Elongate medical device with continuous reinforcement member

TECHNICAL FIELD

0001The invention relates generally to elongate medical devices. More specifically, the invention relates to an elongate medical device having a continuous reinforcement member.

BACKGROUND

0002Elongated medical devices are commonly used to facilitate navigation through and/or treatment within the anatomy of a patient. A variety of elongate medical devices for intraluminal use, such as catheters, endoscopes, guidewires and the like, have been developed over the past several decades. Because the anatomy of a patient may be very tortuous, it is often desirable to combine a number of performance features in such devices. For example, it is sometimes desirable that the device have a relatively high level of pushability and torqueability, particularly near its proximal end. It is also sometimes desirable that a device be relatively flexible, particularly near its distal end. A number of different elongated medical device structures and assemblies are known, each having certain advantages and disadvantages. However, there is an ongoing need to provide alternative elongated medical device structures, assemblies, and methods.

SUMMARY

0003The invention provides design, material, and manufacturing method alternatives for medical devices, such as catheters, guidewires, and the like. Some embodiments may relate to alternative shaft structures, assemblies, and methods for elongated medical devices, such as catheters or guidewires.

0004Accordingly, some embodiments may include an inner elongate member, a continuous wire disposed about at least a portion of the inner elongate member, and an outer tubular member disposed about at least a portion of the inner elongate member including the continuous wire. In one preferred embodiment, the outer tubular member has a generally constant inside diameter and does not conform to or fill the spaces between turns of the continuous wire. In some embodiments, the continuous wire may include a first section having a first cross-sectional profile, a second section having a second cross-sectional profile different from the first section, and a transition region between the first section and the second section. The first cross-sectional profile may or may not have a cross-sectional area different from the cross-sectional area of the second cross-sectional profile.

0005The above summary of some embodiments is not intended to describe each disclosed embodiment or every implementation of the present invention. The Figures and Detailed Description which follow more particularly exemplify these embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

0006The invention may be more completely understood in consideration of the following detailed description of various embodiments in connection with the accompanying drawings, in which:

0007<figref idref="DRAWINGS">FIG. 1</figref> is a partial side plan view of a medical device in accordance with one example embodiment of the invention shown as a catheter, for example a delivery, guide or diagnostic catheter;

0008<figref idref="DRAWINGS">FIG. 2</figref> is a partial cross-sectional view of a portion of the medical device of <figref idref="DRAWINGS">FIG. 1</figref>;

0009<figref idref="DRAWINGS">FIG. 3</figref> is a partial cross-sectional view of a portion of the shaft of the medical device of <figref idref="DRAWINGS">FIG. 1</figref>, including one example of a distal tip configuration;

0010<figref idref="DRAWINGS">FIG. 4A</figref> is a plan view of a portion of the medical device of <figref idref="DRAWINGS">FIG. 1</figref> with any layers overlaying a reinforcing layer removed, thus exposing a continuous reinforcement member helically wound about a portion of an inner elongate member of the shaft;

0011<figref idref="DRAWINGS">FIG. 4B</figref> is a partial cross-sectional view of the portion of the medical device shown in <figref idref="DRAWINGS">FIG. 4A</figref> and including additional tubular members overlaying the continuous reinforcement member;

0012<figref idref="DRAWINGS">FIG. 5A</figref> is a plan view of a portion of the medical device of <figref idref="DRAWINGS">FIG. 1</figref> with any layers overlaying a reinforcing layer removed, thus exposing an alternative continuous reinforcement member helically wound about a portion of an inner elongate member of the shaft;

0013<figref idref="DRAWINGS">FIG. 5B</figref> is a partial cross-sectional view of the portion of the medical device shown in <figref idref="DRAWINGS">FIG. 5A</figref> and including additional tubular members overlaying the continuous reinforcement member;

0014<figref idref="DRAWINGS">FIG. 6</figref> is a perspective view of a portion of a continuous reinforcement member including a transition region in accordance with the invention as shown in <figref idref="DRAWINGS">FIGS. 4A and 4B</figref>; and

0015<figref idref="DRAWINGS">FIG. 7</figref> is a perspective view of a portion of a continuous reinforcement member including a transition region in accordance with the invention as shown in <figref idref="DRAWINGS">FIGS. 5A and 5B</figref>.

0016While the invention is amenable to various modifications and alternative forms, specifics thereof have been shown by way of example in the drawings and will be described in detail. It should be understood, however, that the intention is not to limit the invention to the particular embodiments described. On the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention.

DETAILED DESCRIPTION

0017For the following defined terms, these definitions shall be applied, unless a different definition is given in the claims or elsewhere in this specification.

0018All numeric values are herein assumed to be modified by the term “about”, whether or not explicitly indicated. The term “about” generally refers to a range of numbers that one of skill in the art would consider equivalent to the recited value (i.e., having the same function or result). In many instances, the term “about” may be indicative as including numbers that are rounded to the nearest significant figure.

0019The recitation of numerical ranges by endpoints includes all numbers within that range (e.g., 1 to 5 includes 1, 1.5, 2, 2.75, 3, 3.80, 4, and 5).

0020As used in this specification and the appended claims, the singular forms “a”, “an”, and “the” include plural referents unless the content clearly dictates otherwise. As used in this specification and the appended claims, the term “or” is generally employed in its sense including “and/or” unless the content clearly dictates otherwise.

0021The following detailed description should be read with reference to the drawings in which similar elements in different drawings are numbered the same. The detailed description and the drawings, which are not necessarily to scale, depict illustrative embodiments and are not intended to limit the scope of the invention. The illustrative embodiments depicted are intended only as exemplary. Selected features of any illustrative embodiment may be incorporated into an additional embodiment unless clearly stated to the contrary.

0022Refer now to <figref idref="DRAWINGS">FIGS. 1 and 2</figref>, which illustrate a medical device <b>10</b> in accordance with one example embodiment. In general, the medical device may be a catheter <b>10</b>, and can include a generally elongate shaft <b>12</b> extending along a central or longitudinal axis x. The axis x extends along the length of the catheter <b>10</b> and necessarily follows the shape and/or curvature of the shaft <b>12</b>. The shaft <b>12</b> can include a proximal portion <b>16</b> having a proximal end <b>18</b>, and a distal portion <b>20</b> having a distal end <b>22</b>. A distal tip <b>28</b> may be disposed at the distal portion <b>20</b>, and a manifold assembly <b>14</b> may be connected at the proximal portion <b>16</b> near proximal end <b>18</b>.

0023As an initial matter, it should be appreciated that while the medical device <b>10</b> is depicted as an intravascular catheter <b>10</b>, and in particular, an intravascular delivery, guide and/or diagnostic catheter <b>10</b>, this is for the purposes of illustration only. Other medical devices embodying aspects of the invention may relate to virtually any medical device including an elongate shaft. For example, other embodiments may relate to medical devices such as a balloon catheter, an atherectomy catheter, a drug delivery catheter, a stent delivery catheter, an endoscope, an introducer sheath, a fluid delivery device, other infusion or aspiration devices, device delivery (i.e., implantation) devices, guidewires and the like. Thus, while the Figures and descriptions below are directed toward a delivery, guide, and/or diagnostic catheter, in other applications the structure and/or sizes in terms of diameter and length may vary widely, depending upon the desired properties of a particular device.

0024Additionally, it should be appreciated that the shaft <b>12</b>, manifold assembly <b>14</b>, and distal tip <b>28</b> can generally include any of a broad variety of structures and/or configurations. It should be understood that the particular configurations and structures shown and described herein are by way of example only, and that a broad variety of alternative structures and/or configurations may be used without departing from the spirit and scope of the invention as claimed.

0025The shaft <b>12</b> can be manufactured, include structure, and be made of materials so as to provide the desired characteristics of the catheter <b>10</b>, depending upon the intended use. For example, the shaft <b>12</b> can be provided and/or manufactured so as to maintain a desired level of flexibility, torqueability and/or other characteristics appropriate for maneuvering the catheter <b>10</b> as desired, for example, through the vasculature of a patient. As such, it should be understood that there is a broad range of possible shaft constructions that may be used, including those particularly discussed herein and others. Some other examples of suitable catheter shaft constructions and materials can be found in U.S. Pat. Nos. 5,569,218; 5,603,705; 5,674,208; 5,680,873; 5,733,248; 5,853,400; 5,860,963; 5,911,715; and 6,866,665, all of which are incorporated herein by reference. Some additional examples of shaft constructions include those disclosed in U.S. patent application Ser. No. 10/238,227 (Publication No. US-2004/0045645), which is also incorporated herein by reference.

0026The shaft <b>12</b> may have a length and an outside diameter appropriate for its desired use, for example, to enable intravascular insertion and navigation. For example, in some embodiments, the shaft <b>12</b> may have a length in the range of about 1 cm to about 300 cm or more, or in some embodiments in the range of about 20 cm to about 250 cm, and an outside diameter in the range of about 1 F to about 20 F, or in some embodiments, in the range of about 1 F to about 10 F. Additionally, although depicted as including a generally round outer diameter and a round cross-sectional shape, it can be appreciated that the shaft <b>12</b> can include other outer diameter and/or cross-sectional shapes or combinations of shapes without departing from the spirit of the invention. For example, the outer diameter and/or cross-sectional shape of the generally tubular shaft <b>12</b> may be oval, rectangular, square, triangular, polygonal, and the like, or combinations thereof, or any other suitable shape, depending upon the desired characteristics.

0027In some embodiments, the catheter <b>10</b> can be a microcatheter including a shaft <b>12</b> that is adapted and/or configured for use within small anatomies of the patient. For example, some embodiments are particularly useful in treating target sites located in tortuous and/or narrow vessels. Some examples of such vessels may include those in the neurovascular system, or in certain sites within the coronary vascular system, or in sites within the peripheral vascular system such as superficial femoral, popliteal, or renal arteries. The target site in some embodiments is a neurovascular site, such as a site in the brain, which is accessible only via a tortuous vascular path, for example, a vascular path containing a plurality of bends or turns which may be greater than about 90° turns, and/or involving vessels which are in the range of about 8 mm or less, and in some cases as small as about 2 to about 3 mm or less, in diameter. As such, in some embodiments, the shaft <b>12</b> can include an outside diameter in the range of approximately 1 F-4 F.

