Introducer sheath assembly with expanding actuator

Abstract

The invention relates to an introducer sheath assembly, comprising: a sheath having a distal end, a proximal end, an interior diameter, an exterior diameter, a lumen, and a length extending from the distal end to the proximal end, the sheath being configured to 5 be inserted into the patient's vasculature and to expand in a direction radially outward from the lumen; and a dilator comprising: a dilator tip being configured to abut to and extend from the distal end of the sheath; and an elongated dilator body coupled to the dilator tip and extending through the lumen of the sheath, and an actuator being configured to slide within the lumen in a direction from the proximal end of the sheath 10 towards the distal end of the sheath to expand the sheath in a direction radially outward from the lumen, and wherein the actuator is configured to radially expand and / or move longitudinally such that the interior diameter of the distal end of the sheath is increased.

Description

[0001] INTRODUCER SHEATH ASSEMBLY WITH EXPANDING ACTUATOR

[0002] Field of the Invention

[0003] The technical field generally relates to 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. Practice away from cutting the skin with a scalpel to expose the vessel for insertion has 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.

[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 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 with the introducer sheath to gradually open the vessel puncture site and allow the sheath to enter while minimising vessel trauma. To facilitate smooth entry during percutaneous access of a large bore introducer sheath, it is desired to have a smooth transition between the sheath and the retractable dilator. To facilitate smooth transition, it is desired that the sheath and a tip of the retractable dilator have a gapless transition in the longitudinal direction and a similar exterior diameter at the transition point. Typical expanding introducer sheaths have an inner diameter similar to the exterior diameter of the dilator to allow the dilator to be easily retracted from the sheath. However, these passive-expanding introducer sheaths are unable to provide a gapless or abutting transition due to the lead in geometry of the proximal surface of the dilator tip required to maintain reasonable forces for passive retraction of the dilator into the expanding sheath. The sheath usually has a diameter and elasticity that ensures that the dilator can be retracted easily without excessive force.

[0008] According to one particular class of introducer sheath, the dilator has an enlarged tip mounted on a flexible shaft or body, which may be in the form of an elongated tube, having an exterior diameter that is smaller than the dilator tip and also smaller than an inner diameter of the introducer sheath. The dilator tip has a diameter that corresponds to an exterior diameter of the introducer sheath at the point at which they contact. This seeks to ensure 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.

[0009] In some devices, an actuation mechanism may be provided to locally expand the distal end of the introducer sheath to facilitate the removal of the dilator. This allows an axially facing edge on the trailing edge of the dilator to mate against the distal end of the sheath, to facilitate a gapless transition between dilator and sheath. Such an actuation mechanism is for example known from patent publication WO 2020 / 092253 A2.

[0010] WO 2020 / 092253 A2 discloses a plug coupled to the dilator and configured to move from a first position in which the plug has a first diameter to a second position in which the plug has a second diameter that is greater than the first diameter and greater than the interior diameter of the sheath, the plug in the first position being configured to fit within the lumen of the sheath, and the plug in the second position having a length that is less than the entire length of the sheath and being configured to slide within the lumen of the sheath in a direction from the distal end of the sheath towards the proximal end of the sheath to expand the sheath in the direction radially outward from the lumen. To move the plug from the first position to the second position, the dilator and plug are first moved to an advanced position distally beyond the opening of the sheath. Thereafter, the inner shaft of the dilator is partially retracted, or partially slid proximally, relative to the plug. The force applied by the dilator to the plug causes the plug to flare open. It is clear that such a widened plug positioned beyond the opening of the sheath can cause vessel trauma.

[0011] Object of the Invention

[0012] An object of the invention may be to provide an introducer sheath assembly allowing smooth transition between an expandable sheath and the dilator while being able to prevent vessel trauma during insertion or retraction of the dilator. Another object of the invention may be to provide a re-usable retractable dilator.

[0013] Summary of the Invention

[0014] 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.

[0015] The object and other objects which will become apparent from the following description are achieved at least in part by an introducer sheath assembly according to the independent claim. Embodiments are defined by the dependent claims.

[0016] This object is achieved by an introducer sheath assembly comprising a sheath, a dilator and an actuator. The sheath has a distal end, a proximal end, an interior diameter, an exterior diameter, a lumen, and a length extending from the distal end to the proximal end, the sheath being configured to be inserted into a patient’s vasculature and to expand in a direction radially outward from the lumen. The dilator comprises a dilator tip being configured to abut to and extend from the distal end of the sheath; and an elongated dilator body coupled to the dilator tip and extending through the lumen of the sheath. The actuator being configured to slide within the lumen in a direction from the proximal end of the sheath towards the distal end of the sheath to expand the sheath in the direction radially outward from the lumen. Said actuator is configured to radially expand and / or move longitudinally such that the interior diameter of the distal end of the sheath is increased.

[0017] 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 sheath 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.

