Stylet with improved penetration

Abstract

To improve one or more features of the threadability of stylets, more specifically, stylets to be assembled with a PICC.SOLUTION: A low torqueable or non-torqueable stylet should have a core wire. The core wire includes: a first pre-formed bend of a first angle of about 15-90°; a second pre-formed bend of a second angle of about 8-15°, the second pre-formed bend being distal to the first pre-formed bend, and the first pre-formed bend being longer than the second pre-formed bend; an intermediate portion extending between the first pre-formed bend and the second pre-formed bend; and a distal portion between the second pre-formed bend and a distal tip. The distal portion has a segment with a reduced width or reduced diameter that increases deflection of the distal tip. The stylet further has a navigation device.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] SUMMARY OF THE DISCLOSURE The present disclosure relates generally to stiffening wires or stylets for placing vascular catheters, and more particularly to low-torque or no-torque stiffening wires or stylets that provide improved threadability.

[0002] REFERENCE TO RELATED APPLICATIONS This application claims priority to U.S. Provisional Patent Application No. 63 / 086,583, filed October 1, 2020, which is incorporated by reference in its entirety. [Background technology]

[0003] A PICC (Peripherally Inserted Central Venous Catheter) is a catheter that is inserted into a vein in the upper arm and threaded into the superior vena cava (SVC). PICCs allow access to a large central vein near the heart, typically for administering medications or liquid nutrients. PICCs can help avoid the pain of frequent needle sticks and reduce the risk of irritation to the small veins in the arm.

[0004] The inventors have recognized a need for improving one or more characteristics of the insertability of stylets, and more specifically, stylets to be assembled with PICCs. PICCs are often inserted at the bedside without sophisticated equipment for visualizing the anatomy. While several novel devices are available that display the PICC's location on a monitor, this provides only an approximate guide to tip placement relative to an external device. The distal tip of the stylet still often encounters a wall of the vasculature before a sharp bend or bend and does not advance forward, for example, traveling up another branch of a vein that is not in the intended insertion path to the SVC and / or contacting the vein wall and looping back on itself. As a result, it may take several attempts to properly thread the PICC into the SVC, or the user may not even be able to properly place the PICC at all. The patient may then need to be transported to another part of the hospital to visualize the anatomy with more sophisticated equipment for inserting the PICC to its final location. The disclosed invention addresses one or more of these and / or other deficiencies in the prior art. Summary of the Invention

[0005] Thus, a first aspect of the present invention relates to a stylet having a core wire, the core wire including a first preformed bend at a first angle and a second preformed bend at a second angle, the second preformed bend being distal to the first preformed bend, the first angle being greater than the second angle, and the core wire including a thin segment distal to the second preformed bend and having a reduced width or diameter that increases the flexibility of the distal tip.

[0006] In some embodiments, the first angle is approximately 15-90° relative to the longitudinal axis of the stylet, and the arc length of the first preformed bend is approximately 3-7 inches (7.5-17.5 cm). In some embodiments, the second angle is approximately 8-15° relative to the longitudinal axis of the stylet, and the arc length of the second preformed bend is approximately 0.2-0.5 inches (0.5-1.3 cm). In some embodiments, the first and second preformed bends are collectively within 10 inches (25 cm) of the end of the distal tip of the core wire. In some embodiments, the first angle is approximately 60° relative to the longitudinal axis of the stylet, and the second angle is approximately 10° relative to the longitudinal axis of the stylet. In some embodiments, the first preformed bend is longer than the second preformed bend. In some embodiments, the first preformed bend has an arc length at least 4 inches (10 cm) longer than the second preformed bend. In some embodiments, the first preformed bend and the second preformed bend are coplanar. In some embodiments, the thin segment has a rounded and / or flattened cross-section. In some embodiments, the core wire has a distal segment located between the thin segment and the distal tip, the distal segment having a larger width or diameter than the thin segment. In some embodiments, the distal tip has a larger width or diameter than the distal segment. In some embodiments, the core wire includes a proximal tapered portion located proximal to the thin segment and a distal tapered portion located distal to the thin segment. In some embodiments, the proximal tapered portion is longer than the distal tapered portion. In some embodiments, the proximal tapered section includes a first tapered section and a second tapered section, the first tapered section tapering at a greater angle than the second tapered section. In some embodiments, the stylet further includes a tubular body fitted over the core wire. In some embodiments, a distal tip of the core wire extends distally of the tubular body, the distal tip transmitting an electrocardiogram (ECG) signal. In some embodiments, the tubular body includes an opening in a sidewall that allows fluid contact with the core wire.In some embodiments, the stylet further comprises a navigation device disposed within the tubular body and fitted over the core wire. In some embodiments, the navigation device comprises a conductive coil. In some embodiments, the stylet has minimal or no torque. In some embodiments, the core wire further comprises an intermediate section extending approximately 1-3 inches (2.5-7.5 cm) between the first preformed bend and the second preformed bend. In some embodiments, the core wire further comprises a distal section with a thin segment, the distal section extending approximately 1-2 inches (2.5-5 cm) from the second preformed bend to the end of the distal tip. In some embodiments, the stylet further comprises a housing member located at the proximal end of the core wire. In some embodiments, the core wire comprises a nickel-titanium alloy. In some embodiments, the distal tip is formed from one of a J-section, a basket, or a mesh. In some embodiments, the stylet is a component of an assembly that includes a second stylet that transmits ECG signals.In some embodiments, the stylet is a component of an assembly that includes a catheter.

[0007] In a second aspect of the present invention, there is provided a low or no-torque stylet comprising a core wire having a first preformed bend at a first angle of about 15-90° and a second preformed bend at a second angle of about 8-15°, the second preformed bend being distal to the first preformed bend, the first preformed bend being longer than the second preformed bend, the core wire having an intermediate portion extending between the first and second preformed bends, about 1-3 inches (2.5-7.5 cm), and a distal tip portion extending between the second preformed bend and the distal tip portion. and a distal section of approximately 1 to 2 inches (2.5 to 5 cm) located between the end of the core wire and the distal tip, the distal section having a narrow segment of reduced width or diameter that increases the flexibility of the distal tip, the first preformed bend and the second preformed bend being located together within 10 inches (25 cm) of the end of the distal tip of the core wire, and the stylet further comprising a navigation device disposed around the core wire and a tubular body disposed around the core wire and the navigation device.