0028However, in other embodiments, the catheter <b>10</b> may be used in other target sites within the anatomy of a patient, in which case the shaft <b>12</b> would be so adapted. For example, the catheter <b>10</b> may be suited for other uses in the digestive system, soft tissues, or any other use including insertion into an organism for medical uses, and the shaft <b>12</b> could be appropriately adapted for such uses. For example, in some embodiments, the catheter <b>10</b> may be used as an introducer sheath, in which case the shaft <b>12</b> may be significantly shorter. The catheter <b>10</b> may also include additional structure and materials adapted for a particular use and/or procedure. For example, in some other embodiments, the shaft <b>12</b> may include additional devices or structures such as inflation or anchoring members, device deployment members, sensors, optical elements, ablation devices, or the like, or any of a broad variety of other structures, depending upon the desired function and characteristics of the catheter <b>10</b>.

0029Referring now to <figref idref="DRAWINGS">FIG. 2</figref>, in at least some embodiments, the shaft <b>12</b> can have a generally tubular construction that includes at least one lumen <b>15</b> extending the length of the shaft <b>12</b> along the longitudinal axis x. This can also be seen with reference to <figref idref="DRAWINGS">FIG. 3</figref>, which is a partial cross-sectional view of the shaft. The lumen <b>15</b> can be defined by an inner surface <b>11</b> of the shaft <b>12</b>, and can have an inner diameter capable of transmitting fluids, or in some cases, receiving another medical device, such as a guidewire, a stent, a coil (such as an embolic coil, or the like), treatment particles (such as embolic particles, or the like), an ablation device, or another catheter, for example, a diagnostic catheter, a balloon catheter, a stent delivery catheter, or the like, or others. In some embodiments, the lumen <b>15</b> can be adapted and/or configured to accommodate another medical device having an outer diameter in the range of about 1 F to about 10 F.

0030In one embodiment, the shaft <b>12</b> includes a generally tubular construction including an inner tubular assembly and/or member <b>24</b>, and an outer tubular assembly and/or member <b>26</b> disposed about at least a portion of the inner tubular member <b>24</b>; however it should be understood that this is by way of example only. The inner tubular member <b>24</b> at least partially defines the inner surface <b>11</b> of the shaft <b>12</b>, and thus defines the lumen <b>15</b>.

0031The inner tubular member <b>24</b> can extend from a point within the distal portion <b>20</b> to a point within the proximal portion <b>16</b> of the shaft <b>12</b>. The length of the inner tubular member <b>24</b> can vary depending upon, for example, the length of the shaft <b>12</b>, the desired characteristics and functions of the inner tubular member <b>24</b>, and other such parameters. In some embodiments, the inner tubular member <b>24</b> can extend substantially the entire length of the shaft <b>12</b>, for example, from a point adjacent the proximal end <b>18</b> to a point adjacent the distal end <b>22</b>. For example, the length of the inner tubular member <b>24</b> can be in the range of about 1-300 centimeters or more, or in some embodiments in the range of about 20 cm-250 cm.

0032Referring to <figref idref="DRAWINGS">FIG. 3</figref>, the inner tubular member <b>24</b> can include a proximal portion <b>33</b> and a distal portion <b>35</b>. The proximal and distal portions <b>33</b>/<b>35</b> can be any proximal or distal sections of the inner tubular member <b>24</b>. However, in some cases the portions <b>33</b>/<b>35</b> can be defined with regard to the relative position of the inner and outer tubular members <b>24</b>/<b>26</b>. For example, the distal portion <b>35</b> can be any portion of the inner tubular member <b>24</b> that extends distally beyond the distal end <b>39</b> of the outer tubular member <b>26</b>, while the proximal portion <b>33</b> can be any portion of the inner tubular member <b>24</b> that is disposed within, or is proximal of a distal end <b>39</b> of the outer tubular member <b>26</b>. In some embodiments inner tubular member <b>24</b> may extend proximal of the proximal end of the outer tubular member <b>26</b> to provide a length of tubing to facilitate attachment of the shaft <b>12</b> with a hub assembly <b>14</b>, or the like. In some embodiments, the distal portion <b>35</b> may be the portion of the inner tubular member <b>24</b> distal of the transition region (<figref idref="DRAWINGS">FIGS. 4A, 5A</figref>) of the continuous wire of a reinforcing layer <b>31</b>, and the proximal portion <b>33</b> may be the portion of the inner tubular member <b>24</b> proximal the transition region. In some embodiments, the distal portion <b>35</b> can have a length in the range of about 0.5 cm or greater, or in the range of about 1 cm or greater, or in the range of about 2 cm or greater, and in some embodiments in the range of about 3 to about 20 cm or in the range of about 1.0 to about 1.5 cm. In some embodiments, the distal portion <b>35</b> can be disposed within, and/or be a part of, or otherwise include a distal tip <b>28</b> construction, some examples of which will be discussed in more detail below.

0033The inner tubular member <b>24</b> may have an inner diameter, for example, defining the lumen <b>15</b>, that is in the range of about 0.01 to about 0.05 inch in size, or in the range of about 0.015 to about 0.03 inch in size, or in the range of about 0.016 to about 0.026 inch in size. As indicated above, however, the lumen <b>15</b> (defined by the inner diameter of the inner tubular member <b>24</b>) can be adapted and/or configured (e.g., sized) to accept other material, fluids, or medical devices, therein, and as such, the size of the lumen <b>15</b> can vary, depending upon the desired characteristics and intended use.

0034Additionally, the inner tubular member <b>24</b> can have an outer diameter that is in the range of about 0.011 inch to about 0.055 inch in size, or in the range of about 0.015 inch to about 0.03 inch in size, or in the range of about 0.019 inch to about 0.029 inch in size. It should be understood, however, that these dimensions are provided by way of example embodiments only and that in other embodiments, the size of the inner and outer diameter of the inner tubular member <b>24</b> can vary greatly from the dimensions given, depending upon the desired characteristics and function of the device.

0035The inner tubular member <b>24</b>, or other portions of the shaft <b>12</b>, may define one or more additional lumens depending upon the desired characteristics and function of the catheter <b>10</b>, and such additional lumens can be shaped, sized, adapted and/or configured the same as or different from lumen <b>15</b>, depending upon the desired characteristic and functions.

0036The inner tubular member <b>24</b> may include and/or be made of any of a broad variety of materials and/or structures. The inner tubular member <b>24</b> may have a single-layer tubular construction or a multi-layer tubular construction, or a combination thereof. For example, the inner tubular member <b>24</b> may be a single tubular member formed by a single layer of material, or in other embodiments, may be formed by a plurality of tubular members and/or a plurality of layers of material that may be the same and/or different, but in combination form the inner tubular member <b>24</b>. In yet other embodiments, some portions of the inner tubular member <b>24</b> can include a single layer construction, while other portions may include a multi-layer construction. Some examples of suitable materials can include, but are not limited to, polymers, metals, metal alloys, or composites or combinations thereof.

0037Some examples of some suitable polymers can include, but are not limited to, polyoxymethylene (POM), polybutylene terephthalate (PBT), polyether block ester, polyether block amide (PEBA), fluorinated ethylene propylene (FEP), polyethylene (PE), polypropylene (PP), polyvinylchloride (PVC), polyurethane, polytetrafluoroethylene (PTFE), polyether-ether ketone (PEEK), polyimide, polyamide, polyphenylene sulfide (PPS), polyphenylene oxide (PPO), polysulfone, nylon, perfluoro(propyl vinyl ether) (PFA), polyether-ester, some adhesive resin, such as modified polyolefin resin, polymer/metal composites, etc., or mixtures, blends or combinations thereof, and may also include or be made up of a lubricous polymer. Some other potentially suitable polymer materials may include those listed below with reference to the outer tubular member <b>26</b>. One example of a suitable polyether block ester is available under the trade name ARNITEL, and one suitable example of a polyether block amide (PEBA) is available under the trade name PEBAX®, from ATOMCHEM POLYMERS, Birdsboro, Pa. In some embodiments, adhesive resins may be used, for example, as tie layers and/or as the material of the structures. One example of a suitable adhesive resin is a modified polyolefin resin available under the trade name ADMER®, from Mitsui Chemicals America, Inc. Additionally, polymer material can in some instances be blended with a liquid crystal polymer (LCP). For example, in some embodiments, the mixture can contain up to about 5% LCP. This has been found in some embodiments to enhance torqueability.

0038Some examples of suitable metals and metal alloys can include stainless steel, such as 304V, 304L, and 316L stainless steel; nickel-titanium alloy such as a superelastic (i.e., pseudoelastic) or linear elastic nitinol; nickel-chromium alloy; nickel-chromium-iron alloy; cobalt alloy; tungsten or tungsten alloys; tantalum or tantalum alloys, gold or gold alloys, MP35-N (having a composition of about 35% Ni, 35% Co, 20% Cr, 9.75% Mo, a maximum 1% Fe, a maximum 1% Ti, a maximum 0.25% C, a maximum 0.15% Mn, and a maximum 0.15% Si); or the like; or other suitable metals, or combinations or alloys thereof. In some embodiments, it is desirable to use metals, or metal alloys that are suitable for metal joining techniques such as welding, soldering, brazing, crimping, friction fitting, adhesive bonding, etc.

0039Referring to <figref idref="DRAWINGS">FIG. 3</figref>, at least a portion of the inner tubular member <b>24</b> can have a multi-layer tubular construction. The example shown includes an inner layer <b>34</b>, an intermediate layer <b>32</b> disposed about the inner layer <b>34</b>, a reinforcing layer <b>31</b> disposed about the intermediate layer <b>32</b>, and an outer layer <b>30</b> disposed about the reinforcing layer <b>31</b> and the intermediate layer <b>32</b>. It should be understood that more or fewer layers can be used, with or without one or more reinforcing layers, depending upon the desired characteristics of the inner tubular member <b>24</b>. Additionally, in other embodiments, the layers could be arranged differently to achieve desired properties. For example, the reinforcing layer <b>31</b> could be disposed at a different radial location, could be disposed entirely within another layer, could be disposed on the outer surface of the inner tubular member <b>24</b>, or, as indicated above, could simply be absent. For example, inner tubular member <b>24</b> may be a single or multi-layer member having a discrete reinforcing layer <b>31</b> such as a wire coil disposed about inner tubular member <b>24</b> along at least a portion of the length of the inner tubular member <b>24</b>. Furthermore, while the layers <b>30</b>, <b>32</b> and <b>34</b> are described, these layers may be provided separately but form a single and/or unitary layer and/or structure. Some or all of the plurality of layers, for example layers <b>30</b>, <b>31</b>, <b>32</b>, <b>34</b>, may be made of any suitable material, for example, those discussed above for use in the inner tubular member <b>24</b>.

