Adjustable length patent foramen ovale (PFO) occluder and catch system

Devices, delivery systems and techniques for an occlusion device for the closure of physical anomalies, such as an atrial septal defect, a patent foramen ovale (PFO), and other septal and vascular defects are described. The devices, delivery systems and techniques relate to, but are not limited to, a patent foramen ovale (PFO) occluder made from a substantially cylindrical form. An occluder having a distal side and a proximal side, with a catch system for securing the deployed configuration, is introduced into the treatment site by a delivery sheath. In one aspect, the occluder has an adjustable length center joint that allows the device to fit a particular septal defect. In some embodiments, the occluder includes a catch member that holds the occluder in the deployed, expanded profile configuration. In one aspect, the catch member also has an adjustable length.

FIELD OF THE INVENTION

This invention relates generally to occlusion devices for the closure of physical anomalies, such as an atrial septal defect, a patent foramen ovale (PFO), and other septal and vascular defects. In particular, the invention relates to occlusion devices with an adjustable length center joint. The invention also relates to catch systems and delivery systems and techniques for such devices.

BACKGROUND OF THE INVENTION

A patent foramen ovale (PFO), illustrated inFIG. 1, is a persistent, one-way, usually flap-like opening in the wall between the right atrium11and left atrium13of the heart10. Because left atrial (LA) pressure is normally higher than right atrial (RA) pressure, the flap usually stays closed. Under certain conditions, however, right atrial pressure can exceed left atrial pressure, creating the possibility that blood could pass from the right atrium11to the left atrium13and blood clots could enter the systemic circulation. It is desirable that this circumstance be eliminated.

The foramen ovale serves a desired purpose when a fetus is gestating. Because blood is oxygenated through the umbilical cord, and not through the developing lungs, the circulatory system of the fetal heart allows the blood to flow through the foramen ovale as a physiologic conduit for right-to-left shunting. After birth, with the establishment of pulmonary circulation, the increased left atrial blood flow and pressure results in functional closure of the foramen ovale. This functional closure is subsequently followed by anatomical closure of the two overlapping layers of tissue: septum primum14and septum secundum16. However, a PFO has been shown to persist in a number of adults.

The presence of a PFO is generally considered to have no therapeutic consequence in otherwise healthy adults. Paradoxical embolism via a PFO is considered in the diagnosis for patients who have suffered a stroke or transient ischemic attack (TIA) in the presence of a PFO and without another identified cause of ischemic stroke. While there is currently no definitive proof of a cause-effect relationship, many studies have confirmed a strong association between the presence of a PFO and the risk for paradoxical embolism or stroke. In addition, there is significant evidence that patients with a PFO who have had a cerebral vascular event are at increased risk for future, recurrent cerebrovascular events. The presence of a PFO has also recently been linked to chronic migraines. While the reasons are still under investigation, PFO closure has been shown to eliminate or significantly reduce chronic migraine headaches in many patients.

Accordingly, patients at such an increased risk are considered for prophylactic medical therapy to reduce the risk of a recurrent embolic event. These patients are commonly treated with oral anticoagulants, which potentially have adverse side effects, such as hemorrhaging, hematoma, and interactions with a variety of other drugs. The use of these drugs can alter a person's recovery and necessitate adjustments in a person's daily living pattern.

In certain cases, such as when anticoagulation is contraindicated, surgery may be necessary or desirable to close a PFO. The surgery would typically include suturing a PFO closed by attaching septum secundum to septum primum. This sutured attachment can be accomplished using either an interrupted or a continuous stitch and is a common way a surgeon shuts a PFO under direct visualization.

Umbrella devices and a variety of other similar mechanical closure devices, developed initially for percutaneous closure of atrial septal defects (ASDs), have been used in some instances to close PFOs. These devices potentially allow patients to avoid the side effects often associated with anticoagulation therapies and the risks of invasive surgery. However, umbrella devices and the like that are designed for ASDs are not optimally suited for use as PFO closure devices.

Currently available septal closure devices present drawbacks, including technically complex implantation procedures. Additionally, there are significant complications due to thrombus, fractures of the components, conduction system disturbances, perforations of heart tissue, and residual leaks. Many devices have high septal profile and include large masses of foreign material, which may lead to unfavorable body adaptation of a device. Given that ASD devices are designed to occlude holes, many lack anatomic conformability to the flap-like anatomy of PFOs. Thus, when inserting an ASD device to close a PFO, the narrow opening and the thin flap may form impediments to proper deployment. Even if an occlusive seal is formed, the device may be deployed in the heart on an angle, leaving some components insecurely seated against the septum and, thereby, risking thrombus formation due to hemodynamic disturbances. Finally, some septal closure devices are complex to manufacture, which may result in inconsistent product performance.

Various devices and delivery systems have been developed to deliver occluders and other medical devices through body lumens. Some delivery systems of the prior art are used to deliver devices that readily expand to a delivered configuration when removed from the delivery system. Other occluders do not readily expand into a deployed configuration and techniques are used to change the configuration of the device into the deployed configuration. In the latter case, once an occluder is delivered to the desired delivery site and deployed, the occluder must have a catch system that keeps the device in the deployed configuration.

The devices and techniques disclosed herein are designed to address these and other deficiencies of prior art septal closure devices and techniques for delivering and retrieving such devices.

SUMMARY OF THE INVENTION

Aspects of the invention relate to implants including an occluder and a catch system for the occluder, as well as devices and techniques for delivering an implant into a desired location within the body and securing the implant in the deployed configuration. In certain embodiments, the implants include, but are not limited to, a septal occluder made from a polymer tube or a tubular form defined by filaments having delivery and deployment configurations. These delivery techniques, in addition to use with septal occluders, could be applied to other medical devices, such as other expandable devices constructed from an underlying tubular structure.

Certain embodiments of the present invention further include a catch system for securing an occluder in a deployed configuration. In some embodiments, the catch system includes a catch member, preferably disposed in an axially central portion of a septal occluder. Catch members are constructed and arranged to apply force of desired magnitude and orientation to designated portions of the occluder device to maintain the occluder at its implant location. In preferred embodiments, the catch member is adjustable along at least its axial length, enabling occluder implantation in and closure of PFO's having a variety of dimensions.

Aspects of the present invention relate to devices and techniques for making the center joint of the occluder expandable so that an occluder can accommodate different thicknesses of septal tissue. In one embodiment, a helical cut is provided in the center joint and it expands as needed in the desired delivery location. An expandable catch member may be used in this configuration also.

In another embodiment of the invention, the center joint is constructed of coil, braid or zig-zag construction. In still another embodiment, the center joint may be a telescoping system.

According to at least some embodiments, the occluder is substantially tubular or cylindrical. According to some embodiments, the tube includes a material selected from the group consisting of metals, shape memory materials, alloys, polymers, bioabsorbable polymers, and combinations thereof. In particular embodiments, the tube includes a shape memory polymer. In particular embodiments, the tube includes nitinol. In some embodiments, the tube is formed by rolling a flat piece of material into a tubular form. According to some embodiments, the device is formed by cutting the tube. In other embodiments, the occluder is formed by aligning and selectively bonding a plurality of filaments in a substantially cylindrical shape. The occluder is placed in its deployment configuration by reducing the axial length of the device.

In another aspect, the present invention provides a catch system that includes a catch member that has an adjustable catch distance, and provides the appropriate compression of the septa for closure purposes. A catch member according to one embodiment is formed of an elastic material that extends beyond a proximal opening of the occluder.

In another embodiment, the catch member is a helical spring that can stretch axially. In some embodiments, the proximal end of the catch member forms a spiral that has a diameter larger than a central passage of the occluder so that the occluder is prevented from collapsing into its delivery configuration. A recess can be provided in the passage so that the spiral is at least partially disposed in the recess. This may reduce the material exposed at the end of the device and help prevent thrombus formation.

In another embodiment of the invention, the catch member may be made from a resilient material that can be stretched. The material can be solid or tubular. The proximal end has a “T” shaped end that can extend across the diameter of the central passage of the occluder.

