Stylet with improved insertion ease

Abstract

There is a need to improve one or more features regarding the insertability of the stylet, or more specifically, the stylet that should be assembled with the PICC. [Solution] A low-torque or non-torque stylet is preferable to have a core wire, the core wire having a first preformed bend at a first angle of about 15 to 90° and a second preformed bend at a second angle of about 8 to 15°, the second preformed bend being located distal to the first preformed bend, the first preformed bend being longer than the second preformed bend, the core wire further having an intermediate portion extending between the first preformed bend and the second preformed bend and a distal portion extending between the second preformed bend and the distal tip, the distal portion having a segment having a reduced width or reduced diameter that increases the degree of deflection of the distal tip, and further having a navigation device.

Description

Technical Field

[0001] The present disclosure, i.e., the present invention, generally relates to a stiffening wire or stylet for placing a vascular catheter, particularly a low torque or non-torque stiffening wire or stylet with improved insertability.

[0002]

Reference to Related Applications

Background Art

[0003] A PICC (Peripherally Inserted Central Venous Catheter) is a catheter to be inserted into a vein in the upper arm and passed through to the superior vena cava (SVC). A PICC generally enables access to a thick central vein near the heart for administering drugs or liquid nutrients. A PICC can help avoid the pain of frequent needle punctures and reduce the risk of irritation to the thin veins in the arm.

[0004] The inventors recognize the need to improve one or more features of the insertability of the stylet, more specifically, the stylet to be assembled with the PICC. PICCs are often inserted at the bedside without the use of advanced equipment for visualizing anatomical structures. While several novel devices are available that display the position of the PICC on a monitor, these devices only provide an approximate reference for the placement of the tip relative to external devices. The distal tip of the stylet still often fails to advance forward because it hits the wall of the vascular system before sharp curves or bends, and instead travels along other branches of veins that are not in the intended insertion path to the SVC, for example, and / or contacts the vein wall and loops back. As a result, it may take several attempts before the PICC is properly inserted into the SVC, or the user may not be able to position the PICC correctly at all. The patient may then need to be moved to another location in the hospital, for the purpose of visualizing the anatomical structure with more advanced equipment for inserting the PICC into its final location. The disclosed invention addresses one or more of these and / or other drawbacks of the prior art. [Overview of the Initiative]

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

[0006] In some embodiments, the first angle is approximately 15–90° with respect 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° with respect 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, as a whole, are located within 10 inches (25 cm) of the distal tip end of the core wire. In some embodiments, the first angle is approximately 60° with respect to the longitudinal axis of the stylet, and the second angle is approximately 10° with respect 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 and second preformed bends are located in the same plane. 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 greater width or diameter than the thin segment. In some embodiments, the distal tip has a greater 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 portion includes a first tapered portion and a second tapered portion, the first tapered portion being tapered at a larger angle than the second tapered portion. In some embodiments, the stylet further comprises a tubular body fitted onto a core wire. In some embodiments, the distal end of the core wire extends distally to the tubular body, and the distal end transmits electrocardiogram (ECG) signals. In some embodiments, the tubular body has openings in its side walls that allow fluid contact with the core wire.In some embodiments, the stylet further comprises a navigation device fitted over the core wire while being housed within a tubular body. In some embodiments, the navigation device consists of a conductive coil. In some embodiments, the torque of the stylet is minimal or zero. In some embodiments, the core wire further comprises an intermediate portion of about 1 to 3 inches (2.5 to 7.5 cm) extending between a first preformed bend and a second preformed bend. In some embodiments, the core wire further comprises a distal portion with a thin segment, the distal portion extending about 1 to 2 inches (2.5 to 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 is made of a nickel-titanium alloy. In some embodiments, the distal tip is formed of one of a J-shaped section, a basket, or a mesh. In some embodiments, the stylet is a component of an assembly that includes a second stylet for transmitting ECG signals. In some embodiments, the stylet is a component of an assembly that includes a catheter.

[0007] A second aspect of the present invention is a low or non-torque stylet comprising a core wire, the core wire comprising a first preformed bend at a first angle of about 15 to 90° and a second preformed bend at a second angle of about 8 to 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 comprising an intermediate portion of about 1 to 3 inches (2.5 to 7.5 cm) extending between the first and second preformed bends, and the second preformed bend and distal tip portion The present invention relates to a low or non-torque stylet, further comprising a distal portion of approximately 1 to 2 inches (2.5 to 5 cm) located between the end and the distal portion having a narrow segment having a reduced width or reduced diameter that increases the degree of deflection of the distal tip, the first preformed bend and the second preformed bend are located collectively within 10 inches (25 cm) from the end of the distal tip of the core wire, and the stylet further comprises a navigation device provided around the core wire and a tubular body provided around the core wire and the navigation device.

[0008] A third aspect of the present invention relates to a stylet having a thin segment, a proximal tapered portion located proximal to the thin segment, and a distal portion including 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, the first tapered portion tapering at a larger 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 tapered portion. In some embodiments, the length of the thin segment is longer than the length of the proximal tapered portion. In some embodiments, the thin segment has a certain 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 a rounded and / or tapered edge. In some embodiments, the stylet has a preformed straight form. In some embodiments, the stylet has a preformed curved form.

