Patent Description:
The present application is directed to an active introducer sheath system for use with catheter-based technologies for repairing and/or replacing heart valves, as well as for delivering an implant, such as a prosthetic valve to a heart via the patient's vasculature.

Endovascular delivery catheter assemblies are used to implant prosthetic devices, such as prosthetic valves, at locations inside the body that are not readily accessible by surgery or where access without invasive surgery is desirable. For example, aortic, mitral, tricuspid, and/or pulmonary prosthetic valves can be delivered to a treatment site using minimally invasive surgical or transcatheter techniques.

An introducer system can be used to safely introduce a delivery apparatus into a patient's vasculature (e.g., the femoral artery). An introducer system generally has an elongated introducer sheath that is inserted into the vasculature and a handle that contains one or more sealing valves that allow a delivery apparatus to be placed in fluid communication with the vasculature with minimal blood loss. Once the introducer sheath is positioned within the vasculature, the shaft of the delivery apparatus is advanced through the sheath and into the vasculature, carrying the prosthetic device. Introducer systems can be used in the delivery of prosthetic devices in the form of implantable heart valves, such as balloon-expandable implantable heart valves. An example of such an implantable heart valve is described in <CIT> entitled "Valve Prosthesis for Implantation in the Body and a Catheter for Implanting such Valve Prosthesis," and also in <CIT> entitled "Prosthetic Heart Valve". The introducer systems can also be used with the delivery systems for other types of implantable devices, such as self-expanding and mechanically-expanding implantable heart valves, stents or filters.

Conventional methods of accessing a vessel, such as a femoral artery, prior to introducing the delivery apparatus include dilating the vessel using multiple dilators or sheaths that progressively increase in diameter. This repeated insertion and vessel dilation can increase the amount of time the procedure takes, as well as the risk of damage to the vessel. Expandable introducer sheaths, formed of highly elastomeric materials, allow for the dilating of the vessel to be performed by the passing prosthetic device. <CIT>, entitled "Expandable Sheath for Introducing an Endovascular Delivery Device into a Body", discloses a sheath with a split outer polymeric tubular layer and an inner polymeric layer. A portion of the inner polymeric layer extends through a gap created by the cut and can be compressed between the portions of the outer polymeric tubular layer. Upon expansion of the sheath, portions of the outer polymeric tubular layer separate from one another, and the inner polymeric layer is expanded to a substantially cylindrical tube. Advantageously, the sheath disclosed in the '<NUM> patent can locally and temporarily expand for passage of implantable devices and then return to its starting diameter. This expansion is passive in nature, in that it is not directly controlled by the practitioner performing the procedure. The passive expansion occurs due to the pressure that the passing implantable device places on the inner surfaces of the sheath.

<CIT> (US'<NUM>) provides for devices and methods for providing endovascular therapy, including facilitating establishment of vascular access, placement of endovascular sheaths, catheter tip localization, and administration of vascular occlusion. US'<NUM> describes a vessel cannulation device, an expandable sheath, an occlusion catheter, and a localizer each of which may be provided separately or used as part of a system. US'<NUM> provides a vessel cannulation device including: a housing having a distal end with a distal tip and a proximal end; a guidewire lumen passing through the housing and at least the distal tip; a sensor coupled to the guidewire lumen; and an advancing member, which is configured for advancing at least one of a guidewire or a sheath and which is operably coupled to the sensor.

There remains a need for further improvements in expandable introducer sheaths for endovascular systems used for implanting valves and other prosthetic devices.

The claimed invention is defined in independent claim <NUM> and relates to an active introducer sheath system. Some preferred configurations of the claimed invention are defined in dependent claims <NUM> to <NUM>. Also described herein are related aspects, examples, embodiments and arrangements useful for understanding the claimed invention, and which do not necessarily constitute embodiments of the claimed invention. The subject-matter for which protection is sought is defined by the claims.