In another embodiment of the invention, a collapsible medical device for occluding an aperture in a body is provided. The medical device has a first configuration with a reduced profile and a second configuration with an expanded profile and is adapted to be delivered through a delivery system into a desired delivery location. The medical device has a proximal side and a distal side and an occluder portion movable between a first and a second configuration. The occluder portion includes an axial passage along the length of the collapsible medical device. The medical device further includes a catch system for holding the occluder portion in the second configuration, including a catch member adapted to be disposed in the passage such that the occluder can move from the first configuration to the second configuration. The catch member includes a catch body and a catch element at its proximal end that has a dimension that is larger than a diameter of the axial passage at the proximal end of the occluder portion and a catch length provided by the catch body is adjustable to correspond to a length of the aperture.

In another embodiment of the invention, the catch member is made of polymeric material including at least one of bioabsorbable polymeric material, shape-memory polymeric material and a biocompatible metal material.

In another embodiment of the invention, the catch element is configured to seat in a recess at the proximal end of the axial passage of the occluder portion.

In yet another embodiment of the invention, the catch element includes a flange or stick or coil configured to seat in a recess at the proximal end of the axial passage of the occluder portion and the catch body is formed of an elastic material.

In another embodiment of the invention, the catch system for holding the occluder portion in the second configuration is of an adjustable catch-length in the axial direction.

According to another aspect of the invention, a collapsible medical device for occluding an aperture in a body is provided. The medical device has a first configuration with a reduced profile and a second configuration with an expanded profile and is adapted to be delivered through a delivery system into a desired delivery location. The medical device comprises an occluder portion that is adapted to move from a reduced profile configuration to an expanded profile configuration and the occluder portion includes an axial passage along the length of the occluder portion. The medical device further includes a catch system adapted to be disposed in the passage of the occluder portion such that the occluder portion can be moved from the reduced profile configuration to the expanded profile configuration with the catch member in the passage. The medical device further includes a catch member having an adjustable axial length, so that a catch distance provided by the catch member can be adapted to a dimension of the aperture when the device is delivered to the desired delivery location, a portion of the catch member configured to secure the proximal end of the occluder portion in the expanded profile configuration.

In another embodiment of the invention, the collapsible medical device further comprises a securement system for attaching the catch member to a delivery wire and attaching the occluder portion to a delivery catheter.

In another embodiment of the invention, the catch member includes a resilient spring that may optionally include an attachment piece that is adapted to attach to a deployment tool. In such embodiments, the attachment piece may includes a generally spherical ball.

In another embodiment of the invention, the proximal end of the catch member includes a T shape element for securing a proximal end of the occluder portion in the expanded profile configuration. According to another aspect of this embodiment, the T shape element may include an attachment piece that is adapted to attach to a deployment tool. The attachment piece may be a generally spherical ball.

According to another aspect of the invention, the occluder portion is made from at least one material selected from a biocompatible metal, a bioabsorbable polymer and a shape-memory polymer.

In another embodiment of the invention, the occluder portion in the first configuration is substantially cylindrical in shape and in the second configuration includes a distal set and a proximal set of petals, circumferentially arranged and radially oriented, adapted to provide compressive force on opposite sides of the aperture.

In another embodiment of the invention, the occluder portion is constructed from a substantially cylindrical portion of material with a proximal and a distal series of axial slits, each series of axial slits arranged circumferentially.

In another embodiment of the invention, the occluder portion is constructed from a series of axially-extending filaments arranged to form a substantially cylindrical occluder portion in the first configuration.

In another embodiment of the invention, a collapsible medical device for occluding an aperture in a body and a delivery system is provided. The medical device has a first configuration as a reduced profile and a second configuration as an expanded profile and is adapted to be delivered through the delivery system into a desired delivery location. The medical device comprises an occluder portion movable between a first and a second configuration that includes an axial passage along the length of the collapsible medical device with an adjustable-length center joint capable of expanding in an axial direction. The medical device further comprises a catch system for holding the occluder portion in the second configuration, including an catch member adapted to be disposed in the passage such that the occluder can move from the first configuration to the second configuration.

In another embodiment of the invention, the adjustable-length center joint includes a series of transverse slits, arranged longitudinally and capable of deforming to enable elongation of the adjustable-length center joint.

In another embodiment of the invention, the adjustable-length center joint includes a series of transverse creases, arranged longitudinally and capable of deforming to enable elongation of the adjustable-length center joint. In another embodiment of the invention, the adjustable-length center joint includes at least one spirally oriented cut, constructed and arranged to allow flexible deformation of the adjustable-length center joint. In another embodiment of the invention, wherein the adjustable-length center joint is of a braided construction capable of a range of the axial lengths in accordance with the dimension of the aperture and position of the device with respect to the aperture.

In another aspect of the invention, the adjustable-length center joint includes a first portion and a second portion, the first portion having an first cylinder with first circumferential features on an inner surface and the second portion having a second cylinder with second circumferential features on an outer surface; the second portion capable of being controllably inserted in the first portion such that the first features of the proximal portion and the second features of the distal portion are in contact and wherein contact between the first features of the proximal portion and second features of the distal portion secures said adjustable-length center joint at a selected length. According to another aspect of the invention, the first portion and the second portion are made of a resilient material capable of flexing. The first and second portions in some embodiments use a locking tab mechanism or a ratcheting grooves mechanism.

In one embodiment of the invention, the adjustable-length center joint includes: a first substantially cylindrical portion having a flexible tab or key protruding from an outer surface of the first substantially cylindrical portion, and a second substantially cylindrical portion having an axially-oriented groove and at least one locking bay adjacent to said groove, disposed along an inner surface of the second substantially cylindrical portion. The first substantially cylindrical portion is adapted to be controllably inserted in the second substantially cylindrical portion a selected distance and secured at the selected distance by rotating the first substantially cylindrical section enabling the flexible tab to engage with a locking bay and optionally applying radial force in the first substantially cylindrical portion to hold the flexible tab in place.

In another embodiment of the invention, the adjustable-length center joint includes: a first substantially cylindrical portion having a flexible tab protruding from an outer surface of the first substantially cylindrical portion, and a second substantially cylindrical portion having at least one circumferentially-oriented groove disposed along an inner surface of the second substantially cylindrical portion, and optionally. The first substantially cylindrical portion is adapted to be controllably inserted in the second substantially cylindrical portion a selected distance and secured at the selected distance by engaging the flexible tab on at least one circumferentially-oriented groove and by optionally applying radial force in the first substantially cylindrical portion to hold the flexible tab in place. In some embodiments, the flexible tab or key is replaced with a non-flexible tab or key.

In one embodiment of the invention, the adjustable-length center joint includes a first portion of substantially cylindrical shape having directional ratcheting grooves disposed on an inner surface of the first portion, and a second portion having a lesser diameter than the diameter of the first portion, having directional teeth disposed on an outer surface of the second portion adapted to engage the angled ratcheting grooves when the second portion is controllably inserted in the first portion thereby preventing separation of the first and second portions. According to another aspect of the invention, the first portion is a proximal portion and the second portion is a distal portion. According to yet another aspect of the invention, the inner surface of the first portion and the outer surface of the second portion are further contoured to provide substantial friction when the inner surface of the first portion is brought into contact with the outer surface of the second portion.

In another embodiment of the invention, the collapsible medical device is adapted to close a septal defect including a patent foramen ovale (PFO).

These and other aspects and embodiments of the disclosure are illustrated and described below

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS

Various embodiments of the present invention provide implants intended to facilitate occluding an aperture within body tissue. Aspects of the present invention include devices, delivery/retrieval systems and techniques for delivering such devices intended to occlude an aperture within body tissue. In particular and as described in detail below, the described occluder may be used for closing an ASD, ventricular septal defect (VSD) or PFO in the atrial septum of a heart. Although the embodiments are described with reference to an ASD, VSD or PFO, one skilled in the art will recognize that the devices and methods of the present invention may be used to treat other anatomical conditions. As such, the invention should not be considered limited in applicability to any particular anatomical condition. In addition, the systems and methods for delivery and retrieval, and for catching an occluder in a deployed state, which are aspects of the present invention, may also be used in connection with other types of devices besides an occluder, in particular, devices having tubular profiles.