0040In some embodiments, the inner layer <b>34</b> may include a lubricious polymer such as HDPE or PTFE, for example, or a copolymer of tetrafluoroethylene with perfluoroalkyl vinyl ether (PFA) (more specifically, perfluoropropyl vinyl ether or perfluoromethyl vinyl ether), or the like. In some particular embodiments, a PTFE tube is used as the inner layer <b>34</b>, which can extend the length of the inner tubular member <b>24</b>.

0041Furthermore, in some embodiments, the intermediate and outer layers <b>32</b>/<b>30</b> may each individually include a flexible polymer, for example a polymer material having a durometer in the range of about 5 D to about 90 D. For example, the intermediate and/or outer layers <b>32</b>/<b>30</b> can include or be made up of one or more tubular segments of a PEBA, a polyether-ester elastomer, or other like material. The durometer of the material used to form the intermediate and/or outer layers <b>32</b>/<b>30</b> may be the same, or may vary from one another, depending upon the characteristics desired. For example, the intermediate layer <b>32</b> may be made of a material having a higher durometer than the material of the outer <b>30</b> layer along at least a portion of the inner tubular member <b>24</b>. In other embodiments, the reverse may be true, and in yet other embodiments, the two layers <b>30</b>/<b>32</b> may include the material having the same or similar flexibility characteristics.

0042In some embodiments, one or both of the layers <b>30</b>/<b>32</b> can be made up of a plurality of tubular segments including materials having different flexibility characteristics to impart varying degrees of flexibility to different longitudinal sections of the intermediate and/or outer layers <b>32</b>/<b>30</b>. For example, in some embodiments, one or both of the layers <b>30</b>/<b>32</b> can include one or more proximal segments (e.g., <b>43</b>/<b>47</b>) and one or more distal segments (e.g., <b>45</b>/<b>45</b>). In some cases, the one or more proximal segments (e.g., <b>43</b>/<b>47</b>) in either one or both layers <b>30</b>/<b>32</b> may include material having a higher durometer than the material included in the distal segment (e.g., <b>45</b>/<b>45</b>) of each or both respective layer <b>30</b>/<b>32</b>. Such a construction may be used, for example, to render a more distal portion of the inner tubular member <b>24</b> more flexible. Such an arrangement can also be helpful, for example, in providing a flexible distal tip construction, or a portion thereof.

0043For example, referring to the embodiment shown in <figref idref="DRAWINGS">FIG. 3</figref>, the intermediate layer <b>32</b> may include a proximal portion <b>43</b> including and/or made of a flexible polymer, such as a PEBA, a polyether-ester elastomer, or other like material, having a durometer in the range of about 40 D to about 70 D. The intermediate layer <b>32</b> may also include a distal portion <b>45</b> including and/or made of a flexible polymer having a durometer in the range of about 15 D to about 35 D. Additionally, the outer layer <b>30</b> may include a proximal portion <b>47</b> including and/or made of such a flexible polymer having a durometer in the range of about 25 D to about 55 D. The outer layer <b>30</b> may also include a distal portion <b>49</b> including and/or made of such a flexible polymer having a durometer in the range of about 15 D to about 35 D.

0044The inner tubular member <b>24</b> can be constructed using any one or a combination of appropriate methods and/or techniques, for example, extrusion, co-extrusion, interrupted layer co-extrusion (ILC), heat bonding techniques, heat shrink techniques, fusing, winding, disposing, adhesive bonding, mechanical bonding, soldering, welding, molding, casting, or the like, or others. In some embodiments, one or more of the layers and/or structures <b>30</b>/<b>31</b>/<b>32</b>/<b>34</b> can be formed separately, and thereafter coupled and/or connected together, while in some embodiments, one or more of the layers and/or structures <b>30</b>/<b>31</b>/<b>32</b>/<b>34</b> can be formed together using suitable techniques.

0045For example, in some embodiments, the layers and/or structures <b>30</b>/<b>31</b>/<b>32</b>/<b>34</b> can be formed separately, such as by extrusion, co-extrusion, interrupted layer co-extrusion (ILC), casting, molding, heat shrink techniques, fusing, winding, or the like, and thereafter coupled or connected together using suitable techniques, such as heat shrink techniques, friction fitting, mechanically fitting, chemically bonding, thermally bonding, welding (e.g., resistance, Rf, or laser welding), soldering, brazing, adhesive bonding, crimping, or the use of a connector member or material, or the like, or combinations thereof, to form the inner tubular member <b>24</b>.

0046In some other embodiments, one or more of the layers and/or structures of the inner tubular member may be formed together at the same or similar times using suitable techniques, such as extrusion, co-extrusion, interrupted layer co-extrusion (ILC), or the like. In some other embodiments, one or more layers, for example the inner layer <b>34</b> and the reinforcing layer <b>31</b>, can be formed and/or provided separately, and thereafter additional layers, for example layers <b>32</b> and <b>30</b>, can be formed onto, over, or with the layers <b>31</b> and <b>34</b> by suitable techniques to form the inner tubular member <b>24</b>.

0047The inner tubular member <b>24</b> may have a uniform stiffness, or may vary in stiffness along its length. For example, a gradual reduction in stiffness from the proximal end to the distal end thereof may be achieved, depending upon the desired characteristics. The gradual reduction in stiffness may be continuous or may be stepped, and may be achieved, for example, by varying the structure, such as the size, thickness, or other physical aspect of one or more of the layers <b>30</b>/<b>31</b>/<b>32</b>/<b>34</b>, or for example, by varying the materials used in one or more of the layers <b>30</b>/<b>31</b>/<b>32</b>/<b>34</b>. Such variability in characteristics and materials can be achieved, for example, by using techniques such as ILC, by fusing together separate extruded tubular segments, or in some cases, varying the characteristics and/or even the very presence or absence of certain structures and/or layers.

0048The one or more reinforcing layer <b>31</b>, if present, can be constructed with any suitable materials and structures to impart the desired characteristics to the inner tubular member <b>24</b>. The reinforcing layer <b>31</b> can include one or more support members that can comprise, for example, a braid, a coil, a filament or wire, or series of such structures, or the like, including material and/or structure adapted to provide the desired characteristics. Examples of suitable materials for constructing the reinforcing layer include polymers, metals, or metal alloys such as those discussed above, or the like, or any of a broad variety of other suitable materials.

0049In some embodiments, the reinforcing layer <b>31</b> can be a coil <b>31</b>. The coil <b>31</b> may be formed of an elongated filament (e.g., wire, ribbon, or the like) having appropriate dimensions and shape to achieve the desired torque, flexibility, and/or other characteristic. For example, the filament used to form the coil <b>31</b> may be circular or non-circular. For instance, the filament may be flattened, ribbon, oval, rectangular, square, triangular, trapezoidal, polygonal, and the like, or any other suitable shape. In describing the filament as being a suitable shape, such as rectangular, square, triangular, or the like, it is the intention not to limit the filament to having a true rectangular, square, triangular, etc., shape. The intention is to include shapes that resemble such shapes. For example, the filament may have rounded corners, nonlinear sides, and/or non-characteristic angles. The coil <b>31</b> can be wrapped in a helical fashion by conventional winding techniques. The pitch of adjacent turns of coil <b>31</b> may be tightly wrapped so that each turn touches the succeeding turn, or the pitch may be set such that coil <b>31</b> is wrapped in an open fashion maintaining a gap between successive turns. The pitch can be constant throughout the length of the coil <b>31</b>, or can vary, depending upon the desired characteristics, for example flexibility. For example, in some embodiments, the coil <b>31</b> can include a distal portion including a relatively open pitch, and a proximal portion having a relatively more closed pitch, such that the coil is more flexible in the distal portion than in the proximal portion. The reinforcing layer <b>31</b> may extend the entire length of the inner tubular member <b>24</b>, or may extend only along a portion of the length thereof. In some embodiments, the reinforcing layer <b>31</b> may extend from a point distal of the proximal end to the distal end of the inner tubular member <b>24</b>. In another embodiment, the reinforcing layer <b>31</b> may extend from the proximal end to a point proximal of the distal end of the inner tubular member <b>24</b>. In still another embodiment, the reinforcing layer <b>31</b> may extend from a point distal of the proximal end to a point proximal of the distal end.

0050One embodiment of the reinforcing layer <b>31</b> may be more clearly described herein. Referring to <figref idref="DRAWINGS">FIG. 4A</figref>, reinforcing layer <b>31</b> may be a continuous wire <b>75</b>. A continuous wire is a single filament that extends from one end of the wire to the opposite end of the wire without splicing, welding, brazing or other means of joining two wires together. A continuous wire <b>75</b> may overcome challenges associated with initiating and/or terminating a reinforcement member at a location other than the proximal region or distal region of a catheter construction. Using two or more discrete coil sections to achieve dissimilar flexibilities throughout the length of a shaft may be disadvantageous. Terminating and initiating adjacent coil sections at an intermediate location may encourage kinking of the shaft, may allow separation of a reinforcing layer from an inner/outer member, or may create an uneven transition through the shaft, for example.

0051Continuous wire <b>75</b> may be helically wound about at least a portion of inner member <b>24</b>. Continuous wire <b>75</b> may be helically wound at a constant pitch about a portion of inner member <b>24</b>, or the pitch of continuous wire <b>75</b> may be varied step-wise or gradually along a portion of inner member <b>24</b>. For instance, continuous wire <b>75</b> may be tightly wound (i.e., successive turns are placed closer together) along a proximal portion <b>80</b> of inner member <b>24</b> and continuous wire <b>75</b> may be more loosely wound (i.e., successive turns are spaced farther apart) along a distal portion <b>82</b> of inner member <b>24</b>. Continuous wire <b>75</b> may be wound from the proximal end of inner member <b>24</b> to the distal end of inner member <b>24</b> or any portion thereof. For example, continuous wire <b>75</b> may be wound from a point distal of the proximal end of inner member <b>24</b> to the distal end of inner member <b>24</b>, continuous wire <b>75</b> may be wound from the proximal end of inner member <b>24</b> to a point proximal of the distal end of inner member <b>24</b>, or continuous wire <b>75</b> may be wound from a point distal of the proximal end of inner member <b>24</b> to a point proximal of the distal end of inner member <b>24</b>.

