Patent Description:
Implantable intravascular devices are commonly used in endovascular procedures or treatments of various vascular ailments, for example, brain aneurysms. A catheter is inserted into the femoral artery in patient's leg and guided by imaging navigated through the vessel to the target site in the brain where the aneurysm is located. With the distal end of the catheter properly positioned on a proximal side of the aneurysm, a microcatheter is tracked through the catheter to the proximal side of the aneurysm. A delivery and deployment system loaded with an implantable intravascular device (e.g., embolic coil) is introduced via the microcatheter to the target site. During delivery to the target site, the implantable intravascular device is mechanically secured within the delivery system, typically via a wire (e.g., securement wire or pull wire). When properly positioned at the target site (e.g., at the location of the aneurysm) the wire is severed releasing the implantable intravascular device (e.g., embolic coil) to be deposited within the aneurysm. Severing of the embolic coil from the securement wire is typically achieved by passing of a small electrical current through the wire. This process is repeated until the area of the vessel with the weakened wall is tightly packed with numerous embolic coils occluding blow flow thereto thereby preventing rupture.

During delivery of an implantable intravascular device to a target site within the artery or vessel, conventional delivery and detachment systems are designed such that no friction force is intentionally imposed on the securement wire extending therethrough. It is the goal and intent of such conventional devices to avoid altogether imposing any friction force on the securement wire. An issue or drawback associated with such conventional friction-free configuration is that during delivery the securement wire is subject to unwanted shifting, movement, or translation resulting in potential imprecise delivery or detachment of the implantable intravascular device at the target site in the artery.

It is therefore desirable to develop an improved system for delivery and detachment of an implantable intravascular device that intentionally introduces a controlled amount of friction force on the securement wire to minimize or prevent unwanted shifting, movement, or translation during delivery of the implantable intravascular device to the target site in the artery. <CIT> provides a medical device system that may include an elongate shaft having a lumen extending from a proximal end to a distal end, a proximal release wire, and a distal release wire. The proximal release wire may extend distally from a proximal end configured to remain outside the body to a distal end and may be slidably disposed within the lumen of the elongate shaft. The distal release wire may extend distally from a proximal end to a distal end and may be slidably disposed within the lumen of the elongate shaft. The proximal end of the distal release wire may be slidably coupled to the distal end of the proximal release wire. The distal release wire may be configured to releasably attach a medical device to the distal end of the elongate shaft. <CIT> provides a medical device for placing an embolic device, such as an embolic coil, at a predetermined site within a vessel of the body including a delivery catheter and a flexible pusher member slidably disposed within the lumen of the catheter. An embolic device having a headpiece coupled to the proximal end is releasably disposed within the distal end of the pusher member and retained in place by a retractable fiber, having a coiled distal portion. When the embolic device is advanced to the predetermined site within the vessel, the detachment fiber is retracted from around the headpiece of the embolic device to thereby release the embolic device. <CIT> provides a braided coil catheter to delivery of a vascular implant through a catheter including a braided coil adapted to at least partially retain a vascular implant comprising a braided coil distal tip, a braided coil proximal end connected by a braided coil body having a lumen with a lumen diameter; a friction plug comprising a proximal friction plug end, a distal friction plug end connected by a friction plug body with a friction plug diameter greater than the lumen diameter to frictionally fit into the lumen of the braided coil distal tip; a vascular implant having an implant mating end, an implant non-mating end connected by an implant body wherein the implant mating end is connected to the distal friction plug end; and a pusher catheter inserted into the lumen and to contact the proximal friction plug end and force the friction plug from the lumen. <CIT> provides a detachable treatment device delivery system that includes a delivery sheath defining a lumen, a treatment device having a proximal attachment segment, which includes an enlarged outer diameter region, configured for receipt within the delivery sheath, and a deployment wire configured for receipt within the delivery sheath. A delivery configuration is defined by an overlap of a distal segment of the deployment wire and the enlarged outer diameter region within an attachment zone of the delivery sheath. The deployment wire and the treatment device have a combined outer diameter at the overlap, and, in the delivery configuration, the overlap is proximally spaced from a narrowed diameter region of the attachment zone, which has a smaller diameter than the combined outer diameter. In a deployed configuration, the deployment wire is proximally spaced from the attachment zone, and the proximal attachment segment is permitted to advance through the distal opening. <CIT> provides a device for delivering an occlusive element includes an elongate pusher member having a lumen. A locking member is disposed within the lumen of the elongate pusher member. A moveable elongate releasing member is disposed within the lumen of the elongate pusher member. A filament is secured to the distal end of the elongate releasing member. The occlusive member is locked to the elongate releasing member when the filament passes through a securing member on the occlusive member and is pinched or wedged between the locking member and the elongate releasing member. The occlusive element is in an unlocked state when the elongate releasing member is retracted proximally relative to the elongate pusher member. The filament, along with the elongate releasing member, are retracted proximally until the filament is detached or uncoupled from the securing member of the occlusive member. <CIT> provides a medical system for delivering and deploying a medical implant, and the method of using thereof. The medical system can have an implant with an engagement loop, and a delivery system having an engagement wire and an interface. During implant delivery, the engagement wire engages the engagement loop of the implant. The engagement wire further interacts with the interface in order to prevent unintended disengagement of the engagement loop from the engagement wire. Certain embodiment of the present teaching also includes an implant release control mechanism fixedly attaching to a proximal end of the engagement wire. During implant delivery, the implant release control mechanism attaches the proximal end of the delivery system. During implant deployment, the implant release control mechanism detaches the proximal end of the delivery system.

