Vented medical device

Abstract

A vascular access kit includes a sheath (12) and dilator (14). The sheath has a shaft with a hemostatically-sealed proximal hub and lumen. The dilator has a dilator shaft (20) and a head (42) attached to the distal end of the dilator shaft. The head includes a cylindrical proximal portion (44) and a tapered distal portion (46), as well as at least one channel (48) extending longitudinally along an outer wall of the proximal portion. If the outer diameter of the cylindrical proximal portion of the head is approximately equal to the sheath lumen diameter, it will create a pressure seal between the head and the sheath; the channel allows fluid (e.g., blood) to pass this pressure seal, thus mitigating negative pressure transients that may form on the distal side of the head as the dilator is withdrawn from the sheath.

Description

Attorney Docket No. 15861WOO1 / 82410.1249VENTED MEDICAL DEVICECROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of United States provisional application no. 63 / 685,344, filed 21 August 2024, which is hereby incorporated by reference as though fully set forth herein.FIELD

[0002] The present disclosure relates generally to medical procedures that involve introducing interventional medical devices into a patient’s vasculature through an introducer. In particular, the instant disclosure relates to regulating pressure in a fluid, such as blood, that may become trapped between an interventional medical device and an introducer as the interventional medical device moves through the introducer.BACKGROUND

[0003] A variety of cardiovascular procedures, such as electrophysiology (EP) mapping and ablation, delivery and implantation of implantable cardioverter defibrillator (ICD) leads, percutaneous transluminal coronary angiography (PTCA), angioplasty, and the like, require vascular access for corresponding interventional medical devices (e.g., EP catheters, ICD leads, PTCA balloon catheters, etc.). Several techniques for introducing such devices into a patient’s vasculature, such as the cut-down method and the Seidinger technique, are known.

[0004] The Seidinger technique involves surgically opening a vasculature of a patient with a relatively small incision and a needle, followed by inserting a guidewire into the vein or artery through the lumen of the needle. After removing the needle, an introducer (sometimes also referred to as a “sheath” or “introducer sheath”) can be inserted over the directing guidewire, followed by the advancement of the introducer along the guidewire into the vasculature until the distal end of the introducer reaches the target location of the vasculature or anatomical structure (e.g, the heart) for an intended medical procedure. Steerable introducers, such as the Agilis™ NxT steerable introducer (Abbott Laboratories; Abbott Park, Illinois), which can be advanced through the vasculature without the use of a guidewire, are also known.Attorney Docket No. 15861WOO1 / 82410.1249

[0005] In any event, the central lumen of the introducer establishes a safe passageway of access to the blood vessel or anatomical structure, thus allowing for repetitive insertion and withdrawal of various interventional medical devices into and from the patient’s vasculature. To minimize blood loss or leakage from the introducer, and to reduce the risk of introducing air, introducers typically include a hub (or “cannula”) incorporating a hemostasis valve system at their proximal end. The hemostasis valve system typically includes one or more valve gaskets contained within a housing.

[0006] Those of skill in the art will appreciate that, as the interventional medical device moves through the lumen of the introducer, it can create a plunger effect, where the pressure on one side of the leading edge of the interventional medical device differs from the pressure on the opposite side of the leading edge of the interventional medical device (in this context, the term “leading edge” refers to the distal end of the interventional medical device). For instance, as the interventional medical device is advanced into the introducer, the pressure ahead of the leading edge (e.g, distal of the distal end of the interventional medical device) may be higher than the pressure behind the leading edge (e.g, proximal of the distal end of the interventional medical device). Conversely, as the interventional medical device is withdrawn from the introducer, the pressure ahead of the leading edge (e.g, distal of the distal end of the interventional medical device) may be lower than the pressure behind the leading edge (e.g., proximal of the distal end of the interventional medical device).BRIEF SUMMARY

[0007] Disclosed herein is a dilator including: a dilator shaft having a distal end and a proximal end; a dilator head attached to the distal end of the dilator shaft, wherein the dilator head includes a cylindrical proximal portion having an outer diameter that is greater than an outer diameter of the dilator shaft and a tapered distal portion; and at least one channel extending longitudinally along an outer wall of the cylindrical proximal portion of the dilator head. The dilator shaft may be an elongate shaft.