In this application, the term “catch system” describes the portion/aspect of an implant that secures the device in the deployed configuration. The catch system may be a single piece or a group of connected or assembled pieces. In particular, the “catch member” is the portion of the catch system that engages with the occluder to hold the occluder in the deployed configuration and is described in more detail below.

In this application, “distal” refers to the direction away from a catheter insertion location and “proximal” refers to the direction nearer the insertion location. Additionally, the term “delivery configuration” refers to the configuration of a device, such as an occluder, when it has a reduced profile in a delivery catheter. The term “deployed configuration” refers to the configuration of the device, such as an occluder, when it has been deployed from the catheter, such as at the desired implantation location.

In this application, “catch distance” refers to the distance between the distal end and the proximal end of a catch member. The catch distance is related to the distance between the distal end and the proximal side of a deployed device, such as an occluder.

In this application, “adjustable” refers to a property of a device that can be varied, for example, according to variable anatomical geometry in individual patients, such as individual septal thickness. As will be described in greater detail below, the adjustability of the occluder device and corresponding catch member is a desirable feature. While occlusion may be constructed in a variety of sizes and dimensions, and preselected to approximately fit a particular size septal defect, an occluder device with an adjustable center-joint length permits a customized fit to the anatomical structure of the defect. An adjustable occluder has the advantage of allowing fine adjustments during implantation thereby allowing an optimal fit of the particular septal defect. In some cases an optimal fit might be achieved by angling an occlusion device to accommodate overlapping portions of septal tissue. As will be evident to one skilled in the art, optimal fit of a septal defect involves a finely tuned balance of clamping forces applied to the septa and precisely defined dimensions of an occlusion device. Thus, various embodiments of the present invention include adjustable-length occlusion devices that may be finely adjusted during implantation to achieve the optimal clamping forces.

FIG. 1illustrates a human heart10, having a right atrium11and a left atrium13and including various anatomical apertures18aand18b. The atrial septum12includes septum primum14and septum secundum16. The anatomy of the septum12varies widely within the population. In some people, septum primum14extends to and overlaps with septum secundum16. The septum primum14may be quite thin. When the anatomical aperture18ais present, blood could travel through the anatomical aperture18abetween septum primum14and septum secundum16(referred to as “the PFO tunnel”). Additionally or alternatively, blood could travel through anatomical aperture18b, referred to as ASD.

FIG. 2illustrates an exemplary occluder with which systems and techniques disclosed herein may be used. An occluder70, for example, is illustrated as deployed in the septum12of a heart. The device operates to close an aperture in the septum by covering both sides of the aperture. The reference numerals used to identify components of the described embodiment are disposed on multiple figures where the component is illustrated. The reference numerals are intended to facilitate an overall understanding of the invention and the relationship between components illustrated in different figures. The occluder70inFIG. 2is shown in a human heart in a deployed configuration with a catch member50engaged (much of the catch member is obscured by the central tube of the occluder).

FIG. 3illustrates the insertion of an occluder in a human subject122using a delivery assembly124in accordance with an aspect of the disclosure. A portion of delivery assembly124, including an occluder and a delivery mechanism for the occluder, which can be externally manipulated by a clinician, is inserted into the subject through an incision point126. The distal end of the delivery assembly124is advanced toward and into the heart10until the distal end is in proximity to the defect to be closed, as seen inFIG. 4.

The embodiment described below in conjunction withFIGS. 5-8has some similarities to the device disclosed in U.S. patent application Ser. No. 10/890,784, entitled Tubular Patent Foramen Ovale (PFO) Closure Device with Catch System, filed on Jul. 14, 2004; U.S. patent application Ser. No. 11/384,635, filed Mar. 20, 2006, entitled Catch Member for PFO Occluder; U.S. patent application Ser. No. 11/235,661, entitled Occluder Device Double Securement System for Delivery/Recovery of Such Occluder Device, filed Sep. 26, 2005; and U.S. patent application Ser. No. TBD, entitled Patent Foramen Ovale (PFO) Closure Device with Linearly Elongating Petals, filed Mar. 27, 2007, all of which have the same assignee as the present application, and are incorporated herein by reference in their entirety. These incorporated applications and additional applications incorporated below describe some ways in which a device can be formed from a tube or substantially cylindrical form provided by bonding a plurality of filaments, and how to deploy and deliver such a device.

As shown inFIGS. 5-8, the occluder70is formed from a tube (which can be extruded or rolled) that forms distal petals72produced by slits74in the distal portion of tube according to the cutting pattern shown inFIG. 5. As shown inFIG. 6, the distal portion20of the tube includes eight slits74that form eight extended segments of the tube that form the distal loops or petals72. As is apparent from the figures, the slits extend the entire distance of the distal portion of the tube between central tube78and distal end76so that loops of the same cross section are formed. Upon application of force Fdto distal end76, extended segments defined by slits74bow and twist outward to form distal petals72in distal side of the occluder70. The movement of the segments during deployment is such that the segments rotate in an orthogonal plane relative to the axis of the device. Central tube78may be constrained during the application of force Fd, or any combination of forces sufficient to reduce the axial length of the tube may be applied. One end of each of distal petals72originates from central tube78, while the other end originates from distal end76(FIGS. 6 and 7). Proximal petals82may be formed in proximal portion40, as shown inFIGS. 6-8, making slits84between central tube78and proximal end86, using the same cutting pattern described above and applying force Fpor combination of forces sufficient to reduce the axial length of the tube allowing slits84bow and twist outward to form proximal petals82in proximal portion40of the occluder70. One end of each of distal petals82originates from central tube78, while the other end originates from proximal end86.

The tube(s) forming occluder70may be formed from a biocompatible metal or polymer. In at least some embodiments, the occluder70is formed of a bioabsorbable polymer, or a shape memory polymer. Shape memory polymers can be advantageous so that the structure of the device assists in pressing the PFO tunnel closed. In other embodiments, the occluder70is formed of a biocompatible metal, such as a shape memory alloy (e.g., nitinol). The thermal shape memory and/or superelastic properties of shape memory polymers and alloys permit the occluder70to resume and maintain its intended shape in vivo despite being distorted during the delivery process. Alternatively, or additionally, the occluder70may be formed of a bioabsorbable metal, such as iron, magnesium, or combinations of these and similar materials. Exemplary bioabsorbable polymers include polyhydroxyalkanoate compositions, for example poly-4-hydroxybutyrate (P4HB) compositions, disclosed in U.S. Pat. No. 6,610,764, entitled Polyhydroxyalkanoate Compositions Having Controlled Degradation Rate and U.S. Pat. No. 6,548,569, entitled Medical Devices and Applications of Polyhydroxyalkanoate Polymers, both of which are incorporated herein by reference in their entirety.

The cross-sectional shape of tube may be circular or polygonal, for example, square or hexagonal. The slits74and84may be disposed on the face of the polygon (i.e., the flat part) or on the intersection of the faces.

The tube can be injection molded, extruded, or constructed of a sheet of material and rolled into a tube. The sheet of material could be a single ply sheet or multiple ply. The slits that form the segments could be cut or stamped into the sheet prior to rolling the sheet into a tube to connect the ends to form an enclosed cross section. Various geometrical cross sections are possible including circular, square, hexagonal and octagonal and the joint could be at the vertex or along the flat of a wall if the cross section is of a particular geometry. Various attachment techniques could be used to join the ends of the sheet to form a tube, including welding, heat adhesives, non-heat adhesives and other joining techniques suitable for in-vivo application. In some embodiments, the tubular body of the occluder70is provided by aligning and selectively bonding a plurality of filaments to leave openings similar to slits74and84. One of skill in the art will appreciate that references to occluder70and to a “tube” herein are generally applicable to an occluder70formed according to either technique.

The petal configuration, illustrated inFIG. 8, is the deployed configuration. The occluder70can be secured in the petal configuration by a catch system that holds the ends of the tube together, certain embodiments of which are described below.