The present invention is directed to an improved system for delivery and detachment of an implantable intravascular device that intentionally introduces a controlled amount of friction force on the securement wire to minimize or prevent unwanted shifting, movement, or translation during delivery of the implantable intravascular device to the target site in the artery.

Another aspect of the present invention relates to a delivery and detachment system for an implantable intravascular device, in which the system includes an inner support tube having a passageway extending in an axial direction from a proximal end to an opposite distal end. The system further includes a securement wire extending through the passageway of the inner support tube. Imposed on the securement wire is a controlled friction force established within an intentional friction zone located anywhere between the distal end of the inner support tube and a midway point between the respective proximal and distal ends of the inner support tube.

Yet another aspect of the invention is directed to a method for manufacture of a delivery and detachment system for an implantable intravascular device, as described in the preceding paragraph. Initially, an inner support tube having a passageway extending in an axial direction from a proximal end to an opposite distal end is provided. Then, a securement wire is threaded through the passageway of the inner support tube, imposing on the securement wire a controlled friction force established within an intentional friction zone located anywhere between the distal end of the inner support tube and a midway point between the respective proximal and distal ends of the inner support tube.

While still another aspect of the present invention relates to a method of using a delivery and detachment system for an implantable intravascular treatment device. The delivery and detachment system including an inner support tube having a passageway extending in an axial direction between a proximal end and an opposite distal end; and the delivery; and detachment system further including a securement wire extending through the passageway of the inner support tube; imposed on the securement wire is a controlled friction force established within an intentional friction zone located anywhere between the distal end of the inner support tube and a midway point between the respective proximal and distal ends of the inner support tube. The method of using the system being that during delivery of the implantable intravascular treatment device to a target site, the imposed controlled friction force minimizes movement of the securement wire relative to the inner support tube. Whereas, upon the implantable intravascular treatment device reaching the target site, a force is applied in a proximal direction on the securement wire sufficient to exceed the imparted controlled friction force and releasing the implantable intravascular device from the delivery and detachment system.

The foregoing and other features of the present invention will be more readily apparent from the following detailed description and drawings illustrative of the invention wherein like reference numbers refer to similar elements throughout the several views and in which:.

In the description, the terms "distal" or "proximal" are used in the following description with respect to a position or direction relative to the treating physician or medical interventionalist. "Distal" or "distally" are a position distant from or in a direction away from the physician or interventionalist. "Proximal" or "proximally" or "proximate" are a position near or in a direction toward the physician or medical interventionist. The terms "occlusion", "clot" or "blockage" are used interchangeably.

During an endovascular treatment procedure (e.g., coil embolization), it is desirable for the system to reliably deliver and detach/deploy/deposit/release the implantable intravascular device (e.g., embolic coil) at a precise location or target site (e.g., aneurysm) within a vessel or artery. The implantable intravascular device (e.g., embolic coil) is releasably loaded on (e.g., secured to) the distal end of a delivery and detachment system that together as a unit are advanced to the desired target site in the vessel or artery. Releasable securement of the implantable intravascular device is via a securement wire (e.g., pull-wire) extending axially in a proximal direction through the delivery and detachment system. When the implantable intravascular device is precisely located at the target site in the artery or vessel the interventionalist applies sufficient force in a proximal direction on the securement wire to release (e.g., disengage) the implantable intravascular device for deposit at that location within the artery. Any shifting, translation, or movement of the securement wire during delivery of the implantable intravascular device may result in imprecise positioning and depositing offset from the intended target site in the artery or vessel.