[0008] The at least one channel extending longitudinally along the outer wall of the cylindrical proximal portion of the dilator head may include two channels extending longitudinally along the outer wall of the cylindrical proximal portion of the dilator head. TheAttorney Docket No. 15861WOO1 / 82410.1249 two channels may be diametrically opposed to each other about the outer wall of the cylindrical proximal portion of the dilator head.

[0009] The at least one channel may extend longitudinally into the tapered distal portion of the dilator head. The at least one channel may extend longitudinally along a portion of the outer wall of the tapered distal portion of the dilator head.

[0010] The at least one channel can have a depth of up to about 0.008” (0.020cm).

[0011] A dilator hub may be attached to the proximal end of the dilator shaft.

[0012] Also disclosed herein is a kit for access to a patient’s vasculature. The kit includes a sheath comprising: a shaft having a proximal end and a distal end and defining a lumen extending through the shaft, the lumen having a lumen diameter; and a sheath hub attached to the proximal end of the shaft, the sheath hub comprising a hemostasis valve assembly configured to hemostatically seal the lumen. The kit further includes a dilator including: a dilator shaft having a distal end and a proximal end; a dilator head attached to the distal end of the dilator shaft, wherein the dilator head includes a cylindrical proximal portion having an outer diameter that is greater than an outer diameter of the dilator shaft and a tapered distal portion; and at least one channel extending longitudinally along an outer wall of the cylindrical proximal portion of the dilator head. The dilator shaft may be an elongate shaft.

[0013] It is contemplated that the outer diameter of the cylindrical proximal portion of the dilator head is approximately equal to the lumen diameter. The lumen cross-section may be circular or non-circular. The term “diameter” as used herein is intended to mean the maximum dimension of the cross-section, regardless of whether the cross-section is circular or some other shape (non-circular).

[0014] The at least one channel extending longitudinally along the outer wall of the cylindrical proximal portion of the dilator head may include two channels extending longitudinally along the outer wall of the cylindrical proximal portion of the dilator head, which may be diametrically opposed to each other about the outer wall of the cylindrical proximal portion of the dilator head. The at least one channel may also extend longitudinally into the tapered distal portion of the dilator head. The at least one channel may extend longitudinally along a portion of the outer wall of the tapered distal portion of the dilator head.Attorney Docket No. 15861WOO1 / 82410.1249

[0015] According to aspects disclosed herein, the at least one channel has a depth of up to about 0.008” (0.020cm).

[0016] A dilator hub may be attached to the proximal end of the dilator shaft.

[0017] The instant disclosure also provides a method of regulating pressure differentials resulting from proximal movement of an elongate medical device through a lumen of a sheath having a hemostatic seal by facilitating flow of a fluid trapped within the sheath between the elongate medical device and the hemostatic seal of the sheath distally past an outer wall of the elongate medical device by forming at least one channel extending longitudinally along the outer wall of the elongate medical device.

[0018] Forming the at least one channel extending longitudinally along the outer wall of the elongate medical device may include forming two channels extending longitudinally along the outer wall of the elongate medical device; the two channels may be diametrically opposed to each other about the outer wall of the elongate medical device. The at least one channel may also extend longitudinally into the tapered distal portion of the dilator head and may have a depth of up to about 0.008” (0.020cm).

[0019] The elongate medical device may be a dilator including a dilator shaft having a distal end and a proximal end and a dilator head attached to the distal end of the dilator shaft.The dilator head may include a cylindrical proximal portion having an outer diameter that is greater than an outer diameter of the dilator shaft and a tapered distal portion, and wherein the at least one channel extends longitudinally along an outer wall of the dilator head. An outer diameter of the elongate medical device may be approximately equal to a diameter of the lumen of the sheath.

[0020] The instant disclosure also provides a use of the kit in a method of regulating pressure differentials resulting from proximal movement of an elongate medical device through the lumen having a hemostatic seal. The at least one channel extending longitudinally along the outer wall of the elongate medical device may facilitate flow of a fluid trapped within the sheath between the elongate medical device and the hemostatic seal of the sheath distally past an outer wall of the elongate medical device.