The transformable design of occluder70enables the device to be delivered in a low profile, delivery configuration and to be converted readily, i.e., by reducing the axial length, in place to the high-profile deployed configuration. Moreover, the conversion can readily be effected by forcing distal end76and proximal end86together. For example, distal portion20and proximal portion40of occluder70may be deployed in separate steps, or both distal portion20and proximal portion40of occluder70may be exposed (e.g., out of the delivery catheter) prior to engaging the catch system and deployed together as the catch element is engaged. Use of the terms distal and proximal portion20and40, respectively, include the loops or other geometries and configurations that are formed on the distal and proximal sides, respectively.

Occluder70may be made in any one of several ways. Slits74and84may be cut such that the tube bends into its intended configuration following deployment in vivo. Specifically, slits74and84may be cut to produce segments72and82(as illustrated inFIGS. 5,6) of a thickness that facilitates the bending and formation of loops72and82(as illustrated inFIGS. 7,8) upon the application of forces Fdand/or Fpduring deployment. The segments72and82that form the loops are referenced with the same reference numeral. As an alternative, or additionally, a tube formed of a shape memory material may be preformed into its intended configuration ex vivo so that it will recover its preformed shape once deployed in vivo. According to at least some embodiments, this preforming technique produces more reliable deployment and bending of occluder70in vivo. An intermediate approach may also be used: the tube may be only slightly preformed ex vivo such that it is predisposed to bend into its intended shape in vivo upon application of forces Fdand/or Fp.

This particular type of occluder70and delivery sequences are described for purposes of illustration and explanation; of course, other types of occluders can be deployed using the deployment catch systems described herein. The catch member50, as illustrated, is disposed in an axial passage in a radially central location (although it could be offset) in the occluder70and is schematically illustrated as a separate piece than the occluder70. In a preferred embodiment, the catch member50may be fixed to one end of the tube that forms occluder70. For example, a distal flange92may be fixed to the distal tip39(shown inFIG. 6andFIG. 10) of the tube.

In general, references to “occluder70” herein may be inclusive of catch member50, depending on the context, for example, unless separately listed or otherwise stated. One end of tube, preferably the proximal end of the tube, is able to move with respect to the catch member50(and especially the catch system provided thereby) so that the distal and proximal petals72and82can move from the delivery configuration to the deployed configuration. The inside surface of the tube is able to slide over the catch member50so that, when the proximal end86of the occluder70rests against a proximal side (e.g. proximal side96or proximal stick296) of catch member50, the occluder70is secured in its deployed configuration.

The catch members described herein are for occluders in which the distance between the distal petals72and the proximal petals82in the deployed configuration is determined by the catch member and related to the catch distance, which is related to the axial length of the catch member in the permanent catch configuration. Compared to fixed-length catch systems, adjustable length catch systems of certain embodiments of the invention, described in more detail below, adjust the catch distance to the geometry of the septal defect that the accompanying device, such as an occluder, is implanted to close. By selecting the properties of materials and/or design for the adjustable length catch member, an adjustable length occlusion device can fit different patients with different defects, or be used for closing different types of defects. As such the length of the catch distance adjusts to the geometry of the septal defect to be closed, for example, by an occluder, and the adjustable length catch members provide appropriate clamping forces for tissues of different thickness, such as septa. In general, the adjustable length is provided by expandable design feature of the center joint of the occlusion device and an elastic feature of the catch member. As used herein, the terms “elastic” and “resilient” refer to a property of being stretchable, flexible or bendable from an original or rest shape, typically with a tendency to return to an original form. Generally, the materials and/or design for the elements of the catch member that allow for the adjustable catch distance are selected so that the force needed to stretch the adjustable portion of the occlusion device is greater than the force applied by the catch member to secure the occlusion device in its deployed configuration.

One embodiment of a catch system of the present invention will now be described with reference toFIGS. 9-14.FIG. 9Aillustrates a catch member50that can be disposed in the axial passage, which may be radially centric, of the occluder70. The catch member50includes a distal flange92that is disposed at the distal end of the occluder70. In some embodiments, the distal flange92of the catch member is fixed to the occluder70. In other embodiments, the distal flange92of the catch member50is not fixed to the occluder70, allowing the catch member50to rotate with respect to the occluder70. In one embodiment, the catch member50includes a distal shelf94that allows the distal side of the occluder70to move relative to the proximal side (where there is a Fpor Fdforce applied as described in preceding paragraphs). Typically the catch member50has an axial length of about 5-30 mm and a diameter of approximately 0.5-3 mm. Although a circular cylinder is illustrated, a variety of cross sectional shapes can by used effectively.

According to one embodiment of the invention, catch member50, as illustrated inFIGS. 9A-14, may be made of any metal or polymer suitable for forming a helical spring. In another embodiment, catch member50may be made of biocompatible metal or polymer.

In an alternative embodiment, catch member50may be made of shape memory material (e.g., nitinol). The thermal shape memory and/or superelastic properties of shape memory polymers and alloys permit the catch member50to resume and maintain its intended shape in vivo despite being distorted during the delivery and/or deployment process.

In an alternative embodiment, catch member50may be made of a bioabsorbable material. Exemplary bioabsorbable materials include polymers, such as polyhydroxyalkanoate compositions, for example poly-4-hydroxybutyrate (P4HB) compositions, disclosed in U.S. Pat. No. 6,610,764, entitled Polyhydroxyalkanoate Compositions Having Controlled Degradation Rate and U.S. Pat. No. 6,548,569, entitled Medical Devices and Applications of Polyhydroxyalkanoate Polymers, both of which are incorporated by reference in their entirety.

In a preferred embodiment, illustrated inFIGS. 9A and 9B, catch member50is made of elastic bioabsorbable polymer which can be stretched beyond its original length, for example to at least twice its original length. The catch member50includes a wire95that extends from the distal flange92to a proximal side96of the catch member. The wire95also forms a body portion98of the catch member. With continued reference toFIG. 9A, the body portion98is a helical spring configuration of wire95that can expand when pulled (tension applied). The proximal side96includes a spiral configuration102of wire95. The proximal end of the catch member50, i.e., the proximal end of the wire95includes a ball joint104so that the catch member50is connected to the delivery system by a clasper (not shown inFIGS. 9A and 9B) grasping the ball joint104.FIG. 9Billustrates an end view of the catch member50taken along lines9B-9B inFIG. 9A. The ball joint104can be centrally located in the proximal end of the catch member50(as illustrated) or it can be offset from the center.

FIGS. 10-14illustrate the deployment process of the occluder70. As illustrated inFIGS. 10-14, delivery system includes a delivery catheter130slidably disposed within delivery sheath (not shown), and a delivery wire140slidably disposed within the delivery catheter130. Delivery wire140includes a wire sheath142that surrounds an inner wire144with axially projecting arms146at its distal end. Each of the projecting arms146has a cup148disposed on the distal end of the projecting arms146. Although two projecting arms146are illustrated, according to one embodiment of the invention, three, four, five, six, or more projecting arms can be used. The cups148are sized and shaped to grasp the ball joint104of the catch member50and secure it when the arms146are disposed within the wire sheath142. In an alternative embodiment, the connection between delivery wire140and the ball joint104of the catch member50can be of a ball-claw feature as disclosed in U.S. patent application Ser. No. 10/389,471, entitled Coupling System Useful in Placement of Implants, which is incorporated by reference in its entirety.

FIG. 10is a cross sectional view of the distal end of the delivery assembly124. According to one embodiment of the invention, the proximal portion of the occluder70is secured to a delivery catheter130with a threaded connection and the ball joint104is secured with cups148of the projecting arms146to the inner wire144of the delivery wire140. In an alternative embodiment, the connection between delivery catheter130and occluder70could be any other suitable mechanism as described in, for example, U.S. patent application Ser. No. 11/235,661, incorporated by reference herein. As illustrated inFIG. 10, upon inserting the delivery assembly124to the desired location, delivery sheath (not shown) is withdrawn distally to expose the occluder70.