[0008] A third aspect of the present invention relates to a stylet having a distal portion including a thin segment, a proximal tapered portion located proximal to the thin segment, and a distal tapered portion located distal to the thin segment, wherein the length of the proximal tapered portion is longer than the length of the distal tapered portion. In some embodiments, the length of the proximal tapered portion is at least twice the length of the distal tapered portion. In some embodiments, the length of the proximal tapered portion is less than about six times the length of the distal tapered portion. In some embodiments, the proximal tapered portion includes a first tapered portion and a second tapered portion, wherein the first tapered portion tapers at a greater angle than the second tapered portion. In some embodiments, the first tapered portion is located proximal to the second tapered portion. In some embodiments, the stylet has a second distal tapered portion located distal to the thin segment and a distal segment extending between the distal tapered portion and the second distal tapered portion. In some embodiments, the stylet further includes a navigation device fitted to the distal segment. In some embodiments, the length from the proximal end of the thin segment to the distal end of the stylet is about 1.6 inches or less (less than about 4 centimeters). In some embodiments, the length of the thin segment is longer than the length of the distal taper. In some embodiments, the length of the thin segment is longer than the length of the proximal taper. In some embodiments, the thin segment has a constant width or diameter. In some embodiments, the width or diameter of the distal tip of the stylet is substantially the same as the width or diameter of the proximal portion of the stylet. In some embodiments, the distal tip has rounded and / or tapered edges. In some embodiments, the stylet has a preformed straight configuration. In some embodiments, the stylet has a preformed curved configuration.

[0009] In order that the present invention may be readily understood, aspects of the invention are shown by way of example in the accompanying drawings. [Brief explanation of the drawings]

[0010] [Figure 1]1 is a diagram illustrating the vascular system of the human body. [Figure 2] 1 is a perspective view of a first embodiment of a stylet according to the present invention. FIG. [Figure 3] FIG. 3 is a side view of the distal portion of the stylet of FIG. 2. [Figure 4] FIG. 4 is a perspective view of a core wire and a distal portion of a tubular body of the stylet of FIGS. 2 and 3. [Figure 5] FIG. 5 is a side view of the core wire and distal portion of the tubular body of the stylet of FIGS. 2-4. [Figure 6] 6 shows the distal portion of the stylet of FIGS. 2-5 within a catheter being threaded through the vascular system of the human body of FIG. 1. FIG. [Figure 7] FIG. 7 is an isometric view of a housing member of the stylet of FIGS. [Figure 8A] FIG. 2 is a diagram of a second embodiment of a stylet according to the present invention. [Figure 8B] FIG. 2 is a diagram of a second embodiment of a stylet according to the present invention. [Figure 9] FIG. 10 is a side view of a third embodiment of a stylet according to the present invention. [Figure 10A] FIG. 10 is a diagram of a fourth embodiment of a stylet according to the present invention. [Figure 10B] FIG. 10 is a diagram of a fourth embodiment of a stylet according to the present invention. [Figure 11A] FIG. 10 is a diagram of a fifth embodiment of a stylet according to the present invention. [Figure 11B] FIG. 10 is a diagram of a fifth embodiment of a stylet according to the present invention. [Figure 12] FIG. 11C is a side view of the stylet of FIGS. 11A and 11B. [Figure 13A] FIG. 10 is an isometric view of a sixth embodiment of a stylet positioned within a catheter in accordance with the present invention. [Figure 13B] FIG. 13B shows the distal end of the stylet and catheter of FIG. 13A. [Figure 14A] FIG. 14 shows a first variation of the stylet of FIGS. 13A and 13B. [Figure 14B]FIG. 14 shows a first variation of the stylet of FIGS. 13A and 13B. [Figure 14C] FIG. 14 shows a first variation of the stylet of FIGS. 13A and 13B. [Figure 15] FIG. 14 shows a second variation of the stylet of FIGS. 13A and 13B. [Figure 16] FIG. 10 is an isometric view of a seventh embodiment of a stylet positioned within a catheter in accordance with the present invention. [Figure 17] FIG. 10 is an isometric view of an eighth embodiment of a pair of stylets according to the present invention. [Figure 18] FIG. 18 shows a first assembly including a pair of stylets of FIG. 17 positioned within a catheter. [Figure 19] FIG. 18 shows a second assembly including a pair of stylets of FIG. 17 positioned within a catheter. DETAILED DESCRIPTION OF THE INVENTION

[0011] The same reference numbers are used in the drawings and the following detailed description to refer to the same or similar parts.

[0012] The present invention generally relates to stylets that provide a particular combination of bend and / or stiffness profile that enables a catheter to be threaded consistently through the anatomical curves of the vasculature and into a desired location in the vasculature. Stylets of the present invention may be low-torque or non-torque, allowing a user to thread the stylet without needing to know the orientation of the distal tip (i.e., the direction the tip is pointing, "up" or "down") or to control the orientation of the distal tip by turning the proximal end of the stylet. More specifically, the stylet may provide a consistent and desirable approach angle through the vasculature (e.g., at the confluence of the internal jugular, brachiocephalic, and / or subclavian veins) to a desired location. This approach angle may be desirable regardless of how the user inserts the catheter into the vasculature and / or how the user turns the proximal end of the catheter during insertion. The stylet may also have a narrow segment that is softer or more flexible than the rest of the stylet. The flexibility of the thin segment facilitates deflection of the distal tip when it contacts the vein wall, reducing trauma to the vein. Additionally, the thin segment allows the distal tip to bow upward when it contacts the vein wall, improving the contact angle of the distal tip so that it points downward in a desired direction. Commercial advantages include fewer insertion attempts, shorter insertion times, and less user frustration during insertion.

