CN114845665A

CN114845665A - Absorbable blood vessel filter

Info

Publication number: CN114845665A
Application number: CN202080089048.8A
Authority: CN
Inventors: 米切尔·唐恩·埃格斯
Original assignee: CROSSROAD LABS
Current assignee: CROSSROAD LABS
Priority date: 2019-10-21
Filing date: 2020-10-19
Publication date: 2022-08-02
Also published as: CA3155354A1; EP4048197A4; KR20220119007A; JP2022553341A; EP4048197A1; WO2021080923A1; AU2020369971A1

Abstract

An absorbable vascular filter for deployment within a blood vessel for temporary filtration of bodily fluids is disclosed. One embodiment is configured for placement of such absorbable vascular filters within the Inferior Vena Cava (IVC) to filter emboli to prevent Pulmonary Embolism (PE) for a limited period of time in time. Once protection of the PE is complete, the filter will biodegrade according to a scheduled schedule determined by the absorption characteristics of the filter components. Thus, the temporary absorbable vascular filter avoids long-term complications of permanent IVC filters, such as increased deep vein thrombosis, adjacent organ puncture and embolization due to filter rupture, while also circumventing the requirement for metal retrievable IVC filter removal.

Description

Absorbable blood vessel filter

Cross Reference to Related Applications

This application claims priority from the following patents: CIP patent application No.16/659,536, filed on 21/10/2019, is a continuation-in-part application of U.S. patent application serial No.13/403,790 by Mitchell Eggers, entitled "insoluble vacuum Filter", filed electronically on 23/2/2012, which continuation-in-part application is a continuation-in-part application of U.S. patent application serial No.13/096,049 by Mitchell Eggers, filed electronically on 28/4/2011, entitled "vacuum Filter tent", which continuation-in-part application is a continuation-in-part application of U.S. patent application serial No.13/036,351 by Mitchell Eggers, filed electronically on 28/2011, 2/28, entitled "insoluble vacuum Filter", all of which are expressly incorporated herein by reference in their entirety.

Technical Field

The present invention relates generally to vascular filters, and more particularly to absorbable vascular filters that are deployed within a blood vessel to temporarily filter bodily fluids. Embodiments are configured to place such absorbable vascular filters within the Inferior Vena Cava (IVC) to prevent pulmonary artery embolization for a specific period of time, which is determined by the absorption properties of the filter.

Background

Between 10 and 30 million americans die of Pulmonary Embolism (PE) each year, which is the third leading cause of death in the united states, exceeding the total number of deaths from breast cancer and aids [1-5 ]. Similar incidence of PE is found in europe, resulting in approximately 370,000 deaths per year [6 ]. Furthermore, PE is the third most common cause of death in the first 24-hour surviving trauma patient. It is estimated that 25% of all hospitalized patients have some form of Deep Vein Thrombosis (DVT) which is often not clinically evident if PE is not formed [7 ]. On average, 33% of DVT will progress to symptomatic PE, of which 10% will be fatal [6 ].

The American Surgeon Council (The US Surgeon General) has recognized this alarming statistic and has formally called out to take action against DVT and PE in 2008 [1 ]. Unfortunately, DVT/PE severely affects the elderly, in part because of long-term inactivity following medical treatment. Under the age of 50, the incidence is relatively low (1/100,000), and at the age of 85, the incidence accelerates exponentially to 1000/100,000[8 ]. Thus, the american surgeon's council has announced that: the number of DVT/PE cases in the aging population of the United states increases beyond population growth if better precautions are not taken [1 ].

The risk factors for PE due to DVT are similar to the Welch three-character (Virchow' striated) [9 ]: (i) endothelial damage, (ii) hypercoagulability, (iii) hemodynamic changes (stasis or turbulence). Thus, specific risk factors include: hip and knee replacement, abdominal, pelvic and extremity surgery, pelvic and long bone fractures, prolonged immobility (e.g. prolonged hospitalization and air travel), paralysis, advanced age, advanced DVT, cancer, obesity, COPD (chronic obstructive pulmonary disease), diabetes and CHF (chronic heart failure). Orthopedists are of particular interest because their patients have a risk probability of encountering DVT and PE of 40% -80% after knee and hip surgery without preventive treatment [10-12 ].