[0009] To facilitate understanding of the present invention, various aspects of the invention are illustrated in the accompanying drawings. [Brief explanation of the drawing]

[0010] [Figure 1]This is a diagram showing the vascular system of the human body. [Figure 2] This is a perspective view of a first embodiment of the stylet according to the present invention. [Figure 3] Figure 2 is a side view of the distal portion of the stylet. [Figure 4] Figures 2 and 3 are perspective views of the core wire and distal portion of the tubular body of the stylet. [Figure 5] Figures 2 to 4 are side views of the core wire and distal portion of the tubular body of the stylet. [Figure 6] Figure 1 shows the distal portion of the stylet shown in Figures 2-5 within a catheter inserted into the vascular system of the human body. [Figure 7] Figures 1 to 6 are isometric views of the housing components of the stylet. [Figure 8A] This is a diagram of a second embodiment of the stylet according to the present invention. [Figure 8B] This is a diagram of a second embodiment of the stylet according to the present invention. [Figure 9] This is a side view of a third embodiment of the stylet according to the present invention. [Figure 10A] This is a diagram of a fourth embodiment of the stylet according to the present invention. [Figure 10B] This is a diagram of a fourth embodiment of the stylet according to the present invention. [Figure 11A] This is a diagram of a fifth embodiment of the stylet according to the present invention. [Figure 11B] This is a diagram of a fifth embodiment of the stylet according to the present invention. [Figure 12] Figures 11A and 11B are side views of the stylet. [Figure 13A] This is an isometric view of a sixth embodiment of a stylet located within a catheter according to the present invention. [Figure 13B] Figure 13A shows the distal end of the stylet and catheter. [Figure 14A] Figures 13A and 13B show the first modified example of the stylet. [Figure 14B]FIG. 13A and FIG. 13B are diagrams showing a first modification of the stylet. [Figure 14C] FIG. 13A and FIG. 13B are diagrams showing a first modification of the stylet. [Figure 15] FIG. 13A and FIG. 13B are diagrams showing a second modification of the stylet. [Figure 16] FIG. 13A and FIG. 13B are diagrams showing a second modification of the stylet. [Figure 17] FIG. 13A and FIG. 13B are diagrams showing a second modification of the stylet. [Figure 18] FIG. 13A and FIG. 13B are diagrams showing a second modification of the stylet. [Figure 19] FIG. 13A and FIG. 13B are diagrams showing a second modification of the stylet. DETAILED DESCRIPTION OF THE INVENTION

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

[0012] The present invention generally relates to a stylet that provides a particular combination of bends and / or stiffness profiles that can consistently pass a catheter through an anatomical curve of the vasculature into a desired location within the vasculature. The stylet of the present invention preferably is low or non-torqueing, such that a user can pass the stylet without knowing the orientation of the distal tip (i.e., the direction the tip is facing, "up" or "down") or controlling the orientation of the distal tip by turning the proximal end of the stylet. More specifically, the stylet can consistently provide a desired approach angle through the vasculature (e.g., at the confluence of the internal jugular vein, brachiocephalic vein, and / or subclavian vein) to a desired location. This approach angle can be considered desirable regardless of how the user inserts the catheter into the vasculature and / or turns the proximal end of the catheter during insertion. The stylet preferably further has a thin segment that is softer or more flexible than other portions of the stylet. The thin segment being flexible promotes deflection of the distal tip when contacting the vein wall and can reduce trauma to the vein. Further, the thin segment can improve the contact angle of the distal tip by arching upward when the distal tip contacts the vein wall, such that the distal tip will face downward in a desired direction. As a commercial advantage, there are fewer attempts at insertion, a shorter insertion time, and less user frustration during insertion.

[0013] Figure 1 is a reference anatomical diagram including the vascular system of potential pathways, through which a stylet combined with a catheter (e.g., a peripherally punctured central venous catheter, PICC) can be passed into the superior vena cava (SVC) according to the present invention. The stylet / PICC can enter the vascular system at the location of several different veins (e.g., ulnar cephalic vein, brachial vein, radial cephalic vein). The vascular system can be approached at the optimal vein location by needle puncture, an approach wire can be passed through the needle and inserted into the vascular system, and the sheath can be guided along the approach wire after the needle is withdrawn. After the approach wire is withdrawn from the sheath, the stylet / PICC can be passed through the sheath that entered the vascular system at the location of a significant vein into the subclavian vein (SUB), and through that into the brachiocephalic vein (BCV, e.g., right brachiocephalic vein, RBCV), and through that finally into the SVC. The most common area where insertion is difficult is the confluence (C) where the SUB terminates and joins the internal jugular vein (IJ) and the BCV, as further shown in Figure 6. Confluence (C) typically includes the sharpest curve in the anatomical pathway, which can define a 90° curve or drop. Due to this sharp curve, the catheter may deviate in the wrong direction (e.g., ascend along the IJ) or become trapped and unable to advance at all. While Figure 1 and its corresponding description relate to the insertion of a stylet from the SUB into the RBCV, the stylet of the present invention can be inserted via other pathways, including via the left brachiocephalic vein (LBCV).

[0014] Figure 2 is an isometric view of the stylet 100 according to the present invention, and Figure 3 is a side view of the distal end of the stylet 100. As shown in the figures, the stylet 100 preferably has a housing member 102 located at the proximal end of an elongated body 104 configured to be inserted into the vascular system. The elongated body 104 preferably has a core wire 120 and a tubular body 140 provided around the core wire 120, as shown in Figures 4 to 6.

