Vascular dilator with stiff section

Abstract

A vascular dilator includes an elongated tube having a dilator tip attached to its distal end. A dilator lumen extends from a proximal end to a distal end of the vascular dilator through the elongated tube and the dilator tip. A stiff section of the vascular dilator is formed by the distal end of the elongated tube and a proximal end of the dilator tip, having bending stiffness that is higher than an average bending stiffness of the vascular dilator outside the stiff section

Description

[0001] Vascular Dilator with Stiff Section

[0002] Field of the Invention

[0003] The technical field generally relates to vascular dilators and introducer sheaths and components thereof for insertion into the body to provide intravascular access to various medical devices. This includes but is not limited to all arterial and vasculature access, abdominal and thoracic cavities, cerebrospinal, genito-urinary and gynaecological, upper gastrointestinal and colorectal procedures.

[0004] Background

[0005] Vascular access devices, including vascular introducer sheaths and vascular dilators, are now very commonplace in many intravascular procedures, such as transcatheter aortic valve replacement (TAVR), angioplasty and stenting. They generally facilitate access to the vascular system for the introduction of removable devices such as wires, balloons, pressure transducers and for the introduction and placement of implantable devices such as mechanical aortic valves and stents.

[0006] Vascular access devices are now typically inserted into the patient’s vessel through the skin percutaneously. Practices avoiding cutting the skin with a scalpel to expose the vessel for insertion have led to the safer and more frequent use of vascular access devices. Percutaneous insertion techniques involve the insertion of a needle or similar puncture device into the skin without first cutting the skin, to expose the vessel. Vascular access devices are advanced through the skin and into the vessel through the puncture. For patients, percutaneous techniques reduce blood loss and reduce the likelihood of human error that may occur while making scalpel incisions and reduce recovery times.

[0007] During percutaneous procedures, an introducer sheath is typically positioned at an entry point to a patient vessel and pushed through the vessel until the introducer sheath is firmly seated where it is required within the patient. The proximal end of the introducer sheath protrudes outside of the patient's body to provide an entry point for the subsequent insertion of additional or other intravascular devices. Frequently, a dilator is placed within the introducer sheath and is pushed through the vessel opening together with the introducer sheath to gradually open the vessel puncture site and allow the introducer sheath to enter while minimising vessel trauma. The percutaneous entry point is typically much smaller than the diameter of the introducer sheath and some force may be required to stretch the patient’s skin at the percutaneous opening to pass the vascular access device into the vessel. Therefore, any device having a groove, notch, or angular edge is likely to create a catch point where the skin may catch and tear, thereby causing site trauma and delay in recovery for the patient. Typical introducer sheaths therefore have a tapered distal end to provide a smooth transition to the dilator end and tip when used to open up the vasculature, to allow the introducer sheath to enter without excessive trauma.

[0008] Introducer sheath assemblies exist in many different forms. According to one particular class of assembly, the introducer sheath assembly has an introducer sheath and a vascular dilator having an enlarged tip mounted on a flexible shaft, which may be in the form of an elongated tube, having an outer diameter that is smaller than the dilator tip and also smaller than an inner diameter of the introducer sheath. The dilator tip has a size that corresponds in diameter to an outer diameter of the introducer sheath at the point at which the two engage. This ensures a smooth transition between the introducer sheath and the dilator tip. Such an assembly is disclosed in PCT / AU2019 / 051010 the contents of which are incorporated herein by reference in their entirety. Ideally, to avoid trauma, any transition between the dilator tip and the introducer sheath distal end should be 0.1mm or less. However, this is not always achieved, particularly due to manufacturing variations. Depending on the specific introducer sheath assembly, these variations may become more critical, making it more difficult to avoid a larger transition. Also, the introducer sheath distal end is prone to separation from the dilator tip around sharp curves, whereby a gap can be created at the outside of the curve between the introducer sheath distal end and the adjacent proximal extremity of the dilator tip. This creates a potential hazard of the end of the introducer sheath that can scrape the artery wall during delivery through tortuous anatomy. The distal end of the introducer sheath also needs to easily expand and retract which makes it difficult to keep it axially aligned with the dilator tip.

[0009] Current market introducer sheaths, including expandable introducer sheaths, have a constant diameter dilator / introducer with the distal end of the introducer sheath tapered down to minimise steps. This allows the introducer sheath to maintain a close fit with the dilator and avoid presenting an edge to the artery. However, this is not possible for all introducer sheath and dilator types. For introducer sheaths having multiple layers, the presence of multiple layers and relative movement between the layers makes it difficult if not impossible.

