Patent Description:
Prosthetic cardiac valves have been used for many years to treat various cardiac valvular disorders. For many years, the definitive treatment was the surgical repair or replacement of a native valve during open heart surgery. More recently, transvascular techniques have been developed, which reduce or eliminate many of the undesirable complications of open heart surgery. Such transvascular techniques traditionally involve the implantation of a prosthetic valve that can be compressed or folded to a reduced diameter. By compressing or folding the prosthetic valve to a reduced diameter, the prosthetic valve can be delivered through a less invasive penetration to a desired target location within the human anatomy. Thereafter, the compressed valve is traditionally released, expanded, separated from the delivery system, and secured to the desired target location. Exemplary prosthetic valves are known from <CIT>, <CIT>, <CIT> and <CIT>.

A valve prosthesis is provided which is suitable for implantation in body channels or ducts. The valve prosthesis includes an implantable structure having a deployable construction adapted to be initially crimped in a narrow configuration suitable for catheterization through the body ducts to a target location and adapted to be deployed by exerting substantially radial forces (or releasing the valve, if the valve is self-expandable) from within by means of a deployment device to a deployed state at the target location.

The valve prosthesis desirably includes a two-part foldable frame. The frame is configured to support the flexible leaflets of a unidirectional valve in an optimal manner. The frame has an "upper part" and a "lower part" wherein each part of the frame is shaped with rounded arc portions to support the leaflets. The leaflets are sandwiched between the upper and lower arcs. The frame can have portions, e.g., leaflet receiving portions, that are scalloped shaped to match the shape of the flexible leaflets.

The length of the arcs is matched to the total length of the cell struts that create the frame. The geometrical constraint on the length of the cell struts is such that the frame can be evenly crimped.

In one aspect of the invention, a cloth is first assembled (sewn) to the leaflets. The leaflets with the cloth are sandwiched between the two arcs and the cloth is wrapped over the arcs and sewn together. This suture line crosses all the fabric layers of the wrapped over cloth as well as the leaflet to create a robust leaflet attachment.

In one embodiment, an implantable prosthetic device is provided. The device comprises an upper frame section having a plurality of struts and a first leaflet receiving surface at a lower portion of the upper frame section, a lower frame section having a second leaflet receiving surface at an upper portion of the lower frame section, and at least one flexible leaflet with a first edge portion. The first edge portion is disposed between the first and second leaflet receiving surfaces. In specific implementations, the first and second leaflet receiving surfaces are scalloped shaped.

In other specific implementations, the device further comprises one or more cloth portions that are attached to the flexible leaflet at or near the first edge portion and wrapped around at least a portion of one or both of the first and second receiving surfaces to secure the flexible leaflet to the upper and lower frame sections. The cloth portions can be attached to the flexible leaflet so that a first excess cloth portion extends away from the first edge portion on an upper side of the flexible leaflet and a second excess cloth portion extends away from the first edge portion on a lower side of the flexible leaflet. The first and second excess cloth portions can be wrapped around the respective first and second leaflet receiving surface and secured to one another. In other specific implementations, the upper frame section and the lower frame section can be connected via one or more struts.

In other specific implementations, the upper and lower frame sections can be configured to be expanded from a first configuration to a second configuration. The lengths of the first and second leaflet receiving surfaces can be substantially the same in both the first and second configurations. In other specific implementations, the first leaflet receiving surface comprises an arc section. The arc section can be defined as a portion of the leaflet receiving surface that is located between one or more struts that extend away from the first leaflet receiving surface. The length of the arc section can be substantially equal to the combined length of one or more struts on the upper frame section.

In another embodiment, an implantable prosthetic device comprises a frame comprising a plurality of frame sections. Each frame section can have a lower portion with a scalloped shape. A flexible membrane can comprise a plurality of flexible leaflets, with each flexible leaflet having a lower portion with a scalloped shape. The lower portion of each flexible leaflet can be attached to the lower portion of each frame section.