With reference toFIG. 1, a force Fpis applied to the delivery catheter130and a force Fdis applied to the delivery wire140, such that the proximal end of the catch member50extends proximally in an axial direction, while the occluder70is maintained at its implant location. As the delivery wire140, holding the ball joint104, is pulled proximally, the spiral section102extends beyond the proximal end of the occluder70, as illustrated inFIG. 1. The catch member can then be relaxed by stopping application of force Fdon the delivery wire140. As illustrated inFIG. 12, according to one embodiment of the invention, a conical shaped recess110on the proximal end of the occluder70could be incorporated for resting the spiral section102and preventing the catch member50from retracting further. Upon locking the occluder70in its deployed configuration, the spiral section102and distal flange92provide sufficient force to keep the occluder petals72and82compressed against the septum.

With reference toFIG. 13, the delivery catheter130is disconnected from the occluder70by disengaging the threaded connection between the delivery catheter130and the proximal end of the occluder70, and retracting the delivery catheter130proximally. At this point, the deployment of the occluder70can be assessed and if needed, occluder70can be retrieved. Upon satisfaction with the deployment, occluder70can be released. According to one embodiment of the invention, illustrated inFIG. 14, the release is effected by withdrawing the wire sheath142, which releases the ball joint104from the cups148of the projecting arms146. The delivery assembly124can then be withdrawn in the direction indicated by the arrow.

When the occluder70is in a deployed configuration, the body portion98of the catch member50can stretch in response to the pressure exerted on the petals by the septa, which is a function of the thickness of the septa between the distal petals72and the proximal petals82(shown, e.g., inFIG. 8). For example, a thicker septa will exert a larger force on the petals72and82, causing the body portion98of the catch member50to stretch more than a thinner septa, which will exert a smaller force on the petals. The axial length of the catch member50can therefore be adjusted and the occluder70can be adapted to the anatomy of individual defects during deployment.

In one embodiment, the occluder70can be retrieved by reversing the sequence of steps illustrated inFIGS. 10-14. For example, the inner wire144can be advanced distally to allow cups148to enclose the ball joint104of the catch member50. While holding the inner wire144in place, the wire sheath142is advanced distally to cause arms146to close and cups148to grasp the ball joint104, thereby securing the catch member50to the delivery wire140. While holding the delivery wire140in place, the distal end of the delivery catheter130is advanced distally and threaded onto the proximal portion of the occluder70, thereby securing the occluder70to the delivery catheter130. While holding the delivery catheter130steady, the delivery wire140is first pulled proximally to elongate the catch member50and then released, which causes the catch member50to slide into the central passage of the occluder70, thereby releasing the catch, as illustrated inFIG. 10. The occluder70can then be collapsed into its low profile configuration by advancing the delivery sheath distally or by withdrawing the delivery wire140and the delivery catheter130proximally. The occluder70can then be re-deployed, or if desired, withdrawn together with the delivery assembly124from the patient's body.

FIGS. 15-20illustrate another embodiment of the present invention.FIG. 15illustrates a catch member50athat is disposed in the central portion of the occluder70. The catch member50aincludes a distal flange292that is disposed at the distal end of the occluder70. In some embodiments, the distal flange292of the catch member is fixed to the occluder70. In other embodiments, the distal flange292of the catch member50ais not fixed to the occluder70, allowing the catch member50ato rotate with respect to the occluder70. In one embodiment, the catch member50includes a distal shelf294that allows the distal side of the occluder70to move relative to the proximal side (where there is a Fpor Fdforce applied as described in preceding paragraphs). Typically, the catch member50ahas an axial length of about −5-30 mm and a diameter of approximately 0.5-3 mm. Although a circular cylinder is illustrated, a variety of cross-sectional shapes can by used effectively.

With continuous reference toFIG. 15, according to one embodiment of the invention, the proximal end of catch member50aincludes a proximal stick296and a ball joint204at one end of the stick so that the catch member50ais connected to the delivery system by a clasper (not shown inFIG. 15) grasping the ball joint204. The proximal and distal ends of the catch member50acan be formed of a relatively rigid material, while the middle portion of the catch member50acan be made of a more elastic material. According to one embodiment of the invention, the ball joint204is at one end of the proximal stick296as illustrated inFIG. 15.

According to one embodiment of the invention, catch member50a, as illustrated inFIGS. 15-20, may be made of any metal or polymer with elastic property. In another embodiment, catch member50amay be made of biocompatible metal or polymer.

In one embodiment, catch member50amay be made of shape memory material (e.g., nitinol). The thermal shape memory and/or superelastic properties of shape memory polymers and alloys permit the catch member50ato resume and maintain its intended shape in vivo despite being distorted during the delivery and/or deployment process.

In one embodiment, catch member50amay be made of a bioabsorbable material. Exemplary bioabsorbable materials include polymers, such as polyhydroxyalkanoate compositions, for example poly-4-hydroxybutyrate (P4HB) compositions, disclosed in U.S. Pat. No. 6,610,764, entitled Polyhydroxyalkanoate Compositions Having Controlled Degradation Rate and U.S. Pat. No. 6,548,569, entitled Medical Devices and Applications of Polyhydroxyalkanoate Polymers, both of which are incorporated by reference in their entirety.

In a preferred embodiment, illustrated inFIG. 15, at least a portion of catch member50ais made of elastic bioabsorbable polymer which can be stretched beyond its original length, for example to at least twice its original length. The catch member50aincludes a middle portion295that extends from the distal flange292to a proximal stick296of the catch member50a.With continued reference toFIG. 15, the middle portion295of the catch member50acan expand when pulled (tension applied). In the embodiment illustrated inFIG. 15, the proximal stick296is perpendicular to the middle portion295. At least one end of the proximal stick296comprises a ball joint204so that the catch member50ais connected to the delivery system by a clasper (not shown inFIG. 15) grasping the ball joint204. The ball joint204can be located at the end of the proximal stick296(as illustrated), or it can be anywhere between an end and the junction of the proximal stick296and the middle portion295.

FIGS. 16-20illustrate the deployment process of the occluder70. As illustrated inFIGS. 16-20, delivery system includes a delivery sheath (not shown), a delivery catheter130slidably disposed within delivery sheath (not shown), and a delivery wire140slidably disposed within the delivery catheter130. Delivery wire140includes a wire sheath142that surrounds an inner wire144with axially projecting arms146at its distal end. Each of the projecting arms146has a cup148disposed on the distal end of the projecting arms146. Although two projecting arms146are illustrated, according to one embodiment of the invention, three, four, five, six, or more projecting arms can be used. The cups148are sized and shaped to grasp the ball joint204of the catch member50aand secure it when the arms146are disposed within the wire sheath142. In an alternative embodiment, the connection between delivery wire140and the ball joint204of the catch member50can be of a ball-claw feature as disclosed in U.S. patent application Ser. No. 10/389,471, entitled Coupling System Useful in Placement of Implants, which is incorporated by reference in its entirety above.

FIG. 16is a cross-sectional view of the distal end of the delivery assembly124. According to one embodiment of the invention, the proximal portion of the occluder70is secured to a delivery catheter130with a threaded connection and the ball joint204is secured with cups148of the projecting arms146to the inner wire144of the delivery wire140. As illustrated inFIG. 16, upon inserting the delivery assembly124to the desired location, delivery sheath (not shown) is withdrawn distally to expose the occluder70. In an alternative embodiment, connection between delivery catheter130and occluder70could be any other suitable mechanism as described in, for example, U.S. patent application Ser. No. 11/235,661, incorporated by reference herein. As illustrated inFIG. 16, upon inserting the delivery assembly124to the desired location, delivery sheath (not shown) is withdrawn distally to expose the occluder70.

With reference toFIG. 17, a force Fpis applied to the delivery catheter130and a force Fdis applied to the delivery wire140such that the proximal end of the catch member50aextends proximally in an axial direction while the occluder70is maintained at its implant location. As the delivery wire140, holding the ball joint204, is pulled proximally, the proximal stick296extends sufficiently beyond the proximal end of the occluder70, as illustrated inFIG. 17. The catch member can then be relaxed stopping application of force Fdon the delivery wire140. As illustrated inFIG. 18, the proximal stick296has a greater dimension than the inner diameter of the proximal section of the occluder70, thus preventing the catch member50afrom retracting further. Upon locking the occluder70in its deployed configuration, the proximal stick296and distal flange292provide sufficient force to keep the occluder petals72and82compressed against the septum.

