NUM> may facilitate the production of a dilator distal tip <NUM> with a lumen that is tapered to a smaller diameter than the diameter of the core <NUM>, as shown in <FIG> and <FIG>. The dilator distal tip <NUM> may also be formed on the dilator distal end <NUM> as a one-piece component by any suitable process, such as, but not limited to grinding.

In accordance with embodiments, the dilator distal tip <NUM> has a length of about <NUM> to about <NUM>, about <NUM> to about <NUM> or about <NUM> to about <NUM>. The dilator distal tip <NUM> may be elongated to allow for greater adaptability with the core <NUM> and work in conjunction with the elongated dilator distal region <NUM>, as will be discussed below. The dilator distal tip <NUM> may or may not be tapered, but in most embodiments, a taper is provided on the outer diameter of the dilator distal tip <NUM> so that the blood vessel <NUM> is not exposed to steps and edges, and the lumen of the dilator distal tip <NUM> is tapered to a smaller diameter than the outer diameter of the core <NUM> thus preventing the core <NUM> from extending beyond the dilator distal tip <NUM> and possibly injuring the blood vessel.

The dilator <NUM> may include a radiopaque marker, such as, but not limited to an element that is coupled to the dilator <NUM> or by integrating doping materials into the construct, such as, but not limited to, barium sulfate.

Referring again to <FIG>, the core <NUM> is an elongated tubular member having a core proximal end <NUM> and a core distal end <NUM> opposite from the core proximal end <NUM>. The core <NUM> further includes a core lumen <NUM> extending from the core proximal end <NUM> to the core distal end <NUM>, therethrough. The core lumen <NUM> defines a diameter that is operable to slidingly receive a guidewire <NUM> therein and to allow the core <NUM> to advance over the guidewire <NUM>. The core <NUM> defines an outer diameter operable to be slidingly received within the dilator lumen <NUM> and to allow the core <NUM> to advance at least partially within the dilator lumen <NUM>.

Although the core <NUM> is shown as an elongated tubular member including a core lumen <NUM>, it is appreciated that for systems and uses that do not involve a guidewire <NUM> or other need for a lumen, such as, but not limited to irrigation, the core <NUM> may be an elongated member not having a lumen therethrough. In the discussion of the embodiments provided below, the core <NUM> will comprise a core lumen <NUM>, but will not be limited thereto. It is appreciated that for most uses, a guidewire <NUM> will be used with or as part of the system including a dilator <NUM> and core <NUM>. By way of example, in accordance with an example, the core lumen <NUM> may have a diameter of about <NUM> to about <NUM>.

<FIG>-5E are side views of five cores 102a-e each having a core distal end 109a-e defining a different core curve 118a-e. <FIG> shows a first core 102a having a distal end 114a defining a core curve 118a that is straight. The first core 102a may be used to support the dilator <NUM> in a substantially straight configuration and/or to impart a stiffness to the dilator <NUM> that may assist in advancing the dilator <NUM> through the blood vessel.

<FIG> are side views of a second, third, fourth and fifth core 102b-e each having core distal ends 114b-e defining different core curves 118b-e. The core curves 118b-e may be planar or in a three-dimensional configuration. The core curves 118b-e may define a radius of curvature, such as, but not limited to, from about <NUM> to about <NUM>. In accordance with embodiments, each core <NUM> may include multiple core curves <NUM> with one or more radii of curvature. It is appreciated that the core curves <NUM> may define any shape suitable for the particular purpose of supporting a dilator <NUM> to track a bend in a blood vessel. The core curves <NUM> may not define a constant radius and may be compound curves of various radii on different planes.

The core <NUM> may be manufactured of any suitable material for the particular purpose, such as, but not limited to, a thermoplastic and metal, such as, but not limited to, stainless steel and nickel titanium alloy. The core curve <NUM> in the cores <NUM> may be formed by any suitable process for a particular material, such as, but not limited to, thermal shape-setting and molding.

In accordance with an embodiment, the core <NUM> may be of the type that is steerable, such as by utilizing active steering mechanisms that are known in the art for steering catheters.