In specific implementations, the lower portion of each frame section comprises a first part and a second part, the first and second parts being spaced apart to receive the lower portion of the flexible leaflets in an opening formed therebetween. In other specific implementations, one or more cloth portions are attached to each flexible leaflet, and the cloth portions are wrapped around at least a portion of the first and second parts to secure the flexible leaflets to the frame.

In other specific implementations, the frame further comprises first and second vertical posts at an upper area between two frame sections. The two vertical posts can be spaced apart so that they define an opening for receiving a first portion of a first flexible leaflet and a second portion of a second flexible leaflet. Both the first and second portions can be attached to a first and second cloth portion, respectively. The first and second cloth portions can be wrapped around at least a portion of the first and second vertical posts, respectively, to attach the flexible leaflets to the frame. In other specific implementations, a third cloth portion can be positioned radially outside of the frame. The first and second leaflets can be secured to the frame by attaching the first and second cloth portions to the third cloth portion.

In another embodiment, a method is provided for assembling an implantable prosthetic valve comprising a flexible membrane and crimpable frame with an upper and lower part. The method comprises partially crimping the frame to have a diameter that is less than the diameter of the frame when the valve is expanded to its functional size, positioning an edge of the flexible membrane between the upper and lower part of the frame, and securing the edge of the flexible membrane to both the upper and lower part of the frame.

In specific implementations, the method further comprises attaching a cloth portion to the edge of the flexible leaflet so that a first excess cloth portion extends away from the edge on an upper side of the flexible membrane and a second excess cloth portion extends away from the edge on a lower side of the flexible membrane. The first excess cloth portion can be wrapped around at least a portion of the upper part of the frame and the second excess cloth portion can be wrapped around at least a portion of the lower part of the frame. The first and second excess cloth portions can be secured to each other at an area radially outside of the frame.

The following description is exemplary in nature and is not intended to limit the scope, applicability, or configuration of the invention in any way. Various changes to the described embodiment may be made in the function and arrangement of the elements described herein without departing from the scope of the invention.

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 electrically, electromagnetically, and/or physically (e.g., mechanically or chemically) coupled or linked and does not exclude the presence of intermediate elements between the coupled items.

As used herein, the "expanded" or "deployed" state of a valve assembly or frame refers to the state of the valve assembly/frame when radially expanded to its functional size. The "crimped", "compressed" or "folded" state of a valve assembly or frame refers to the state of the valve assembly/frame when radially compressed or collapsed to a diameter suitable for delivering the valve assembly through a patient's vasculature on a catheter or equivalent mechanism. A valve assembly/frame that is "partially crimped" or "partially compressed" has a diameter that is less than the diameter of the valve assembly/frame in the expanded state and greater than the diameter of the valve assembly/frame in the compressed state.

Although the operations of exemplary embodiments of the disclosed method may be described in a particular, sequential order for convenient presentation, it should be understood that disclosed embodiments can encompass an order of operations other than the particular, sequential order disclosed. Further, descriptions and disclosures provided in association with one particular embodiment are not limited to that embodiment, and may be applied to any embodiment disclosed.

Moreover, for the sake of simplicity, the attached figures may not show the various ways (readily discernable, based on this disclosure, by one of ordinary skill in the art) in which the disclosed system, method, and apparatus can be used in combination with other systems, methods, and apparatuses. Additionally, the description sometimes uses terms such as "produce" and "provide" to describe the disclosed method. These terms are high-level abstractions of the actual operations that can be performed. The actual operations that correspond to these terms can vary depending on the particular implementation and are, based on this disclosure, readily discernible by one of ordinary skill in the art.

<FIG> shows a perspective view of an implantable prosthetic valve <NUM> (hereinafter "valve <NUM>"), suitable for percutaneous deployment and configured to replace a diseased native valve in a patient. As discussed in more detail below, valve <NUM> can include a generally cylindrical support frame, such as a stent, which is compressible and/or foldable to a smaller delivery diameter, and a plurality of flexible leaflets releasably attached to the support element.

The valve <NUM> in the illustrated embodiment comprises a flexible membrane, or leaflet assembly, <NUM> mounted on an expandable, annular support stent, or frame, <NUM>. As discussed in more detail below, frame <NUM> can comprise one or more scalloped portions <NUM> to which the flexible membrane is attached.

