Rotation lock for dilators

Abstract

The dilator (105) includes a dilator shaft defining a lumen for receiving a functional device, such as a puncture device, therethrough. The dilator shaft includes a proximal portion for manipulation by a user and a distal portion for placement within or near the heart. A dilator hub (202) is coupled to the proximal portion of the dilator shaft and includes a rotational coupling structure for coupling to a corresponding hub (206) of the sheath (100).

Description

[Technical Field]

[0001] The present invention relates generally to methods and devices that can be used to administer therapy to a patient. More particularly, the present invention relates to systems and methods for delivering therapeutic devices to the heart. [Background technology]

[0002] Devices currently exist for creating punctures, channels, or perforations in tissue within a patient's body. One such device is the Brockenbrough™ needle, which is commonly used to puncture the atrial septum of the heart. This device is a rigid, elongated needle that is introduced into the patient's body via the femoral vein and directed toward the heart. This device relies on the use of mechanical force to pass a sharp tip through the septum. Alternatively, radiofrequency perforation devices have been developed whereby septal perforation is achieved by applying focused radiofrequency energy to the septal tissue via an electrode at the distal end of a relatively thin, conductive probe.

[0003] Such drilling devices are often used in conjunction with a dilator to help support and guide the drilling device, and such dilators are often used in combination with a treatment sheath adapted to administer treatment to the patient. Summary of the Invention

[0004] The enhanced dilator includes a dilator shaft defining a lumen for receiving a functional device (e.g., a puncture device) therethrough. The dilator shaft includes a proximal portion for manipulation by a user and a distal portion for placement within or near the heart. A dilator hub is coupled to the proximal portion of the dilator shaft and includes a rotational coupling structure for coupling to a corresponding hub of a treatment sheath.

[0005] Example 1 is a dilator for facilitating access to a patient's heart and for coupling to a sheath including a sheath hub. The dilator includes a dilator shaft defining a lumen adapted to receive and support a puncture device. The dilator shaft includes a proximal portion for manipulation by a user and a distal portion for placement within or near the heart. A dilator hub is coupled to the proximal portion of the dilator shaft. The dilator hub includes a rotational coupling structure for coupling to the sheath hub to prevent relative rotation between the dilator and the sheath. The dilator hub is configured to accommodate an insertion angle.

[0006] Example 2 is the dilator described in Example 1, where the dilator hub is directly connected to the dilator shaft. Example 3 is the dilator according to Example 1 or 2, wherein the sheath is a treatment sheath and the puncture device is an RF puncture device.

[0007] Example 4 is the dilator of any of Examples 1-3, further comprising an axial locking feature configured to provide resistance to an axial disengagement force to axially secure the dilator hub within the sheath hub.

[0008] Example 5 is the dilator of any of Examples 1-4, wherein the axial locking feature includes a protrusion configured to mate with the shoulder. Example 6 is the dilator of Example 5, in which the protrusion is annular.

[0009] Example 7 is the dilator of any of Examples 1-6, wherein the dilator hub includes an angled disengagement surface adapted to contact a mating surface on the sheath hub.

[0010] Example 8 is the dilator of Example 7, wherein when the dilator hub rotates, the mating surface generates an axial disengagement force against the disengagement surface. Example 9 is the dilator of Example 8, where when the disengagement force is increased to release the axial lock, both axial and rotational relative movement occurs.

[0011] Example 10 is the dilator of Example 7, wherein the angled disengaging surface and the angled engaging surface have different angles from each other. Example 11 is the dilator of Example 7, where the angled disengaging and mating surfaces have the same angle.

[0012] Example 12 is the dilator of any of Examples 1 to 11, wherein the rotational coupling structure includes a plurality of tapered surfaces. Example 13 is the dilator of example 12, wherein the sheath hub includes a plurality of surfaces corresponding to the plurality of tapered surfaces.