The present inventive delivery system minimizes or prevents unwanted translation, shifting, or movement of the securement wire during delivery of the implantable intravascular device to the target site in the artery by intentionally introducing or imposing a controlled friction force on the securement wire within an intentional friction zone.

<FIG> is a longitudinal/axial cross-sectional view of an exemplary assembled delivery and detachment system <NUM> in accordance with the present invention with an implantable intravascular device (e.g., embolic coil) <NUM> loaded thereto. Delivery and detachment system <NUM> has a proximal end <NUM> and an opposite distal end <NUM> to which the implantable intravascular device (e.g., embolic coil) <NUM> is releasably secured thereto. System <NUM> includes a main or outer delivery tube <NUM> having a channel <NUM> extending in a longitudinal/axial direction therethrough. Insertable into the distal end of the channel <NUM> of the main delivery tube <NUM> is a proximal end of an inner support tube <NUM> which itself has a passageway <NUM> defined therethrough in a longitudinal/axial direction. A coil <NUM> (e.g., a helical coil) is disposed radially outward of the outer surface of the inner support tube <NUM>. An outer sleeve <NUM>, made of a lubricious reflowable material or a reflowable material having a lubricious outer coating, covers the outer surface of the coil <NUM>. By way of example, the outer sleeve is a thermoplastic elastomer (TPE) such as a polyether block amide (PEBA) known under the tradename of PEBAX®. In a preferred embodiment, at the distal end <NUM> of the delivery and detachment system <NUM> is disposed a compressible component (e.g., a helical detachment coil) <NUM> having an outer diameter larger than the coil body <NUM>, wherein the outer sleeve <NUM> stops proximally of (does not extend in an axial direction over or cover any portion of the compressible component <NUM>). Similarly, the inner support tube <NUM> terminates proximally (i.e., does not extend into the cavity) of the compressible component <NUM>.

An implantable intravascular device (e.g., embolic coil) <NUM> is releasably connected to the distal end <NUM> of the delivery and detachment system <NUM> via a loop wire <NUM> threaded through an engagement device (e.g., proximal key) <NUM> disposed between the distal end of the compressible component <NUM> and the proximal end of the implantable intravascular device <NUM>. Respective free proximal ends of the loop wire <NUM> are permanently affixed to an inner surface of the compressible component <NUM>, whereas an opposite distal end of loop wire <NUM> forms a closed loop. Engagement component (e.g., proximal key) <NUM> has an opening. As such, the implantable intravascular device <NUM> is releasably attached, connected, or secured to the distal end <NUM> of the delivery and detachment system <NUM> by bending a portion of the closed loop distal end of the loop wire <NUM> upwards (e.g., perpendicularly to the axial direction of the delivery and detachment system) through the opening of the engagement component <NUM> and threading the distal end of the securement wire (e.g., pull wire) <NUM> in a distal direction through the bent upwards closed loop distal end of the loop wire <NUM>. Securement wire <NUM> is depicted as straight (i.e., extending or moving uniformly in one direction only; without a curve, kink, or bend); however, a non-straight, curved, kinked, or bent securement wire is possible to impart an even greater friction force. Engagement of the distal end of the securement wire <NUM> within the closed loop distal end of the loop wire <NUM> secures the engagement component (e.g., proximal key) <NUM> and implantable intravascular device (e.g., embolic coil) <NUM> attached distally thereto to the distal end of the delivery and detachment system <NUM>.

The implantable intravascular device <NUM> is deployed, released, or deposited at a target stie in the artery by subjecting the securement wire <NUM> to an axial force in a proximal direction (e.g., pulling in a proximal direction). Sufficient axial force is applied in the proximal direction so that the distal end of the securement wire <NUM> is disengaged (i.e., free from, clear of, or no longer constrained by) the loop wire <NUM>. Now released from the loop wire <NUM>, the securement wire <NUM> is no longer connected to the engagement component (e.g., proximal key) <NUM> or implantable intravascular device <NUM> attached thereto.

Compressible component <NUM> may initially be under compression subject to decompression/expansion once the securement wire <NUM> is disengaged from the loop wire <NUM> imparting a force in a distal direction on the proximal end of the implantable intravascular device (e.g., embolic coil) <NUM>. The loop wire <NUM> preferably has sufficient flexibility such that when the decompression/expansion force is imparted by the compressible component <NUM> the loop wire <NUM> moves out of the opening of the engagement component (e.g., proximal key) <NUM> thereby detaching/releasing the implantable intravascular device <NUM> from the delivery system <NUM>. Moreover, the force imparted by the compressible component <NUM> during decompression/expansion preferably pushes the implantable intravascular device <NUM> in a distal direction away from the distal end <NUM> of the delivery system <NUM> creating a predetermined separation distance therebetween upon deployment. Other purely mechanical (non-thermal and non-electrical) arrangements releasable upon application of an axial force in a proximal direction (e.g., pulling force) are contemplated and within the intended scope of the present invention for releasably securing the implantable intravascular device to the distal end of the delivery and detachment system.