0052As shown in <figref idref="DRAWINGS">FIG. 4A</figref>, inner member <b>24</b> may have a lumen <b>15</b> extending therethrough. However, in some embodiments, such as a guidewire, inner member <b>24</b> may be a core wire not including a lumen, such as lumen <b>15</b>. Lumen <b>15</b>, if present, may be sized to provide access to the distal end of the elongate shaft through lumen <b>15</b>, for example, to accommodate advancing an additional medical device therethrough.

0053Continuous wire <b>75</b> may include a first portion <b>77</b>, a second portion <b>79</b>, and a transition region <b>78</b> located between first portion <b>77</b> and second portion <b>79</b>. Although continuous wire <b>75</b> is shown with one transition region <b>78</b>, one or more additional transition regions may be included in continuous wire <b>75</b>. Transition region <b>78</b> may provide a transition between first portion <b>77</b> and second portion <b>79</b>. Transition region <b>78</b> may include a tapered transition, a step-wise transition, or other such transition between first portion <b>77</b> and second portion <b>79</b>. For example, transition region <b>78</b> may alternatively be a region of rotation of continuous wire <b>75</b>. Continuous wire <b>75</b> having different transverse dimensions may be rotated, for instance by 45, 90, or 180 degrees, through transition region <b>78</b> in order to vary the flexibility of continuous wire <b>75</b>. For example, continuous wire <b>75</b> may be flattened, rectangular, or otherwise have different transverse dimensions, wherein one of two shorter sides is in contact with the inner member <b>24</b> in the proximal portion <b>80</b> of inner member <b>24</b>. In transition region <b>78</b>, continuous wire <b>75</b> may be rotated 90 degrees such that one of two longer sides is in contact with the inner member <b>24</b> in the distal portion <b>82</b> of inner member <b>24</b>. By rotating the continuous wire <b>75</b>, the radial extent of the continuous wire <b>75</b> from the longitudinal axis x of the elongate shaft is changed between the proximal portion <b>80</b> and the distal portion <b>82</b> of inner member <b>24</b>. The radial extent of the continuous wire <b>75</b> is intended to mean the distance from the longitudinal axis x of the elongate shaft to the outermost point of the helically wound continuous wire <b>75</b> in a radial direction. As shown in <figref idref="DRAWINGS">FIG. 4A</figref>, the radial extent R₁of the first portion <b>77</b> of continuous wire <b>75</b> is greater than the radial extent R₂of the second portion <b>79</b> of continuous wire <b>75</b>. Continuous wires <b>75</b> of other shapes having different transverse dimensions may be rotated in a similar manner in order to achieve two or more regions of different flexibility. By reducing the radial extent of the continuous wire <b>75</b> in the distal portion <b>82</b> of the inner member <b>24</b>, the flexibility of the distal portion <b>82</b> is increased. Thus, the second portion <b>79</b> of continuous wire <b>75</b> having a reduced radial extent may provide a distal tip portion of the shaft with a higher degree of flexibility and a lower profile than a portion of the shaft proximal of the transition region <b>78</b>.

0054As can be better seen in <figref idref="DRAWINGS">FIG. 4B</figref>, a first portion <b>77</b> of continuous wire <b>75</b> may have a first cross-sectional profile having a first cross-sectional area, and a second portion <b>79</b> of continuous wire <b>75</b> may have a second cross-sectional profile having a second cross-sectional area. The first cross-sectional profile may be constant throughout the first portion <b>77</b> of continuous wire <b>75</b> and the second cross-sectional profile may be constant throughout the second portion <b>79</b> of continuous wire <b>75</b>. Transition region <b>78</b> (<figref idref="DRAWINGS">FIG. 4A</figref>) may provide transition between the cross-sectional profile of the first portion <b>77</b> and the cross-sectional profile of the second portion <b>79</b> of continuous wire <b>75</b>. The first cross-sectional profile may be dissimilar from the second cross-sectional profile. For example, the first portion <b>77</b> may have a circular cross-sectional profile and the second portion <b>79</b> may have a non-circular cross-sectional profile, such as a ribbon, oval, flattened, square, or rectangular profile. The cross-sectional area of the circular cross-sectional profile may or may not be different from the cross-sectional area of the non-circular cross-sectional profile. In other embodiments, the first portion <b>77</b> may have a circular or non-circular cross-sectional profile having a first cross-sectional area and the second portion <b>79</b> may have a circular or noncircular cross-sectional profile having a second cross-sectional area different from the first cross-sectional area. For example, continuous wire <b>75</b> may include a proximal portion <b>77</b> having a first circular cross-sectional profile and a distal portion <b>79</b> having a second circular cross-sectional profile. The cross-sectional area of the first circular cross-sectional profile may be different from the cross-sectional area of the second circular cross-sectional profile. For instance, the first cross-sectional area may be greater than or less than the second cross-sectional area. Differences in the cross-sectional profile and/or cross-sectional area of the proximal portion relative to the cross-sectional profile and/or cross-sectional area of the distal portion <b>79</b> may enhance the flexibility characteristics of the elongate shaft. For example, the distal portion <b>79</b> having a dissimilar profile may provide the elongate shaft with a very flexible, lower profile distal tip portion.

0055Proximal portion <b>77</b> of continuous wire <b>75</b> may be helically wound around a length of inner member <b>24</b>. For instance, helically wound proximal portion <b>77</b> may extend a majority of the length of inner member <b>24</b>. In some embodiments, helically wound proximal portion <b>77</b> may extend a length of about 20 cm or more, about 50 cm or more, about 75 cm or more, or about 100 cm or more, for example. Distal portion <b>79</b> of continuous wire <b>75</b> may be helically wound around a length of inner member <b>24</b>. For instance, helically wound distal portion <b>79</b> may extend proximally along inner member <b>24</b> from the distal end of inner member <b>24</b>, or helically wound distal portion <b>79</b> may extend distally from the proximal end of distal tip portion <b>28</b> to a point within distal tip portion <b>28</b>. In some embodiments, distal portion <b>79</b> may extend for a length of about 5 cm or less, about 3 cm or less, about 2 cm or less, about 1.5 cm or less, or about 1 cm or less along a distal portion of inner member <b>24</b>, for example. Distal portion <b>79</b> may be positioned within a distal tip portion <b>28</b> of the shaft.

0056As mentioned previously, the radial extent R₁of the proximal portion <b>77</b> of the helically wound continuous wire <b>75</b> along proximal portion <b>80</b> of inner member <b>24</b> may be greater than the radial extent R₂of the distal portion <b>79</b> of the helically wound continuous wire <b>75</b> along distal portion <b>82</b> of inner member <b>24</b>. Therefore, the portion of the shaft including the distal portion <b>79</b> of continuous wire <b>75</b> may have a lower profile and/or a higher degree of flexibility than the portion of the shaft including the proximal portion <b>77</b>. Additionally or alternatively, a change in the flexibility of the shaft may be achieved by varying the pitch of the continuous wire <b>75</b> between the proximal portion <b>77</b> and the distal portion <b>79</b>.

0057As shown in <figref idref="DRAWINGS">FIG. 4B</figref>, an outer tubular member <b>26</b> may be disposed about at least a portion of inner member <b>24</b> including the continuous wire <b>75</b>. Outer tubular member <b>26</b> may be disposed about a proximal portion of inner member <b>24</b> including the continuous wire <b>75</b>. For reasons of clarity, an additional layer(s) overlaying continuous wire <b>75</b> and disposed within the lumen of outer tubular member <b>26</b> as shown in <figref idref="DRAWINGS">FIG. 3</figref> is not illustrated in <figref idref="DRAWINGS">FIG. 4B</figref>. However, some embodiments may include at least one layer of inner member <b>24</b> or an additional layer interposed between continuous wire <b>75</b> and outer tubular member <b>26</b>, or along a portion thereof. In some embodiments, no additional layer may be located between continuous wire <b>75</b> and outer tubular member <b>26</b>.

0058Distal end <b>39</b> of outer tubular member <b>26</b> may be located proximate transition region <b>78</b>. For example, distal end <b>39</b> may be positioned about 2 cm or less, about 1 cm or less, or about 0.5 cm or less from transition region <b>78</b> of continuous wire <b>75</b>. Outer tubular member <b>26</b> may extend proximally from a point proximate transition region <b>78</b> to the proximal region of the elongate shaft. In some embodiments, outer tubular member <b>26</b> may extend over the entire proximal portion <b>77</b> of helically wound continuous wire <b>75</b>. In some embodiments, outer tubular member <b>26</b> may extend from the proximal end of the elongate shaft to the transition region <b>78</b>. However, outer tubular member <b>26</b> may extend distal of the transition region in some embodiments and may extend to the distal end of the elongate shaft in some embodiments. Outer tubular member <b>26</b> may include a plurality of slots or apertures <b>44</b> cut through the wall of outer tubular member <b>26</b> to provide a degree of flexibility to the elongate shaft. In a preferred embodiment, the outer tubular member has a generally constant diameter over a substantial portion of its length. Thus, the inside surface does not conform to or fill the spaces between successive turns of the reinforcing layer. Outer tubular member <b>26</b> will be further described hereinafter.

0059A distal tip portion <b>28</b> may be disposed about a distal portion of inner member <b>24</b> including the continuous wire <b>75</b>. Proximal end <b>29</b> of distal tip <b>28</b> may be located proximate transition region <b>78</b> such that proximal end <b>29</b> of distal tip <b>28</b> may abut or mate with distal end <b>39</b> of outer tubular member <b>26</b>. For example, proximal end <b>29</b> may be positioned about 2 cm or less, about 1 cm or less, or about 0.5 cm or less from transition region <b>78</b> of continuous wire <b>75</b>. In some embodiments, distal tip <b>28</b> may extend over and surround a distal portion of outer tubular member <b>26</b>. Distal tip <b>28</b> may extend to the distal end of the elongate shaft to provide a flexible atraumatic tip to the elongate shaft.