[0021] A channel may advantageously act as a vent to mitigate both the potential for escape of fluid through a hemostasis seal and negative pressure transients on the distal side of theAttorney Docket No. 15861WOO1 / 82410.1249 elongate medical device by allowing fluid to escape distally as the elongate medical device is withdrawn proximally. This escape of fluid may both regulate the pressure of fluid, preventing pressure buildup between the hemostasis seal and elongate medical device, and minimize negative pressure transients behind the moving elongate medical device.

[0022] The foregoing and other aspects, features, details, utilities, and advantages of the present invention will be apparent from reading the following description and claims, and from reviewing the accompanying drawings.BRIEF DESCRIPTION OF THE DRAWINGS

[0023] This written disclosure is further illustrated with reference to the following figures, in which:

[0024] Figure 1 illustrates representative elements of a kit for accessing a patient’s vasculature according to aspects of the present disclosure.

[0025] Figure 2 is a side, partially cut-away view illustration of the Seidinger technique for vascular access.

[0026] Figure 3 is a cross-sectional view of a representative introducer comprising a hub within which an integral hemostasis valve system is disposed.

[0027] Figure 4 is a close-up view of the distal end of a dilator.

[0028] Figure 5 is a cross-sectional view of the cylindrical proximal portion of the dilator head shown in Figure 4.

[0029] Figure 6 illustrates use of the kit of Figure 1.

[0030] While multiple dilators and kits are disclosed, still other examples of the present disclosure will become apparent to those skilled in the art from the following detailed description, which shows and describes illustrative examples. Accordingly, the drawings and detailed description are to be regarded as illustrative in nature and not restrictive.DETAILED DESCRIPTION

[0031] The instant disclosure provides apparatus and methods for regulating pressure buildup in a fluid, such as blood, during an interventional medical procedure where two devices are moving relative to each other in a manner that diminishes the physical volume occupied byAttorney Docket No. 15861WOO1 / 82410.1249 the fluid. For purposes of illustration, aspects of the disclosure will be described with reference to the introduction of a medical device, such as a dilator, into a patient’s vasculature using an introducer sheath. Those of ordinary skill in the art, however, will appreciate that the instant teachings may be applied to good advantage in other contexts.

[0032] Referring now to the drawings, Figure 1 illustrates various elements of a representative kit 10 for access to a patient’s vasculature, including an introducer (or sheath) 12 and a dilator 14. Insofar as the construction of introducer 12 will be familiar to those of ordinary skill in the art, it will only be discussed herein to the extent necessary to understand the instant disclosure. By way of example only, however, introducer 12 may be the Agilis™ NxT Steerable Introducer (Abbott Laboratories; Abbott Park, Illinois).

[0033] Many aspects of the structure of dilator 14 will also be familiar to those of ordinary skill in the art. Accordingly, dilator 14 will be described herein only to the extent necessary to understand the instant disclosure.

[0034] As shown in Figure 1, dilator 14 generally includes a shaft (or body) 20 having a proximal end 16 and a distal end 18. Dilator shaft 20 can be provided in various outer diameters (e.g., French size), in various lengths, and / or with various preset or adjustable curvatures of distal end 18, as may be desirable for any particular application of dilator 14. Dilator shaft 20 may be elongate. Accordingly, the specific dimensions and shapes of dilator 14 depicted and described herein are intended to be exemplary and illustrative rather than limiting. Indeed, those of ordinary skill in the art will appreciate that various modifications can be made thereto without departing from the scope of the instant disclosure.

[0035] Likewise, various materials suitable for use in the construction of shaft 20 of dilator 14 will be known to those of ordinary skill in the art. By way of illustration only, however, such materials include, without limitation, various nylon polymers (e.g., Nylon 12), polyeteher block amide elastomers in various durometers e.g., PEBAX 72D (Arkema Inc.; King of Prussia, Pennsylvania), high-density polyethylene (HDPE), and other thermoplastics.

[0036] It is further contemplated that shaft 20 may combine sections of different materials. These sections may be arranged in layers, such as by co-extrusion, and / or in abutment along the length of dilator shaft 20. As but one example, the majority of dilator shaft 20 may be made of Nylon 12, while a dilator head 42 attached to distal end 18 of dilator shaft 20 (discussed inAttorney Docket No. 15861WOO1 / 82410.1249 further detail below) may be made of PEBAX 72D. This configuration is advantageous insofar as Nylon 12 is stiffer and can improve pushability of dilator shaft 20, while PEBAX 72D is softer and renders the dilator head 42 more compliant to pass through and / or be deflected by introducer 12.