[0013] Example 14 is the dilator of any one of Examples 1 to 13, wherein the dilator hub is configured to allow an insertion angle. Example 15 is the dilator of any one of Examples 1 to 14, wherein the sheath hub has a tapered or funnel-shaped opening.

[0014] Example 16 is a dilator for facilitating access to a patient's heart and for coupling to a sheath including a sheath hub. The dilator includes a dilator shaft defining a lumen adapted to receive and support a puncture device. The dilator shaft includes a proximal portion for manipulation by a user and a tapered distal portion for placement within or near the heart. The dilator hub is coupled to the proximal portion of the dilator shaft. The dilator hub includes a rotational coupling structure for coupling to the sheath hub to prevent relative rotation between the dilator and the sheath. The dilator hub is configured to self-align to properly engage with the sheath hub.

[0015] Example 17 is the dilator of Example 16, wherein the dilator hub is directly connected to the dilator shaft. Example 18 is the dilator of Example 16, wherein the sheath is a treatment sheath and the puncture device is an RF puncture device.

[0016] Example 19 is the dilator of Example 16, further comprising an axial locking feature configured to provide resistance to an axial disengagement force to axially secure the dilator hub within the sheath hub.

[0017] Example 20 is the dilator of example 16, wherein the axial locking feature includes a protrusion configured to mate with the shoulder. Example 21 is the dilator of Example 20, where the protrusion is annular.

[0018] Example 22 is the dilator of example 16, wherein the dilator hub includes an angled disengagement surface adapted to contact a mating surface on the sheath hub. Example 23 is the dilator of Example 22, wherein when the dilator hub rotates, the mating surface generates an axial disengagement force against the disengagement surface.

[0019] Example 24 is the dilator of Example 23, where when the disengagement force is increased to release the axial lock, both axial and rotational relative movement occurs. Example 25 is the dilator of Example 22, wherein the angled disengaging surface and the angled engaging surface have different angles from each other.

[0020] Example 26 is the dilator of Example 22, wherein the angled disengaging surface and the angled engaging surface have the same angle. Example 27 is the dilator of example 16, wherein the rotational coupling structure includes a plurality of tapered surfaces.

[0021] Example 28 is the dilator of example 27, wherein the sheath hub includes a plurality of surfaces corresponding to the plurality of tapered surfaces. Example 29 is the dilator of Example 16, wherein the sheath hub has a tapered or funnel-shaped opening.

[0022] Example 30 is a system for facilitating access to a patient's heart. The system includes a sheath having a sheath body defining a lumen adapted to receive a dilator. The sheath body includes a proximal portion and a distal portion. A sheath hub is coupled to the proximal portion of the sheath. The dilator includes a dilator shaft defining a lumen adapted to receive and support a puncture device. The dilator shaft includes a proximal portion for manipulation by a user and a tapered distal portion for placement in or near the heart. The dilator hub is coupled to the proximal portion of the dilator shaft. The dilator hub includes a rotational coupling structure for coupling to the sheath hub to prevent relative rotation between the dilator and the sheath. An axial locking feature is configured to generate resistance to an axial disengagement force to axially secure the dilator hub within the sheath hub.

[0023] Example 31 is the system of Example 30, wherein the sheath hub includes an opening having a tapered mating surface, and the dilator hub includes an angled disengagement surface adapted to contact the tapered mating surface.

[0024] Example 32 is the dilator of example 30, wherein the rotational coupling structure includes a plurality of tapered surfaces. Example 33 is the dilator of Example 30, wherein the axial locking feature includes an annular protrusion configured to mate with a shoulder in the sheath hub.

[0025] Example 34 is a dilator hub for use with a dilator. The dilator hub includes a rotational coupling structure for coupling to a sheath hub to prevent relative rotation between the dilator and the sheath. An axial locking feature is configured to provide resistance to an axial disengagement force to axially secure the dilator hub within the sheath hub.

[0026] Example 35 is the dilator hub of Example 34, wherein the rotational coupling structure includes a plurality of tapered surfaces and the axial locking feature includes an annular protrusion configured to mate with a shoulder of the sheath hub.

