Patent Application
20150313702
1. Technical Field
This application relates to a vascular filter and more particularly to a method of inserting a vein filter into the vessel.
2. Background of Related Art
Passage of blood clots to the lungs is known as pulmonary embolism. These clots typically originate in the veins of the lower limbs and can migrate through the vascular system to the lungs where they can obstruct blood flow and therefore interfere with oxygenation of the blood. Pulmonary embolisms can also cause shock and even death.
In some instances, blood thinning medication, e.g. anticoagulants such as Heparin, or sodium warfarin can be given to the patient. These medications, however, have limited use since they may not be able to be administered to patients after surgery or stroke or given to patients with high risk of internal bleeding. Also, this medication approach is not always effective in preventing recurring blood clots.
To avoid invasive surgery, less invasive surgical techniques involving placement of a mechanical barrier in the inferior vena cava have been developed. These barriers are in the form of filters and are typically inserted through either the femoral vein in the patient's leg or the right jugular vein in the patient's neck or arm under local anesthesia. The filters are then advanced intravascularly to the inferior vena cava where they are expanded to block migration of the blood clots from the lower portion of the body to the heart and lungs.
These prior filters take various forms. One type of filter is composed of coiled wires such as disclosed in U.S. Pat. Nos. 5,893,869 and 6,059,825. Another type of filter consists of legs with free ends having anchors for embedding in the vessel wall to hold the filter. These filters are disclosed, for example, in U.S. Pat. Nos. 4,688,553, 4,781,173, 4,832,055, and 5,059,205, 5,984,947 and 6,007,558. Another type of filter is disclosed in U.S. Pat. No. 6,214,025 consisting of wires twisted together to form a cylindrical anchoring portion conforming to the inner vessel wall surface to exert a radial force and a conical filtering portion.
Commonly assigned U.S. Pat. No. 7,704,266 (the “266 patent”) and U.S. Pat. No. 8,162,972 (the “972 patent”), the entire contents of both of which are incorporated herein by reference, disclose other forms of vein filters. These filters can be permanently implanted or removed minimally invasively, e.g. intravascularly.
The methods of placement of the filter described in the '274 and '972 patents are effective. However, in certain patients, the vena cava is not straight, but is curved and/or more tortuous. Although the filters of the '274 patent and '972 patents can be placed effectively in such vena cava, it would be advantageous to provide a delivery method and apparatus to even better accommodate these curved anatomies.
Additionally, the better centered the filter, the easier the subsequent removal of the filter. This is due to the fact that if the retrieval end (cranial end) of the filter is against the vessel wall when placed, access to the retrieval end could be difficult. Also, additional tissue ingrowth could occur over the cranial end which could increase the difficulty of removal.
Prior art attempts to center the filter include modifications to the filter itself to provide centering structure. Not only does this complicate the filter design but could require the length of the filter to be increased. Such increased length can be disadvantageous due to limited space in the inferior vena cava.
Commonly assigned Patent Publication No. 2009/0143813 (Ser. No. 12/288,217, filed Oct. 17, 2008) discloses an attempt to center the filter without modifying the filter. In this patent publication, the delivery system is modified to provide for more centered placement of the filter by moving the delivery sheath opening toward a center of the vessel by use of a curved pusher. Although in certain applications this method has been effective, sometimes the user does not properly perform the technique and therefore the filter is not centered upon delivery.
Therefore, it would be advantageous to improve centered delivery of a filter within the vessel by modifications of the filter delivery system, rather than the filter itself, and which can provide a more reliable and consistent technique for centered placement.
The present invention provides a method of implanting a vein filter to facilitate centering of the filter at the surgical site. The present invention also provides a method of delivering the filter in a manner to facilitate later removal of the filter from the vessel. This is achieved by providing an expandable centering member as part of the delivery system which is preferably movable with respect to the pusher utilized for deploying the filter in the vessel.
In one aspect, the present invention provides a method of implanting a vessel filter in a vessel by a femoral approach comprising the steps of:
In some embodiments, the method includes the step of advancing the sheath through the femoral vein into the vena cava.
