Guide catheter for an implant delivery apparatus

Abstract

Devices and methods for providing a hemostatic valve fluid seal within a guide catheter or delivery apparatus are disclosed. An example delivery apparatus includes a seal housing assembly that includes a seal housing and a seal stack disposed within the seal housing. The seal stack includes a fluid seal having a first surface, having a circular shape, and a second surface, having a circular shape, disposed opposite to the first surface. The fluid seal defines a slit extending from the first surface to the second surface through centers of the first and second surfaces.

Description

[0001]Attorney Docket No: THVMC-23646WO01 GUIDE CATHETER FOR AN IMPLANT DELIVERY APPARATUS CROSS-REFERENCE TO RELATED APPLICATION This application claims the benefit of U.S. Provisional Application No.63 / 634,289, filed April 15, 2024, which is incorporated by reference in its entirety for all purposes. FIELD The present disclosure relates to guide catheters for delivery apparatuses for prosthetic medical devices. BACKGROUND The human heart may suffer from various valvular diseases. These valvular diseases may result in significant malfunctioning of the heart and ultimately require repair of the native valve or replacement of the native valve with an artificial valve. There are a number of known repair devices (e.g., stents) and artificial valves, as well as a number of known methods of implanting these devices and valves in humans. Percutaneous and minimally invasive surgical approaches are used in various procedures to deliver prosthetic medical devices to locations inside the body that are not readily accessible by surgery or where access without surgery is desirable. Some of the devices used in these procedures include guidewires, catheters, guide sheaths, and the like, which aid in the insertion of a prosthetic heart valve inside the body. In one specific example, a prosthetic heart valve may be mounted in a crimped state on the distal end of a delivery apparatus and advanced through the patient’s vasculature (e.g., through a femoral artery or femoral vein) until the prosthetic valve reaches the implantation site in the heart. The prosthetic valve is then expanded to its functional size, for example, by inflating a balloon on which the prosthetic valve is mounted, actuating a mechanical actuator that applies an expansion force to the prosthetic valve, or by deploying the prosthetic valve from a sheath of the delivery apparatus so that the prosthetic valve may self-expand to its functional size. A guide catheter (which may also be referred to as a guide sheath) may be used for introducing a delivery apparatus, such as the prosthetic heart valve delivery apparatus described above, into the patient’s vasculature. The guide catheter may include an elongated shaft that is inserted into the vasculature and a handle that remains outside the patient and may be used to manipulate the shaft. The delivery apparatus may be pushed Attorney Docket No: THVMC-23646WO01 through a main lumen of the guide catheter to help navigate the delivery apparatus to a target implantation site within the patient. However, a disadvantage of many guide catheters (guide sheaths) is that they may not be able to aspirate the guide sheath without allowing fluid, e.g., air, across the seal of the guide sheath and into the human body, due to the differences in pressure gradients between the inside and outside of the guide catheter or sheath from different anatomical pressure conditions in different parts of the human body, when executing an aspirate and flush step. This type of intravascular guide sheath can also create a vacuum effect during valve delivery which may undesirably introduce air into the system through the seal, and thus, may be less effective in preventing air emboli in the venous side. As such, there is a need for a hemostatic valve seal assembly with a hemostatic valve fluid seal that better prevents air from traveling across the hemostatic valve seal of the guide sheath. SUMMARY Described herein are delivery apparatuses and methods including a guide catheter and a hemostatic valve fluid (e.g., air) seal (hereinafter referred to as the “fluid seal”) within the guide catheter (i.e., guide sheath), for limiting the entry of fluid (e.g., air) during the implanting of prosthetic heart valves. The disclosed guide catheters can, for example, be configured to receive a portion of a delivery apparatus within a main lumen of the guide catheter to introduce the delivery apparatus into a patient’s vasculature. In some examples, the guide catheter may include a reservoir of fluid that is fluidly coupled with the main lumen within a handle of the guide catheter that provides a location for fluid (e.g., air) to accumulate for removal as a delivery apparatus is being navigated through the main lumen. As such, the devices and methods disclosed herein can, among other things, overcome one or more of the deficiencies of typical guide catheters. In one representative example, a delivery apparatus comprises a seal housing assembly comprising a seal housing and a seal stack disposed within the seal housing. The seal stack comprises a fluid seal having a first surface, having a circular shape, and a second surface, having a circular shape, disposed opposite to the first surface. The fluid seal defines a slit extending from the first surface to the second surface through centers of the first and second surfaces. In another representative example, a delivery apparatus comprises a handle and a shaft. The handle comprises a proximal segment, an intermediate segment, and a distal Attorney Docket No: THVMC-23646WO01 segment. The proximal segment comprises a seal housing assembly comprising a seal housing and a seal stack disposed within the seal housing. The seal stack is configured to allow insertion of a device into the handle and prevent fluid flow past the seal stack. The intermediate segment is disposed adjacent and distal to the proximal segment. The intermediate segment includes an inner surface defining a first lumen. The distal segment is disposed adjacent and distal to the intermediate segment. The shaft extends distally from the handle and includes a distal end, a proximal end, and a second lumen extending between the distal end and the proximal end of the shaft. The proximal end of the shaft is disposed within the distal segment of the handle and is coupled to the first lumen. The seal stack comprises a fluid seal having a distal surface, having a circular shape, and a proximal surface, having a circular shape, disposed opposite to the distal surface. The fluid seal defines a slit extending from the distal surface to the proximal surface through centers of the distal and proximal surfaces. In another representative example, a method for implanting a prosthetic medical device comprises inserting a shaft of a guide catheter into a vessel of a patient. The method includes inserting a distal end portion of a first implant catheter into a proximal end of a handle of the guide catheter and pushing the distal end portion of the first implant catheter through a seal stack of the handle and then through a main lumen of the shaft of the guide catheter toward a target implantation site for a prosthetic medical device mounted on the distal end portion of the first implant catheter. The seal stack is configured to allow insertion of a device into the handle and prevent fluid flow past the seal stack. The seal stack comprises a fluid seal having a first surface, having a circular shape, and a second surface, having a circular shape, disposed opposite to the first surface. The fluid seal defines a slit extending from the first surface to the second surface through centers of the first and second surfaces. In another representative example, a seal housing assembly for a delivery apparatus comprises a housing, a fluid seal, a space, and a cross-slit valve. The fluid seal is disposed within the housing. The spacer is disposed within the housing proximally to the fluid seal. The cross-slit valve is disposed within the housing proximally to the fluid seal. The fluid seal has a distal surface, having a circular shape, and a proximal surface, having a circular shape, disposed opposite to the distal surface. The fluid seal defines a slit extending from the first surface to the second surface through centers of the first and second surfaces. Attorney Docket No: THVMC-23646WO01 The various innovations of this disclosure may be used in combination or separately. This summary is provided to introduce a selection of concepts in a simplified form that are further described below in the detailed description. This summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter. The foregoing and other objects, features, and advantages of the disclosure will become more apparent from the following detailed description, claims, and accompanying figures. BRIEF DESCRIPTION OF THE DRAWINGS FIG.1 schematically illustrates a first stage in an example mitral valve replacement procedure where a guide catheter and a guidewire are inserted into a blood vessel of a patient and navigated through the blood vessel and into a heart of the patient, towards a native mitral valve of the heart. FIG. 2A schematically illustrates a second stage in the example mitral valve replacement procedure where a docking device delivery apparatus extending through the guide catheter is implanting a docking device for a prosthetic heart valve at the native mitral valve. FIG. 2B schematically illustrates a third stage in the example mitral valve replacement procedure where the docking device of FIG. 2A is fully implanted at the native mitral valve of the patient and the docking device delivery apparatus has been removed from the patient. FIG. 3A schematically illustrates a fourth stage in the example mitral valve replacement procedure where a prosthetic heart valve delivery apparatus extending through the guide catheter is implanting a prosthetic heart valve in the implanted docking device at the native mitral valve. FIG. 3B schematically illustrates a fifth stage in the example mitral valve replacement procedure where the prosthetic heart valve is fully implanted within the docking device at the native mitral valve and the prosthetic heart valve delivery apparatus has been removed from the patient. FIG. 4 schematically illustrates a sixth stage in the example mitral valve replacement procedure where the guide catheter and the guidewire have been removed from the patient. Attorney Docket No: THVMC-23646WO01 FIG.5 is a side view of a guide catheter configured to receive a delivery apparatus and guide the delivery apparatus through a portion of a patient’s vasculature, according to one example. FIG.6 is a cross-sectional side view of a portion of the guide catheter of FIG.5. FIG.7 is a side view of a delivery apparatus for a docking device, according to one example. FIG.8 is a perspective view of a docking device for use with the delivery apparatus of FIG.7, according to one example. FIG. 9 is a perspective view of a delivery apparatus for a prosthetic heart valve, according to one example. FIG.10 is a perspective view of a prosthetic heart valve for use with the delivery apparatus of FIG.9, according to one example. FIG.11 is a perspective view of a reservoir for a guide catheter, according to one example. FIG. 12A is an exploded perspective view of a seal stack for a guide catheter, according to one example. FIG. 12B is a perspective view of an assembled seal stack for a guide catheter, according to one example. FIGS. 13A, 13B, and 13C respectively include a perspective view, a distal view, and a cross-sectional side view of a fluid seal for a guide catheter, according to one example. DETAILED DESCRIPTION General Considerations For purposes of this description, certain aspects, advantages, and novel features of examples of this disclosure are described herein. The disclosed methods, apparatus, and systems should not be construed as being limiting in any way. Instead, the present disclosure is directed toward all novel and nonobvious features and aspects of the various disclosed examples, alone and in various combinations and sub-combinations with one another. The methods, apparatus, and systems are not limited to any specific aspect or feature or combination thereof, nor do the disclosed examples require that any one or more specific advantages be present or problems be solved. Attorney Docket No: THVMC-23646WO01 Although the operations of some of the disclosed examples are described in a particular, sequential order for convenient presentation, it should be understood that this manner of description encompasses rearrangement, unless a particular ordering is required by specific language set forth below. For example, operations described sequentially may in some cases be rearranged or performed concurrently. Moreover, for the sake of simplicity, the attached figures may not show the various ways in which the disclosed methods may be used in conjunction with other methods. Additionally, the description sometimes uses terms like “provide” or “achieve” to describe the disclosed methods. These terms are high-level abstractions of the actual operations that are performed. The actual operations that correspond to these terms may vary depending on the particular implementation and are readily discernible by one of ordinary skill in the art. As used in this application and in the claims, the singular forms “a,” “an,” and “the” include the plural forms unless the context clearly dictates otherwise. Additionally, the term “includes” means “comprises.” Further, the term “coupled” generally means physically, mechanically, chemically, magnetically, and / or electrically coupled or linked and does not exclude the presence of intermediate elements between the coupled or associated items absent specific contrary language. As used herein, the term “proximal” refers to a position, direction, or portion of a device that is closer to the user and further away from the implantation site. As used herein, the term “distal” refers to a position, direction, or portion of a device that is further away from the user and closer to the implantation site. Thus, for example, proximal motion of a device is motion of the device away from the implantation site and toward the user (e.g., out of the patient’s body), while distal motion of the device is motion of the device away from the user and toward the implantation site (e.g., into the patient’s body). The terms “longitudinal” and “axial” refer to an axis extending in the proximal and distal directions, unless otherwise expressly defined. Introduction to the Disclosed Technology This disclosure is related to seal stacks that are intended to help address the problem of hemostasis in transcatheter access sheaths. For technologies in the transcatheter space that are minimally invasive, access sheaths may help to deliver a variety of catheter types to perform an array of different procedures and functions. Access sheaths require hemostatic seals to prevent loss of blood from the patient for the duration of the procedure Attorney Docket No: THVMC-23646WO01 while also