Patent Description:
Coil embolization is a commonly practiced technique for treatment of brain aneurysm, arterio-venous malformation, and other conditions for which vessel occlusion is a desired treatment option, such as, for example, in the occlusion of a tumor "feeder" vessel. A typical occlusion coil is a wire coil having an elongate primary shape with windings coiled around a longitudinal axis. In a typical aneurysm coil embolization procedure, a catheter is introduced into the femoral artery and navigated through the vascular system under fluoroscopic visualization. The coil in its primary shape is positioned within the catheter. The catheter distal end is positioned at the site of an aneurysm within the brain. The coil is passed from the catheter into the aneurysm. Once released from the catheter, the coil assumes a secondary shape selected to optimize filling of the aneurysm cavity. Multiple coils may be introduced into a single aneurysm cavity for optimal filling of the cavity. The deployed coils serve to block blood flow into the aneurysm and reinforce the aneurysm against rupture. While the overall device is commonly referred to as a coil, some of the individual components of the device are also referred to as coils. For clarity, the device herein will most often be referred to as an embolic implant, though it will be understood that the terms embolic coil and embolic implant are interchangeable.

<CIT> discloses a device for in situ treatment of vascular or cerebral aneurysms comprising an occlusion device having a flexible, longitudinally extending elastomeric matrix member that assumes a non-linear shape to conformally fill a targeted site. The occlusion device comprises a flexible, longitudinally extending elastomeric matrix member, wherein the device assumes a non-linear shape capable of fully, substantially, or partially conformally filling a targeted vascular site. In one embodiment the vascular occlusion device comprises a first longitudinally extending structural element having a longitudinally extending lumen and an outer surface; a second longitudinally extending structural element extending through the lumen; and an elastomeric matrix member surrounding the outer surface, wherein the second structural member does not engage or attach to the first structural element or the elastomeric matrix.

<CIT> discloses a medical device for forming an embolism within the vasculature of a patient. More particularly, it discloses an occlusion device comprising an inner core covered with a polymer. The medical device encourages cellular attachment and growth while maintaining favorable handling, deployment and visualization characteristics.

The invention is defined by appended claim <NUM>. Some embodiments of the invention are described below. For clarity, not all features of each actual implementation are described in this specification. In the development of an actual device, some modifications may be made that result in an embodiment that still falls within the scope of the invention.

Beginning with <FIG>, an embolic implant according to the invention is illustrated. Embolic implant <NUM> is shown in its linear, primary shape, from a side elevation view. Embolic implant <NUM> extends from its proximal end <NUM> to its distal end <NUM>. Embolic implant <NUM> is an elongate device of considerable length, but the illustration of <FIG> is truncated, so that the device's features can be enlarged to show detail. In the illustration of <FIG>, primary coil <NUM> is visible. Primary coil <NUM> is formed of a wire coiled to have a primary coil diameter D1 of approximately <NUM> inches (<NUM>), although smaller diameters, and diameters as large as <NUM> inches (<NUM>), may instead be used. The pitch of the coil may be uniform as shown, or it may vary along the length of the coil, or different sections of the coil may be formed to have different pitches. The wire material selected for the coil is preferably one capable of fluoroscopic visualization, such as Platinum, Platinum/Iridium, Platinum/Tungsten, Palladium, or other suitable material. In one embodiment, the wire forming the coil has a diameter of approximately <NUM> - <NUM> inches (<NUM> - <NUM>). Primary coil <NUM> is formed from continuous turnings of a wire or other filament to form windings <NUM>, which extend essentially the length of primary coil <NUM>, from proximal end <NUM> to distal end <NUM>. Primary coil <NUM> terminates near distal end <NUM> in distal tip <NUM>. Distal tip <NUM> is constructed to provide an atraumatic tip at the leading end, or distal end <NUM> of embolic implant <NUM>. The portion of distal tip <NUM> that is visible in <FIG> can be molded or extruded from a suitable polymer such as polyester, low density polyethylene (LDPE), acrylic adhesive, or other material. Various alternative constructions of a distal tip according to the invention are discussed in detail below.

Also visible in <FIG> is proximal assembly <NUM>. Proximal assembly <NUM>, disposed at proximal end <NUM>, is made up of proximal constraint sphere <NUM>, fiber <NUM>, and knot <NUM>. Proximal assembly <NUM> and various alternative embodiments of a proximal assembly will be discussed in greater detail below. Proximal constraint sphere <NUM> can be fabricated from stainless steel, a polymer, or any other suitable material. Fiber <NUM> can be fabricated from polyethylene, ultra high molecular weight polyethylene (UHMWPE), polypropylene, or other suitable material. While the term "sphere" is used throughout this disclosure, it will be understood that in an alternative embodiment according to the invention may have a proximal constraint element that is not spherical. A proximal constraint element may be less than perfectly spherical, elliptic, cubic, or other suitable shape. A proximal constraint element according to the invention is configured to be releaseably retained by a delivery device (not pictured).

