Patent Description:
Some applications of the present invention relate in general to the application of heat-transfer fluid to work-pieces during their preparation. More specifically, some applications of the present invention relate to the cooling of a Nitinol frame of a prosthetic heart valve or <NUM> vascular stent during crimping.

The use of shape memory alloys (SMAs) has been widely adopted in a range of medical devices. SMAs possess shape memory as a result of the alloy undergoing a reversible temperature-dependent transformation between an austenite molecular structure and a martensite molecular structure. Thus, SMA-based medical devices may possess shape memory in that they can be reformed from an original, austenitic configuration to a second, martensitic configuration by lowering their temperature, and subsequently restored to their original austenitic configuration, by elevating their temperature. Importantly, when an SMA device, in its original shape and size, is cooled to its martensitic state, and subsequently deformed, it will retain its deformed shape and size. Upon warming of the SMA device to its austenitic state, the device will recover its original shape and size.

The use of SMAs has been shown to be particularly useful in the context of implants percutaneously implanted into a patient's cardiovascular system, including prosthetic heart valves. Due to the relatively narrow diameter of the vascular system via which prosthetic heart valves are frequently delivered, it is often desirable to deliver the implant in a crimped state, achieved while the implant is in its martensitic configuration. When the implant is exposed to physiological temperatures, the implant undergoes transformation to its austenitic configuration. The thermoelastic expansion enabled by the implant's transformation to its austenitic configuration may be controlled mechanically by housing the implant within a sleeve of a delivery tool. The regulated release of the implant from the housing enables the gradual return of the implant to its original shape and size upon delivery to the desired anatomical location.

<CIT> discloses apparatus for crimping a frame of an implant, the apparatus comprising: a crimping device comprising (i) a base, and (ii) a crimping mechanism that defines a crimping aperture; wherein: the crimping aperture has an open state and a narrowed state, the crimping device further comprises a handle, the crimping mechanism being actuatable by moving the handle circumferentially around the crimping mechanism, and actuation of the crimping mechanism transitions the crimping aperture from its open state to its narrowed state;the apparatus further comprising a bath (i) having a floor, (ii) defining a receptacle that is shaped to receive a portion of the crimping device, and (iii) having one or more side-walls, the one or more side-walls: extending upward from the floor to a side-wall height, and including a port-defining side-wall, wherein the port-defining side-wall defines a port between outside of the bath and inside of the bath; the apparatus having an assembled state in which: the portion of the crimping device has been received by the receptacle, the crimping device is held securely by the bath, the aperture is below the side-wall height, and the port is aligned with the crimping aperture.

<CIT> discloses systems and devices for crimping a medical device and associated methods. A crimping device is disclosed which can include, for example, a frame including a stationary plate, a movable member, and a plurality of blades arranged to form a channel and each including a pin that projects through a slot on the movable member and a corresponding slot on the stationary plate. The crimping device can be actuated to move the movable member relative to the stationary plate to drive the pins along paths defined by the slots to thereby drive the blades radially inward to crimp a medical device positioned within the channel. SUMMARY OF THE INVENTION.

The present invention is directed to an apparatus according to claim <NUM> for temperature control during crimping of a medical implant.

When an SMA device, in its original shape and size, is cooled to its martensitic state, and subsequently deformed, it will retain its deformed shape and size. Upon warming of the SMA device to its austenitic state, the device will recover its original shape and size. Since implants comprising SMAs, such as nickel titanium (Nitinol), are more easily deformed while in their martensitic state, it is therefore desirable to crimp such an implant while cooled below its transition temperature. Such crimping of a cooled SMA implant reduces a likelihood of damaging the implant or delivery tool during the crimping and loading processes.

The present teaching relates to apparatus for crimping a frame of an SMA implant while the SMA implant is at least partially submerged in a cooled liquid that maintains the SMA implant in its martensitic state. The submersion of the frame of an SMA implant during crimping is achieved by disposition of a crimping device within a bath of the cooled liquid.

Features of the present teaching include alignment of the crimping aperture with a port in a side-wall of the bath, enabling advancing a delivery tool that comprises a shaft and a housing at a distal end of the shaft, housing-first, through the port, at least until the housing reaches the aperture, crimping the frame onto the delivery tool by actuating the crimping mechanism.