[0010] Summary of the Invention

[0011] Aspects of the present disclosure are to address at least the above-mentioned problems and / or disadvantages and to provide at least the advantages described below.

[0012] In a first aspect there is provided a vascular dilator according to claim 1. The vascular dilator has a variable bending stiffness along its length, especially provided by the section of relatively high stiffness that bridges the distal end of the elongated tube and the proximal end of the dilator tip. Therefore, the majority of the dilator remains relatively flexible. This configuration is intended to reduce the amount of bending of the vascular dilator at the location of the stiff section, consequently reducing the separation between the introducer sheath and the vascular dilator when navigating around sharp curves. In embodiments, the variable bending stiffness may occur as step change or be blended over a length of the elongate tube.

[0013] As used herein the terms ‘proximal’ and ‘distal’ are to be understood as opposite terms being relative to the direction of use of the article to which they refer. The term ‘distal’ is to be understood to refer to the end of the article first entering the patient, and the term ‘proximal’ is to be understood to refer to the end opposite the ‘distal’ end. For example, the ‘distal end’ may be nearest to the dilator tip such that in usage the distal end is closest to the patient and the proximal end is closest to the user.

[0014] Reference to “the distal end” or “the proximal end” intend to denote a region rather than a distinct point, for example, a region at which the elongated tube or the dilator tip terminate. For the avoidance of doubt, the most proximal or distal extremity of the elongated tube or the dilator tip will be referred to as the proximal or distal tip. Consequently, the term “outside the stiff section” is intended to denote a region of the vascular dilator contiguous to the stiff section and situated either proximally and / or distally from the stiff section. Subsequently a region “outside the stiff section” may also be located at the elongated tube and / or the dilator tip.

[0015] The skilled person will recognize that, particularly in vascular dilators with an enlarged dilator tip, the bending stiffness at the proximal end of the dilator tip may already be relatively higher compared to that of the elongated tube, due to factors such as increased thickness and / or diameter. Consequently, the difference in bending stiffness between the stiff section and the elongated tube near the stiff section may be greater than the difference in bending stiffness between the stiff section and the dilator tip. As a result, the stiff section may also provide reinforcement at least to the distal end of the elongated tube. In embodiments, the stiff section typically covers 2-20 mm of the distal end of the elongated tube and 2-20 mm of the proximal end of the dilator tip.

[0016] In embodiments, the stiff section may comprise one or more support element made of at least one of the group consisting of: metal tube insert in the lumen of the elongated tube; metal tube insert on the outer diameter of the elongated tube; braided or coiled reinforcement in the lumen or outer diameter of the elongated tube; a different polymer for the central elongated tube section and distal end; polymer with a reinforcement additive dispersed through the polymer (e.g., carbon fibre, glass fibre, mineral additive, talc, etc.); or the reinforced and / or stiff section may involve a variation in an outer diameter of the elongated tube - for example, a larger diameter at a distal end than central section.

[0017] Preferably, the one or more support elements is formed of a semi-rigid material. The term ‘semi-rigid’ is to be understood herein as defining a material or structure that is somewhat flexible but has a certain degree of stiffness or rigidity, as opposed to being completely flexible or completely rigid. In some embodiments, the one or more support elements has a length of 2.0 mm to 40.0 mm, preferably of 4.0 mm to 20.0 mm. In other embodiments, the one or more support elements has a length of preferably of 40.0 mm to 120.0 mm, preferably of 50.0 mm to 100.0 mm.

[0018] In an embodiment, the vascular dilator comprises a dilator hub attached to the elongated tube at its proximal end, preferably for attachment to an introducer sheath. In a further embodiment, the dilator hub comprises a securing means configured for attachment to the introducer sheath.

[0019] The term ‘layer’ is to be understood herein as a sheet or similar form of construction that may partially or entirely cover another article or object. The term ‘layer’ is not to be unduly limited in its construction so as to imply the presence of one or more other layers, articles or objects. For example, an article may comprise two or more layers that may be bonded at their edges rather than in a laminated or layered fashion and may still be regarded as two individual layers in their own right.

[0020] In another aspect of the disclosure, there is provided a vascular dilator assembly comprising a vascular dilator according to the first aspect and an introducer sheath. A length of the introducer sheath is arranged such that when the vascular dilator is introduced in the introducer sheath, a distal end of the introducer sheath is aligned with a proximal end of the dilator tip of the vascular dilator.