preventing anything from the outside environment from getting into the patient, such as air emboli. This disclosure relates to a seal stack for use in a guide sheath or guide catheter for use in delivery apparatuses for prosthetic devices, such as in delivery apparatuses, described here. For example, the seal stack may be seal stack 124 in guide catheter or guide sheath 100 depicted in FIG.6. Described herein are various systems, apparatuses, methods, or the like, that, in some examples, may be used in or with delivery apparatuses for prosthetic medical devices (such as prosthetic heart valves or docking devices). In some examples, such systems, apparatuses, and / or methods include a hemostatic valve fluid seal disposed within the delivery apparatus that prevents fluid (e.g., air) from entering into the human body upon insertion into the human body of the delivery apparatus. In some examples, the delivery apparatus may include a hemostatic valve fluid seal disposed within the delivery apparatus that prevents fluid (e.g., air) from entering into the human body upon insertion into the human body of the delivery apparatus, via a circular polyisoprene material or elastomeric silicone with a slit (or coin-slit) configuration. The hemostatic valve fluid seal thus reduces the risk of air entering into the patient’s vasculature. Generally, the seal stack comprises a fluid seal with a slit configuration. The fluid seal may have a disc or cylindrical shape. See, for example, FIGS.12A and 13A. In some embodiments, the fluid seal may have a thickness of about 1 / 16-1 / 4 inches, or about 0.05- 0.2 inches, such as about 1 / 8 inch or about 0.125 inches, and a diameter of about 0.5-1 inches, such as about 0.75 inches. The disc shaped fluid seal may have a single slit that passes completely through the fluid seal. FIGS.12A-13C depict some examples of such a disc shaped seal with a single slit (i.e., a coin-slit configuration). In some embodiments, the slit may have a length (e.g., in a proximal surface and in a distal surface of the fluid seal) of about 1 / 16-1 / 3 inches, or about 0.1-0.3 inches, such as about 0.217 inches. The slit penetrates completely through the disc from a first circular face or surface of the disc to a second circular face or surface that is opposite the first. The slit may be arranged approximately in the center of the disc, e.g., such that the slit passes through or approximately through a center of one or both of the first and second circular faces or surfaces. The slit may enable catheter entry and removal without creating an opening clear of material during entry or removal or while the catheter is positioned therethrough. Attorney Docket No: THVMC-23646WO01 The fluid seal may be composed of any suitable material, such as a polyisoprene material, e.g., polyisoprene rubber, or an elastomeric silicone, e.g., liquid silicone rubber (LSR) or high consistency rubber (HCR). In some embodiments, the material of the fluid seal has a Shore hardness of about 25-50 A, e.g., about 25-45 A, about 30-40 A, about 25- 30 A, about 30-35 A, about 35-40 A, about 40-42 A, about 42-44 A, about 44-46 A, about 46-48 A, or about 48-50 A. In some embodiments, the material of the fluid seal may have 500-1500% elongation, such as about 500-800% elongation, about 800-1100% elongation, or about 1100-1500% elongation. One example of a suitable polyisoprene rubber is characterized by a 30 A hardness with suitable material elongation properties. This material may be versatile for the application of hemostatic seals on an access sheath device that may need to allow various catheter diameter sizes to go through the seal. In one example, the fluid seal comprises an enhanced tear resistant (ETR) silicone elastomer. In another example, the fluid seal may comprise an LSR. In another example, the fluid seal may specifically comprise LSR 4325. In another example, the fluid seal may comprise an HCR. In another example, the fluid seal may have a clear appearance. A fluid seal may be incorporated into a seal stack as shown in FIGS.12A-B. Such a fluid seal is incorporated, for example into seal stack 124 in guide catheter or guide sheath 100 depicted in FIGS.5 and 6. In some embodiments, the fluid seal may be part of a seal stack comprising the fluid seal and a spacer and / or a cross-slit valve. For example, FIG.12A illustrates a seal stack 600 that includes fluid seal 602, spacer 603, and cross-slit valve 604. Referring to FIGS. 12A-B, in some embodiments, the spacer 603 may be a rigid plastic component comprising black ABS material. The spacer 603 may be an injection- molded component used to provide structural support and fitment for other components (e.g., fluid seal 602, cross-slit valve 604) retained inside the guide sheath seal housing assembly and serve as a compression force for retention of the seal stack 600. The spacer 603 may fit the cross-slit valve 604 and provide peripheral structural integrity for the seal stack components that reside inside a seal stack housing 609, which may be comprised of polycarbonate. The spacer 603 is typically a rigid circular component with a hollow central diameter. In some embodiments, the spacer 603 may have an outer diameter that is the same as, or similar to, that of the fluid seal 602, e.g., a diameter of about 0.5-1 inches, such as about 0.75 inches. In some embodiments, the spacer 603 may have an inner diameter that Attorney Docket No: THVMC-23646WO01 is about 50-95%, about 70-90%, or about 80%, of the outer diameter of the spacer 603, such as about 0.4-0.9 inches or about 0.6 inches. The inner diameter of the spacer 603 may be sized to the exterior of a minor outer diameter portion 607 of the cross-slit valve 604 so that the exterior of the minor outer diameter portion 607 of the cross-slit valve 604 fits snugly against the inner diameter of the spacer 603. The minor outer diameter portion 607 of the cross-slit valve 604 may be shaped to fit snugly into the interior of the spacer 603 so that the minor outer diameter portion 607 of the cross-slit valve 604 fits snugly against the proximal surface of the fluid seal 602. For example, the minor outer diameter portion 607 of the cross-slit valve 604 may have an outer diameter of about 0.4-0.9 inches or about 0.6 inches, and a thickness of about 0.2-0.4 inches, or about 0.3 inches. The spacer 603 may have a thickness that accommodates the minor outer diameter portion 607 of the cross-slit valve 604, so that the distal surface of the cross-slit valve 604 fits snugly against the proximal surface of the fluid seal 602. In some embodiments, the spacer 603 has a thickness of about 0.2-0.4 inches, or about 0.3 inches. In some embodiments, the cross-slit valve 604 is included, and helps to hold fluid seal 602 in place. In some embodiments, the cross-slit valve 604 is composed of polyisoprene material. Thus, in summary and as depicted in FIG 13B, the fluid seal assembly 608 comprises the cross-slit valve 604, and particularly the minor outer diameter portion 607 of cross-slit valve 604, fitting snugly inside the inner diameter of spacer 603, and the fluid seal 602 fitting snugly against a distal surface of the minor outer diameter portion 607 of the cross-slit valve 604. In certain embodiments, the cross-slit valve 604 may be comprised of polyisoprene, platinum-cured silicone material, or other suitable material, and may be compliant and possess built-in retention features. The proximal side of the cross-slit valve 604 may possess a conical shape which enables catheters entering a human body to converge towards the center of the entry point. Functionally, fluid seal 602, which defines a slit directly within its center in certain embodiments, allows entering catheter systems to converge and be inserted into the center of the access sheath and thereby into the human body. During use of the guide sheath or catheter in a medical procedure, the cross-slit valve 604 also helps maintain entering catheter systems generally centered throughout the entirety of the procedure. There is also a central exposed pinhole in the design embedded within central cross slits of cross-slit valve 604. This pinhole may provide hemostasis when a guidewire is across, as the central pinhole diameter may match the outer diameter of the conventionally used guidewires in typical transcatheter procedures. Attorney Docket No: THVMC-23646WO01 In some examples, such systems, apparatuses, and / or methods may provide a reservoir of fluid within a handle of a delivery apparatus that provides a location for fluid (e.g., air) to accumulate for removal as a prosthetic medical device mounted on another delivery apparatus is navigated through the reservoir and a lumen of the delivery apparatus toward an implantation site in a body of a patient. For example, the delivery apparatus may be inserted into a vessel of a patient and another delivery apparatus including a prosthetic medical device (e.g., a prosthetic heart valve) mounted thereon may be navigated through a main lumen of the delivery apparatus toward a target implantation site for the prosthetic medical device. In some examples, the delivery apparatus may include a reservoir within a handle of the delivery apparatus that has a larger inner diameter than an inner diameter of the main lumen. As such, the reservoir may provide a location (e.g., at the larger inner diameter) for air to accumulate and / or become trapped while another delivery apparatus is navigated through the delivery apparatus. The trapped air may be removed from the system, thereby preventing or reducing the risk of air entering the patient’s vasculature. In some examples, the delivery apparatuses disclosed herein may be used to introduce one or more delivery apparatuses (or implant catheters) into the vasculature of a patient and guide the one or more delivery apparatuses at least partially through the vasculature toward a target implantation site. For example, FIGS. 1-4 schematically illustrate an example transcatheter heart valve replacement procedure which utilizes a guide catheter to guide a docking device delivery apparatus toward a native valve annulus and then a prosthetic heart valve delivery apparatus toward the native valve annulus. The docking device delivery apparatus is used to deliver a docking device to the native valve annulus and then the prosthetic heart valve delivery apparatus is used to deliver a transcatheter prosthetic heart valve inside the docking device. As introduced above, defective native heart valves may be replaced with transcatheter prosthetic heart valves. However, such prosthetic heart valves may not be able to sufficiently conform to the geometry of the native tissue (e.g., to the leaflets and / or annulus of the native heart valve) and may undesirably shift around relative to the native tissue, which may lead to paravalvular leakage. Thus, a docking device may be implanted first at the native valve annulus and then the prosthetic heart valve may be implanted within the docking device to help anchor the prosthetic heart valve to the native tissue and provide a seal between the native tissue and the prosthetic heart valve. An example delivery apparatus for delivering a docking device at a native heart valve is shown in FIG. 7, and Attorney Docket No: THVMC-23646WO01 an example docking device is shown in FIG. 8. An example delivery apparatus for delivering a prosthetic heart valve within a docking device at a native heart valve is shown in FIG.9, and an example prosthetic heart valve is shown in FIG.10. Example guide catheters are shown in more detail in FIGS.5-6. In some examples, as shown in FIG.6, a guide catheter may include a reservoir within a handle of the guide catheter that is filled with fluid and fluidly coupled to the main lumen of the guide catheter. Additional details of an example reservoir are shown in FIG. 11. The reservoir may provide a location for air to collect and / or become trapped within the reservoir (e.g., a location having a larger inner diameter than the main lumen of the guide catheter, etc.), where such air may have been introduced into the system as a delivery apparatus is introduced through the guide catheter. Subsequently, in some instances, the trapped air may be removed from the reservoir (e.g., via a port). As a result, the reservoir prevents or reduces the likelihood of air from moving distally through the system. The hemostatic valve fluid seal thus reduces the risk of air entering into the patient’s vasculature. Examples of the Disclosed Technology FIGS.1-4 depict an example transcatheter heart valve replacement procedure (e.g., a mitral valve replacement procedure) which utilizes a docking device 52 and a prosthetic heart valve 62, according to one example. During the procedure, a user first creates a pathway to a patient’s native heart valve using a guide catheter 30 (FIG.1). The user then delivers and implants the docking device 52 at the patient’s native heart valve using a docking device delivery apparatus 50 (FIG. 2A) and then removes the docking device delivery apparatus 50 from the patient 10 after implanting the docking device 52 (FIG. 2B). The user then implants the prosthetic heart valve 62 within the implanted docking device 52 using a prosthetic valve delivery apparatus 60 (FIG. 3A). Thereafter, the user removes the prosthetic valve delivery apparatus 60 from the patient 10 (FIG.3B), as well as the guide catheter 30 (FIG.4). FIG. 1 depicts a first stage in a mitral valve replacement procedure, according to one example, where the guide catheter 30 and a guidewire 40 are inserted into a blood vessel 12 of a patient 10 and navigated through the blood vessel 12, into a heart 14 of the patient 10, and toward the native mitral valve 16. Together, the guide catheter 30 and the guidewire 40 may provide a path for the docking device delivery apparatus 50 and the prosthetic valve delivery apparatus 60 to be navigated through and along, to the implantation site (the native mitral valve 16 or native mitral valve annulus). Attorney Docket No: THVMC-23646WO01 Initially, the user may first make an incision in the patient’s body to access the blood vessel 12. For example, in the example illustrated in FIG. 1, the user may make an incision in the patient’s groin to access a femoral vein. Thus, in such examples, the blood vessel 12 may be a femoral vein. After making the incision at the blood vessel 12, the user may insert the guide catheter 30, the guidewire 40, and / or additional devices (such as an introducer device or transseptal puncture device) through the incision and into the blood vessel 12. The guide catheter 30 (which may also be referred to as an “introducer device,” “introducer,” or “guide sheath”) is configured to facilitate the percutaneous introduction of various implant delivery devices (e.g., the docking device delivery apparatus 50 and the prosthetic valve delivery apparatus 60) into and through the blood vessel 12 and may extend through the blood vessel 12 and into the heart 14 but may stop short of the native mitral valve 16. The guide catheter 30 may comprise a handle 32 and a shaft 34 extending distally from the handle 32. The shaft 34 may extend through the blood vessel 12 and into the