The active introducer sheath systems disclosed herein allow a practitioner to actively initiate the expansion of the sheath at any time during the procedure, separate from the passing of the delivery system. The sheath is expanded by activating a translation mechanism at the handle of the introducer sheath system. The sheath has an inner cylindrical structure of comingled fixed and mobile elongate rods bound together by an attachment line, such as an attachment wire, that extends around the rods. Proximal portions of the fixed rods are fixedly attached to the handle, whereas proximal portions of the mobile rods are attached to the translation mechanism of the handle. Activating the translation mechanism causes the mobile rods to move axially with respect to the fixed rods, changing the internal tension in the attachment wire. Increased tension draws the fixed and mobile rods closer together, decreasing the diameter of the cylindrical structure. On the other hand, relaxing the tension in the attachment wire enables the fixed and mobile rods to move apart, increasing the diameter of the cylindrical structure. This active expansion mechanism allows the practitioner to precisely control the outer diameter during both expansion and contraction of the sheath.

The active introducer sheath systems can also include an outer cover extending around the inner cylindrical structure. The outer cover can be formed of, or include, an elastomeric or a non-elastomeric material.

In some embodiments, each fixed rod of the inner cylindrical structure is positioned adjacent to a mobile rod. The inner cylindrical structure can include, for example, <NUM>, <NUM>, <NUM>, <NUM>, or <NUM> elongate fixed rods. The elongate mobile rods and the elongate fixed rods can be formed of, or can include, metal materials or polymer materials.

The elongate rods are bound together by one or more attachment lines that extend around the rods. The attachment line or lines can be, for example, metal wires or polymer bands. In some embodiments, the attachment lines can include at least one flat outer surface to assist with bending. The attachment lines can be structured as a plurality of rings, where each ring connects the elongate rods of the inner cylindrical structure. Alternatively, one or more attachment lines can form a coil to connect the elongate rods of the inner cylindrical structure. For example, the attachment lines can be threaded through the elongate rods, or they can be attached to outer surfaces of the elongate rods. In either case, the attachment of the elongate rod to an attachment line forms a connection point. The attachment line can be welded, crimped, or bonded to an elongate rod at a given connection point. In some embodiments, the attachment line or lines can also be attached to the outer cover.

The translation mechanism of the handle can include a screw mechanism. For example, the screw mechanism can include a rotating nut that is attached to the set of mobile rods and threaded around the handle such that it is axially movable along the handle. In some embodiments, each elongate mobile rod is attached at its proximal end to a sliding ring which encircles the handle and engages the rotating nut, for example, via an interlocking connection feature extends circumferentially around the handle. The sliding ring, which is positioned distally to the rotating nut, translates axial movement from the rotation of the nut to the mobile rods.

Methods of moving prosthetic devices through an active introducer sheath system, for example, to deliver a prosthetic heart valve to a patient, are also disclosed herein to facilitate understanding of the claimed invention. When performing a minimally invasive procedure, the active introducer sheath system is inserted into a patient, for example, into the femoral artery, prior to activating the translation mechanism to initiate sheath expansion. Activating the translation mechanism can be performed, in some embodiments, by rotating a screw mechanism, which pushes or pulls the set of elongate mobile rods axially with respect to the set of elongate fixed rods. The movement of the mobile rods with respect to the fixed rods lowers an internal tension in the attachment lines of the inner cylindrical structure, allowing the inner cylindrical structure to expand in diameter. The prosthetic device can then be pushed through the expanded inner cylindrical structure. The inner cylindrical structure can be contracted after pushing the prosthetic device through by moving the set of mobile rods in a reverse direction via the translation mechanism. In some embodiments of the method, the inner cylindrical structure expands to the extent that its inner diameter is wider than the greatest outer diameter of the passing prosthetic device. Upon contraction, the outer diameter of the inner cylindrical structure can be returned to an original outer diameter.

The subject-matter for which protection is sought is defined by the appended claims. The following description of certain examples should not be used to limit the scope of these claims. Other examples, features, aspects, embodiments, and advantages will become apparent to those skilled in the art from the following description. As will be realized, the device and/or methods are capable of other different and obvious aspects, all without departing from the scope of the appended claims.

For purposes of this description, certain aspects, advantages, and novel features of the embodiments of this disclosure are described herein. The described methods, systems, and apparatus should not be construed as limiting in any way. Instead, the present disclosure is directed toward all novel and nonobvious features and aspects of the various disclosed embodiments, alone and in various combinations and sub-combinations with one another. The disclosed methods, systems, and apparatus are not limited to any specific aspect, feature, or combination thereof, nor do the disclosed methods, systems, and apparatus require that any one or more specific advantages be present or problems be solved.