In accordance with an embodiment, one or more radiopaque markers may be coupled to or integrated with the core <NUM>. The radiopaque markers may be positioned near or on the core distal end <NUM> so as to identify a location of the core distal end <NUM> when imaged by x-ray techniques, for example.

The dilator <NUM> is operable to dilate (enlarge) narrow portions of a blood vessel for the purpose of, for example, but not limited to, ensuring that the blood vessel may accept a catheter or sheath therein. In operation, the dilator distal end <NUM> is advanced through the blood vessel. At narrow portions of the blood vessel, the dilator <NUM> comes into urging engagement with and enlarges the diameter of the blood vessel.

At locations where the blood vessel presents a bend, the dilator distal end <NUM> may mistrack, that is, not follow the path of the bend. To assist the dilator distal end <NUM> to track the bend, a core <NUM> is inserted into the dilator lumen <NUM> at the dilator proximal end <NUM> and is advanced to the dilator distal end <NUM> at that location where the dilator <NUM> may tend to mistrack. The core distal end <NUM> is provided with a predetermined curve that is operable to impart a curve to the dilator distal end <NUM> suitable to direct the dilator distal end <NUM> through the bend of the blood vessel. The core <NUM> need not extend beyond the dilator distal end <NUM>. The relative stiffness of the core <NUM>, which is greater than the stiffness of the dilator <NUM>, tends to urge or direct the dilator distal end <NUM> towards and into the bend about the curve imposed by the core distal end <NUM>. Once the dilator distal end <NUM> is beyond the bend, the core curve <NUM> defined by the core distal end <NUM> is placed within the bend. The core <NUM> may be held in place while the dilator <NUM> is advanced over the core <NUM> and through the bend with the core <NUM> guiding the dilator <NUM>.

In many cases, the procedure of enlarging a blood vessel will entail the use of one core <NUM> having a particular core curve <NUM> at the core distal end <NUM>. In other cases, the dilator <NUM> may be advanced to a subsequent bend in the blood vessel that does not have the same bend as the previous bend. The dilator system <NUM> provides that the core <NUM> may be removed from the dilator <NUM> and a subsequent core <NUM> having a different core curve <NUM> may be advanced into and with the dilator <NUM> to the subsequent bend, with the above method repeated to allow the dilator distal end <NUM> to pass through the subsequent bend.

The dilator distal end <NUM> defines a taper of diminishing outer diameter that terminates at a dilator distal tip <NUM>, as shown in <FIG> and <FIG>, where <FIG> shows a cross-sectional view of the dilator <NUM>. The taper allows for, among other things, the dilator distal end <NUM> to have a reduced relative stiffness as compared with the non-tapered portion of the dilator distal end <NUM>. Although the non-tapered portion of the dilator <NUM> has a relative stiffness that is less than that of the core <NUM>, the core curve <NUM> defined by the core distal end <NUM> will be substantially straightened when inserted into the dilator lumen <NUM> within the non-tapered portion of the dilator <NUM> when the dilator <NUM> is supported by a blood vessel, or in an embodiment with a sheath, the dilator <NUM> is supported by the sheath, as will be discussed below.

The lumen of the dilator distal tip <NUM> is also tapered to a smaller diameter than the diameter of the core <NUM>, as shown in <FIG> and <FIG>, such that the core may not exit the dilator distal tip <NUM>, thus preventing the core <NUM> from extending beyond the dilator distal tip <NUM> and possibly injuring the blood vessel. In accordance with an embodiment, the dilator distal tip <NUM> defines a dilator tip lumen comprising a diameter that is less than a diameter of the core <NUM> whereby preventing the core <NUM> from extending beyond the dilator distal tip <NUM>.