As mentioned above, embolic implant <NUM> is shown in its linear, delivery configuration. Embolic implant <NUM> may be delivered into the vasculature of a subject via a delivery catheter or comparable implant tool (not pictured), while embolic coil or embolic implant <NUM> is in its delivery configuration. Once delivered to a treatment site within the vasculature, embolic implant <NUM> will be released from the delivery system, and will revert to a secondary configuration. A secondary configuration according to the invention may be curved, hooked, J-shaped, spiral, helical, complex, spherical, or any other desirable three dimensional configuration. In the example of embolic implant <NUM>, the secondary configuration is complex. Embolic implant <NUM> is illustrated in its complex secondary configuration in <FIG>. In <FIG>, embolic implant <NUM> is no longer in a linear configuration, but rather is coiled or turned about itself in a complex, three dimensional array. The three dimensional array is advantageous for distributing the implant in a manner that will occlude blood flow in a vessel or in an aneurysm. Primary coil <NUM> and proximal end <NUM> are visible in <FIG>.

Referring now to <FIG>, a cutaway side view reveals some of the details of embolic implant <NUM>. In <FIG>, embolic implant <NUM> is illustrated in its primary delivery shape or configuration. In use, embolic implant <NUM> is constrained in and delivered in its primary configuration via a catheter delivery system. As embolic implant <NUM> is deployed from the distal end of a catheter, it will revert to its secondary configuration. A secondary configuration according to the invention may be curved, hooked, J-shaped, spiral, helical, complex, or any three dimensional configuration that is suitable for the therapeutic objectives for use of the device. An example of a complex configuration according to the invention is illustrated in <FIG>, and described in detail below.

In the delivery configuration illustrated in <FIG>, embolic implant <NUM> has a proximal end <NUM> and a distal end <NUM>. A primary coil <NUM> and an inner coil <NUM> extend from the proximal end <NUM> to the distal end <NUM>, and surround lumen <NUM>. Primary coil <NUM> is constructed of thin Platinum wire, and inner coil is constructed of soft, kink resistant Nitinol. Disposed at proximal end <NUM> of embolic implant <NUM> is proximal constraint assembly <NUM>. Proximal constraint assembly <NUM> is made of proximal constraint sphere <NUM>, fiber <NUM>, and knot <NUM>. Proximal constraint sphere <NUM> may be constructed from gold or tin solder, Platinum, Titanium, stainless steel, or other suitable material. Proximal bond <NUM> is disposed in an annular fashion near proximal end <NUM>, may be formed from polyester, acrylic adhesive, or other suitable material. The material forming proximal bond <NUM> may be reflowed or otherwise molded around the proximal end of primary coil <NUM>. Proximal assembly <NUM> prevents proximal constraint sphere <NUM> from entering lumen <NUM>. Proximal constraint sphere <NUM> also plays a role in the delivery of embolic implant <NUM>, and is configured to be releaseably retained by a delivery tool or device such as those disclosed in<CIT>.

Disposed at distal end <NUM> is distal assembly <NUM>. Defining distal assembly <NUM> are distal tip <NUM>, distal sphere <NUM>, and distal knot <NUM>. Within lumen <NUM>, and extending the length of lumen <NUM>, is fiber <NUM>. In addition to being disposed in lumen <NUM>, fiber <NUM> is disposed within and through an internal channel or through hole (not visible) of proximal constraint element or proximal constraint sphere <NUM>.

Fiber thus extends proximally through lumen <NUM>, through proximal constraint sphere <NUM>, and out of proximal constraint sphere <NUM> at proximal end <NUM>. Fiber <NUM> is knotted to form proximal knot <NUM>. Fiber <NUM> is thus anchored at the proximal end <NUM>. Proceeding in the opposite direction, fiber <NUM> extends distally of proximal constraint element <NUM>, through lumen <NUM>, and through distal sphere <NUM>, which has, similar to proximal constraint sphere <NUM>, an internal channel or through hole (not visible in <FIG>). During construction of implant <NUM>, fiber <NUM> is also knotted to form distal knot <NUM>. Fiber <NUM> is thus anchored at distal end <NUM>. Fiber <NUM> is stretch resistant, and may be constructed from a suitable polymer such as polyethylene, ultra high molecular weight polyethylene (UHMWPE), polypropylene, or other suitable material. Because fiber <NUM> is stretch resistant, it will prevent stretching of primary coil <NUM> and inner coil <NUM>, stretching which could potentially plastically deform the coils and interfere with the retractability of embolic implant <NUM> within a catheter, and potentially interfere with the ability of embolic implant <NUM> to reconfigure from its linear delivery configuration to its secondary configuration.

Distal sphere <NUM>, which also may in the alternative have different shape, is retained by atraumatic distal tip <NUM>. Atraumatic distal tip <NUM> is formed from a polymeric material such as polyester, an acrylic adhesive, or other suitable material. The material is injected, molded, reflowed, extruded, or otherwise placed around distal sphere <NUM>, fiber <NUM> and distal knot <NUM> to securely bond the components one to another and to form an atraumatic distal tip. The embedding or other retention of distal sphere <NUM> also serves to prevent distal sphere <NUM> from entering lumen <NUM>. Distal assembly <NUM>, in conjunction with proximal assembly <NUM>, thereby maintains tension upon fiber <NUM>, and helps prevent stretching and distortion of primary coil <NUM> and inner coil <NUM>.