With reference toFIG. 19, the delivery catheter130is separated from the occluder70by disengaging the threaded connection between the delivery catheter130and the proximal end of the occluder70, and retracting the delivery catheter130proximally. At this point, the deployment of the occluder70can be assessed and, if needed, occluder70can be retrieved. Upon satisfaction with the deployment, occluder70can be released. According to one embodiment of the invention, as illustrated inFIG. 20, the release is effected by withdrawing the wire sheath142, which releases the ball joint204from the cups148of the projecting arms146. The occluder70is held in the deployed configuration as illustrated inFIG. 20by the catch member50a. Upon satisfactory deployment of the occluder70, the delivery assembly124can be withdrawn in the direction indicated by the arrow.

When the occluder70is in a deployed configuration, the middle portion295, or a part thereof, of the catch member50a, can stretch in response to the pressure exerted on the petals by the septa, which is a function of the thickness of the septa between the distal petals72and the proximal petals82(shown, e.g., inFIG. 8). For example, a thicker septa will exert a larger force on the petals, causing the body portion298of the catch member50ato stretch more than a thinner septa, which will exert a smaller force on the petals. The length of the catch member50ais therefore adjustable. The occluder70can therefore be adapted during deployment to occlude apertures in which the septal tissue has different thicknesses.

In one embodiment, the occluder70can be retrieved by reversing the sequence of steps illustrated inFIGS. 16-20. For example, the inner wire144can be advanced distally to allow cups148to enclose the ball joint204of the catch member50a. While holding the inner wire144in place, the wire sheath142is advanced distally to cause arms146to close and cups148to grasp the ball joint204, thereby securing the catch member50ato the delivery wire140. While holding the delivery wire140in place, the distal end of the delivery catheter130is advanced distally and threaded onto the proximal portion of the occluder70, thereby securing the occluder70to the delivery catheter130. While holding the delivery catheter130steady, the delivery wire140is first pulled proximally to reduce the radial dimension of the catch member50aby increasing the angle between the ball joint-bearing side204of the proximal stick296and the body portion298of the catch member50a. The delivery wire140is then released, which causes the catch member50ato slide into the central passage of the occluder70, thereby releasing the catch, as illustrated inFIG. 16. The occluder70can then be collapsed into its low profile configuration by advancing the delivery sheath distally or by withdrawing the delivery wire140and the delivery catheter130proximally. The occluder70can then be re-deployed, or if desired, withdrawn together with the delivery assembly124from the patient's body.

The adjustable length catch members described hereinabove are preferably used with occluders having a matched adjustable-length center joint. The occluder70described above may have the added feature of an adjustable-length center joint, which may be preferred for certain applications.FIG. 21illustrates an exemplary occluder70A with an adjustable-length center joint with which systems and techniques disclosed herein may be used. An adjustable-length center joint occluder70A, for example, is illustrated as deployed in the septum12of a heart.

Like the occluder70shown inFIGS. 5-8, the occluder70A shown inFIGS. 22-25is formed from a tube (which can be extruded or rolled) that forms distal petals72produced by slits74in the distal portion of tube. The slits74in the distal portion of the tube are arranged according to the cutting pattern shown inFIG. 22. As shown inFIG. 23, the distal portion20of the tube includes eight slits74that form eight extended segments of the tube that form the loops or petals72. As apparent from the FIGS., the slits extend along the entire length of the distal end of the device so that the loops of the same cross section are formed. Upon application of force Fdto distal tip76, extended segments of the tube defined by slits74bow and twist outward to form distal petals72in distal side of the occluder70A. The movement of the segments during deployment is such that the segments rotate in an orthogonal plane relative to the axis of the device. Unlike the particular embodiment of the occluder70shown inFIGS. 5-8, the present embodiments of the occluder include a central tube78A with the added feature of being expandable, as described below. Expandable central tube78A may be constrained (e.g., held within the confines of the catheter) during the application of force Fd. Any combination of forces sufficient to reduce the axial length of the tube may be applied, for example a combination of pulling and pushing may be used. One end of each of distal petals72originates from central tube78A, while the other end originates from distal tip76(FIGS. 23,24). In a manner similar to that used to form the distal petals, the proximal petals82may be formed in proximal side40, as shown inFIGS. 23-25. Proximal petals82are formed by making slits84between central tube78and proximal end86, using the same cutting pattern described above. Force Fpcan be used to create the proximal petals82.

The petal configuration, illustrated inFIG. 25, is the deployed configuration. The occluder70A with adjustable center joint can be secured in the petal configuration by a catch system that holds the ends of the tube together, certain embodiments of which are described herein.

The embodiments described herein, for example in conjunction withFIGS. 22-25, have some similarities to, or can be used in combination with, devices and delivery assemblies and techniques described in U.S. patent application Ser. No. 10/890,784, cited above; U.S. patent application Ser. No. 11/395,718, entitled Tubular Patent Foramen Ovale (PFO) Closure Device with Catch System, filed Mar. 31, 2006; U.S. patent application Ser. No. 11/070,027, entitled Delivery/Recovery System for Clover Leaf Septal Occluder, filed on Mar. 2, 2005; U.S. patent application Ser. No. 11/235,661, cited above; U.S. patent application Ser. No. 11/384,635, cited above; U.S. patent application Ser. No. 11/121,833, entitled Catching Mechanism for Tubular Septal Occluder, filed May 4, 2005; U.S. Patent Application No. 60/787,988, entitled Deformable Flap Catch Mechanism for Occluder Device, filed Mar. 31, 2006; U.S. Patent Application No. 60/787,987, entitled Screw Catch Mechanism for Occluder and Method of Use, filed Mar. 31, 2006; U.S. patent application Ser. No. 11/644,373, entitled Catch Members for Occluder Devices, filed Dec. 21, 2006; U.S. patent application Ser. No. TBD, entitled Patent Foramen Ovale (PFO) Closure Device with Linearly Elongating Petals, cited above; U.S. Patent Application No. 60/847,703, entitled Implant-Catheter Attachment Mechanism Using Snare and Method of Use, filed Sep. 28, 2006; all of which have the same assignee as the present application and are incorporated by reference in their entirety. Additionally, U.S. Publication US20050234509A1, entitled Center Joints for PFO Occluders, is incorporated by reference in its entirety. These incorporated documents describe some ways in which a device can be formed from a tube or substantially cylindrical form provided by bonding a plurality of filaments, and how to deliver such a device.

The transformable design of occluder70A enables occluder70A to be delivered in a low profile, tubular form and to be converted readily, i.e., by reducing the axial length, in place to the high-profile deployed configuration. Features of the transformable design and deployment steps are detailed above and apply to the present embodiments.

Occluder70A may be prepared for delivery to an aperture18in any one of several ways, detailed above. Slits74and84may be cut such that the tube bends into its intended configuration following deployment in vivo. Specifically, slits74and84may be cut to produce segments72and82(as illustrated inFIGS. 22,23) of a thickness that facilitates the bending and formation of loops72and82(as illustrated inFIGS. 24,25) upon the application of forces Fdand/or Fpduring deployment. The reference numerals72and82refer to the segments of material in a straight form and a looped form. As an alternative, or additionally, a tube formed of a shape memory material may be preformed into its intended configuration ex vivo so that it will recover its preformed shape once deployed in vivo. According to at least some embodiments, this preforming technique produces more reliable deployment and bending of occluder70A in vivo. An intermediate approach may also be used: tube may be only slightly preformed ex vivo such that it is predisposed to bend into its intended shape in vivo upon application of forces Fdand/or Fp.

FIG. 21, likeFIG. 2, shows a deployed occluder70A in a human heart with a catch member50engaged. As noted above the term “catch system” describes the portion/aspect of the implant that secures the occluder in the deployed configuration. The “catch member” is the portion of the catch system that engages with the occluder to hold the occluder in the deployed configuration. The configuration illustrated is a slightly simplified schematic view of the occluder70A, shown in greater detail inFIGS. 22-25.