[0013] FIG. 1 is a reference anatomical diagram including the vasculature of potential routes through which a stylet in combination with a catheter (e.g., a peripherally inserted central venous catheter, PICC) can be passed into the superior vena cava (SVC) in accordance with the present invention. The stylet / PICC can enter the vasculature at a number of different venous locations, e.g., the basilic, brachial, or cephalic. The vasculature can be accessed at the optimal venous location by needle puncture, an access wire can be inserted through the needle and into the vasculature, and a sheath can be guided over the access wire after the needle is removed. After the access wire is removed from the sheath, the stylet / PICC can be passed through the sheath into the vasculature at the key venous location into the subclavian vein (SUB), and through it into the brachiocephalic vein (BCV, e.g., the right brachiocephalic vein, RBCV), and ultimately into the SVC. The most common area of ​​insertion difficulty is the confluence (C) where the SUB terminates and joins the internal jugular vein (IJ) and BCV, as further shown in Figure 6. The confluence (C) typically contains the sharpest curve in the anatomical pathway that can define a 90° turn or drop. Due to this sharp curve, the catheter may deviate in the wrong direction (e.g., up the IJ) or become trapped, preventing advancement altogether. While Figure 1 and the corresponding description relate to insertion of a stylet from the SUB into the RBCV, the stylet of the present invention can be inserted via other routes, including via the left brachiocephalic vein (LBCV).

[0014] Figure 2 is an isometric view of a stylet 100 in accordance with the present invention, and Figure 3 is a side view of the distal end of the stylet 100. As shown, the stylet 100 can include a housing member 102 located at the proximal end of an elongate body 104 configured for insertion into the vascular system. The elongate body 104 can include a core wire 120 and a tubular body 140 disposed about the core wire 120, as shown in Figures 4-6.

[0015] Core wire 120 may have a nominal or preformed shape, as shown in FIGS. 2 and 3 , that includes a preformed first curve or bend α (“body bend”). During insertion, first bend α may be forced to elastically straighten due to an anatomical insertion path that is straighter than the preformed core wire. When core wire 120 is straightened, it enters a high potential energy state and attempts to retract to a low potential energy state, similar to the way a stretched spring returns to its original, unstressed state. When distal tip 116 reaches confluence (C), the lowest potential energy state of first bend α causes distal tip 116 to point downward toward the SVC. The nominal shape and stiffness of elongate body 104 may be achieved by the preformed shape and stiffness of core wire 120. As shown, core wire 120 (and elongate body 104) can have a first portion 106 that is nominally substantially straight and extends distally from housing member 102. Core wire 120 (and elongate body 104) can have a second portion 108 that has a preformed first curve or bend α and extends distally from first portion 106. Core wire 120 (and elongate body 104) can have a third portion (or intermediate portion) 110 that is nominally substantially straight and extends distally from second portion 108. Core wire 120 (and elongate body 104) can have a fourth portion 112 that has a preformed second curve or bend β and extends distally from third portion 110. Core wire 120 (and elongate body 104) may be nominally substantially straight and may have a fifth section (or distal portion) 114 extending distally from fourth section 112 to distal tip 116. Thus, first bend α may be located proximal to second bend β and may be separated by third section 110.As further shown in FIG. 3, the first bend α may define a first angle between the longitudinal axes of the first and third portions 106, 110 of approximately 15 to 90 degrees (e.g., 55 to 70 degrees), such that the first bend α may define a coarse arc (as shown in FIG. 3) of approximately 90 to 165 degrees (however, unless otherwise specified, the angle of the first bend α is referred to herein as being between the longitudinal axes of the first and third portions 106, 110). The second bend β may define a second angle of approximately 8-15° between the longitudinal axes of the third section 110 and the fifth section 114, such that the second bend β may define a coarse arc of approximately 165-172° (as shown in FIG. 3 ) (however, unless otherwise specified, the angle of the second bend β is defined herein between the longitudinal axes of the third and fifth sections 110, 114). The angles of the first bend α and the second bend β may vary depending on the stiffness of the catheter (e.g., PICC) 150 disposed around the stylet 100. In other words, the catheter 150 may be nominally straight and may have some stiffness, allowing the catheter to straighten the stylet 100 at the first bend α and the second bend β. The stiffness of the catheter 150 may be determined by the brand, material, lumen, and size. For a rigid catheter 150, the stylet 100 may be curved to provide the proper angle with respect to the vasculature. Thus, the catheter 150 may be designed to provide an assembly of the stylet 100 and catheter 150 with a first portion at the first bend α having an angle of 5 to 80° and a second portion at the second bend β having an angle of 3 to 10°, each of which is relative to the longitudinal axis of the assembly. Thus, the assembly of the stylet 100 and catheter 150 is at an angle greater than the anatomical reference curvature.

[0016] Second section 108 can have an arc length of about 3 to 7 inches (about 7.5 to 17.5 cm), e.g., about 5.3 inches (about 13.5 cm), third section 110 can have a length of about 0 to 3 inches (about 0 to 7.5 cm), fourth section 112 can have an arc length of about 0.2 to 0.5 inches (about 0.5 to 1.25 cm), and fifth section 114 can have a length of about 1 to 2 inches (about 2.5 to 5 cm). Thus, in a preferred embodiment for inserting a PICC, first bend α can be a gradual bend at a first angle of about 60° beginning about 3 inches (about 7.5 cm) from the end of distal tip 116 and extending proximally to about 8.3 inches (about 21 cm) from the end of distal tip 116. The second bend β may form a second angle of approximately 10° by bending the stylet 100 around an approximately 0.25 inch (approximately 0.5 cm) diameter pin located approximately 1.25 inches (approximately 3 cm) from the end of the distal tip 116 to form an arc length of approximately 0.22 inches (approximately 0.5 cm).

[0017] Thus, the first angle of the first bend α (located between the first portion 106 and the third portion 110) can be substantially greater than the second angle of the second bend β (located between the third portion 110 and the fifth portion 114). For example, the difference between the first angle of the first bend α and the second angle of the second bend β can be at least 40°. Furthermore, the arc length of the second portion 108 (and the first bend α) can be substantially greater than the arc length of the fourth portion 112 (and the second bend β). For example, the difference in arc length between second section 108 (and first bend α) and fourth section 112 (and second bend β) can be at least 4 inches (approximately 10 cm), and first bend α and second bend β can collectively be within 10 inches (25 cm) of distal tip 116. Thus, second bend β can be close enough to distal tip 116 that when distal tip 116 is located at confluence (C), second bend β is located in a region of the reference anatomy (upstream / toward the insertion site) that has some curvature.