Features, integers, characteristics, compounds, chemical moieties, or groups described in conjunction with a particular aspect, embodiment or example are to be understood to be applicable to any other aspect, embodiment or example described herein unless incompatible therewith. All of the features disclosed in this specification (including any accompanying claims, abstract, and drawings), and/or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive. The claimed invention is defined by the appended claims and therefore not restricted to the details of any foregoing embodiments.

As used in the specification and the appended claims, the singular forms "a," "an" and "the" include plural referents unless the context clearly dictates otherwise.

Throughout the description and claims of this specification, the word "comprise" and variations of the word, such as "comprising" and "comprises," means "including but not limited to," and is not intended to exclude, for example, other additives, components, integers or steps. "Exemplary" means "an example of" and is not intended to convey an indication of a preferred or ideal aspect. "Such as" is not used in a restrictive sense, but for explanatory purposes.

The terms "proximal" and "distal" as used herein refer to regions of a sheath, catheter, or delivery assembly. "Proximal" means that region closest to handle of the device, while "distal" means that region farthest away from the handle of the device.

"Axially" or "axial" as used herein refers to a direction along the longitudinal axis of the sheath.

The disclosed active introducer sheath systems minimize trauma to the blood vessel during the delivery of a prosthetic device. During a transcatheter procedure, insertion and expansion of the introducer sheath causes the vessel walls to stretch radially, while insertion of the prosthetic device through the introducer causes the vessel walls to stretch longitudinally. When a passing prosthetic device stretches the sheath, the vessel walls are stretched in both directions simultaneously, which can lead to tearing. Disclosed embodiments of the active introducer sheath systems allow a practitioner to actively initiate the expansion of the sheath at any time during the procedure, separate from the passing of the delivery system. Tearing risk is minimized because longitudinal stretching occurs separately from radial stretching. The sheath is expanded by activating a translation mechanism at the handle of the introducer sheath system. The sheath has an inner cylindrical structure of comingled fixed and mobile elongate rods bound together by an attachment line, such as an attachment wire, that extends around the rods. Proximal portions of the fixed rods are attached to the handle, whereas proximal portions of the mobile rods are attached to the translation mechanism of the handle. Activating the translation mechanism causes the mobile rods to move axially with respect to the fixed rods, changing the internal tension in the attachment wire. Increased tension draws the fixed and mobile rods closer together, decreasing the diameter of the cylindrical structure. On the other hand, relaxing the tension in the attachment wire enables the fixed and mobile rods to move apart, increasing the diameter of the cylindrical structure. This active expansion mechanism allows for precise control over the outer diameter during both expansion and contraction of the sheath. Push force, or the force it takes to advance the prosthetic device through the sheath, is minimized because the prosthetic device itself is not responsible for expanding the sheath, further reducing potential trauma to the vessel walls.

<FIG> illustrates the proximal end of an active introducer sheath system <NUM> according to the present disclosure. The introducer sheath system <NUM> is configured for use with a delivery apparatus <NUM> to deliver a prosthetic implant, such as a prosthetic heart valve, to a patient. For example, the shaft <NUM> of the representative delivery apparatus <NUM> shown in <FIG> can be inserted through the handle <NUM> and sheath <NUM> of introducer sheath system <NUM> to deliver a prosthetic device to a patient. It should be understood that the delivery apparatus <NUM> described herein is exemplary only, and that other similar delivery systems can of course be used with the introducer sheath system <NUM>.

As outlined above, the sheath <NUM> includes an inner cylindrical structure <NUM> of comingled fixed and mobile elongate rods bound together by an attachment line that extends around the rods. An outer cover <NUM> extends around the inner cylindrical structure <NUM> comprising the mobile rods. In <FIG>, only the outer cover <NUM> of the sheath <NUM> is visible. The outer cover <NUM> can be formed of an elastomeric material, such as silicone or urethane, for example. An elastomeric outer cover <NUM> will stretch to conform to the expansion state of the underlying inner cylindrical structure <NUM>. Alternatively, the outer cover <NUM> can be formed of a non-elastomeric material, such as dyneema membrane, polyether ether ketone (PEEK), or polyethylene terephthalate (PET). A non-elastomeric outer cover <NUM> has excess material that will wrinkle or fold when the underlying inner cylindrical structure <NUM> is in a contracted state.