[0018] In the present context of the interaction between the distal end of the sheath and the dilator tip, abut is intended to denote an engaging surface between the two parts that is substantially radially extending, with respect to a longitudinal axis of the assembly. It will be understood that such an abutment will not be able to provide an expanding force to expand the sheath on applying a withdrawing force to the dilator. The abutment will however minimize a gap between these two elements in the longitudinal direction. This may not be the only point of engagement between the dilator and the sheath. For instance, an inner circumferential surface of the sheath at the distal end or distal tip may be configured to contact an outer circumferential surface of part of the dilator tip, preferably at the proximal end of the dilator tip. This is advantageous if the dilator tip comprises a section with a consistent exterior diameter, then it is sufficient for the inner circumferential surface of the sheath to contact the outer circumferential surface of the dilator tip at any point along this section.

[0019] The diameter of the dilator tip may be greater than the diameter of the dilator body, thereby forming a proximal end surface of the dilator tip that connects to the dilator body. In this case, a distal end surface of the sheath, defined by the thickness of the sheath at the distal end, may be configured to abut the proximal end surface of the dilator tip. This ensures a more even outer surface at the transition between the dilator body and dilator tip, thereby minimising vessel trauma during insertion. Consequently, the actuator, in combination with the described configurations of the dilator and sheath, facilitates a smooth transition between the dilator tip and the sheath while still enabling straightforward retraction of the dilator when needed.

[0020] The actuator may be configured to radially expand using a self-expanding element such as a coiled, clock spring like element which is attached to the dilator body behind the dilator tip. The self-expanding element is configured to expand to a set diameter similar to that of the dilator tip, which expands the distal end of the sheath. The user may pull back an actuator cover to allow radial expansion of the self-expanding element.

[0021] Alternatively, the actuator may be configured to move longitudinally using a ring or a segmented ring of a diameter similar to the diameter of the dilator body, the ring or segmented ring may initially sit within a hub of the dilator or available space within the sheath. The ring is required to be pushed or pulled up towards the dilator tip, expanding the sheath when the dilator is required to be removed. The ring may have an exterior diameter similar to the diameter of a proximal end of the dilator tip and greater than the interior diameter of the sheath before expansion.

[0022] Alternatively, the actuator may be configured to radially expand and move longitudinally using an actuation mechanism that locally expands the sheath using a single lumen tube, which is free to slide over the dilator body. The actuator may be formed by the single lumen tube with a series of flexible features, such as arms, at a distal end of the single lumen tube. When the single lumen tube is actuated, it may move distally and towards the dilator tip, the flexible features may expand radially outward by engaging a wedge profile of a dilator shoulder, the dilator shoulder being located proximally from the dilator tip. The wedge profile may provide a gradual transition from the dilator body to the dilator shoulder.

[0023] Advantageously, the dilator body and the actuator are provided inside the sheath and there is no need to position any element, apart from the dilator tip, distally beyond the opening of the sheath to achieve the function of expand the sheath in the direction radially outward. Thus, reducing the risk of damaging the vasculature when the actuator is activated. In addition, the invention increases the diameter of the sheath while the actuator is within the lumen of the sheath and without pulling an element of the dilator from outside the sheath to inside the sheath. Thus, reducing the risk of damaging the sheath due to applying a longitudinal force to the distal end of the sheath with the dilator tip. Moreover, the invention allows for a compact system. Since no pulling is required, the actuated elements do not need to expand larger than the diameter of the dilator tip.

[0024] In an embodiment, the present invention relates to the introducer sheath assembly as described above, wherein the actuator is coupled to the dilator and is configured to move from a first position in which the actuator has a first diameter smaller than the interior diameter of the sheath to a second position in which the actuator has a second diameter that is greater than the first diameter and greater than the interior diameter of the sheath before expansion. The actuator may have a first diameter slightly larger than the sheath diameter in its relaxed condition, to achieve a nominal preload condition once they are assembled. But when assembled the first diameter of the actuator will always be smaller than (or equal to) the interior sheath diameter. This means that before assembly, the actuator could have larger diameter that the sheath, requiring the sheath to radially expand slightly during assembly. In an embodiment, the present invention relates to the introducer sheath assembly as described above, wherein the actuator is positioned between the dilator body and the dilator tip, and wherein the actuator is configured to radially expand from the first position in which the actuator has the first diameter to the second position in which the actuator has the second diameter such that the interior diameter of the distal end of the sheath is increased. In this embodiment, the actuator may be part of the dilator and / or it may be attached to the dilator between the dilator body and the dilator tip. Additionally, in an unexpanded state, the actuator may adopt a shape similar to that of a dilator shoulder as described above.

[0025] In an alternative embodiment, the present invention relates to the introducer sheath assembly as described above, wherein the dilator further comprises a dilator shoulder positioned between the dilator body and the dilator tip, wherein the dilator shoulder has an exterior diameter that is greater than an exterior diameter of the dilator body and smaller than the interior diameter of the sheath before expansion; and wherein the actuator is configured to slide from the dilator body to the dilator shoulder to move from the first position to the second position such that the interior diameter of the distal end of the sheath is increased to the second diameter.

[0026] In an embodiment, a distal end of the actuator is configured to expand from the first diameter to the second diameter when the actuator is moved from the dilator body to the dilator shoulder.