heart 14 while the handle 32 remains outside the body of the patient 10 and may be operated by the user to manipulate the shaft 34 (FIG.1). The guidewire 40 is configured to guide the delivery apparatuses (e.g., the guide catheter 30, the docking device delivery apparatus 50, the prosthetic valve delivery apparatus 60, additional catheters, or the like) and their associated devices (e.g., docking device, prosthetic heart valve, and the like) to the implantation site within the heart 14, and thus may extend all the way through the blood vessel 12 and into a left atrium 18 of the heart 14 (and in some examples, through the native mitral valve 16 and into a left ventricle of the heart 14) (FIG.1). In some instances, a transseptal puncture device or catheter may be used to initially access the left atrium 18, prior to inserting the guidewire 40 and the guide catheter 30. For example, after making the incision to the blood vessel 12, the user may insert a transseptal puncture device through the incision and into the blood vessel 12. The user may guide the transseptal puncture device through the blood vessel 12 and into the heart 14 (e.g., through the femoral vein and into the right atrium 20). The user may then make a small incision in an atrial septum 22 of the heart 14 to allow access to the left atrium 18 from the right atrium 20. The user may then insert and advance the guidewire 40 through the transseptal puncture device within the blood vessel 12 and through the incision in the atrial septum 22 into the left atrium 18. Once the guidewire 40 is positioned within the left atrium 18 and / or Attorney Docket No: THVMC-23646WO01 the left ventricle 26, the transseptal puncture device may be removed from the patient 10. The user may then insert the guide catheter 30 into the blood vessel 12 and advance the guide catheter 30 into the left atrium 18 over the guidewire 40 (FIG.1). In some instances, an introducer device may be inserted through a lumen of the guide catheter 30 prior to inserting the guide catheter 30 into the blood vessel 12. In some instances, the introducer device may include a tapered end that extends out a distal tip of the guide catheter 30 and that is configured to guide the guide catheter 30 into the left atrium 18 over the guidewire 40. Additionally, in some instances the introducer device may include a proximal end portion that extends out a proximal end of the guide catheter 30. Once the guide catheter 30 reaches the left atrium 18, the user may remove the introducer device from inside the guide catheter 30 and the patient 10. Thus, only the guide catheter 30 and the guidewire 40 remain inside the patient 10. The guide catheter 30 is then in position to receive an implant delivery apparatus and help guide it to the left atrium 18, as described further below. FIG.2A depicts a second stage in the example mitral valve replacement procedure where a docking device 52 is being implanted at the native mitral valve 16 of the heart 14 of the patient 10 using a docking device delivery apparatus 50 (which may also be referred to as an “implant catheter” and / or a “docking device delivery device”). In general, the docking device delivery apparatus 50 comprises a delivery shaft 54, a handle 56, and a pusher assembly 58. The delivery shaft 54 is configured to be advanced through the patient’s vasculature (blood vessel 12) and to the implantation site (e.g., native mitral valve 16) by the user and may be configured to retain the docking device 52 in a distal end portion 53 of the delivery shaft 54. In some examples, the distal end portion 53 of the delivery shaft 54 retains the docking device 52 therein in a straightened delivery configuration. The handle 56 of the docking device delivery apparatus 50 is configured to be gripped and / or otherwise held by the user, outside the body of the patient 10, to advance the delivery shaft 54 through the patient’s vasculature (e.g., blood vessel 12). In some examples, the handle 56 may comprise one or more articulation members 57 (or rotatable knobs) that are configured to aid in navigating the delivery shaft 54 through the blood vessel 12. For example, the one or more articulation members 57 may comprise one or more of knobs, buttons, wheels, and / or other types of physically adjustable control members that are configured to be adjusted by the user to flex, bend, twist, turn, and / or Attorney Docket No: THVMC-23646WO01 otherwise articulate a distal end portion 53 of the delivery shaft 54 to aid in navigating the delivery shaft 54 through the blood vessel 12 and within the heart 14. The pusher assembly 58 may be configured to deploy and / or implant the docking device 52 at the implantation site (e.g., the native mitral valve 16). For example, the pusher assembly 58 is configured to be adjusted by the user to push the docking device 52 out of the distal end portion 53 of the delivery shaft 54. A shaft of the pusher assembly 58 may extend through the delivery shaft 54 and may be disposed adjacent to the docking device 52 within the delivery shaft 54. In some examples, the docking device 52 may be releasably coupled to the shaft of the pusher assembly 58 via a connection mechanism of the docking device delivery apparatus 50 such that the docking device 52 may be released after being deployed at the native mitral valve 16. Further details of example embodiments of the docking device delivery apparatus and its variants are described in International Publication No. WO2020 / 247907, which is incorporated by reference herein in its entirety. Referring again to FIG.2A, after the guide catheter 30 is positioned within the left atrium 18, the user may insert the docking device delivery apparatus 50 (e.g., the delivery shaft 54) into the patient 10 by advancing the delivery shaft 54 of the docking device delivery apparatus 50 through the guide catheter 30 and over the guidewire 40. In some examples, the guidewire 40 may be at least partially retracted away from the left atrium 18 and into the guide catheter 30. The user may then continue to advance the delivery shaft 54 of the docking device delivery apparatus 50 through the blood vessel 12 along the guidewire 40 until the delivery shaft 54 reaches the left atrium 18, as illustrated in FIG. 2A. Specifically, the user may advance the delivery shaft 54 of the docking device delivery apparatus 50 by gripping and exerting a force on (e.g., pushing) the handle 56 of the docking device delivery apparatus 50 toward the patient 10. While advancing the delivery shaft 54 through the blood vessel 12 and the heart 14, the user may adjust the one or more articulation members 57 of the handle 56 to navigate the various turns, corners, constrictions, and / or other obstacles in the blood vessel 12 and the heart 14. Once the delivery shaft 54 reaches the left atrium 18 and extends out of a distal end of the guide catheter 30, the user may position the distal end portion 53 of the delivery shaft 54 at and / or near the posteromedial commissure of the native mitral valve 16 using the handle 56 (e.g., the articulation members 57). The user may then push the docking device 52 out of the distal end portion 53 of the delivery shaft 54 with the shaft of the Attorney Docket No: THVMC-23646WO01 pusher assembly 58 to deploy and / or implant the docking device 52 within the annulus of the native mitral valve 16. In some examples, the docking device 52 may be constructed from, formed of, and / or comprise a shape memory material, and as such, may return to its original, pre- formed shape when it exits the delivery shaft 54 and is no longer constrained by the delivery shaft 54. As one example, the docking device 52 may originally be formed as a coil, and thus may wrap around leaflets 24 of the native mitral valve 16 as it exits the delivery shaft 54 and returns to its original coiled configuration. After pushing a ventricular portion of the docking device 52 (e.g., the portion of the docking device 52 shown in FIG. 2A that is configured to be positioned within a left ventricle 26 and / or on the ventricular side of the native mitral valve 16), the user may then deploy the remaining portion of the docking device 52 (e.g., an atrial portion of the docking device 52) from the delivery shaft 54 within the left atrium 18 by retracting the delivery shaft 54 away from the posteromedial commissure of the native mitral valve 16. After deploying and implanting the docking device 52 at the native mitral valve 16, the user may disconnect the docking device delivery apparatus 50 from the docking device 52. Once the docking device 52 is disconnected from the docking device delivery apparatus 50, the user may retract the docking device delivery apparatus 50 out of the blood vessel 12 and away from the patient 10 so that the user may deliver and implant a prosthetic heart valve 62 within the implanted docking device 52 at the native mitral valve 16. FIG. 2B depicts this third stage in the mitral valve replacement procedure, where the docking device 52 has been fully deployed and implanted at the native mitral valve 16 and the docking device delivery apparatus 50 (including the delivery shaft 54) has been removed from the patient 10 such that only the guidewire 40 and the guide catheter 30 remain inside the patient 10. In some examples, after removing the docking device delivery apparatus, the guidewire 40 may be advanced out of the guide catheter 30, through the implanted docking device 52 at the native mitral valve 16, and into the left ventricle 26 (FIG. 2A). As such, the guidewire 40 may help to guide the prosthetic valve delivery apparatus 60 through the annulus of the native mitral valve 16 and at least partially into the left ventricle 26. As illustrated in FIG.2B, the docking device 52 may comprise a plurality of turns (or coils) that wrap around the leaflets 24 of the native mitral valve 16 (within the left Attorney Docket No: THVMC-23646WO01 ventricle 26). The implanted docking device 52 has a more cylindrical shape than the annulus of the native mitral valve 16, thereby providing a geometry that more closely matches the shape or profile of the prosthetic heart valve to be implanted. As a result, the docking device 52 may provide a tighter fit, and thus a better seal, between the prosthetic heart valve and the native mitral valve 16, as described further below. FIG.3A depicts a fourth stage in the mitral valve replacement procedure where the user is delivering and / or implanting a prosthetic heart valve 62 (which may also be referred to herein as a “transcatheter heart valve” or “THV” for short, “replacement heart valve,” and / or “prosthetic mitral valve”) within the docking device 52 using a prosthetic valve delivery apparatus 60. As shown in FIG. 3A, the prosthetic valve delivery apparatus 60 may comprise a delivery shaft 64 and a handle 66, the delivery shaft 64 extending distally from the handle 66. The delivery shaft 64 is configured to extend into the patient’s vasculature to deliver, implant, expand, and / or otherwise deploy the prosthetic heart valve 62 within the docking device 52 at the native mitral valve 16. The handle 66 is configured to be gripped and / or otherwise held by the user to advance the delivery shaft 64 through the patient’s vasculature. In some examples, the handle 66 may comprise one or more articulation members 68 that are configured to aid in navigating the delivery shaft 64 through the blood vessel 12 and the heart 14. Specifically, the articulation member(s) 68 may comprise one or more of knobs, buttons, wheels, and / or other types of physically adjustable control members that are configured to be adjusted by the user to flex, bend, twist, turn, and / or otherwise articulate a distal end portion of the delivery shaft 64 to aid in navigating the delivery shaft 64 through the blood vessel 12 and into the left atrium 18 and left ventricle 26 of the heart 14. In some examples, the prosthetic valve delivery apparatus 60 may include an expansion mechanism 65 that is configured to radially expand and deploy the prosthetic heart valve 62 at the implantation site. In some instances, as shown in FIG. 3A, the expansion mechanism 65 may comprise an inflatable balloon that is configured to be inflated to radially expand the prosthetic heart valve 62 within the docking device 52. The inflatable balloon may be coupled to the distal end portion of the delivery shaft 64. In other examples, the prosthetic heart valve 62 may be self-expanding and may be configured to radially expand on its own upon removal of a sheath or capsule covering the Attorney Docket No: THVMC-23646WO01 radially compressed prosthetic heart valve 62 on the distal end portion of the delivery shaft 64. In still other examples, the prosthetic heart valve 62 may be mechanically expandable and the prosthetic valve delivery apparatus 60 may include one or more mechanical actuators (e.g., the expansion mechanism) configured to radially expand the prosthetic heart valve 62. As shown in FIG. 3A, the prosthetic heart valve 62 is mounted around the expansion mechanism 65 (the inflatable balloon) on the distal end portion of the delivery shaft 64, in a radially compressed configuration. To navigate the distal end portion of the delivery shaft 64 to the implantation site, the user may insert the prosthetic valve delivery apparatus 60 (the delivery shaft 64) into the patient 10 through the guide catheter 30 and over the guidewire 40. The user may continue to advance the prosthetic valve delivery apparatus 60 along the guidewire 40 (through the blood vessel 12) until the distal end portion of the delivery shaft 64 reaches the native mitral valve 16, as illustrated in FIG. 3A. More specifically, the user may advance the delivery shaft 64 of the prosthetic valve delivery apparatus 60 by gripping and exerting a force on (e.g., pushing) the handle 66. While advancing the delivery shaft 64 through the blood vessel 12 and the heart 14, the user may adjust the one or more articulation members 68 of the handle 66 to navigate the various turns, corners, constrictions, and / or other obstacles in the blood vessel 12 and heart 14. The user may advance the delivery shaft 64 along the guidewire 40 until the radially compressed prosthetic heart valve 62 mounted around the distal end portion of the delivery shaft 64 is positioned within the docking device 52 and the native mitral valve 16. In some examples, as shown in FIG.3A, a distal end of the delivery shaft 64 and a least a portion of the radially compressed prosthetic heart valve 62 may be positioned within the left ventricle 26. Once the radially compressed prosthetic heart valve 62 is appropriately positioned within the docking device 52 (FIG. 3A), the user may manipulate one or more actuation mechanisms of the handle 66 of the prosthetic valve delivery apparatus 60 to actuate the expansion mechanism 65 (e.g., inflate the inflatable balloon), thereby radially expanding the prosthetic heart valve 62 within the docking device 52. FIG. 3B shows a fifth stage in the mitral valve replacement procedure where the prosthetic heart valve 62 is in its radially expanded configuration and implanted within the docking device 52 in the native mitral valve 16. As shown