[0015] The core wire 120 may have a nominal or preformed shape as shown in Figures 2 and 3, such a shape may include a preformed first curved or bent portion α ("body bend"). During insertion, the first bend α may be elastically forced to straighten due to the anatomical insertion path, which is straighter than the preformed core wire. When straightened, the core wire 120 enters a state of high potential energy and attempts to compress back to a state of low potential energy, similar to how a stretched spring attempts to return to its original unstressed state. When the distal tip 116 reaches the confluence (C), the lowest potential energy state of the first bend α causes the distal tip 116 to bend downward toward the SVC. The nominal shape and stiffness of the elongated body 104 may be achieved by the preformed shape and stiffness of the core wire 120. As shown in the figure, the core wire 120 (and elongated body 104) is preferably substantially straight in its nominal state and has a first portion 106 extending distally from the housing member 102. The core wire 120 (and elongated body 104) is preferably having a preformed first curved or bent portion α and a second portion 108 extending distally from the first portion 106. The core wire 120 (and elongated body 104) is preferably substantially straight in its nominal state and has a third portion (or intermediate portion) 110 extending distally from the second portion 108. The core wire 120 (and elongated body 104) is preferably having a preformed second curved or bent portion β and a fourth portion 112 extending distally from the third portion 110. The core wire 120 (and the elongated body 104) is preferably substantially straight in its nominal state and has a fifth portion (or distal portion) 114 that extends distally from the fourth portion 112 to the distal tip portion 116. Thus, the first bend α is preferably located proximal to the second bend β, and is preferably separated by only the third portion 110.As further shown in Figure 3, the first bend α may define a first angle of about 15 to 90° (e.g., 55 to 70°) between the respective longitudinal axes of the first portion 106 and the third portion 110, and thus the first bend α can define a supplemental arc of about 90 to 165° (as shown in Figure 3) (however, unless otherwise specified, the angle of the first bend α is defined herein between the respective longitudinal axes of the first and third portions 106, 110). The second bend β is preferably set to a second angle of about 8 to 15° between the longitudinal axes of the third portion 110 and the fifth portion 114, so that the second bend β can set to a supplemental arc of about 165 to 172° (shown in Figure 3) (however, unless otherwise specified, the angle of the second bend β is set in this specification between the longitudinal axes of the third and fifth portions 110 and 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 provided around the stylet 100. In other words, the catheter 150 is preferably nominally straight and has some stiffness, so that it can straighten the stylet 100 at the first bend α and the second bend β. The stiffness of the catheter 150 is determined by the brand, material, lumen, and size. In the case of a rigid catheter 150, the stylet 100 is preferably curved to provide an appropriate angle with respect to the vascular system. Thus, it is preferably designed to provide an assembly of the stylet 100 and the catheter 150 having a first portion at the first bend α with an angle of 5-80° and a second portion at the second bend β with an angle of 3-10°, where each of these angles is with respect to the longitudinal axis of the assembly. Thus, the assembly of the stylet 100 and catheter 150 has an angle greater than the anatomical reference curvature.

[0016] The second section 108 preferably has an arc length of about 3 to 7 inches (about 7.5 to 17.5 cm), for example, about 5.3 inches (about 13.5 cm); the third section 110 preferably has a length of about 0 to 3 inches (about 0 to 7.5 cm); the fourth section 112 preferably has an arc length of about 0.2 to 0.5 inches (about 0.5 to 1.25 cm); and the fifth section 114 preferably has a length of about 1 to 2 inches (about 2.5 to 5 cm). Thus, in a preferred embodiment for inserting the PICC, the first curve α preferably is a gradual curve forming a first angle of about 60°, starting about 3 inches (about 7.5 cm) from the end of the distal tip section 116 and extending proximal to about 8.3 inches (about 21 cm) from the end of the distal tip section 116. The second bend β is preferably formed by bending the stylet 100 around a pin with a diameter of approximately 0.25 inches (approximately 0.5 cm) located approximately 1.25 inches (approximately 3 cm) from the end of the distal tip 116, thereby creating a second angle of approximately 10° with an arc length of approximately 0.22 inches (approximately 0.5 cm).

[0017] Therefore, it is preferable that the first angle of the first curve α (located between the first section 106 and the third section 110) is substantially larger than the second angle of the second curve β (located between the third section 110 and the fifth section 114). For example, it is preferable that the difference between the first angle of the first curve α and the second angle of the second curve β is at least 40°. Furthermore, it is preferable that the arc length of the second section 108 (and the first curve α) is substantially longer than the arc length of the fourth section 112 (and the second curve β). For example, the difference between the arc length of the second section 108 (and the first curve α) and the arc length of the fourth section 112 (and the second curve β) is preferably at least 4 inches (about 10 cm), and the first curve α and the second curve β as a whole are preferably located within 10 inches (25 cm) of the distal tip 116. Thus, the second curve β is preferably located in proximity to the distal tip 116 such that, when the distal tip 116 is located at the confluence (C), the second curve β is located in the region of a reference anatomical structure having some curvature (upstream of the insertion site / towards the insertion site).

[0018] The first curved portion α preferably corresponds to the curved portion (curve) of the main body, and the second curved portion β preferably corresponds to the curve of the tip, and the first and second curved portions α and β preferably lie in the same plane and in the same direction (in order to prevent reaction between the curved portions α and β). The first curved portion α preferably is configured to orient the stylet 100 into the anatomical structure, and the second curved portion β preferably is configured so that when the first curved portion α is orienting, the distal tip 116 can approach the location of the difficult curved portion of the anatomical structure at a desirable angle. Thus, the first and second curved portions α and β can enhance the user's ability to pass the stylet 100 to the desired position without visualizing the vein or steering the stylet 100. For example, as shown in Figure 6, the first and second bends α and β are preferably configured to automatically maintain an approach angle that directs the distal tip 116 toward the lower portion of the posterior wall (BW) of the vascular system, thereby increasing the likelihood that the distal tip 116 will be directed downward toward the spondylovascular cavity (SVC). In addition, 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 arching in a predictable direction and returning to a loop shape or "tent shape." Furthermore, when the distal tip 116 strikes at the desired angle, it can strike the posterior wall (BW) of the vein obliquely and advance straight downward along the RBVC, in which case the user does not experience excessive resistance and thus reduces trauma to the posterior wall (BW).

[0019] The stylet 100 is preferable to be self-directing in that the manual rotation of the proximal housing member 102 does not substantially transmit enough torque to the distal tip 116 to produce a consistent rotation. Thus, the core wire 120 is preferable to be low-torque or non-torque. For example, the user may rotate the proximal housing member 102 many times, after which a considerably large rotational motion is transmitted to the distal tip 116, which can then rotate completely and quickly axially and return to the desired position.