[0027] In an embodiment, the actuator is formed by a single lumen tube with a scroll expander, a buckling expander, or mated C-profiles at a distal end of the single lumen tube.

[0028] In an embodiment, the actuator has an exterior diameter approximately equal to the exterior diameter of a proximal end of the dilator tip and greater than the interior diameter of the sheath before expansion, and wherein the actuator is configured to move from a proximal position within the sheath to a distal position near the distal end of the sheath. In a further embodiment, the actuator is formed by a solid ring or a segmented ring.

[0029] In an embodiment, the dilator body has an exterior diameter smaller than the exterior diameter of the proximal end of the dilator tip. This may result in a proximal end surface of the dilator tip with the dilator tip exhibiting greater bending stiffness relative to the dilator body. This differential stiffness allows the dilator body to be more flexible, facilitating easier insertion through the sheath and into the patient's vasculature. Additionally, this configuration enables a smoother transition between the dilator and the sheath. Specifically, the sheath may be configured with an exterior diameter approximately equal to the exterior diameter of the dilator tip, allowing a distal end surface of the sheath, defined as the region defined by the thickness of the sheath, between its interior and exterior diameters, at the distal end, to abut the proximal end surface of the dilator tip.

[0030] In an embodiment, the dilator tip comprises a tapered head that is substantially conical, and wherein at a proximal end, the tapered head tapers outward from the distal end of the dilator body at an interface between the dilator body and the tapered head, to a maximum diameter of the tapered head, and tapers inward from the maximum diameter of tapered head to a rounded apex at the distal end of tapered head.

[0031] In an embodiment, the introducer sheath assembly further comprises an elongated pusher configured to push the actuator distally through the lumen of the sheath. The elongated pusher facilitates the operation of the actuator from a proximal end of the dilator. For example, the elongated pusher may facilitate the single lumen tube to be actuated by pushing it distally towards the dilator tip.

[0032] In an embodiment, the dilator further comprises a dilator hub at its proximal end, which allows an operator to handle the dilator, particularly during insertion of the dilator into the sheath.

[0033] In an embodiment, the elongated pusher extends longitudinally from the dilator hub to the actuator. Advantageously, this allows the actuator to be operated from the proximal end of the introducer sheath assembly and from an outside of a patient after the sheath has been inserted into the patient’s vasculature.

[0034] In an embodiment, the hub comprises a slider connected to the elongated pusher and configured to allow a user to operate the elongated pusher. The slider may be configured to slide a predetermined distance, providing precise control over the required sliding movement to radially expand and / or longitudinally slide the actuator. For instance, the slider may sufficiently move to push the single lumen tube distally until it reaches and / or abuts the dilator tip. In a further embodiment, the elongated pusher comprises a continuous cylinder or a plurality of elongated members arranged in a cylindrical configuration. The sheath and the 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.

[0035] In an embodiment, the dilator hub may be 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 sheath.

[0036] The dilator hub may further comprise 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. This arrangement allows the dilator body to slide longitudinally relative to the dilator hub and within the sheath. The biasing element maintains a proximal bias on the dilator tip toward the distal end of the sheath. This is particularly advantageous in embodiments in which the dilator tip has a larger diameter than the dilator body. The bias element may ensure abutment between the proximal surface of the dilator tip and the distal surface of the sheath. This further prevents the formation of a gap in a longitudinal direction between the sheath and the dilator tip, which could otherwise increase the risk of vessel trauma.

[0037] In a further embodiment, the sheath may further comprise a securement fitting configured for receiving the securing means of the dilator hub and securing the dilator thereto. In this manner, the securing means of the dilator hub engages with the securement fitting of the sheath after insertion of the dilator into the sheath.

[0038] In an embodiment, the sheath comprises a dual layer sleeve including a continuous elastomeric outer layer and an expandable inner layer discontinuous at least in part, and wherein the dilator tip is configured to at least abut to and extend from the distal end of the continuous elastomeric outer layer. Preferably the proximal end of the dilator tip is configured to abut the distal end of the outer layer to ensure a smooth transition between the sheath and the dilator tip. The expandable inner layer provides outward annular resistance when coiled. This rigidity helps in creating a channel and resisting collapse or buckling when the sheath is being introduced into the patient’s vasculature. The elastomeric outer layer provides resistive pressure against expansion of the sheath and forces radial retraction when the dilator is longitudinally retracted. This configuration of the sheath results in an even and passive radial retraction of the sleeve to its original diameter as a medical device or the dilator is passed through the sheath, which also enables the safe removal of the sheath after a procedure.

[0039] In an embodiment the sheath is longitudinally tapered at least partially between the proximal end and the distal end of the sheath. This facilitates insertion into the patient’s vasculature. The degree of tapering may be critical for certain uses, for instance, for TAVR (transcatheter aortic valve replacement) procedures where a valve may well be larger than the patient's femoral artery, the degree of tapering preferably facilitates ease of entry of the sheath into an opening in the vessel where the opening of the vessel and the vessel itself may be gently stretched and enlarged by insertion of the sheath. Furthermore, tapering of the sheath may permit expansion of the sheath with less introducing force than a non-tapered sheath.