Also disposed in lumen <NUM> is shape wire <NUM>. Shape wire <NUM> is anchored in and extends from proximal bond <NUM>, through lumen <NUM>, and to distal tip <NUM>. Wire <NUM> is formed from Nitinol or another suitable shape memory material. Wire <NUM> confers the desired complex secondary configuration on embolic coil <NUM>. The proximal end of shape wire <NUM> is retained by proximal bond <NUM>. The distal end of shape wire <NUM> is anchored to or secured by atraumatic distal tip <NUM>. Because shape wire <NUM> is constructed of Nitinol, it is highly kink resistant, and confers softness on embolic implant <NUM>, while at the same time reliably conferring a desired secondary shape on embolic implant <NUM>. In the alternative, a relatively thin platinum wire may be used to construct primary coil <NUM>, also conferring softness on embolic implant <NUM>, enhancing the safety of the device.

In an alternative embodiment (not pictured), shape wire <NUM> may be ground or otherwise formed so that it is of a smaller diameter at its proximal end relative to its distal end. The diameter of shape wire <NUM> may increase gradually or incrementally from proximal end <NUM> to distal end <NUM>. The resulting embolic coil would be of a more robust or a stiffer secondary shape at the distal end and a softer coil near the proximal end. The largest shape wire diameter would be a diameter based upon the level of robustness desired at the distal end of the device.

Alternative embodiments of the invention described above are illustrated in <FIG>. The embolic coils or embolic implants described below and illustrated in the figures have some elements in common with the embodiment illustrated in <FIG>, though some of the common elements are arranged in alternative configurations than the configuration of <FIG>. In order to be concise, the description of every detail of each element will not be repeated for each embodiment.

The embodiment illustrated in <FIG> will now be described. Embolic implant <NUM> has a proximal end <NUM> and a distal end <NUM>. Embolic implant <NUM> includes primary coil <NUM> and optional inner coil <NUM>, both of which surround lumen <NUM>. In the embodiment of <FIG>, primary coil <NUM> is constructed of Platinum, and inner coil <NUM> is constructed of Nitinol, though the coils may be constructed of other suitable materials and remain within the scope of the invention. Inner coil <NUM> may optionally be processed to impart shape memory characteristics. Proximal constraint assembly <NUM> is disposed at proximal end <NUM>. Fiber <NUM> is threaded through a through hole (not visible) of proximal sphere <NUM>, and knotted to form a first proximal knot <NUM>. Fiber <NUM> is also knotted to form a second proximal knot <NUM>. In an alternative embodiment, second proximal knot <NUM> is formed distal of the proximal end of coil <NUM>, permitting some sliding movement of proximal constraint assembly <NUM>. This sliding movement would be limited by proximal sphere <NUM> and knot <NUM>. After formation of second proximal knot <NUM>, during construction of implant <NUM>, polyester, or an acrylic adhesive is reflowed, molded, or otherwise disposed at the proximal end of primary coil <NUM>, to form proximal bond <NUM>. Proximal bond <NUM> is a solid structure that anchors or secures fiber <NUM> and second proximal knot <NUM>. Proximal bond <NUM>, proximal sphere <NUM>, fiber <NUM>, first proximal knot <NUM>, and second proximal knot <NUM> together define proximal constraint assembly <NUM>. Proximal bond <NUM> prevents proximal constraint sphere <NUM> from entering lumen <NUM>, helping to maintain tension on fiber <NUM>, and preventing stretching and deformation of primary coil <NUM> and secondary coil <NUM>.

Also secured by or anchored to proximal bond <NUM>, and extending distally through lumen <NUM>, is shape wire <NUM>. Wire <NUM> is embedded in or otherwise bonded to proximal bond <NUM> near proximal end <NUM>. Shape wire <NUM> is processed to impart a secondary shape on embolic implant <NUM>. The profile of shape wire <NUM> may be altered to exhibit either a consistent or varied profile along its length. A larger profile shape wire will exhibit a more robust shape, and a smaller profile shape wire will exhibit a softer coil. Shape wire <NUM> extends distally and is anchored to distal bond <NUM>. Distal bond <NUM> may be formed using similar techniques as those used to form proximal bond <NUM>. However, in the implant <NUM>, distal bond <NUM> defines a more ring-like structure than proximal bond <NUM>. Distal bond <NUM> surrounds the distal end of primary coil <NUM>.

Fiber <NUM> also extends distally, through lumen <NUM>, and through a through hole of distal sphere <NUM>. Fiber <NUM> is knotted to form distal knot <NUM> near distal end <NUM>. Distal bond <NUM> prevents distal sphere <NUM> from entering lumen <NUM> at distal end <NUM>. Both proximal bond <NUM> and distal bond <NUM> serve to maintain tension in stretch resistant member <NUM>, and to prevent stretching and potential elongation of primary coil <NUM> and inner coil <NUM>.