[0021] Due to the stiff section of the vascular dilator, the point at which the greatest degree of bending of the elongated tube occurs may be positioned further proximally from the distal end of the elongated tube, away from the attachment point between the dilator tip and the elongated tube. As a result, when the dilator tip and introducer sheath assembly is going through a sharp curve, this point of greatest bending will be located inside the introducer sheath, minimizing any gap that may be created at the outside of the curve between the distal end of the introducer sheath distal end and the adjacent proximal end of the dilator tip. The introducer sheath and the vascular dilator may have any suitable connection means to provide the functions of connection between them at the proximal end and prevent further relative movement thereof. As previously mentioned, the vascular dilator may comprise a dilator hub attached to the elongated tube at its proximal end and the dilator hub may include a securing means configured for attachment to the introducer sheath.

[0022] In an embodiment, the introducer sheath may further comprise an annular collar preferably including a securement fitting configured for receiving securing means and securing the vascular dilator thereto.

[0023] In another aspect of the disclosure, there is provided a vascular dilator comprising a dilator shaft, a dilator tip and a dilator lumen extending throughout the dilator shaft and the dilator tip; wherein the dilator shaft comprises a distal end including a stiffened section and a connecting section wherein a bending stiffness of the stiffened section is higher than an average bending stiffness of the remainder of the dilator shaft distal to the stiffened section; the connecting section being engaged within a cavity of the dilator tip; and wherein the dilator tip tapers from a maximum diameter near the dilator shaft to a distal end of the dilator tip.

[0024] In embodiments, the remainder of the dilator shaft may be substantially uniform in cross-section and may have a first uniform bending stiffness along its length. The stiffened section may have a second bending stiffness that is marginally greater or significantly greater than that of the dilator shaft. The second bending stiffness may at least be 5% or 10% or 30% or 50% or 100% greater than the first bending stiffness. Brief description of Drawings

[0025] The invention will be explained in more detail below with reference to drawings in which illustrative embodiments thereof are shown. They are intended exclusively for illustrative purposes and not to restrict the inventive concept, which is defined by the appended claims.

[0026] Figure 1 provides a front view of a prior art vascular dilator assembly showing a prior art introducer sheath and collar in dotted line transparency. A detailed view of portion A provided in Detail A.

[0027] Figure 2 provides a side perspective view of a vascular dilator. Detail B provides an enlarged view of the vascular dilator tip.

[0028] Figure 3 provides a side perspective exploded view of a vascular dilator and an introducer sheath assembly.

[0029] Figure 4 provides a longitudinal section of the vascular dilator according to a first embodiment of the invention

[0030] Figure 5 provides a longitudinal section of a portion of a vascular dilator according to a second embodiment of the invention.

[0031] Figure 6 provides a longitudinal section of a portion of a vascular dilator according to a third embodiment of the invention.

[0032] Figure 7 provides a longitudinal section of a portion of a vascular dilator according to a fourth embodiment of the invention.

[0033] Figure 8 provides a front view of a portion of a vascular dilator according to a fifth embodiment of the invention.

[0034] Figure 9 provides a front view of a portion of a vascular dilator according to a sixth embodiment of the invention.

[0035] Figure 10A provides a longitudinal section of a portion of a vascular dilator according to a seventh embodiment of the invention. Figure 10B and Figure 10C provide transversal sections of the vascular dilator, respectively at the distal end of the elongated tube and at the proximal end of the dilator tip.

[0036] Figure 11 provides a longitudinal section of a portion of a vascular dilator according to an eighth embodiment of the invention. Figure 1 provides a front view of a prior art vascular dilator assembly showing a prior art introducer sheath 150 in dotted line transparency. Detail A provides an enlarged front view of the dilator tip 130 and introducer sheath 150. The vascular dilator 100 is a tubular device for insertion into a vessel opening to reduce trauma while dilating the vessel for introduction of the introducer sheath 150.

[0037] In many prior art vascular dilator and introducer sheath assemblies of this kind, the design lengths of both vascular dilator 100 and introducer sheath 150 are such that when a dilator hub 110 is attached to a collar 151, a distal end 153 of a sleeve 152 of the introducer sheath 150 is nominally located in contact with a proximal end of the dilator tip 130 to provide a substantially smooth transition therebetween.