In some embodiments, the sheath <NUM> has an inner diameter of about <NUM> millimeters (<NUM> French) when contracted, and an inner diameter of about <NUM> millimeters (<NUM> French) when expanded. In some embodiments, the sheath <NUM> has an outer diameter of about <NUM> millimeters (<NUM> French) when contracted and about <NUM> millimeters (<NUM> French) when expanded. In some embodiments, the wall thickness of the sheath <NUM> is from about <NUM> to about <NUM> millimeters when contracted, and from about <NUM> to about <NUM> millimeters when expanded. However, the dimensions of the sheath can vary. The numerical values given above to describe a sheath embodiment are not meant to limit the scope of the disclosure.

The introducer sheath system <NUM> has a central lumen extending through its handle <NUM> and sheath <NUM>. At a proximal end of the central lumen, the introducer sheath system <NUM> includes a hemostasis valve that prevents leakage of pressurized blood. Generally, during use a distal end of the sheath <NUM> is passed through the skin of the patient and inserted into a vessel, such as the femoral artery. The shaft <NUM> of a delivery apparatus <NUM>, such as the one shown in <FIG>, is then inserted into the introducer sheath system <NUM> through the proximal hemostasis valve, and advanced through the patient's vasculature to deliver the prosthetic device to the patient. Flush tubing <NUM> is attached to the introducer sheath system <NUM>, and is used to fill the system with saline or another physiologically balanced solution prior to advancing the sheath <NUM> into the patient, ensuring no air bubbles are introduced to the bloodstream.

The representative delivery apparatus <NUM> shown in <FIG> includes a steerable guide catheter <NUM>, which includes a handle portion <NUM> coupled to an elongated shaft <NUM>. A balloon catheter <NUM> extends through the handle portion <NUM> and the shaft <NUM> of the guide catheter <NUM>, and is in fluid communication with balloon <NUM>. The guide catheter <NUM> and the balloon catheter <NUM> illustrated in <FIG> are adapted to slide longitudinally relative to each other to facilitate delivery and positioning of a prosthetic heart valve at an implantation site in a patient's body. In <FIG>, balloon <NUM> is depicted in an inflated state, but it is understood that balloon <NUM> is deflated during advancement through the introducer sheath system <NUM> and the patient's vasculature. A prosthetic heart valve or other prosthetic device can be crimped onto balloon <NUM> for delivery to the procedure site. The delivery apparatus <NUM> also includes flush tubing <NUM> to prevent air bubbles from entering the bloodstream.

<FIG> is a perspective view of the inner cylindrical structure <NUM> of sheath <NUM> in its expanded state. Proximal portions of three cylindrically arranged fixed rods <NUM> are fixedly attached at handle <NUM>, which is not shown in <FIG>. Proximal portions of three mobile rods <NUM> are attached, either directly or indirectly, to the translation mechanism of the handle <NUM>, which will be described in more detail below (in reference to <FIG> and <FIG>). The mobile and fixed rods <NUM>, <NUM> are comingled, such that each fixed rod <NUM> is adjacent a mobile rod <NUM>. One or more attachment lines <NUM> extend through the comingled mobile and fixed rods <NUM>, <NUM>, binding the rods together and maintaining the cylindrical shape along the length of the sheath <NUM>.

Upon activation of the translation mechanism <NUM> at handle <NUM> (<FIG>), the mobile rods move axially in the direction of the arrows shown in <FIG>. Because of the stationary position of the fixed rods <NUM>, the movement of the mobile rods <NUM> increases the internal tension in the attachment line <NUM>, which draws the mobile and fixed rods <NUM>, <NUM> closer together, changing their radial locations and decreasing the diameter of the inner cylindrical structure <NUM>, as shown in <FIG>. The cross-sectional diagram of <FIG> shows the inner cylindrical structure <NUM> in its expanded state, whereas <FIG> shows the inner cylindrical structure <NUM> in its contracted state. The distance between adjacent mobile and fixed elongate rods <NUM>, <NUM> decreases as the overall diameter of the inner cylindrical structure decreases. <FIG> show a side view of an expanded and collapsed inner cylindrical structure <NUM>, respectively. The attachment angle, α, made at connection points <NUM> between the attachment line <NUM> and the longitudinal axis of an elongate rod, decreases as the mobile rods <NUM> are translated axially with respect to the fixed rods <NUM>. The expansion rate of sheath <NUM> changes as the attachment angle α gets larger or smaller.