[0018] The first bend α may correspond to a body curve, and the second bend β may correspond to a tip curve, with the first and second bends α and β being in the same plane and in the same direction (to prevent reaction of the bends α and β). The first bend α may be configured to self-orient the stylet 100 into the anatomical structure, and the second bend β may be configured so that the first bend α self-orients the distal tip 116 at a desired angle to access difficult curved locations in the anatomical structure. Thus, the first and second bends α and β may enhance a user's ability to pass the stylet 100 to a desired location without visualizing the vein or steering the stylet 100. For example, as shown in FIG. 6 , the first and second bends α and β can be configured to automatically maintain the distal tip 116 at an approach angle that directs the distal tip 116 toward the lower portion of the posterior wall (BW) of the vasculature, thereby increasing the likelihood that the distal tip 116 will point downward toward the SVC. Additionally, the angle of the distal tip 116 reduces the risk of the distal tip 116 striking the posterior wall at a right angle, thereby preventing the distal tip 116 from bowing back on itself or "tenting" in a predictable manner. Furthermore, striking the distal tip 116 at a desired angle allows the distal tip 116 to strike the posterior wall (BW) of the vein at an angle and travel straight down the SVC without encountering excessive resistance to the user, thus reducing trauma to the posterior wall (BW).

[0019] The stylet 100 may be self-orienting in that manual rotation of the proximal housing member 102 does not substantially impart sufficient torque to the distal tip 116 to cause consistent rotation. Thus, the core wire 120 may be low or non-torque-sensitive. For example, a user may rotate the proximal housing member 102 multiple times, after which a significant amount of rotational motion is imparted to the distal tip 116, which may then rotate completely and quickly axially around and back to the desired location.

[0020] Thus, the first bend α may be configured to automatically align the stylet 100 with the curvature of the vasculature during insertion, with the purpose of having the distal tip 116 point “down” during RBVC because the first and second bends α and β are in the same plane and in the same direction. The distal tip 116 may always point down, for example, when entering a vascular confluence (C), where PICCs are most difficult to navigate through tight curvatures. The stylet 100 may be non-torqueable and non-steerable, thereby removing control of the orientation of the distal tip 116 from the user and allowing the stylet 100 to automatically find the correct orientation in the vasculature no matter how the stylet 100 is initially inserted and / or how the stylet 100 is rotated during insertion. Additionally, in some embodiments, the stylet 100 may include a torque limiting member (e.g., a torque limiting ground section) at the proximal end of the core wire 120 that further reduces the user's ability to transmit torque.

[0021] As further shown in FIGS. 4-6 , the fifth section 114 (including the distal tip 116) can have a thin segment 130 that is softer and more flexible than at least one or all of the proximal sections 106-112 of the stylet. The flexibility of the distal tip 116 allows the distal tip 116 to deflect upon contact with the venous wall without causing vascular trauma. Additionally, the thin segment 130 can bow upward upon contact with the venous wall, improving the contact angle of the distal tip 116 so that the distal tip 116 points downward toward the RBCV. The thin segment 130 can be straight and have a consistent width or diameter. The fifth section 114 can be short in length to provide desirable deflection mechanics. The proximal portions 106-112 of the core wire 120 need to have sufficient stiffness (greater than the thin segment 130) so that the shape of the core wire 120 will affect the stylet 100 after assembly, preventing the stylet 100 from easily bending during insertion. Thus, the stylet 100 has a stiffness profile such that the thin segment 130 of the fifth section 114 should be the first place along the length of the core wire 120 to bend, thereby allowing for a good insertion angle for the distal tip 116 while still preserving pushability of the assembly. If the proximal portions 106-112 of the core wire 120 bend prior to the thin segment 130 of the fifth section 114, longitudinal pushing force applied by the user will no longer be transmitted to the distal tip 116, thereby preventing the stylet 100 from advancing.

[0022] The thin segment 130 of the fifth section 114 may have a reduced width or diameter, which may be formed by a proximal taper 132 located at the proximal end that reduces the width or diameter of the stylet 100 from the fourth section 112 and / or a distal taper 134 located at the distal end that increases the width or diameter of the stylet 100 to the distal segment 136. The thin segment 130 may have a rounded and / or flattened cross-section. Thus, the distal taper 134 may connect the thin segment 130 to the distal segment 136, which is joined to the distal tip 116. In some embodiments, the distal segment 136 and the distal tip 116 may have a width or diameter that is greater than the width or diameter of the thin segment 130 and less than the width or diameter of at least one of the sections 106-112 (e.g., the remainder of the core wire 120). For example, portions 106-112 may have a width or diameter of approximately 0.011 inches (approximately 0.3 mm), distal segment 136 and distal tip 116 may have a width or diameter of approximately 0.007 inches (approximately 0.2 mm), and thin segment 130 may have a width or diameter of approximately 0.004 inches (approximately 0.1 mm). Proximal taper 132 may have a longer length and a more gradual slope than distal taper 134, allowing proximal taper 132 to withstand greater forces during insertion and prevent the development of stress risers / weak points that compromise the strength / performance of stylet 100. For example, proximal taper 132 can be at least about twice the length of distal taper 134 and less than about six times the length of distal taper 134 (e.g., at least three, four, or five times the length of distal taper 134). Additionally, the length between the proximal end of thin segment 130' and the distal tip of stylet 100' can be about 1.6 inches or less, e.g., about 0.6 to 1.4 inches (about 4 cm or less, e.g., about 1.5 to 3.5 cm), to provide desirable deflection mechanical characteristics.

[0023] A conductive coil 160 may be positioned around and fitted to the distal segment 136 of the core wire 120 to provide a passive sensor coil function for navigation. As shown in FIG. 4 (omitted from FIGS. 2 and 3 for clarity), a first lead 162 may be integrally coupled to the distal end of the conductive coil 160, wrapped (e.g., five times) around the core wire 120, and electrically coupled to a circuit board (not shown) within the housing member 102. Similarly, a second lead 164 may be integrally coupled to the proximal end of the conductive coil 160, wrapped (e.g., five times) around the core wire 120, and electrically coupled to a circuit board within the housing member 102. The conductive coil 160 and leads 162, 164 may each be conductive copper wire. In use, the conductive coil 160 is capable of picking up electromagnetic signals generated and transmitted by one or more drive coils (not shown) located outside the body. The combined signal of the conductive coil 160 may be transmitted via at least one of the leads 162, 164 to a circuit board within the housing member 102. The circuit board may transmit the signal to a computer (not shown) to indicate the location of the fifth portion 114. A further description of the structure and function of the conductive coil 160 and tip navigation system may be found in U.S. Pat. No. 10,098,567, the disclosure of which is incorporated by reference herein in its entirety.