[0038] Detail A illustrates a detail view of the distal end 153 of sleeve 152 of introducer sheath 150 and the proximal end of dilator tip 130 of dilator 100, respectively. While the design lengths of both dilator 100 and introducer sheath 150 nominally locate dilator tip 130 at the distal end 153 of sleeve 152, manufacturing error in both the dilator 100 and introducer sheath 150 can lead to a gap 140 therebetween. The presence of gap 140 may prevent the smooth transition between dilator tip 130 and sleeve 152 and allow for catching of skin and tissue within gap 140, against distal end 153.

[0039] Figure 2 provides a side perspective view of vascular dilator 300. Vascular dilator 300 is broadly constructed from a dilator hub 310 at its proximal end 301, a dilator tip 330 with a tapered head at its distal end 302, and a dilator shaft 320 therebetween. A lumen extending from the proximal end 301 to the distal end 302 of vascular dilator 300 allows wires and small instruments to be passed therethrough. The lumen has a diameter of 0.3 mm to 3.0 mm, preferably of 1.0 mm to 2.0 mm.

[0040] Dilator hub 310 provides an attachment point for an introducer sheath (not shown) and allows the operator to handle the vascular dilator 300 during insertion of the vascular dilator into the introducer sheath. Dilator hub 310 is a rigid annular structure having a larger diameter portion 311 and a smaller diameter portion 312. The smaller diameter portion 312 is shaped to fit within an introducer sheath collar. Dilator hub 310 further comprises a securing means, here embodied in a bayonet fitting 313 formed at the surface of the smaller diameter portion 312 of dilator hub 310 body, and a button 340 slidably inserted within the larger diameter portion 311 of dilator hub 310 and coupled thereto by a biasing element (not shown) embodied in a spring, which is attached at one end to the button 340 and the other end to the dilator hub 310.

[0041] Dilator hub 310, button 340, dilator shaft 320, and dilator tip 330 all have a lumen passing therethrough such that wires and small instruments can be passed to the vessel. Detail B provides detail of dilator tip 330. introducer sheath. Dilator tip 330 is substantially conical or arrowhead shaped and increases in diameter from the distal end diameter of dilator shaft 320, at the interface 331 between dilator tip 330 and dilator shaft 320, to the maximum diameter of dilator tip 330, and tapers from the maximum diameter of dilator tip 330 to a rounded apex at the distal end of dilator tip 330. In this way, the interface 331 prevents an abrupt change of diameter from the dilator shaft 320 and the dilator tip 330. Dilator shaft 320 is substantially cylindrical and is attached at the distal end to dilator tip 330 and at the proximal end enters dilator hub 310 where it is attached to button 340. The coupling between button 340 and the biasing element allows dilator shaft 320 to slidably move longitudinally relative to dilator hub 310. As a result, starting from the uniform diameter of the dilator shaft 320, the diameter of the vascular dilator 300 increases at the interface 331, creating a smooth, sloped transition towards a maximum diameter of the dilator tip 330. The dilator tip 330 reaches its maximum diameter after the interface 331. From this maximum diameter, the dilator tip 330 tapers gradually towards the rounded apex at its distal end. This configuration minimizes an abrupt transition between the dilator shaft 320 and the dilator tip 330. The interface 331 has a length of 0.5 mm to 20.0 mm, preferably of 5.0 mm to 10.0 mm.

[0042] The dilator shaft 320 comprises an elongated tube 322 that has an outer diameter of 2.0 mm to 7.0 mm and / or a length of 100.0 mm to 1100.0mm. The dilator tip has an outer diameter of 4.0 mm to 12.0 mm. The maximum diameter of the dilator tip 330, e.g., at its proximal end, is of 1.1 to 2.5 times the outer diameter of the elongated tube 322. The dilator tip 330 has a length of 15 mm to 200 mm.

[0043] Figure 3 provides a side perspective exploded view of the components of a vascular dilator 300 and introducer sheath 40 assembly according to preferred embodiments of the invention. Vascular dilator 300 broadly comprises the dilator hub 310, button 340, securing means 313, a biasing element embodied in a coil spring 350, dilator shaft 320, and dilator tip 330. The dilator tip 330 has a proximal end 332 which is configured to attach to a distal end 321 of the dilator shaft 320. The proximal end 332 of the dilator tip 330 and the distal end 321 of the dilator shaft 320 may be attached by partially inserting the dilator shaft into the dilator tip. The distal end 321 of the dilator shaft 320 and the proximal end 332 of the dilator tip 330 are adapted to form a reinforced and / or stiff section of the vascular dilator 300, with bending stiffness higher than an average bending stiffness of the vascular dilator 300 outside the stiff section.