The elongate mobile and fixed rods <NUM>, <NUM> can be formed of polymer materials or from metal materials such as, for example, stainless steel, nitinol, or cobalt-chromium. The number of rods can be varied to alter the expansion rate of sheath <NUM>. While the embodiments depicted in <FIG> show a total of six elongate rods, it is understood that the inner cylindrical structure <NUM> can have as few as four total rods (two mobile and two fixed) or as many as twelve total rods (six mobile and six fixed). The elongate mobile and fixed rods <NUM>, <NUM> may be cylindrical, as depicted in <FIG>, or they may be rectangular/linear for increased rigidity. In some embodiments, the elongate rods <NUM>, <NUM> can be from about <NUM> to about <NUM> millimeters thick in a direction perpendicular to their longitudinal axis. This size range provides structural rigidity while minimizing the wall thickness of the inner cylindrical structure <NUM>. However, the rods may be other thicknesses without deviating from the scope of the disclosure.

The attachment line <NUM> is depicted in <FIG> as being threaded through the elongate rods <NUM>, <NUM>. Alternatively, the attachment line <NUM> could extend around the outside or inside of elongate rods <NUM>, <NUM>. The attachment line <NUM> attaches to each elongate rod at a series of connection points <NUM>. The attachment line <NUM> can be welded to each rod, crimped to each rod, or bonded to each rod using a bonding agent, such as a glue or other adhesive compound. In some embodiments, the attachment line <NUM> can be attached by different methods at different connection points <NUM>. The attachment line <NUM> can be structured as a series of discrete rings that connect the mobile and fixed rods <NUM>, <NUM>. For example, as shown in <FIG>, each ring extends around or through each mobile rod <NUM> and each fixed rod <NUM> at connection points <NUM>. Alternatively, part or all of the attachment line <NUM> can be structured as a continuous coil that connects each mobile rod <NUM> and each fixed rod <NUM>, e.g., by winding around or through the mobile and fixed rods <NUM>, <NUM>. Some embodiments may have a flat attachment line <NUM>, meaning an attachment line that includes at least one flat outer surface, which can facilitate bending to ease the radial expansion.

The thickness and rigidity of the attachment line <NUM> are balanced to provide substantial strength to the inner cylindrical structure <NUM> while maximizing the mobility of the mobile rods <NUM> with respect to fixed rods <NUM>. The attachment line <NUM> can be formed, for example, by metal wires or polymer bands. Exemplary materials that can be used to form the attachment line or lines <NUM> include highly elastic metals, such as (but not limited) to nitinol and spring metals such as spring stainless steel, or highly elastic polymers, such as (but not limited to) monofilament PEEK, a liquid crystal polymer, or PET. In some embodiments, the attachment line <NUM> can range in thickness from about <NUM> millimeters to about <NUM> millimeters. However, the attachment line can be other thicknesses without deviating from the scope of the disclosure.

The outer cover <NUM>, shown in <FIG>, can be attached to the underlying inner cylindrical structure <NUM> by a variety of methods, including but not limited to laminating, gluing, melting, or sewing. The outer cover <NUM> can be attached to the fixed rods <NUM> of the inner cylindrical structure <NUM>. In some embodiments, the outer cover <NUM> can be attached to the connection points <NUM> between the fixed rods <NUM> and the attachment line <NUM>.

<FIG> depicts the connection of the inner cylindrical structure <NUM> to the handle <NUM> of an active introducer sheath system <NUM>. The introducer sheath system <NUM> is shown in a partially collapsed configuration. A partially collapsed configuration can be used to limit contact between elongate rods <NUM>, <NUM> and inner tubing <NUM>, thereby reducing the friction encountered by a passing prosthetic device. Sheath <NUM> is depicted without an outer cover <NUM> to better visualize the workings of the inner cylindrical structure <NUM>. The elongate rods <NUM>, <NUM> of the inner cylindrical structure <NUM> are arranged cylindrically around an inner tubing <NUM> at the base <NUM> of the sheath <NUM>, as shown in <FIG>. When the sheath <NUM> is collapsed or partially collapsed, the elongate rods <NUM>, <NUM> taper inward toward the inner tubing <NUM> because their proximal portions are embedded within the handle <NUM>. The smallest collapsed diameter of sheath <NUM> is therefore realized at a location more distal than is shown in <FIG> and <FIG>. The radial location of elongate rods <NUM>, <NUM> within the handle can be varied, such that the rods are fixed closer or farther from inner tubing <NUM> as needed for a particular application. During a procedure, the elongate rods <NUM>, <NUM> and inner tubing <NUM> enter the body, while base <NUM> and handle <NUM> remains outside of the body. As such, the structure and dimensions of the handle <NUM> can be altered to suit a particular application. <FIG> and <FIG> are described as one exemplary embodiment.