[0037] A dilator hub 22, which will be familiar to the ordinarily-skilled artisan, may be attached to proximal end 16 of dilator shaft 20. Amongst other functions, dilator hub 22 can be used to deliver irrigation to dilator 14, in particular to the distal end 18 of dilator shaft 20, and / or for aspiration thereof. Further, a hemostasis valve adapter including a Luer lock fitting can be attached to dilator hub 22.

[0038] Figure 2 depicts the introduction of various medical devices, including guidewire 24, introducer 12, and dilator 14, into a blood vessel 26 using the Seidinger technique. Insofar as the ordinarily-skilled artisan will be familiar with the Seidinger technique, it need not be described in further detail herein. Likewise, those of ordinary skill in the art will be familiar with other approaches to introducing medical devices into blood vessel 26, including the use of steerable introducers.

[0039] As Figure 3 illustrates, introducer (or sheath) 12 includes a shaft 13 that defines a lumen 15 extending through the shaft. The shaft 13 has a proximal end and a distal end.Introducer 12 also includes a sheath hub 28 attached to the proximal end of shaft 13 and including a hemostasis valve assembly 30. Introducer 12 includes a side-port fluid tubing 32 with an associated stopcock assembly 34. As shown in Figure 3, sheath hub 28 includes a cap 36 and a housing 38 circumferentially sealed together, within which integral hemostasis valve assembly 30 (including, by way of example only, two hemostasis valve gaskets 30a, 30b) is disposed at its proximal end. Side-port fluid tubing 32 and associated stopcock assembly 34 are also coupled to hub 28 or housing 38 to enable the introduction of medical fluids (e.g., saline) through introducer 12 for an intended clinical procedure.

[0040] Figure 3 is a cross-sectional view of introducer 12 incorporating integral hemostasis valve assembly 30 within a circumferentially-sealed hub 28. Various details of hub 28, including housing 38 and cap 36, will be familiar to those of ordinary skill in the art; thus, hub 28 will only be described herein to the extent necessary to understand the instant disclosure.Attorney Docket No. 15861WOO1 / 82410.1249

[0041] The exterior of hub 28 is defined by housing 38 and cap 36. Cap 36 defines an aperture 40 into housing 38 (e.g., an opening through which various interventional medical devices, including dilator 14, may be inserted through hub 28, into lumen 15 of introducer 12, and thus into blood vessel 26).

[0042] Contained within circumferentially sealed housing 38 by cap 36 are one or more hemostasis valve gaskets, such as a first (or proximal) valve gasket 30a and a second (or distal) valve gasket 30b as described in International Patent Application Publication No.WO 2022 / 245598, which is hereby incorporated by reference as though fully set forth herein. Of course, other hemostasis valve gasket configurations and arrangements are regarded as within the scope of the present disclosure, and the foregoing reference is merely exemplary rather than limiting. As fully assembled and constrained within housing 38, first and second valve gaskets 30a, 30b may be collectively referred to as a hemostasis valve assembly 30.

[0043] Figure 4 is a close-up view of distal end of dilator 14 showing a dilator head 42 attached to distal end 18 of dilator shaft 20. Dilator head 42 includes a cylindrical proximal portion 44 and a tapered distal portion 46. As used herein, the term “cylindrical” is not limited to right circular cylinders (such as shown in Figure 4), but rather is intended to encompass other shapes, such as cylinders that taper, flare, or otherwise vary in cross-sectional dimension along their height (or, as oriented in Figure 4, along their length). As discussed above, the term “diameter” as used herein is intended to mean the maximum dimension of the cross-section, regardless of whether the cross-section is circular or some other shape (non-circular). The diameter of the dilator head may be measured using a micrometer.

[0044] As shown to good advantage in Figure 4, cylindrical proximal portion 44 of dilator head 42 has an outer diameter greater than the outer diameter of dilator shaft 20. For instance, dilator shaft 20 can have a diameter of about 10 French, while cylindrical proximal portion 44 of dilator head 42 can have a diameter of about 13 French. It should be understood, however, that these dimensions are merely illustrative and may be varied without departing from the scope of the instant disclosure.