[0044] Introducer sheath 40 is broadly constructed of two main components; the rigid annular collar 41 and the sleeve 42. Collar 41 is a hollow structure constructed to allow materials to be fed into the inner lumen of sleeve 42 through the wider opening of the sleeve 42. Collar 41 is formed of a rigid material to allow a user to handle the collar 41 and pass an object or material therethrough. Collar 41 comprises a securement fitting 44, here embodied as a bayonet receiver, which terminates in an opening shaped to enable sleeve 42 to be placed and secured therein, thereby connecting the two components. Dilator hub 310 securely attaches to collar 41 by engaging securing means 313 to securement fitting 44 after insertion of dilator 300 into introducer sheath 40 to locate dilator tip 330 relative to the distal end 43 of sleeve 42 and prevent further relative movement thereof. The skilled person would recognize that other equivalent attachment and / or connection means between the dilator hub and the collar may be employed to secure the vascular dilator 300 and the introducer sheath 40 with one another.

[0045] Figure 4 provides a longitudinal section of the vascular dilator 400 according to a first embodiment of the invention. As previously mentioned, the vascular dilator 400 includes the dilator tip 430 and the dilator shaft 420. The dilator shaft 420 comprises an elongated tube 422 which includes a dilator shaft lumen 424 throughout. The dilator tip 430 further comprises a dilator tip lumen 431 throughout. When the dilator tip 430 is connected to the elongated tube 422, their lumens coincide to form a vascular dilator lumen extending throughout the vascular dilator 400 from its proximal end to its distal end.

[0046] The vascular dilator 400 further comprises a support element 450 located at the distal end 421 and extending up to a tip of the elongated tube 422. The support element 450 comprises a tube or tubular insert of a metal or polymer material and placed on an outer surface of the elongated tube 422. The proximal end 432 of the dilator tip 430 comprises an opening 433 providing access to a cavity 434 with a diameter larger than the lumen 431. The cavity 434 is configured to partially receive the distal end 421 of the elongated tube 422. In the depicted embodiment the cavity 434 is further configured to receive the support element 450 placed onto the elongated tube 422. Since the support element 450 is located at the distal end 421 of the elongated tube 422 and at the proximal end 432 of the dilator tip 430, the support element 450 provides a reinforcement of the vascular dilator resulting in a higher bending stiffness to this section of the vascular dilator 400. Here also called the reinforced and / or stiff section of the vascular dilator 400.

[0047] Figures 5 to 11 illustrate sections of a vascular dilator according to several embodiments of the invention. Features previously described with reference to the first embodiment may also be present the other embodiment and will not be repeated here for conciseness. In Figures 5 to 11, similar features are designated with reference numerals starting with 500, 600, 700 and so on, respectively, to distinguish the embodiments.

[0048] Figure 5 provides a longitudinal section of a portion of a vascular dilator according to a second embodiment of the invention. The vascular dilator 500 includes a support element 550 placed within the inner diameter of the distal end 521 and extending up to the tip of the elongated tube 522. The support element 550 comprises a tube or a tubular insert made of metal or polymer material and placed inside the lumen 524 of the elongated tube 522. This configuration ensures that the support element 550 is located at an outer diameter of the lumen 524, providing support from within the elongated tube 522.

[0049] Similar to the first embodiment, the proximal end 532 of the dilator tip 530 comprises an opening 533 that provides access to a cavity 534. The cavity 534 is configured to partially receive the distal end 521 of the elongated tube 522 along with the support element 550 placed inside it. Since the support element 550 is located at the distal end 521 of the elongated tube 522 and at the proximal end 532 of the dilator tip 530, the support element 550 provides a reinforcement of the vascular dilator resulting in a higher bending stiffness to this section of the vascular dilator 500 from inside the elongated tube 522, thereby providing the vascular dilator 500 with a stiff section.

[0050] Figure 6 provides a longitudinal section of a portion of a vascular dilator according to a third embodiment of the invention. The vascular dilator 600 includes a support element 650 embedded within a sidewall 625 of the elongated tube 622, starting at the distal end 621 and extending up to the tip of the elongated tube 622. Similar to previous embodiments, the support element 650 is a tube or a tubular insert made of a metal or polymer material. The support element 650 is integrated into the sidewall 624 of the elongated tube 622, providing internal reinforcement without occupying the lumen 624. Since the support element 650 is located at the distal end 621 of the elongated tube 622 and at the proximal end 632 of the dilator tip 630, the support element 650 provides a reinforcement of the vascular dilator resulting in a reinforced and / or stiff section. The integration of the support element 650 into the sidewall 625 may be achieved by removing material from the sidewall to form a recess to receive the support element 650 or by a lamination or reflow type processes. For example, at least the distal end 621 of the elongated tube 622 may be formed by placing the support element 650 around an inner tube, and then placing an outer tube around the support element 650. Subsequently, the inner tube, the support element 650 and the outer tube may be refl owed / 1 aminated and / or melted together. The outer tube may have material locally removed to achieve a continuous outer diameter to the elongated tube 622.