The american academy of sciences orthopedics doctor association (AAOS) has published guidelines for prevention of PE. Basically, for patients at standard risk, chemopreventive agents such as aspirin, Low Molecular Weight Heparin (LMWH), synthetic pentasaccharides (pentasaccharides), or warfarin (warfarin) should be considered, in addition to intra-operative mechanical prophylaxis and/or post-operative immediate mechanical prophylaxis [13 ].

Aspirin reduces the relative risk in symptomatic DVT by 29% and the relative risk of fatal PE by 58% [14 ]. LMWH reduces the risk in DVT by 30% and has been shown to be more effective than plain heparin in high risk populations (such as hip and knee arthroplasty populations) [7 ]. To achieve International Normalized Ratio (INR) results between 2 and 3, warfarin was started as a secondary prevention thrombus for 3 months within 24 to 48 hours of heparin introduction, which would reduce the risk of recurrent Venous Thromboembolism (VTE) by 90% compared to placebo. Mechanical precautions (including pneumatic compression devices that repeatedly compress the legs with a balloon) are also used with anticoagulants to reduce the occurrence of PE.

The duration of prevention depends on the underlying cause of DVT formation. Prevention is currently recommended for moderate to high risk surgery for a minimum of 7-10 days, and for many orthopedic surgeries up to 28-35 days. In particular, in trauma orthopedics, DVT prevention continues until patient activity (32%), hospitalized patient discharge (19%), 3 weeks post-surgery (16%), 6 weeks post-surgery (27%), and in rare cases, for more than 6 weeks (7%) [17 ]. Studies have shown that hypercoagulability (hypercoagulability) remains for at least one month after injury in 80% of trauma patients [18 ]. For total knee and hip replacement and cancer surgery, 35 days of prophylactic treatment is recommended [12,19 ]. Overall, prophylactic treatment of a possible VTE is often warranted up to 6 weeks after trauma or major surgery.

Contraindications for pharmacological prophylaxis include active bleeding, bleeding diathesis, hemorrhagic stroke, neurosurgery, trauma, hemothorax, fractures of the pelvis or lower limb with intracranial hemorrhage, anticoagulation interruptions, and recent DVT/PE patients undergoing surgery.

For patients with contraindications for the above anticoagulant prophylaxis, or patients with failed anticoagulant therapy, AAOS, american college of physicians, and the british standard committee on hematology recommend the use of Inferior Vena Cava (IVC) filters [13,20,21 ]. These intravascular metal filters are deployed through a catheter into the IVC to substantially capture emboli generated by the DVT before it reaches the lungs resulting in PE. Furthermore, the british standard committee on hematology recommends the placement of IVC filters in pregnant patients who have anticoagulation contraindications and develop extensive VTE shortly before delivery (within 2 weeks).

The Eastern society of Trauma Surgery (The Eastern Association for Surgery of Trauma) also recommends The placement of prophylactic IVC filters in patients with increased risk of bleeding and prolonged bedridden Trauma [22 ]. This preventive recommendation follows the results of a study showing a low rate of PE in severely polytraumatised patients who have undergone IVC placement [23-25 ]. Indeed, the entire IVC filter user has grown from 49,000 units in 1999 to 167,000 units in 2007, and projected to reach 259,000 units in 2012, this rapidly growing data is the market for using recoverable IVC filter prophylaxis [26, 27 ].