[0020] Thus, the first curved section α is preferably configured to automatically align with the curvature of the vascular system during insertion of the stylet 100, for the purpose of causing the distal tip 116 to point "downward" during RBVC, since the first and second curved sections α and β are in the same plane and direction. The distal tip 116 can always point downward, for example, when entering a vascular junction (C) where it is most difficult for the PICC to navigate through a tight curvature. The stylet 100 is preferably non-torque and non-steering, thereby eliminating user control of the orientation of the distal tip 116, and the stylet 100 can automatically find the correct orientation in the vascular system regardless of the initial insertion orientation and / or how the stylet 100 is rotated during insertion. Furthermore, in some embodiments, the stylet 100 is provided at the proximal end of the core wire 120 and preferably has a torque limiting member (e.g., a torque limiting grinding section) that further reduces the user's ability to transmit torque.

[0021] As further shown in Figures 4-6, the fifth section 114 (including the distal tip 116) preferably has 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 it to flex when it contacts the vein wall without causing vascular trauma. Furthermore, the thin segment 130 can improve the contact angle of the distal tip 116 by causing it to arch upward when it contacts the vein wall, resulting in the distal tip 116 pointing downward toward the RBCV. The thin segment 130 preferably is straight and has a consistent width or diameter. The fifth section 114 preferably is short in length to provide desirable flexural kinematic features. 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 affects the stylet 100 after assembly, and the stylet 100 does not bend too easily during insertion. Thus, the stylet 100 has a stiffness profile such that the thin segment 130 of the fifth portion 114 is the first point along the length of the core wire 120 to bend, thereby improving the insertion angle of the distal tip 116 and maintaining the pushability of the assembly. If the proximal portions 106-112 of the core wire 120 bend before the thin segment 130 of the fifth portion 114, the longitudinal pushing force applied by the user is no longer 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, and this thin segment may be formed by a proximal tapered section 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 tapered section 134 located at the distal end that increases the width or diameter of the stylet 100 up to the distal segment 136. The thin segment 130 may have a rounded and / or flattened cross-section. Thus, the distal tapered section 134 may connect the thin segment 130 to the distal segment 136, which is coupled to the distal tip section 116. In some embodiments, the distal segment 136 and the distal tip section 116 may have a width or diameter 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 remaining portion of the core wire 120). For example, sections 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 the thin segment 130 may have a width or diameter of approximately 0.004 inches (approximately 0.1 mm). The proximal tapered section 132 may have a longer length and a gentler slope than the distal tapered section 134, thereby enabling the proximal tapered section 132 to withstand greater forces during insertion and preventing the formation of stress concentration points / weak points that would impair the strength / performance of the stylet 100. For example, the proximal tapered portion 132 is preferably at least about twice the length of the distal tapered portion 134 and less than about six times the length of the distal tapered portion 134 (for example, at least three, four, or five times the length of the distal tapered portion 134). Furthermore, the length between the proximal end of the thin segment 130' and the distal tip of the stylet 100' is preferably about 1.6 inches or less, for example about 0.6 to 1.4 inches (about 4 cm or less, for example about 1.5 to 3.5 cm) to provide desirable bending kinematic characteristics.

[0023] Preferably, the conductive coil 160 is fitted onto the core wire 120, positioned around its distal segment 136, so as to provide a passive sensor coil function for navigation. Preferably, as shown in Figure 4 (omitted in Figures 2 and 3 for clarity), a first lead wire 162 is integrally coupled to the distal end of the conductive coil 160, wound around the core wire 120 (e.g., five times), and electrically coupled to a circuit board (not shown) within the housing member 102. Similarly, a second lead wire 164 is integrally coupled to the proximal end of the conductive coil 160, wound around the core wire 120 (e.g., five times), and electrically coupled to a circuit board within the housing member 102. Preferably, the conductive coil 160 and the lead wires 162 and 164 are conductive copper wires. For use, the conductive coil 160 can pick up electromagnetic signals generated and transmitted by one or more drive coils (not shown) located outside the body. Preferably, the combined signal from the conductive coil 160 is transmitted to a circuit board in the housing member 102 via at least one of the lead wires 162, 164. The circuit board preferably transmits this signal to a computer (not shown) to indicate the location of the fifth section 114. A further description of the structure and function of the conductive coil 160 and the tip navigation system can be found in U.S. Patent No. 10,098,567, which is incorporated herein by reference and whose entire disclosure is part of this specification.

[0024] The tubular body 140 is preferably fitted onto the core wire 120 while enclosing the conductive coil 160 and lead wires 162, 164. The tubular body 140 can fix the lead wires 162, 164 and prevent them from becoming loose or / or coming into contact with fluid during insertion. The tubular body 140 is preferably made of a soft and flexible polymer (e.g., polyimide or nylon) that does not exert a large effect or impact on the curved profile of the stylet 100. The tubular body 140 is preferably having an anti-friction coating or outer layer to reduce the frictional force acting between it and the catheter 150 in order to facilitate the removal of the stylet 100. For example, the tubular body 140 is preferably having a polytetrafluoroethylene (PTFE) outer layer or a hydrophilic coating. The tubular body 140 preferably has a change in frictional properties along its length such that the distal portion of the tubular body 140 is more abrasive than the proximal portion of the tubular body 140. In some embodiments, the change in frictional properties is preferably provided by an increase in surface texture, and the distal portion of the tubular body is preferably smoother than the proximal portion and / or has a higher texture, is rougher, or wavy. The distal end of the tubular body 140 is preferably coupled to the core wire 120 on the distal side of the conductive coil 160. For example, the distal end of the tubular body 140 is preferably coupled to the core wire 120 and / or sealed to the core wire with a cyanoacrylate adhesive to prevent fluid from entering the tubular body 140. In some embodiments, the tubular body 140 may have markings to make it visible when the stylet 100 is sliding against the catheter 150 (whether intentionally or accidentally).