in FIG.3B, the prosthetic heart Attorney Docket No: THVMC-23646WO01 valve 62 is received and retained within the docking device 52. Thus, the docking device 52 aids in anchoring the prosthetic heart valve 62 within the native mitral valve 16. The docking device 52 may enable better sealing between the prosthetic heart valve 62 and the leaflets 24 of the native mitral valve 16 to reduce paravalvular leakage around the prosthetic heart valve 62. As also shown in FIG. 3B, after the prosthetic heart valve 62 has been fully deployed and implanted within the docking device 52 at the native mitral valve 16, the prosthetic valve delivery apparatus 60 (including the delivery shaft 64) is removed from the patient 10 such that only the guidewire 40 and the guide catheter 30 remain inside the patient 10. FIG. 4 depicts a sixth stage in the mitral valve replacement procedure, where the guidewire 40 and the guide catheter 30 have been removed from the patient 10. Although FIGS. 1-4 specifically depict a mitral valve replacement procedure, it should be appreciated that the same and / or similar procedure may be utilized to replace other heart valves (e.g., tricuspid, pulmonary, and / or aortic valves). Further, the same and / or similar delivery apparatuses (e.g., docking device delivery apparatus 50, prosthetic valve delivery apparatus 60, guide catheter 30, and / or guidewire 40), docking devices (e.g., docking device 52), replacement heart valves (e.g., prosthetic heart valve 62), and / or components thereof may be utilized for replacing these other heart valves. For example, when replacing a native tricuspid valve, the user may also access the right atrium 20 via a femoral vein but may not need to cross the atrial septum 22 into the left atrium 18. Instead, the user may leave the guidewire 40 in the right atrium 20 and perform the same and / or similar docking device implantation process at the tricuspid valve. Specifically, the user may push the docking device 52 out of the delivery shaft 54 around the ventricular side of the tricuspid valve leaflets, release the remaining portion of the docking device 52 from the delivery shaft 54 within the right atrium 20, and then remove the delivery shaft 54 of the docking device delivery apparatus 50 from the patient 10. The user may then advance the guidewire 40 through the tricuspid valve into the right ventricle and perform the same and / or similar prosthetic heart valve implantation process at the tricuspid valve, within the docking device 52. Specifically, the user may advance the delivery shaft 64 of the prosthetic valve delivery apparatus 60 through the patient’s vasculature along the guidewire 40 until the prosthetic heart valve 62 is positioned / disposed within the docking device 52 and the tricuspid valve. The user may Attorney Docket No: THVMC-23646WO01 then expand the prosthetic heart valve 62 within the docking device 52 before removing the prosthetic valve delivery apparatus 60 from the patient 10. In another example, the user may perform the same and / or similar process to replace the aortic valve but may access the aortic valve from the outflow side of the aortic valve via a femoral artery. Further, although FIGS. 1-4 depict a mitral valve replacement procedure that accesses the native mitral valve 16 from the left atrium 18 via the right atrium 20 and femoral vein, it should be appreciated that the native mitral valve 16 may alternatively be accessed from the left ventricle 26. For example, the user may access the native mitral valve 16 from the left ventricle 26 via the aortic valve by advancing one or more delivery apparatuses through an artery to the aortic valve, and then through the aortic valve into the left ventricle 26. FIGS. 5 and 6 illustrate a guide catheter, which is referred to below as a guide sheath 100 (but may also be referred to herein as a “delivery apparatus” or an “introducer device”), according to one example. In some examples, the guide sheath 100 may be used as the guide catheter 30 in a prosthetic valve implantation procedure, as described above with reference to FIGS. 1-4, e.g., for a mitral valve replacement procedure or other valve replacement procedure. The guide sheath 100 may be configured to be inserted into a patient’s vasculature and receive an implant catheter (and / or other delivery apparatus) therein to introduce the implant catheter into the patient’s vasculature and at least partially guide the implant catheter to a target implantation site. Examples of implant catheters for prosthetic medical devices (referred to below as “delivery apparatus 200” and “delivery apparatus 300”) that may be received within the guide sheath 100 are shown in FIGS. 7 and 9 respectively, as described further below. Though the guide sheath 100 is described herein as being used with the delivery apparatus 200 and the delivery apparatus 300, the guide sheath 100 may be configured to receive a variety of delivery apparatuses or implant catheters, such as alternate docking device delivery apparatuses, alternate prosthetic heart valve delivery apparatuses, and / or delivery apparatuses for other medical devices or medical therapies. Referring still to FIGS. 5-6, the guide sheath 100 comprises a handle 102, an elongated shaft 104 extending distally from the handle 102, and a central longitudinal axis 112. The shaft 104 has a main (or primary) lumen 122 that is defined by an inner surface of a wall 130 of the shaft 104. The main lumen 122 is configured to receive a delivery apparatus therein (such as any of the prosthetic device delivery apparatuses or implant Attorney Docket No: THVMC-23646WO01 catheters described herein). In some examples, as shown in FIG. 6, the shaft 104 may extend into the handle 102. Further, in some examples, the main lumen 122 may extend through the handle 102 to an inlet port 106 disposed at a proximal end of the handle 102. Thus, in some examples, an inner surface of a wall of a portion of the handle (e.g., at the proximal end) may further define the main lumen 122. Thus, the main lumen 122 may extend from the inlet port 106 to a distal end 108 of the shaft 104. The handle 102 may include a housing 105. Within the housing 105, the handle 102 may include a seal stack 124 and, optionally, a reservoir 132. The seal stack 124 may include a disc cylinder shaped fluid seal comprising a polyisoprene rubber (or other suitable material) disc or cylinder having a slit that may pass through and / or include a center of the fluid seal. Alternatively or additionally, the slit may extend between proximal and distal surfaces of the fluid seal. The seal stack 124, including the fluid seal, may be configured to allow insertion of a device into the handle 102 and prevent fluid flow past the seal stack 124. In addition to a fluid seal, seal stack 124 may comprise a spacer and a cross-slit valve. In some instances, the housing 105 may be integrally formed as a single, unitary component. In other instances, as depicted, the housing 105 may comprise one or more segments that are formed as separate components that are coupled together (e.g., via fasteners, adhesive, mating features (e.g., threads), and / or other means for coupling). For example, the housing 105 may comprise a main segment 105a, a reservoir segment 105b that is proximal to the main segment 105a, and a seal segment 105c that is proximal to the reservoir segment 105b. In the depicted example, the main segment 105a may include steering components, as described in more detail below. The reservoir segment 105b of the housing 105 comprises the reservoir 132. In this manner the segment 105b of the housing 105 may also be referred to as the “reservoir housing.” The seal segment 105c of the housing 105 comprises seal stack 124. In this manner, the segment 105d of the housing 105 may also be referred to as the “seal housing.” The seal stack 124 of the handle 102 may be configured to fluidly seal the main lumen 122 of the guide sheath 100 from the external environment, while allowing a delivery apparatus (such as any of the prosthetic device delivery apparatuses or implant catheters described herein) to pass therethrough. For example, the seal stack 124 of the seal segment 105c may be configured to prevent blood from a patient in which the guide Attorney Docket No: THVMC-23646WO01 sheath 100 is inserted from exiting the guide sheath 100 and prevent air from the environment from entering the guide sheath 100 (e.g., through the inlet port 106), for example, when the delivery apparatus is inserted into and / or removed from the guide sheath 100. The seal stack 124 is further described herein and an example is shown in FIG. 12A, therein depicted as seal stack 600. The reservoir 132 (which may also be referred to as an “air trap”) of the handle 102 is disposed adjacent and distal to the seal segment 105c, and more particularly, distal to the seal stack 124 of the seal segment 105c. The reservoir 132 may include a wall 134 having an inner surface that defines a reservoir lumen 136 extending the length of the reservoir 132. A tube 116 may be connected to the reservoir 132 via a port 126, and further connects to the reservoir lumen 136 (FIG.6). The tube 116 may be configured to receive fluid through a lumen thereof. In this way, the tube 116 may be fluidly coupled to the reservoir lumen 136 by the port 126. The reservoir lumen 136 may be configured to allow air, to the extent any is introduced into the handle 102 as a delivery apparatus is inserted through the seal segment 105c, to accumulate, collect, and / or become trapped within the reservoir lumen 136 of the reservoir 132. Specifically, the reservoir lumen 136 includes an inner diameter IDR that may be greater than an inner diameter IDM of the main lumen 122. In this way, when the handle 102 is positioned in certain orientations (e.g., with the longitudinal axis 112 perpendicular to the direction of gravity, with the port 126 in a vertical direction, etc.), any air introduced through the seal segment 105c gravitates towards the location within the handle 102 having a maximum inner diameter (e.g., the reservoir lumen 136) and may be removed out of the tube 116 via the port 126. In some instances, air that is trapped within reservoir 132 may be removed from the handle 102 to another external location (e.g., a syringe). For example, a syringe may be connected to the tube 116 and used to create a vacuum or negative pressure to remove the air from the reservoir 132 and out of the handle 102 via the port 126 and tube 116. The inner diameter IDRof the reservoir lumen 136 may be measured between two points on the inner surface of the wall 134 in a radial direction relative to the longitudinal axis 112. Similarly, the inner diameter IDMof the main lumen 122 may be measured between two points on the inner surface of the wall 130 in a radial direction relative to the longitudinal axis 112. In some instances, the main lumen 122 may extend through the reservoir 132 and may be defined, in part, by the inner surface of the wall 134 of the Attorney Docket No: THVMC-23646WO01 reservoir 132. In these instances, the reservoir lumen 136 is the portion of the main lumen 122 that is defined by the inner surface of the wall 134 (e.g., within the reservoir 132). As introduced above, the main segment 105a of the handle 102 may include a steering mechanism configured to adjust the curvature of the distal end portion of the shaft 104 (as such, the shaft 104 may be referred to as a steerable shaft). In the illustrated example, the handle 102 includes an adjustment member, such as the illustrated rotatable knob 120. The main segment 105a may house internal flex mechanisms 128 of the guide sheath 100 which are operatively coupled to the rotatable knob 120 (FIG. 6). In some examples, the flex mechanisms 128, and thus the knob 120, may be operatively coupled to the proximal end portion of a pull wire. The pull wire may extend distally from the handle 102 through the shaft 104 and have a distal end portion affixed to the shaft 104 at or near the distal end 108 of the shaft 104. Rotating the knob 120 may increase or decrease the tension in the pull wire, thereby adjusting the curvature of the distal end portion of the shaft 104. Further details on example steering or flex mechanisms for a delivery apparatus are found in U.S. Patent No.9,339,384, which is incorporated by reference herein. The main segment 105a of the handle 102 may include a connector 114 (also referred to herein as an “adaptor spine”) disposed adjacent and distal to the reservoir 132. The handle 102 may include one or more gaskets 115 (e.g., o-rings and / or other types of sealing components) disposed between adjacent components to seal any gaps between surfaces of the adjacent components. As shown in FIG. 6, the handle 102 includes a first gasket 115 disposed adjacent and distal to the seal segment 105c and a second gasket 115 disposed adjacent and distal to the reservoir 132. It should be noted that the size of the gaskets 115 shown in FIG.6 may be exaggerated for the purpose of illustration. In some examples, the width of the gaskets 115 may be smaller than shown in FIG.6. FIG.7 illustrates a delivery apparatus 200 configured to implant a docking device, such as docking device 240 (FIG.8) described below or other docking devices, to a target implantation site in a patient, according to one example. For example, the delivery apparatus 200 may be used as the docking device delivery apparatus 50 in a prosthetic valve implantation procedure, as described above with reference to FIG.2A. The delivery apparatus 200 may also be referred to as a “dock delivery catheter” or “dock delivery system.” As shown, the delivery apparatus 200 may include a handle assembly 202 and a delivery sheath 204 (also referred to as the “delivery shaft” or “outer shaft” or “outer Attorney Docket No: THVMC-23646WO01 sheath”) extending distally from the handle assembly 202. The handle assembly 202 may include a handle 206 including one or more knobs, buttons, wheels, and / or other means for controlling and / or actuating one or more components of the delivery apparatus 200. For example, in some examples, as shown in FIG. 7, the handle 206 may include knobs 208 and 210 which may be configured to steer or control flexing of the delivery apparatus 200 such as the delivery sheath 204 and / or the sleeve shaft 220 described below. In certain examples, the delivery apparatus 200 may also include a pusher shaft 212 and a sleeve shaft 220, both of which may extend through an inner lumen of the delivery sheath 204 and have respective proximal end portions extending into the handle assembly 202. As described below, a distal end portion (also referred to as “distal section”) of the sleeve shaft 220 may be configured to cover (e.g., surround) the docking device 240 (see FIG.8). For example, the docking device 240 may be retained inside the sleeve shaft 220, which is further retained by a distal end portion 205 of the delivery sheath 204, when navigating through a patient’s vasculature. Additionally, the distal end portion 205 of the delivery sheath 204 may be configured to be steerable. In one example, by rotating a knob (e.g., 208 or 210) on the handle 206, a