As mentioned above, prior to assembly of embolic implant <NUM>, a secondary configuration is conferred upon wire <NUM>. However, embolic implant <NUM> and wire <NUM> are constrained in a generally linear, or delivery configuration by a delivery catheter or comparable device so that embolic coil <NUM> may be delivered intravascularly. After delivery of embolic implant <NUM> to a vessel or within an aneurysm of a subject, wire <NUM> will revert from its linear delivery configuration to its secondary configuration (not pictured). Consequently, embolic implant <NUM> will also revert to its secondary configuration, such as, for example, the configuration illustrated in <FIG> above.

<FIG> illustrates a component of an alternative embodiment according to the invention. <FIG> illustrates only the distal assembly <NUM>, which in use would be disposed at the distal end of an embolic implant according to the invention. Distal assembly <NUM> can be used as an alternative to the distal assemblies illustrated in <FIG>, in the fabrication of an embolic coil or embolic implant. Distal assembly <NUM> includes the distal end of fiber <NUM>. Fiber <NUM> is knotted to form distal knot <NUM>. Material such as polyester, acrylic adhesive, or other suitable material is reflowed, molded, injected, or otherwise formed around fiber <NUM> and distal knot <NUM> to form atraumatic distal tip <NUM>. Distal tip <NUM> secures or anchors fiber <NUM> and distal knot <NUM>, maintaining tension on fiber <NUM>. Distal tip <NUM> also bonds to the distal end of primary coil <NUM>, a portion of which is shown in <FIG>, and to the distal end of shape wire <NUM>, to together form a component of distal assembly <NUM>.

<FIG> illustrates yet another alternative embodiment of a distal assembly according to the invention. Distal assembly <NUM> includes fiber <NUM>. Fiber <NUM> is passed through a tubing segment <NUM> and knotted to form distal knot <NUM>. Distal tip <NUM> is formed from a cured material such as polyester, acrylic adhesive, or other suitable material that is reflowed, molded, injected, or otherwise placed around and bonded with tubing segment <NUM>, fiber <NUM>, the distal end of primary coil <NUM>, and distal knot <NUM>. Distal end of shape wire <NUM> may also be anchored to distal tip <NUM> or mechanically locked with tubing segment <NUM>. Distal assembly <NUM> defines an atraumatic tip and maintains tension on fiber <NUM>.

<FIG> illustrates the distal end only of another alternative embodiment according to the invention. Distal assembly <NUM> is disposed at the distal end of primary coil <NUM>, shown in cross section in <FIG>. A polymer, such as, for example, polypropylene, is melted and reflowed to bond to the distal end of primary coil <NUM>, and to form atraumatic distal tip <NUM>. Also secured to distal tip <NUM> during the foregoing process are the distal ends of shape wire <NUM> and fiber <NUM>, which are embedded in distal tip <NUM>.

<FIG> illustrates an alternative embodiment of the proximal portion only of an implant according to the invention. Proximal assembly <NUM> includes proximal sphere <NUM>. Proximal loop <NUM> is formed from a wire that is formed into a loop, passed through a through hole of proximal sphere <NUM>, and welded to proximal sphere <NUM>. Polymer fiber <NUM> is in turn looped or threaded through proximal loop <NUM> to secure fiber <NUM> to proximal assembly <NUM>. Proximal bond <NUM> is bonded to the proximal end of primary coil <NUM>, in a fashion similar to the methods described above. Shape wire <NUM>, at its proximal end, is also bonded to or secured by proximal bond <NUM>. Proximal bond <NUM> prevents proximal sphere <NUM> from entering lumen <NUM>, and prevents stretching and/or permanent deformation of primary coil <NUM> and secondary coil <NUM>, the proximal ends of which are shown in <FIG>.

<FIG> illustrates another embodiment of a proximal assembly according to the invention. Proximal assembly <NUM> includes proximal constraint sphere <NUM>. Proximal constraint sphere <NUM> includes a through hole (not visible) through which wire <NUM> is threaded and then welded to proximal constraint sphere <NUM>. Wire <NUM> has a proximal end <NUM> and a distal end <NUM>. At the distal end <NUM> of proximal assembly <NUM>, wire <NUM> is flattened and drilled or otherwise processed to form hole <NUM>. Fiber <NUM> is threaded through hole <NUM>, and looped. Alternatively, two lengths of fiber <NUM> may be used in order to double the tensile strength of fiber <NUM>. Though not pictured in <FIG>, fiber <NUM> extends distally through the lumen of an embolic implant. Proximal bond <NUM> is formed in a similar fashion to that described above in relation to previously described embodiments, and bonds to the proximal end of primary coil <NUM> and optionally to the proximal end of shape wire <NUM>. When it is a component of an embolic coil, proximal constraint assembly <NUM> helps maintain tension on fiber <NUM> and prevents stretching and/or deformation of the embolic coil.