A stretch resistant element <NUM> is preferably disposed internally within the cavity of the implantable intravascular device <NUM>. At a distal end, stretch resistant element <NUM> is secured via a bead or other stopping component <NUM> having an outer diameter that prevents passage in a proximal direction into the interior cavity of the implantable intravascular device <NUM>, while its opposite proximal end is secured to the distal end of the engagement component <NUM> (e.g., threaded through an opening thereof).

For trackability during use one or more marker bands detectable through imaging may be provided along regions of one or more components of the delivery and detachment system. For instance, marker bands 195a, 195b (e.g., a fluor-saver marker) may be disposed along an outer surface of a proximal section of the main delivery tube <NUM> and a distal section of the coil body <NUM> (preferably aligned with that of the side port openings 165a, 165b, 165c created in the inner support tube <NUM>). The arrangement, number, and use altogether of marker bands is optional.

In preparation of assembly of the components of the present inventive delivery and detachment system <NUM>, along a distal section of the inner support tube <NUM> a plurality of radially inward cuts are made extending from the outer surface through to (intersecting) the passageway <NUM> creating a plurality of side port openings <NUM> that allow a fluid (e.g., the reflowable material of the outer sleeve) to flow/seep therethrough. The term "distal section" is expressly defined as any section, region, portion, or area along the inner support tube that satisfies the following conditions: (i) in a distal direction relative to a midpoint between opposing proximal and distal ends/tips of the inner support tube; and (ii) in a proximal direction relative to the distal end/tip of the inner support tube. In other words, the selected distal section along which the intentional friction zone is created is located anywhere in a region between, without including either, the distal end/tip and the midpoint of the inner support tube.

<FIG> is a perspective view of an exemplary supporting and cutting structure <NUM> used to make radially inward skived cuts into an outer surface of the inner support tube <NUM> through to (intersecting) the passageway <NUM> defined axially therein. The inner support tube <NUM> in which the side openings are to be created is supported on the structure <NUM> and held in position by a clamp <NUM> (<FIG> & <FIG>).

A side port template <NUM> having a plurality of troughs (305a, 305b, 305c) arranged parallel to one another in an X-direction define the location, spacing, arrangement and the angle of the cuts to be made to the inner support tube <NUM> to create the side port openings <NUM> having a desired geometric cross-sectional shape (e.g., trapezoidal shape). Three troughs (305a, 305b, 305c) are shown in the example represented in <FIG> & <FIG> all having the same cross-sectional shape (e.g., trapezoidal shape); however, the number, location, spacing, arrangement, and/or cross-sectional shape of each trough may be designed, as desired.

By way of example, adjacent side port openings defined in the inner support tube <NUM> depicted in <FIG> are separated from one another both in a longitudinal/axial direction and in a radial direction. That is, side port 165a is separated both in a longitudinal/axial direction and a radial direction (approximately <NUM>°) relative to that of adjacent side port 165b, as is true for all adjacent side port openings illustrated. Three side port openings 165a-165c are illustrated in <FIG>; however, any number of two or more side port openings may be made, as desired. The geometric shape of each side port opening may be modified, as desired, so long as each side port opening extends radially inward through the inner support tube <NUM> (i.e., from its outer surface to its passageway <NUM>). A controlled amount of intentionally introduced friction force imposed on the securement wire <NUM> when threaded through the passageway <NUM> is produced by selecting: (i) the number of side port openings; (ii) the location and arrangement of the side port openings (both longitudinally/axially and radially); and (iii) the dimensions in an axial direction (Z-direction) and in a radial direction (X-direction) of each side port opening created in the inner support tube.