[0024] The tubular body 140 may be fitted over the core wire 120, enclosing the conductive coil 160 and the leads 162, 164. The tubular body 140 may secure the leads 162, 164 and prevent them from loosening and / or coming into contact with fluids during insertion. The tubular body 140 may be made of a soft, flexible polymer (e.g., polyimide or nylon) that does not significantly affect or impact the bend profile of the stylet 100. The tubular body 140 may have an anti-friction coating or outer layer to reduce friction between the tubular body 140 and the catheter 150, facilitating removal of the stylet 100. For example, the tubular body 140 may have a polytetrafluoroethylene (PTFE) outer layer or a hydrophilic coating. The tubular body 140 may have a change in frictional properties along its length such that the distal portion of the tubular body 140 is more lubricious than the proximal portion of the tubular body 140. In some embodiments, the change in frictional properties may be provided by an increased surface texturing, with the distal portion of the tubular body being smoother and / or more textured, rough, or wavy than the proximal portion of the tubular body. The distal end of the tubular body 140 may be bonded to the core wire 120 distal to the conductive coil 160. For example, the distal end of the tubular body 140 may be bonded to the core wire 120 and / or sealed to the core wire with a cyanoacrylate adhesive to prevent fluids from entering the tubular body 140. In some embodiments, the tubular body 140 may have markings to allow visualization when the stylet 100 is sliding (intentionally or accidentally) relative to the catheter 150.

[0025] A distal tip 116 formed by the core wire 120 may extend distally from the distal end of the tubular body 140 and may be atraumatic (e.g., may have rounded and / or tapered edges) to reduce trauma to vascular tissue. The distal tip 116 may be exposed to ensure proper continuity of an electrocardiogram (ECG) signal to help confirm proper positioning within the SVC. The ECG signal may be further routed along the length of the core wire 120 to a circuit board (not shown) within the housing member 102. ECG continuity and position confirmation are further described in U.S. Pat. No. 10,321,890, the disclosure of which is incorporated by reference in its entirety.

[0026] FIG. 7 is an isometric view of the housing member 102. As shown, the housing member 102 may include first and second housing portions 180 and a nose member 182. The first and second housing portions 180 may be assembled to house electronic components (e.g., a circuit board) connected to the conductive coil 160 by leads 162, 164. For example, the first and second housing portions 180 may have corresponding pins and holes configured to be pressed together to form the housing member 102. Each of the first and second housing portions 180 may have interlocking grooves 188 on their sides to enhance a user's grip. Each of the first and second housing portions 180 may further include a protruding wall to be received in a neck or groove of the nose member 182 to secure the nose member 182 to the housing member 102 during assembly. Nose member 182 may comprise a sleeve having a lumen therethrough that receives elongate body 104 within housing member 102. Nose member 182 may have a tapered distal portion 184 extending distally from first and second housing portions 180 and a proximal portion received between first and second housing portions 180. Nose member 182 may be made of an elastomeric material (e.g., silicone rubber) that provides strain relief for attachment of elongate body 104 to housing 102.

[0027] 8A and 8B illustrate a stylet 100′ according to a second embodiment of the present invention. Stylet 100′ can have substantially the same features (incorporated herein, including stiffness profiles, and indicated by corresponding reference numerals unless otherwise specified) as described above with reference to stylet 100, including portions 110-116, 130, and 136 (corresponding portions 110′-116′, 130′, and 136′ are shown), and tubular body 140′. Thus, as described further herein, stylet 100′ can have preformed first and / or second bends α and β, although in some embodiments, stylet 100′ can have a preformed substantially straight configuration (omitting first and second bends α and β). In some embodiments, the stylet 100′ can have a proximal tapered section 132′ including a first tapered section 132a′ and a second tapered section 132b′, which are connected to one another but have different taper angles. The first tapered section 132a′ can be located proximal to the second tapered section 132b′ and can be a transition from the fourth section 112′. The first tapered section 132a′ can taper at a greater angle relative to the longitudinal axis than the second tapered section 132b′. If the second tapered section 132b′ has a more gradual angle at the proximal end of the thin segment 130′, some of the deflection occurring in the thin segment 130′ can contribute to the increased angle of the first tapered section 132a′. This reduces the abruptness of the transition. The increased angle of the first tapered portion 132a' provides a less abrupt transition, thereby allowing the overall length of the proximal tapered portion 132' to be shorter. The fifth portion 114' can include a distal segment 136' that receives a conductive coil 160' positioned distally of the first distal tapered portion 134' and a second distal tapered portion 138' located between the distal segment 136' and the distal tip 116'.Thus, the distal tip 116' may have substantially the same width or diameter as at least one of the proximal portions 106-112 (shown in the embodiment of FIG. 2). The thin segment 130' may have a constant width or diameter. The distal segment 136' may have a constant width or diameter that is larger than the thin segment 130' and smaller than the distal tip 116'. For example, the distal segment 136' may have a width or diameter of approximately 0.009 inches (approximately 0.22 mm), and the distal tip 116' may be larger and unground, having a width or diameter of approximately 0.011 inches (approximately 0.3 mm) to provide a larger surface area for ECG conduction.