Valve <NUM> is desirably adapted to be radially collapsed or compressed to facilitate navigation through the narrow passages of a patient's vasculature to the treatment site within the patient's body. After valve <NUM> reaches the treatment site (e.g., the aortic valve annulus), valve <NUM> can be expanded within the orifice. To achieve the radial compression of the valve <NUM>, frame <NUM> desirably comprises a collapsible and/or compressible support structure.

Flexible membrane <NUM> can be attached to frame <NUM> so that the flexible membrane <NUM> permits fluid flow through the valve <NUM> in one direction along a structural axis of the frame <NUM> and resists fluid flow in the opposite direction. In particular, the implantable structure supports flexible leaflets that allow a forward flow through the valve prosthesis and prevent a reverse flow as the flexible leaflets collapse inwardly to block the reverse flow. To provide for such fluid flow, flexible membrane <NUM> can comprise a collapsible pliant material formed as flexible leaflets <NUM> that are arranged to collapse in a tricuspid arrangement. Alternatively, the flexible membrane can be formed into other configurations, including, for example, a mono cusp or bicuspid configuration. Flexible leaflets <NUM> can comprise three pieces of pliant material that are connected to each other at seams (also referred to as commissure tabs) to form the flexible membrane.

The flexible membrane <NUM> can be made from biological matter, such as natural tissue, pericardial tissue (such as bovine, procine or equine pericardium), a harvested natural valve or other biological tissue. Alternatively, the valve member <NUM> can be made from biocompatible polymers or similar materials. Various flexible leaflet configurations and materials for constructing such leaflets are described in <CIT>, <CIT>, and <CIT>.

As discussed above, frame <NUM> can comprise, for example, stent that has a generally cylindrical framework that can be expanded at a treatment site to secure valve <NUM> within or adjacent to the defective valve annulus. Frame <NUM> can also provide stability to the valve <NUM> and prevent the valve <NUM> from migrating after it has been implanted. Frame <NUM> can be a self-expanding frame or it can be expandable by a balloon member or other mechanical means. Frame <NUM> can be made from any of various suitable expandable and/or elastic materials and is typically made of a metal, such as stainless steel, CoCr alloys, titanium, or other biocompatible metals. Frame <NUM> also can be made from self expandable shape memory alloys, such as nickel titanium (NiTi) shape memory alloys, as marketed, for example, under the trade name Nitinol.

<FIG> is a schematic illustration of a flexible membrane <NUM> coupled to a frame <NUM> that is mounted on an inflatable balloon <NUM> of a balloon catheter for delivery and deployment of valve <NUM>. Valve <NUM> can be initially crimped to a smaller radial profile on balloon <NUM> so that is presents a narrower cross-sectional profile to facilitate percutaneous delivery of the valve <NUM> to the treatment site. <FIG> illustrates the valve <NUM> being deployed in the aorta A at the aortic annulus <NUM> to replace a diseased or damaged native aortic valve. However, it should be understood that the prosthetic valves described herein can be implanted in other channels or orifices in the body using the same techniques as the one used for the implantation of the aortic valve prosthesis. Such an implantation may, for example, include the implantation of: valves in the veins (for instance a cardiac valve), valves in the esophagus and/or at the stomach, valves in the ureter and/or the vesica, valves in the biliary passages, valves in the lymphatic system, and valves in the intestines.

In one embodiment, a delivery catheter can advance valve <NUM> (mounted on balloon <NUM>) through an introducer sheath and into the vasculature of a patient. The delivery catheter can then be advanced over a guidewire to move valve <NUM> to a target location in a body duct, such as the aortic annulus <NUM> of aorta A (<FIG>). After the valve <NUM> is properly positioned at the treatment site, balloon <NUM> can be inflated to expand frame <NUM> radially to the desired size, securing valve <NUM> at the treatment site. It should be understood that valve <NUM> can also be deployed using a non-inflatable, mechanical embodiment of the delivery catheter or, alternatively, valve <NUM> can be a self-expanding valve.

