Patent Description:
Guidewires are known for delivering catheters to many vascular locations in the body. Access to remote and tortuous vasculature is facilitated by a combination of mechanical properties such as flexibility, pushability and torqueability.

Coronary catheters can track over simple coronary guidewires to coronary vasculature and can be used to position treatment devices dilatation balloons and stents. Some coronary guidewires are also able to measure blood pressure in the segment of the coronary vasculature. Upon measurement of blood pressure, a treatment diagnosis can be used to guide the treatment to be performed. For example, a measurement such as fractional flow reserve (FFR) can be used to determine which patients should be treated with a balloon, a stent or other approach.

While pressure measuring guidewires have been described and even marketed for many years, such devices can be improved.

<CIT> describes a guidewire system for treating a patient may include a sensor assembly for detecting a physiological characteristic of a patient and a hypotube sized for insertion into vasculature of the patient and having an integrated sensor mount formed therein for predictably locating the sensor during assembly. The hypotube may also have a wall structure and a lumen, and the sensor mount may be formed within the wall structure of the hypotube and may include a first mechanical stop configured to limit movement of the sensor assembly in at least a first dimension and a second mechanical stop configured to limit movement of the sensor assembly in at least a second dimension. A sensor housing may be disposed about the sensor mount and may have a window formed therein to provide fluid communication between the sensor assembly and an environment outside the hypotube.

A need exists for more robust pressure guidewires. Pressure guidewires are very thin and yet contain sophisticated devices in complex assemblies. The assembly process and requirements of use can lead to fracture and other failure modes. Thus, such guidewires should be configured with robust connections between different functional parts. Such guidewires should be made with junctions that preserve delicate structures that measure pressure. Such guidewires should be configured to enhance kink resistance.

A device according to the invention is disclosed in claim <NUM>. Also disclosed are the following examples. In one example, a pressure guidewire is provided that includes a shaft tube assembly, a hypotube, and a tip pressure sensor. The shaft tube assembly can have a proximal section, a middle section, and a sensor housing section. The proximal section can have a first tubular body. The first tubular body can have a proximal end, a distal end, a proximal outside surface and a proximal inside surface. The proximal inside surface can enclose a proximal portion of a central lumen. The proximal outside surface can comprise or form an outer surface of the pressure guidewire. The middle section can have a proximal end, a middle section outside surface, and a middle section inside surface. The middle section inside surface can be disposed about a space within the pressure guidewire. The proximal end of the middle section can be separate from the distal end of the proximal section. The proximal end of the middle section can be coupled to the distal end of the proximal section. The sensor housing section can extend distally relative to the middle section. The hypotube can have a proximal end portion and a distal end portion. The hypotube can extend through the space about which the middle section inside surface is disposed. The proximal end portion of the hypotube can be coupled with the distal end of the proximal section. The distal end portion of the hypotube can be coupled to the sensor housing. The tip pressure sensor can be positioned in the sensor housing section.

In another example, a pressure guidewire is provided that has a proximal end and a distal end. The pressure guidewire has a proximal section, a sensor housing section, and an intermediate section. The proximal section extends from the proximal end of the pressure guidewire to a distal end of the proximal section. The sensor housing section is disposed adjacent to the distal end of the pressure guidewire. The intermediate section disposed between the proximal section and the sensor housing section. The intermediate section has a proximal end separate from the proximal section. The proximal end can be coupled to the distal end of the proximal section. The pressure guidewire has a tubular body and a pressure sensor. The tubular body has a proximal end portion and a distal end portion. The tubular body is positioned within the intermediate section. The pressure sensor is positioned in the sensor housing section. The pressure sensor has a signal conductor disposed proximally of the sensor housing through the tubular body.

The pressure guidewire provides more flexibility in the intermediate section than the proximal section. In one example, a wall thickness of the pressure guidewire is less in the intermediate section than in the proximal section. In one example, the pressure guidewire provides a stepped lumen profile. In one example, the wall thickness of the pressure guidewire is less in the intermediate section than in the proximal section and the pressure guidewire provides a stepped lumen profile.

A thinner wall section can allow a tubular body, e.g., a hypotube, to be disposed in the intermediate portion of the assembly. The tubular body, e.g., the hypotube, can have a smaller outside diameter that provides more flexibility than the larger outside diameter and thicker wall of the proximal section.

In some examples, the sensor that makes pressure measurements includes a micro-electromechanical systems (MEMS) devices which are very small and also very delicate. The assembly of the MEMS device in the pressure guidewires must be carefully done to reduce potential for damage to the MEMS device and/or to sources of measurement error that can arise due to damaging the MEMS structure.

In some cases, the guidewire assembly includes a tip assembly that includes an atraumatic tip, a core wire and a coil structure. The atraumatic tip can be coupled to the core wire by a suitable technique, such as by welding. The core wire can be provided with a heat shield or heat sink to contain heat added to the structure to maintain the heat affected zone away from nearby corewire smaller sections.

In another example, a guidewire assembly is provided that includes a proximal section and a distal section. The distal section extends distally of the proximal section. The distal section has an exterior metal body portion, a sensor assembly, and a metal ring member. The sensor assembly has a sensor body and a signal conductor coupled with the sensor body. The sensor assembly is disposed through the exterior body portion. The metal ring member is disposed between the exterior metal body portion and the signal conductor of the sensor assembly. The exterior metal body is joined to the metal ring member providing two metal layers around the sensor assembly.

In another example, a method of forming a guidewire assembly is provided. A sensor body is coupled to a metal ring member. The metal ring member is disposed within an exterior metal body. A portion of an exterior surface of the metal ring member and a portion of an interior surface of the exterior metal body are joined.

In another example, a guidewire assembly is provided that includes a proximal section, a distal portion, and a junction. The proximal section has a proximal end and a distal end. The distal portion has a proximal end coupled with the distal end of the proximal section. A detector is disposed at or adjacent to a distal end of the distal portion. The junction includes the distal end of the proximal section and the proximal end of the distal portion. The junction has an enhanced ductility zone. The enhanced ductility zone includes a length of the distal portion including the proximal end thereof, a length of the proximal section including the distal end thereof, or a length of the distal portion including the proximal end thereof and a length of the proximal section including the distal end thereof.

In another example, , a method is provided for forming a pressure guidewire. In the method, a proximal body is provided. The proximal body has a first tubular wall that has a first wall thickness and a lumen of a first diameter. A distal body is provided that has a second tubular wall that has a second wall thickness and a lumen of a second diameter. The first diameter is smaller than the second diameter. The first wall thickness is greater than the second wall thickness. A distal end of the proximal body is coupled to a proximal end of the distal body to provide a continuous assembly from proximal of the distal end of the proximal catheter body to distal of the proximal end of the distal catheter body. Heat is applied to the continuous assembly after coupling, e.g., after welding, to enhance the ductility of at least a portion of the continuous assembly disposed at a location from proximal of the distal end of the proximal body to distal of the proximal end of the distal body.