[0027] While multiple embodiments are disclosed, still other embodiments of the present invention will become apparent to those skilled in the art from the following detailed description, which shows and describes illustrative embodiments of the invention. Accordingly, the drawings and detailed description are to be regarded as illustrative in nature and not restrictive. [Brief explanation of the drawings]

[0028] [Figure 1A] FIG. 1A is a schematic illustration of a medical procedure within a patient's heart utilizing a transseptal access system according to an embodiment of the present invention. [Figure 1B] FIG. 1B is a schematic illustration of a medical procedure within a patient's heart utilizing a transseptal access system according to an embodiment of the present invention. [Figure 1C] FIG. 1C is a schematic illustration of a medical procedure within a patient's heart utilizing a transseptal access system according to an embodiment of the present invention. [Figure 2A] FIG. 2A is a perspective view of a dilator and sheath according to an embodiment of the present invention. [Figure 2B] FIG. 2B is a perspective view of a dilator and sheath according to an embodiment of the present invention. [Figure 3A] FIG. 3A is a perspective view of a dilator inserted into a sheath in accordance with an embodiment of the present invention. [Figure 3B] FIG. 3B is a perspective view of a dilator hub engaging a sheath hub in accordance with an embodiment of the present invention. [Figure 4A] FIG. 4A is a perspective view of a sheath hub according to an embodiment of the present invention. [Figure 4B] FIG. 4B is a plan view of a portion of a dilator hub mating with a sheath hub in accordance with an embodiment of the present invention. [Figure 5A] FIG. 5A is a cross-sectional view of a dilator hub mating with a sheath hub in accordance with an embodiment of the present invention. [Figure 5B] FIG. 5B is a perspective view of a dilator hub in accordance with an embodiment of the present invention. [Figure 6A] FIG. 6A is a cross-sectional view of a dilator hub in accordance with an embodiment of the present invention. [Figure 6B] FIG. 6B is a cross-sectional view of a dilator hub mating with a sheath hub in accordance with an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0029] While the invention is susceptible to various modifications and alternative forms, specific embodiments have been shown by way of example in the drawings and are described in detail below. However, the invention is not limited to the described embodiments. On the contrary, the invention is intended to cover all modifications, equivalents, and alternatives falling within the scope of the invention as defined by the appended claims.

[0030] 1A-1C are schematic illustrations of a medical procedure 10 within a patient's heart 20 utilizing a transseptal access system 50 in accordance with an embodiment of the present disclosure. As is well known, the human heart 20 has four chambers: a right atrium 55, a left atrium 60, a right ventricle 65, and a left ventricle 70. Separating the right atrium 55 and the left atrium 60 is an interatrial septum 75, and separating the right ventricle 65 and the left ventricle 70 is an interventricular septum 80. As is further known, deoxygenated blood from the patient's body is returned to the right atrium 55 via an inferior vena cava (IVC) 85 or a superior vena cava (SVC) 90.

[0031] Various medical procedures have been developed to diagnose or treat physiological disorders occurring within the left atrium 60 and associated structures. Exemplary such procedures include, but are not limited to, the placement of a diagnostic or mapping catheter within the left atrium 60 for use in generating electroanatomical maps or diagnostic images thereof. Other exemplary procedures include endocardial catheter-based ablation (e.g., radiofrequency ablation, pulsed field ablation, cryoablation, laser ablation, radiofrequency ultrasound ablation, etc.) of target sites within the heart chambers or adjacent blood vessels (e.g., pulmonary veins and their ostia) to terminate cardiac arrhythmias such as atrial fibrillation and atrial flutter. Yet other exemplary procedures may include the placement of a left atrial appendage (LAA) closure device. Of course, the foregoing examples of procedures within the left atrium 60 are merely illustrative and in no way limiting with respect to the present disclosure.