[0025] The distal tip 116 formed by the core wire 120 is preferably extending distally from the distal end of the tubular body 140, and this distal tip 116 is preferably intact to reduce trauma to vascular tissue (for example, it is preferably rounded and / or has a tapered edge). The distal tip 116 is preferably exposed to ensure adequate conduction of an electrocardiogram (ECG) signal to help confirm proper positioning within the SVC. The ECG signal is preferably further guided along the length of the core wire 120 to a circuit board (not shown) in the housing member 102. ECG conduction and positioning are further described in U.S. Patent No. 10,321,890, which is incorporated herein by reference and whose entire disclosure is part of this specification.

[0026] Figure 7 is an isometric view of the housing member 102. As shown, the housing member 102 preferably has first and second housing portions 180 and a nose member 182. The first and second housing portions 180 preferably are assembled to house electronic components (e.g., circuit boards) connected to the conductive coil 160 by lead wires 162, 164. For example, the first and second housing portions 180 preferably have corresponding pins and holes configured to press against each other to form the housing member 102. Each of the first and second housing portions 180 preferably has grooves 188 on its side that connect to each other to enhance the user's grip. Each of the first and second housing portions 180 preferably further has a protruding wall to be received in the neck or groove of the nose member 182 to secure the nose member 182 to the housing member 102 during assembly. The nose member 182 preferably has a sleeve through which a lumen passes, allowing the elongated body 104 to be received into the housing member 102. The nose member 182 preferably has a tapered distal portion 184 extending distally from the first and second housing portions 180 and a proximal portion that is received between the first housing portion 180 and the second housing portion 180. The nose member 182 preferably is made of an elastomer material (e.g., silicone rubber) that provides strain relief for attaching the elongated body 104 to the housing 102.

[0027] Figures 8A and 8B show a stylet 100' according to a second embodiment of the present invention. The stylet 100' preferably has substantially the same features as those described above with reference to stylet 100 (which, unless otherwise specified, are incorporated herein, including stiffness profiles and indicated by corresponding reference numerals), such features include portions 110-116, 130, 136 (corresponding portions 110'-116', 130', 136' are shown), and a tubular body 140'. Thus, as will be further described herein, the stylet 100' preferably has preformed first and / or second curves α,β, although in some embodiments the stylet 100' may have a preformed substantially straight form (without the first and second curves α,β). In some embodiments, the stylet 100' may have a proximal tapered portion 132' including a first tapered portion 132a' and a second tapered portion 132b', where these tapered portions 132a' and 132b' are connected to each other but have different taper angles. The first tapered portion 132a' may be located proximal to the second tapered portion 132b' and may be a transition from a fourth portion 112'. The first tapered portion 132a' may be tapered at a larger angle with respect to the longitudinal axis than the second tapered portion 132b'. If the second tapered portion 132b' has a gentler angle at the proximal end of the thin segment 130', a portion of the deflection occurring in the thin segment 130' contributes to increasing the angle of the first tapered portion 132a'. This reduces the steepness of the transition. The large angle of the first tapered portion 132a' results in a transition with less steepness, thereby shortening the overall length of the proximal tapered portion 132'. The fifth portion 114' preferably has a distal segment 136' that receives a conductive coil 160' positioned distal to the first distal tapered portion 134', and a second distal tapered portion 138' located between the distal segment 136' and the distal tip portion 116'.Thus, the distal tip portion 116' is preferably substantially the same width or diameter as at least one of the proximal portions 106-112 (shown in the embodiment of Figure 2). The thin segment 130' is preferably a constant width or diameter. The distal segment 136' is preferably a constant width or diameter that is larger than the thin segment 130' and smaller than the distal tip portion 116'. For example, the distal segment 136' is preferably about 0.009 inches (about 0.22 mm) in width or diameter, the distal tip portion 116' is preferably larger than this and in an unground state, and this distal tip portion is preferably about 0.011 inches (about 0.3 mm) in width or diameter to increase the surface area for ECG conductivity.

[0028] As further shown in Figure 8B, the first tapered portion 132a' may have a first length (L1), the second tapered portion 132b' may have a second length (L2), the narrow segment 130' may have a third length (L3), the first distal tapered portion 134 prime may have a fourth length (L4), the distal segment 136' may have a fifth length (L5), the second distal tapered portion 138' may have a sixth length (L6), and the distal tip portion 116' may have a seventh length (L7). The proximal tapered portion 132' (including the first and second tapered pair portions 132a', 132b') is preferably more gradual and has a length (L1+L2) longer than the lengths (L4, L6) of the first and / or second distal tapered portions 134', 138' and / or the sum of these lengths, thereby enabling the proximal tapered portion 132' to withstand large forces during insertion and preventing the formation of stress concentration points / weak points that would impair the strength / performance of the stylet 100. The lengths of the first and second distal tapered portions 134', 138' are preferably shortened so that the width of the stylet 100' can increase distally over a short distance. For example, the proximal tapered portion 132' is preferably 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., only the first distal tapered portion 134') of the first and second distal tapered portions 134', 138'. In one exemplary embodiment, the first length (L1) is preferably about 0.1 to 0.3 inches, for example about 0.2 inches (about 2.5 to 7.5 mm, for example about 5 mm), the second length (L2) is preferably about 0.1 to 0.3 inches, for example about 0.2 inches (about 2.5 to 7.5 mm, for example about 5 mm), and the third length (L3) is preferably about 0.1 to 0.3 inches, for example about 0.2 inches (about 2.5 to 7.5 mm, for example about 5 mm).The fourth length (L4) is preferably 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) is preferably 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) is preferably 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) is preferably 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′ is preferably about 1.6 inches or less, for example about 0.6 to 1.4 inches (about 4 cm or less, for example about 1.5 to 3.5 cm), to provide desirable bending kinematic characteristics. The stylet 100′ is preferably made of nickel-titanium alloy (Nitinol™) or stainless steel, and this stylet is preferably coated with polytetrafluoroethylene (PTFE) or a hydrophobic coating. The stylet 100′ is preferably without a navigation device (excluding the conductive coil 160, lead wires 162, 164, and tubular body 140), and this stylet may be used in conjunction with a separate navigation stylet (e.g., shown in Figures 17 to 19) or by itself (e.g., assembled with a PICC without another stylet) as a stiffening wire.