curvature of the distal end portion 205 may be adjusted so that the distal end portion 205 of the delivery sheath 204 may be oriented in a desired angle. For example, to implant the docking device 240 at the native mitral valve location, the distal end portion 205 of the delivery sheath 204 may be steered in the left atrium so that at least a portion of the sleeve shaft 220 and the docking device 240 retained therein may extend through the native mitral valve annulus at a location adjacent the posteromedial commissure. In certain examples, the pusher shaft 212 and the sleeve shaft 220 may be coaxial with one another, at least within the delivery sheath 204. In addition, the delivery sheath 204 may be configured to be axially movable relative to the sleeve shaft 220 and the pusher shaft 212. As described further below, a distal end of the pusher shaft 212 may be inserted into a lumen of the sleeve shaft 220 and press against the proximal end of the docking device 240 retained inside the sleeve shaft 220. After reaching a target implantation site, the docking device 240 may be deployed from the delivery sheath 204 by manipulating the pusher shaft 212 and sleeve shaft 220 using a hub assembly 218, as described further below. For example, by pushing the pusher shaft 212 in the distal direction while holding the delivery sheath 204 in place or retracting Attorney Docket No: THVMC-23646WO01 the delivery sheath 204 in the proximal direction while holding the pusher shaft 212 in place, or pushing the pusher shaft 212 in the distal direction while simultaneously retracting the delivery sheath 204 in the proximal direction, the docking device 240 may be pushed out of a distal end 204d of the delivery sheath 204, thus changing from a delivery configuration to a deployed configuration (see FIG. 8). In certain examples, the pusher shaft 212 and the sleeve shaft 220 may be actuated independently of each other. During delivery, the docking device 240 may be coupled to the delivery apparatus 200 via a release suture (not shown) (or other retrieval line comprising a string, yarn, or other material that may be configured to be tied around the docking device 240 and cut for removal) that extends through the pusher shaft 212. In one specific example, the release suture may extend through the delivery apparatus 200, e.g., through an inner lumen of the pusher shaft 212, to a suture lock assembly 216 of the delivery apparatus 200. The handle assembly 202 may further include a hub assembly 218 to which the suture lock assembly 216 and a sleeve handle 224 are attached. The hub assembly 218 may be configured to independently control the pusher shaft 212 and the sleeve shaft 220 while the sleeve handle 224 may control an axial position of the sleeve shaft 220 relative to the pusher shaft 212. In this way, operation of the various components of the handle assembly 202 may actuate and control operation of the components arranged within the delivery sheath 204. In some examples, the hub assembly 218 may be coupled to the handle 206 via a connector 226. The handle assembly 202 may further include one or more flush ports (e.g., flush port 232 is shown in FIG. 7) to supply flush fluid to one or more lumens arranged within the delivery apparatus 200 (e.g., annular lumens arranged between coaxial components of the delivery apparatus 200). Further details on example delivery apparatus / catheters / systems (including various examples of the handle assembly) that are configured to deliver a docking device to a target implantation site may be found in International Application No. PCT / US2020 / 036577 and in U.S. Patent Publication Nos. 2018 / 0318079 and 2018 / 0263764, which are all incorporated by reference herein in their entireties. FIG. 8 illustrates a docking device 240, according to one example. The docking device 240 can, for example, be used as the docking device 52 in a prosthetic valve implantation procedure, as described above with reference to FIGS. 1-4. As depicted in FIG.8, the docking device in its deployed configuration may be configured to receive and Attorney Docket No: THVMC-23646WO01 secure a prosthetic valve within the docking device, thereby securing the prosthetic valve at the native valve annulus. The docking device 240 may comprise a coil 242 and a guard member 244 covering at least a portion of the coil 242. In certain examples, the coil 242 may include a shape memory material (e.g., nickel titanium alloy or “Nitinol”) such that the docking device 240 (and the coil 242) may move from a substantially straight configuration (or delivery configuration) when disposed within the delivery sheath 204 of the delivery apparatus 200 to a helical, deployed configuration after being removed from the delivery sheath 204. The coil 242 has a proximal end 242p and a distal end 242d (which also respectively define the proximal and distal ends of the docking device 240). When being disposed within the delivery sheath 204 (e.g., during delivery of the docking device 240 into the vasculature of a patient), a body of the coil 242 between the proximal end 242p and distal end 242d may form a generally straight delivery configuration (i.e., without any coiled or looped portions, but may be flexed or bent) so as to maintain a small radial profile when moving through a patient’s vasculature. After being removed from the delivery sheath 204 and deployed at an implant position, the coil 242 may move from the delivery configuration to the helical deployed configuration and wrap around native tissue adjacent the implant position. For example, when implanting the docking device at the location of a native valve, the coil 242 may be configured to surround native leaflets of the native valve (and the chordae tendineae that connects native leaflets to adjacent papillary muscles, if present). The docking device 240 may be releasably coupled to the delivery apparatus 200. For example, in certain examples, the docking device 240 may be coupled to a delivery apparatus (as described above) via a release suture that may be configured to be tied to the docking device 240 and cut for removal. As shown in FIG. 8, the coil 242 in the deployed configuration may include a leading turn 246 (or “leading coil”), a central region 248, and a stabilization turn 250 (or “stabilization coil”) around a central longitudinal axis. The central region 248 may possess one or more helical turns having substantially equal inner diameters. The leading turn 246 may extend from a distal end of the central region 248 and has a diameter greater than the diameter of the central region 248, in the illustrated example. The stabilization turn 250 may extend from a proximal end of the central region 248 and has a diameter greater than the diameter of the central region 248, in the illustrated example. Attorney Docket No: THVMC-23646WO01 Further details of examples of the docking device 240 and its variants are described in International Application No. PCT / US2021 / 056150, which is incorporated by reference herein in its entirety. FIG.9 illustrates a prosthetic heart valve delivery apparatus 300 (which may also be referred to here as an “implant catheter”) that may be used to implant an expandable prosthetic heart valve, according to one example. In some examples, the delivery apparatus 300 is specifically adapted for use in introducing a prosthetic heart valve into a heart. For example, the delivery apparatus 300 may be used as the prosthetic heart valve delivery apparatus 60 in a prosthetic valve implantation procedure, as described above with reference to FIG.3A. The delivery apparatus 300 in the illustrated example of FIG.9 is a balloon catheter comprising a handle 302 and a steerable, outer shaft 304 extending distally from the handle 302. The delivery apparatus 300 may further comprise an intermediate shaft 306 (which also may be referred to as a balloon shaft) that extends proximally from the handle 302 and distally from the handle 302, the portion extending distally from the handle 302 also extending coaxially through the outer shaft 304. In some examples, the delivery apparatus 300 may further comprise an inner shaft extending distally from the handle 302 coaxially through the intermediate shaft 306 and the outer shaft 304 and proximally from the handle 302 coaxially through the intermediate shaft 306. The outer shaft 304 and the intermediate shaft 306 may be configured to translate (e.g., move) longitudinally, along a central longitudinal axis 320 of the delivery apparatus 300, relative to one another to facilitate delivery and positioning of a prosthetic valve at an implantation site in a patient’s body. The intermediate shaft 306 may include a proximal end portion that extends proximally from a proximal end of the handle 302, to an adaptor 312. The adaptor 312 may include a first port 338 configured to receive a guidewire therethrough and a second port 340 configured to receive fluid (e.g., inflation fluid) from a fluid source. The second port 340 may be fluidly coupled to an inner lumen of the intermediate shaft 306. In some examples, the intermediate shaft 306 may further include a distal end portion that extends distally beyond a distal end of the outer shaft 304 when a distal end of the outer shaft 304 is positioned away from an inflatable balloon 318 of the delivery apparatus 300. A distal end portion of the inner shaft may extend distally beyond the distal Attorney Docket No: THVMC-23646WO01 end portion of the intermediate shaft 306 toward or to a nose cone 322 at a distal end of the delivery apparatus 300. In some examples, a distal end of the balloon 318 may be coupled to a distal end of the delivery apparatus 300, such as to the nose cone 322 (as shown in FIG.9), or to an alternate component at the distal end of the delivery apparatus 300 (e.g., a distal shoulder). An intermediate portion of the balloon 318 may overlay a valve mounting portion 324 of a distal end portion of the delivery apparatus 300 and a distal end portion of the balloon 318 may overly a distal shoulder of the delivery apparatus 300. As shown in FIG. 9, a prosthetic heart valve 350 may be mounted around the balloon 318, at the valve mounting portion 324 of the delivery apparatus 300, in a radially compressed state. The prosthetic heart valve 350 may be configured to be radially expanded by inflation of the balloon 318 at a native valve annulus, as described above with reference to FIG.3A. A balloon shoulder assembly of the delivery apparatus 300, which includes the distal shoulder, is configured to maintain the prosthetic heart valve 350 (or other medical device) at a fixed position on the balloon 318 during delivery through the patient’s vasculature. The outer shaft 304 may include a distal tip portion 328 mounted on its distal end. In some examples, the outer shaft 304 and the intermediate shaft 306 may be translated axially relative to one another to position the distal tip portion 328 adjacent to a proximal end of the valve mounting portion 324, when the prosthetic valve 350 is mounted in the radially compressed state on the valve mounting portion 324 (as shown in FIG. 9) and during delivery of the prosthetic valve to the target implantation site. As such, the distal tip portion 328 may be configured to resist movement of the prosthetic valve 350 relative to the balloon 318 proximally, in the axial direction, relative to the balloon 318, when the distal tip portion 328 is arranged adjacent to a proximal side of the valve mounting portion 324. An annular space may be defined between an outer surface of the inner shaft and an inner surface of the intermediate shaft 306 and may be configured to receive fluid from a fluid source via the second port 340 of the adaptor 312. The annular space may be fluidly coupled to a fluid passageway formed between the outer surface of the distal end portion of the inner shaft and an inner surface of the balloon 318. As such, fluid from the fluid source may flow to the fluid passageway from the annular space to inflate the balloon 318 and radially expand and deploy the prosthetic valve 350. Attorney Docket No: THVMC-23646WO01 An inner lumen of the inner shaft may be configured to receive a guidewire therethrough, for navigating the distal end portion of the delivery apparatus 300 to the target implantation site. The handle 302 may include a steering mechanism configured to adjust the curvature of the distal end portion of the delivery apparatus 300. In the illustrated example, for example, the handle 302 includes an adjustment member, such as the illustrated rotatable knob 360, which in turn is operatively coupled to the proximal end portion of a pull wire. The pull wire may extend distally from the handle 302 through the outer shaft 304 and has a distal end portion affixed to the outer shaft 304 at or near the distal end of the outer shaft 304. Rotating the knob 360 may increase or decrease the tension in the pull wire, thereby adjusting the curvature of the distal end portion of the delivery apparatus 300. Further details on example steering or flex mechanisms for the delivery apparatus may be found in U.S. Patent No.9,339,384, as previously incorporated by reference above. The handle 302 may further include an adjustment mechanism 361 including an adjustment member, such as the illustrated rotatable knob 362, and an associated locking mechanism including another adjustment member, configured as a rotatable knob 378. The adjustment mechanism 361 is configured to adjust the axial position of the intermediate shaft 306 relative to the outer shaft 304 (e.g., for fine positioning at the implantation site). FIG. 10 illustrates the prosthetic valve 350 in a radially expanded position. The prosthetic valve 350 may be used as the prosthetic heart valve 62 in a prosthetic valve implantation procedure, as described above with reference to FIGS. 1-4. The prosthetic valve 350 may include a frame 352 and a plurality of leaflets 354 may be situated at least partially within the frame 352. The prosthetic valve 350 may also include an outer covering 356 situated about the frame 352. Further details of examples of the prosthetic heart valve and its variants are described in U.S. Patent No. 11,185,406, which is incorporated by reference herein in its entirety. As noted above, the delivery apparatus 200 and / or the delivery apparatus 300 may be introduced into a patient’s vasculature via a guide catheter, such as the guide sheath 100 of FIGS.5 and 6. For example, to introduce the delivery apparatus 200 and / or 300 (or an alternate implant catheter or delivery apparatus) into the vasculature of a patient, the shaft 104 of the guide sheath 100 may first be inserted into the patient’s vasculature and navigated through the vasculature toward a target implantation site for a medical device or Attorney Docket No: THVMC-23646WO01 implant. The handle 102 of the guide sheath 100 remains outside the patient and may be accessed by a user (e.g., a physician). The distal end portion 205 of the delivery apparatus 200 and / or the distal end portion of the delivery apparatus 300 (e.g., the nose cone 322 and radially compressed prosthetic heart valve 350 of the delivery apparatus 300) may then be inserted