[0028] As further shown in FIG. 8B, first tapered portion 132a' can have a first length (L1), second tapered portion 132b' can have a second length (L2), thin segment 130' can have a third length (L3), first distal tapered portion 134' can have a fourth length (L4), distal segment 136' can have a fifth length (L5), second distal tapered portion 138' can have a sixth length (L6), and distal tip 116' can have a seventh length (L7). The proximal tapered section 132′ (including the first and second tapered pair portions 132a′, 132b′) may be more gradual and have a length (L1+L2) greater than the lengths (L4, L6) and / or sum of the lengths of the first and / or second distal tapered sections 134′, 138′, thereby enabling the proximal tapered section 132′ to withstand greater forces during insertion while preventing stress risers / weak points that compromise the strength / performance of the stylet 100. The lengths of the first and second distal tapered sections 134′, 138′ may be shortened to allow the width of the stylet 100′ to increase distally over a short distance. For example, the proximal tapered portion 132' can be at least about twice the length of at least one (e.g., both) of the first and second distal tapered portions 134', 138' and less than about six times the length of at least one (e.g., the first distal tapered portion 134' alone) of the first and second distal tapered portions 134', 138'. In one exemplary embodiment, the first length (L1) can be about 0.1 to 0.3 inches, e.g., about 0.2 inches (about 2.5 to 7.5 mm, e.g., about 5 mm), the second length (L2) can be about 0.1 to 0.3 inches, e.g., about 0.2 inches (about 2.5 to 7.5 mm, e.g., about 5 mm), and the third length (L3) can be about 0.1 to 0.3 inches, e.g., about 0.2 inches (about 2.5 to 7.5 mm, e.g., about 5 mm).The fourth length (L4) may be about 0.1 to 0.2 inches, for example about 0.15 inches (about 2.5 to 5 mm, for example about 3.5 mm), the fifth length (L5) may be about 0.5 to 0.75 inches, for example about 0.635 inches (about 12.5 to 20 mm, for example about 16 mm), the sixth length (L6) may be about 0.005 to 0.015 inches, for example about 0.010 inches (about 0.125 to 0.4 mm, for example about 0.25 mm), and the seventh length (L7) may be about 0.05 to 0.15 inches, for example about 0.1 inches (about 1.25 to 4 mm, for example about 2.5 mm). Thus, the distance between the proximal end of the thin segment 130' and the distal end of the stylet 100' can be about 1.6 inches or less, e.g., about 0.6 to 1.4 inches (about 4 cm or less, e.g., about 1.5 to 3.5 cm), to provide desirable deflection mechanical characteristics. The stylet 100' can be made of a nickel-titanium alloy (Nitinol™) or stainless steel, and can have a polytetrafluoroethylene (PTFE) or hydrophobic coating. The stylet 100' can be without a navigation device (omitting the conductive coil 160, leads 162, 164, and tubular body 140), and can be used as a stiffening wire in conjunction with a separate navigation stylet (e.g., as shown in Figures 17-19) or by itself (e.g., assembled with a separate stylet-less PICC).

[0029] 9 illustrates a stylet 200 according to a third embodiment of the present invention. The stylet 200 can have substantially the same features (incorporated herein unless otherwise specified) as described above with reference to at least one of the stylets 100, 100′, including the stiffness profile indicated by corresponding reference numerals with respect to the stylet 100, and including portions 110-114, 130, and 136 (corresponding portions 210-214, 230, and 236 are shown), and proximal and distal tapered portions 132 and 134 (corresponding tapered portions 232 and 234 are shown). As described further herein, the stylet 200 can have preformed first and / or second bends α and β, although in some embodiments, the stylet 200 can have a preformed substantially straight configuration (omitting the first and second bends α and β). The stylet 200 can have an atraumatic shape, such as a large diameter distal tip 216 with a spherical weld 217 or rounded edges (e.g., as shown in FIGS. 10A and 10B ). The stylet 200 can be without a navigation device (omitting the conductive coil 160, leads 162, 164, and tubular body 140), and can be used as a stiffening wire in conjunction with a separate navigation stylet (e.g., as shown in FIGS. 17-19 ) or on its own (e.g., assembled with a separate stylet-less PICC).

[0030] 10A and 10B illustrate a stylet 200′ according to a fourth embodiment of the present invention. The stylet 200 can have substantially the same features (incorporated herein unless otherwise specified) as described above with reference to at least one of the stylets 100, 100′, and 200. As shown, the stylet 200′ can have, in longitudinal order, a proximal portion 201′ extending from a proximal end (not shown), a proximal tapered portion 232′, a narrow segment 230′, a distal tapered portion 234′, and a distal tip 216′ extending to the distal end. As further shown, the stylet 200′ can have a preformed, substantially straight configuration (omitting the first and second bends α and β), although in some embodiments, the stylet 200′ can have preformed first and / or second bends α and β as described further herein. The proximal portion 201′ may have a first width (or diameter), and a proximal taper 232′ may reduce the width of the stylet 200′ to a second width (or diameter) that is smaller than the first width at the thin segment 230′. A distal taper 234′ may extend from the thin segment 230′ and increase the width of the stylet 200′ to a third width (or diameter) at the distal tip 216′, where the first and third widths may be substantially identical. The second width of the thin segment 230′ may be smaller than the first and second widths to provide a flexible portion to allow deflection of the distal portion of the stylet 200′, for example, downwardly along the RBCV (as further described herein). Additionally, the third width of distal tip 216' may be large enough to allow distal tip 216' to be atraumatic and / or distal tip 216' may have a substantially cylindrical portion with a rounded and / or tapered periphery.

[0031] 10B, the proximal taper 232′ may have a first length (L1), the narrow segment 230′ may have a second length (L2), the distal taper 234′ may have a third length (L3), and the distal tip 216′ may have a fourth length (L4). The proximal taper 232′ may be more gradual, and the first length (L1) may be longer than the third length (L3), allowing the proximal taper 232′ to withstand greater forces during insertion while preventing stress risers / weak points that compromise the strength / performance of the stylet 200′. The third length (L3) of the distal taper 234′ may be shortened to allow the width of the stylet 200′ to increase over a short distance from the narrow segment 230′ to the distal tip 216′. For example, the proximal tapered portion 232' can be at least about twice the length of the distal tapered portion 234' and less than about six times the length of the distal tapered portion 234'. In one exemplary embodiment, the first length (L1) can be about 0.2 to 0.6 inches, e.g., about 0.4 inches (about 5 to 15 mm, e.g., about 10 mm), the second length (L2) can be about 0.6 to 1.0 inches, e.g., about 0.8 inches (about 15 to 25 mm, e.g., about 20 mm), the third length (L3) can be about 0.04 to 0.2 inches, e.g., about 0.08 inches (about 1 to 5 mm, e.g., about 2 mm), and the fourth length (L4) can be about 0.02 to 0.06 inches, e.g., about 0.04 inches (about 0.5 to 1.5 mm, e.g., about 1 mm). Thus, the fifth length (L2+L3+L4) between the proximal end of thin segment 230' and the distal tip of stylet 200' may be about 1.6 inches or less, e.g., about 0.6 to 1.4 inches (about 40 mm or less, e.g., about 15 to 35 mm) to provide desirable deflection mechanical characteristics. Stylet 200' may be made of a nickel-titanium alloy or stainless steel, and may have a polytetrafluoroethylene (PTFE) or hydrophobic coating.The stylet 200′ may be without a navigation device (omitting the conductive coil 160, the leads 162, 164, and the tubular body 140), and may be used as a stiffening wire in conjunction with a separate navigation stylet (e.g., as shown in Figures 17-19) or on its own (e.g., assembled with a separate stylet-less PICC).