0060Another embodiment of reinforcing layer <b>31</b> comprising a continuous wire <b>175</b> disposed about at least a portion of inner member <b>24</b> is shown in <figref idref="DRAWINGS">FIGS. 5A and 5B</figref>. Continuous wire <b>175</b> may be similar to continuous wire <b>75</b> shown in <figref idref="DRAWINGS">FIGS. 4A and 4B</figref>. Continuous wire <b>175</b> may include a proximal portion <b>177</b> having first cross-sectional profile and a distal portion <b>179</b> having a second cross-sectional profile different from the first cross-sectional profile. A transition region <b>178</b> may be located between the proximal portion <b>177</b> and the distal portion <b>179</b> providing a transition between the two portions of continuous wire <b>175</b>. The first cross-sectional profile may be a flattened wire (i.e., ribbon) having a first radial extent R₁and the second cross-sectional profile may be a flattened wire (i.e., ribbon) having a second radial extent R₂less than the first radial extent R₁. The radial extent of the continuous wire <b>175</b> is intended to mean the distance from the longitudinal axis x of the elongate shaft to the outermost point of the helically wound continuous wire <b>175</b> in a radial direction. The distal portion <b>179</b> having a reduced radial extent may provide the distal tip region of the shaft with a higher degree of flexibility and a lower profile segment than more proximal segments.

0061As shown in <figref idref="DRAWINGS">FIG. 5B</figref>, an outer tubular member <b>26</b> may be disposed about a proximal portion of inner member <b>24</b> including the continuous wire <b>175</b>. As mentioned above, an additional layer(s) may or may not be interposed between outer tubular member <b>26</b> and continuous wire <b>175</b>. Distal end <b>39</b> of outer tubular member <b>26</b> may be located proximate transition region <b>178</b>. For example, distal end <b>39</b> may be positioned about 2 cm or less, about 1 cm or less, or about 0.5 cm or less from transition region <b>178</b> of continuous wire <b>175</b>. In some embodiments, outer tubular member <b>26</b> may extend over transition region <b>178</b> and/or distal portion <b>179</b> of continuous wire <b>175</b>. Outer tubular member <b>26</b> may include a plurality of slots or apertures <b>44</b> cut through the wall of outer tubular member <b>26</b> to provide a degree of flexibility to the elongate shaft. Outer tubular member <b>26</b> will be further described hereinafter.

0062A distal tip portion <b>28</b> may be disposed about a distal portion of inner tubular member <b>24</b> including the continuous wire <b>175</b>. Proximal end <b>29</b> of distal tip <b>28</b> may be located proximate transition region <b>178</b> such that proximal end <b>29</b> of distal tip <b>28</b> may abut or adjoin distal end <b>39</b> of outer tubular member <b>26</b>. For example, proximal end <b>29</b> may be positioned about 2 cm or less, about 1 cm or less, or about 0.5 cm or less from transition region <b>178</b> of continuous wire <b>175</b>. Distal tip <b>28</b> may extend to the distal end of the elongate shaft to provide a flexible atraumatic tip to the elongate shaft.

0063<figref idref="DRAWINGS">FIG. 6</figref> shows a portion of continuous wire <b>75</b> including a transition region <b>78</b> located between a proximal portion <b>77</b> and a distal portion <b>79</b> of continuous wire <b>75</b> as disclosed regarding <figref idref="DRAWINGS">FIGS. 4A and 4B</figref>. Proximal portion <b>77</b> may have a circular cross-sectional profile <b>72</b> having a diameter D₁and distal portion <b>79</b> may have a non-circular cross-sectional profile <b>73</b>, which may be a profile having a width W₁and a height H₁. Width W₁may be greater than height H₁. For example, width W₁may be two times, four times, or ten times greater than height H₁. Additionally, diameter D₁may be greater than H₁such that when continuous wire <b>75</b> is helically wound about inner member <b>24</b>, the radial extent R₁of the proximal portion <b>77</b> is greater than the radial extent R₂of the distal portion <b>79</b>. In some embodiments, the cross-sectional area of the cross-sectional profile <b>72</b> may be equivalent to the cross-sectional area of the cross-sectional profile <b>73</b>. In alternative embodiments, the cross-sectional area of profile <b>72</b> may be greater than or less than the cross-sectional area of profile <b>73</b>.

0064Distal portion <b>79</b> may be formed in continuous wire <b>75</b> by grinding, cold working, drawing, pressing, shaping, chemical etching, electro-polishing, or otherwise deforming/altering distal portion <b>79</b> of continuous wire <b>75</b> into the second cross-sectional profile <b>73</b>. In deforming/altering distal portion <b>79</b>, transition region <b>78</b> is formed, providing a transition between proximal portion <b>77</b> and distal portion <b>79</b>. Distal portion <b>79</b> may have a specified length such that when distal portion <b>79</b> is helically wound around inner member <b>24</b>, distal portion <b>79</b> extends along inner member <b>24</b> a length of about 0.5 cm to about 5 cm, or about 1 cm to about 3 cm or about 1 cm to about 1.5 cm, for example. Thus, the chosen length of distal portion <b>79</b> may be a function of the outer diameter of inner member <b>24</b>, the pitch of helically wound continuous wire <b>75</b>, and/or the number of windings of continuous wire <b>75</b>, for example.

0065Proximal portion <b>77</b> may have a specified length such that when proximal portion <b>77</b> is helically wound around inner member <b>24</b>, proximal portion <b>77</b> extends a majority of the length of the inner member <b>24</b>. In some embodiments, proximal portion <b>77</b> may have a length such that helically wound proximal portion <b>77</b> extends about 20 cm or more, about 50 cm or more, or about 100 cm or more, for example. Helically wound proximal portion <b>77</b> may be sized to extend within about 10 cm or less, about 5 cm or less, about 2 cm or less, or about 1 cm or less of the proximal end of inner member <b>24</b>, for example. Thus, the chosen length of proximal portion <b>77</b> may be a function of the outer diameter of inner member <b>24</b>, the pitch of helically wound continuous wire <b>75</b>, and/or the number of windings of continuous wire <b>75</b>, for example.

0066<figref idref="DRAWINGS">FIG. 7</figref> shows a transition region <b>178</b> located between a proximal portion <b>177</b> and a distal portion <b>179</b> of continuous wire <b>175</b> as disclosed regarding <figref idref="DRAWINGS">FIGS. 5A and 5B</figref>. Proximal portion <b>177</b> may have a non-circular cross-sectional profile <b>172</b>, which may be a ribbon profile having a width W₂and a height H₂. Width W₂and height H₂may be different, thus cross-sectional profile <b>172</b> may be substantially rectangular (e.g., flat wire), or width W₂and height H₂may be substantially equivalent, thus cross-sectional profile <b>172</b> may be substantially square (e.g., flat wire). In describing the cross-sectional profile as square or rectangular, profiles are intended to resemble those of squares and rectangles. For example, the cross-sectional profiles may include rounded corners, nonlinear sides, and/or non-characteristic angles, thus not creating a true square or rectangular profile. Distal portion <b>179</b> may have a non-circular cross-sectional profile <b>173</b>, which may be a ribbon profile having a width W₃and a height H₃. Width W₃may be greater than height H₃, such that distal portion <b>179</b> of continuous wire <b>175</b> is a flattened ribbon portion. In some embodiments, width W₃may be greater than width W₂and/or height H₂may be greater than height H₃. For example, width W₃may be two times, four times, or ten times greater than width W₂and/or height H₂may be two times, four times, or ten times greater than height H₃. H₂may be greater than H₃such that the radial extent R₁of the proximal portion <b>177</b> is greater than the radial extent R₂of the distal portion <b>179</b> when the continuous wire <b>175</b> is helically wound around inner member <b>24</b>. In some embodiments, the cross-sectional area of the first cross-sectional profile <b>172</b> may be equivalent to the cross-sectional area of the second cross-sectional profile <b>173</b>. In alternative embodiments, the first cross-sectional area of profile <b>172</b> may be greater than or less than the second cross-sectional area of profile <b>173</b>.

0067Similar to continuous wire <b>75</b>, distal portion <b>179</b> may be formed in continuous wire <b>175</b> by grinding, cold working, drawing, pressing, shaping, chemical etching, electro-polishing, or otherwise deforming/altering distal portion <b>179</b> of continuous wire <b>175</b> into the second cross-sectional profile <b>173</b>. In deforming/altering distal portion <b>179</b>, transition region <b>178</b> is formed providing a transition between proximal portion <b>177</b> and distal portion <b>179</b>. Distal portion <b>179</b> may have a specified length such that when distal portion <b>179</b> is helically wound around inner member <b>24</b>, distal portion <b>179</b> extends along inner member <b>24</b> a length of about 0.5 cm to about 5 cm, or about 1 cm to about 3 cm or about 1 cm to about 1.5 cm, for example. Thus, the chosen length of distal portion <b>179</b> may be a function of the outer diameter of inner member <b>24</b>, the pitch of helically wound continuous wire <b>175</b>, and/or the number of windings of continuous wire <b>175</b>, for example.

0068Proximal portion <b>177</b> may have a specified length such that when proximal portion <b>177</b> is helically wound around inner member <b>24</b>, proximal portion <b>177</b> extends a majority of the length of the inner member <b>24</b>. In some embodiments, proximal portion <b>177</b> may have a length such that helically wound proximal portion <b>177</b> extends about 20 cm or more, about 50 cm or more, or about 100 cm or more, for example. Helically wound proximal portion <b>177</b> may be sized to extend within about 10 cm or less, about 5 cm or less, about 2 cm or less, or about 1 cm or less of the proximal end of inner member <b>24</b>, for example. Thus, the chosen length of proximal portion <b>177</b> may be a function of the outer diameter of inner member <b>24</b>, the pitch of helically wound continuous wire <b>175</b>, and/or the number of windings of continuous wire <b>175</b>, for example.

0069Referring again to <figref idref="DRAWINGS">FIGS. 1-3</figref>, the outer member <b>26</b> can also be a generally tubular member including a proximal region <b>36</b> having a proximal end <b>37</b> and a distal region <b>38</b> having a distal end <b>39</b>. The outer tubular member <b>26</b> can be disposed about at least a portion of the inner tubular member <b>24</b> at a location along the length of the shaft <b>12</b> between proximal end <b>18</b> and distal end <b>22</b>. In the embodiment shown, the outer member <b>26</b> is disposed about the inner tubular member <b>24</b> along the proximal portion <b>16</b> of the shaft <b>12</b>, but it should be understood that other locations are possible.