In some embodiments, the pusher includes a lumen extending therein, and the centering structure includes a wire, the wire movable within the lumen of the pusher and through the filter. The pusher can have a stepped portion forming a shoulder to support the filter and the vessel filter can be mounted on the pusher within the sheath.
In some embodiments, the centering structure includes a plurality of wires extending from an apex and terminating in free ends; in other embodiments, the centering structure includes a plurality of wires extending from an apex and joined at terminal ends. In some embodiments, the centering structure includes a plurality of wires bowing radially outwardly in the expanded configuration.
In some embodiments, the step of subsequently exposing the filter includes the step of moving the pusher and/or sheath relative to each other.
The method can further include the step of removing the vein filter from the vessel.
In accordance with another aspect, an implantation system for a vascular implant is provided comprising a sheath having a longitudinal axis, a lumen formed therein and a distal opening. A pusher is positioned within the sheath in contact with the vascular implant to deliver the implant from the sheath, the implant moving from a reduced profile position within the sheath to an expanded placement position when exposed from the sheath. The implant is configured for deployment through the distal opening in the sheath for implantation in a patient's body. A centering structure includes an elongated portion and a plurality of arms extending from a distal portion of the elongated portion, the arms movable from a reduced profile position to an expanded position to move the sheath away from the vessel wall to a more centered position, and the centering structure is movable relative to the pusher.
In some embodiments, the pusher comprises a lumen and the centering structure is slidably positioned within the pusher. In some embodiments, the pusher includes a stepped portion forming a shoulder to support the implant.
Preferably, the centering structure is movable independent of the pusher and is movable through the implant.
In some embodiments, the arms of the centering structure are joined at an apex and terminate in free ends; in other embodiments, the arms are joined at proximal and distal ends to form a basket like structure.
In some embodiments, the implant comprises a vessel filter, the filter moving to the expanded position when deployed from the sheath.
In accordance with another aspect, the present invention provides in combination, a delivery sheath, a filter, a pusher and a centering structure. The delivery sheath has a lumen therein dimensioned to receive the filter, the filter positioned within the sheath and configured for deployment through a distal opening in the sheath for implantation in a patient's body. The pusher is slidably positioned with respect to the sheath and engages the filter for deployment of the filter from the sheath. The centering structure is slidably positioned with respect to the filter, pusher and sheath, and has an expandable distal portion to aid centering of the sheath and thus centering of the filter upon delivery of the filter from the delivery sheath.
In some embodiments, the centering structure is slidable within a lumen of the pusher.
Preferred embodiment(s) of the present disclosure are described herein with reference to the drawings wherein:
Turning now to the drawings, wherein like reference numerals identify similar or like components throughout the several views, a method of implanting vein filters is disclosed. The filter is inserted via a femoral approach. In commonly assigned U.S. Pat. Nos. 7,704,266 and 8,162,972, the entire contents of each of which are incorporated herein by reference, various embodiments of filters are described with various structures. The delivery system of the present invention can be used to insert the filters disclosed in these patents as well as used to insert other filters.
As is common, the term “proximal” used herein refers to the part closer to the user, e.g., surgeon, and the term “distal” refers to the part further from the user. Thus, for example, the distal opening of the delivery sheath is the part further from the user as the proximal end extends from the patient's body for manipulation by the user.
Turning initially to
Delivery sheath (catheter) 20 has a distal tip 24 and a distal opening 26 at distal portion 22 (
The filter pusher 30 has a distal tip 32 and a lumen 34 extending therethrough (see
The pusher 30 can be formed from a tube. In a preferred embodiment, the pusher 30 can be formed of Pebax material. The centering wires can be composed of stainless steel. Other materials and compositions of the pusher and wires are contemplated. A wire protruding beyond the distal end of the pusher 30 also can serve as a guidewire. The wire can also help keep the vessel engaging hooks of the filter separated during insertion. A marker band or other indicia can be provided to provide a visual indication of when the filter is at the distal end of the sheath (when the markings are adjacent a proximal end of a filter cartridge). Note in some embodiments, the centering wire can be attached to a hub of the pusher for slidable movement, e.g., by a control knob, such as in the embodiment described below.