The base <NUM> shown in <FIG> comprises notches <NUM> to permit the elongate mobile rods <NUM> to move in a radial direction, which occurs when the tension in the attachment line <NUM> draws them closer to the fixed rods <NUM>. In the embodiment depicted in <FIG>, the handle <NUM> is encircled by a screw type translation mechanism <NUM> that includes a rotating nut <NUM> and a distal sliding ring <NUM>.

<FIG> shows a longitudinal cross section of the handle <NUM> and translation mechanism <NUM> shown in <FIG>. Handle <NUM> comprises a central lumen <NUM>, through which the shaft <NUM> and prosthetic device of a delivery apparatus <NUM> can be passed. Central lumen <NUM> is sized to receive and enable the passage of the prosthetic device through to inner tubing <NUM>. The inner tubing <NUM> of sheath <NUM>, which extends distally from the central lumen <NUM> of the handle <NUM>, is made of a highly elastomeric material to guide and permit the passage of the delivery apparatus shaft carrying the prosthetic device. For example, in some embodiments, the inner tubing <NUM> can be formed of polyurethane. An inner tubing <NUM> formed of polyurethane can stretch to a diameter up to <NUM>% greater than its original diameter to facilitate the passage of the prosthetic device. Alternatively, the inner tubing <NUM> of sheath <NUM> can be made of a non-elastic material that wrinkles when in the collapsed state.

Elongate fixed rods <NUM> are embedded in the distal portion of handle <NUM>. In some embodiments, connector pieces <NUM> help to secure the proximal ends of the elongate fixed rods <NUM> within the handle <NUM>. In the depicted embodiment, the proximal portions of elongate mobile rods <NUM> are embedded within the distal sliding ring <NUM> of the translation mechanism <NUM>. Connector pieces <NUM> can be used to secure the proximal ends of the elongate mobile rods <NUM> to the translation mechanism <NUM>. Rotating nut <NUM> is threadably engaged to handle <NUM>, such that it can be axially translated along the handle upon rotation. The rotating nut <NUM> is attached to the elongate mobile rods <NUM> via the distal sliding ring <NUM>, such that rotation of the nut <NUM> moves the elongate mobile rods <NUM> in an axial direction. The distal sliding ring <NUM> depicted in <FIG> has traveled a portion of the length of notch <NUM> to partially collapse sheath <NUM>. As the distal sliding ring <NUM> continues to travel within notch <NUM>, distal regions of sheath <NUM> will continue to narrow in diameter as the tension between the mobile elongate rods <NUM> and the fixed elongate rods <NUM> increases.

In the embodiment depicted, the rotating nut <NUM> and the sliding ring <NUM> are engaged by a circumferentially extending interlocking connection feature <NUM>. The interlocking connection feature <NUM> includes a ridge extending from the rotating nut <NUM> and engaging a slot on distal ring <NUM>. However, other embodiments could include alternative mechanisms to attach distal sliding ring <NUM> to rotating nut <NUM>. Other translation mechanisms are also possible, including but not limited to other screw-type mechanisms, or hydraulic mechanisms, or slider mechanisms. The translation mechanism can be configured to expand the inner cylindrical structure by pulling the elongate mobile rods <NUM> or by pushing the elongate mobile rods <NUM>.

In an alternative embodiment, elongate rods <NUM>, <NUM> can be embedded within walls of sheath <NUM>, i.e. between the outer cover <NUM> and an inner layer that replaces the inner tubing <NUM> shown in <FIG>. In this embodiment, the fixed elongate rods <NUM> can be attached at various points along their length to the outer cover <NUM> and to the inner layer, whereas the mobile elongate rods <NUM> and the attachment line <NUM> are free to move to enable expansion and collapse of the sheath <NUM> as described above.