When the dilator distal end <NUM> and core <NUM> are advanced into a bend as an assembly, that is, the core <NUM> is within the dilator distal end <NUM>, the dilator distal end <NUM> is no longer supported by the blood vessel and has insufficient stiffness and exterior support to retain the core distal end <NUM> in a substantially straightened configuration and therefore the core distal end <NUM> will impart a curve to the dilator distal end <NUM>. The dilator distal tip <NUM> may then be directed into the bend of the blood vessel. Once the dilator distal tip <NUM> traverses the bend, the core <NUM> may be held in place with the core curve <NUM> of the core <NUM> imparting a curve to the dilator <NUM> that substantially corresponds to the bend of the blood vessel, as the dilator <NUM> is advanced over the core <NUM> and through the bend.

A number of cores <NUM> defining various predetermined core curves <NUM> may be provided operable to impose a curve to the dilator <NUM> suitable to allow the dilator <NUM> to traverse a bend of the blood vessel, in accordance with embodiments. A dilator system <NUM> may comprise one core <NUM> that is operable to be shaped to a particular core curve <NUM> by a user, in accordance with an embodiment. The dilator system <NUM> may comprise one of a number of cores <NUM>, each core <NUM> defining a different core curve <NUM> or core curves <NUM> that a user may select prior to a procedure, in accordance with an embodiment. A dilator system <NUM> may comprise more than one core <NUM> each defining different core curves <NUM> that a user may select during a procedure, in accordance with an embodiment. A variety of cores <NUM> may be offered as a kit to provide multiple options to a user when encountering different anatomical bends within a blood vessel. The number and type of cores <NUM> utilized may depend on the individual patient's anatomy and the path taken within the body. Further, a dilator system <NUM> may comprise a combination of the above described cores <NUM>, in accordance with embodiments.

The dimension of the core curve <NUM> of the core <NUM> may be altered when positioned within a dilator lumen <NUM> where the inherent stiffness of the dilator <NUM> is imposed on the core <NUM>. The dimension of the core curve <NUM> of the core distal end <NUM> outside of the dilator lumen <NUM> as compared with dimension of the core curve <NUM> of the core <NUM> when contained within the dilator lumen <NUM> may be different and a user may compensate for this difference when choosing a core <NUM> having a core curve <NUM> for a particular bend in a blood vessel.

Referring again to <FIG>, the catheter introducer system <NUM> comprising the dilator system <NUM> and a sheath <NUM> as defined in the present invention is discussed below. <FIG> is a side view of the catheter introducer system <NUM> as assembled, in accordance with an embodiment. The sheath <NUM> is operable to be placed within the blood vessel with the assistance of the dilator system <NUM>. After the sheath <NUM> is properly placed within the blood vessel, the dilator system <NUM> is withdrawn from the sheath <NUM>, with the sheath <NUM> remaining to provide a conduit for introducing a catheter into the blood vessel.

The sheath <NUM> is an elongated tubular member having a sheath proximal end <NUM> and a sheath distal end <NUM> opposite from the sheath proximal end <NUM>. The sheath <NUM> further includes a sheath lumen <NUM> extending from the sheath proximal end <NUM> to the sheath distal end <NUM>, therethrough. The sheath lumen <NUM> defines a diameter that is operable to slidingly receive the dilator <NUM> therein and to allow the sheath <NUM> to advance over the dilator <NUM>. In accordance with an embodiment, the sheath <NUM> has a diameter of about <NUM> to about <NUM>, or about <NUM> to about <NUM>.

The dilator <NUM> may be used to dilate (enlarge) narrow portions of the blood vessel in order for a larger diameter sheath <NUM> to advance therethrough. Although the dilator system <NUM> may be used to enlarge a narrowed blood vessel, the dilator system <NUM> may also, or alternatively, be used to assist the advancement of a sheath <NUM> into the blood vessel. The dilator <NUM> may also be used simply as a guide for advancing the sheath <NUM> through the blood vessel without necessarily enlarging the blood vessel. After the dilator <NUM> is advanced within the blood vessel, the sheath distal end <NUM> is advanced over the dilator proximal end <NUM> and advanced on the dilator <NUM> toward the dilator distal end <NUM>, with the dilator <NUM> guiding the sheath <NUM>. In accordance with another example, the sheath distal end <NUM> is advanced over the dilator proximal end <NUM> and advanced over at least a portion of the dilator distal end <NUM> prior to the dilator <NUM> entering the blood vessel. In other words, the sheath <NUM> may be at least partially advanced over the dilator <NUM> prior to use, as shown in <FIG>.