[0051] Figure 7 provides a longitudinal section of a portion of a vascular dilator according to a fourth embodiment of the invention. The vascular dilator 700 comprises a support element 750 extending from the distal end 721 of the elongated tube 722 up to beyond the tip of the elongated tube 722 and into the dilator tip 730. However, the support element 750 may also extend up to the tip of the elongated tube 722 to provide the similar reinforcement. The support element 750 comprises a hollow insert of a polymer material with a relatively high stiffness, in comparison to the stiffness of the elongated tube 722 and the dilator tip 731. Alternatively the polymer material of the insert may have a stiffness similar to that of the elongated tube 722 and / or the dilator tip 731 and comprises a reinforcement additive to increase its stiffness. The support element 750 is placed in between the dilator tip 730 and the elongated tube 722. The support element 750 includes a first section 751 that is arranged inside the dilator tip 730 and a second section 752, preferably integrally formed with the first section 751, and arranged outside the dilator tip 730 and on an outer surface of the distal end 721 of the elongated tube 722. The dilator tip 730 comprises a cavity 734 within the proximal end 732 of the dilator tip 730 that is configured to receive the first section 751 of the support element 750. The first section 751 of the support element 750 substantially follows the shape of the cavity 734, so that it fits tightly in the dilator tip 730. The first section 751 of the support element 750 further comprises a lumen 737 that is coincident with the lumen 731 of the dilator tip 730 and the lumen 724 of the elongated tube 722 when the dilator tip 730, the elongated tube 722 and the support element are assembled together.

[0052] The second section 752 of the support element 750 extends from the proximal end 732 of the dilator tip 730 and partially covers the distal end 721 of the elongated tube 722. The support element 750 further comprises an opening 753 at a proximal end of the second section 752 providing access to a cavity 736 with a diameter larger than the lumen 737. The cavity 736 is configured to partially receive the distal end 721 of the elongated tube 722. The support element 750, particularly in combination with the elongated tube 722, has a bending stiffness that is higher than the bending stiffness of the elongated tube 722 in a central and / or proximal section. Since the support element 750 is on the distal end 721 of the elongated tube 722 and within the proximal end 732 of the dilator tip 730, the support element 750 provides higher bending stiffness to this section of the vascular dilator 700, thereby forming the reinforced and / or stiff section of the vascular dilator 700.

[0053] Figure 8 provides a front view of a portion of a vascular dilator 800 according to a fifth embodiment of the invention. The vascular dilator 800 includes a support element 850 configured to reinforce the distal end 821 of the elongated tube 822, resulting in a reinforcement, i.e., higher stiffness, particularly of this section of the elongated tube 822. In the depicted embodiment, a coiled reinforcement is provided by the support element 850 comprising a coil, for example, a wire coil, placed on the outer surface 825 of the elongated tube 822, covering partially the distal end 821 of the elongated tube 822. In other embodiments, the coil may be placed within the elongated tube 822.

[0054] The coil has a pitch that increases proximally from the tip of the elongated tube 822, providing the highest stiffness at the distal end 821 of the elongated tube 822 to form the reinforced and / or stiff section of the vascular dilator 800. The cavity 834 of the dilator tip 830 is configured to partially receive the distal end 821 of the elongated tube 822, which includes a portion of a distal end of the support element 850. This arrangement allows a decrease of bending stiffness from the tip of the elongated tube 822 towards a central section of the elongated tube 822. Reinforcement of the distal end 821 of the elongated tube 822, similar to that provided by the coil, may be achieved by proximally decreasing the cross-section of the wire of the wire coil. The support element 850 may be laminated, embedded, or adhered to the outer surface of the elongated tube 822. For example, in a lamination process, the outer diameter of the elongated tube 822 is partially melted to increase the contact surface with the support element 850 and provide a geometrical capture as it cools down. In another example, the coil may be embedded into the outer surface of the elongated tube 822 by applying radial pressure, causing the coil to sink into the soft surface of the elongated tube 822 and adding a geometrical capture. Furthermore, other hollow structures, such as a tubular braid or a woven or multilayer structure, may also achieve the same result and may be applied by similar methods.