0070The length of the outer tubular member <b>26</b> can also vary, depending upon, for example, the length of the shaft <b>12</b>, the desired characteristics and functions of the catheter <b>10</b>, and other such parameters. In some embodiments, the outer member <b>26</b> has a length that allows it to be disposed over the majority of the length of the inner tubular member <b>24</b>, and in some embodiments, is disposed about all but up to the distal most 15 cm or less of the inner tubular member <b>24</b> and/or all but the proximal most 15 cm or less of the inner tubular member <b>24</b>. In some embodiments, the distal end of the outer tubular member <b>26</b> is disposed about 3.0 cm or less, 2.0 cm or less, 1.5 cm or less or 1.0 cm or less proximal the distal end of the inner member <b>24</b>. In some embodiments, the length of the outer tubular member <b>26</b> can be in the range of about 1 cm to about 299 cm or more, or in some embodiments in the range of about 19 cm-249 cm.

0071The tubular outer member <b>26</b> defines a lumen <b>40</b> that can be adapted and/or configured to house or surround a portion of the inner tubular member <b>24</b>. In some embodiments, the lumen <b>40</b> can have an inner diameter that is in the range of about 0.015 inch to about 0.06 inch in size, and in some embodiments, in the range of about 0.02 inch to about 0.035 inch in size. In some embodiments, the outer tubular member <b>26</b> can have an outer diameter that is in the range of about 0.016 inch to about 0.07 inch in size, or in the range of about 0.02 inch to about 0.04 inch in size. It should be understood however, that these, and other dimensions provided herein, are by way of example only.

0072In at least some embodiments, the outer tubular member <b>26</b> can have an inner diameter that is greater than the outer diameter of the inner tubular member <b>24</b>. As such, the outer tubular member <b>26</b> can be disposed about the inner tubular member <b>24</b> (i.e., a portion of the inner tubular member <b>24</b> is disposed within the lumen <b>40</b> of the outer member) such that a space or gap <b>42</b> is defined between at least a portion of the outer surface <b>25</b> of the inner tubular member <b>24</b> and the inner surface <b>27</b> of the outer member <b>26</b>. In some embodiments, the space or gap <b>42</b> can be in the range of about 0.0002 to about 0.004 inch in size, and in some embodiments, in the range of about 0.0005 to about 0.003 inch in size. Again, it should be understood that these dimensions are provided by way of example only. In some embodiments, space or gap <b>42</b> may be substantially filled by reinforcing layer <b>31</b>. For example, continuous wire <b>75</b> may be disposed in gap <b>42</b> between inner member <b>24</b> and outer tubular member <b>26</b>. However, in some embodiments the outer tubular member <b>26</b> is substantially contiguous with the inner tubular member <b>24</b> such that no gap or space is formed between the inner tubular member <b>24</b> and the outer tubular member <b>26</b>.

0073Typically, relatively large portions of the gap or space <b>42</b> remain open or unfilled by any other structure of the catheter <b>10</b> along a substantial portion of the length thereof, and in some cases along a substantial portion of the length of the outer tubular member <b>26</b>. For example, in some embodiments, 50% or more, 75% or more, 90% or more, or 95% or more of the gap or space <b>42</b> remains open and/or unfilled by any other structure of the catheter.

0074In some embodiments, attachment points along the length of the outer tubular member <b>26</b> may be used to attach to the inner tubular member <b>24</b>. As a result, the gap or space <b>42</b> may be partially or totally filled at these attachment points, and as such, divided up into what may be considered multiple and/or a plurality of separate gaps or spaces that are unfilled. Additionally, other structures, such as coils, bands, braids, polymer layers, or the like, may fill portions of the gap or space <b>42</b>. Even so, such multiples of the gap or space <b>42</b>, or the so defined multiple gaps or spaces <b>42</b> may still collectively extend along a substantial portion of the length of the outer tubular member <b>26</b> and remain overall substantially unfilled over the majority of the length thereof, for example, in percentages of the total length as given above. As such, the outer tubular member <b>26</b> can act to reinforce or impart desired properties, such as torsional and lateral rigidity, to the catheter shaft <b>12</b>, and may allow at least the portion of the inner tubular member <b>24</b> surrounded by the gap or space <b>42</b> to be separate from, and in some cases bend and/or move laterally within, the lumen <b>40</b>. Some examples of structure, methods, and techniques of coupling the tubular outer member <b>26</b> to the inner tubular member <b>24</b> will be discussed in more detail below.

0075The outer tubular member <b>26</b> can be adapted and/or configured to have a desired level of stiffness, torqueability, flexibility, and/or other characteristics. Those of skill in the art and others will recognize that the dimensions, structure, and materials of the outer tubular member <b>26</b> are dictated primarily by the desired characteristics, and the function of the final catheter <b>10</b>, and that any of a broad range of the dimensions, structure, and materials can be used.

0076The desired stiffness, torqueability, lateral flexibility, bendability or other such characteristics of the outer member <b>26</b> can be imparted or enhanced by the structure of the outer tubular member <b>26</b>. For example, the outer tubular member <b>26</b> may include a thin wall tubular structure, including one or a plurality of apertures <b>44</b>, such as grooves, cuts, slits, slots, or the like, formed in a portion of, or along the entire length of, the tubular outer member <b>26</b>. Such structure may be desirable because it may allow outer tubular member <b>26</b>, or portions thereof, to have a desired level of lateral flexibility as well as have the ability to transmit torque and pushing forces from the proximal region <b>36</b> to the distal region <b>38</b>. In some embodiments, slots or apertures <b>44</b> may extend substantially transverse to the longitudinal axis x of the outer tubular member <b>26</b>. The apertures <b>44</b> can be formed in essentially any known way. For example, apertures <b>44</b> can be formed by methods such as micro-machining, saw-cutting, laser cutting, grinding, milling, casting, molding, chemically etching or treating, or other known methods, and the like. In some such embodiments, the structure of the outer tubular member <b>26</b> is formed by cutting and/or removing portions of the tube to form apertures <b>44</b>.

0077In some embodiments, the apertures <b>44</b> can completely penetrate the outer tubular member <b>26</b> such that there is fluid communication between the lumen <b>40</b> and the exterior of the outer tubular member <b>26</b> through the apertures <b>44</b>. In some embodiments, the apertures <b>44</b> may only partially extend into the structure of the outer tubular member <b>26</b>, either on the interior or exterior surface thereof. Some other embodiments may include combinations of both complete and partial apertures <b>44</b> through the structure of the outer tubular member <b>26</b>. The shape and size of the apertures <b>44</b> can vary, for example, to achieve the desired characteristics. For example, the shape of apertures <b>44</b> can vary to include essentially any appropriate shape, such as square, round, rectangular, pill-shaped, oval, polygonal, elongate, irregular, or the like, and may include rounded or squared edges, and can be variable in length and width, and the like.

0078Additionally, the spacing, arrangement, and/or orientation of the apertures <b>44</b>, or in some embodiments, associated spines or beams that may be formed, can be varied to achieve the desired characteristics. For example, the number or density of the apertures <b>44</b> along the length of the outer tubular member <b>26</b> may be constant or may vary, depending upon the desired characteristics. For example, the number or proximity of apertures <b>44</b> to one another near one end of the outer member <b>26</b> may be high, while the number or proximity of slots to one another near the other end of the outer tubular member <b>26</b> may be relatively low and/or non existent, or vice versa. For example, in the embodiment shown in <figref idref="DRAWINGS">FIGS. 1, 2</figref>, and <b>3</b>, the distal region <b>38</b> of the outer tubular member <b>26</b> includes a plurality of apertures <b>44</b> having a relatively high density relative to the plurality of apertures <b>44</b> located in the proximal region <b>36</b>. As such, the distal region <b>38</b> can have a greater degree of lateral flexibility relative to the proximal region <b>36</b>. The density of the apertures <b>44</b> can vary gradually or in a stepwise fashion over the length of the outer tubular member. And as suggested above, certain portions of the outer tubular member <b>26</b> may not include any such apertures.

0079In some embodiments, the distal about 10% to about 50% of the total length of the outer tubular member <b>26</b> can include apertures <b>44</b> defined therein at a relatively high density, while the proximal about 50% to about 90% of the total length of the outer tubular member <b>26</b> include apertures <b>44</b> defined therein at a relatively low density, and/or is free of such apertures <b>44</b>. For example, in some embodiments, the distal region <b>38</b> having a length in the range of about 30 cm to about 70 cm includes apertures <b>44</b> defined therein at a relatively high density to provide for relatively greater flexibility, while the remaining length in the proximal region <b>36</b> of the outer tubular member <b>26</b> include apertures <b>44</b> defined therein at a relatively low density, and/or is free of such apertures <b>44</b>, to provide for relatively greater stiffness. It should be understood however, that these, and other dimensions provided herein, are by way of example embodiments only, and that in other embodiments, the disposition of apertures <b>44</b> can vary greatly from the dimensions given, depending upon the desired characteristics and function of the device.

0080As suggested above, the apertures <b>44</b> may be formed such that one or more spines or beams <b>50</b> are formed in the tubular outer member <b>26</b>. Such spines or beams <b>50</b> (<figref idref="DRAWINGS">FIG. 1</figref>) could include portions of the tubular member <b>26</b> that remain after the apertures <b>44</b> are formed in the body of the outer tubular member <b>26</b>. Such spines or beams <b>50</b> may act to maintain a relatively high degree of torsional stiffness, while maintaining a desired level of lateral flexibility. In some embodiments, some adjacent apertures <b>44</b> can be formed such that they include portions that overlap with each other about the circumference of the tube. In other embodiments, some adjacent apertures <b>44</b> can be disposed such that they do not necessarily overlap with each other, but are disposed in a pattern that provides the desired degree of lateral flexibility. Additionally, the apertures <b>44</b> can be arranged along the length of, or about the circumference of, the outer tubular member <b>26</b> to achieve desired properties. For example, the apertures <b>44</b> can be arranged in a symmetrical pattern, such as being disposed essentially equally on opposite sides about the circumference of the outer tubular member <b>26</b>, or equally spaced along the length of the outer tubular member, or can be arranged in an increasing or decreasing density pattern, or can be arranged in a non-symmetric or irregular pattern.