This particular type of occluder70A and delivery sequences are described for purposes of illustration and explanation. Other types of occluders can be deployed using the deployment catch systems described herein. The catch member50, as illustrated generally inFIGS. 24 and 25, is disposed in an axial passage, disposed in a radially central location, in the occluder70A and is schematically illustrated as a separate piece than the occluder70A. In one embodiment, the catch member may be attached to the distal end of the tube that forms occluder70A as illustrated inFIG. 24. For example, a shelf that is fixed to an elongate piece of the catch member can rest against the distal tip of the occluder. This is described further and illustrated withFIGS. 28Aand accompanying text.

One end of tube of the occluder70A is able to move with respect to the catch member50(and especially the catch system) so that the distal and proximal petals72and82can move from the delivery configuration to the deployed configuration. The inside surface of the tube is able to slide over the catch member50so that, when the proximal end of the catch member rests against a proximal surface of occluder70A, the occluder is secured in its deployed configuration. The catch member50is included in the catch system that includes a portion for connection to the delivery/recovery system, including, for example, a ball illustrated and described in more detail below.

As detailed inFIG. 3, the occluder70A is inserted in a human subject122using delivery assembly124and is secured in its deployed configuration. The expandable center joint will now be described with reference toFIGS. 26-34B.FIG. 26illustrates the catch member50that is adapted to be disposed in the central portion of the occluder70A. The catch member50includes a distal side2102that is disposed at the distal end of the occluder70A. In some embodiments, the distal side2102of the catch member is fixed to the occluder. In other embodiments, the catch member is allowed to rotate with respect to the occluder. In one embodiment, the catch member includes a distal shelf2104that rests against the distal tip of the catch member, allowing the distal side of the occluder to be moved along with the catch member relative to the proximal side when there is a Fpor Fdforce applied as described in preceding paragraphs. Typically the catch member has an axial length of about 15 mm and a diameter of approximately 5 mm. Although a circular cylinder is illustrated, a variety of cross sectional shapes can by used effectively.

FIGS. 26-27illustrate a detail view of an occluder70A according to an embodiment of the present invention. As illustrated, the center joint78A includes a spiral cut180that allows the joint to expand in an axial direction. The cut can be made using laser, heat, a razor, or other suitable techniques. As illustrated there are four turns in the spiral cut. More or fewer turns may be used to accomplish the axial elongation. Small holes182may be disposed at the end of the spiral cut to relieve stresses and reduce the possibility of tearing, splitting such that the cut would extend beyond the desired length. Occluder70A can be used with catch members of different fixed lengths, selected based on the requirements of an individual patient. However, use with an adjustable-length catch member as described herein is preferred. Catch member50is designed to keep the device in the deployed configuration. Only a portion of the catch member50is illustrated.

FIG. 27illustrates a thicker septum primum and secundum14a,16a, which causes the axial length of the device to expand when the device is deployed at the delivery site. Specifically, as illustrated, the spiral cut180allows the center joint to elongate so that the device can securely fit within septums of different dimensions. This allows a single occluder to be used in a number of different sized septums. Additionally, sometimes the PFO is angled, as illustrated inFIG. 1, and the length of the PFO, because of the angle, would require a center joint that is longer than if the PFO tunnel was not angled. The expandable center joint can accommodate PFO tunnels that are at a variety of angles.

FIGS. 28A and 28Bare views of a catch system deployed according to an embodiment of the present invention. In particular,FIG. 28Aillustrates the catch member50and a coil spring152which applies elastic compressive force to keep the occluder in the deployed condition. An expanded spiral portion154at the proximal end presses against the proximal end of the occluder tube86. A ball104is configured to attach to the delivery system (not shown) to allow the catch member to be pulled through the occluder (or the occluder to be pushed with respect to the catch member) to deploy the device.FIG. 28Billustrates an alternative catch member formed with elastic middle portion in the catch member that pulls the bands together.

There is a balance of forces that desirably secures the occluder in place without compressing the septum in a manner that would produce an adverse tissue reaction. If the force applied by the catch member is too great, the tissue between the occluder petals could have an adverse reaction.

For occluders with adjustable length center joints78A, the optimum fit for each patient is achieved by either choosing a proper length catch member or by incorporating the adjustable length catch member disclosed earlier.

FIGS. 29A,29B,30A,30B,31A and31B are detail views of alternative constructions of expandable center joints. In particular,FIGS. 29A and 29Billustrate a center joint400in the reduced axial dimension and the expanded axial dimension, respectively. Reference numeral402designates the inner lumen of the center joint. The center joint includes transverse slits arranged longitudinally, identified by reference numerals410,412, and414. The slits have holes at the edge of the slits to reduce material stresses and avoid tearing or splitting when the device is expanded. When the device is pulled in the axial dimension by a force Fp, the slits expand and allow the center joint to elongate. Specifically, the slit410may form a shape illustrated inFIG. 29B. The slits412form a triangular shape as illustrated. The openings in the slit are designed to be in the PFO tunnel and not allow for thrombos formation. Of course more or fewer slits can be used and the length of the slits can be modified to adjust the amount of force required to elongate the center joint.

FIGS. 30A and 30Billustrate a tubular center joint430in the reduced axial dimension and the expanded axial dimension, respectively. The figures show a cross sectional view of a tubular, creased portion of the center joint430. In this embodiment, the center joint is constructed of creases, e.g.,442,444and446that form angles A, B and C. When an axial force Fpis applied to the center joint430, the creases442,444, and446unfold and the angles A, B and C increase and the length of the center joint expands. The distance between the creases can be increased or decreased and the number of creases can be varied. Although illustrated such that the creases are in a zig-zag orientation (that is, the vertex of the top creases matches the vertex of the bottom creases), an alternate embodiment uses a crease alignment in which the vertex of the top matches the nadir of the bottom.

FIGS. 31A and 31Billustrate a center joint460in the reduced axial dimension and the expanded axial dimension, respectively. Similar to the creases in the embodiment disclosed inFIGS. 30A and 30B, the embodiment has smooth ridges, e.g.,472,474and476. Upon the application of Fp, the ridges allow the center joint to elongate as illustrated inFIG. 31B.

In an alternate configuration, the center joint is of a braided construction such that the braids allow for variation of the axial dimension of the center joint, based on the thickness of the septum and the angle of the PFO tube.

FIGS. 32-41illustrate a general telescoping center joint design with different detail embodiments for the occluders where the center joint can be adjusted according to the individual anatomical structure of the septal defect. Specifically, these embodiments use a telescoping feature in the center joint that allows the center joint to axially elongate. In some of the embodiments, there is a locking mechanism that keeps the center joint in the elongate configuration. One of skill in the art will appreciate that in some embodiments described, the length of the center joint is self-adjusting. Whereas in some embodiments described above, the length of the center joint is automatically adjusted and determined solely by the dimension of the aperture and more particularly by the thickness of the surrounding septal tissue, in some embodiments, the length of the center joint can be controllably adjusted by the clinician. One advantage of certain such embodiments is that the degree of clamping force provided by the distal and proximal sides of occluder70A can be readily controlled. In general, according to one embodiment of the invention, a telescoping center joint includes an outer tube and an inner tube that have a telescoping interference fit. In such embodiments, the tube providing the body of the occluder is understood to refer to the generally tubular shape of the body of occluder, which here has a two-piece construction. The center joint may be made with resilient material that allows some bending and flexing. In one embodiment, the outer tube is the proximal portion of the center joint and the inner tube is the distal portion of the center joint. In an alternative embodiment, the outer tube is the distal portion of the center joint and the inner tube is the proximal portion of the center joint.