In the exemplary configuration of <FIG>, each side port opening of the inner support tube has an axial length of approximately <NUM>, with at least approximately <NUM> separation in an axial direction between adjacent side port openings. Continuing with this example, at a minimum there would be approximately <NUM> distance in an axial direction from the proximal end of the first side port opening and the proximal end of the adjacent/next second side port opening. The spacing of cuts in a radial direction may be more compact depending on such factors as the depth (radially inward) of the cut and amount of remaining material (i.e., strength) of the inner support tube. Referring to <FIG> varying exemplary depth cuts are made to the inner support tube. Specifically, <FIG> depict a longitudinal cut-away view and a bottom portion end view, respectively, of the inner support tube <NUM> having a side port opening <NUM> with a <NUM>% depth (radially inward) cut, whereas <FIG> depict the same views for a side port opening with a <NUM>% depth (radially inward) cut. The deeper radial cut (<NUM>% depth) extending further radially inward into the clearance or free space within the passageway <NUM> of the inner support tube <NUM> when a smaller diameter protective metal wire/mandrel <NUM> is used.

Prior to assembling the delivery and detachment system, the inner support tube is mechanically supported (held in place) on a supporting and cutting structure while the plurality of radially inward cuts are made to create the side port openings along the distal section thereof. <FIG> & <FIG> depict an exemplary supporting and cutting device <NUM> including a substrate <NUM> and a corrugated/wave platform <NUM> having a plurality of longitudinally arranged parallel ridges and valleys <NUM> extending along the Z-axis. The inner support tube <NUM> in which the side port openings are to be created is placed within an associated one of the valleys (between adjacent ridges) <NUM> of the corrugated/wave platform <NUM> so that the longitudinal axis of the inner support tube <NUM> is arranged parallel with the Z-axis. Side port openings in more than one inner support tube may be cut simultaneously at the same time, wherein each inner support tube <NUM> is placed within an associated valley <NUM> on the corrugated/wave platform <NUM> of the supporting and cutting device <NUM>. Supporting and cutting device <NUM> further includes a side port template <NUM> having defined therein parallel to the Z-axis a series of channels <NUM> equal in number to that of the valleys <NUM> of the corrugated/wave platform <NUM>. Each channel <NUM> of the side port template <NUM> is aligned in a Z-direction with a corresponding valley <NUM> of the corrugated/wave platform <NUM>.

Side port template <NUM> has a plurality of troughs (e.g., recesses) 305a-305c defined therein parallel to one another and extending along an X-axis perpendicular to the Z-axis. The number of troughs 305a-305c corresponds to the desired number of side port openings to be created in the inner support tube. Each trough 305a, 305b, 305c preferably, but need not necessarily, has the same cross-section parallel to the Z-axis. The channels <NUM> defined in the side port template <NUM> parallel with the Z-axis emerge on one side, extend across, and thereafter continue on the opposite side of each of the plurality of troughs 305a-305c. Each trough preferably has a trapezoidal like cross-sectional shape parallel to the Z-axis (i.e., tapered sides widening in opposing directions from a flat bottom surface) connecting the narrowing free ends of the tapered sides), as shown in <FIG>. The preferred range of angularity of the tapered sides of the notch is an acute angle α (e.g., less than <NUM>°) relative to the Z-axis extending perpendicularly through the channel <NUM>.

Initially, the inner support tube <NUM> in which the side port openings are to be created is placed/supported within one of the valleys <NUM> of the corrugated/wave shape platform <NUM> and slid along the Z-direction into an associated channel <NUM> defined through the side port template <NUM> (<FIG>). With continued advancement in the Z-direction upon encountering each trough 305a the distal end of the inner support tube <NUM> emerges/exits from the channel <NUM>, advances across the associated trough, and once again is received in the channel that picks up on the opposite side of the trough. After advancing across the final or last trough, the distal end of the inner support tube is preferably threaded/received once again in the channel at the opposite side of the final/last trough to ensure that the distal most end of the inner support tube is supported/held within the channel while the side port openings are being cut.

Once fully inserted into a corresponding channel <NUM> of the side port template <NUM>, the inner support tube <NUM> is held in position on the supporting and cutting device <NUM> via a clamp <NUM>. With the inner support tube <NUM> secured in place on the supporting and cutting device <NUM>, a protective wire <NUM> made of metal or some other material impenetrable by the blade is threaded through the passageway <NUM> preventing piercing/penetrating of the blade through to the opposing side (<NUM>° opposite side) of the inner support tube when making the skived cuts. <FIG> is an enlarged view of the inner support tube <NUM> extending across the trapezoidal trough 305a of the side port template <NUM> depicting the protective wire <NUM> as it is being advanced in a distal direction through the passageway <NUM> thereof.