To assist the sheath distal end <NUM> to track the dilator <NUM>, a core <NUM> is advanced into the dilator lumen <NUM> at the dilator proximal end <NUM> and is advanced to the dilator distal end <NUM> at that location where the sheath <NUM> may tend to mistrack. The core distal end <NUM> is provided with a predetermined core curve <NUM> that is operable to impart a curve to the dilator distal end <NUM> and to provide support thereto. The combination of the dilator <NUM> supported by the core <NUM> provides sufficient stiffness at the core curve <NUM> suitable to support and guide the sheath distal end <NUM> through the bend of the blood vessel and to substantially prevent the dilator distal end <NUM> from straightening out under the influence of the sheath <NUM> advancing thereover.

The relative stiffness of the core <NUM> within the dilator distal end <NUM>, which is greater than the stiffness of the sheath <NUM>, tends to urge the sheath distal end <NUM> to track about the curve imposed by the core distal end <NUM> when the sheath <NUM> is advanced over the core curve <NUM>. The stiffness of the core <NUM> is selected so as to be more stiff than the dilator <NUM>, such that the core <NUM> is capable of supporting the dilator distal end <NUM> in a particular curved configuration sufficient to guide either the dilator distal end <NUM> into or through the bend or to guide the sheath distal end <NUM> over the core curve <NUM> and through the bend, or both. The stiffness of the core <NUM> and dilator <NUM> combined is operable so as to be more stiff than the sheath <NUM>, in accordance with an embodiment.

The core curve <NUM> of the core distal end <NUM> is as least partially suppressed, that is, the core distal end <NUM> is at least partially straightened, while moving through the sheath <NUM>. The core curve <NUM> of the core distal end <NUM> is substantially expressed once the core distal end <NUM> is outside of the confines of the sheath <NUM>. The sheath <NUM> must not be so stiff as to be unwilling to track over the imparted curve of the dilator distal end <NUM> as supported by the core <NUM>.

Once the core curve <NUM> of the core distal end <NUM> within the dilator distal end <NUM> is placed within the bend of the blood vessel, the core <NUM> may be held in place while the dilator <NUM> and sheath <NUM> are advanced over the core <NUM> and through the bend with the core <NUM> guiding the dilator distal end <NUM> and sheath distal end <NUM> through the bend.

In another example, once the dilator distal end <NUM> is advanced over the core curve <NUM> of the core <NUM> and beyond the bend, with the core curve <NUM> of the core distal end <NUM> remaining within the bend of the blood vessel, the dilator <NUM> and the core <NUM> are held in place while the sheath <NUM> is advanced over the dilator <NUM> and through the bend.

The sheath <NUM> has a relatively thin wall thickness and comprises a stiffness that is sufficiently low to allow the sheath <NUM> to track though the blood vessel <NUM>. Referring to <FIG>, <FIG> and <FIG>, the sheath <NUM> includes a sheath distal tip <NUM> that tapers to an interface with the dilator <NUM> so as to provide, among other things, a smooth transition between the dilator <NUM> and the sheath <NUM>. Depending on the stiffness of the sheath <NUM>, as the sheath distal end <NUM> traverses over the curve defined by the dilator <NUM> as supported by the core curve <NUM> of the core <NUM>, the sheath distal tip <NUM> may deform from a circular shape to an oval shape, referred to as ovalization. Ovalization may present an enlarged gap between the dilator <NUM> and the sheath <NUM> and may present an edge of the sheath distal end <NUM> that may damage the blood vessel as it is advanced along the curve.