[0029] Figure 9 shows a stylet 200 according to a third embodiment of the present invention. The stylet 200 may have substantially the same features as described above with reference to at least one of the stylets 100, 100' (which are incorporated herein by reference unless otherwise specified), such features include a stiffness profile indicated by the corresponding reference numerals with respect to stylet 100, and portions 110-114, 130, 136 (corresponding portions 210-214, 230, 236 are shown) and proximal and distal tapered portions 132, 134 (corresponding tapered portions 232, 234 are shown). As will be further described herein, the stylet 200 may have preformed first and / or second curves α, β, but in some embodiments the stylet 200 may have a preformed substantially straight form (without the first and second curves α, β). The stylet 200 may have a distal tip 216 with a large diameter and an intact shape, such as a spherical weld 217 or a rounded edge (for example, shown in Figures 10A and 10B). The stylet 200 may be without a navigation device (excluding the conductive coil 160, lead wires 162, 164, and tubular body 140), and may be used as a stiffening wire either in conjunction with a separate navigation stylet (for example, shown in Figures 17-19) or by itself (for example, assembled with a PICC without another stylet).

[0030] Figures 10A and 10B show a stylet 200' according to a fourth embodiment of the present invention. The stylet 200 preferably has substantially the same features as described above with reference to at least one of the stylets 100, 100', and 200 (as incorporated herein unless otherwise specified). As shown, the stylet 200' preferably has, in its 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 portion 216' extending to the distal end. As further shown, the stylet 200' preferably has a preformed substantially straight form (without the first and second curves α,β), although in some embodiments the stylet 200' may have preformed first and / or second curves α,β as further described herein. The proximal portion 201' may have a first width (or diameter), and the proximal tapered portion 232' may reduce the width of the stylet 200' to a second width (or diameter) smaller than the first width at the narrower segment 230'. The distal tapered portion 234' may extend from the narrower 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 the same. The second width of the narrower segment 230' may be smaller than the first and second widths to provide a flexible portion that allows for, for example, downward bending of the distal portion of the stylet 200' along the RBCV (as further described herein). Furthermore, the third width of the distal tip 216' is preferably large enough to ensure that the distal tip 216' is intact, and / or the distal tip 216' has a substantially cylindrical portion with a rounded and / or tapered periphery.

[0031] As further shown in Figure 10B, the proximal tapered portion 232' may have a first length (L1), the narrower segment 230' may have a second length (L2), the distal tapered portion 234' may have a third length (L3), and the distal tip portion 216' may have a fourth length (L4). The proximal tapered portion 232' may be more gradual, and its first length (L1) may be longer than its third length (L3), thereby allowing the proximal tapered portion 232' to withstand greater forces during insertion and preventing the formation of stress concentration points / weak points that would impair the strength / performance of the stylet 200'. The third length (L3) of the distal tapered portion 234' may be shortened so that the width of the stylet 200' can increase over a short distance from the narrower segment 230' to the distal tip portion 216'. For example, the proximal tapered portion 232' is preferably 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) is preferably about 0.2 to 0.6 inches, for example about 0.4 inches (about 5 to 15 mm, for example about 10 mm), the second length (L2) is preferably about 0.6 to 1.0 inches, for example about 0.8 inches (about 15 to 25 mm, for example about 20 mm), the third length (L3) is preferably about 0.04 to 0.2 inches, for example about 0.08 inches (about 1 to 5 mm, for example about 2 mm), and the fourth length (L4) is preferably about 0.02 to 0.06 inches, for example about 0.04 inches (about 0.5 to 1.5 mm, for example about 1 mm). Thus, the fifth length (L2+L3+L4) between the proximal end of the thin segment 230′ and the distal end of the stylet 200′ is preferably about 1.6 inches or less, for example about 0.6 to 1.4 inches (about 40 mm or less, for example about 15 to 35 mm) to provide desirable bending kinematic characteristics. The stylet 200′ is preferably made of nickel-titanium alloy or stainless steel, and this stylet is preferably coated with polytetrafluoroethylene (PTFE) or a hydrophobic coating.The stylet 200' may be without the navigation device (excluding the conductive coil 160, lead wires 162, 164, and tubular body 140), and this stylet may be used in conjunction with a separate navigation stylet (e.g., shown in Figures 17-19) or by itself (e.g., assembled with a PICC without another stylet) as a stiffening wire.

[0032] Figures 11A to 12 show a stylet 300 according to a fifth embodiment of the present invention. The stylet 300 preferably comprises a core wire 320, a tubular body 340, a conductive coil 360, and a magnetic hypotube 380. As shown in the figures, the core wire 320 is preferably received inside the magnetic hypotube 380, and the core wire 320 and the magnetic hypotube 380 are preferably received inside the tubular body 340. The stylet 300 preferably has substantially the same features as described above with respect to at least one of the stylets 100, 100', and 200 (which are incorporated herein unless otherwise specified), such features include the body and tip curve profiles, size, and stiffness profile with respect to the stylet 100, sections 110 to 116, 130, and the first and second curved sections α, β. The core wire 320 is preferably made of a nickel-titanium alloy, which is a kink-resistant alloy and provides additional advantages, but is inherently nonmagnetic. Therefore, in order to provide the desired properties of the present invention (e.g., navigation / electronic stylet including curved and suitable ground profiles), the magnetic hypotube 380 is preferably provided covering the distal portion of the core wire 320. The magnetic hypotube 380 is preferably short and preferably made of a permeable material, such as stainless steel or a similar material. The core wire 320 is preferably provided with a tapered portion 322 on the proximal side of the magnetic hypotube 380, and the hypotube 380 is preferably provided on the proximal side of the distal tip 326 of the core wire 320. The conductive coil 360 is preferably wound over the hypotube 380 to provide a passive sensor coil function for navigation as described herein.