[0055] Figure 9 provides a front view of a vascular dilator 900 according to a sixth embodiment of the invention, and with a transparency through the elongated tube 922 and the dilator tip 931. The distal end 921 of the elongated tube 922 comprises three subsections: 921a, 921b, and 921c. The proximal end 932 of the dilator tip 930 is configured to receive the third subsection 921c, similar to the previously described embodiments, within a cavity 934. The first subsection 921a and the third subsection 921c have transversal partial cuts on the circumference of the sidewall of the elongated tube 922, thereby reducing the cross-sectional area of the elongated tube 922 at these subsections. The transversal partial cuts provide stress relief to the vascular dilator 900 at their location. As a result, the second subsection 921b has a higher bending stiffness than the first 921a and third 921c subsections, outside the second subsection 921b, thereby forming the stiff section of the vascular dilator 900. The cuts may be formed by laser cutting, machine cutting, or similar known methods. Similar modifications may also be made to the inside or outside of the proximal end 932 of the dilator tip 930, for example, within the cavity 934.

[0056] Figure 10A provides a longitudinal section of a portion of a vascular dilator 1000 according to a seventh embodiment of the invention. Figure 10B and Figure 10C provide transversal sections of the vascular dilator 1000, respectively at the distal end 1021 of the elongated tube 1022 and at the proximal end of the dilator tip 1030. The vascular dilator 1000 comprises a support element 1050 located at the distal end 1021 of the elongated tube 1022 and extending beyond the tip of the elongated tube 1022. The support element 1050 comprises a tri-lobed insert. The tri-lobed insert 1050 having three lobes 1062 arranged in a circular manner and joined to one another through an annular base 1063.

[0057] The sidewall of the elongated tube 1022 at the distal end 1021 is configured to receive the lobed insert. In the depicted embodiment, the lobed insert is a tri-lobed insert, however, the insert may include one non-tubular portion or two, four or more lobes or portions. The sidewall includes three recesses 1061 that extend longitudinally along the direction of the elongated tube 1022 and are embedded within the thickness of the sidewall. These recesses 1061 are spaced in a circular manner around the circumference of the sidewall. The proximal end 1032 of the dilator tip 1030 is configured to partially receive the distal end 1021 of the elongated tube 1022 and the tri-lobed insert, thereby forming a reinforced and / or stiff section by the distal end 1021 of the elongated tube 1022 and the proximal end 1032 of the dilator tip 1030. Alternatively, the lobes of the support element may be connected by a C-shaped base, or they may be independent of each other. In the latter case, the support element may not need to extend beyond the tip of the elongated tube 1022, and the lobes may only remain within the recesses.

[0058] Figure 11 provides a longitudinal section of a portion of a vascular dilator 1100 according to an eighth embodiment of the invention. The vascular dilator 1100 comprises a dilator shaft 1120, which includes two concentric elongated tubes, wherein an inner tube 1122a is located within an outer tube 1122b. At a distal end 1121 of the dilator shaft 1120, the inner tube 1122a extends more distally than the outer tube 1122b, protruding beyond a distal tip of the outer tube 1122b. The depicted embodiment further comprises a support element 1150 comprising a tube, such as an hypotube. Alternatively, the support element 1150 may have a cross-sectional C-shape. The support element 1150 is inserted between the two concentric elongated tubes 1122a and 1122b. The support element 1150 extends distally up to a distance beyond the distal tip of the inner tube 1122a and before the distal tip of the outer tube 1122b. This configuration provides the distal end 1121 of the elongated tube 1122 with higher stiffness.

[0059] The proximal end 1132 of the dilator tip 1130 is configured to partially receive the distal end 1121 of the dilator shaft 1120, with the inner tube 1122a, the support element 1150 and the outer tube 1122b. The proximal end 1132 of the dilator tip 1130 comprises an opening 1133 providing access to a cavity 1134. Specifically, the cavity 1134 has a two-step shape to tightly fit around the shape of the distal end 1121 of the dilator shaft 1120 formed by the concentric elongated tubes 1122a, 1122b and the support element 1150. Since the support element 1150 spans the distal end 1121 of the concentric elongated tubes 1122a, 1122b and the proximal end 1132 of the dilator tip 1130, the support element 1150 provides the dilator tip 1130 with a reinforces and / or stiff section.