The centering structure is designated by generally by reference numeral 40 and has a distal portion 42 and a proximal portion extending outside the body for manipulation by the user. Distal portion 42 includes a plurality of centering arms 44, joined at apex 46, bowing radially outwardly and terminating in free ends 48 (
In one embodiment, the centering structure 40 is formed by a series of wires, e.g., an elongated wire 43 with centering arms 44 formed of separate wires and attached to a distal portion of the wire 43 at apex 46 such as by welding, crimping, soldering, bonding or other known methods. Alternatively, the elongated wire 43 can form one of the centering arms and then additional centering arms 44 can be attached to a region of the elongated wire 43 slightly proximal of its distal tip (as in the location of apex 46). The centering structure can alternatively be formed integrally from a monolithic wire or hypotube. The one piece structure can be laser cut and shape set.
The wires of the centering structure can be made of shape memory material such as Nitinol. In this manner, the wires are collapsed into a low profile position where the arms 44 are substantially aligned with a longitudinal axis of the delivery sheath 20 for delivery. When advanced from the sheath 20, the centering wires are exposed and return to their shape memorized expanded configuration (position) of
Note in the expanded position, the apex 46 can be exposed; alternatively the apex 46 can remain within the confines of the sheath 20 or pusher 30.
As shown, when the centering wires expand, they have a transverse dimension sufficiently large to contact, preferentially circumferentially, the wall of the vessel, thereby keeping the delivery sheath 20 and distal tip 32 of the pusher 30 substantially centered within the vessel. It should be appreciated that the term “substantially centered” as used herein includes exactly centered within the vessel as well as slightly off center such as at an angle of up to about 30 degrees with respect to the longitudinal axis of the vessel, but preferably smaller. By keeping this angle closer to zero, centering of the delivery sheath distal tip 24 and distal opening 26, and therefore the filter 100 when delivered, can better be achieved.
An alternate embodiment of the centering structure is illustrated in
Centering structure 140 differs from centering structure 40 in that it is a closed loop design. More specifically, distal portion 142 includes a plurality of centering arms 144, joined at proximal apex 146 and at distal converging region 147. The connection at distal region 147 provides more structural integrity. Centering arms 144 bow radially outwardly between their proximal and distal fixed points. In a preferred embodiment, three centering arms 144 are provided, however, a fewer or greater number of arms can alternatively be provided. The centering structure 140 is slidably positioned within a lumen of the filter pusher 130 (similar to lumen 34 of pusher 30) and therefore moves, e.g., slides, relative to the pusher 130, sheath 120 and filter 100. That is, the centering structure 140 is movable from a retracted position within the delivery sheath 120 to an extended (advanced) or exposed position where it extends beyond the distal tip of sheath 120 for movement from a collapsed position to the expanded position of
In one embodiment, the centering structure is formed by a series of wires, e.g., an elongated wire 143 (
The wires of the centering structure can be made of shape memory material. In this manner, the wires are collapsed into a low profile position where the arms 144 are substantially aligned with a longitudinal axis of the delivery sheath 120 for delivery. When advanced from the sheath 120, the wires are exposed and return to their shape memorized expanded configuration (position) of
As shown, when the wires expand, the have a transverse dimension sufficiently large to contact the wall of the vessel, thereby keeping the delivery sheath 120 and distal tip 122 of pusher 120 substantially centered within the vessel. Substantially centered as noted above includes exactly centered as well as slightly off center such as at an angle of up to 30 degrees with respect to the longitudinal axis, but preferably smaller. By keeping this angle closer to zero, centering of the opening of the delivery sheath 120, and therefore the filter 100 when delivered, can better be achieved.