In another example, a pressure guidewire is provided that has a shaft tube assembly, a pressure sensor disposed in a distal portion of the shaft tube assembly, and a tip assembly. The pressure sensor is coupled with a signal conduit to convey pressure signals to a processor. The tip assembly includes a core wire and an atraumatic tip. The core wire has a proximal end coupled to a distal portion of the shaft tube assembly and an elongate tapered body having a lesser diameter toward a distal end thereof. The atraumatic tip portion has a proximal end coupled with a distal end of the core wire and a rounded distal end. The proximal end is configured to restrain heat gain at the distal end of the core wire to prevent a change in material properties in the distal end of the core wire.

In another example, a method of forming a pressure sensing guidewire is provided. A shaft tube assembly is provided that has a distal portion with a pressure sensor disposed therein and a distal end. A proximal end of a core wire is coupled with the distal end of the shaft tube assembly. The wire has an elongate tapered body having a smaller size toward a distal end thereof than adjacent to a proximal end thereof. The core wire has a tip member disposed at the distal end of the elongate tapered body. A coil is positioned over the core wire. The coil is coupled to a proximal portion of the core wire. The tip member is heated to melt a distal portion thereof to form an atraumatic tip portion having a convex shape. The tip member has sufficient heat capacity to prevent material property changes in the core wire while allowing a distal portion to be formed having the convex shape following heating.

These and other features, aspects and advantages are described below with reference to the drawings, which are intended for illustrative purposes and should in no way be interpreted as limiting the scope of the embodiments. Furthermore, various features of different disclosed embodiments can be combined to form additional embodiments, which are part of this disclosure. In the drawings, like reference characters denote corresponding features consistently throughout similar embodiments. The following is a brief description of each of the drawings.

This application is directed to improved design and construction techniques for pressure guidewires. Such techniques provide robust connections between separate structures enhancing and fracture resistance. Such techniques provide connections that protect delicate structures from damage caused by stress concentration resulting from material degradation within localized heat affected zone(s), such as can arise during welding and other heat generating manufacturing steps.

<FIG> and <FIG> illustrate a lesion diagnostic system <NUM> and the use thereof in the vasculature of a patient. <FIG> illustrates the left side coronary vasculature with a pressure guidewire <NUM> disposed in a proximal portion of a left anterior descending artery (LAD). The pressure guidewire <NUM> is positioned in the left anterior descending artery LAD with a distal portion thereof distal to an occlusion OCL. The pressure guidewire <NUM> is positioned through a guide catheter <NUM> that can be positioned in the aorta, for example. The blood flow in the left anterior descending artery LAD is on average from proximal to distal, through the occlusion OCL and over the distal tip of the pressure guidewire <NUM> when the guidewire <NUM> is placed as shown. The occlusion OCL obstructs flow to at least some extent. The lesion diagnostic system <NUM> is configured to determine whether the vessel is obstructed to an extent that balloon angioplasty, a stent or other catheter intervention ought to be performed.

<FIG> shows that the pressure guidewire <NUM> disposed at a distal end of the diagnostic system <NUM> and a monitor assembly <NUM> is positioned at an end opposite of the pressure guidewire <NUM> in the system <NUM>. The monitor assembly <NUM> can be disposed at a proximal end of the diagnostic system <NUM>. The distal end of the diagnostic system <NUM> is the end that is adapted to be positioned in the patient, e.g., in the left anterior descending artery LAD as discussed above. The proximal end of the diagnostic system <NUM> includes the portion near the cardiologist and in the case of the monitor assembly <NUM> outside the patient. One or more devices can be used to connect the pressure guidewire <NUM> to the monitor assembly <NUM>. As discussed more below, the pressure guidewire <NUM> can be configured to measure pressure using an optical sensor. In such embodiments the pressure guidewire <NUM> can be coupled to the monitor assembly <NUM> by a handle <NUM> and a fiber optic interface cable <NUM>. The fiber optic interface cable <NUM> conveys the optical signal from the pressure guidewire <NUM> to the monitor assembly <NUM>. The handle <NUM> couples the fiber optic interface cable <NUM> to the monitor assembly <NUM>.

In one approach, the monitor assembly <NUM> and the handle <NUM> are reusable components of the diagnostic system <NUM>. The pressure guidewire <NUM>, the fiber optic interface cable <NUM> or both can be disposable components. In some variations, the handle <NUM> and the fiber optic interface cable <NUM> are a single unit.

<FIG> shows the overall configuration of a pressure guidewire <NUM> according to one embodiment. The pressure guidewire <NUM> can include a shaft tube assembly <NUM> that includes a proximal section <NUM>, a middle section <NUM>, a sensor housing section <NUM>, and a tip assembly <NUM>. Shaft tube assembly 120A, illustrated in <FIG> and corresponding text describe additional embodiments of the pressure guidewire <NUM>. These components extend along and define outer surfaces of the pressure guidewire <NUM>. The construction and design of the pressure guidewire <NUM> is improved by providing two or more components forming the outer surface of the wire, e.g., in the proximal section <NUM> and in the middle section <NUM>. As discussed below, the pressure guidewire <NUM> is formed by joining a first annular face <NUM> of a proximal tubular member to a second annular face <NUM> of a distal tubular member. An advantageous connection is provided between the proximal section <NUM> and the middle section <NUM>. An advantageous connection is provided in the sensor housing section <NUM>. Improved assemblies are provided in the tip assembly <NUM>.

<FIG>, and <FIG> show features of the proximal section <NUM>. The proximal section <NUM> includes a first tubular body <NUM> that extends between a proximal end <NUM> and a distal end <NUM> of the proximal section <NUM>. The tubular body <NUM> includes a proximal outside surface <NUM> and a proximal inside surface <NUM>. The proximal outside surface <NUM> of the tubular body <NUM> defines a proximal portion of an outside surface of the pressure guidewire <NUM>. The diameter of the proximal outside surface <NUM> is configured to enable the guidewire <NUM> to enable a therapy catheter to be slideably advanced thereover, e.g., between the proximal outside surface <NUM> and an inside surface of the guide catheter <NUM>. The proximal outside surface <NUM> can be between <NUM> and <NUM>, e.g., in one embodiment about <NUM>.