[0032] The medical procedure 10 shown in FIGS. 1A-1C is an exemplary embodiment for providing access to the left atrium 60 using a transseptal access system 50 for subsequent placement of the aforementioned diagnostic and / or therapeutic devices within the left atrium 60. As shown in FIGS. 1A-1C, the target tissue site may be defined by tissue on the interatrial septum 75. In the illustrated embodiment, the target site is accessed via the IVC 85, e.g., through the femoral vein, in accordance with conventional catheterization techniques. In other embodiments, access to the target site on the interatrial septum 75 may be achieved using a superior approach in which the transseptal access system 50 is advanced into the right atrium 55 via the SVC 90.

[0033] In the illustrated embodiment, the transseptal access system 50 includes an introducer sheath 100, a dilator 105 having a dilator body 107 and a tapered distal tip portion 108, and a perforation device (e.g., a radio frequency (RF) perforation device) 110 having a distal end portion 112 terminating in a tip electrode 115. As illustrated, in the assembled, use state shown in FIGS. 1A-1C , the RF perforation device 110 may be disposed within the dilator 105, which may itself be disposed within the sheath 100. In one embodiment in which the transseptal access system 50 is positioned within the right atrium 55 via the IVC 105, the user introduces a guidewire (not shown) into the femoral vein, typically the right femoral vein, and advances it toward the heart 20. The sheath 100 is then introduced over the guidewire into the femoral vein and advanced toward the heart 20. In one embodiment, the guidewire and the distal end of the sheath 100 are then positioned within the SVC 90. These steps may be performed with the assistance of an imaging system (e.g., fluoroscopy or ultrasound imaging). Next, the dilator 105 is introduced into the sheath 100 and over the guidewire and advanced through the sheath 100 into the SVC 90. Alternatively, the dilator 105 may be fully inserted into the sheath 100 before entering the body, and both may be advanced simultaneously toward the heart 20. Once the guidewire, sheath 100, and dilator 105 are positioned within the SVC 90, the guidewire is removed from the body, and the sheath 100 and dilator 105 are retracted so that their distal ends are positioned within the right atrium 55. Next, the RF perforation device 110 described above is introduced into the dilator 105 and advanced toward the heart 20. In various embodiments, the guidewire and RF perforation device are the same component, and therefore, no replacement is necessary.

[0034] The user then positions the distal end of the dilator 105 against the atrial septum 75, which may be performed under imaging guidance. The RF perforation device 110 is then positioned so that the electrode 115 is aligned with or slightly protrudes from the distal end of the dilator 105. The dilator 105 and RF perforation device 110 are dragged along the atrial septum 75, for example, and may be positioned against the fossa ovalis of the atrial septum 75 under imaging guidance. Various additional steps may be performed, such as measuring one or more characteristics of the target site, e.g., electrogram or ECG tracing and / or pressure measurement, or delivering a substance to the target site, e.g., contrast agent delivery. Such steps may facilitate locating the tip electrode 115 at the desired target site. Additionally, tactile feedback provided by the medical RF perforation device 110 can be used to facilitate positioning the tip electrode 115 at the desired target site.

[0035] With the tip electrode 115 and dilator 105 positioned at the target site, energy is delivered from an energy source (e.g., an RF generator) through the RF perforation device 110 to the tip electrode 115 and the target site. In some embodiments, the energy is delivered at a voltage of at least about 75 V (peak-to-peak) and a power of at least about 5 W, and functions to vaporize cells proximate the tip electrode 115, thereby forming a void or perforation through the tissue at the target site. The user then applies force to the RF perforation device 110 to advance the tip electrode 115 at least partially through the perforation. In these embodiments, energy delivery is stopped when the tip electrode 115 passes through the target tissue, i.e., reaches the left atrium 60. In some embodiments, the step of delivering energy occurs for a period of about 1 second to about 5 seconds.

[0036] With the tip electrode 115 of the RF perforation device 110 crossing the atrial septum 75, the dilator 105 can be advanced forward, with the tapered distal tip portion 108 operating to gradually enlarge the perforation so that the distal end of the sheath 100 can be advanced into the left atrium 60.