0081Collectively, these Figures and this Description illustrate that changes in the arrangement, number, and configuration of slots may vary without departing from the scope of the invention. Some additional examples of shaft constructions and/or arrangements of cuts or slots formed in a tubular body are disclosed in U.S. Pat. No. 6,428,489 and in published U.S. patent application Ser. Nos. 09/746,738 (Pub. No. US 2002/0013540), and 10/400,750 (Pub. No. US-2004/0193140), all of which are incorporated herein by reference. Also, some additional examples of shaft constructions and/or arrangements of cuts or slots formed in a tubular body for use in a medical device are disclosed in U.S. patent application Ser. Nos. 10/375,493, and 10/400,750, which are also incorporated herein by reference.

0082In addition to, in combination with, or as an alternative to the structure of the outer member <b>26</b>, the materials selected for outer tubular member <b>26</b> may also be chosen so that may have the desired characteristics. The outer tubular member <b>26</b> may be formed of any materials suitable for use, dependent upon the desired properties of the catheter <b>10</b>. For example, outer tubular member <b>26</b> may be formed of materials having a desired modulus of elasticity, given the structure used. Some examples of suitable materials include metals, metal alloys, polymers, or the like, or combinations or mixtures thereof.

0083Some examples of suitable metals and metal alloys include stainless steel, such as 304V, 304L, and 316L stainless steel; alloys including nickel-titanium alloy such as linear elastic or superelastic (i.e., pseudoelastic) nitinol; nickel-chromium alloy; nickel-chromium-iron alloy; cobalt alloy; tungsten or tungsten alloys; MP35-N (having a composition of about 35% Ni, 35% Co, 20% Cr, 9.75% Mo, a maximum 1% Fe, a maximum 1% Ti, a maximum 0.25% C, a maximum 0.15% Mn, and a maximum 0.15% Si); hastelloy; monel 400; inconel 625; or the like; or other suitable material, or combinations or alloys thereof In some embodiments, it is desirable to use metals, or metal alloys that are suitable for metal joining techniques such as welding, soldering, brazing, crimping, friction fitting, adhesive bonding, etc.

0084Some examples of suitable polymeric materials may include, but are not limited to: poly(L-lactide) (PLLA), poly(D,L-lactide) (PLA), polyglycolide (PGA), poly(L-lactide-co-D,L-lactide) (PLLA/PLA), poly(L-lactide-co-glycolide) (PLLA/PGA), poly(D, L-lactide-co-glycolide) (PLA/PGA), poly(glycolide-co-trimethylene carbonate) (PGA/PTMC), polyethylene oxide (PEO), polydioxanone (PDS), polycaprolactone (PCL), polyhydroxylbutyrate (PHBT), poly(phosphazene), polyD,L-lactide-co-caprolactone) (PLA/PCL), poly(glycolide-co-caprolactone) (PGA/PCL), polyanhydrides (PAN), poly(ortho esters), poly(phoshate ester), poly(amino acid), poly(hydroxy butyrate), polyacrylate, polyacrylamid, poly(hydroxyethyl methacrylate), polyurethane, polysiloxane and their copolymers, or mixtures or combinations thereof. Some other potentially suitable polymer materials may include those listed above with reference to the inner tubular member <b>24</b>.

0085As indicated above, some embodiments may include linear-elastic or super-elastic nitinol in various structures and/or components of the shaft <b>12</b> (e.g., outer tubular member <b>26</b>, inner tubular member <b>24</b>, etc.). The word nitinol was coined by a group of researchers at the United States Naval Ordinance Laboratory (NOL) who were the first to observe the shape memory behavior of this material. The word nitinol is an acronym including the chemical symbol for nickel (Ni), the chemical symbol for titanium (Ti), and an acronym identifying the Naval Ordinance Laboratory (NOL). In some embodiments, nitinol alloys can include in the range of about 45 to about 60 weight percent nickel, with the remainder being essentially titanium. It should be understood, however, that in other embodiment, the range of weight percent nickel and titanium, and or other trace elements may vary from these ranges. Within the family of commercially available nitinol alloys, are categories designated as “superelastic” (i.e., pseudoelastic) and “linear elastic” which, although similar in chemistry, exhibits distinct and useful mechanical properties.

0086In some embodiments, a superelastic alloy, for example a superelastic nitinol, can be used to achieve desired properties. Such alloys typically display a substantial “superelastic plateau” or “flag region” in its stress/strain curve. Such alloys can be desirable in some embodiments because a suitable superelastic alloy will provide an outer member <b>26</b> that exhibits some enhanced ability, relative to some other non-superelastic materials, of substantially recovering its shape without significant plastic deformation upon the application and release of stress, for example, during placement of the catheter in the body.

0087In some other embodiments, a linear elastic alloy, for example a linear elastic nitinol, can be used to achieve desired properties. For example, in some embodiments, certain linear elastic nitinol alloys can be generated by the application of cold work, directional stress, and/or heat treatment, such that the material fabricated does not display a substantial “superelastic plateau” or “flag region” in its stress/strain curve. Instead, in such embodiments, as recoverable strain increases, the stress continues to increase in a somewhat linear relationship until plastic deformation begins. In some embodiments, the linear elastic nickel-titanium alloy is an alloy that does not show any martensite/austenite phase changes that are detectable by DSC and DMTA analysis over a large temperature range. For example, in some embodiments, there are no martensite/austenite phase changes detectable by DSC and DMTA analysis in the range of about −60° C. to about 120° C. The mechanical bending properties of such material are therefore generally inert to the effect of temperature over a broad range of temperature. In some particular embodiments, the mechanical properties of the alloy at ambient or room temperature are substantially the same as the mechanical properties at body temperature. In some embodiments, the use of the linear elastic nickel-titanium alloy allows the outer member to exhibit superior “pushability” around tortuous anatomy. One example of a suitable nickel-titanium alloy exhibiting at least some linear elastic properties is FHP-NT alloy commercially available from Furukawa Techno Material Co. of Kanagawa, Japan. Additionally, some examples of suitable nickel-titanium alloy exhibiting at least some linear elastic properties include those disclosed in U.S. Pat. Nos. 5,238,004 and 6,508,803, which are incorporated herein by reference.

0088In some embodiments, the outer tubular member <b>26</b>, or other portions of the shaft <b>12</b>, can be formed of a shape-memory material, for example a shape memory alloy such as a shape memory nitinol. In such embodiments, the shape memory effect can be used in the deployment or use of the catheter, for example in causing the outer tubular member <b>26</b>, or other portions of the shaft <b>12</b>, to move from a first insertion configuration to a second use configuration, or, for example, for the outer tubular member <b>26</b> to “remember” its desired shape after deformation to another shape.

0089For example, in some embodiments, the outer tubular member <b>26</b> can include or be made of a shape memory alloy that is martensite at room temperature, and has a final austenite transition temperature (A_f) somewhere in the temperature range between room temperature and body temperature. For example, in some such embodiments, the shape memory alloy has a final austenite transition temperature in the range of about 25° C. and about 37° C. (e.g., about body temperature). In some such embodiments, it may be desirable that the final austenite transition temperature be at least slightly below body temperature, to ensure final transition at body temperature. This feature allows the outer member <b>26</b> to be inserted into the body of a patient in a martensitic state, and assume its preformed, austenitic shape when exposed to the higher body temperature within the anatomy, or at the target site. In this embodiment, deployment of the outer tubular member <b>26</b> can be achieved by a shape memory effect; as the material warms, it undergoes a transition from martensite to austenite form, causing transformation of the outer tubular member <b>26</b> from the first configuration to the second configuration.

0090In other example embodiments, the outer tubular member <b>26</b> can include or be made of a shape-memory alloy that could have a transition temperature M_d(wherein M_d=highest temperature to strain-induced martensite) that is in the range of body temperature (e.g., about 37° C.) or greater, below which the alloy retains sufficient stress-induced martensitic property to allow placement of the outer tubular member <b>26</b> at or above its final austenite transition temperature (A_f). In other words, this allows the catheter, including the outer tubular member <b>26</b> in its preformed austenitic state, to be inserted and navigated in the anatomy, where the outer tubular member <b>26</b> may be exposed to stress that may promote portions thereof to undergo stress-induced martensitic (SIM) transformation. Thereafter, the outer tubular member <b>26</b> may recover its preformed, austenitic shape when released from the stress of navigation, at a temperature that may be substantially above the final austenite transition temperature without significant plastic, or otherwise permanent deformation. Additionally, in some such embodiments, the outer tubular member <b>26</b> can be constrained, for example, in a delivery device, such as a guide catheter, in a stress-induced martensitic (SIM) state, and recover its preformed, austenitic shape when released from the constraints of the catheter, at a temperature that may be substantially above the final austenite transition temperature without significant plastic, or otherwise permanent deformation. In these embodiments, the final austenite temperature may be quite low, e.g., 4° C. or lower, or it may be up to room temperature or higher.

0091In yet other embodiments, the outer tubular member <b>26</b> can include or be made of a shape memory alloy that is martensite at body temperature, and has a final austenite transition temperature (A_f) somewhere in the temperature range above body temperature. This feature allows the catheter including the outer tubular member <b>26</b> to be navigated in a martensitic state, and maintain a martensitic state until exposed to a temperature higher than body temperature. The outer tubular member <b>26</b> can then be heated to the necessary temperature above body temperature to make the transformation from martensite to austenite using an external heating means or mechanism. Such mechanisms may include the injection of heated fluid through the catheter or other device, the use of electrical or other energy to heat the outer tubular member <b>26</b>, or other such techniques. In some such embodiments, the shape-memory alloy has a final austenite transition temperature in the range of about 37° C. to about 45° C. It may be desirable that the final austenite transition temperature be at least slightly above body temperature, to ensure there is not final transition at body temperature. Some examples of Nitinol cylindrical tubes having desired transition temperatures, as noted above, can be prepared according to known methods.

0092Referring to <figref idref="DRAWINGS">FIG. 3</figref>, the outer tubular member <b>26</b> may be connected to the inner tubular member <b>24</b> using any of a broad variety of suitable techniques, some examples of which may include adhesive bonding, friction fitting, mechanically fitting, crimping, chemically bonding, thermally bonding, welding (e.g., resistance, Rf, or laser welding), soldering, brazing, or the use of a connector member or material, or the like, or combinations thereof. As discussed above, in at least some embodiments, the outer tubular member <b>26</b> can be disposed about the inner tubular member <b>24</b> (i.e., a portion of the inner tubular member <b>24</b> is disposed within the lumen <b>40</b> of the outer member) such that a space or gap <b>42</b> is defined between at least a portion of the outer surface <b>25</b> of the inner tubular member <b>24</b> and the inner surface <b>27</b> of the outer tubular member <b>26</b>. In some embodiments, there may be no space between outer tubular member <b>26</b> and inner member <b>24</b>, or space or gap <b>42</b> may be substantially filled with another member, such as reinforcement member <b>31</b>.