[0040] Brief Description of Drawings

[0041] 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.

[0042] Figure 1 illustrates a front view of a prior art introducer sheath assembly showing a prior art dilator and sheath. A detailed view of a portion A of the introducer sheath assembly of Figure 1 is provided in Detail A;

[0043] Figure 2 illustrates a side perspective view of a prior art dilator. Detail B provides an enlarged view of the dilator tip;

[0044] Figure 3 illustrates a side perspective exploded view of the components of a dilator and sheath according to the prior art;

[0045] Figures 4A to 4E illustrate a dilator including an actuator in a first position according to the invention;

[0046] Figures 4A illustrates a perspective view of a dilator;

[0047] Figure 4B and 4C illustrate respectively a perspective and section view of the dilator of Figure 4A inserted into the lumen of a sheath;

[0048] Figure 4D illustrates an enlarged view of the distal section of the dilator of Figure 4A;

[0049] Figure 4E illustrates an enlarged section view of the distal section of the dilator and sheath of Figure 4B and 4C; Figures 5A to 5E illustrate the dilator and sheath of Figures 4A to 4E with the actuator in a second position;

[0050] Figure 5D illustrates an enlarged view of the distal section of the dilator of Figure 5 A;

[0051] Figure 5E illustrates an enlarged section view of the distal section of the dilator and sheath of Figure 5B and 5C;

[0052] Figure 6 illustrates a perspective view of a dilator according to another embodiment of the invention wherein the actuator comprises a scroll expander;

[0053] Figure 7 illustrates a perspective view of a dilator according to another embodiment of the invention wherein the actuator comprises a buckling element;

[0054] Figure 8 illustrates a section view of a dilator and sheath according to another embodiment of the invention wherein the actuator comprises a segmented ring;

[0055] Figures 9A and 9B illustrate perspective views of the dilator of Figure 8; and

[0056] Figures 9C and 9D illustrate perspective views of a dilator according to another embodiment of the invention wherein the actuator comprises a ring.

[0057] Detailed Description of Embodiments

[0058] Figure 1 illustrates a front view of a prior art introducer sheath assembly showing a prior art dilator and sheath. The detail provides an enlarged front view of the dilator tip 130 and sheath. 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.

[0059] In many prior art introducer sheath assemblies of this kind, the design lengths of both dilator 100 and sheath 150 are such that when dilator hub 110 is attached to collar 151, the distal end 153 of sleeve 152 is nominally located in contact with the proximal end of tapered head 130 to provide a substantially smooth transition therebetween.

[0060] Detail A illustrates a detail view of the distal end 153 of sleeve 152 and the proximal end of tapered head 130 of the dilator 100. While the design lengths of both dilator 100 and introducer sheath 150 nominally locate tapered head 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 tapered head 130 and sleeve 152 and allow for catching of skin and tissue within gap 140, against distal end 153. Figure 2 illustrates a side perspective view of a prior art dilator 300. Dilator 300 is broadly constructed from a dilator hub 310 at its proximal end 301, a tapered head 330 at its distal end 302, and a dilator body 320 therebetween. A lumen from the proximal end 301 to the distal end 302 of dilator 300 allows wires and small instruments to be passed therethrough.

[0061] Dilator hub 310 allows the operator to handle the dilator 300 during insertion of the 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 also provides an attachment point for a sheath comprising a securing means 313 embodied in a bayonet fitting formed at the surface of the smaller diameter portion 312 of dilator hub 310 body. The dilator hub 310 further comprises a button 340 slidably inserted within the larger diameter portion 311 of dilator hub 310 and coupled thereto by a biasing element 390 (see Figure 3) embodied in a spring, which is attached at one end to the button 340 and the other end to the dilator hub 310.

[0062] Dilator hub 310, button 340, dilator body 320, and tapered head 330 contain a lumen therethrough such that the introducer sheath can be traversed over a wire, and small instruments can be passed to the vessel. The detail provides detail of tapered head 330, which is further used to ease insertion of dilator 300 into an introducer sheath. Tapered head 330 is substantially conical or arrowhead shaped and tapers outward from the distal end diameter of dilator body 320 at the interface 331 between tapered head 330 and dilator body 320, to the maximum diameter of tapered head 330, and tapers inward from the maximum diameter of tapered head 330 to a rounded apex at the distal end of tapered head 330.

[0063] The space between the interface 331 between tapered head 330 and the dilator body 320 and the maximum diameter of tapered head 330 provides a catch point for a patient’s vessel when introduced with a sheath.

[0064] Dilator body 320 is substantially cylindrical and is attached at the distal end to tapered head 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 body 320 to slidably move longitudinally relative to dilator hub 310.

[0065] Figure 3 illustrates a side perspective exploded view of the components of a dilator 300 and introducer sheath 400 according to the prior art. Dilator 300 broadly comprises the dilator hub 310, button 340, securing means 313, a biasing element embodied in a 0.1 N / mm to 10 N / mm conventional stainless steel coil spring 390, dilator body 320, and tapered head 330. Introducer sheath 400 broadly comprises a rigid annular collar 410, an elongated dual layer sleeve 420, and a securement fitting 440 embodied in a bayonet receiver suitable for receiving securing means 313 and securing dilator 300 thereto.