[0045] At least one channel 48 may extend longitudinally along the outer surface (or outer wall) of cylindrical proximal portion 44 of dilator head 42. and may also extend into tapered distal portion 46 of dilator head 42. That is, the at least one channel 48 may extend longitudinallyAttorney Docket No. 15861WOO1 / 82410.1249 along a proximal portion of the outer wall (or outer surface) of the tapered distal portion 46 of the dilator head 42.

[0046] As shown in the cross-sectional view of Figure 5, embodiments of dilator head 42 can include two channels 48 that are diametrically opposed to each other about the circumference of the outer wall (or outer surface) of cylindrical proximal portion 44. Channels 48 may have a semi-circular profile and a depth into the outer wall of cylindrical proximal portion of up to about 0.008” (0.020cm). Once again, however, it should be understood that the quantity, placement, shape, and dimensions of channels 48 illustrated herein are merely exemplary and may be varied without departing from the scope of the instant disclosure. For instance, in other embodiments, channels 48 may have a rectangular profile; in still further embodiments, they may have a depth into the outer wall of cylindrical proximal portion of up to about 0.04” (0.10cm).

[0047] Operation of kit 10 is further illustrated in Figure 6. In Figure 6, dilator 14 is shown inserted into lumen 15 of introducer 12. As shown in Figure 6, the outer diameter of cylindrical proximal portion 44 of dilator head 42 may be approximately equal to the diameter of lumen 15. As used herein, the phrase “approximately equal” means that the dimensional tolerances between the maximum outer diameter of cylindrical proximal portion 44 of dilator head 42 and the diameter of lumen 15 are sufficiently close to create an effective pressure seal between the outer surface of cylindrical proximal portion 44 at its maximum outer diameter and the inner surface of shaft 13. The diameter of lumen 15 may be measured using a micrometer.

[0048] Thus, because lumen 15 is hemostatically sealed by hemostasis valve assembly 30 and an effective pressure seal exists between cylindrical proximal portion 44 of dilator head 42 and shaft 13, a quantity of blood 50 (which can enter lumen 15 when dilator head 42 is fully advanced out of introducer 12, such as during a transseptal puncture) can become trapped between hemostasis valve assembly 30 and dilator head 42. As dilator 14 is withdrawn proximally (in the direction of arrow W in Figure 6), the volume occupied by blood 50 begins to diminish, thus increasing the pressure of blood 50. If this pressure is allowed to continue to increase, it could ultimately exceed the ability of hemostasis valve assembly 30 to maintain hemostasis, which would allow blood 50 to escape introducer 12 through hemostasis valve assembly 30.Attorney Docket No. 15861WOO1 / 82410.1249

[0049] Similarly, as dilator 14 is withdrawn proximally (in the direction of arrow W in Figure 6), it can create a plunger effect that results in a pressure differential across the dilator head 42, where the pressure ahead of the leading edge of dilator head 42 (e.g, the proximal side of dilator head 42, towards blood 50) may be higher than the pressure behind the leading edge of dilator head 42 (c'.g, the distal side of dilator head 42, towards the patient’s vasculature). This can create a negative pressure transient, as discussed in further detail in United States provisional application no. 63 / 610,636, which is hereby incorporated by reference as though fully set forth herein.

[0050] Channel(s) 48 acts as a vent to mitigate both the potential for escape of blood 50 through hemostasis valve assembly 30 and negative pressure transients on the distal side of dilator head 42 by allowing blood 50 to escape distally (e.g, back into the patient’s vasculature) as dilator 14 is withdrawn proximally. This escape of blood 50 both regulates the pressure of blood 50, preventing pressure buildup between hemostasis valve assembly 30 and dilator head 42, and minimizes negative pressure transients behind the moving dilator head 42.

[0051] Although several examples have been described above with a certain degree of particularity, those skilled in the art could make numerous alterations to the disclosed dilator and kit without departing from the spirit or scope of this invention.

[0052] For example, it is also contemplated that the outer diameter of cylindrical proximal portion 44 of dilator head 42 may be sufficiently smaller than the diameter of lumen 15 to allow blood 50 to escape distally (e.g, back into the patient’s vasculature) between dilator head 42 and the inner surface of shaft 13 as dilator 14 is withdrawn proximally without aid of channels 48.