The proximal inside surface <NUM> can be sized to enable a signal conductor <NUM> extend therethrough. The signal conductor <NUM> can extend through a central lumen <NUM> disposed within the proximal inside surface <NUM>. The proximal inside surface can have a size close to that of the signal conductor <NUM>. The thickness of the wall of the proximal section <NUM> between the outside surface <NUM> and the inside surface <NUM> can be about <NUM>. An inner diameter of the proximal section <NUM> can be between <NUM> and <NUM>, e.g., about <NUM> in one embodiment. The size of the lumen <NUM> can be between <NUM> and <NUM>, e.g., about <NUM> in one embodiment. In one embodiment, the diameter of the lumen <NUM> can be less than the combined thickness of the wall of the proximal section <NUM> on opposite sides of the lumen <NUM>. The diameter of the lumen <NUM> can be between <NUM>% and <NUM>% of the combined thickness of the wall of the proximal section <NUM> on opposite sides of the lumen <NUM>. The diameter of the lumen <NUM> can be between <NUM>% and <NUM>% of the combined thickness of the wall of the proximal section <NUM> on opposite sides of the lumen central lumen <NUM>, e.g., about <NUM>% in some examples. A clearance gap between the inside surface <NUM> and an outside surface of the signal conductor <NUM> can be at least about <NUM>, e.g., about <NUM>.

The proximal section <NUM> provides an improved proximal section configuration in enabling the signal conductor <NUM> to be centrally disposed in a central lumen <NUM> of the pressure guidewire <NUM>. The proximal section <NUM> can be configured to provide sufficient support in the proximal section <NUM> such that the pressure guidewire <NUM> can be assembled without any core wire or similar reinforcement structures in the proximal section <NUM>. The thickness of the wall of the proximal section <NUM> provides sufficient mechanical performance, e.g., pushability, torqueability, and kink resistance without additional reinforcement. The proximal section <NUM> can include a continuously concave surface <NUM> disposed around signal conductor <NUM>. A continuously concave surface <NUM> can be formed by the proximal inside surface <NUM> of the proximal section <NUM> in one embodiment. The continuously concave surface <NUM> can be separated from the signal conductor <NUM> by only an annular gap therebetween.

The proximal section <NUM> can be configured such that the tubular body <NUM> has a first thickness <NUM> between the proximal outside surface <NUM> and the proximal inside surface <NUM>. The first thickness <NUM> can be sufficient to provide the support needed to avoid any kinking or fracture that would render the pressure guidewire <NUM> inoperative. The first thickness <NUM> can be substantially constant from the proximal end <NUM> to the distal end <NUM>. <FIG> shows that the tubular body <NUM> can have a first annular face <NUM> at the distal end <NUM>. The first annular face <NUM> is configured to couple with a second annular face <NUM> of the middle section <NUM> at a junction <NUM> between the proximal section <NUM> and the middle section <NUM> as discussed further below.

<FIG>, and <FIG> show details of the middle section <NUM>. The middle section <NUM> includes a proximal end <NUM> and a tubular body <NUM> that extends from the proximal end <NUM> to a distal end. The distal end can be coupled the sensor housing section <NUM> in one embodiment. In another embodiment, the distal end of the middle section <NUM> can extend into and form a portion, e.g., the outer surface, of the sensor housing section <NUM>.

The tubular body <NUM> has a middle section outside surface <NUM> and a middle section inside surface <NUM>. The middle section outside surface <NUM> can form a portion of an outside surface of the pressure guidewire <NUM>. <FIG> and <FIG> show that the middle section outside surface <NUM> and the proximal outside surface <NUM> of the proximal section <NUM> can form a substantially continuous outer surface of the pressure guidewire <NUM> from the distal end <NUM> of the proximal section <NUM> to the proximal end <NUM> of the middle section <NUM>. The tubular body <NUM> can have an outside diameter defined by the middle section outside surface <NUM> that is the same or substantially the same as the diameter of the proximal outside surface <NUM>. The middle section <NUM> can have an outside diameter between <NUM> and <NUM>, e.g., about <NUM>, about <NUM>, about <NUM>, and about <NUM> in various embodiments.

The tubular body <NUM> can be configured to enable the pressure guidewire <NUM> to have enhanced flexibility in the middle section <NUM>.

The middle section <NUM> can be made significantly more flexible by forming at least a portion of the tubular body <NUM> into a discontinuous configuration, e.g., a ribbon, a spiral, a coil or other suitable configuration. A ribbon configuration (<FIG>) can be formed by spiraling ribbon <NUM>, preferably a square or rectangular ribbon, with spacing <NUM>. Ribbon can preferably be made of stainless steel, cobalt chrome or other metal, or it can be made of polymer ribbon such as by way of examples Teflon™, polyimide(PI), polyvinyl chloride (PVC), polypropylene (PP), polyethylene (PE), polystyrene (PS), nylon, polyethylene terephthalate (PET), polycarbonate (PC), acrylonitrile butadiene (ABS), polyetheretherketone (PEEK), polyether block amide (PEBA) and polyurethane (PU). The ribbon or other metal structures of the pressure guidewire <NUM>, including the proximal section <NUM>, can include materials such as stainless steel, such as 304V, <NUM>, and 316LV stainless steel, <NUM>-7PH stainless steel, mild steel, nickel-titanium alloy such as linear-elastic and/or super-elastic nitinol. Also, other nickel alloys such as nickel-chromium-molybdenum alloys (e.g., UNS: N06625 such as INCONEL@ <NUM>, UNS: N06022 such as HASTELLOY@ UNS: N10276 such as HASTELLOY® C276. , other HASTELLOY@ alloys, and the like), nickel-copper alloys (e.g., UNS: N04400 such as MONEL® <NUM>, NICKELVAC® <NUM>, NICORROS® <NUM>, and the like), nickel-cobalt-chromium-molybdenum alloys (e.g., UNS: R30035 such as MP35-N. and the like), nickel-molybdenum alloys (e.g., UNS: N10665 such as HASTELLOY@ ALLOY B2@), other nickel-chromium alloys, other nickel-molybdenum alloys, other nickel-cobalt alloys, other nickel-iron alloys, other nickel-copper alloys, other nickel-tungsten or tungsten alloys, and the like; cobalt-chromium alloys; cobalt-chromium-molybdenum alloys (e.g., UNS: R30003 such as ELGILOY®, PHYNOX@, and the like), platinum enriched stainless steel, titanium, combinations thereof, and the like, or any other suitable material can be used. Proximal end face <NUM> of ribbon <NUM> can be flattened to adapt to distal end face of proximal section <NUM>. A spiral configuration (<FIG>) can be made by laser cutting a spiral shaped gap <NUM> in at least a portion <NUM> of the middle section <NUM> preferably made of stainless, other metal or polymer tubular body. A coil configuration (<FIG>) can be made by coiling a wire <NUM> preferably made of stainless steel, platinum, palladium or other platinum or palladium based metal, other metal or polymer to form the middle section.