0093In <figref idref="DRAWINGS">FIG. 3</figref>, the outer tubular member <b>26</b> is attached to the inner tubular member <b>24</b> at one or more proximal attachment point <b>53</b>, one or more distal attachment point <b>59</b>, and one or more intermediate attachment point <b>61</b>. In some embodiments, such attachment points can be achieved, for example, using an adhesive material, for example, a cyanoacrylate, or other suitable type of adhesive. In at least some embodiments, only a relatively small portion of the outer member <b>26</b> is connected to the inner tubular member <b>24</b> at the attachment points. For example, the length of each individual bond joint, especially at the intermediate bond joints, may only be about 5 cm or less, or 3 cm or less, or 1 cm or less, or 0.5 cm or less. In some embodiments, where appropriate, the bonds extend under or within about five or fewer of the apertures <b>44</b>, or three or even two or fewer of the apertures <b>44</b>, along the length of the outer tubular member. Some embodiments may include a plurality of intermediate attachment point <b>61</b> spaced apart along the length of the shaft <b>12</b>. In some embodiments, the distance between attachment points along the length of the shaft <b>12</b> may be in the range of about 5 cm and about 40 cm, or in the range of about 7 cm to about 30 cm, and may vary or be constant along the length of the shaft <b>12</b>. For example, the spacing between attachment points may be closer together near the distal end of the shaft, and may be farther apart near the distal portion of the shaft <b>12</b>.

0094As indicated above, the distal portion <b>20</b> of the shaft <b>12</b> can include a distal tip <b>28</b>. The distal tip <b>28</b> can be a structure, assembly, construction and/or arrangement adapted and/or configured to provide characteristics such as shapability, flexibility, steerability, atraumatic characteristics, or the like, for example, to the distal portion and/or distal end of the shaft <b>12</b>. A broad variety of distal tip constructions, configurations, and/or structures are generally known for use on medical devices, such as catheters, and may be used. In some embodiments, the distal tip <b>28</b> may be disposed at the distal portion <b>20</b> of the shaft <b>12</b>, and may extend distally beyond other portions of the shaft <b>12</b>. In some embodiments, distal tip <b>28</b> may extend proximally from the distal end <b>22</b> of shaft <b>12</b> to transition region <b>78</b> of continuous wire <b>75</b>. Thus, distal tip <b>28</b> may extend over distal portion <b>79</b> of continuous wire <b>75</b>. The low profile of distal portion <b>79</b> provides distal tip <b>28</b> with a higher degree of flexibility and lower profile than portions of elongate shaft <b>12</b> proximal of transition region <b>78</b> of continuous wire <b>75</b>.

0095In some embodiments, the distal tip <b>28</b> is simply one or more portions of the shaft <b>12</b>, and/or components thereof (e.g. the inner and/or outer tubular members <b>24</b>/<b>26</b>) that include materials and/or structures to provide the desired characteristics. For example, in the embodiment shown in <figref idref="DRAWINGS">FIG. 3</figref>, the distal tip <b>28</b> can include and/or extend about the distal portion <b>20</b> of shaft <b>12</b> including the inner tubular member <b>24</b>. In this regard, the distal tip <b>28</b> may include the distal portion <b>20</b> of shaft <b>12</b> including the inner tubular member <b>24</b>, and may additionally include one or more additional layers and/or structures <b>52</b> disposed about the distal portion <b>20</b> of shaft <b>12</b> including the inner tubular member <b>24</b>. In other embodiments, however, the distal tip <b>28</b> may include structure and/or material that may be considered to be separate and distinct from other portions of the shaft, but that is connected to the distal portion of the shaft <b>12</b> to form the distal tip.

0096In <figref idref="DRAWINGS">FIG. 3</figref>, the layer <b>52</b> is disposed about the distal portion <b>20</b> of shaft <b>12</b> including the inner tubular member <b>24</b>. The layers <b>30</b>, <b>32</b>, and <b>34</b> of the inner tubular member <b>24</b> may include distal portions, for example <b>45</b> and <b>49</b>, that include materials having desirable flexibility characteristics, for example, as discussed above. Additionally, the layer <b>52</b> may be made of or include any suitable material or structure, and may be disposed by any suitable process, the materials, structures, and processes varying with the particular application and characteristics desired. For example, in some embodiments, the one or more additional layers and/or structures may include a layer of polymer or other such material, or structures such as coils, braids, ribbons, wires, bands, or the like.

0097In this embodiment, the outer layer <b>52</b> may include and/or be made of a polymer material disposed about the distal portion <b>35</b> of the inner tubular member <b>24</b>. For example, the outer layer <b>52</b> may include a flexible polymer material having a durometer in the range of about 5 D to about 35 D. Some examples of suitable polymers may include those discussed above with regard to the layers of the inner tubular member <b>24</b>, with one example being a PEBA material, or the like. As can be appreciated, in some embodiments, the coil layer <b>31</b>, such as distal portion <b>79</b> of continuous wire <b>75</b>, extends partially into the distal tip <b>28</b>, but ends and is spaced proximally from the distal end <b>22</b>. In other embodiments, however, the coil <b>31</b>, or other such reinforcing structure, or the like, may extend to the distal end <b>22</b>. Additionally, it should be understood that one or more additional layers and/or constructions may be used in the distal tip <b>28</b>.

0098The outer layer <b>52</b> may be sized appropriately so as to maintain a generally constant diameter in the transition between the outer tubular member <b>26</b> and the outer layer <b>52</b>, and may include a portion <b>65</b> that abuts and/or overlaps the distal end <b>39</b> of the outer tubular member <b>26</b> to provide a smooth transition. Additionally, as in the embodiment shown, the outer tubular member <b>26</b> may include a recessed, or reduced diameter portion at the distal end <b>39</b> thereof, and the outer layer <b>52</b> may overlap and/or mate with the recessed portion to provide for a smooth transition. In other embodiments, however, a tapered or step down transition may be provided.

0099The outer layer <b>52</b> can be constructed and/or disposed using any appropriate technique, for example, by extrusion, co-extrusion, interrupted layer co-extrusion (ILC), coating, heat shrink techniques, heat bonding, thermally bonding, casting, molding, fusing one or several segments of an outer layer material end-to-end, adhesive bonding, chemically bonding, crimping, friction fitting, mechanically fitting, or the like, or combinations thereof.

0100A lubricious, a hydrophilic, a protective, or other type of coating may be applied over portions of or the entire shaft <b>12</b>. Hydrophobic coatings such as fluoropolymers provide a dry lubricity which improves catheter handling and device exchanges. Lubricious coatings can aid in insertion and steerability. Suitable lubricious polymers are well known in the art and may include silicone and the like, hydrophilic polymers such as polyarylene oxides, polyvinylpyrolidones, polyvinylalcohols, hydroxy alkyl cellulosics, algins, saccharides, caprolactones, and the like, and mixtures and combinations thereof. Hydrophilic polymers may be blended among themselves or with formulated amounts of water insoluble compounds (including some polymers) to yield coatings with suitable lubricity, bonding, and solubility. Some other examples of such coatings and materials and methods used to create such coatings can be found in U.S. Pat. Nos. 6,139,510 and 5,772,609, which are incorporated herein by reference.

0101It should also be understood that in some embodiments, a degree of MRI compatibility can be imparted into shaft <b>12</b>. For example, to enhance compatibility with Magnetic Resonance Imaging (MRI) machines, it may be desirable to construct portions of the outer tubular member <b>26</b>, portions of the inner tubular member <b>24</b>, or other portions of the shaft <b>12</b>, in a manner, or use materials, that would impart a degree of MRI compatibility. For example, the lengths of relatively conductive structures within the shaft <b>12</b> may be limited to lengths that would not generate undue heat due to resonance waves created in such structures when under the influence of an MRI field generated by an MRI machine. Alternatively or additionally, portions, or the entire shaft <b>12</b> may be made of a material that does not substantially distort the image and create substantial artifacts (artifacts are gaps in the image). Certain ferromagnetic materials, for example, may not be suitable because they may create artifacts in an MRI image. Additionally, all or portions of the shaft <b>12</b>, may also be made of, impregnated with, plated or clad with, or otherwise include a material and/or structure that the MRI machine can image. Some materials that exhibit these characteristics include, for example, tungsten, Elgiloy, MP35N, nitinol, and the like, and others. Additionally, some structures including or made of such materials, such as marker bands, marker coils, rings, impregnated polymer sections, or the like, may be added to or included in the shaft <b>12</b>. Those skilled in the art will recognize that these materials can vary widely without departing from the spirit of the invention.

0102Additionally, all or portions of the shaft <b>12</b>, or components or layers thereof, may be made of, impregnated with, plated or clad with, or otherwise include a radiopaque material and/or structure to facilitate radiographic visualization. Radiopaque materials are understood to be materials capable of producing a relatively bright image on a fluoroscopy screen or another imaging technique during a medical procedure. This relatively bright image may aid the user of catheter <b>10</b> in determining its location. Some examples of radiopaque materials can include, but are not limited to, gold, platinum, palladium, tantalum, tungsten alloy, polymer material loaded with radiopaque filler, and the like.

0103For example, with reference to <figref idref="DRAWINGS">FIGS. 1-3</figref>, the inner tubular member <b>24</b> can include one or more radiopaque marker member <b>55</b> disposed in the distal portion <b>35</b> between the intermediate and outer layers <b>32</b>/<b>30</b>, or at other positions and/or locations. Additionally, the outer tubular member <b>26</b> can include one or more marker members disposed thereon. In the embodiment shown, the marker member <b>55</b> is a tubular marker band, but it should be understood that other marker structures and arrangements, such as marker coils, rings, impregnated polymer sections, or the like, may be used, and may be disposed at locations along and/or within the shaft <b>12</b>. Furthermore, the elongate shaft <b>12</b>, or portions thereof, may be curved and/or shaped as desired, or be adapted and/or configured to be curved and/or shaped as desired, depending on the particular application.

0104Those skilled in the art will recognize that the present invention may be manifested in a variety of forms other than the specific embodiments described and contemplated herein. Accordingly, departure in form and detail may be made without departing from the scope and spirit of the present invention as described in the appended claims.