[0053] All directional references (e.g, upper, lower, upward, downward, left, right, leftward, rightward, top, bottom, above, below, vertical, horizontal, clockwise, and counterclockwise) are only used for identification purposes to aid the reader’s understanding of the present invention, and do not create limitations, particularly as to the position, orientation, or use of the invention. Joinder references (e.g., attached, coupled, connected, and the like) are to be construed broadly and may include intermediate members between a connection of elements and relative movement between elements. As such, joinder references do not necessarily infer that two elements are directly connected and in fixed relation to each other.Attorney Docket No. 15861WOO1 / 82410.1249

[0054] It is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative only and not limiting. Changes in detail or structure may be made without departing from the spirit of the invention as defined in the appended claims.

[0055] The following are numbered aspects of the invention:

[0056] Aspect 1. A dilator, comprising: a dilator shaft having a distal end and a proximal end; a dilator head attached to the distal end of the dilator shaft, wherein the dilator head includes a cylindrical proximal portion having an outer diameter that is greater than an outer diameter of the dilator shaft and a tapered distal portion; and at least one channel extending longitudinally along an outer wall of the cylindrical proximal portion of the dilator head.

[0057] Aspect 2. The dilator according to aspect 1, wherein the at least one channel extending longitudinally along the outer wall of the cylindrical proximal portion of the dilator head comprises two channels extending longitudinally along the outer wall of the cylindrical proximal portion of the dilator head.

[0058] Aspect 3. The dilator according to aspect 2, wherein the two channels are diametrically opposed to each other about the outer wall of the cylindrical proximal portion of the dilator head.

[0059] Aspect 4. The dilator according to any of aspects 1 to 3, wherein the at least one channel extends longitudinally into the tapered distal portion of the dilator head.

[0060] Aspect 5. The dilator according to any of aspects 1 to 4, wherein the at least one channel has a depth of up to 0.008” (0.020cm).

[0061] Aspect 6. The dilator according to any of aspects 1 to 5, further comprising a dilator hub attached to the proximal end of the dilator shaft.

[0062] Aspect 7. A kit for access to a patient’s vasculature, comprising: a sheath, comprising: a shaft having a proximal end and a distal end and defining a lumen extending through the shaft, the lumen having a lumen diameter; and a sheath hub attached to the proximal end of the shaft, the sheath hub comprising a hemostasis valve assembly configured to hemostatically seal the lumen; and a dilator according to any of aspects 1 to 6.

[0063] Aspect 8. The kit according to aspect 7, wherein the outer diameter of the cylindrical proximal portion of the dilator head is approximately equal to the lumen diameter.Attorney Docket No. 15861WOO1 / 82410.1249

[0064] Aspect 9. A method of regulating pressure differentials resulting from proximal movement of an elongate medical device through a lumen of a sheath having a hemostatic seal, comprising: facilitating flow of a fluid trapped between the elongate medical device and the hemostatic seal of the sheath distally past an outer wall of the elongate medical device by forming at least one channel extending longitudinally along the outer wall of the elongate medical device.

[0065] Aspect 10. The method according to aspect 9, wherein forming the at least one channel extending longitudinally along the outer wall of the elongate medical device comprises forming two channels extending longitudinally along the outer wall of the elongate medical device, wherein the two channels are diametrically opposed to each other about the outer wall of the elongate medical device.

[0066] Aspect 11. The method according to aspect 9, wherein the elongate medical device comprises a dilator according to any of aspects 1 to 6.

[0067] Aspect 12. The method according to any of aspects 9 to 11, wherein an outer diameter of the elongate medical device is approximately equal to a diameter of the lumen of the sheath.

[0068] Aspect 13. The method according to any of aspects 9 to 12, wherein the at least one channel has a depth of up to 0.008” (0.020cm).

[0069] Aspect 14. Use of a kit according to aspect 7 or 8 in a method of regulating pressure differentials resulting from proximal movement of an elongate medical device through the lumen having a hemostatic seal, wherein the at least one channel extending longitudinally along the outer wall of the elongate medical device facilitates flow of a fluid trapped between the elongate medical device and the hemostatic seal of the sheath distally past an outer wall of the elongate medical device.

Claims

Attorney Docket No. 15861WOO1 / 82410.1249CLAIMSWhat is claimed is:

1. A dilator, comprising: a dilator shaft having a distal end and a proximal end; a dilator head attached to the distal end of the dilator shaft, wherein the dilator head includes a cylindrical proximal portion having an outer diameter that is greater than an outer diameter of the dilator shaft and a tapered distal portion; and at least one channel extending longitudinally along an outer wall of the cylindrical proximal portion of the dilator head.