Turning to the embodiment of
In the embodiment of
The centering structures described herein are self-expanding, e.g., composed of a shape memory material that automatically returns to the expanded position of
The use of the filter implantation system will now be described. It should be understood that the method of use will be described in conjunction with the centering structure 40 of
In use, once the sheath 20 and dilator (not shown) are inserted through the femoral vein and advanced through the iliac vein into the inferior vena cava, the dilator is removed. Due to the anatomy of the particular patient's vena cava C, the sheath 20 may end up off center such as against the vessel wall V such that distal opening is close to the vessel wall (see
Note that during intravascular insertion of the sheath 20 into the vena cava C, filter pusher 30, filter 100 and centering structure 40 positioned therein are fully covered by sheath 20 so as not to be exposed (
Next, the centering structure 40 is advanced distally from the sheath 20 (
The filter 100 is exposed from the sheath 20 (
Once the filter 100 is fully deployed in the vessel, the centering structure 40 is then retracted proximally by the user, and the centering arms 44 are thereby collapsed within the lumen 34 of the pusher 30 as it is withdrawn through the pusher 30 and into the sheath 20 (
Note the Figures illustrate filter 100 identical to the filter of U.S. Pat. No. 8,162,972 incorporated by reference above as one example of a filter that can be utilized with the delivery system of the present invention Thus, filter 100 is preferably formed from a single tube, and is preferably composed of shape memory material such as Nitinol. A plurality of cutouts are formed in the filter 100, preferably by laser cutting, although other techniques are contemplated to thereby form struts 114.
Filter 100, as shown in the expanded configuration of
The struts 114 of filter 1010 terminate in hooks 172. In some embodiments, some struts can terminate in a hook larger than the hook of other struts. In some embodiments, the struts 114 can terminate in alternating larger and smaller hooks such that every other strut 114 would terminate in a small hook and the other struts (in between) would terminate in a larger hook. The penetrating tips 176 of hooks 172 penetrate the tissue to retain the filter, preferably temporarily, and point toward the cranial end of the filter.
The six filter struts or strut portions 114 extend longitudinally and then curve outwardly from tubular portion 118, extend radially therefrom and divide into two connecting filter struts or strut portions 114a, 114b (preferably of equal width, although differing dimensions are contemplated) that angle way from each other (in different directions) to extend to the connecting strut portion of an adjacent strut 114. Thus, connecting strut portion 114a of one strut 114 interconnects with the connecting strut portion 114b of an adjacent strut at joining region 114d. This forms closed geometric shapes 125, preferably substantially diamond shaped in configuration. For clarity, not all of the identical parts are labeled in the drawings.
In the illustrated embodiment, preferably six struts are provided forming twelve interconnecting struts; however a different number of struts and closed geometric shapes can be provided. Note that although all six struts 114 are shown interconnected, it is also contemplated that fewer than all the struts can be interconnected. Also, the strut width can vary as described with respect to the filters disclosed in the '972 patent.
After convergence of strut portions 114a, 114b at joining region 114d, it transitions into elongated mounting strut portions 114c which form the flared mounting or anchoring region 130. The length of the strut portions 114c in the anchoring region 130 can vary, with increased/decreased length increasing the flexibility/rigidity of the struts. The thickness of the strut portions can also vary to affect flexibility/rigidity.
The tubular portion 118 is preferably in the form of a retrieval hook 192. In an alternate embodiment, instead of a retrieval hook 102, a ball or groove can be provided engageable by the retrieval snare (not shown) for retrieval of the filter.
Note that the tubular region 118 has a lumen 119 therethrough (see
After exposure of the filter 100 by advancing the pusher 30 to eject the filter 100 or retracting the sheath 20 with the pusher 30 held stationary, or relative movement of both the pusher 30 and sheath 20, the pusher 30 and sheath 20 are removed, enabling the filter 100 to expand from its collapsed position of
If it is later desired to remove the filter, the retrieval methods for the filter which are illustrated and described in detail in the '972 patent, such as a retrieval snare, can be utilized.
If the filter 100 is more centered in the vessel, the retrieval snare is better adapted to access and engage (grasp) the retrieval region, e.g., the retrieval hook 192, of the filter 100. Also, if placement is more centered, removal can be easier because there will be less tissue ingrowth at the retrieval region.
Although described for inserting a vessel filter, the pusher and sheath can be utilized to insert other implants, including vascular implants such as a stent or valve.
While the above description contains many specifics, those specifics should not be construed as limitations on the scope of the disclosure, but merely as exemplifications of preferred embodiments thereof. Those skilled in the art will envision many other possible variations that are within the scope and spirit of the disclosure as defined by the claims appended hereto.
This application claims priority from provisional application Ser. No. 61/988,051, filed on May 2, 2014, the entire contents of which are incorporated herein by reference.
| Number | Date | Country | |
|---|---|---|---|
| 61988051 | May 2014 | US |