In accordance with an embodiment, the sheath distal tip <NUM> has a stiffness that is greater than the stiffness of the remainder of the sheath distal end <NUM>. The stiffness of the sheath distal tip <NUM> can be an inherent property of the material that the sheath distal tip <NUM> comprises or affected by an element coupled to the sheath distal tip <NUM>, such as, but not limited to, a stiffening band. The sheath distal tip <NUM> defines a length that is sufficiently short so as to not to significantly prevent the sheath distal tip <NUM> from traversing the curve but is sufficiently long so as to support the sheath distal tip <NUM> to prevent significant ovalization. The length of increased stiffness of the sheath distal tip <NUM> may define a length of about <NUM> to about <NUM> in length, in accordance with an embodiment.

<FIG> is an enlarged cross-sectional view of the sheath distal end <NUM> of the embodiment of <FIG>. The sheath distal end <NUM> includes a stiffening band <NUM> operable to impart a stiffness at the sheath distal end <NUM> that is greater than the stiffness proximate to the stiffening band. The stiffening band <NUM> is operable to substantially prevent ovalization of the sheath distal tip <NUM> when the sheath distal tip <NUM> traverses a bend in the blood vessel. Any gap that may form between the dilator <NUM> and the sheath distal end <NUM> when they are in a curved position may be substantially prevented or may be less than about <NUM> when the sheath distal tip <NUM> has a predetermined stiffness that is greater than the stiffness of the remainder of the sheath distal end <NUM>. The sheath distal tip <NUM> and the stiffening band <NUM> may define a length of increased stiffness of about <NUM> to about <NUM> in length, in accordance with an embodiment. The sheath distal tip <NUM> may be tapered to provide a smooth transition between the sheath <NUM> and the dilator <NUM>.

The sheath <NUM> may comprise one or more radiopaque markers <NUM> to assist visualization under x-ray imaging.

<FIG> is a side view of a sheath <NUM> with regions having different stiffness, in accordance with embodiments. The sheath <NUM> may have two or more regions of varied or differing stiffness. In accordance with an embodiment, the sheath proximal end <NUM> may define a first length L1 comprising a higher durometer material or characteristic operable to allow a user to more easily manipulate the sheath <NUM> from the sheath proximal end <NUM> during advancement through the blood vessel. One or more central portions <NUM> of the sheath <NUM> may define a second length L2 comprising a material or material characteristic with a stiffness less than the sheath proximal end <NUM>, and thus being more flexible than the sheath proximal end <NUM>. For example, the durometer at the first length L1 may be about <NUM> to about <NUM> and the durometer at the second length L2 may be about <NUM> to about <NUM> as measured with a Shore D standard. The first length L1 and the second length L2 may be about <NUM> to about <NUM> in length.

The benefit of the central portion <NUM> being more flexible than the sheath proximal end <NUM> allows the central portion <NUM> to more readily take the form of the curve shape provided by the core <NUM> and dilator <NUM>. As previously described, in accordance with embodiments, the sheath distal tip <NUM> at third length L3 comprises a higher durometer or stiffness than the adjacent central portion <NUM> to substantially prevent ovalization. For example, the sheath distal tip <NUM> may have a durometer of, such as, but not limited to, about <NUM> to about <NUM> as measured with a Shore D standard.

<FIG> is a side view of a distal region <NUM> of the catheter introducer system <NUM> substantially the same as the embodiment of <FIG>, in accordance with an embodiment. The dilator <NUM> and sheath <NUM> are assembled such that the dilator distal end <NUM> extends a predetermined distance from the sheath distal end <NUM>, defining an elongated dilator distal region <NUM>. The elongated dilator distal region <NUM> has a length suitable to allow the core distal end <NUM> to impart the curve thereon thereon when inserted therein. Without the elongated dilator distal region <NUM>, the dilator <NUM> may be restricted from defining a curve by the proximity of the relatively stiff sheath <NUM> to the dilator distal end <NUM>. There are varying ranges of lengths of the elongated dilator distal region <NUM> suitable for various embodiments, including a length of about <NUM> to about <NUM>, about <NUM> to about <NUM>, about <NUM> to about <NUM> or about <NUM> to about <NUM>.