[0032] 11A-12 illustrate a stylet 300 according to a fifth embodiment of the present invention. The stylet 300 can include a core wire 320, a tubular body 340, a conductive coil 360, and a magnetic hypotube 380. As shown, the core wire 320 can be received inside the magnetic hypotube 380, and the core wire 320 and magnetic hypotube 380 can be received within the tubular body 340. The stylet 300 can have substantially the same features (incorporated herein unless otherwise specified) as described above with respect to at least one of the stylets 100, 100′, and 200, including the body and tip curve profiles, sizes, and stiffness profiles for the stylet 100, portions 110-116, and 130, and the first and second bends α and β. The core wire 320 may be made of a nickel-titanium alloy, which is a kink-resistant alloy offering additional benefits, but is inherently non-magnetic. Therefore, to provide the desired characteristics of the present application (e.g., a navigation / electronic stylet with a curved profile and appropriate grinding profile), a magnetic hypotube 380 may be provided over the distal portion of the core wire 320. The magnetic hypotube 380 may be short and made of a magnetically permeable material, such as stainless steel or a similar material. The core wire 320 may have a tapered section 322 proximal to the magnetic hypotube 380, which may be proximal to the distal tip 326 of the core wire 320. A conductive coil 360 may be wrapped over the hypotube 380 to provide a passive sensor coil function for navigation, as described herein.

[0033] The core wire 320 and magnetic hypotube 380 may extend distally from the tubular body 340 and may be at least partially covered with conductive epoxy 382 at a portion of the stylet 300 distal to the tubular body 340. In some embodiments, the conductive epoxy 382 may secure the core wire 320, tubular body 340, and magnetic hypotube 380 together, and the conductive epoxy may be configured to direct ECG signals to the distal end portion 316. However, in some embodiments, a second epoxy (not shown) may bond the core wire 320 and magnetic hypotube 380, while the conductive epoxy 382 covers the distal end portion 316 to direct ECG signals. Additionally or alternatively, the core wire 320 and hypotube 380 may be welded together with sufficient exposed metal at the distal end portion 316 to direct ECG signals. Additionally or alternatively, a conductive hypotube (not shown) may be provided to direct ECG signals.

[0034] 13A and 13B illustrate a stylet 400 and catheter 450 according to a sixth embodiment of the present invention. The stylet 400 may have substantially the same features (incorporated herein unless otherwise specified) as described above with respect to at least one of the stylets 100, 100′, 200, and 300, including a core wire, a tubular body 440, and first and second bends α and β. The stylet 400 may further include an atraumatic distal segment 436 that reduces trauma to the posterior wall (BW) at the confluence (C) and facilitates deflection of the distal segment 436 down / away from the posterior wall (BW) toward the RBVC, compared to a stylet / PICC assembly that includes a leading tip disposed outwardly of the PICC alone (e.g., without an atraumatic distal segment). The distal segment 436 may be flexible and / or substantially compressible along the longitudinal axis of the stylet, and may extend distally of the distal end of the catheter 450 to initially contact the vein. For example, as shown in FIGS. 13A and 13B , the distal segment 436 may have a J-shape configured to resiliently deflect upon contact with the posterior wall (BW) and reduce "tent-like" behavior compared to a more pointed distal portion. A corewire may extend through the distal segment 436 such that the distal end 416 of the corewire extends proximally from the tubular body 440. The distal end 416 may be exposed to allow conduction of ECG signals, as further described herein. 14A-14C, a stylet 400′ received within a catheter 450′ can have a distal segment 436′ including multiple flexible members 436a′ (e.g., wires) having a curved or looped configuration that forms a basket. The flexible members 436a′ can extend distally from a tubular portion 436b′ and can be joined together at the distal tip of the stylet 400′ and / or looped back proximally to the tubular portion 436b′.The flexible member 436a′ may be elastically expandable (as shown in FIG. 14A ) and may collapse when pulled back into the catheter 450′ (as shown in FIG. 14B ). The flexible member 436a′ may direct ECG signals for navigation purposes, as described herein. Similar to the embodiment of FIGS. 13A and 13B , the distal segment 436′ may be elastically deflectable (as shown in FIG. 14C ) and reduce “tenting” when it contacts the posterior wall (BW) at the confluence (C). In yet another embodiment, the stylet 400″ received within the catheter 450″ may have a multi-member soft mesh distal segment 436″. The distal segment 436″ may be elastically deflectable and reduce “tenting” when it contacts the posterior wall (BW) at the confluence (C). Distal segment 436" may also conduct ECG signals as described herein. The functionality of distal segments 436, 436', 436" may complement or replace the functionality of first bend α and / or second bend β; thus, in some embodiments, first bend α and / or second bend β may be omitted, allowing stylet 400 to have a pre-formed straight configuration.

[0035] FIG. 16 illustrates a stylet 500 according to a seventh embodiment of the present invention. The stylet 500 may have substantially the same features (incorporated herein unless otherwise specified) as described above with respect to at least one of the stylets 100, 100′, 200, 300, and 400, including a core wire 520, a tubular body 540, a housing member 502, and first and second bends α and β. As shown, the distal end of the core wire 520 may be surrounded by the tubular body 540, thereby reducing trauma and enabling anti-friction contact with the posterior wall (BW) at the confluence (C). To allow ECG signal conduction, the tubular body 540 may include an opening 543 extending through the sidewall of the tubular body 540 between the proximal and distal ends of the tubular body 540. Opening 542 allows ECG signals from the body to pass through core wire 520. For example, opening 542 can be located distal to first and / or second bends α, β (e.g., at second bend β as shown) to locate the distal tip of stylet 500. Thus, core wire 520 can be configured to navigably direct ECG signals while avoiding potential trauma caused by the exposed, even sharp, distal tip of core wire 520.