The middle section <NUM> can be reinforced to enhance or even optimize torque transfer, pushability, support, kink and/or fracture resistance of the pressure guidewire <NUM> in the middle section <NUM>. In one embodiment, a hypotube <NUM> can be positioned in the middle section <NUM>. <FIG> shows that the hypotube <NUM> can extend from proximal of a ribbon, spiral or coil portion of the tubular body <NUM> to distal of the ribbon, spiral or coil portion. The hypotube <NUM> can have an inside surface forming a portion of the central lumen <NUM> of the pressure guidewire <NUM>. The inside surface of the hypotube <NUM> can form a diameter that is substantially the same as the inside diameter of the tubular body <NUM> of the proximal end <NUM>. Preferably, the inside diameter of the hypotube <NUM> can be made to accommodate the outside diameter of the signal conductor <NUM>. The inside diameter of the hypotube <NUM> can be between <NUM> and <NUM>, e.g., about <NUM> in one embodiment. The central lumen <NUM> can have a substantially constant inner diameter in one embodiment, e.g., from the proximal end to the distal end of the pressure guidewire <NUM>. In one variation, the inside diameter of the hypotube <NUM> can be smaller than the inside diameter of the tubular body <NUM> such that a clearance between an outside surface of the signal conductor <NUM> and the inside surface of the hypotube <NUM> is smaller than a clearance between the outside surface of the signal conductor <NUM> and the inside surface of the tubular body <NUM>. A greater clearance between the signal conductor <NUM> and tubular body <NUM> can allow the optical fiber <NUM> to be more easily advanced through the tubular body <NUM>. On the other hand, the inside diameter of the hypotube <NUM> can be smaller than the inside diameter of the tubular body <NUM> such that hypotube <NUM> wall thickness can be made thicker.

In another embodiment shown in <FIG>, the middle section <NUM> is made by cutting a spiral <NUM> along at least a portion of the middle section. The cut <NUM> is preferably made throughout the whole thickness of the wall of the tubular body in the middle section <NUM>. In one variation, the cut <NUM> partially goes through the wall of the tubular body to modify the flexibility of the middle section <NUM>. The proximal end face <NUM> of middle section <NUM> can be butt coupled to distal end face of proximal section <NUM> to form a junction <NUM>. Butt coupling assembly method includes direct laser welding, soldering and other methods. Proximal end of hypotube <NUM> can be joined to proximal end of middle section tubular body <NUM> by providing adhesive <NUM> between the outside surface of the hypotube <NUM> and the inside surface of middle section tubular body <NUM>. The tubular body <NUM> may include an opening <NUM> facilitating the migration of adhesive within the proximal region where hypotube is joined to middle section.

In another embodiment shown in <FIG>, the inside diameter of the proximal section <NUM> is not constant. More specifically, the inside diameter of the distal portion of the proximal section <NUM> can be enlarged to accommodate the hypotube <NUM>, the remaining proximal inside diameter <NUM> being smaller and accommodating the signal conductor, e.g., the optical fiber <NUM>. The enlarged inside diameter portion can be as short as <NUM> or less, it can be as long as <NUM> or more, the length is preferably around <NUM> to <NUM> long. The enlarged portion can be drilled using a drill bit, a laser beam or other methods known in the art. The hypotube <NUM> is preferably joined to and within the distal enlarged portion of proximal section <NUM> using adhesive <NUM>. The distal portion <NUM> may include an opening <NUM> to facilitate the migration of adhesive <NUM> between the outside surface of hypotube and inside surface of enlarged portion of proximal section. The middle section <NUM> can be made of a ribbon, a spiral or a coil configuration. The proximal end face of the middle section can be butt coupled to the distal end face of proximal section. The proximal portion of the middle section can also be joined to the proximal portion of the hypotube by using adhesive between their respective inside and outside proximal surfaces. The middle section <NUM> can also be joined by butt coupling to proximal section <NUM>. The middle section <NUM> can be bonded to hypotube with an adhesive as described above.

In another embodiment shown in <FIG>, a coupler <NUM> is attached to the distal end of the proximal section <NUM>. The coupler <NUM> has an inside diameter to accommodate the hypotube <NUM>. The coupler <NUM> can be as short as <NUM> or less, it can be as long as <NUM> or more, the length is preferably around <NUM> to <NUM> long. The proximal end face of the coupler <NUM> can be butt coupled distal end face of proximal section <NUM> to form a junction <NUM>. The proximal end of the hypotube <NUM> can be joined to and within the coupler <NUM> using adhesive <NUM>. The coupler <NUM> may include an opening <NUM> to facilitate the migration of adhesive <NUM> between the outside surface of hypotube <NUM> and inside surface of coupler <NUM>. The middle section <NUM> can be made of or can include a ribbon, a spiral or a coil configuration. The proximal end face of the middle section <NUM> can be butt coupled to the distal end face of coupler <NUM>. The proximal portion of the middle section can also be joined to the proximal portion of the hypotube <NUM> by using adhesive between their respective inside and outside proximal surfaces. The middle section <NUM> can also be joined by butt coupling to proximal section <NUM>. The middle section <NUM> can be bonded bonding to hypotube <NUM> with an adhesive as described above.

The hypotube <NUM> can be shaped to provide a varying flexibility along the length of the hypotube <NUM> and therefore along the length of the middle section <NUM>. Preferably, the outside surface of the hypotube <NUM> has an increasingly reduced outside diameter forming a tapered portion that is localized toward the distal end of the hypotube. The hypotube <NUM> can include a distal end portion <NUM> that is cylindrical and that is enlarged compared to a tapered portion <NUM> of the hypotube <NUM> as shown in <FIG>. The purpose of the enlarged section <NUM> can be for joining distal end of hypotube <NUM> to the inside surface of the proximal end of sensor housing <NUM>. The sensor housing <NUM> can be a separate tubular body from the tubular body of the middle section <NUM>. The enlarged section <NUM> can also be joined to the inside surface of sensor housing <NUM> at a proximal end thereof. The sensor housing <NUM> can be the continuation of tubular body of middle section <NUM>. The hypotube <NUM> can have a cylindrical portion proximal of a tapered section, as shown in <FIG> and <FIG>. The hypotube <NUM> can be made of a highly elastic or a super elastic material, such as nickel-titanium alloy (nitinol). Other materials that could be used or the hypotube <NUM> include stainless steel, cobalt-chrome, and other materials with elasticity in the expected strain regime.

The manner of forming the junctions <NUM>, <NUM>, and <NUM> is important for maintaining the structural integrity of the pressure guidewire <NUM>. The junction <NUM> can include a junction between the tubular body <NUM> of the proximal section <NUM> to the tubular body <NUM> of middle section <NUM>. The junction <NUM> can include a junction between the hypotube <NUM> and the tubular body <NUM>. The junction <NUM> can include a junction between the hypotube <NUM> and the tubular body <NUM> of the proximal section <NUM>. The junction <NUM> can include a junction between the distal end of proximal section <NUM> and the proximal end of middle section <NUM>. The junction can include a junction between the distal end of proximal section <NUM> and the proximal end of tubular body of middle section <NUM>. The junction can include a junction between the distal end of proximal section <NUM> and the proximal end of coupler <NUM>. The junction can include a junction between the distal end of coupler <NUM> and the proximal end of tubular body of middle section <NUM>.