The length of the elongated dilator distal region <NUM> can be adjusted, manipulated and held temporarily static by a user during a procedure to position the dilator <NUM> and/or sheath <NUM> in combination with a core <NUM>. As will be discussed below, the dilator <NUM> and the sheath <NUM> may be coupled together to temporarily prevent movement of the dilator <NUM> within the sheath <NUM>, such as when the catheter introducer system <NUM> is positioned in the blood vessel as an assembly.

<FIG> is a cross-sectional view of a distal region <NUM> of a catheter introducer system <NUM>, in accordance with an embodiment of <FIG> and <FIG>. The core distal end <NUM> of the core <NUM> is positioned at least partially within the dilator lumen <NUM> of the dilator <NUM> at the dilator distal end <NUM>. At least a portion of the dilator distal end <NUM> is positioned within the sheath lumen <NUM> of the sheath <NUM> at the sheath distal end <NUM>. The core <NUM> may be advanced within the dilator lumen <NUM> to a substantially distal position, such as in proximity to the dilator distal tip <NUM> but not extending therefrom, as shown in <FIG>, <FIG>.

Referring again to <FIG>, the catheter introducer system <NUM> further comprises a hub <NUM> coupled to the dilator proximal end <NUM>. The hub <NUM> may be used as a handle for guiding the catheter introducer system <NUM>. The hub <NUM> may be operable to couple the dilator <NUM> to one or both of the sheath <NUM> and the core <NUM>. As shown, the sheath <NUM> is distal from the hub <NUM> and may be slidably advanced over the dilator <NUM> towards the dilator distal end <NUM>.

In another embodiment, the sheath proximal end <NUM> may be coupled to the hub <NUM> such that the dilator <NUM> and the sheath <NUM> may be advanced in the blood vessel without relative movement between the dilator <NUM> and the sheath <NUM>. Coupling the sheath <NUM> to the dilator <NUM> facilitates simultaneous advancement of the dilator <NUM> and the sheath <NUM> over a core <NUM> that may be held stationary, for example.

In accordance with an embodiment, the core <NUM> may be coupled to the dilator <NUM> so as to retain the position of the core <NUM> within the dilator <NUM> as the sheath <NUM> is advanced thereover. Coupling may be temporary and can be affected by the use of a threaded, snap or rotary coupler, for example, as is known in the art. Coupling the components at the hub <NUM> can provide more user control and assembly stability while advancing one or more of the components or the entire system through the blood vessel, for example.

In another embodiment, the core <NUM> may be provided with a keyed element for cooperative engagement with a keyed feature on the dilator <NUM> operable to facilitate torsional response or torque when utilized by a user. Such cooperative keyed features may include, such as, but not limited to, a complimentary male/female ridge/groove feature to improve engagement and increase stability between the core <NUM> and dilator <NUM>.

A guidewire <NUM> may be used to initially traverse the blood vessel, in accordance with examples of the dilator guidewire system <NUM> and the catheter introducer guidewire system <NUM>. The guidewire distal end <NUM> of the guidewire <NUM> is advanced through the blood vessel to a desired location. A relatively floppy guidewire distal end <NUM> provides the ability for the guidewire <NUM> to be advanced through complex bends of a blood vessel. The dilator distal end <NUM> of the dilator <NUM> may be advanced over the guidewire proximal end <NUM> and advanced through the blood vessel guided by the guidewire <NUM>. When a core <NUM> is used, the core distal end <NUM> may be advanced onto the guidewire proximal end <NUM> with the core lumen <NUM> receiving the guidewire <NUM> therein. As the core <NUM> is advanced over the guidewire <NUM>, the core <NUM> is also received by and advanced through the dilator lumen <NUM>.

During use, the guidewire <NUM> may be withdrawn and inserted or reinserted into the core lumen <NUM> or the dilator lumen <NUM> if the core <NUM> is not being used. Also the core <NUM> may be withdrawn and inserted or reinserted into the dilator lumen <NUM> during use.