In one embodiment, frame <NUM> can comprise one or more scalloped portions <NUM> at a lower portion of frame <NUM>. <FIG> illustrates, for convenience, a flattened schematic view of a frame <NUM> that comprises a plurality of frame sections <NUM>, <NUM>, <NUM>, which each have a respective scalloped portion <NUM> at a lower portion of frame <NUM>. Frame sections <NUM>, <NUM>, <NUM> can comprise a plurality of struts (or strut sections) <NUM>, <NUM>. Adjacent scalloped portions <NUM> can be connected together by struts <NUM>. Because the frame is shown in a flattened view, the two end strut sections <NUM> of <FIG> appear to be disconnected; however, the two end strut sections <NUM> are desirably connected to one another, in the same manner of the other strut sections <NUM> shown in <FIG>.

Referring again to <FIG>, if desired, an expansion restriction member <NUM> can be secured between two adjacent strut sections <NUM>. Expansion restriction member <NUM> can be, for example, a suture or thread that is secured to adjacent strut sections <NUM> to prevent the valve <NUM> from being over-expanded during deployment.

<FIG> illustrates a valve <NUM> with a frame <NUM> that has a plurality of scalloped portions <NUM>. Frame <NUM> comprises a collapsible frame with a flexible membrane <NUM> attached thereto. As noted above, strut sections <NUM> desirably extend from a portion of the scalloped frame to provide structural strength to the frame <NUM>. The number of strut sections <NUM> between adjacent scalloped portions <NUM> can vary. For example, <FIG> shows two strut sections <NUM> (forming one cell) between adjacent scalloped portions <NUM>, while <FIG> shows four strut sections <NUM> between adjacent scalloped portions <NUM> (arranged to form three cells between adjacent scalloped portions). Strut sections <NUM> can also extend radially outward from the frame <NUM>, as shown in <FIG>, to help anchor the valve <NUM> in the body and to help prevent migration or movement of the valve after it has been deployed within the body. Other portions of the frame <NUM> can also be configured to extend radially outward to help anchor the valve in place. For example, certain cell struts, such as cell struts <NUM> (<FIG>), can be configured to extend radially outwards from the frame <NUM> to provide additional valve anchoring means.

As best shown in <FIG>, a frame <NUM> can be comprised of a first or "upper" part <NUM> and a second or "lower" part <NUM>. First part <NUM> can include a plurality of struts or strut sections <NUM> and a first arc section <NUM>. Second part <NUM> includes a second arc section <NUM>. Both arc sections <NUM>, <NUM> desirably have an arc length <NUM> that is substantially the same. First part <NUM> and second part <NUM> are desirably separate elements that are not connected to each other by any strut members of the frame <NUM>. Accordingly, as shown in <FIG>, when first part <NUM> is positioned adjacent second part <NUM>, a gap (or opening) <NUM> is defined between the two parts. A flexible membrane <NUM> or portions thereof can be received into gap <NUM> to facilitate attachment of the flexible membrane <NUM> to the frame <NUM>. The two surfaces facing gap <NUM> include a first leaflet receiving surface (e.g., the lower surface of upper part <NUM>) and a second leaflet receiving surface (e.g., the upper surface of lower part <NUM>). If desired, the first part <NUM> and second part <NUM> can be connected via one or more connecting struts <NUM> (<FIG>) to provide additional structural strength to the frame <NUM>.

In one embodiment, the flexible leaflets <NUM> of the flexible membrane <NUM> can be received in the gap <NUM> and the first and second arc sections <NUM> and <NUM> can help secure the flexible leaflets to the frame <NUM> and/or provide a point of attachment. Referring to <FIG>, a cloth member <NUM> is desirably attached to a flexible leaflet <NUM>. <FIG> is a perspective view of a leaflet sub-assembly <NUM> in which one or more portions of cloth <NUM> are attached to selected portions of flexible leaflet <NUM>. Leaflet sub-assembly <NUM> can be formed by attaching cloth <NUM> to flexible leaflet <NUM> by sewing (suturing) or other suitable attachment means. The cloth <NUM> can be any fabric or other material made from any of various suitable biocompatible synthetic materials, such as woven polyester, polyethylene terephthalate (PET), or polytetrafluoroethylene (PTFE).