[0066] Introducer sheath 400 is broadly constructed of two main components; a rigid annular collar 410 and an elongated dual layer sleeve 420. Collar 410 is a hollow structure constructed to allow materials to be fed into the inner lumen of sleeve 420 through the wider opening of the sleeve 420. Collar 410 is formed of a rigid material to allow a user to handle the collar 410 and pass an object or material therethrough. Collar 410 comprises a securement fitting 440 and terminates in an opening shaped to enable sleeve 420 to be placed and secured therein, thereby connecting the two components.

[0067] Dilator hub 310 securely attaches to collar 410 by engaging securing means 313 to securement fitting 440 after insertion of dilator 300 into introducer sheath 400 to locate tapered head 330 relative to the distal end 430 of sleeve 420 and prevent further relative movement thereof.

[0068] Figures 4A to 9C illustrate different embodiments of the introducer sheath assembly according to the invention. Figures 4A to 4E illustrate a dilator 500 including an actuator 600 in a first position according to the invention. Figure 4A illustrates a perspective view of the dilator 500 comprising a dilator tip 530, a dilator shoulder 550 located proximal to the dilator tip 530 and a dilator hub 510. Like the introducer sheath assembly described with reference to Figures 1 to 3, the dilator tip 530 has a tapered head that is substantially conical, and has a maximum diameter at its proximal end, where it is configured to contact the sheath 200.

[0069] The dilator 500 further comprises an elongated dilator body 520 coupled to the dilator tip 530 on a distal end and to the dilator hub 510 on the proximal end. The diameter of the dilator body 520 is smaller than the diameter of the proximal end of the dilator tip 530. The dilator 500 further comprises a dilator lumen 570 extending throughout a length of the dilator 500.

[0070] The actuator 600 is connected to a distal end of an elongated pusher 630. In the depicted embodiment, the elongated pusher 630 comprises a continuous cylinder placed over the dilator body 520. The dilator hub 510 includes a slider 670 coupled to a proximal end of the elongated pusher 630 and is configured to operate the elongated pusher 630. The actuator 600 is coupled to the dilator body 520 and, in the first position, is located proximal to the dilator shoulder 550. Figure 4B and 4C illustrate respectively a perspective and section view of the dilator 500 of Figure 4A inserted into a sheath 200. The sheath 200 comprises a rigid annular collar 210 and a sleeve 220. As illustrated in Figure 4B and 4C, when the dilator 500 is inserted into a lumen of the sheath 200, the sleeve 220 covers the actuator, the elongated pusher 630 and the dilator body 520. A proximal end of the rigid annular collar 210 is configured to connect to the dilator hub 510. Alternatively, or additionally, the dilator hub 510 and the rigid annular collar 210 may be configured as described with reference to Figures 2 and 3 for securing the dilator 500 to the sheath 200.

[0071] The dilator hub 510 further comprises a button 540 coupled thereto by a biasing element 590 (see Figure 4C) embodied in a spring, which is attached at one end to the button 540 and at the other end to the dilator hub 510. The button 540 and the biasing element 590 are configured to slidably move the dilator body 320 and dilator tip 530 longitudinally and relative to dilator hub 510 to further ensure that the proximal end of the dilator tip 530 abuts the distal end of the sheath 200.

[0072] Figure 4D illustrates an enlarged view of the distal section of the dilator 500 of Figure 4A. Figure 4E provides an enlarged section view of the distal section of the dilator 500 of Figure 4B and 4C, in which the dilator 500 is inserted into the lumen of the sleeve 220 of the sheath 200. The actuator 600 is formed by a single lumen tube 610 that is configured to slide over the elongated dilator body 520. In addition, to the single lumen tube 610, the actuator 600 has a series of flexible arms 620 at the distal end. In the first position, the flexible arms 620 form a first diameter dl of the actuator 600 which is smaller than the interior diameter of the sheath 200. As depicted in Figure 4E a distal end surface of the sheath 222, defined by the thickness of the sleeve 220 at the distal end, abuts a proximal end surface 532 of the dilator tip 530, to provide a more even transition between the sheath 200 and the dilator tip 530.

[0073] Figures 5A to 5E illustrate the dilator 500 and sheath 200 of Figures 4A to 4E with actuator 600 in a second position. It will be understood that all elements of the dilator 500 and sheath 200 described with reference to Figures 4A to 4E are present in the dilator 500 and sheath 200 described with reference to Figures 5A to 5E.