In one embodiment an adhesive <NUM> is provided between an outside surface of the distal end portion <NUM> of the hypotube <NUM> and the middle section inside surface <NUM>. A seal, e.g., by way of an adhesive, can be provided between the outside surface of the distal end portion <NUM> of the hypotube <NUM> and the middle section inside surface <NUM>. In one embodiment an adhesive <NUM> is provided between an outside surface of a proximal portion of the hypotube <NUM> and the middle section inside surface <NUM>, adjacent to the proximal end <NUM>. A seal can be provided between the outside surface of the proximal portion of the hypotube <NUM> and the middle section inside surface <NUM>, adjacent to the proximal end <NUM>. In one embodiment the adhesive <NUM> also provides a seal between the outside surface of the proximal portion of the hypotube <NUM> and the middle section inside surface <NUM> adjacent to the proximal end <NUM>.

<FIG> shows details of a junction <NUM>. The junction <NUM> can be formed between the proximal section <NUM> and the middle section <NUM>. The tubular body <NUM> of the proximal section <NUM> has a first annular face <NUM>. The tubular body <NUM> of the middle section <NUM> has a second annular face <NUM> or a coupler, such as any of those disclosed herein, e.g., in <FIG>. The first annular face <NUM> and the second annular face <NUM> are secured together at the junction <NUM>. <FIG> shows that the first thickness <NUM> at the first annular face <NUM> may be greater than the second thickness <NUM> at the second annular face <NUM>. The first annular face <NUM> and the second annular face <NUM> can be joined by any suitable technique. In one embodiment a weld zone <NUM> is provided between the tubular body <NUM> of the proximal section <NUM> and the tubular body <NUM> of the middle section <NUM>. The weld zone <NUM> is shown as a short cylinder section mainly for illustration purposes. The weld zone <NUM> can be a weld line formed when laser welding as the first annular face <NUM> and the second annular face <NUM> are held together or adjacent to each other. The junction <NUM> can comprise a butt junction. The junction <NUM> can be formed between any two tubular bodies <NUM> and <NUM>, including between proximal sections <NUM>, <NUM> and <NUM> and middle sections <NUM> and <NUM> or coupler <NUM>.

In addition to forming the weld zone <NUM> in connecting two tubular bodies <NUM> and <NUM> at the junction <NUM>, in some embodiments the junction <NUM> is configured to enhance kink or fracture resistance. In some laser welding techniques a laser weld can affect the mechanical properties of welded materials. More specifically, the elastic modulus, tensile strength, yield strength or a combination of the same can be negatively affected within the heat affected zone. The change in mechanical properties can soften the material. Typical laser welding joint can be very localized, i.e. the heat affected zone can be very localized at the junction. When mechanically challenged, for example if the device is bent within or around the junction, most of the strain (deformation) ends up concentrating in the very localized region of heat affected zone 151C. The risk of fracture therefore increases quite significantly. In one approach a ductility enhancement zone 151A is provided on the tubular body <NUM> of the middle section <NUM>. The ductility enhancement zone 151A can extend along a length of the tubular body <NUM> of the middle section <NUM> from the proximal end <NUM> toward the distal end of the tubular body <NUM>. The ductility enhancement zone 151A can extend at least about a distance equal to the outer diameter of the middle section <NUM>. The ductility enhancement zone 151A can extend at least about a distance equal to about two times, three times, four times, or five times the outer diameter of the middle section <NUM>. The ductility enhancement zone 151A can extend from the proximal end <NUM> at least <NUM>% of the distance to the ribbon portion of the middle section <NUM>. The ductility enhancement zone 151A can extend from the proximal end <NUM> at least <NUM>% of the distance to the ribbon portion of the middle section <NUM>. The ductility enhancement zone 151A can extend from the proximal end <NUM> at least <NUM>% of the distance to the ribbon portion of the middle section <NUM>. The ductility enhancement zone 151A can extend from the proximal end <NUM> at least <NUM>% of the distance to the ribbon portion of the middle section <NUM>.

In one embodiment, the junction <NUM> is configured such that a ductility enhancement zone 151B is provided in the tubular body <NUM> of the proximal section <NUM>. The ductility enhancement zone 151B is similar to the ductility enhancement zone 151A and can extend from the distal end <NUM> proximally toward the proximal end <NUM>. The ductility enhancement zone 151B can have a length similar to or the same as the ductility enhancement zone 151A.

In another embodiment, the junction <NUM> is configured such that a ductility enhancement zone is provided in the coupler <NUM> and/or in the distal region of proximal section <NUM>. The junction is configured such that a ductility enhancement zone is provided in the region of proximal section <NUM> where inside diameter suddenly decreases.

In one embodiment, a ductility enhancement zone 151C can be provided at the weld zone <NUM>. In other words, a portion or all of the weld line or zone can be provided with the weld zone <NUM>.

The junction <NUM> can have a ductility enhancement zone that can include at least a portion of the tubular body <NUM>, at least a portion of the tubular body <NUM>, or at least a portion of the weld zone <NUM>. The weld zone ductility enhancement zone <NUM> extend from proximal of the first annular face <NUM> to distal of the second annular face <NUM>. Ductility can be provide above a threshold level from the ductility enhancement zone 151B, through the ductility enhancement zone 151C and into the ductility enhancement zone 151A. The ductility enhancement zone 151C can have a ductility less than an initial (pre-treatment) ductility. The post treatment ductility can be about <NUM>% of the pre-treatment ductility, in some cases between <NUM> and <NUM>% of the pre-treatment ductility, in some cases between <NUM> and <NUM>% of the pre-treatment ductility, in some cases between <NUM> and <NUM>% of the pre-treatment ductility, in some cases between <NUM> and <NUM>% of the pre-treatment ductility. Ductility can be as measured using a three point bend test, as is known to those skilled in the art.

The hypotube <NUM> can be secured in the pressure guidewire <NUM> by one or more adhesive joints as discussed above. The hypotube <NUM> can be secured in the junction <NUM> as well. The hypotube <NUM> can be secured at the weld zone <NUM>. A proximal face of the hypotube <NUM> can be joined to the first annular face <NUM> of the tubular body <NUM>. In other words, the second annular face <NUM> and the proximal face of the hypotube <NUM> can both be welded to the tubular body <NUM>.

One method for enhancing the ductility of the junction <NUM> is to provide a localized heat treatment of at least a portion of the pressure guidewire <NUM> including the junction <NUM>. An example of a heat treatment is to heat the welded region to a temperature above or around the annealing temperature. More specifically, heat treatment can include heating junction <NUM> to a temperature of or around <NUM> for a short period of time and let it cool in air.