<FIG> illustrates an alternative embodiment of an embolic implant according to the invention. Embolic implant <NUM> exhibits many advantages over prior art implants, including proximal softness that enhances safety. Embolic implant <NUM> in particular exhibits progressively increasing softness from its distal end <NUM> to its proximal end <NUM>. In other words, distal end <NUM> exhibits a more robust secondary or three dimensional shape than does proximal end <NUM>. And proximal end <NUM> exhibits greater overall compliance and softness. An implant such as embolic implant <NUM> can be shape set to, upon release from the constraints of a delivery catheter, return to a shape such as, for example, the configuration illustrated in <FIG> will be discussed in greater detail below.

Embolic implant <NUM> is shown in cross section in <FIG>, in order that its features may be readily viewed. Embolic implant <NUM> includes primary coil <NUM>. Primary coil may be constructed from any of the materials suitable for the coils described above. Primary coil <NUM> includes an internal lumen <NUM>. Disposed in and extending through lumen <NUM> is fiber <NUM>. Also disposed in lumen <NUM> are elliptical hole washers <NUM>, one near proximal end <NUM> and one near distal end <NUM>. (The term elliptical hole washers is used herein to describe a washer having a round hole and an elliptical hole. It will be understood that any washer having a plurality of holes or apertures may be used to form an embodiment within the scope of the invention. ) Fiber <NUM> is threaded through elliptical holes <NUM> of elliptical hole washers <NUM>. Fiber <NUM> also traverses elliptical hole <NUM> at proximal end <NUM>, extends beyond proximal end <NUM> and is attached to a proximal constraint assembly <NUM>. Proximal constraint assembly <NUM> will be described in greater detail below.

Also extending through lumen <NUM> is primary shape wire <NUM>. Each end of primary shape wire <NUM> extends through an elliptical hole washer <NUM>, via apertures <NUM>. Further, each end of primary shape wire <NUM> is optionally flattened or affixed to a broadened element <NUM> to prevent primary shape wire <NUM> from passing back through apertures <NUM>. Primary shape wire <NUM> is most advantageously constructed from Nitinol. Primary shape wire <NUM> is shape set to confer a secondary shape on embolic implant <NUM>. Coupled to primary shape wire <NUM> is distal support wire <NUM>. Distal support wire <NUM> is linked to shape wire <NUM> towards the distal end <NUM> of embolic implant <NUM>. In the example of <FIG>, distal support wire <NUM> is attached to shape wire <NUM> at bonds <NUM>. Where it is coupled to distal support wire <NUM>, the stiffness or robustness of shape wire <NUM> is augmented by distal support wire <NUM>, and both members confer the secondary configuration of embolic implant <NUM>. The absence of distal support wire <NUM> near proximal end <NUM> permits primary shape wire <NUM> to exhibit a softer, less robust secondary shape, and creates the progressively increasing softness of proximal end <NUM>.

Also disposed at each end of primary coil <NUM> are weld joints <NUM>. In the example of <FIG>, weld joints <NUM> are constructed of a Platinum-Platinum bond. Weld joints <NUM> each anchor elliptical hole washers <NUM> to primary coil <NUM>. After construction of weld joints <NUM>, atraumatic tips <NUM> are formed from a molded polymer or adhesive. Fiber <NUM> is also secured within atraumatic tips <NUM>. Atraumatic tip <NUM> disposed at distal end <NUM> also secures distal peg <NUM>, which will be described in greater detail below.

Turning for now to proximal end <NUM>, elliptical hole washer <NUM> prevents proximal constraint assembly <NUM> from entering lumen <NUM>. Proximal constraint assembly accordingly helps maintain tension on fiber <NUM>. Several structures define proximal constraint assembly <NUM>. These structures include fiber loop <NUM>, proximal constraint element or proximal constraint sphere <NUM>, adhesive <NUM>, and proximal wire <NUM>. Fiber loop <NUM> is threaded through a hole in proximal constraint sphere <NUM>. Proximal wire <NUM> is in turn threaded through the proximal end of loop <NUM>. Loop <NUM> thereby links proximal constraint sphere <NUM> and proximal wire <NUM>, and forms a mechanical lock of fiber <NUM> at proximal end <NUM>. Adhesive <NUM> is molded or applied to secure proximal wire <NUM>, loop <NUM>, and proximal constraint sphere <NUM>.

Returning now to distal end <NUM>, fiber <NUM> is threaded distally through embolic implant lumen <NUM> and then through aperture <NUM> of washer <NUM> disposed at distal end <NUM>. Fiber <NUM> is tied, knotted, or otherwise linked to distal peg <NUM>. Distal peg <NUM> can be formed from stainless steel, platinum, or other similarly rigid material. Distal peg <NUM> and fiber <NUM> are embedded or otherwise anchored or bonded to the distal atraumatic tip <NUM>, forming a mechanical lock adjacent to distal elliptical hole washer <NUM>. Together, proximal constraint assembly <NUM> and distal peg <NUM> maintain tension on fiber <NUM>, which thereby enables embolic implant <NUM> to resist stretching and elongation.