The present invention includes a seal configured to maintain sealing as the housing and the shaft pass through the port during the advancing.

In an application, threading the frame onto the part of the delivery tool includes threading the frame onto the part of the delivery tool subsequently to inserting the part of the delivery tool through the port into the bath.

Reference is made to <FIG>, which are schematic illustrations of a crimping assembly <NUM>, comprising a crimping device <NUM> and a bath <NUM>, in accordance with some applications of the invention.

Crimping device <NUM> comprises a base <NUM>, and a crimping mechanism <NUM> that defines a crimping aperture <NUM> having an open state shown in <FIG>, <FIG> & <FIG>, as well as a narrowed state shown in <FIG> and <FIG>. Bath <NUM> has a floor <NUM>, and one or more side-walls <NUM> extending upward from the floor to a side-wall height D34. Typically, side-wall height D34 is the height to which bath <NUM> is fillable with a liquid, e.g., the lowest height of the one or more side-walls. Bath <NUM> defines a receptacle <NUM> that is shaped to receive a portion of crimping device <NUM>, such that the crimping device is held securely by the bath <NUM>.

<FIG> show crimping assembly <NUM> in its assembled state, in which crimping device <NUM> is disposed within bath <NUM>, and is held securely by the bath. In the assembled state, the aperture <NUM> is below side-wall height D34. Typically, and as shown, the receptacle <NUM> is a recess in floor <NUM> of bath <NUM>, and the recess is shaped to snugly receive base <NUM> of crimping device <NUM>.

Typically, and as shown, bath <NUM> includes a port-defining side-wall <NUM>, which defines a port <NUM> that defines a channel <NUM> between outside of the bath and inside of the bath. Typically, in the assembled state port <NUM> is aligned with crimping aperture <NUM>. For example, a height D35 of the aperture may be within <NUM> of a height D33 of the port. Alternatively or additionally, port <NUM> may be disposed in a rotational position of the aperture that is within <NUM> degrees of a rotational position of the port <NUM>. This alignment typically places channel <NUM> and aperture <NUM> along a co-linear axis <NUM> (<FIG>).

For some applications, crimping assembly <NUM> comprises two or more separable components, which undergo assembly prior to use. For example, bath <NUM> and crimping device <NUM> may be provided as separate components, which are assembled prior to use, e.g., by the operator or by a technician. For such applications, assembly <NUM> is typically assembled by introducing a portion of the crimping device (e.g., base <NUM>) into receptacle <NUM> (<FIG>).

Typically, and as shown, bath <NUM> is shaped to receive crimping device <NUM> in a pre-defined rotational orientation of the crimping device with respect to the bath, and receptacle <NUM> and the portion of the crimping device (e.g., base <NUM>) are cooperatively shaped to inhibit, in the assembled state, rotation of the crimping device <NUM> from the pre-defined rotational orientation. For example, and as shown, receptacle <NUM> may define a protrusion <NUM>, and device <NUM> (e.g., base <NUM> thereof) may be shaped to define a notch <NUM> (or vice versa), the protrusion being disposed within the notch.

For example, complementary couplings such as catches and/or locks may be used.

For other applications, crimping assembly <NUM> may be provided pre-assembled, with crimping device <NUM> already secured within bath <NUM>. For some such applications, device <NUM> does not comprise a distinct base <NUM>. Aside from these differences, the pre-assembled crimping assembly is typically as described hereinabove.

Reference is now also made to <FIG>, which are schematic illustrations of crimping assembly <NUM>, in accordance with some applications of the invention. Crimping mechanism <NUM> has a working radius D80 from the center of aperture <NUM> to the end of handle <NUM>. For some applications, during the operation of crimping mechanism <NUM>, handle <NUM> revolves about halfway circumferentially around mechanism <NUM> (i.e., with respect to aperture <NUM>). Therefore, crimping mechanism <NUM> defines a working diameter D82, defined as twice working radius D80.