To attach cloth <NUM> to the leaflet <NUM>, a cloth portion <NUM> can be folded over a lower edge portion <NUM> (<FIG>) of leaflet <NUM>, and cloth <NUM> and leaflet <NUM> can be sewn together along a leaflet-cloth suture line <NUM> (hereinafter "suture line <NUM>"). In this manner, leaflet edge <NUM> is captured between two layers of cloth <NUM> to form a leaflet attachment portion <NUM> (<FIG>). Excess portions <NUM> of cloth <NUM> extend along both sides of flexible leaflet <NUM> away from suture line <NUM> and away from edge <NUM>. As described in more detail below, excess cloth portions <NUM> can be used to secure the flexible leaflets <NUM> to the frame <NUM>. If desired, a plurality of separate cloth portions <NUM> (as shown in <FIG>) can be attached to the leaflet <NUM>. In this manner, when the leaflet is secured to the frame between the first and second arc sections <NUM>, <NUM>, the separate cloth portions <NUM> can extend between the struts that extend from the first arc section <NUM>.

Referring now to <FIG>, a method of attaching leaflet sub-assembly <NUM> to frame <NUM> is described. <FIG> is a simplified cross-sectional view of a leaflet sub-assembly attached to a frame. In particular, leaflet sub-assembly <NUM> extends radially between and is "sandwiched" or otherwise captured between first arc section <NUM> (of the first part <NUM> of the frame) and second arc section <NUM> (of the second part <NUM> of the frame). As shown in <FIG>, leaflet sub-assembly <NUM> can be positioned between the two arc sections so that suture-line <NUM> is substantially captured between the two arcs. Additionally, an edge portion <NUM> comprised of two layers of cloth and a portion of the leaflet desirably extends radially outwards from between the first and second arc sections <NUM> and <NUM>.

As illustrated in <FIG>, excess cloth portions <NUM> of cloth <NUM> can be wrapped over and around first arc section <NUM> and second arc section <NUM>. In this embodiment, excess portions <NUM> of cloth <NUM> can be sewn together within an attachment area <NUM>. Attachment area <NUM> is desirably located outside of (e.g., radially external to) frame <NUM>. For example, a sandwiching suture line <NUM> can pass through the two ends of excess cloth portions <NUM> and also through the edge portion <NUM> that extends out from between first and second arc sections <NUM> and <NUM>. Thus, by securing the flexible leaflet to the cloth and then securing portions of the cloth to itself, the flexible leaflet <NUM> can be securely attached to the frame <NUM> without requiring additional sutures passing through the flexible leaflet <NUM>. If desired, leaflet <NUM> can be positioned so that suture line <NUM> passes through the excess cloth portions <NUM> and through the leaflet <NUM>.

Conventional frames typically require suturing the flexible membranes at the commisures directly to vertical posts. However, the suture line applies local stress and abrasion on the leaflet which may lead to early leaflet failure. Accordingly, this approach causes very high stresses on the commissures when the flexible leaflets move between open and closed positions.

<FIG> illustrate a method of attaching flexible leaflets to a frame without suturing the flexible valves directly to vertical posts. <FIG> illustrates an upper portion <NUM> of frame <NUM> where two leaflets come together in the valve (e.g., the commissure). At the commissure, first frame part <NUM> has a first vertical strut <NUM> and a second vertical strut <NUM>. First strut <NUM> and second strut <NUM> are spaced apart and define an opening <NUM> therebetween for receiving at least a portion of two adjacent flexible leaflets <NUM>.

<FIG> is a cross-section view taken along line 9B-9B in <FIG>, with flexible leaflets and cloth portions shown positioned between the first and second struts <NUM>, <NUM>. As shown in <FIG>, two flexible leaflets 106a and 106b can be inserted and captured between first and second struts <NUM> and <NUM>. Flexible leaflet 106a, 106b can be attached to a respective cloth <NUM>, creating an area <NUM> where the leaflet 106a is attached to the cloth <NUM> and an area where the leaflet 106a is not attached to the cloth <NUM>. Leaflet 106a can be wrapped around at least a portion of first strut <NUM> so that the unattached portion of the leaflet 106a extends radially inwards into the interior of the frame. The unattached portion of cloth <NUM> can form an excess cloth portion <NUM> that extends radially inward into the frame and wraps back around the strut <NUM>.