[0074] Figure 5D illustrates an enlarged view of the distal section of the dilator 500 of Figure 5A. Figure 5E illustrates an enlarged section view of the distal section of the dilator 500 of Figure 5B and 5C, in which the dilator 500 is inserted into the sleeve 220 of the sheath 200. After the actuator 600 has slid longitudinally in a direction from the proximal end of the sheath 200 towards the distal end of the sheath 200 a predetermined distance, the actuator 600 adopts a second position. In the second position, the actuator 600 is placed partially over the dilator shoulder 550. The second position is achieved by operating the slider 670, which is pushed distally, causing the elongated pusher 630 to slide over the dilator body 520. This action, in turn, moves the actuator 600 towards the dilator tip 530 and the sleeve’s 220 distal end. As illustrated in Figures 5D and 5E, the single lumen tube 610 of the actuator 600 has slid longitudinally towards the dilator tip 530. The flexible arms 620 are configured to radially expand and slide over a wedge profile 560 of the dilator shoulder 550 to form a second diameter d2 of the actuator 600. Since the second diameter d2 is greater than the first diameter dl and greater than the interior diameter of the sheath 200, the actuator 600 radially expands the distal end of the sheath 200. As illustrated in Figure 5E, it is preferable that the flexible arms 620 align with the dilator shoulder 550 and a distal end surface of the actuator 622, defined by the thickness of the flexible arms 620 at the distal end, abuts the proximal end surface 532 of the dilator tip 530, when the distal end of the sleeve 220 of the sheath 200 is expanded. This provides an optimal positioning of the actuator 600 to expand the distal end of the sleeve 220 and facilitate retraction of the dilator 500 when required.

[0075] Instead of flexible arms, the single lumen tube 610 may be provided with a scroll expander 612 or a buckling element 614 at the distal end, as illustrated in the embodiments of Figures 6 and 7. In case of the scroll expander 612, the radial expansion occurs with a scroll like fashion. When the single lumen tube 610 is pushed forward towards the dilator tip 530, the scroll expander scrolls open along a single stepped slit to create the radial expansion of the sleeve 220 while maintaining a substantially cylindrical overall profile. The buckling element 614 may comprise a tube of rubber like material that sits in front of the single lumen tube 610. When the single lumen tube 610 is moved forwards the buckling element 614 expands over the dilator shoulder 550. Due to the pushing force being applied and the support provided by the dilator shoulder 550, the buckling element can continue to expand.

[0076] Figures 8 to 9D illustrate a dilator 500 according to another embodiment according to the invention. Elements of the dilator 500 and sheath 200 described with reference to the previous embodiments may also be part of the embodiments shown in Figures 8 to 9D. In particular, the main components of the dilator 500 and sheath 200 are essentially the same. Figure 8 illustrates a section view of the dilator 500 inserted into the sheath 200. Like previous embodiments, the dilator 500 comprises a dilator tip 530, an elongated dilator body 520 coupled to the dilator tip 530 and a dilator hub 510. The dilator body 520 is coupled to the dilator tip 530 on a distal end and to the dilator hub 510 on the proximal end. The distal end of the sleeve 220 of the introducer sheath 200 is in contact with the dilator tip 530. The diameter of the dilator body 520 is smaller than the diameter of the proximal end of the dilator tip 530. The dilator 500 further comprises a dilator lumen 570 extending throughout a length of the dilator 500. The sheath 200 comprises a rigid annular collar 210 and a sleeve 220. Like the introducer sheath assembly described with reference to Figures 1 to 3, the dilator tip 530 has a tapered head that is substantially conical, and has a maximum diameter at its proximal end, where it is configured to contact a distal end of the sheath 2OO.The actuator 700 is formed by a ring 710, which is configured to slide over the dilator body 520. The ring 710 has an exterior diameter similar to the diameter of the proximal end of the dilator tip 530 and greater than the interior diameter of the sleeve 220 of the sheath 200 before expansion. The ring 710 is configured to longitudinally slide within the sleeve 220 from a proximal position within the sheath 200 to a distal position near the proximal end of the dilator tip 530. As illustrated in Figures 9A and 9B, the ring 710 may be a segmented ring. As illustrated in Figures 9C and 9D, the ring 710 may be a solid ring.

[0077] The ring 710 may be introduced into the sleeve 420 of the sheath 200 from a proximal end and, for example, by the aid of the rigid annular collar 210. When the ring 710 is pushed forward from a position near the proximal end towards the dilator tip 530, the ring 710 will engage the inner surface of the sleeve 220 and create a radial expansion of the sleeve 220. The ring 710 is connected to a distal end of an elongated pusher 730 that is placed over the dilator body 520. The elongated pusher 730 is configured to push the ring 710 distally through the lumen of the sleeve 220. The dilator hub 510 includes an operation ring 770 coupled to a proximal end of the elongated pusher 730 configured to operate the ring 710. The ring 710 may radially expand the sheath 200 while it is being push distally over the dilator body 520. Particularly, the ring 710 may radially expand the distal end of the sheath 200 while still allowing retraction of the dilator tip 530 and the ring 710, through the sleeve 220. The elongated pusher 730 may comprise a continuous cylinder, as illustrated in Figures 4A and 5A or a plurality of elongated members arranged in a cylindrical configuration as illustrated in Figures 9A to 9D.