[0033] The core wire 320 and the magnetic hypotube 380 are preferably extended distally from the tubular body 340 and at least partially covered with conductive epoxy 382 at a portion of the stylet 300 located distal to the tubular body 340. In some embodiments, the conductive epoxy 382 can fix the core wire 320, the tubular body 340, and the magnetic hypotube 380 to each other, and this conductive epoxy is preferably configured to guide the ECG signal to the tip portion 316. However, in some embodiments, a second epoxy (not shown) may bond the core wire 320 and the magnetic hypotube 380, while the conductive epoxy 382 covers the tip portion 316 to guide the ECG signal. Additionally or alternatively, the core wire 320 and the hypotube 380 are preferably welded together with sufficient exposed metal located at the tip portion 316 to guide the ECG signal. Additionally or alternatively, a conductive hypotube (not shown) may be provided to guide the ECG signal.

[0034] Figures 13A and 13B show a stylet 400 and catheter 450 according to a sixth embodiment of the present invention. The stylet 400 preferably has substantially the same features as described above with respect to at least one of the stylets 100, 100', 200, and 300 (which are incorporated herein unless otherwise specified), such features include a core wire, a tubular body 440, and first and second bends α, β. The stylet 400 preferably further has an intact distal segment 436, which reduces trauma to the posterior wall (BW) at the confluence (C) and facilitates the bending of the distal segment 436 downward along the posterior wall (BW) toward the RBVC compared to a stylet / PICC assembly that includes an outwardly positioned leading tip in the PICC only (e.g., without an intact distal segment). The distal segment 436 is preferably flexible and / or substantially compressible along the longitudinal axis of the stylet, and it is preferable that this distal segment extends distally to the distal end of the catheter 450 to make initial contact with the vein. For example, as shown in Figures 13A and 13B, the distal segment 436 is preferably J-shaped, configured to elastically flex when in contact with the posterior wall (BW) to reduce "tent-like" deformation compared to the more pointed distal portion. The core wire is preferably passed through the distal segment 436 such that the distal end 416 of the core wire extends proximal from the tubular body 440. The distal end 416 is preferably exposed to allow conduction of ECG signals, as further described herein. In another embodiment, as shown in Figures 14A to 14C, the stylet 400' received within the catheter 450' may have a distal segment 436' comprising a plurality of flexible members 436a' (e.g., wires) having a curved or looped shape that forms a basket. The flexible members 436a' may extend distally from the tubular portion 436b' and the stylet 400' may be joined to each other at the distal tip and / or loop back to the tubular portion 436b'.The flexible member 436a' is preferably elastically expandable (as shown in Figure 14A) and preferably collapses when retracted into the catheter 450' (as shown in Figure 14B). The flexible member 436a' can guide ECG signals for navigation purposes as described herein. Similar to the embodiments in Figures 13A and 13B, the distal segment 436' is preferably elastically flexed when it contacts the posterior wall (BW) at the confluence (C) (as shown in Figure 14C) and preferably has reduced "tent-like" deformation. In yet another embodiment, the stylet 400'' received within the catheter 450'' is preferably having a distal segment 436'' of a flexible mesh of multiple members. The distal segment 436'' is preferably elastically flexed when it contacts the posterior wall (BW) at the confluence (C) and preferably has reduced "tent-like" deformation. The distal segment 436″ can further guide the ECG signal as described herein. The function of the distal segments 436, 436′, 436″ can complement or replace the function of the first bend α and / or the second bend β, and thus, in some embodiments, the first bend α and / or the second bend β may be omitted, as a result the stylet 400 can have a pre-formed straight shape.

[0035] Figure 16 shows a stylet 500 according to a seventh embodiment of the present invention. The stylet 500 preferably has substantially the same features as described above with respect to at least one of the stylets 100, 100', 200, 300, and 400 (unless otherwise specified, these features are incorporated herein), including a core wire 520, a tubular body 540, a housing member 502, and first and second bends α and β. As shown in the figure, the distal end of the core wire 520 is preferably surrounded by the tubular body 540, thereby reducing trauma and enabling abrasive contact with the rear wall (BW) at the confluence (C). To enable ECG signal conduction, the tubular body 540 preferably has an opening 543 that penetrates the side wall of the tubular body 540 and is located between the proximal and distal ends of the tubular body 540. The opening 542 allows the ECG signal from the main body to be transmitted to the core wire 520. For example, the opening 542 is preferably located distal to the first and / or second bends α,β (for example, at the second bend β, as shown in the figure) in order to detect the location of the distal tip of the stylet 500. Thus, the core wire 520 is preferably configured to guide the ECG signal in a navigable manner while avoiding any trauma that may occur, even if the exposed distal tip of the core wire 520 is sharp.

[0036] Figures 17 to 19 show a pair of stylets 600, 601 according to an eighth embodiment of the present invention. The first stylet 600 is preferably configured to guide an ECG signal in a navigable manner, and the second stylet 601 is preferably configured to shape a catheter 650 for easy passage through the SVC, as will be further described herein with respect to at least one of the stylets 100, 100', 200, 300, 400, 500 and incorporated herein (unless otherwise specified). The first stylet 600 is preferably configured to have a housing 602, a tubular body 640, a core wire provided within the tubular body 640 and having a distal tip 616 for guiding an ECG signal, and a conductive coil 660 provided around the core wire within the tubular body 640, as will be further described herein with respect to at least one of the stylets 100, 100', 200, 300, 400, 500 and incorporated herein. The second stylet 601 is preferably a non-conductive elongated member or wire preformed with first and second bends α,β to facilitate the passage of the catheter 650 beyond the confluence (C). The first and second stylets 600, 601 are preferably inserted into separate lumens of the catheter 650, as shown in the first assembly in Figure 18. The first and second stylets 600, 601 are preferably inserted into the same lumen of the catheter 650, as further shown in the second assembly in Figure 19. In either assembly, manufacturing can be facilitated by separating the functions (e.g., ECG navigation and catheter insertion) between the first and second stylets 600, 601, for example, by allowing different materials with optimized mechanical and / or electrical properties to perform their respective functions.