Claims

Claims1. A vascular dilator comprising: an elongated tube; a dilator tip attached to the elongated tube at a distal end of the elongated tube, wherein a stiff section of the vascular dilator is formed by the distal end of the elongated tube and a proximal end of the dilator tip, wherein bending stiffness in the stiff section is higher than an average bending stiffness of the vascular dilator outside the stiff section.

2. The vascular dilator according to claim 1, wherein the distal end of the elongated tube extends over 2 - 20 mm in a longitudinal direction of the elongated tube.

3. The vascular dilator according to claim 1, wherein the proximal end of the dilator tip extends over 2 - 20 mm in a longitudinal direction of the dilator tip.

4. The vascular dilator according to claim 1, wherein the stiff section extends over 4 - 40 mm in a longitudinal direction of the vascular dilator.

5. The vascular dilator according to claim 1, wherein the stiff section comprises a metal insert.

6. The vascular dilator according to claim 1, wherein the stiff section comprises a braided or coiled reinforcement.

7. The vascular dilator according to claim 1, wherein the stiff section comprises a polymer insert with a relatively high stiffness.

8. The vascular dilator according to claim 1, wherein the stiff section comprises a polymer insert with reinforcement additive.

9. The vascular dilator according to claim 1, wherein the stiff section has a larger outer diameter compared to the diameter of the elongated tube.

10. The vascular dilator according to any preceding claim, wherein the dilator tip is substantially conical and comprises an interface wherein a diameter of the dilator increases in diameter from the distal end of the elongated tube to a maximum diameter of the dilator tip, and wherein the dilator tip tapers from the maximum diameter of dilator tip to a rounded apex at the distal end of dilator tip.

11. The vascular dilator according to claim 10, wherein the maximum diameter of the dilator tip is of between 1.1 to 2.5 times the diameter of the elongated tube.

12. The vascular dilator according to any preceding claim, further comprising a vascular dilator lumen extending from a proximal end to a distal end of the vascular dilator; wherein the a vascular dilator lumen has a diameter of 0.3 mm to 3.0 mm.

13. The vascular dilator according to any preceding claim, wherein the elongated tube has an outer diameter of 2.0 mm to 7.0 mm and / or a length of 100.0 mm to 1100.0mm.

14. The vascular dilator according to any preceding claim, wherein, the dilator tip has an outer diameter of 4.0 mm to 12.0 mm and / or a length of 15 mm to 200 mm, preferably a maximum diameter of the dilator tip is of 1.1 to 2.5 times the outer diameter of the elongated tube.

15. The vascular dilator according to any preceding claim, further comprising a dilator hub attached to the elongated tube at its proximal end, preferably for attachment to an introducer sheath.

16. The vascular dilator according to claim 15, wherein the dilator hub is a rigid annular structure having a larger diameter portion and a smaller diameter portion,and wherein the smaller diameter portion is configured to fit within a collar of the introducer sheath collar.

17. The vascular dilator according to claim 15 or claim 16, wherein the dilator hub further comprises a securing means, formed at a surface of the smaller diameter portion, and a button slidably inserted within the larger diameter portion and coupled thereto by a biasing element, which is attached at one end to the button and the other end to the dilator hub.

18. A vascular dilator assembly comprising a vascular dilator according to any of the preceding claims and an introducer sheath, wherein a length of the introducer sheath is arranged such that when the vascular dilator is introduced in the introducer sheath, a distal end of the introducer sheath is aligned with a proximal end of the dilator tip of the vascular dilator.

19. The vascular dilator assembly according to claim 18, wherein the introducer sheath tapers between its proximal end and its distal end.

20. The vascular dilator assembly according to claim 18 or claim 19, wherein the introducer sheath comprises a dual layer sleeve.

21. The vascular dilator assembly according to any of the claims 18 to 20, wherein the introducer sheath further comprises an annular collar, preferably including a securement fitting configured for receiving securing means and securing the vascular dilator thereto.

22. The vascular dilator assembly according to claim 21, wherein the securing means of the vascular dilator engage with the securement fitting of the introducer sheath after insertion of the dilator into the introducer.

23. A vascular dilator comprising a dilator shaft, a dilator tip and a dilator lumen extending throughout the dilator shaft and the dilator tip;wherein the dilator shaft comprises a distal end including a stiffened section and a connecting section, the connecting section being engaged within a cavity of the dilator tip, wherein a bending stiffness of the stiffened section is higher than an average bending stiffness of the remainder of the dilator shaft distal to the stiffened section; and wherein the dilator tip tapers from a maximum diameter near the dilator shaft to a smaller diameter at the distal end of the dilator tip.

Images