[0078] A dilator 500 according to any of the embodiments described hereinabove may be manufactured in the same manner in all embodiments. For instance, the dilator tip 530 may be manufactured through processes such as injection moulding or thermoforming using RF energy or hot air and / or it may comprise a biocompatible polymer of shore hardness 25 A to 100D. Suitable biocompatible polymers are Pebax, Polyurethane, Polyethylene, Nylon, Polypropylene, Styrenic polymers, biocompatible elastomers, or combinations thereof. The dilator tip 530 may be reinforced with a metallic or polymer wire, braid, or coil for improved rigidity. The dilator tip 530 may also be coated with a lubricant film or lubricious coating to reduce the force required to gain passage through the patient tissue. The dilator body 520 may comprise an extruded biocompatible polymer material and cut to the required length . The dilator shoulder 550 may comprise the same material as the dilator tip 530 or it may comprise another of the biocompatible polymers mentioned above. The dilator shoulder 550 may also comprise a material that increases visibility of a distal section of the dilator 500 under X-ray viewing, for example stainless steel, titanium, or other metal, which may also be arranged to reinforce the dilator shoulder 550. The dilator shoulder 550 may be formed integrally with the dilator tip 530 and / or dilator body 520. Alternatively, the dilator shoulder 550 may be manufactured separately and assembled, bonded, or otherwise affixed to either or both the dilator body 520 and dilator tip 530. The dilator body 520 may be manufactured from an extruded biocompatible polymer like that of the dilator tip 530 or dilator body 520, and it may also be reinforced with a metal or polymer coil or braid to improve pushability and / or rigidity for passage through the patient tissue.

[0079] The actuator 600, 700 and the elongated pusher 630, 730 may comprise a biocompatible material with sufficient rigidity to resist the compression load applied during radially expansion and / or longitudinally sliding within the sheath 200 and to expand the distal end of the sheath 200. Biocompatible materials may include polymers such as nylon, polypropylene, polyethylene, and polyurethane, fluoropolymers, or metals such as stainless steel, spring steels, titanium, their alloys, and composite materials. Similarly, the scroll expander 612 and buckling element 614 illustrated in Figure 6 and Figure 7 may comprise a resilient biocompatible material and may include any of the polymers or metallic materials mentioned above. A method of manufacturing a dilator, in particular a dilator as illustrated in Figures 4A to 5E may include one or more of the steps of: extruding a biocompatible polymer material and cutting the extruded material to a required length to form a dilator body; optionally, overmoulding a button onto the dilator body by an insert moulding process and placing a bias element, such as a spring, into a dilator hub and over the dilator body; extruding a biocompatible polymer tube and cutting the extruded tube to a predetermined length to form a single lumen tube, the single lumen tube having a suitable diameter and length to easily slide over the dilator body; forming longitudinal cuts at a distal end of the single lumen tube to obtain flexible arms of the single lumen tube; moulding an elongated pusher onto the single lumen tube preferably through an insert injection moulding process; placing the single lumen tube onto the dilator body; moulding the dilator tip, and optionally a dilator shoulder, onto the dilator body through an insert injection moulding process; softening the material of a distal area of the dilator tip and pushing the distal area into a die, thereby forming a substantially conical or arrowhead shape of the dilator tip.

[0080] The dilator hub may be formed by injection moulding. For instance, the dilator hub may be formed by two rigid annular structures, with a first structure having an exterior diameter similar to an internal diameter of a second structure, such as the first structure is arranged to tightly fit into the second structure. A dilator subassembly may include the dilator body, dilator tip, actuator, and spring, which may be further assembled to the dilator hub which may incorporate fasteners, clips, welded or otherwise bonded joints to attach to the dilator body.

[0081] A method of operating an introducer sheath assembly according to any of the described embodiments may include one or more of the steps of: flushing the dilator lumen and sheath lumen with saline solution; inserting the dilator into the sheath through the rigid annular collar of the sheath up until the dilator hub abuts the rigid annular collar and with the actuator in the first position; securing the dilator hub to the rigid annular collar; optionally, pushing the dilator button to advance the dilator tip through the distal end of the sheath; radially expand and / or longitudinally slide the actuator in a direction from the proximal end of the sheath towards the distal end of the sheath to expand the distal end of the sheath; and retract the dilator until it has been removed from the sheath.

Claims

Claims1. An introducer sheath assembly, comprising: a sheath having a distal end, a proximal end, an interior diameter, an exterior diameter, a lumen, and a length extending from the distal end to the proximal end, the sheath being configured to be inserted into the patient’s vasculature and to expand in a direction radially outward from the lumen, a dilator comprising: a dilator tip being configured to abut to and extend from the distal end of the sheath; and an elongated dilator body coupled to the dilator tip and extending through the lumen of the sheath, and an actuator being configured to slide within the lumen in a direction from the proximal end of the sheath towards the distal end of the sheath to expand the sheath in a direction radially outward from the lumen, and wherein the actuator is configured to radially expand and / or move longitudinally such that the interior diameter of the distal end of the sheath is increased.

2. The introducer sheath assembly according to claim 1, wherein the actuator is coupled to the dilator and configured to move from a first position in which the actuator has a first diameter smaller than the interior diameter of the sheath to a second position in which the actuator has a second diameter that is greater than the first diameter and greater than the interior diameter of the sheath before expansion.