Bath <NUM> has an internal width D84, measured at height D33, typically transverse to axis <NUM>. Typically, and as shown in <FIG>, internal width D84 is greater than working diameter D82. Typically, D84 is less than <NUM> greater than D82, (e.g., less than <NUM> greater, less than <NUM> greater, e.g., <NUM>-<NUM> greater).

Crimping mechanism <NUM> has a thickness D88. Thickness D88 is typically <NUM>-<NUM> (e.g., <NUM>-<NUM>). Typically, and as shown in <FIG>, bath <NUM> has another internal width D86, measured at height D33, measured along axis <NUM>. For some applications, width D86 is sufficiently great that an operator may place a hand on each side of crimping mechanism <NUM> in order to load the implant onto the tool. Therefore, for some applications, width D86 is greater than thickness D88 plus <NUM>-<NUM> (e.g., <NUM>-<NUM>) on each side of crimping mechanism <NUM>. Internal widths D84 and D88 are both typically <NUM>-<NUM> (e.g., <NUM>-<NUM>). For some applications, and as shown, bath <NUM> is generally circular, and diameters D84 and D88 are generally equal to each other (e.g., within <NUM> percent of each other, such as identical to each other).

Reference is made to <FIG>, which are schematic illustrations showing crimping assembly <NUM> being used in combination with a delivery tool <NUM> to crimp a frame <NUM> of an implant <NUM>, in accordance with some applications of the invention. As shown, implant <NUM> (<FIG>) may comprise a prosthetic heart valve, to be implanted at a native heart valve of a subject. Frame <NUM> is typically a shape-memory alloy such as nickel titanium (Nitinol). When an SMA device, in its original shape and size, is cooled to its martensitic state, and subsequently deformed, it will retain its deformed shape and size. Upon warming of the SMA device to its austenitic state, the device will return to its original shape and size.

As depicted in <FIG>, the co-linear axis <NUM> of port <NUM> and crimping aperture <NUM> enables advancement of a delivery tool <NUM> (<FIG>), which as depicted may include a shaft <NUM> and housing <NUM>, through port <NUM>, at least until housing <NUM> reaches aperture <NUM>. Port <NUM> typically comprises an external portion <NUM> that is outside the bath. In certain embodiments, port <NUM> defines channel <NUM> having an internal diameter of <NUM>-<NUM> (e.g., <NUM>-<NUM> or <NUM>-<NUM>), and comprises a seal <NUM> that reversibly closes the channel (detailed in <FIG>) configured to maintain sealing as housing <NUM> and shaft <NUM> pass through channel <NUM> during the advancing.

The presence of a cooled liquid <NUM> within bath <NUM> maintains frame <NUM> at a cool temperature during crimping of the frame. Liquid <NUM> typically has a temperature of between - <NUM> and <NUM> degrees C (e.g., <NUM>-<NUM> degrees C). In some applications of the invention, a portion <NUM> of liquid <NUM> may be frozen. For example, as well as putting liquid <NUM> into bath <NUM>, frozen liquid (e.g., saline ice) 60a may also be added, in order to maintain liquid <NUM> at its cool temperature throughout the duration of the crimping of frame <NUM>.

<FIG> shows assembly <NUM> prior to introduction of tool <NUM> or implant <NUM>. <FIG> shows liquid <NUM> having been introduced into bath <NUM> prior to insertion of tool <NUM>, but the liquid may alternatively be introduced after insertion of the tool. <FIG> and <FIG> depict advancement of tool <NUM> into crimping aperture <NUM>, such that frame <NUM> is disposed within the crimping aperture and immersed within cooled liquid <NUM>. Frame <NUM> may be allowed to cool for a period of time while immersed in cooled liquid <NUM>, prior to crimping. This period of time may typically last greater than <NUM> seconds (e.g., greater than <NUM> seconds) and/or less than <NUM> minutes (e.g., between <NUM> seconds and <NUM> minutes, such as <NUM>-<NUM> minutes). <FIG> shows contraction of crimping aperture <NUM> upon frame <NUM>, crimping frame <NUM> while immersed in cooled liquid <NUM>. Since implants comprising SMAs such as Nitinol are more easily deformed while in their martensitic state, it is therefore desirable to crimp such an implant while cooled below its transition temperature. Cooling of an SMA implant during crimping, which reduces a likelihood of damaging the implant or delivery tool during the crimping and loading processes, is achieved by disposition of crimping device <NUM> within a bath of the cooled liquid as shown in <FIG> and <FIG>. <FIG> shows retraction of tool <NUM> through channel <NUM> of port <NUM>, with implant <NUM> disposed within housing <NUM>. Enlarged inset of <FIG> shows passage of tool shaft <NUM> through seal <NUM>, while the seal prevents leakage of cooled liquid <NUM>.