2. The dilator according to claim 1, wherein the at least one channel extending longitudinally along the outer wall of the cylindrical proximal portion of the dilator head comprises two channels extending longitudinally along the outer wall of the cylindrical proximal portion of the dilator head.

3. The dilator according to claim 2, wherein the two channels are diametrically opposed to each other about the outer wall of the cylindrical proximal portion of the dilator head.

4. The dilator according to claim 1, wherein the at least one channel extends longitudinally into the tapered distal portion of the dilator head.

5. The dilator according to claim 1, wherein the at least one channel has a depth of up to 0.008” (0.020cm).

6. The dilator according to claim 1, further comprising a dilator hub attached to the proximal end of the dilator shaft.

7. A kit for access to a patient’s vasculature, comprising: a sheath, comprising: a shaft having a proximal end and a distal end and defining a lumen extending through the shaft, the lumen having a lumen diameter; andAttorney Docket No. 15861WOO1 / 82410.1249 a sheath hub attached to the proximal end of the shaft, the sheath hub comprising a hemostasis valve assembly configured to hemostatically seal the lumen; and a dilator, comprising: a dilator shaft having a distal end and a proximal end; a dilator head attached to the distal end of the dilator shaft, wherein the dilator head includes a cylindrical proximal portion having an outer diameter that is greater than an outer diameter of the dilator shaft and a tapered distal portion; and at least one channel extending longitudinally along an outer wall of the cylindrical proximal portion of the dilator head.

8. The kit according to claim 7, wherein the outer diameter of the cylindrical proximal portion of the dilator head is approximately equal to the lumen diameter.

9. The kit according to claim 7, wherein the at least one channel extending longitudinally along the outer wall of the cylindrical proximal portion of the dilator head comprises two channels extending longitudinally along the outer wall of the cylindrical proximal portion of the dilator head.

10. The kit according to claim 9, wherein the two channels are diametrically opposed to each other about the outer wall of the cylindrical proximal portion of the dilator head.

11. The kit according to claim 7, wherein the at least one channel extends longitudinally into the tapered distal portion of the dilator head.

12. The kit according to claim 7, wherein the at least one channel has a depth of up to 0.008” (0.020cm).

13. The kit according to claim 7, further comprising a dilator hub attached to the proximal end of the dilator shaft.

14. A method of regulating pressure differentials resulting from proximal movement of an elongate medical device through a lumen of a sheath having a hemostatic seal, comprising:Attorney Docket No. 15861WOO1 / 82410.1249 facilitating flow of a fluid trapped between the elongate medical device and the hemostatic seal of the sheath distally past an outer wall of the elongate medical device by forming at least one channel extending longitudinally along the outer wall of the elongate medical device.

15. The method according to claim 14, wherein forming the at least one channel extending longitudinally along the outer wall of the elongate medical device comprises forming two channels extending longitudinally along the outer wall of the elongate medical device, wherein the two channels are diametrically opposed to each other about the outer wall of the elongate medical device.

16. The method according to claim 14, wherein the elongate medical device comprises a dilator including a dilator shaft having a distal end and a proximal end and a dilator head attached to the distal end of the elongate shaft, wherein the dilator head includes a cylindrical proximal portion having an outer diameter that is greater than an outer diameter of the elongate shaft and a tapered distal portion, and wherein the at least one channel extends longitudinally along an outer wall of the dilator head.

17. The method according to claim 16, wherein the at least one channel extends longitudinally into the tapered distal portion of the dilator head.

18. The method according to claim 14, wherein an outer diameter of the elongate medical device is approximately equal to a diameter of the lumen of the sheath.

19. The method according to claim 14, wherein the at least one channel has a depth of up to 0.008” (0.020cm).

20. Use of a kit according to claim 7 in a method of regulating pressure differentials resulting from proximal movement of an elongate medical device through the lumen having a hemostatic seal, wherein the at least one channel extending longitudinally along the outer wall of the elongate medical device facilitates flow of a fluid trapped between the elongate medical device and the hemostatic seal of the sheath distally past an outer wall of the elongate medical device.

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