Similarly, leaflet 106b can be attached to a cloth <NUM>, creating an area <NUM> where the leaflet 106b is attached to the cloth <NUM> and an area where the leaflet 106b is not attached to the cloth <NUM>. Leaflet 106b can be wrapped around second strut <NUM> so that the unattached portion of the leaflet 106b extends radially inwards into the interior of the frame. The unattached portion of cloth <NUM> can form an excess cloth portion <NUM> that extends inward into the frame and wraps back around the strut <NUM>.

To secure the leaflets 106a, 106b to the frame, another piece of cloth <NUM> can be placed radially outside of the frame and positioned over the portion of flexible leaflets 106a, 106b that extend radially outside of the frame (e.g., the portions of <NUM>, <NUM> that are external to struts <NUM>, <NUM>). The second piece of cloth <NUM> can be sewn to the leaflet 106a at an attachment area <NUM> to secure the leaflets to first strut <NUM>. Thus, the second piece of cloth <NUM> can be sewn (or otherwise attached) to leaflet 106a, the portion of cloth <NUM> attached to leaflet 106a, and to the excess cloth portion <NUM> that has been wrapped around first strut <NUM>. The second piece of cloth <NUM> can similarly be sewn to the leaflet 106b, the portion of cloth <NUM> attached to leaflet 106b, and to the excess cloth portion <NUM> (which has been wrapped around second strut <NUM>) at an attachment area <NUM> to secure the leaflets to second strut <NUM>.

Operationally, when flexible leaflets <NUM> are closed, load F is applied to the leaflets to move them radially inward as shown in <FIG>. Folding flexible leaflets <NUM> around stent struts <NUM> and <NUM> can reduce stresses on the leaflets by creating a friction attachment at leaflet-strut contact areas <NUM>, which reduces the stresses at suture lines <NUM>. Furthermore, as discussed in more detail below, by securing the leaflets 106a, 106b at attachment areas <NUM>, <NUM> on the outer side of frame <NUM>, relative movement at the leaflet/frame interface can be reduced or eliminated, which further reduces stresses and strains on the leaflets during expansion and/or compression of the valve <NUM>.

<FIG> shows another embodiment by which flexible leaflets 106c, 106d can be attached to first and second struts <NUM> and <NUM> of a frame <NUM>. Similar to the embodiment shown in <FIG> and described above, a first leaflet 106c is secured to a cloth <NUM> by a suture <NUM> and an excess cloth portion <NUM> extends inwardly of the frame and wraps back around first strut <NUM> to extend back outwardly of the frame. A second leaflet 106d is secured to a cloth <NUM> by a suture <NUM> and an excess cloth portion <NUM> extends inwardly of the frame and wraps back around second strut <NUM> to extend back outwardly of the frame. After the excess portions of cloth <NUM>, <NUM> are wrapped back around first and second struts <NUM>, <NUM>, they can be secured to one another by another suture <NUM> at an area outside of the frame <NUM>. As shown in <FIG>, suture <NUM> can pass through both of the excess cloth portions <NUM>, <NUM> and through portions of the leaflets (e.g., leaflet portions <NUM>, <NUM>) that extend outward from between the first and second struts <NUM>, <NUM>. In addition, if desired, the excess cloth portions and/or flexible leaflets can be folded and/or wrapped around each other so that the suture <NUM> extends through one or more portions of the excess cloth portions and/or the flexible leaflets.

<FIG> show additional embodiments of frames <NUM> that have scalloped portions. In particular, <FIG> illustrate alternative shapes and configurations of struts <NUM>, <NUM>. The shape and number of struts can vary. For example, struts <NUM> can be configured to be substantially straight (<FIG>), or they can be rounded or curved (<FIG>).