A blade <NUM> (e.g., razor blade) is receivable within an opening in a hinged mounting arm <NUM> the angle of which may be adjusted, as desired, via a rotating handle <NUM>. Preferably, the blade <NUM> is secured in place using a conventional locking mechanism (e.g., tightening thumb screw) at an acute angle α (less than <NUM>° relative to the Z-axis), substantially conforming to the angle of the tapered sides of the trapezoidal trough. Each side port opening <NUM> is preferably made by two passes/cuts of the blade using the exemplary supporting and cutting device of <FIG>, insufficient reflow of the material reaching the passageway of the inner support tube to create the intended friction zone being achieved if only a single cut (slit) was made. A first pass/cut within one of the troughs is made with the blade <NUM> oriented at an acute angle α (less than <NUM>° relative to the Z-axis), as shown in <FIG>, for each location of the side port opening. Thereafter, the rotating handle <NUM> is adjusted <NUM>° (flipped horizontally) (as shown in <FIG>) at which position the second pass/cut is made with the blade to complete that particular side port opening. With the second pass/cut of the blade a piece (wedge) of the inner support tube bounded on either side by the respective passes/cuts is lifted or removed revealing the side port formed therein (and the now visible passageway). This process is repeated for each of the plurality of side ports desired in the distal section of the inner support tube. Referring to <FIG>, troughs 305a, 305c may be used to create side port openings 165a, 165c, respectively, while side port opening 165b may be created using trough 305b (after rotating the inner support tube <NUM> by <NUM>°). Trapezoidal shape side cuts are preferred over a perpendicular cut relative to the X-axis to ensure that the size of the side port opening is sufficient to allow sufficient material to reflow/seep therethrough and into the passageway.

Using a blade (e.g., a razor blade, knife, or other cutting device) <NUM> a plurality of radially inward cuts, preferably skived cuts, are made along the distal section or region of the inner support tube <NUM> to create the side port openings 165a-165c. Each radially inward skived cut removes a portion of the outer surface of the inner support tube <NUM> through to the longitudinal/axial passageway <NUM> extending from its proximal end/tip to its opposite distal end/tip.

The number of side port openings and width (along the Z-axis) of each side port opening may be modified, as desired. Each side port opening may have a uniform shape and size or vary, as desired. Inner support tube <NUM> prevents or minimizes stretch resistance of the securement wire <NUM> within the delivery system <NUM>. Thus, the shape and size of the side port opening is selected with several competing considerations in mind. On the one hand, the side port opening is sufficient in size to allow reflow/seepage of the reflowable outer sleeve material and creation of a controlled amount of friction force on the securement wire. While, on the other hand, the wider the side port opening the weaker the ability of the inner support tube to provide such resistance.

The present inventive inner support tube has been shown and described as having a plurality of side port openings defined therein with each side port opening being formed from two skived cuts. The angle of the single cut may be at any desired angle α in a range of <NUM>° (relative to the Y-axis) ≥ α ><NUM>° (<FIG>).

With the desired number of side port openings created, following withdraw of the protective wire <NUM> from the passageway <NUM> (as illustrated in <FIG>), the inner support tube <NUM> comprising part of the present inventive delivery and detachment system is ready to be assembled. Specifically, the inner support tube <NUM> with the side port openings 165a, 165b, 165c defined in a distal section or region thereof is inserted into the interior cylindrical shape cavity formed by the coil <NUM>. No portion of the inner support tube <NUM> extends in a longitudinal direction into the inner cavity of the compressible element <NUM>, i.e., each of the side port openings <NUM> are disposed proximally of and separated a predetermined distance relative to the compressible element <NUM>. The outer sleeve or covering <NUM> is positioned about or covering the outer surface of the coil <NUM>. For illustrative purposes only, the inner support sleeve <NUM> is first inserted into the coil <NUM> which together as a unit are received within the outer sleeve <NUM>. It is, however, also within the intended scope of the present invention to insert the coil <NUM> within the outer sleeve <NUM> to form a unit together and thereafter insert the inner support tube <NUM> into the inner cavity formed by the coil <NUM> that forms a unit with the outer sleeve <NUM>. Thus, the order of assembly of these three components (e.g., the inner support tube <NUM> (with the side port openings defined in the distal section or region thereof); the coil <NUM>; and the outer sleeve <NUM>) may be selected, as desired, and is within the intended scope of the prevent invention.