The following is an example of a method of use of the catheter introducer guidewire system <NUM> of <FIG> and <FIG>, by way of example, that will also at least partially apply to the embodiments of methods of use of the dilator system <NUM>, the catheter introducer system <NUM>, and dilator guidewire system <NUM>. <FIG> is a cross-sectional view of a blood vessel <NUM> including a first bend <NUM> and a second bend <NUM>. In this view, the guidewire distal end <NUM> has been advanced through the first bend <NUM> and the second bend <NUM> with the guidewire proximal end <NUM> accessible outside of the blood vessel <NUM>. The dilator distal end <NUM> has been advanced over the guidewire <NUM> beyond the first bend <NUM> guided by the guidewire <NUM>. The dilator <NUM> is able to substantially track on the guidewire <NUM> due to the relative flexibility of the dilator <NUM>. The sheath distal end <NUM> is advanced over the dilator proximal end <NUM> and advanced over the dilator <NUM> such that the sheath distal end <NUM> is before and adjacent to the first bend <NUM>.

<FIG> is a cross-sectional view of the blood vessel <NUM> where a core distal end <NUM> of the core <NUM> has been advanced within the dilator lumen <NUM> and over the guidewire <NUM> such that the core curve <NUM> of the core distal end <NUM> is within the first bend <NUM>. The core distal end <NUM> thus provides support to the dilator distal end <NUM> such that the sheath distal end <NUM> may track over the dilator <NUM> within the first bend <NUM>. The core <NUM> remains within the dilator lumen <NUM> and the dilator distal end <NUM> extends from the sheath distal end <NUM>.

<FIG> is a cross-sectional view of the blood vessel <NUM> where the sheath distal end <NUM> has been advanced over a portion of the dilator distal end <NUM>, over the core curve <NUM> and beyond the first bend <NUM> but before the second bend <NUM>. The second bend <NUM> is too tortuous for the dilator distal end <NUM> to track over the guidewire <NUM> and through the second bend <NUM> without requiring the support of a core <NUM>.

<FIG> is a cross-sectional view of the blood vessel <NUM> where the dilator distal end <NUM> has been advanced a bit further through the blood vessel <NUM> and just before the second bend <NUM>. Either the same core <NUM> or a different core <NUM> having a different core curve <NUM> has been advanced through the dilator <NUM> to the dilator distal end <NUM>. The core distal end <NUM> defines a cure curve <NUM> that assists to curve the dilator distal end <NUM> to direct the dilator distal end <NUM> towards the second bend <NUM>. As the dilator distal end <NUM> is advanced further into and through the second bend <NUM>, the core distal end <NUM> may be advanced with or within the dilator distal end <NUM> to further direct the dilator distal end <NUM> through the second bend <NUM>, until the core curve <NUM> is placed within the second bend <NUM>. The core distal end <NUM> remains in the dilator lumen <NUM> while the dilator distal end <NUM> traverses the second bend <NUM>. If the core <NUM> were to extend from the dilator distal end <NUM>, the core distal end <NUM> may damage the blood vessel <NUM> due to it being a relatively stiff member.

<FIG> is a cross-sectional view of the blood vessel <NUM> where the dilator distal end <NUM> has passed through the second bend <NUM>. Either the same core <NUM> or a different core <NUM> having a different core curve <NUM> has been advanced through the dilator <NUM> to the dilator distal end <NUM> to the second bend <NUM> such that the core curve <NUM> defined by the core distal end <NUM> is within the second bend <NUM>. The core curve <NUM> thus provides support to the dilator distal end <NUM> such that the sheath distal end <NUM> may track over the dilator <NUM> within the second bend <NUM>.

<FIG> is a cross-sectional view of the blood vessel <NUM> where the sheath distal end <NUM> has been advanced over the dilator distal end <NUM> beyond the second bend <NUM>.

<FIG> is a block flow diagram <NUM> of a method of positioning a catheter introducer system in a blood vessel, in accordance with an example. A guidewire is advanced through a blood vessel and placed beyond a bend in the blood vessel <NUM>. A dilator distal end is advanced onto a proximal end of the guidewire and into the blood vessel and positioned beyond the bend guided by the guidewire <NUM>. A sheath is advanced onto a proximal end of a dilator and advanced to adjacent the bend <NUM>. A core defining a core curve is advanced through the lumen of the dilator and over the guidewire placing the core curve in the bend <NUM>. Advancing the sheath and the dilator over the core while retaining the position of the core curve in the bend <NUM>.