Turning now to <FIG>, an alternative embodiment according to the invention will be described. Embolic implant <NUM> is shown in its linear, delivery configuration. Following release from the constraints of a delivery catheter (not pictured), embolic implant will revert to a shape set secondary configuration. The secondary configuration may be any of a number of shapes according to the invention, including the complex shape illustrated in <FIG> above, and <FIG> described below.

Embolic implant <NUM> has a proximal end <NUM> and a distal end <NUM>. Elliptical hole washer 261is disposed at proximal end <NUM> and elliptical hole washer <NUM> is disposed at distal end <NUM>. Embolic implant <NUM> includes a primary coil <NUM> that is shape set during the manufacturing process to impart a secondary, deployed configuration on embolic implant <NUM>. Primary coil <NUM> surrounds lumen <NUM>. Disposed within lumen <NUM> is fiber <NUM>. In a fashion similar to that described in relation to <FIG>, fiber <NUM> extends through elliptical hole <NUM> of elliptical hole washer <NUM>, and through elliptical hole <NUM> of elliptical hole washer <NUM>. After passing through elliptical hole washer <NUM>, fiber <NUM> is looped back upon itself to form loop <NUM>, brought into lumen <NUM>, and knotted to itself to form knot <NUM>.

Also disposed within lumen <NUM> is distal support wire <NUM>. Distal support wire <NUM> renders the secondary configuration of embolic implant <NUM> more robust in the distal region in which distal support wire <NUM> lies. (Embolic implant <NUM> is more softly shaped near its proximal end <NUM>. ) Distal support wire <NUM> is attached to fiber <NUM> at bond <NUM>. Distal support wire <NUM> extends at its distal end through aperture <NUM> of elliptical hole washer <NUM>. The distal end of distal support wire <NUM> is optionally flattened to form a broadened element <NUM>, or attached to a broadened element <NUM>, to mechanically lock distal support wire <NUM> to elliptical hole washer <NUM>.

Weld joint <NUM> is constructed at proximal end <NUM> in a fashion similar to that described above, and atraumatic tip <NUM> is formed from reflowed or molded polymer, adhesive, or a combination thereof. Weld joint <NUM> anchors primary coil <NUM> and elliptical hole washer <NUM> at proximal end <NUM>. At distal end <NUM>, weld joint <NUM> similarly bonds primary coil <NUM> and elliptical hole washer <NUM>. A molded or reflowed polymer, adhesive or comparable material forms atraumatic tip <NUM>.

Proximal constraint assembly <NUM> is similar to the proximal constraint assembly described above in relation to <FIG>. Proximal constraint element or proximal constraint sphere <NUM> is linked to fiber <NUM> and proximal constraint wire <NUM>. Fiber <NUM> is either threaded through or wrapped around proximal constraint sphere <NUM> and looped, and proximal constraint wire <NUM> is threaded through loop <NUM>. Adhesive <NUM> secures proximal constraint sphere <NUM>, fiber <NUM> and proximal wire constraint wire <NUM>. Elliptical hole washer <NUM> prevents proximal constraint sphere <NUM> from entering lumen <NUM>, and prevents stretching and/or deformation of primary coil <NUM>. At distal end <NUM>, fiber <NUM> is tied or otherwise coupled to distal peg <NUM>, which is embedded in or otherwise bonded or anchored to distal atraumatic tip <NUM>, Securing fiber <NUM> to distal peg <NUM> helps maintain tension on fiber <NUM>.

As mentioned above, embolic implant <NUM> can be shape set to revert to a secondary configuration such as the configuration illustrated in <FIG> above. An advantageous step in shape setting implant <NUM> includes the step of shape setting primary coil <NUM>. Primary coil <NUM> is first formed by winding or otherwise forming continuous turns of a length of Platinum wire about a straight mandrel. The coiled wire can then be heat set to "remember" the primary coil shape. The Platinum primary coil formed from continuous turns can then be shaped around a fixture bearing a desired secondary shape. The Platinum primary coil is then heat set to "remember" the shape of the fixture. Of particular advantage in forming a low profile coil that readily fills empty space within an aneurysm or within a frame defined by another implant, is utilizing a fixture around which the primary coil turns are wrapped. In other words, the fixture is disposed within the lumen of the primary coil during the heat setting step, instead of the primary coil being first coiled, and then wrapped around the exterior of the fixture. Such a step results in smaller primary diameter coils and lower profile secondary configurations.

Turning now to <FIG>, an embodiment according to the invention will be described. While <FIG> above illustrates an example of a complex secondary shape of an implant according to the invention, <FIG> illustrates an alternative complex secondary shape, or secondary configuration of an embolic implant constructed according to the invention. <FIG> illustrates a plan, or topside view of implant <NUM> in its deployed configuration, outside a vessel of a subject, such as, for example, on a laboratory bench top. Similar to the embodiments described above, the embodiment illustrated in <FIG> also has a delivery configuration, similar to that illustrated in <FIG>, that is generally linear, that permits the device to be loaded into and delivered via a catheter or comparable delivery tool (not pictured). In its secondary configuration outside a vessel, implant <NUM> has a proximal segment <NUM>. Proximal segment <NUM> is shaped by a relatively soft or flexible shape wire (not visible in <FIG>). The shape wire imparting the secondary shape to proximal segment <NUM> is soft or flexible either because of a small diameter, a fine grind, or other processing step which produces a relatively soft filament. A wide range of flexibility, or softness, of the filament is within the scope of the invention, and the term "relatively" is used here to mean in comparison to distal segment <NUM>, which will be discussed below.