<FIG> show details of the sensor housing section <NUM>. The sensor housing section <NUM> comprises a portion of the pressure guidewire <NUM> where a sensing device is placed in pressure communication with blood in a blood vessel in the use of the pressure guidewire <NUM> as discussed in connection with <FIG>. The sensor housing section <NUM> includes a tip pressure sensor <NUM>. The tip pressure sensor <NUM> can include a MEMS sensor unit that is able to detect pressure. The MEMS sensor unit is one example of a detector. The MEMS sensor unit can be a device mounted on a small tubular body made of glass, metal or another material. The MEMS sensor unit can include or can be coupled to the optical fiber assembly. The MEMS sensor unit can be integrated into a sensor body <NUM>. The sensor body <NUM> can include one or more functions, such as minimizing assembly induced stresses, e.g., by providing a flat bonding surface that allows a thin layer of adhesive retaining a sensor, aligning the sensor within a tube of the pressure guidewire <NUM>, preventing adhesive from reaching the sensor when assembling the sensor to the internal surface of a tubular body, and other functions. The MEMS sensor can employ an optical detection principle. The tip pressure sensor <NUM> can be disposed in the sensor housing section <NUM> in a location to be in pressure communication with blood in a vessel. The tip pressure sensor <NUM> can include a delicate structure that requires a secure connection in the pressure guidewire <NUM> and also requires the sensor not be damaged in the manufacturing process. The tip pressure sensor <NUM> can be secured with a ring member <NUM>. The ring member <NUM> can be secured to the optical fiber <NUM>, nearby and proximal to a sensor body <NUM> of the tip pressure sensor <NUM>. The ring member <NUM> can be secured by an adhesive layer <NUM> disposed between the ring member <NUM> and the optical figure <NUM>.

<FIG> shows that the adhesive layer <NUM> can be an annular layer between the ring member <NUM> and the optical fiber <NUM>. The adhesive layer <NUM> can be positioned to substantially center the sensor body <NUM> and the fiber <NUM> relative to the ring member <NUM>. The ring member <NUM> can hold the sensor body <NUM> of the tip pressure sensor <NUM> securely in position in the sensor housing section <NUM>. <FIG> shows that the sensor housing section <NUM> can have an outer tubular body <NUM> that can be separate from or can be an integral extension of the tubular body <NUM> of the middle section <NUM>. The outer tubular body <NUM> can have the ring member <NUM> disposed therein. The ring member <NUM> can be substantially centered in the outer tubular body <NUM>. The ring member <NUM> can be held in the outer tubular body <NUM> by a material bridge <NUM> extending between an outside surface of the ring member <NUM> and an inside surface of the outer tubular body <NUM>. The material bridge <NUM> can be a separate material, such as an adhesive, in one embodiment. In another embodiment, the material bridge <NUM> is a fused weld line between the ring member <NUM> and the outer tubular body <NUM>.

The ring member <NUM> can be made of various materials such as polymer, glass or metal. In one embodiment, the ring member <NUM> can include a metal ring. The metal ring can be bonded to a glass structure such as a glass ring that can be part of the sensor body <NUM>. In one case, the ring member <NUM> can include a metal ring that is bonded to a glass ring that is further coupled to the sensor body <NUM> which may or may not include another glass ring for holding a MEMS sensor unit or structure. The ring member <NUM> can be made of a material that can be fused welded/bonded to the inside surface of the sensor housing by way of localized sensor housing heating. Preferably, the ring member is made of a metal that can be fused or welded to the sensor housing such as stainless steel. Laser beam or beams can be used to heat and form the material bridge <NUM> to secure the ring member <NUM> to the outer tubular body <NUM>. Directing laser welding energy toward or around the ring member <NUM> can result in damage to the sensor body <NUM> or optical fiber <NUM>. Therefore the material bridge <NUM> is configured to protect or is formed in a manner that protects the sensor body <NUM> and the optical fiber <NUM> from damage in the coupling process, e.g., due to the laser welding.

A coupling zone <NUM> is provided on the pressure guidewire <NUM>, in particular in the sensor housing section <NUM>. The coupling zone <NUM> is configured in a manner that prevents the laser welding energy from potentially affecting the optical fiber <NUM>. The coupling zone <NUM> can be limited to a portion of the cross-section of the sensor housing section <NUM> where the optical fiber <NUM> is not located, i.e. the coupling zone is offset from the central axis of the sensor housing section where the optical fiber <NUM> resides. The coupling zone <NUM> can be so limited in a method in which the ring member <NUM> is joined to the outer tubular body using a laser welding process. The laser can be directed in a direction that is toward an exterior surface of the ring member <NUM> but that is not in a direction toward the optical fiber <NUM>.

A welding process can be defined that limits the location for application of energy within a boundary. The boundary can be defined as a portion of a cross-section of the sensor housing section <NUM> that does not intersect the optical fiber <NUM>. The direction of the laser beam is offset from the central axis of the sensor housing where the optical fiber resides. The propagation of heat toward the optical fiber is therefore minimized.

The foregoing methods can be used to form the material bridge <NUM> (e.g., a weld line). The material bridge <NUM> is disposed between an inner surface of an outer tubular body <NUM> and an outer surface of the ring member <NUM>. The outer tubular body <NUM> can be a span the tubular body that forms the middle section <NUM> and the outer surface of the sensor housing section <NUM>. The material bridge <NUM> can span arc corresponding to an angle of at least <NUM> degrees of the outer surface of the ring member <NUM>. The material bridge <NUM> can span an angle of at least <NUM> degrees of the outer surface of the ring member <NUM>. The material bridge <NUM> can span an angle of at least <NUM> degrees of the outer surface of the ring member <NUM>. The material bridge <NUM> can span an angle of at least <NUM> degrees of the outer surface of the ring member <NUM>. The material bridge <NUM> can span an angle of at least <NUM> degrees of the inner surface of the outer tubular body <NUM>. The material bridge <NUM> can span an angle of at least <NUM> degrees of the inner surface of the outer tubular body <NUM>. The material bridge <NUM> can span an angle of at least <NUM> degrees of the inner surface of the outer tubular body <NUM>. The material bridge <NUM> can span an angle of at least <NUM> degrees of the inner surface of the outer tubular body <NUM>. The material bridge <NUM> can span an angle of between <NUM> degree and <NUM> degrees, between <NUM> degree and <NUM> degrees, and between <NUM> degree and <NUM> degrees.

The material bridge <NUM> can extend along an axial length of the ring member <NUM>, e.g., along at least <NUM> percent of the length of the ring member <NUM>. The material bridge <NUM> can extend at least <NUM> percent of the length of the ring member <NUM>. The material bridge <NUM> can extend at least <NUM> percent of the length of the ring member <NUM>.