[0037] In some embodiments, the distal end portion 112 of the RF perforation device 110 may be preformed to assume an atraumatic shape, such as a J-shape (as shown in FIGS. 1B-1C), a pigtail shape, or other shape selected to direct the tip electrode 115 away from the endocardial surface of the left atrium 60. Examples of such RF perforation devices can be found, for example, in U.S. Patent Application Nos. 16 / 445,790 and 16 / 346,404, both of which are assigned to Baylis Medical Company, Inc. Such preformed shapes may advantageously function to minimize the risk of unintended contact between the tip electrode 115 and tissue within the left atrium 60 and may also operate to anchor the distal end portion 112 within the left atrium 60 during subsequent procedural steps. For example, in embodiments, the RF perforation device 110 may be structurally configured to function as a delivery rail for placement of a relatively large inner diameter therapeutic delivery sheath and associated dilator(s). In such embodiments, the dilator 105 and sheath 100 are withdrawn after placement of the distal end portion 112 of the RF perforation device 110 in the left atrium 60. The anchoring feature of the preformed distal end portion 112 inhibits unintentional retraction of the distal end portion 112 and corresponding loss of access to the perforation site on the atrial septum 75 during such withdrawal.

[0038] Various medical procedures have been developed to diagnose or treat physiological disorders occurring within the left atrium 60 and associated structures. Exemplary such procedures include, but are not limited to, the placement of a diagnostic or mapping catheter within the left atrium 60 for use in generating electroanatomical maps or diagnostic images thereof. Other exemplary procedures include endocardial catheter-based ablation (e.g., radiofrequency ablation, pulsed field ablation, cryoablation, laser ablation, radiofrequency ultrasound ablation, etc.) of target sites within the heart chambers or adjacent blood vessels (e.g., pulmonary veins and their ostia) to terminate cardiac arrhythmias such as atrial fibrillation and atrial flutter. Yet other exemplary procedures may include the placement of a left atrial appendage (LAA) closure device. Of course, the foregoing examples of procedures within the left atrium 60 are merely illustrative and in no way limiting with respect to the present disclosure.

[0039] In some embodiments, catheters, treatment devices, and sheaths may be deployed through sheath 100 after sheath 100 has been successfully deployed into the desired heart chamber (e.g., the left atrium). In other embodiments, the treatment device (e.g., a mapping catheter, treatment sheath, medical device, etc.) is part of sheath 100, forming the treatment sheath.

[0040] 2A-2B are perspective views of a dilator and sheath according to an embodiment of the present invention. As shown, a dilator 105 is partially inserted into a lumen of a sheath 100. The dilator 105 includes a handle 201, a dilator hub 202, and a dilator shaft 204. The sheath 100 includes a sheath hub 206 and a sheath body 208.

[0041] 3A and 3B are perspective views of a dilator inserted into a sheath so that the dilator hub 202 begins to interact with a sheath hub 206 (FIG. 3A) and partially inserted into a sheath (FIG. 3B), according to an embodiment of the present invention. As shown, the dilator hub 202 is configured to mate with the sheath hub 206. The hubs 202 and 206 are configured to inhibit or prevent relative rotation of the dilator 105 with respect to the sheath 100 when the dilator hub 202 is fully inserted into the sheath hub 206. As shown in FIG. 3A, tapered surfaces on the hubs 202 and 206 are sized and shaped to allow a user to begin inserting the dilator 105 at a specific offset angle from the longitudinal direction. Similarly, a user can insert the dilator at a specific rotational offset angle from the final engagement angle. These features make it easier for the user to insert and engage both mating hubs because the insertion angle does not need to be perfectly aligned. In these embodiments, these tapered surfaces guide the dilator hub 202 into the proper engagement orientation. As shown, these tapered surfaces self-align from offset angles up to 20 degrees. When the dilator hub 202 is placed within the sheath hub 206, relative rotation of the dilator 105 with respect to the sheath 100 is prevented, creating a rotational lock between the two components. This allows the user to simultaneously rotate the dilator 105 and sheath 100 together.