Proximal segment <NUM> has a secondary (or deployed) configuration, outside of a vessel that is helical. Alternatively, a proximal segment may have a secondary configuration that is complex, similar to the secondary configuration of distal segment <NUM>, described in more detail below. In yet another alternative embodiment, a proximal segment according to the invention may have a straight or linear configuration. Though a wide range of outer diameters of the helix of proximal segment <NUM> are within the scope of the invention, in the example illustrated here, the outer diameter of proximal segment <NUM> is approximately <NUM>-<NUM>. In a preferable embodiment, the outer diameter of proximal segment <NUM> is less than the outer diameter of distal segment <NUM>, when both proximal segment <NUM> and distal segment <NUM> are in their secondary configurations. Techniques for forming the secondary configuration of proximal segment <NUM> are known in the art, and include, for example, wrapping the shape wire disposed within proximal segment <NUM> around a mandrel and heat treating the segment so that it will return via shape memory behavior to the helical shape. Alternative techniques for achieving the shape memory objective are within the scope of the disclosure.

Implant <NUM> also has a distal segment <NUM>, as mentioned above. Distal segment <NUM> also includes, disposed within its interior and therefore not visible in <FIG>, a shape wire that is fabricated from a wire, filament, or comparable structure that is stiffer relative to that used to fabricate proximal segment <NUM>. (Alternatively, a coil may be shape set to return to the configuration of <FIG> upon release from a constraint. ) The shape of distal segment <NUM> may be formed from a wire or filament that is of greater thickness than that used to fabricate proximal segment <NUM>, in a fashion similar to that described in relation to <FIG> above. As another example, distal segment <NUM> may include, similar to that pictured in <FIG> above, a support wire coupled to the shape wire, the support wire extending only the length of distal segment <NUM>. As yet another example, additional processing steps such as annealing or other steps may be undertaken with respect to the material used to fabricate the filament that forms the support wire of distal segment <NUM>. Regardless of the technique used to manufacture the shape wire of distal segment <NUM>, the resulting secondary structure is a stiffer or more robust three dimensional object than that of proximal segment <NUM>.

In addition, as can be viewed in <FIG>, distal segment <NUM> has a secondary configuration that is more complex than the generally helical shape of proximal segment <NUM>. In an alternative embodiment according to the invention, a distal segment may have a secondary configuration that is helical, similar to the secondary configuration described in more detail above, in relation to the description of proximal segment <NUM>. In the example illustrated in <FIG>, the deployed shape of distal segment <NUM> is characterized as having sides <NUM>, top <NUM>, and bottom <NUM>. Taken together, sides <NUM>, top <NUM>, and bottom <NUM> generally define a cubic shape having rounded corners. Therefore, distal segment <NUM> can be described as having the shape of a cube. The term "cube" is used here to denote a three dimensional shape having several faces, and a particular embodiment according to the invention may or may not have six faces. The corners and edges of each face may be squared or rounded, curved or straight. Each face may or may not be of equal dimensions as each other face. Further, as is visible in <FIG>, the secondary shape of distal segment <NUM> frames some open "interior" space, and much of the coiled element defines the outer edges of the secondary shape of distal segment <NUM>.

In addition to having a very different secondary shape than proximal segment <NUM>, distal segment <NUM> also has a larger outside profile or outer diameter than proximal segment <NUM>. For example, in the embodiment illustrated in <FIG>, distal segment <NUM> has an outer diameter of approximately <NUM>-<NUM>. Techniques for shaping distal segment <NUM> include a series of steps of wrapping the stretch resistant member of distal segment <NUM> around a specialized mandrel or comparable tool, and heat treating the distal wire member so that it returns to the secondary shape imparted by the tool. Alternative techniques for fabricating the stretch resistant member disposed within distal segment <NUM> are within the scope of the disclosure.

The combination of both this larger outer diameter, the concentration of material at the outer edges of the shape, and the stiffer internal wire of distal segment <NUM> cause distal segment <NUM> to function much like an "anchor" for implant <NUM> within a vessel. In other words, distal segment <NUM> exerts some outward radial force against a vessel wall when implant <NUM> is deployed within a vessel. And, when deployed within a blood vessel of a subject, blood flow may carry proximal segment into the "interior" or distal segment <NUM>, filling distal segment <NUM>, and effectively preventing further blood flow through implant <NUM>. In this respect, implant <NUM> effectively has an "anchor" segment and a "filler" segment, resulting in a soft, well packed embolic implant.