It is likely that some of liquid <NUM> becomes introduced into the subject during implantation of implant <NUM>. Therefore, liquid <NUM> is typically suitable for introduction into the subject, e.g., being sterile, non-toxic, and/or isotonic. For example, liquid <NUM> may be sterile saline. It is to be noted that the crimping of implant <NUM> while immersed in cooled liquid <NUM>, as described above, may reduce or obviate the need for subsequent flushing of air from the implant.

It is to be noted that the "heights" described herein (e.g., side-wall height D34, port-height D33, and aperture-height D35) are all heights above the same reference point, e.g., floor <NUM>.

Reference is made to <FIG>, <FIG>, and <FIG>, which are schematic illustrations showing the sealing of port <NUM> during advancing of housing <NUM> and shaft <NUM> of delivery tool <NUM> through the port. Some embodiments of the device include one or more washers <NUM>, <NUM>, and <NUM> fitted a first sealing nut <NUM> and a second sealing nut <NUM> (<FIG>). Port <NUM> may be secured to port-defining side-wall <NUM> using screws (e.g., as shown), an adhesive, and/or any other suitable securing means.

Delivery tool housing <NUM> is advanced through a cap <NUM> (i.e., through an opening defined in the cap) (<FIG>). Subsequently, housing <NUM> is advanced through port <NUM> (<FIG>). Optionally, a plurality of plugs <NUM> are subsequently arranged into a ring that circumscribes shaft <NUM> and is disposed in an annular gap <NUM> between the shaft and external portion <NUM> of port <NUM> (<FIG>).

Subsequently, cap <NUM> is fastened to external portion <NUM> of port <NUM> (<FIG>). For example, for some applications, an interior portion of cap <NUM> may be shaped to define threading, and cap <NUM> may be secured to port <NUM> by being screwed onto the port. Using cap <NUM> and plugs <NUM> in this manner allows port <NUM> to be configured to facilitate advancement of tool <NUM> through the port with relatively low resistance, and for sealing of the port <NUM> to be subsequently increased using the cap and plugs.

For some applications, the screwing of cap <NUM> onto external portion <NUM> pushes plugs <NUM> into gap <NUM>.

Claim 1:
Apparatus (<NUM>) for crimping a frame of an implant (<NUM>), the apparatus comprising:
a crimping device (<NUM>) comprising (i) a base (<NUM>), and (ii) a crimping mechanism (<NUM>) that defines a crimping aperture (<NUM>); wherein:
the crimping aperture has an open state and a narrowed state,
the crimping device further comprises a handle (<NUM>), the crimping mechanism being actuatable by moving the handle circumferentially around the crimping mechanism, and
actuation of the crimping mechanism transitions the crimping aperture from its open state to its narrowed state;
the apparatus further comprising a bath (<NUM>) (i) having a floor (<NUM>), (ii) defining a receptacle (<NUM>) that is shaped to receive a portion of the crimping device, and (iii) having one or more side-walls (<NUM>), the one or more side-walls:
extending upward from the floor to a side-wall height (D34), and
including a port-defining side-wall (<NUM>), wherein the port-defining side-wall defines a port (<NUM>) between outside of the bath and inside of the bath;
the apparatus having an assembled state in which:
the portion of the crimping device has been received by the receptacle,
the crimping device is held securely by the bath,
the aperture is below the side-wall height, and
the port is aligned with the crimping aperture;
characterized in that the port defines a channel (<NUM>) and comprises a seal (<NUM>) that reversibly closes the channel.