[0042] FIG. 4A is a perspective view of a sheath hub according to an embodiment of the present invention, and FIG. 4B is a plan view of a portion of a dilator hub that mates with the sheath hub. As shown in FIG. 4A, the sheath hub 206 has an opening 210 surrounding a lumen 212 adapted to receive a dilator shaft. In various embodiments, the opening 210 has an axially tapered or funnel shape. The opening 210 includes arcuate angled or tapered surfaces 251 on either side of the lumen 212. The opening 210 also includes tapered surfaces 252 disposed adjacent to the arcuate tapered surfaces 251 at the bottom and top of the opening 210. In one aspect, there are four tapered surfaces 252. As described further below, the tapered surfaces 252 are configured to interact with angled disengagement surfaces 250 of the dilator hub 202. In certain embodiments, the arcuate tapered surface 251 is configured to interact with the angled disengagement surface 250. As shown in FIG. 4B , when the dilator 105 is inserted longitudinally into the sheath, the dilator hub 202 has an outer surface 216 that remains outside the opening 210 in the sheath hub 206, while the tapered surface 252 and the angled disengagement surface 250 contact each other. In this mating configuration, relative rotation between the sheath hub 206 and the dilator hub 202 is prevented. The outer surface 216 includes opposing longitudinal surfaces 230 and 232 that extend along the longitudinal axis of the hub and opposing lateral surfaces 240 and 242 that extend radially outward and generally perpendicular to the longitudinal axis.

[0043] FIG. 5A is a cross-sectional view of a dilator hub 202 mating with a sheath hub 206, and FIG. 5B is a perspective view of the dilator hub 202, according to an embodiment of the present invention. As shown in FIG. 5A, the dilator is fully inserted into the sheath such that the dilator hub 202 is fully engaged with the sheath hub 206. As shown, the distal end of the dilator hub 202 includes an axial locking feature 220 including protrusions 224. In some aspects, the protrusions 224 are annular protrusions located on the outer periphery of the dilator hub 202. As shown in FIG. 5A, these protrusions 224 are configured to engage with corresponding shoulders 236 on the sheath hub 206. The interaction between the protrusions 224 and the shoulders 236 provides resistance to the axial disengagement force, axially securing the dilator hub 202 within the sheath hub 206. In certain aspects, the shoulders 236 can take the form of elastically deformable O-rings. When the dilator hub 202 is inserted into the sheath hub 206, the protrusion 224 deforms the O-ring and enters the locking chamber 237. To axially lock the dilator hub 202 to the sheath hub 206, the protrusion 224 remains within the locking chamber 237 and cannot move proximally past the shoulder 236. In certain aspects, the locking chamber 237 is configured to allow slight axial movement of the protrusion 224 by providing space between the shoulder 236 and the protrusion 224. In other aspects, the locking chamber 237 is configured to securely retain the protrusion 224, with the protrusion contacting the shoulder 236. The dilator hub 202 and the sheath hub 206 are configured such that when the protrusion is positioned within the locking chamber 237, the tapered surface 252 and the angled disengagement surface 250 approach or contact each other, inhibiting or preventing relative rotation as described above.

[0044] FIG. 6A is a cross-sectional view of a dilator hub according to an embodiment of the present invention, and FIG. 6B is a cross-sectional view of the dilator hub mating with a sheath hub. As shown, the dilator hub 202 includes an angled disengagement surface 250. The disengagement surface 250 mates with a corresponding tapered surface 252 on the sheath hub 206. These two surfaces may have slightly different angles or the same angle (but not be horizontally oriented) so that when torque is applied to the dilator hub 202, the tapered surface 252 exerts an axial disengagement force against the disengagement surface 250. In certain aspects, the angled disengagement surface 250 and the tapered surface 252 may have an angle ranging from 5 degrees to 25 degrees relative to the longitudinal axis. In certain aspects, the angle may be approximately 10 degrees. The disengagement force (which has an axial force component) causes the dilator hub 202 to move axially, thereby disengaging the dilator hub 202 from the sheath hub 206. When the disengagement force overcomes the axial locking force created by the interaction between the annular projections 224 and the shoulders 236, both axial and rotational relative motion occurs. By varying the angle of these surfaces, the amount of torque and degree of rotation required for disengagement can be adjusted.