A straight mandrel is inserted in a longitudinal direction through the passageway of the inner support tube <NUM> after being assembled together with the coil <NUM> and outer sleeve <NUM>. The straight mandrel is heated to a prescribed fusing temperature to cause the outer sleeve <NUM> material (e.g., polyether block amide (PEBA) or other thermoplastic polymer) to reflow over the outer surface of the inner support tube <NUM> (made of a thermoplastic polymer material that does not melt at that temperature such as polyether ether ketone (PEEK)), radially inward through the side port openings 165a-165c, and partially into (along the inner wall of) the passageway <NUM>. Thus, in the areas where the outer sleeve material seeps into the passageway the inner diameter of the passageway of the inner support tube is reduced. The dimensions of the side port openings 165a-165c are selected to allow sufficient reflow of the material of the outer sleeve <NUM> to seep into the passageway <NUM> of the inner support tube <NUM> and create a controlled amount of friction force when directly physically contacting or directly engaging with the securement wire <NUM> threaded therethrough. By way of illustrative example, the preferred range of outer diameter of the mandrel is in a range of approximately <NUM>% - approximately <NUM>% of the inner diameter of the passageway of the inner support tube. In experimental testing, the outer diameter of the mandrel is <NUM> (<NUM> in. ) creating an intentional friction zone within a range of approximately <NUM> gF to approximately <NUM> gF to maintain the position of the securement wire in the delivery and detachment system during use.

In addition to the friction force resulting from the reduced or decreased inner diameter of the passageway <NUM> of the inner support tube <NUM> created by the reflow of the outer sleeve material through the side port openings into the passageway, an additional contribution to the friction force imposed on the securement wire <NUM> may be produced by the frictional characteristics of the reflow material itself of the outer sleeve upon contacting with the outer surface of the mandrel. In this regard, the mandrel used to reflow the outer sleeve material through the side port openings created in the inner support tube may be either coated (i.e., a mandrel coated with a lubricious coating) or non-coated (i.e., a mandrel not coated with a lubricious coating). In the case of a non-coated (free of any lubricious coating) mandrel the reflowed outer sleeve material adheres along the entire outer surface of the mandrel providing a predetermined amount of tacking force desirably contributing to the controlled friction force imposed on the outer surface of the securement wire. Even when using a mandrel coated with a lubricious material (e.g., Polytetrafluoroethylene (PTFE)), portions, sections, or regions of the outer surface of the mandrel exposed or lacking the coating will nevertheless exist producing patches in which a tacking force is produced. In the case of the coated mandrel, the tacking force is generated only in those random areas where the coating happens to be omitted, missing, or not present on the outer surface of the mandrel, whereas the tacking force produced when employing a non-coated mandrel extends substantially over the entire outer surface of the mandrel.

After the prescribed exposure time to the heat temperature has expired (for example, <NUM> (<NUM>°F) for a period of <NUM> sec. - <NUM> sec. ) withdraw of the mandrel from the three-component assembly (outer sleeve <NUM>, coil <NUM>; and inner support tube <NUM>) allows cooling and hardening of the material of the outer sleeve <NUM> that has seeped through the side port openings into the passageway <NUM> of the inner support tube <NUM>. Next, the securement wire <NUM> secured at its distal end to a distal assembly comprising the detachment coil <NUM>, proximal key <NUM> and implantable intravascular device <NUM> is threaded in a proximal direction through the passageway <NUM> of the three-component assembly (reflowed outer sleeve <NUM>, coil <NUM>, and inner support tube <NUM>).

A main delivery tube <NUM> having a channel <NUM> defined in a longitudinal/axial direction therethrough is assembled to the proximal end of the thus assembled delivery and detachment system. Specifically, the proximal end of the inner support tube <NUM> extends in a proximal direction beyond the proximal end of the of the coil <NUM> and is sized to be telescopically receivable in the channel <NUM> of the main delivery tube <NUM>. The threading of the securement wire <NUM> continues in a proximal direction through the channel <NUM> of the main delivery tube <NUM> and a lumen <NUM> of a proximal inner tube <NUM> whose distal end is received within the channel <NUM>. A portion of the proximal end of the proximal inner tube <NUM> extends in a proximal direction relative to the proximal end of the main delivery tube <NUM>. The proximal end of the securement wire that has been threaded in a proximal direction rough the lumen <NUM> of the proximal inner tube <NUM> and the channel <NUM> of the main delivery tube <NUM> is non-releasably secured (e.g., welded) <NUM> to the proximal end of the proximal inner tube <NUM>.