For a guidewire to be easily steered within a vasculature, it is desirable to have an advantageous, e.g., an optimal, flexibility profile, more specifically it is desirable to reduce or minimize a disruption of a continuous flexibility profile. Continuous flexibility profile can be achieved, among other specific flexibility profile parameters, by reducing or minimizing the length of stiff regions along the guidewire. The sensor housing primary function is to protect the sensor from external mechanical stress that may otherwise compromise the stability of measurements. Sensor housing stiffness is therefore a desirable feature. In order to reduce or minimize the impact of the sensor housing on the flexibility profile, sensor housing length should be reduced or minimized as much as possible. Shortening the overall length of the sensor assembly and ring member is therefore paramount in some embodiments. Sensor assembly illustrated in <FIG> allows further shortening of the sensor assembly and hence of the sensor housing. The MEMS device <NUM> can be a portion of the sensor that includes a diaphragm and the base supporting the diaphragm. The diaphragm can be made of silicon while the base can be made of glass, usually Pyrex® or other glass compatible with anodic bonding to silicon. An advantageous sensor assembly would comprise the MEMS pressure portion <NUM> directly mounted on a ring member <NUM>. The ring member is preferably made of metal that can be fused welded to the inside of the sensor housing or other tubular body. A preferred embodiment would be a MEMS pressure device bonded to a distal face of a ring member made of stainless steel <NUM> or other metal, the signal conductor or the optical fiber would be bonded inside and through the ring member to reach an optical contact with the MEMS proximal surface.

<FIG> show the tip assembly <NUM> in greater detail. As discussed above the pressure guidewire <NUM> in inserted into the highly sensitive and delicate vasculature of a heart of a patient. Accordingly, the tip assembly <NUM> has to delicately engage the vascular tissue. Also, the tip assembly <NUM> has to be able to bend and flex in such interactions within kinking or fracturing. These requirements have resulted in very complex structures. The tip assembly <NUM> provides a streamlined design that at the same time protects the material properties of the components of the tip assembly <NUM>.

The tip assembly <NUM> includes a core wire <NUM> disposed within a coil <NUM>. The core wire <NUM> extends from a first (or proximal) end coupled with a distal end of the outer tubular body <NUM>. <FIG> shows that the proximal end of the core wire <NUM> can be inserted into a distal opening of the outer tubular body <NUM>. The proximal end of the core wire <NUM> can form a distal boundary of a sampling area <NUM> of the pressure guidewire <NUM>. The sampling area <NUM> is an area in which blood can enter the pressure guidewire <NUM> and be sensed by the sensor body <NUM>. The connection between the outer tubular body <NUM> and the proximal end of the core wire <NUM> can be done by any suitable technique, such as by laser welding.

The core wire <NUM> can have a tapered profile from a proximal portion to a distal portion as shown in <FIG> and <FIG>. <FIG> shows a more simplified embodiment of the core wire <NUM>. <FIG> shows that the core wire <NUM> can have a proximal portion <NUM> with a first outer diameter. The core wire <NUM> can have a profiled distal portion <NUM>. The profiled distal portion <NUM> can include a first proximal taper and a second distal taper. The core wire <NUM> of <FIG> can have an aperture to receive an end portion of the coil <NUM>. The proximal portion <NUM> can extend within the interior of the coil <NUM>.

<FIG> shows that the profiled distal portion <NUM> causes the core wire <NUM> to reduce dramatically in diameter. A small diameter of the core wire <NUM> in the distal portion thereof can be less than one-half the diameter of the core wire <NUM> in the proximal portion <NUM>. The small diameter of the core wire <NUM> in the distal portion thereof is less than one-fifth the diameter of the core wire <NUM> in the proximal portion <NUM>. The small diameter of the core wire <NUM> in the distal portion thereof can be less than one-eighth the diameter of the core wire <NUM> in the proximal portion <NUM>. The small diameter of the core wire <NUM> in the distal portion thereof is less than one-tenth the diameter of the core wire <NUM> in the proximal portion <NUM>.

While the tapering of the profiled distal portion <NUM> provides desirable flexibility at the distal end of the tip assembly <NUM> the small diameter in the distal portion limits the options for the connection of the core wire <NUM> to an atraumatic tip member <NUM> of the tip assembly <NUM>. This connection can be made by welding. Welding generates high heat that can degrade the performance of the core wire <NUM>. The atraumatic tip member <NUM> presents a safe initial contact member for the pressure guidewire <NUM> as it advances through the vasculature. This can protect the vessel itself and also vulnerable plaque in the vessel, which the pressure guidewire <NUM> may have to engage and cross.

The core wire <NUM> is configured to enable the connection of the atraumatic tip member <NUM> thereto with a welding process while protecting the properties and performance of the core wire <NUM>. Laser fusion welding can create the atraumatic tip member <NUM> from the core wire enlarged distal section <NUM> and the radiopaque coil <NUM>. Due to the slender nature of the core wire <NUM> at the profiled distal portion <NUM> the heat generated by the welding process could potentially alter the material properties of the tip assembly <NUM>. In particular, the core wire <NUM> is processed, e.g., cold worked to have high tensile and yield strengths to avoid fracture and unwanted plastic deformation. The heat of typical laser welding process would anneal the material to a point where these properties would be lost or compromised. The zone where the material properties are affected by the heating process is sometimes referred to herein as a heat affected zone (HAZ).

<FIG> shows that the core wire <NUM> can include a distal portion <NUM> that is configured to shield the slender portions of the profiled distal portion <NUM>, e.g., the narrowest section(s) such that their desirable material properties are preserved. The distal portion <NUM> includes an enlarged member of a length configured to absorb heat in the process of creating the atraumatic tip member <NUM> from the melting of the distal portion <NUM> and the radiopaque coil <NUM>. In one embodiment, the atraumatic tip member <NUM> has a recess configured to receive the distal portion <NUM>. The distal portion <NUM> can be placed in the recess of the atraumatic tip member <NUM>. After the distal portion <NUM> is advanced into the atraumatic tip member <NUM> energy can be applied to the distal portion <NUM> and the atraumatic tip member <NUM> to couple these components together. The size and length of the distal portion <NUM> prevents heat from propagating into the core wire reduced diameter section <NUM> by applying heat to the distal end of distal portion <NUM>, hence preventing extreme heat from propagating and reaching the narrow portion <NUM> of the core wire <NUM>. The distal portion <NUM> can be two times larger in diameter than the small diameter section of the profiled distal portion <NUM>. The distal portion <NUM> can be three times larger in diameter than the small diameter section of the profiled distal portion <NUM>. The distal portion <NUM> can be four times larger in diameter than the small diameter section of the profiled distal portion <NUM>. The distal portion <NUM> can be five times larger in diameter than the small diameter section of the profiled distal portion <NUM>. The distal portion <NUM> can be seven times larger in diameter than the small diameter section of the profiled distal portion <NUM>. The narrowest portion of the profiled distal portion <NUM> can be maintained below a temperature of that corresponds to a melting temperature or below an annealing temperature, such as by way of non-limiting example <NUM> degrees Celsius, for stainless <NUM> for example, while the distal portion <NUM> are melted with the radiopaque coil to create the atraumatic tip <NUM>. The narrowest portion of the profiled distal portion <NUM> can be prevented from exceeding the annealing temperature of the material used to avoid any degradation of the ultimate tensile strength of the tip assembly <NUM>.