Methods of delivering a prosthetic device to a patient via an active introducer sheath system are also disclosed herein. The methods include moving the prosthetic device through the introducer sheath system <NUM> and into a patient's vasculature. Generally, during use, the sheath <NUM> shown in <FIG> is passed through the skin of patient (usually over a guidewire) such that the distal end region of the sheath <NUM> is inserted into a vessel, such as a femoral artery, and then advanced to a wider vessel, such as the abdominal aorta. The translation mechanism <NUM> at the handle <NUM> is then activated, pushing or pulling the set of elongate mobile rods <NUM> axially with respect to the elongate fixed rods <NUM> and lowering an internal tension in the attachment line <NUM>. This release of the internal tension in attachment line <NUM> enables the inner cylindrical structure <NUM> to expand in diameter. In some implementations, the inner diameter of the inner cylindrical structure <NUM> is expanded to a wider diameter than the greatest outer diameter of the prosthetic device, minimizing the frictional push force encountered when delivering the prosthetic device. The delivery apparatus shaft <NUM> shown in <FIG> and the prosthetic device are then inserted through the central lumen <NUM> of the handle <NUM>. The prosthetic device on shaft <NUM> is pushed through stretchable inner tubing <NUM> and advanced through the patient's vasculature until the prosthetic device is delivered to the implantation site and implanted within the patient.

Once the prosthetic device has passed the sheath <NUM> on its way to the implantation site, the sheath <NUM> can be contracted, or reduced in diameter, to reduce forces on the blood vessel walls during the implantation procedure. To contract the inner cylindrical structure, the translation mechanism moves the elongate mobile rods <NUM> in the reverse direction, thereby increasing the tension in attachment line <NUM>. Advantageously, the outer diameter of the inner cylindrical structure <NUM> can be decreased back to its original outer diameter (the outer diameter prior to passage of the prosthetic device). Once the implantation procedure is complete, the active sheath <NUM> can again be expanded to retrieve the delivery apparatus <NUM>. Advantageously, the diameter of the active sheath <NUM> is precisely controlled by the practitioner, and can be widened and contracted to accommodate any situations that arise during the procedure.

As described above, the active introducer system <NUM> and delivery apparatus <NUM> can be used to deliver, remove, repair, and/or replace a prosthetic device. In one example, a heart valve (in a crimped or compressed state) can be placed on the distal end portion of an elongated delivery apparatus shaft <NUM> and inserted into the sheath <NUM>. Next, the shaft <NUM> and heart valve can be advanced through the patient's vasculature to the treatment site, where the valve is implanted.

Beyond transcatheter heart valves, the active introducer sheath system <NUM> can be useful for other types of minimally invasive surgery, such as any surgery requiring introduction of an apparatus into a subject's vessel. For example, the active introducer sheath system <NUM> can be used to introduce other types of delivery apparatus for placing various types of intraluminal devices (e.g., stents, stented grafts, balloon catheters for angioplasty procedures, etc.) into many types of vascular and non-vascular body lumens (e.g., veins, arteries, esophagus, ducts of the biliary tree, intestine, urethra, fallopian tube, other endocrine or exocrine ducts, etc.).

Claim 1:
An active introducer sheath system (<NUM>) comprising:
a handle (<NUM>) comprising a translation mechanism (<NUM>),
a sheath (<NUM>) comprising an inner cylindrical structure (<NUM>), wherein the inner cylindrical structure (<NUM>) comprises:
a set of elongate fixed rods (<NUM>) arranged cylindrically, wherein each fixed rod (<NUM>) comprises a proximal portion that is fixedly attached to the handle (<NUM>), and
a set of elongate mobile rods (<NUM>) arranged cylindrically and comingled with the set of fixed rods (<NUM>), wherein each mobile rod (<NUM>) comprises a proximal portion that is attached to the translation mechanism (<NUM>), such that activation of the translation mechanism (<NUM>) causes the set of mobile rods (<NUM>) to move axially with respect to the fixed rods (<NUM>); and,
one or more attachment lines (<NUM>) connecting the comingled fixed (<NUM>) and mobile rods (<NUM>);
wherein movement of the set of elongate mobile rods (<NUM>) with respect to the set of elongate fixed rods (<NUM>) alters the internal tension of the attachment line (<NUM>), shifting the radial location of each fixed rod (<NUM>) and each mobile rod (<NUM>), thereby changing the diameter of the inner cylindrical structure (<NUM>) from a first diameter to a second diameter.