into the inlet port 106 of the handle 102 of the guide sheath 100. The distal end portion of the delivery apparatus 200 and / or 300 is then pushed through the seal segment 105c (e.g., through seal stack 124) and into the reservoir 132 of the guide sheath 100. The delivery apparatus 200 and / or 300 may then continue to be pushed through the inner lumen of the shaft 104, toward the implantation site. As mentioned above, it is possible for air to be introduced within the system when the delivery apparatus 200 and / or 300 is inserted into the guide sheath 100 in some examples. To prevent any air that may have entered the system from advancing distally through the system, it may be advantageous to provide a reservoir of fluid which is configured to trap the air within the reservoir, such that the trapped air may be removed and / or aspirated out of the system from the reservoir. Referring again to FIGS.5 and 6, the reservoir 132 of the guide sheath 100 may be configured to prevent air (to the extent any has entered the system) from advancing further (or distally) into the system (e.g., distal to the reservoir 132, etc.). Specifically, as described above, the reservoir 132 may be located within the reservoir segment 105b of the handle 102 and may be positioned distal to the seal segment 105c. As noted above, the inner diameter IDR of the reservoir lumen 136 may be larger than the inner diameter IDM of the main lumen 122. Because of the difference in inner diameter, any air that is introduced by way of a delivery apparatus (e.g., delivery apparatus 200 and / or 300) being inserted through the seal segment 105c may be trapped within the reservoir and prevented from traveling distally through the guide sheath 100. Any air trapped within the reservoir 132 may be aspirated or removed through the tube 116 via the port 126 (e.g., using a syringe). As shown in FIG.6, the inner diameter IDR of the reservoir lumen 136 is a constant value from a proximal end of the reservoir 132 to a distal end of the reservoir 132 (e.g., the reservoir lumen 136 is a straight bore, etc.). It should be appreciated that in other instances, the inner diameter IDRof the reservoir lumen 136 may vary (e.g., increase in a proximal direction, etc.) such that the reservoir lumen 136 may include one or more tapers (e.g., a tapered or frustoconical portion, etc.), steps, or the like. Attorney Docket No: THVMC-23646WO01 The reservoir lumen 136 may have a circular cross-section. In some instances, the cross-section of the reservoir lumen 136 may include other shapes, including but not limited to round shapes such as ovals, ellipses, etc. and / or polygonal shapes such as squares, rectangles, etc. For example, in some instances, the reservoir lumen 136 may be generally cylindrical and include an axially extending slot disposed in a radially spaced position from the longitudinal axis 112. Further, in some instances, the cross-section of the reservoir lumen 136 may be asymmetrical (e.g., such that a central longitudinal axis of the reservoir lumen 136 is not coaxial with the longitudinal axis 112 of the guide sheath 100). It should be appreciated that in instances where the cross-section of the reservoir lumen 136 is non-circular, the inner diameter IDR refers to a greatest measurement (e.g., length, width, diagonal, etc.) of the cross-section (e.g., a measurement between two points on the inner surface of the wall 134 in a radial direction relative to the longitudinal axis 112, etc.). In some examples, the reservoir 132 may be a transparent or translucent material (e.g., a clear polycarbonate material, etc.) to enable a user of the guide sheath to visually inspect whether any air has entered the system (e.g., after insertion of a delivery apparatus, etc.). The port 126 may be perpendicular to the longitudinal axis 112, as shown in FIG. 6. In some examples, the port 126 may be positioned at a different angle with respect to the longitudinal axis 112 (e.g., angled toward the proximal end 132p of the reservoir 132, etc.). FIG. 11 shows an example of a reservoir 632 (or air trap) of a handle of a guide sheath (e.g., similar to guide sheath 100, 400, 500) that is configured to prevent air (to the extent any has entered the system) from advancing further (or distally) into the system, whereby any air trapped within the reservoir 632 may be removed through a flush port via a flush lumen 626. The reservoir 632 may be similar to, e.g., the reservoir 132 of FIGS.5- 6. Thus, common components between the reservoir 632 and the reservoir 132 are labeled similarly in FIG. 11 and not redescribed below, for the sake of brevity. Additionally, components described below in connection with the reservoir 632 may also be included in the reservoir 132. The reservoir 632 may include an inlet 650 at a proximal end of the reservoir 632 and an outlet 652 at a distal end of the reservoir 632. The inlet 650 may provide an entryway into the reservoir lumen 636 to allow insertion of a delivery apparatus (such as any of the prosthetic device delivery apparatuses or implant catheters described herein) Attorney Docket No: THVMC-23646WO01 into the reservoir lumen 636. The inlet 650 (or the proximal end) of the reservoir 632 is configured for attachment to a seal housing assembly of a handle (e.g., seal segment 105c, etc.) and the outlet 652 (or distal end) of the reservoir 632 is configured for attachment to a main body portion of a handle (e.g., main body portion 118 via connector 114). Specifically, the inlet 650 and the outlet 652 may include a plurality of attachment points 654 (e.g., holes, threaded holes, etc.) which are configured to receive fasteners (e.g., screws, etc.) (not shown) to enable the reservoir 632 to be coupled at an intermediate position within a handle (e.g., distal to a seal housing assembly, etc.). In the illustrated example, the flush lumen 626 is disposed near the proximal end of the reservoir 632. It should be appreciated that in other examples, the flush lumen 626 may be disposed in other positions on the reservoir 632 (e.g., near the distal end of the reservoir 632, at a maximum inner diameter of the reservoir lumen 636, etc.). In this way, the reservoirs (or air traps) of the delivery apparatuses described above with reference to FIGS.5-6 may provide a location for air (to the extent any is introduced into the delivery apparatuses) to accumulate and / or become trapped as implant catheters and other devices are being navigated through the delivery apparatuses. In some examples, air may enter a delivery apparatus as an implant catheter is inserted into a seal housing assembly at a proximal end of a handle of the delivery apparatus. The air may then accumulate and become trapped (e.g., prevented from travelling distally through the handle, etc.) within a reservoir of the handle that is positioned adjacent and distal to the seal housing assembly. As a result of the air becoming trapped within the reservoir, the air may be removed and / or aspirated from the reservoir via a flush port. In some examples, this may increase an efficiency of a prosthetic device implantation procedure. FIG.12A is an exploded perspective view of the seal stack 600 for a guide catheter, according to one example. The seal stack 600 comprises the fluid seal 602, the spacer 603, and the cross-slit valve 604 as described herein. In some embodiments, the spacer 603 may be a rigid plastic component comprising black ABS material. The spacer 603 may be an injection-molded component used to provide structural support and fitment for the other components (e.g., fluid seal 602 and cross-slit valve 604) retained inside the guide sheath seal housing assembly and serve as a compression force for retention of the seal stack. The spacer 603 may fit the cross-slit valve 604 and provide peripheral structural integrity for the seal stack components that reside inside the seal stack housing, which may be Attorney Docket No: THVMC-23646WO01 comprised of polycarbonate. The spacer 603 is typically a rigid circular component with a hollow central diameter. In some embodiments, the spacer 603 may have an outer diameter that is the same as, or similar to, that of the fluid seal 602, e.g., a diameter of about 0.5-1 inches, such as about 0.75 inches. In some embodiments, the spacer 603 may have an inner diameter that is about 50-95%, about 70-90%, or about 80%, of the outer diameter of the spacer 603, such as about 0.4-0.9 inches or about 0.6 inches. The inner diameter of the spacer 603 may be sized to house the minor outer diameter portion 607 of the cross-slit valve 604 so that the minor outer diameter portion 607 of the cross-slit valve 604 fits snugly inside the inner diameter of the spacer 603. The minor outer diameter portion 607 of the cross-slit valve 604 may be shaped to fit snugly into the interior of the spacer 603 so that the minor outer diameter portion 607 of the cross-slit valve 604 fits snugly against the proximal surface of the fluid seal 602. For example, the minor outer diameter portion 607 of the cross-slit valve 604 may have an outer diameter of about 0.4-0.9 inches or about 0.6 inches, and a thickness of about 0.2-0.4 inches, or about 0.3 inches. The spacer 603 may have an axial thickness or length that accommodates the minor outer diameter portion 607 of the cross-slit valve 604, so that the distal end of the cross-slit valve 604 fits snugly against the proximal surface of the fluid seal 602. In some embodiments, the spacer 603 has an axial thickness or length of about 0.2-0.4 inches, or about 0.3 inches. FIG. 12B is a perspective view of fluid seal assembly 608 for a guide catheter, according to one example. As depicted in FIG 12B, the fluid seal assembly 608 comprises the cross-slit valve 604, and particularly the minor outer diameter portion 607 of cross-slit valve 604, fitting snugly inside the inner diameter of spacer 603, and the fluid seal 602 fitting snugly against the distal surface of the minor outer diameter portion 607 of the cross-slit valve 604. FIGS. 13A, 13B, and 13C respectively include a perspective view, a distal view (e.g., a view of the distal side or surface), and a cross-sectional side view of the fluid seal 602 of FIGS.12A-12B. The cross-sectional side view of FIG.13C is taken along cutting plane A-A in FIG.13B. As illustrated in FIGS. 13A-13C, the fluid seal 602 defines a slit (or coin slit) 605 that extends from a distal surface 606d of the fluid seal 602 completely through the fluid seal 602 to a proximal surface 606p of the fluid seal 602. Although not necessarily visible in use, dashed lines in FIG.13A depict the extent of the slit 605 through the fluid seal 602 to the proximal surface 606p. FIG.13C depicts dimensions of the fluid Attorney Docket No: THVMC-23646WO01 seal 602 in an example embodiment, i.e., 0.125 inches thick (in the axial direction) and 0.750 inches in diameter as illustrated. In some embodiments, the fluid seal 602 may have a thickness of about 1 / 16-1 / 4 inches, or about 0.05-0.2 inches, such as about 1 / 8 inch or about 0.125 inches, and a diameter of about 0.5-1 inches, such as about 0.75 inches. The fluid seal 602 may define a single slit 605 that passes completely through the fluid seal 602. In some embodiments, the slit 605 may have a length (i.e., in the horizontal direction in FIG.13B) of about 1 / 16- 1 / 3 inches, or about 0.1-0.3 inches, such as about 0.217 inches. Thus, the new seal assembly provides a guide sheath the ability to execute an aspiration function without needing another catheter to bridge the seals. If this aspiration was performed in a conventional guide sheath with the existing prior art seals, air may be pulled into the guide sheath without a catheter in between them. Thus, the catheter bridging the seals aspiration technique adds multiple extra steps to the conventional procedures. Minimizing the number of steps may simplify the procedure while also reducing the air emboli risk to the patient while the guide sheath is being used throughout the duration of the procedure. Therefore, these slit seals and new slit seal assembly is an improvement to current prior art seals. Delivery Techniques For implanting a prosthetic valve within the native aortic valve via a transfemoral delivery approach, the prosthetic valve is mounted in a radially compressed state along the distal end portion of a delivery apparatus. The prosthetic valve and the distal end portion of the delivery apparatus are inserted into a femoral artery and are advanced into and through the descending aorta, around the aortic arch, and through the ascending aorta. The prosthetic valve is positioned within the native aortic valve and radially expanded (e.g., by inflating a balloon, actuating one or more actuators of the delivery apparatus, or deploying the prosthetic valve from a sheath to allow the prosthetic valve to self-expand). Alternatively, a prosthetic valve may be implanted within the native aortic valve in a transapical procedure, whereby the prosthetic valve (on the distal end portion of the delivery apparatus) is introduced into the left ventricle through a surgical opening in the chest and the apex of the heart and the prosthetic valve is positioned within the native aortic valve. Alternatively, in a transaortic procedure, a prosthetic valve (on the distal end portion of the delivery apparatus) is introduced into the aorta through a surgical incision in the ascending aorta, such as through a partial J-sternotomy or right parasternal mini- Attorney Docket No: THVMC-23646WO01 thoracotomy, and then advanced through the ascending aorta toward the native aortic valve. For implanting a prosthetic valve within the native mitral valve via a transseptal delivery approach, the prosthetic valve is mounted in a radially compressed state along the distal end portion of a delivery apparatus. The prosthetic valve and the distal end portion of the delivery apparatus are inserted into a femoral vein and are advanced into and through the inferior vena cava, into the right atrium, across the atrial septum (through a puncture made in the atrial septum), into the left atrium, and toward the native mitral valve. Alternatively, a prosthetic valve may be implanted within the native mitral valve in a transapical procedure, whereby the prosthetic valve (on the distal end portion of the delivery apparatus) is introduced into the left ventricle through a surgical opening in the chest and the apex of the heart and the prosthetic valve is positioned within the native mitral valve. For implanting a prosthetic valve within the native tricuspid valve, the prosthetic valve is mounted in a radially compressed state along the distal end portion of a delivery apparatus. The prosthetic valve and the distal end portion of the delivery apparatus are inserted into a femoral vein and are advanced into and through the inferior vena cava, and into the right atrium, and the prosthetic valve is positioned within the native tricuspid valve. A similar approach may be used for implanting the prosthetic valve within the native pulmonary valve or the pulmonary artery, except that the prosthetic valve is advanced through the native tricuspid valve into the right ventricle and toward the pulmonary valve / pulmonary artery. Another delivery approach is a transatrial approach whereby a prosthetic valve (on the distal end portion of the delivery apparatus) is inserted through an incision in the chest and an incision made through an atrial wall (of the right or left atrium) for accessing any of the native heart valves. Atrial delivery may also be made intravascularly, such as from a pulmonary vein. Still another delivery approach is a transventricular approach whereby a prosthetic valve (on the distal end portion of the delivery apparatus) is inserted through an incision in the chest and an incision made through the wall of the right ventricle (typically at or near the base of the heart) for implanting the prosthetic valve within the native tricuspid valve, the native pulmonary valve, or the pulmonary artery. In all delivery approaches, the delivery apparatus may be advanced over a guidewire previously inserted into a patient’s vasculature. Moreover, the disclosed Attorney Docket No: THVMC-23646WO01 delivery approaches are not intended to be limited. Any of the prosthetic valves disclosed herein may be implanted using any of various delivery procedures and delivery devices known in the art. Additional Examples of the Disclosed Technology In view of the above-described implementations of the disclosed subject matter, this application discloses the additional examples enumerated below. It should be noted that one feature of an example in isolation or more than one feature of the example taken in combination and, optionally, in combination with one or more features of one or more further examples are further examples also falling within the disclosure of this application. Example 1. A delivery apparatus comprising: a seal housing assembly including a seal housing and a seal stack disposed within the seal housing; wherein the seal stack comprises a fluid seal having a first surface, having a circular shape, and a second surface, having a circular shape, disposed opposite to the first surface; and wherein the fluid seal defines a slit extending from the first surface to the second surface through centers of the first and second surfaces. Example 2. The delivery apparatus of any example herein, wherein the seal stack further comprises a spacer disposed proximately to the fluid seal and in contact with the first surface of the fluid seal or the second surface of the fluid seal. Example 3. The delivery apparatus of any example herein, wherein the seal stack further comprises a cross-slit valve, wherein at least a portion of the cross-slit valve is disposed proximately to the spacer and in contact with the spacer. Example 4. The delivery apparatus of any example herein, wherein the delivery apparatus is a guide catheter. Example 5. The delivery apparatus of any example herein, wherein the fluid seal comprises a polyisoprene material. Example 6. The delivery apparatus of any example herein, wherein the fluid seal comprises polyisoprene rubber. Example 7. The delivery apparatus of any example herein, wherein the fluid seal is cylindrical. Example 8. The delivery apparatus of any example herein, wherein the fluid seal comprises elastomeric silicone. Example 9. The delivery apparatus of any example herein, wherein the fluid seal comprises liquid silicone rubber. Attorney Docket No: THVMC-23646WO01 Example 10. The delivery apparatus of any example herein, wherein the fluid seal comprises high consistency rubber. Example 11. The delivery apparatus of any example herein, wherein the fluid seal has a Shore hardness in a range from 25 A to 50 A. Example 12. The delivery apparatus of any example herein, wherein the fluid seal has a Shore hardness in a range from 40 A to 50 A. Example 13. The delivery apparatus of any example herein, wherein the slit is configured to prevent entry of fluid through the fluid seal. Example 14. The delivery apparatus of any example herein, further comprising: a handle comprising: a proximal segment comprising the seal housing assembly, the seal stack configured to allow insertion of a device into the handle and prevent fluid flow past the seal stack; an intermediate segment disposed adjacent and distal to the proximal segment, the intermediate segment including an inner surface defining a first lumen, wherein the first lumen has a first inner diameter, wherein the first lumen includes an inlet and an outlet; and a distal segment disposed adjacent and distal to the intermediate segment; and a shaft extending distally from the handle, the shaft including a distal end, a proximal end, and a second lumen extending between the distal end and the proximal end of the shaft, wherein the proximal end of the shaft is disposed within the distal segment of the handle and is coupled to the outlet of the first lumen, wherein the second lumen includes a second inner diameter that is less than the first inner diameter of the first lumen. Example 15. The delivery apparatus of any example herein, wherein the first lumen and the second lumen are coaxial. Example 16. The delivery apparatus of any example herein, wherein the inlet of the first lumen is coupled to the proximal segment of the handle. Example 17. The delivery apparatus of any example herein, wherein the inner surface includes at least one taper. Example 18. The delivery apparatus of any example herein, wherein the inner surface includes a band having a constant inner diameter equal to the first inner diameter. Example 19. The delivery apparatus of any example herein, wherein the band extends from the inlet of the first lumen to the outlet of the first lumen. Example 20. The delivery apparatus of any example herein, wherein the inner surface includes a band, the band includes a distal end and a proximal end, and the inner surface is tapered from the distal end of the band to the outlet of the first lumen. Attorney Docket No: THVMC-23646WO01 Example 21. The delivery apparatus of any example herein, wherein the inner surface includes a step disposed between the inlet of the first lumen and the proximal end of the band. Example 22. The delivery apparatus of any example herein, wherein the inner surface includes a band, the band includes a distal end and a proximal end, and the inner surface is tapered from the proximal end of the band to the inlet of the first lumen. Example 23. The delivery apparatus of any example herein, further comprising a flush port coupled to the intermediate segment, the flush port fluidly coupled to the first lumen via a flush lumen. Example 24. The delivery apparatus of any example herein, wherein an inner diameter of the outlet of the first lumen is equal to the second inner diameter. Example 25. The delivery apparatus of any example herein, wherein an inner diameter of the inlet of the first lumen is equal to the second inner diameter. Example 26. The delivery apparatus of any example herein, wherein the intermediate segment is transparent or translucent. Example 25. A delivery apparatus comprising: a handle comprising: a proximal segment comprising a seal housing assembly comprising a seal housing and a seal stack disposed within the seal housing, the seal stack configured to allow insertion of a device into the handle and prevent fluid flow past the seal stack; an intermediate segment disposed adjacent and distal to the proximal segment, the intermediate segment including an inner surface defining a first lumen; and a distal segment disposed adjacent and distal to the intermediate segment; and a shaft extending distally from the handle, the shaft including a distal end, a proximal end, and a second lumen extending between the distal end and the proximal end of the shaft, wherein the proximal end of the shaft is disposed within the distal segment of the handle and is coupled to the first lumen; wherein the seal stack comprises a fluid seal having a distal surface, having a circular shape, and a proximal surface, having a circular shape, disposed opposite to the distal surface; and wherein the fluid seal defines a slit extending from the distal surface to the proximal surface through centers of the distal and proximal surfaces. Example 26. The delivery apparatus of any example herein, wherein the seal stack further comprises a spacer disposed proximately to the fluid seal and in contact with the proximal surface of the fluid seal. Attorney Docket No: THVMC-23646WO01 Example 27. The delivery apparatus of any example herein, wherein the seal stack further comprises a cross-slit valve, wherein at least a portion of the cross-slit valve is disposed proximately to the spacer and in contact with the spacer. Example 28. The delivery apparatus of any one of any example herein, wherein the fluid seal comprises at least one of: a polyisoprene material; polyisoprene rubber; elastomeric silicone; liquid silicone rubber; or high consistency rubber. Example 29. The delivery apparatus of any one of any example herein, wherein the fluid seal has a Shore hardness in a range from 25 A to 50 A. Example 30. The delivery apparatus of any one of any example herein, wherein the fluid seal has a Shore hardness in a range from 40 A to 50 A. Example 31. The delivery apparatus of any one of any example herein, wherein the slit is configured to prevent entry of fluid through the fluid seal. Example 32. The delivery apparatus of any one of any example herein, wherein the intermediate segment comprises a reservoir including a reservoir lumen and at least a portion of the reservoir has a first diameter that is greater than a second diameter of the second lumen. Example 33. The delivery apparatus of any example herein, wherein the intermediate segment further comprises a flush lumen in fluid communication with the reservoir lumen, the delivery apparatus further comprising a flush port fluidly coupled to the flush lumen. Example 34. The delivery apparatus of any example herein, wherein the reservoir lumen includes at least one of a cylindrical portion or a frustoconical portion. Example 35. A method for implanting a prosthetic medical device, comprising: inserting a shaft of a guide catheter into a vessel of a patient; and inserting a distal end portion of a first implant catheter into a proximal end of a handle of the guide catheter and pushing the distal end portion of the first implant catheter through a seal stack of the handle and then through a main lumen of the shaft of the guide catheter toward a target implantation site for a prosthetic medical device mounted on the distal end portion of the first implant catheter; wherein the seal stack is configured to allow insertion of a device into the handle and prevent fluid flow past the seal stack; wherein the seal stack comprises a fluid seal having a first surface, having a circular shape, and a second surface, having a circular shape, disposed opposite to the first surface; and wherein the fluid seal defines a Attorney Docket No: THVMC-23646WO01 slit extending from the first surface to the second surface through centers of the first and second surfaces. Example 36. The method of any example herein, wherein the shaft of the guide catheter extends into the handle of the guide catheter which remains exterior to the patient while a portion of the shaft extending distally from the handle is disposed within the vessel. Example 37. The method of any example herein, wherein a flush port is disposed distal to one or more fluid seals of the handle that are disposed adjacent to the proximal end of the guide catheter. Example 38. The method of any example herein, further comprising implanting the prosthetic medical device at the target implantation site, removing the first implant catheter from the guide catheter, and inserting a second implant catheter into the guide catheter and pushing the second implant catheter through the seal stack and through the main lumen toward the target implantation site. Example 39. The method of any example herein, further comprising after inserting the second implant catheter, aspirating fluid and / or air out of a reservoir of the guide catheter through a flush port, the reservoir disposed distally to the seal stack. Example 40. The method of any example herein, wherein the first implant catheter is a docking device delivery apparatus and the prosthetic medical device is a docking device, and wherein the second implant catheter is a prosthetic heart valve delivery apparatus configured to deliver a prosthetic heart valve within the implanted docking device. Example 41. A seal housing assembly for a delivery apparatus, the seal housing assembly comprising: a housing; a fluid seal disposed within the housing; a spacer disposed within the housing proximally to the fluid seal; and a cross-slit valve disposed within the housing proximally to the fluid seal; wherein the fluid seal has a distal surface, having a circular shape, and a proximal surface, having a circular shape, disposed opposite to the distal surface; and wherein the fluid seal defines a slit extending from the first surface to the second surface through centers of the first and second surfaces. Example 42. The seal housing assembly of any example herein, wherein the cross- slit valve comprises a distal portion having a first outer diameter equal to or less than an inner diameter of the spacer, the distal portion of the cross-slit valve is received within the spacer, and a distal surface of the distal portion of the cross-slit valve fits snugly against the proximal surface of the fluid seal. Attorney Docket No: THVMC-23646WO01 Example 43. The seal housing assembly of any example herein, wherein a proximal end of the cross-slit valve comprises a frustoconical inner surface configured to direct a catheter being inserted through the seal housing assembly toward a center of the cross-slit valve. Example 44. The seal housing assembly of any example herein, wherein the fluid seal comprises at least one of: a polyisoprene material; polyisoprene rubber; elastomeric silicone; liquid silicone rubber; or high consistency rubber. Example 45. The seal housing assembly of any example herein, wherein the fluid seal has a Shore hardness in a range from 25 A to 50 A. Example 46. The seal housing assembly of any example herein, wherein the fluid seal has a Shore hardness in a range from 40 A to 50 A. Example 47. The seal housing assembly of any example herein, wherein the slit is configured to prevent entry of fluid through the fluid seal. The features described herein with regard to any example may be combined with other features described in any one or more of the other examples, unless otherwise stated. For example, any one or more of the features of one guide catheter may be combined with any one or more features of another guide catheter. As another example, any one or more features of one delivery apparatus may be combined with any one or more features of another delivery apparatus. In view of the many possible ways in which the principles of the disclosure may be applied, it should be recognized that the illustrated configurations depict examples of the disclosed technology and should not be taken as limiting the scope of the disclosure nor the claims. Rather, the scope of the claimed subject matter is defined by the following claims and their equivalents.