<FIG> is a block flow diagram <NUM> of another method of positioning a catheter introducer system in a blood vessel, in accordance with an example. A dilator is advanced through a blood vessel with a proximal end of a dilator advanced to adjacent a bend in the blood vessel <NUM>. A sheath is advanced onto a proximal end of a dilator and advanced to adjacent the dilator distal end <NUM>. A core defining a core curve is advanced through the lumen of the dilator and positioned in the dilator distal end causing the dilator distal end to substantially take the shape of the core curve in the direction of the bend <NUM>. Advancing the dilator over the core and through and beyond the bend <NUM>. Advancing the core curve through the dilator placing the core curve in the bend <NUM>. Advancing the sheath distal end and the dilator over the core and beyond the bend while retaining the position of the core curve in the bend <NUM>.

A dilator was produced by extruding an elongated tubular member comprising <NUM>% low-density polyethylene (LDPE) (Westlake Chemical, Houston, TX) and <NUM>% Santoprene <NUM>-73MED (ExxonMobil Chemical, Houston, TX). The elongated tubular member had an outer diameter of <NUM> and an inner diameter of <NUM>. A molded tapered tip having the same composition was produced and thermally bonded to an end of the elongated tubular member. The approximate length of the tapered tip was <NUM>. The tapered tip had a diameter of approximately <NUM> at a distal end. The total length of the resulting dilator was <NUM>. A hub was bonded to the proximal end of the dilator. A hydrophilic coating was applied to the outer surface of the dilator.

A number of cores were produced from tubing comprising the material Grilamid L25 (EMS-Grivory, Sumter, SC). The tubing had an inner diameter of <NUM> and an outer diameter of <NUM>. The distal end of the cores were held in a curved configuration using tooling and processed in an oven at <NUM> for <NUM>. The core was cooled to room temperature and removed from the tooling, substantially retaining the heat-set shape. One core had a <NUM> radius curve at the distal end. The total length of core was <NUM>.

A sheath was produced having a higher durometer distal tip comprising PEBAX <NUM> SA01 MED (Arkema, King of Prussia, PA) compared with the remainder of the sheath.

The dilator, cores and sheath produced above exhibited the properties as described herein.

Claim 1:
A catheter introducer system (<NUM>) for accessing a blood vessel comprising:
a dilator (<NUM>), the dilator being an elongated tubular member having a dilator proximal end (<NUM>) and a dilator distal end (<NUM>) opposite from the dilator proximal end, the dilator further including a dilator lumen (<NUM>) extending from the dilator proximal end to the dilator distal end therethrough;
a core (<NUM>), the core being an elongated member having a core proximal end (<NUM>) and a core distal end (<NUM>) opposite from the core proximal end, the core (<NUM>) including a core lumen (<NUM>), the core lumen operable to receive a guidewire (<NUM>) and the core (<NUM>) operable to be advanced over the guidewire (<NUM>), the core distal end including a core curve (<NUM>) that defines a predetermined curve, the core being operable for positioning in the dilator lumen (<NUM>) to impart a curvature to the dilator (<NUM>), modify a bending resistance of the dilator, or a combination thereof, the dilator lumen defines a diameter that is operable to slidingly receive the core therein and allow the core to be advanced at least partially within the dilator lumen; and
a sheath (<NUM>), the sheath being an elongated tubular member including a sheath proximal end (<NUM>) and a sheath distal end (<NUM>) opposite from the sheath proximal end, the sheath defining a sheath lumen (<NUM>) extending from the sheath proximal end to the sheath distal end therethrough, the sheath lumen that is operable to slidingly receive the dilator (<NUM>) therein and to allow the sheath to advance over the dilator, wherein the combination of the dilator supported by the core provides sufficient stiffness at the core curve such that the sheath is operable to track over the curvature of the dilator as imparted by the core.