3. The introducer sheath assembly according to claim 2, wherein the actuator is positioned between the dilator body and the dilator tip, and wherein the actuator is configured to radially expand from the first position in which the actuator has the first diameter to the second position in which the actuator has the second diameter such that the interior diameter of the distal end of the sheath is increased.

4. The introducer sheath assembly according to claim 3, wherein the actuator comprises a coiled, clock spring like element.

5. The introducer sheath according to claim 3 or claim 4, further comprising a cover configured to be pulled back proximally by a user to allow the actuator to expand to a set diameter which expands the distal end of the sheath.

6. The introducer sheath assembly according to claim 2, wherein the dilator further comprises a dilator shoulder positioned between the dilator body and the dilator tip, wherein the dilator shoulder has an exterior diameter that is greater than an exterior diameter of the dilator body and smaller than the interior diameter of the sheath before expansion; and wherein the actuator is configured to slide from the dilator body to the dilator shoulder to move from the first position to the second position such that the interior diameter of the distal end of the sheath is increased to the second diameter.

7. The introducer sheath assembly according to claim 6, wherein a distal end of the actuator is configured to expand from the first diameter to the second diameter when the actuator is moved from the dilator body to the dilator shoulder.

8. The introducer sheath assembly according to claim 6 or claim 7, wherein the dilator shoulder comprises a wedge profile providing gradual transition from the dilator body to the dilator shoulder, and wherein the distal end of the actuator is configured to expand radially outward to the second diameter by engaging the wedge profile when the actuator is moved from the dilator body to the dilator shoulder.

9. The introducer sheath according to any one of the claims 6 to 8, wherein the actuator is formed by a single lumen tube with a series of flexible arms at the distal end of the single lumen tube.

10. The introducer sheath assembly according to any one of the claims 6 to 8, wherein the actuator is formed by a single lumen tube with a scroll expander, a buckling expander, or mated C-profiles at the distal end of the single lumen tube.

11. The introducer sheath assembly according to claim 1, wherein the actuator has an exterior diameter approximately equal to the exterior diameter of a proximal end of the dilator tip and greater than the interior diameter of the sheath before expansion, and wherein the actuator is configured to move from a proximal position within the sheath to a distal position near the dilator tip.

12. The introducer sheath assembly according to claim 11, wherein the actuator is formed by a solid ring or a segmented ring.

13. The introducer sheath assembly according to any one of the preceding claims, wherein the dilator body has an exterior diameter smaller than the exterior diameter of the proximal end of the dilator tip, optionally, the dilator tip comprises a tapered head that is substantially conical, and wherein at a proximal end, the tapered head tapers outward from the distal end of the dilator body at an interface between the dilator body and the tapered head, to a maximum diameter of the tapered head, and tapers inward from the maximum diameter of tapered head to a rounded apex at the distal end of tapered head.

14. The introducer sheath assembly according to any one of the preceding claims, further comprising an elongated pusher configured to push the actuator distally through the lumen of the sheath.

15. The introducer sheath assembly according to any one of the preceding claims, wherein the dilator further comprises a dilator hub at its proximal end.

16. The introducer sheath according to claim 14 in combination with claim 15, wherein the elongated pusher extends longitudinally from the dilator hub to the actuator.

17. The introducer sheath assembly according to claim 16, wherein the hub comprises a slider connected to the elongated pusher and configured to allow a user to operate the elongated pusher.

18. The introducer sheath assembly according to any one of the claims 14-17, wherein the elongated pusher comprises a continuous cylinder or a plurality of elongated members arranged in a cylindrical configuration.

19. The introducer sheath assembly according to any one of claims 15-18, 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 sheath.

20. The introducer sheath assembly according to claim 19, wherein the dilator hub further comprises 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.

21. The introducer sheath assembly according to claim 20, wherein the sheath further comprises a securement fitting configured for receiving the securing means of the dilator hub and securing the dilator thereto.

22. The introducer sheath assembly according to any one of the proceeding claims, wherein the sheath comprises a dual layer sleeve including a continuous elastomeric outer layer and an expandable inner layer discontinuous at least in part, and wherein the dilator tip is configured to at least abut to and extend from the distal end of the continuous elastomeric outer layer.

23. The introducer sheath assembly according to any one of the proceeding claims, wherein the sheath is longitudinally tapered at least partially between the proximal end and the distal end of the sheath.

24. An introducer sheath assembly comprising: an introducer sheath having a lumen extending from a distal end to a proximal end, the sheath being configured to be inserted into a patient, a dilator configured to be inserted into the introducer sheath, the dilator comprising:an elongated dilator body extending through the lumen of the sheath, and a dilator tip coupled to the dilator body and configured to extend outside the sheath from the distal end of the sheath, and an actuator configured to slide over the dilator body and configured to radially expand the distal end of the sheath by radially expanding within the lumen of the sheath and / or longitudinally sliding in a direction from the proximal end of the sheath towards the distal end of the sheath.

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