Claims

Attorney Docket No: THVMC-23646WO01 CLAIMS What is claimed is:

1. A delivery apparatus comprising: a seal housing assembly comprising a seal housing and a seal stack disposed within the seal housing; wherein the seal stack comprises a fluid seal having a first surface, having a circular shape, and a second surface, having a circular shape, disposed opposite to the first surface; and wherein the fluid seal defines a slit extending from the first surface to the second surface through centers of the first and second surfaces.

2. The delivery apparatus of claim 1, wherein the seal stack further comprises a spacer disposed proximately to the fluid seal and in contact with the first surface of the fluid seal or the second surface of the fluid seal.

3. The delivery apparatus of claim 1 or 2, wherein the seal stack further comprises a cross-slit valve, wherein at least a portion of the cross-slit valve is disposed proximately to the spacer and in contact with the spacer.

4. The delivery apparatus of any one of claims 1-3, wherein the fluid seal comprises a polyisoprene material.

5. The delivery apparatus of any one of claims 1-4, wherein the fluid seal comprises polyisoprene rubber.

6. The delivery apparatus of any one of claims 1-5, wherein the fluid seal is cylindrical.

7. The delivery apparatus of any preceding claim, further comprising: a handle comprising:Attorney Docket No: THVMC-23646WO01 a proximal segment comprising the seal housing assembly, the seal stack configured to allow insertion of a device into the handle and prevent fluid flow past the seal stack; an intermediate segment disposed adjacent and distal to the proximal segment, the intermediate segment including an inner surface defining a first lumen, wherein the first lumen has a first inner diameter, wherein the first lumen includes an inlet and an outlet; and a distal segment disposed adjacent and distal to the intermediate segment; and a shaft extending distally from the handle, the shaft including a distal end, a proximal end, and a second lumen extending between the distal end and the proximal end of the shaft, wherein the proximal end of the shaft is disposed within the distal segment of the handle and is coupled to the outlet of the first lumen, wherein the second lumen includes a second inner diameter that is less than the first inner diameter of the first lumen.

8. The delivery apparatus of claim 7, wherein the first lumen and the second lumen are coaxial.

9. The delivery apparatus of any one of claims 7-8, wherein the inner surface includes a band having a constant inner diameter equal to the first inner diameter.

10. The delivery apparatus of claim 9, wherein the band extends from the inlet of the first lumen to the outlet of the first lumen.

11. The delivery apparatus of any one of claims 7-8, wherein the inner surface includes a band, the band includes a distal end and a proximal end, and the inner surface is tapered from the distal end of the band to the outlet of the first lumen.

12. The delivery apparatus of claim 11, wherein the inner surface includes a step disposed between the inlet of the first lumen and the proximal end of the band.

13. A delivery apparatus comprising: a handle comprising:Attorney Docket No: THVMC-23646WO01 a proximal segment comprising a seal housing assembly comprising a seal housing and a seal stack disposed within the seal housing, the seal stack configured to allow insertion of a device into the handle and prevent fluid flow past the seal stack; an intermediate segment disposed adjacent and distal to the proximal segment, the intermediate segment including an inner surface defining a first lumen; and a distal segment disposed adjacent and distal to the intermediate segment; and a shaft extending distally from the handle, the shaft including a distal end, a proximal end, and a second lumen extending between the distal end and the proximal end of the shaft, wherein the proximal end of the shaft is disposed within the distal segment of the handle and is coupled to the first lumen; wherein the seal stack comprises a fluid seal having a distal surface, having a circular shape, and a proximal surface, having a circular shape, disposed opposite to the distal surface; and wherein the fluid seal defines a slit extending from the distal surface to the proximal surface through centers of the distal and proximal surfaces.

14. The delivery apparatus of claim 13, wherein the seal stack further comprises a spacer disposed proximately to the fluid seal and in contact with the proximal surface of the fluid seal.

15. The delivery apparatus of claim 13 or 14, wherein the seal stack further comprises a cross-slit valve, wherein at least a portion of the cross-slit valve is disposed proximately to the spacer and in contact with the spacer.

16. The delivery apparatus of any one of claims 13-15, wherein the intermediate segment comprises a reservoir including a reservoir lumen and at least a portion of the reservoir has a first diameter that is greater than a second diameter of the second lumen.Attorney Docket No: THVMC-23646WO01 17. The delivery apparatus of claim 16 wherein the intermediate segment further comprises a flush lumen in fluid communication with the reservoir lumen, the delivery apparatus further comprising a flush port fluidly coupled to the flush lumen.

18. The delivery apparatus of claim 16 or 17 wherein the reservoir lumen includes at least one of a cylindrical portion or a frustoconical portion.

19. A seal housing assembly for a delivery apparatus, the seal housing assembly comprising: a housing; a fluid seal disposed within the housing; a spacer disposed within the housing proximally to the fluid seal; and a cross-slit valve disposed within the housing proximally to the fluid seal; wherein the fluid seal has a distal surface, having a circular shape, and a proximal surface, having a circular shape, disposed opposite to the distal surface; and wherein the fluid seal defines a slit extending from the first surface to the second surface through centers of the first and second surfaces.

20. The seal housing assembly of claim 19, wherein the cross-slit valve comprises a distal portion having a first outer diameter equal to or less than an inner diameter of the spacer, the distal portion of the cross-slit valve is received within the spacer, and a distal surface of the distal portion of the cross-slit valve fits snugly against the proximal surface of the fluid seal.

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