As described above with regard to <FIG>, the struts or other frame members can also be configured to extend radially outward of the generally cylindrical surface of the expandable framework to improve the ability to anchor the frame to the tissue. For example, as best seen in <FIG>, <FIG>, struts <NUM> and/or <NUM> may be bent so that they protrude outward from stent struts <NUM> (i.e., radially outward from the tangential plane P defined on an external surface of the cylindrically shaped frame <NUM>). Similarly, in the embodiments illustrated in <FIG>, struts <NUM> and/or <NUM> can be formed so that one or more of struts <NUM> and/or <NUM> extend radially outward from the frame <NUM>.

The use of the scalloped frame <NUM> together with the methods of attachment described herein beneficially enable the flexible membrane and flexible leaflets to be secured to a frame without introducing needle holes and/or sutures in the area where a leaflet flexes (e.g., leaflet flexing area <NUM> shown in <FIG>) or undergoes significant stresses. Leaflets are particularly susceptible to failure at areas where they flex and by reducing and/or eliminating needle holes in the leaflets at these areas, the structural integrity of the flexible leaflets can be improved. Thus, in contrast to traditional methods of attachment where a flexible membrane is simply sutured to a frame, the methods of attachment described herein eliminate and/or reduce needle holes and sutures in the leaflet flexing area <NUM>, which increases the durability of the valve.

In addition, the leaflet can be attached to the frame along the length of the first and second arc sections <NUM> and <NUM>. By capturing the entire edge <NUM> (or substantially the entire edge) of flexible leaflet <NUM> between the arc sections <NUM> and <NUM> and securing the leaflet to the arc sections as described herein, the leaflet stresses can be optimally distributed along the length of the leaflet edge.

In addition, the methods described herein are particularly useful to facilitate attaching a flexible membrane to a frame while the valve is in a partially collapsed (partially-crimped) configuration. As described in <CIT>, the entire disclosure of which is incorporated by reference herein, it can be desirable to attach a flexible membrane to a partially collapsed frame, which can allow the frame to be constructed with relatively large angles between adjacent struts to enhance the structural rigidity of the frame. Due to the enhanced structural rigidity, the frame can be constructed with thinner metal struts, which can allow the frame to be crimped to a smaller profile. However, it can be difficult to attach a flexible membrane to a frame in a partially collapsed state because the diameter of the flexible membrane is greater than the diameter of the partially collapsed frame. For instance, in certain implementations, the diameter of the valve member can be twice that of the partially collapsed frame. The valve member therefore cannot easily conform to the shape of the partially collapsed frame, and as a result, assembly of the valve assembly is rendered more difficult.

The frames described herein can easily and accurately receive flexible membranes while the frames are in a partially collapsed configuration. In addition, by reducing the relative movement that occurs between the frame and the flexible leaflets during expansion of the valve at the treatment site, the valves produced by the methods describe herein have increased strength and durability.

Referring again to <FIG>, first and second arc sections <NUM> and <NUM> are substantially the same length (e.g., arc length <NUM>). The length of the first and second arc sections <NUM>, <NUM> desirably can be selected to correspond to the length of a similarly scalloped shaped edge portion of a leaflet. Thus, as described herein, the accurate assembly of the scalloped-shaped leaflet <NUM> between the two arc sections <NUM>, <NUM> can be achieved. In addition, the attachment of the leaflet <NUM> to the arc sections <NUM>, <NUM> can be easily and accurately performed even if the frame <NUM> is in a crimped (folded) or partially crimped configuration due to the fact that the arc length of sections <NUM>, <NUM> where the leaflet is attached remains constant when the frame is compressed.

<FIG> illustrate a segment of a frame that is configured to expand from a reduced profile (<FIG>) to an expanded profile (<FIG>) while maintaining the relationship between first and second arc sections <NUM>, <NUM>. In particular, the length of corresponding portions of first and second arc sections <NUM>, <NUM> are desirably matched to the lengths of related struts SL1, SL2, and SL3. For example, as shown in <FIG>, arc section <NUM> can be defined by the length of arc section <NUM> between two strut members extending therefrom (e.g., SL1 and SL3). Arc section <NUM> can be configured to have substantially the same length as the combined length of one or more struts. In particular, Arc section <NUM> is configured to be substantially the same length as the combined length of struts SL2 and SL3.