In use, a catheter or microcatheter is navigated through the artery to the proximal side of the target site (e.g., aneurysm). Thereafter, using the assembled delivery and detachment system (as shown in <FIG>) the implantable intravascular device <NUM> releasably secured to the distal end thereof is advanced through the catheter or microcatheter to the target site. During delivery of the implantable intravascular device <NUM> by the interventionalist (prior to deployment) undesirable shifting, movement or translation of the securement wire is prevented or minimized by intentionally imposing a controlled friction force on a radially outward surface along a distal section of the securement wire <NUM> where it directly physically contacts the reflowed material of the outer sleeve <NUM> that has seeped through the side port openings <NUM> of the inner support tube <NUM> and into the passageway <NUM> thereof. The amount of friction force imposed is sufficient to prevent or minimize shifting, movement or translation of the securement wire in the passageway during delivery able to be overcome only by application of sufficient axial force in a proximal direction on the securement wire when deploying (releasing) the implantable intravascular device from the delivery and detachment system to be precisely and accurately deposited at the target site in the artery.

The design described above and illustrated narrows the inner diameter of the passageway defined in the inner support tube by reflow of the outer sleeve material through side port openings defined therein and into the passageway to intentionally narrow the inner diameter along those areas imposing a controlled friction force on the outer surface of the securement wire threaded therethrough. Other mechanical configurations to intentionally introduce a controlled friction force on the outer surface of the securement wire are contemplated and within the intended scope of the present invention. Rather than alter the structure of the inner support tube (e.g., creating the side port openings in and reducing the inner diameter of the passageway thereof) the design of the securement wire along a distal section thereof may be modified. In this regard, a bend or kink in the otherwise substantially linear may be made along a distal section of the securement wire to intentionally create one or more points/sections/areas/regions of direct physical contact between the securement wire <NUM> and the inner wall of the passageway <NUM> of the inner support tube <NUM>. For instance, the securement wire <NUM>' in <FIG> intentionally includes multiple bends or kinks configured as a trapezoidal shape establishing direct physical regions of contact of the securement wire with the inner wall of the passageway (approximately <NUM>° radially from one another) resulting in the imposition of an intentional controlled friction force. Alternative configurations in the bending or kinking of the securement wire forming a variety of geometric shapes are contemplated and within the intended scope of the present invention. The number of, overall surface area, and/or spacing between points/sections/areas/regions of forced or intentional direct physical contact between the securement wire and the inner wall of the lumen of the inner support tube may be selected, as desired, to achieve a controlled intentional friction force on the securement wire when assembled within the delivery and detachment system. Once again keeping in mind that, on the one hand, the intentional controlled friction force imposed by the bent or kinked securement wire directly engaging with the inner wall of the passageway of the inner support tube is sufficient to prevent or minimize shifting, translation or movement of the securement wire during delivery of the implantable intravascular device. Yet, on the other hand, upon application of sufficient force in a proximal direction on the securement wire <NUM> the intentional controlled friction force is overcome releasing the implantable intravascular device <NUM> from the delivery and detachment system.

Regardless of the particular mechanical design of the way in which the assembled delivery and detachment system creates an intentional friction zone, the controlled amount of friction force imposed on the securement wire when assembled in the delivery and detachment system may be modified, as desired, to prevent or minimize shifting, translation, or movement of the securement wire during delivery and detachment of the implantable intravascular device, yet able to be overcome when sufficient force is applied in a proximal direction on the securement wire to release the implantable intravascular device. The present invention has been shown and described with respect to a delivery and detachment system loaded with an embolic coil during a coil embolization procedure in the treatment of an intracranial aneurysm. It is contemplated and within the intended scope of the present invention to utilize the present inventive delivery and detachment system for other types of implantable intravascular devices used in other endovascular treatment procedures.

Thus, while there have been shown, described, and pointed out fundamental novel features of the invention as applied to a preferred embodiment thereof, it will be understood that various omissions, substitutions, and changes in the form and details of the systems/devices illustrated, and in their operation, may be made by those skilled in the art without departing from the scope of the appended claims.

Claim 1:
A delivery and detachment system (<NUM>) for an implantable intravascular device (<NUM>), the system comprising:
an inner support tube (<NUM>) having a passageway (<NUM>) extending in an axial direction from a proximal end to an opposite distal end; and
a securement wire (<NUM>) extending through the passageway of the inner support tube;
an outer sleeve (<NUM>) surrounding an outer surface of the inner support tube, wherein the outer sleeve is made of a reflowable material;
characterized in that the inner support tube has defined therein at least one side port opening (165a, 165b, 165c) intersecting with the passageway and the outer surface of the inner support tube; and the reflowable material of the outer sleeve being seepable through the at least one side port opening defined in the inner support tube and into the passageway of the inner support tube forming an associated point of direct physical contact with the securement wire; and
wherein each associated point of direct physical contact is configured to impose on the securement wire a controlled friction force established within an intentional friction zone located anywhere between the distal end of the inner support tube and a midway point between the respective proximal and distal ends of the inner support tube.