In another embodiment, the corewire <NUM> is formed or grinded with a profile that includes the distal portion <NUM>. The distal portion <NUM> outside diameter is formed to fit within the coil <NUM>. Clearance between coil and distal portion allows the formation of the atraumatic tip member <NUM> by melting and fusing together the distal end portion <NUM> with the portion of the coil that covers the distal portion <NUM>. Any heat affected zone is kept away from the narrow portion <NUM> of the core wire <NUM> by fusing the distal end of the distal portion <NUM> to the coil. The distal portion is made of a length that results in a thermal gradient where the heat affected zone does not reach the proximal end of the distal end <NUM>, and therefore the narrow portion <NUM> of the core wire <NUM>.

The pressure guidewire <NUM> can also include a novel assembly for providing sealed flexibility in the middle section <NUM>. The middle section <NUM> can be configured with a spiral, ribbon section, or coil configuration, as discussed above. The spiral section can be disposed around a middle portion of the hypotube <NUM> as discussed above. The spiral, ribbon, or coil can be enclosed, at least partially, in an outer sleeve <NUM>. The outer sleeve <NUM> can be made of a suitable material. In one embodiment, the outer sleeve <NUM> is formed of PET. Other suitable materials can be used. <FIG> shows a portion of the middle section <NUM> with enhanced flexibility. The middle section <NUM> has a spiral cut portion, a ribbon or a coil as discussed above. <FIG> shows an outer portion of the middle section <NUM> and omits the hypotube <NUM> for clarity. The outer sleeve <NUM> includes an outer surface portion <NUM> and an expansion portion <NUM>. The outer surface portion <NUM> includes a tubular member that is mounted to an outside surface of the spiral portion of the middle section <NUM>. The expansion portion <NUM> can span between adjacent spiral sections of the spiral cut portion of the middle section <NUM>. The expansion portion <NUM> can extend down into the gap between adjacent spirals of the ribbon spiral cut or coil portion. The expansion portion <NUM> can include a flexible span of material having a length greater than a gap between adjacent spiral sections of the spiral cut portion. The gap, in an undeflected state, can be any value between <NUM> and <NUM>, e.g., <NUM> to <NUM>, <NUM> to <NUM>, <NUM> or any value at or between the end points of any of the foregoing ranges. The gap can vary from the foregoing nominal values in a deflected, e.g., curved or bent, state. These gap dimensions also apply to embodiments that include the spacing <NUM> and the spiral shaped gap <NUM> discussed above. The flexible span of the expansion portion <NUM> allows adjacent spirals of the spiral cut portion to move relative to each other such that the middle section <NUM> can flexibly and torque bend and thereafter contract to a straight configuration.

The outer sleeve <NUM> can be used to receive coating with specific characteristics along a portion of the middle section, such as hydrophilic coating or other coating. The outer sleeve <NUM> can be used to promote the adhesion of a coating on the outside surface of the middle section <NUM>. The outer sleeve <NUM> can also be used to prevent matter, such as a coating, from reaching and getting into the interface between the spiral cut, ribbon or coil portion of the middle section <NUM> and the hypotube <NUM>. The outer sleeve <NUM>, while keeping the interface between the outside surface of the hypotube <NUM> and the inside surface of the middle section <NUM> free from coating, ensure the hypotube <NUM> can freely rotate relative the middle section <NUM>, hence maintaining flexibility and torque transmission.

As used herein, the relative terms "proximal" and "distal" shall be defined from the perspective of the user of the system. Thus, proximal refers to the direction toward the user of the system and distal refers to the direction away from the user of the system.

Thus, such conditional language is not generally intended to imply that features, elements, and/or steps are in any way required for one or more embodiments.

The terms "approximately," "about," "generally," and "substantially" as used herein represent an amount close to the stated amount that still performs a desired function or achieves a desired result. For example, the terms "approximately," "about," "generally," and "substantially" may refer to an amount that is within less than <NUM>% of the stated amount, as the context may dictate.

The ranges disclosed herein also encompass any and all overlap, sub-ranges, and combinations thereof. Language such as "up to," "at least," "greater than," "less than," "between" and the like includes the number recited. Numbers preceded by a term such as "about" or "approximately" include the recited numbers. For example, "about four" includes "four".

Any methods disclosed herein need not be performed in the order recited. The methods disclosed herein include certain actions taken by a practitioner; however, they can also include any third-party instruction of those actions, either expressly or by implication. For example, actions such as "distally moving a locking element" include "instructing distal movement of the locking element.

Some embodiments have been described in connection with the accompanying drawings. However, it should be understood that the figures are not drawn to scale. Distances, angles, etc. are merely illustrative and do not necessarily bear an exact relationship to actual dimensions and layout of the devices illustrated. Components can be added, removed, and/or rearranged. Further, the disclosure herein of any particular feature, aspect, method, property, characteristic, quality, attribute, element, or the like in connection with various embodiments can be used in all other embodiments set forth herein. Additionally, it will be recognized that any methods described herein may be practiced using any device suitable for performing the recited steps.

It is to be understood that not necessarily all such advantages may be achieved in accordance with any particular embodiment.

Claim 1:
A pressure guidewire comprising:
a shaft tube assembly comprising:
a proximal section (<NUM>, <NUM>, <NUM>) comprising a first tubular body (<NUM>) comprising a proximal end (<NUM>), a distal end (<NUM>), a proximal outside surface (<NUM>) and a proximal inside surface (<NUM>), the proximal inside surface enclosing a proximal portion of a central lumen (<NUM>), the proximal outside surface comprising an outer surface of the pressure guidewire;
a middle section (<NUM>, <NUM>) comprising a proximal end (<NUM>), a middle section outside surface (<NUM>), a middle section inside surface (<NUM>), the middle section inside surface disposed about a space within the pressure guidewire, the proximal end of the middle section being separate from and coupled to the distal end of the proximal section;
a sensor housing section (<NUM>) extending distally relative to the middle section;
a hypotube (<NUM>) comprising a proximal end portion and a distal end portion, the hypotube extending through the space about which the middle section inside surface is disposed, the proximal end portion of the hypotube coupled with the distal end of the proximal section and the distal end portion of the hypotube being coupled to the sensor housing;
a tip pressure sensor (<NUM>) positioned in the sensor housing section; and characterized in:
an optical fiber centered within the pressure guidewire in the proximal section and centered within the hypotube in the middle section,
and in that the proximal inside surface comprises a first diameter and the middle section inside surface comprises a second diameter, the first diameter being less than the second diameter.