After flexible leaflets are attached to the frame, the frame can expand smoothly and evenly from a reduced profile (<FIG>) to an expanded profile (<FIG>), causing arc sections <NUM>, <NUM> to also expand evenly. This even expansion from a first profile to a second profile reduces relative movement between the arc sections, which, in turn, reduces stress on the leaflets that are attached to the arc sections. Moreover, because the length of the struts are matched to corresponding lengths of sections of the first and second arc sections <NUM>, <NUM>, relative movement between the frame and flexible leaflets is reduced in all configurations and stages of crimping and/or expansion. Thus, a flexible leaflet can be attached to the frame shown in <FIG> and then, if desired, the frame can be crimped (or folded) to an even smaller profile without causing additional stresses at the leaflet attachment area.

In prior art implantable valve devices, during deployment, the dimensions of the complete, implantable structure of the implantable valve vary from its initial first crimped position to its final deployed position. Thus, typically when attaching flexible leaflets to the implantable structure one should take into consideration the dimension changes and leave "slack" or extra leaflet material so that upon deployment of the valve device the flexible leaflets do not tear or deform. By maintaining a constant arc length of the arc sections during deployment of valve <NUM>, there is no need for "slack" material in the flexible leaflets <NUM>. Instead, the attachment points of the flexible leaflets <NUM> remain at a constant distance regardless of the delivery position of valve <NUM> (crimped or expanded).

Referring to <FIG>, another embodiment of a frame <NUM> is disclosed. <FIG> shows a section of a compressed frame that comprises first arc section <NUM> and second arc section <NUM>, with the two arc sections being connected via optional connecting struts <NUM>. As described above with regard to <FIG>, relative movement between the first and second arc sections <NUM>, <NUM> can be avoided by matching arc sections with strut sections so that the first arc section <NUM> and second arc section <NUM> remain constant during deployment, providing a stable area for anchoring flexible leaflets <NUM>. As shown in <FIG>, in this embodiment, the arc length of arc section <NUM> is matched to the total length SL of cell struts SL1, SL2, and SL3. That is, the total length SL (SL1 + SL2 + SL3) of the strut sections is substantially the same as the length of arc section <NUM>. Because the geometrical constraint on length SL of cell struts <NUM> is designed such that cell struts <NUM> may be collapsed and expanded without changing the dimensions of the first and second arc sections <NUM> and <NUM>, the frame <NUM> can be evenly crimped and/or expanded, which allows flexible leaflets <NUM> to also deploy evenly.

In embodiments disclosed above, little or no relative movement exists between the flexible leaflets <NUM> and attachment points on the first and second arc sections <NUM> and <NUM>. As a result, the valve has greater durability and is capable of withstanding the harsh conditions prevailing within the vasculature and especially the millions of cycles of stress applied by the blood pressure.

Claim 1:
An implantable prosthetic valve (<NUM>), comprising
a radially collapsible and expandable annular frame (<NUM>), said frame (<NUM>) having an outflow end and an inflow end and a row of cells formed by struts (<NUM>, <NUM>) at the outflow end, wherein
at an upper area between two frame sections (<NUM>, <NUM>, <NUM>) of the frame (<NUM>), the frame (<NUM>) comprises a pair of vertical posts (<NUM>, <NUM>) defining an opening (<NUM>) therebetween for supporting commissures of a leaflet assembly (<NUM>), the upper area being located at the outflow end of the frame (<NUM>), and
wherein the pair of vertical posts (<NUM>, <NUM>) is positioned axially along the frame (<NUM>) entirely within the row of cells formed by struts (<NUM>, <NUM>) at the outflow end;
a leaflet assembly (<NUM>) positioned within the frame (<NUM>) and configured to permit fluid flow through the implantable prosthetic valve (<NUM>) in one direction along a structural axis of the frame (<NUM>) and resist fluid flow in the opposite direction.