[0036] 17-19 illustrate a pair of stylets 600, 601 according to an eighth embodiment of the present invention. The first stylet 600 can be configured to navigably guide ECG signals, and the second stylet 601 can be configured to shape the catheter 650 to facilitate passage through the SVC (unless otherwise specified), as further described herein with respect to at least one of the stylets 100, 100′, 200, 300, 400, and 500 and incorporated herein. The first stylet 600 can include a housing 602, a tubular body 640, a core wire disposed within the tubular body 640 and having a distal tip 616 for conducting ECG signals, and a conductive coil 660 disposed around the core wire within the tubular body 640, as further described herein with respect to at least one of the stylets 100, 100′, 200, 300, 400, and 500. The second stylet 601 may be a non-conductive elongated member or wire preformed with first and second bends α and β to facilitate passage of the catheter 650 past the confluence (C). As shown in the first assembly of FIG. 18, the first and second stylets 600, 601 may be inserted into separate lumens of the catheter 650. As further shown in the second assembly of FIG. 19, the first and second stylets 600, 601 may be inserted into the same lumen of the catheter 650. In either assembly, separating the functions (e.g., ECG navigation and catheter traversability) between the first and second stylets 600, 601 may facilitate manufacturing by, for example, allowing different materials with optimized mechanical and / or electrical properties to perform each function.

[0037] The many features and advantages of the present invention will be apparent from the detailed specification, and it is thus intended by the appended claims to cover all such features and advantages of the present invention which fall within the true spirit and scope of the invention. Further, because numerous modifications and changes will readily occur to those skilled in the art, it is not intended that the invention be limited to the exact construction and operation as illustrated and described, and therefore, all suitable modifications and equivalents may be employed which fall within the scope of the present invention.

Claims

1. 1. An assembly for accessing a patient's superior vena cava without visualizing the patient's vascular system, said assembly comprising: a stylet including a housing member and an elongate body configured to be inserted through the vascular system of the patient, the elongate body extending from the housing member to a distal tip and including a core wire disposed within a tubular body, the core wire having a preformed shape in a first state and a straightened shape in a second state, a potential energy of the core wire in the first state being less than a potential energy of the core wire in the second state, the core wire comprising: a first portion extending distally from the housing member and having a substantially straight shape in the first state; a second portion extending distally from the first portion and having a first preformed bend in the first condition; a third portion extending distally from the second portion and having a substantially straight shape in the first state; a fourth portion extending distally from the third portion and having a second preformed bend in the first condition; a fifth portion extending distally from the fourth portion to the distal tip, the fifth portion having a substantially straight shape in the first state, the fifth portion including a thin segment having a reduced width or diameter relative to the first through fourth portions, and a distal segment between the thin segment and the distal tip, the distal segment having a larger width or diameter than the thin segment, the thin segment configured to increase the flexibility of the distal tip, the distal tip having a larger width or diameter than the distal segment; a first distal tapered section having a width or diameter that increases distally, the first distal tapered section being disposed between the narrow segment and the distal segment; a second distal tapered section having a width or diameter that increases distally, the second distal tapered section being disposed between the distal segment and the distal tip; the first preformed bend and the second preformed bend are in the same plane and in the same direction; the first preformed bend defines a first angle between a longitudinal axis of the first section and a longitudinal axis of the third section in a range of 55 to 70 degrees on an inner side of a first arc length of the first preformed bend; the second preformed bend defines a second angle between the longitudinal axis of the third section and the longitudinal axis of the fifth section in a range of 8 to 15 degrees on the inner side of a second arc length of the second preformed bend; The assembly wherein the first arc length of the first preformed bend is between 3 and 7 inches (7.5 and 17.5 cm).

2. 2. The assembly of claim 1, wherein the second arc length of the second preformed bend is between 0.2 and 0.5 inches (0.5 and 1.3 cm).

3. 2. The assembly of claim 1, wherein the first and second preformed bends are configured to automatically align the distal tip at an approach angle toward a lower portion of the posterior wall of the vasculature to assist in directing the distal tip downward toward the superior vena cava during insertion of the stylet into the vasculature.

4. The assembly of claim 1 , wherein the core wire has minimal or no torque.

5. The assembly of claim 1 , wherein the thin segments are straight and have a constant width or diameter.

6. The assembly of claim 5 , wherein the narrow segment of the fifth portion includes a proximal end having a proximal taper that reduces in width or diameter distally.

7. The assembly of claim 6 , wherein the narrow segment of the fifth portion includes a distal end having the first distal tapered portion of increased width or diameter.

8. The assembly of claim 5 , wherein the thin segments have rounded and / or flattened cross sections.

9. The assembly of claim 1 , further comprising a conductive coil fitted to the core wire around the distal segment of the core wire to provide a passive sensor coil function for navigation.

10. The assembly of claim 9 , wherein the tubular body surrounds the conductive coil.

11. The assembly of claim 10 , wherein a distal end of the tubular body is coupled to the core wire distal to the conductive coil.

12. The assembly of claim 1 , wherein the distal tip has a greater width or diameter than the distal segment.

13. 2. The assembly of claim 1, wherein the core wire conducts electrocardiogram (ECG) signals, and the distal tip of the core wire extends distally of the tubular body, or the tubular body has an opening in a sidewall to allow fluid contact with the core wire.

14. The assembly of claim 1 , further comprising a conductive coil fitted around and to said core wire to provide a passive sensor coil function for navigation.

15. The assembly of claim 14 , wherein the tubular body surrounds the conductive coil.

16. The assembly of claim 15 , wherein a distal end of the tubular body is coupled to the core wire distal to the conductive coil.

17. 15. The assembly of claim 14, wherein the core wire conducts electrocardiogram (ECG) signals, and the distal tip of the core wire extends distally of the tubular body, or the tubular body has an opening in a sidewall to allow fluid contact with the core wire.

18. The assembly of claim 1 , wherein the core wire is comprised of a nickel-titanium alloy.

19. 2. The assembly of claim 1, wherein the first angle formed on an inward side of the first arc length of the first preformed bend is 60 degrees between a longitudinal axis of the first portion and a longitudinal axis of the third portion.

20. 2. The assembly of claim 1, wherein the second angle formed on an inner side of the second arc length of the second preformed bend is 10 degrees between a longitudinal axis of the third portion and a longitudinal axis of the fifth portion.

21. The assembly of claim 1 , wherein a portion of the core wire is bonded to a portion of the tubular body.

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