[0045] In certain embodiments, the disengagement surface 250 mates with a corresponding arcuate tapered surface 251 on the sheath hub 206. These two surfaces may have slightly different angles or the same angle (but not be horizontally oriented) such that when torque is applied to the dilator hub 202, the tapered surface 251 exerts an axial disengagement force on the disengagement surface 250. In certain aspects, the angled disengagement surface 250 and the tapered surface 251 may be at an angle ranging from 5 to 25 degrees relative to the longitudinal axis. In certain aspects, the angle may be approximately 10 degrees. The disengagement force causes the dilator hub 202 to move axially, thereby disengaging the dilator hub 202 from the sheath hub 206. When the disengagement force overcomes the axial locking force created by the interaction between the annular projections 224 and the shoulders 236, both axial and rotational relative movement occurs. By varying the angles of these surfaces, the amount of torque and degree of rotation required for disengagement can be adjusted. In some embodiments, both surfaces 251 and 252 are configured to interact with surface 250 to create a disengagement force.

[0046] Various modifications and additions can be made to the exemplary embodiments described without departing from the scope of the present invention. For example, while the above-described embodiments refer to particular features, the scope of the present invention also includes embodiments having different combinations of features and embodiments that do not include all of the described features. Accordingly, the scope of the present invention is intended to embrace all such alternatives, modifications, and variations that fall within the scope of the claims, together with all equivalents thereof.

Claims

1. 1. A dilator for facilitating access to a patient's heart and for connecting to a sheath including a sheath hub, comprising: a dilator shaft defining a lumen adapted to receive and support a puncture device, the dilator shaft including a proximal portion for manipulation by a user and a distal portion for placement in or near the heart; A dilator comprising: a dilator hub connected to the proximal portion of the dilator shaft, the dilator hub including a rotational coupling structure for coupling to the sheath hub to prevent relative rotation between the dilator and the sheath.

2. The dilator of claim 1 , wherein the dilator hub is directly coupled to the dilator shaft.

3. The dilator according to claim 1 or 2, wherein the sheath is a treatment sheath and the puncture device is an RF puncture device.

4. The dilator of any one of claims 1 to 3, further comprising an axial locking feature configured to provide resistance to an axial disengagement force to axially secure the dilator hub within the sheath hub.

5. The dilator of any one of claims 1 to 4, wherein the axial locking feature comprises a protrusion configured to mate with a shoulder.

6. The dilator according to claim 5 , wherein the protrusion is annular.

7. The dilator of any one of claims 1 to 6, wherein the dilator hub includes an angled disengagement surface adapted to contact a mating surface on the sheath hub.

8. The dilator of claim 7 , wherein the mating surface generates an axial disengagement force against the disengagement surface when the dilator hub is rotated.

9. The dilator of claim 8 , wherein when the disengagement force is increased to release the axial lock, both axial and rotational relative movement occurs.

10. The dilator of claim 7 , wherein the angled disengagement surface and the mating surface have different angles from each other.

11. The dilator of claim 7 , wherein the angled disengagement surface and the mating surface have the same angle.

12. The dilator according to any one of claims 1 to 11, wherein the rotational coupling structure includes a plurality of tapered surfaces.

13. The dilator of claim 12 , wherein the sheath hub includes a plurality of surfaces corresponding to the plurality of tapered surfaces.

14. The dilator according to any one of claims 1 to 13, wherein the dilator hub is configured to allow for angled insertion.

15. The dilator according to any one of claims 1 to 14, wherein the sheath hub has a tapered or funnel-shaped opening.

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