Turning now to <FIG>, yet another alternative embodiment according to the invention will be described. Embolic implant <NUM> shares many of the same features of the embolic implant illustrated in <FIG>. Embolic implant <NUM> exhibits many advantages over prior art implants, including softness that enhances safety. Embolic implant <NUM> in particular boasts the feature of progressively increasing softness from its distal end <NUM> to its proximal end <NUM>. In other words, distal end <NUM> exhibits a more structured secondary or three dimensional shape than proximal end <NUM>. And proximal end <NUM> exhibits greater overall compliance and softness. An implant such as embolic implant <NUM> can be shape set to, upon release from the constraints of a delivery catheter, return to a secondary shape such as, for example, the configuration illustrated in <FIG> above.

Embolic implant <NUM> is shown in cross section in <FIG>, in order that its features may be readily viewed. Embolic implant <NUM> has a primary diameter of approximately <NUM> inches (<NUM>). Embolic implant includes primary coil <NUM>. Primary coil may be constructed from any of the materials suitable for coils described above. Primary coil <NUM> includes an internal lumen <NUM>. Primary coil <NUM> is shape set to exhibit a secondary shape following release from a delivery catheter (not pictured). Primary coil <NUM> may be constructed from Platinum or other suitable shape memory material. Extending through lumen <NUM> is fiber <NUM>. Fiber <NUM> also extends beyond proximal end <NUM> and is attached to a proximal constraint assembly <NUM>. Proximal constraint assembly <NUM> will be described in greater detail below. Also extending through lumen <NUM> is primary shape wire <NUM>. Primary shape wire <NUM> is most advantageously constructed from Nitinol. Coupled to primary shape wire <NUM> is distal support wire <NUM>. Distal support wire <NUM> is linked to primary shape wire <NUM> towards the distal end <NUM> of embolic implant <NUM>. The stiffness of shape wire <NUM> is augmented by distal support wire <NUM>, and both members confer the secondary configuration on embolic implant <NUM>. The absence of distal support wire <NUM> at proximal end <NUM> creates the progressive softness of proximal end <NUM>. In the example of <FIG>, distal support wire <NUM> is bonded to primary shape wire <NUM> at bonds <NUM>.

As mentioned above, primary shape wire <NUM> extends essentially the length of embolic implant <NUM>. Each end of shape wire <NUM> extends through an elliptical hole washer <NUM>, via apertures <NUM>. Elliptical hole washers <NUM> are disposed at each end of primary coil <NUM>. Also disposed at each end of primary coil <NUM> is a molded polymer or adhesive <NUM>, each of which secures elliptical hole washers <NUM> to primary coil <NUM> and fiber <NUM>, and forms atraumatic tips <NUM>. Both proximal end <NUM> and distal end <NUM> have atraumatic tips <NUM>.

Several structures define proximal constraint assembly <NUM>. As mentioned above, fiber <NUM> extends beyond proximal end <NUM>. Fiber <NUM> is looped back onto itself to form loop <NUM>. After forming loop <NUM>, fiber <NUM> extends back into lumen <NUM>, and is secured to itself via knot <NUM>. Loop <NUM> links proximal constraint sphere <NUM> and proximal wire <NUM>. Adhesive <NUM> is molded or applied to secure proximal wire <NUM>, loop <NUM>, and proximal constraint sphere <NUM>. Elliptical hole washer <NUM> and adhesive <NUM> prevent proximal constraint sphere <NUM> from entering lumen <NUM>.

Extending distally through lumen <NUM>, fiber <NUM> is tied, knotted, or otherwise linked to distal peg <NUM>. Distal peg <NUM> and fiber <NUM> are embedded or otherwise anchored to the distal atraumatic tip <NUM>. Together, proximal constraint assembly <NUM> and distal peg <NUM> maintain tension on fiber <NUM>, which thereby enables embolic implant <NUM> to resist stretching and plastic deformation.

Unlike the embodiment of <FIG>, embolic implant <NUM> also includes jacket <NUM>. Jacket <NUM> wraps or encases primary coil <NUM>. Jacket <NUM> is preferably constructed from a thrombogenic material such as polyester, polypropylene, silk, or other suitable material. The thrombogenic material or materials may be monofilament or multi-filament fibers. Jacket <NUM> may be constructed by wrapping, winding, braiding, threading or otherwise arranging the fiber or fibers in engagement with coil <NUM>. Jacket <NUM> may be constructed to form a "sleeve" like structure that is placed over coil <NUM>, or applied directly to coil <NUM> to form jacket <NUM>.

Claim 1:
An embolic implant comprising:
a proximal end (<NUM>) and a distal end (<NUM>);
a primary coil (<NUM>) configured to occlude blood flow in an implanted state, the primary coil defining a lumen (<NUM>);
a proximal constraint assembly (<NUM>) disposed at the proximal end; and
a distal constraint assembly (<NUM>) disposed at the distal end;
a stretch resistant fiber (<NUM>) disposed in the lumen and coupled to the proximal constraint assembly and the distal constraint assembly to prevent elongation of the primary coil; and
a shape memory filament (<NUM>) extending through the lumen, wherein the shape memory filament comprises a delivery configuration and a secondary configuration that imparts a complex shape on the embolic implant.