[0037] Many features and advantages of the present invention are evident from the detailed description, and thus the appended claims are intended to include all such features and advantages of the present invention, which belong to the true spirit and scope of the invention. Furthermore, since many modifications and variations are readily conceivable to those skilled in the art, the present invention is not intended to be limited to the configuration and operation illustrated and described, and therefore all appropriate modifications and equivalents that fall within the scope of the present invention can be adopted.

Claims

1. It is a stylet, It has a core wire, and the core wire is Including a first preformed bend at a first angle, It includes a second preformed bend of a second angle, the second preformed bend being located distal to the first preformed bend, and the first angle being greater than the second angle. A stylet comprising a thin segment located distal to the second preformed curve and having a reduced width or reduced diameter that increases the degree of deflection of the distal tip.

2. The stylet according to claim 1, wherein the first angle is approximately 15 to 90 degrees with respect to the longitudinal axis of the stylet, and the arc length of the first preformed bend is approximately 3 to 7 inches (7.5 to 17.5 cm).

3. The stylet according to claim 1 or 2, wherein the second angle is approximately 8 to 15 degrees with respect to the longitudinal axis of the stylet, and the arc length of the second preformed bend is approximately 0.2 to 0.5 inches (0.5 to 1.3 cm).

4. The stylet according to any one of claims 1 to 3, wherein the first preformed bend and the second preformed bend are located 10 inches (25 cm) in total from the end of the distal tip of the core wire.

5. The stylet according to any one of claims 1 to 4, wherein the first angle is approximately 60° with respect to the longitudinal axis of the stylet, and the second angle is approximately 10° with respect to the longitudinal axis of the stylet.

6. The stylet according to any one of claims 1 to 5, wherein the first pre-formed bend is longer than the second pre-formed bend.

7. The stylet according to claim 6, wherein the first preformed bend has an arc length at least 4 inches (10 cm) longer than the second preformed bend.

8. The stylet according to any one of claims 1 to 7, wherein the first pre-formed curved portion and the second pre-formed curved portion are located in the same plane.

9. The stylet according to any one of claims 1 to 8, wherein the thin segment has a rounded and / or flattened cross-section.

10. The stylet according to any one of claims 1 to 9, wherein the core wire has a distal segment located between the thin segment and the distal tip, and the distal segment has a greater width or diameter than the thin segment.

11. The stylet according to claim 10, wherein the distal tip portion has a greater width or diameter than the distal segment.

12. The stylet according to any one of claims 1 to 11, wherein the core wire includes a proximal tapered portion located on the proximal side of the thin segment and a distal tapered portion located on the distal side of the thin segment.

13. The stylet according to claim 12, wherein the proximal tapered portion is longer than the distal tapered portion.

14. The stylet according to claim 12 or 13, wherein the proximal tapered portion includes a first tapered portion and a second tapered portion, and the first tapered portion is tapered at a larger angle than the second tapered portion.

15. A stylet according to any one of claims 1 to 14, further comprising a tubular body fitted onto the core wire.

16. The stylet according to claim 15, wherein the distal tip of the core wire extends distally to the tubular body, and the distal tip transmits an electrocardiogram (ECG) signal.

17. The stylet according to claim 15, wherein the tubular body has an opening in its side wall that allows fluid contact with the core wire.

18. The stylet according to any one of claims 15 to 17, further comprising a navigation device placed inside the tubular body and covering the core wire.

19. The stylet according to claim 18, wherein the navigation device comprises a conductive coil.

20. The stylet according to any one of claims 1 to 19, wherein the torque of the stylet is minimal or zero.

21. The stylet according to any one of claims 1 to 20, wherein the core wire further has an intermediate portion of about 1 to 3 inches (2.5 to 7.5 cm) extending between the first preformed bend and the second preformed bend.

22. The stylet according to any one of claims 1 to 21, wherein the core wire further has a distal portion having the thin segment, the distal portion extending for about 1 to 2 inches (2.5 to 5 cm) from the second preformed bend to the end of the distal tip.

23. The stylet according to any one of claims 1 to 22, further comprising a housing member located at the proximal end of the core wire.

24. The stylet according to any one of claims 1 to 23, wherein the core wire is made of a nickel-titanium alloy.

25. The stylet according to any one of claims 1 to 24, wherein the distal tip portion is formed of one of a J-shaped portion, a basket, or a mesh.

26. It is an assembly, The stylet according to any one of claims 1 to 25, An assembly including a second stylet that transmits ECG signals.

27. It is an assembly, The stylet according to any one of claims 1 to 25, An assembly including a catheter fitted into the stylet.

28. A low or non-torque stylet, Including a core wire, the core wire is It includes a first pre-formed bend at a first angle of approximately 15 to 90 degrees, It includes a second preformed bend at a second angle of approximately 8 to 15 degrees, the second preformed bend being located distal to the first preformed bend, and the first preformed bend being longer than the second preformed bend. Including an intermediate portion of about 1 to 3 inches (2.5 to 7.5 cm) extending between the first preformed bend and the second preformed bend, The first and second preformed bends are located together within 10 inches (25 cm) of the end of the distal tip of the core wire, and the distal portion includes a distal portion of about 1 to 2 inches (2.5 to 5 cm) located between the second preformed bend and the end of the distal tip, the distal portion has a narrow segment having a decreasing width or decreasing diameter that increases the degree of deflection of the distal tip, and the first and second preformed bends are located together within 10 inches (25 cm) of the end of the distal tip of the core wire. The system includes a navigation device provided around the core wire, A low-torque or non-torque stylet having a tubular body provided around the core wire and the navigation device.

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