FIGS. 32A,32B,33A,33B,34A and34B are detail views of other embodiments of the present invention. With specific reference toFIGS. 32A and 32Bwhich show a telescoping center joint in a reduced axial length and an expanded axial length. In one embodiment, the outer tube492includes a circumferential inward projecting rim496that is adapted to fit within the circumferential groove498on the inner tube492and lock the telescoping pieces together. As a result, the center joint can be locked in an extended form illustrated inFIG. 32B. Additionally, a number of circumferential grooves can be used in the inside center joint to allow for a variable length in the axial dimension. In an alternative embodiment, the circumferential outward projecting rim704could be on the outer surface at the end of the inner tube while the circumferential groove702could be on the inner surface along the axial length of the outer tube, as illustrated inFIGS. 40-41. The circumferential grooves702could also be angled to be directional, as illustrated, thus permitting the two portions to slide together easily and then be locked together. According to one embodiment of the invention, the rim-groove design is not limited to what has been illustrated. One skilled in the art should realize that any suitable rim-groove design can be incorporated herein. In particular, for example, the interval between grooves could have any length that is suitable for a desired application.

FIGS. 33A and 33Billustrate a simplified telescoping design where the maximum axial length is determined but the pieces are able to slide within a range up to the maximum axial length. In particular the center joint310includes an outer tube312and an inner tube314. The inner tube has an outwardly facing annular protrusion316(a square shape is illustrated but it could be any shape). The outwardly facing surface of the protrusion is fitted to slide within the inner surface320of the tube312. The outer tube310also includes an inwardly facing annular protrusion318that prevents the inner tube314from sliding out of the outer tube312.

FIGS. 34A and 34Bare similar to the annular lock ofFIGS. 32A and 32Bbut a threaded connection is provided instead of the annular protrusion. Specifically, a center joint330includes an outer tube332and inner tube334that slides within the tube. The end of the inner tube that is within the outer tube includes outwardly facing threads338that are adapted to be received by the inwardly facing threads336on the outer tube332. When twisting force Ftis applied to the center joint inner and/or outer tube the center joint locks into its elongate condition. In some embodiments in which only a portion of inner tube334has threads338, the entire length of outer tube includes threads336, except for a small end portion, such as portion339. Similarly, in embodiments in which only an end portion of outer tube332has threads336, almost the entire length of inner tube334, except for a small end portion, has threads338. This prevents the two halves from coming apart.

Referring now toFIG. 35, detail views of an adjustable-length center joint78A of an occluder70A with twisting tab-locking mechanism, according to other embodiments of the present invention, are provided.FIGS. 35A and 35Cillustrate the inner tube503of center joint78A.FIG. 35Billustrates the outer tube505of the center joint78A. The inner tube503of center joint78A depicted inFIG. 35Aincludes a key (or protrusion)504at its outer surface. In a preferred embodiment, the key504is at the end of the inner tube. Alternatively, the key504can be at any place along the length of the inner tube.FIG. 35Cshows the cross-sectional view of the inner tube503shown from a side in which the key504is evident.FIG. 35Billustrates the outer tube505, which has a length-adjustment channel506with locking bays on its inner surface. The locking bays are designed to fit the key504of the inner tube503. The key504is preferably not flexible. During deployment of occluder70A, the inner tube503is inserted into outer tube505with key504aligned with length adjustment channel506. Inner tube503is slotted into outer tube505the desired distance and then secured or locked by twisting507inner tube503. By twisting507inner tube503, key504is positioned in one of the locking bays along length adjustment channel506. Catch member501, as illustrated inFIGS. 9 and 15, is then introduced into the inner tube503to secure the occluder in the deployed configuration. The catch member applies an axial compression force to the occluder thereby securing the adjustable-length center joint78A at the desired length. The length of the center joint78A helps control the clamping force the occluder70A applies to the septal tissue. In an alternative embodiment, the key504is situated on the inside surface of the outer tube505while the length adjusting channel506and locking bay are on the outer surface of the inner tube503.

FIG. 36shows detail views of an adjustable center joint with a sliding tab-locking mechanism according to another embodiment of the invention. Like the embodiment discussed above inFIG. 35, the present embodiment has a inner tube513, depicted inFIG. 36A, and an outer tube515, depicted inFIG. 36B. The inner tube513shown inFIG. 36Ahas a flexible tab519with a key514that protrudes from the surface of the flexible tab519which can be flexibly deformed to align the outer surface of key514with the outer surface of the inner tube513. The inner tube513has a flexible tab519portion that is defined by slits provided in the end portion extending along the length of inner tube503as illustrated inFIG. 36C. The outer tube515, shown inFIG. 36B, has a series of discrete locking bays516disposed in a portion of the surface of the outer tube515. Adjustability of center joint78A (of occluder70A) is provided by sliding the inner tube513into the outer tube515the desired distance. Unlike the twisting tab-locking mechanism depicted inFIG. 35, the adjustable center joint shown inFIG. 36is locked in position when flexible tab519follows motion517(due to the flexible nature of the design and/or the elastic nature of the material selected) causing key514to engage in one of the discrete locking bays516. Catch member511, as illustrated inFIGS. 9 and 15, is then introduced into the inner tube513to secure the occluder in the deployed configuration. The catch member511applies apply force on flexible tab519in the selected locking bay, causing key514to engage in the locking bay516thereby securing the adjustable-length center joint78A at the desired length. Similar to previous embodiments, the length of the center joint78A helps control the clamping force the occluder70A applies to the septal tissue. In an alternative embodiment, the flexible tab519and key514are situated on the inside surface of the outer tube515while locking bay516is on the outer surface of the inner tube503. According to one embodiment of the invention, the key-locking bay design is not limited to what has been illustrated. One skilled in the art should realize that any suitable key-locking bay can be incorporated herein, such as the one illustrated inFIG. 37.

Turning now toFIGS. 38 and 39, the adjustable center joint78A of occluder70A may feature a friction-based adjustment mechanism, in certain embodiments.FIG. 38Ashows a cross-sectional view of outer tube601according to an embodiment of the invention.FIG. 38Bshows a cross-sectional view of inner tube603according to the same embodiment of the invention. As shown inFIG. 39A, inner tube603may be inserted into outer tube601, with friction at the surface615between the inner and outer tubes603and601.FIG. 39Billustrates an exploded view of a section of the surface615according to one embodiment of the present invention. Surface615may be contoured to increase the friction between the inner and outer tubes603and601. In alternate embodiments, the surface may also include positive stops or spaces whereby the inner and outer tubes603and601stop or lock in a selected position to prevent the two portions from sliding too freely or quickly. In these embodiments, the adjustable center joint78A with the friction based adjustment mechanism shown inFIGS. 38 and 39can include a safety mechanism to prevent the inner and outer tubes603and601from separating.

As illustrated by the embodiments described herein, the invention includes a telescoping adjustable-length center joint, which can have a variety of constructions. Any suitable construction whereby the length is adjustable and the two halves are prevented from separating.

The embodiments and techniques described here are described preferably for use with an occluder device made of a polymer and formed from a tubular or substantially cylindrical body. The occluder body or the catch mechanism as described in the embodiments above could be used with devices formed from many pieces, and including devices formed from other materials, including metals, polymers, stainless steel or nitinol.

The term “bioabsorbable,” as used in the description above, is also understood to mean “bioresorbable.”

In cases in which the implant is made of a polymer, it can be desirable to add an additive or coating to the material to make it radiopaque to make it more visible in a wider variety of imaging techniques.

While preferred embodiments of the present invention may specify proximal and distal ends or portions of devices, in other embodiments, it may be preferable to interchange the ends or portions. Distal and proximal should be construed as one orientation of devices in particular applications and should not be construed as restrictive.

It will be appreciated that while a particular sequence of steps has been shown and described for purposes of explanation, the sequence may be varied in certain respects, or the steps may be combined, while still obtaining the desired deployment or in some cases to effect deployment in a particular way. For example, the delivery sheath may be advanced or retracted at varying times and in varying degrees, the proximal and distal portions of the occluder may be deployed into the petal configuration in a different sequence, etc. In addition, the steps could be automated.

The illustrated embodiments and related description have been provided by way of example, and are not intended to be limiting. One of skill in the art will appreciate that variations can be made thereto without departing from the spirit and scope of the invention as indicated in the appended claims.