Exemplary vascular filters primarily for IVC placement are disclosed in the following patent documents: U.S. Pat. No.4,425,908; U.S. Pat. No.4,655,771, U.S. Pat. No.4,817,600; U.S. Pat. No.5,626,605; U.S. Pat. No.6,146,404; pat. No.6,217,600B 1; U.S. Pat. No.6,258,026B 1; U.S. Pat. No.6,497,709B 1; U.S. Pat. No.6,506,205B 2; U.S. Pat. No.6,517,559B 1; pat. No.6,620,183b 2; U.S. Pat. app. pub.no. 2003/0176888; U.S. Pat. App. Pub. No. 2004/0193209; U.S. Pat. App. Pub.No. 2005/0267512; U.S. Pat. App. Pub.No. 2005/0267515; U.S. Pat. App. Pub.No. 2006/0206138A 1; U.S. Pat. app. pub.no.2007/0112372 a 1; u.s.pat.app.pub.no.2008/0027481 a 1; u.s.pat.app.pub.no.2009/0192543 a 1; u.s.pat.app.pub.no.2009/0299403 a 1; u.s.pat.app.pub.no.2010/0016881 a 1; u.s.pat.app.pub.no.2010/0042135 a 1; and u.s.pat.app.pub.no.2010/0174310 a 1.

IVC filter efficacy has been demonstrated in several studies of class I and class II evidence [22, 28-30 ]. Most filters installed earlier are expected to become permanent fixation devices, with endothelialization occurring within 7-10 days, making most models impractical to remove without irreversible vascular damage, IVC dissection, and thrombosis leading to life-threatening bleeding. While these permanent filters have prevented PE, they have been shown to actually increase the risk of recurrent DVT formation over time.

In particular, a Cochrane review [31] on the use of IVC filters to prevent PE cites a class I random prospective clinical trial [32] published by decaus et al, in which the incidence of DVT with an IVC filter cohort (cohort) increased by nearly 2-fold: (i) in

year

2, 21% of recurrent DVT morbidity in the filter cohort versus 12% (P ═ 0.02) in the filterless LMWH cohort, and (ii) in year 8, 36% of recurrent DVT morbidity in the filter cohort versus 15% (P ═ 0.042) in the filterless cohort [33 ]. However, the filter does reduce the occurrence of PE; a filter queue that suffers from only 1% of PEs versus a no filter queue (P ═ 0.03) that has 5% of PEs disclosed on the first 12 days. No statistically significant difference in mortality was seen at any time range investigated. Clearly, the initial benefit of reduced PE caused by the permanent IVC filter is offset by the increase in DVT without any difference in mortality.

In addition to the increased incidence of DVT due to prolonged IVC filter deployment, the incidence of filter obstruction was reported to be 6% to 30%, as well as the incidence of filter migration (3% to 69%), venous insufficiency (5% to 59), and post-thrombotic syndrome (13% to 41%) [34-36 ]. Insertion complications including hematoma, infection, pneumothorax, vocal cord paralysis, stroke, air embolism, dislocation, obliterative arteriovenous fistula, and inadvertent carotid puncture have a 4% -11% incidence [37 ].

Temporary or recyclable IVC filters have recently been sold with the intention of removing them once the risk of PE subsides, thereby circumventing many of the harmful complications of permanent filters. The recyclable filter provides features of flexible hooks, collapsed components, and unconstrained brackets, allowing easy recycling. Unfortunately, these same features lead to unwanted filter shifting, fatigue failure, IVC penetration, debris migration to the hepatic vein and pulmonary artery, filter tilting and metal emboli [38-43 ]. Since 2005, 921 adverse filter events were reported to the FDA including 328 device migrations, 146 device detachments (metal plugs), 70 IVC punctures, and 56 filter disintegrations [44 ]. Some recoverable brands have a striking failure rate, such as 25% fragmentation accidents of the Bard Recovery filter over a 50 month period, which result in end organ embolism. 71% of the debris that causes the cardiac embolism causes life-threatening ventricular tachycardia, pericardial tamponade, and in some cases sudden death. Another recoverable model (Bard G2) resulted in a 12% fragmentation rate over a 24 month period [45 ]. The incidence of fragmentation of such devices is assumed to be proportional to the dwell time.

These failure incidents and other problems have prompted the FDA to issue a formal announcement at 8 months 2010 that indicates: "FDA recommendations, implanters and clinicians responsible for recyclable IVC filters with constant attention to patients should consider removing the filter as soon as protection against PE is no longer needed" [44 ]. Although these types of retrievable filters are intended to be removed over a period of months, some studies have shown that about 70% -81% of patients with retrievable IVC filters do not return to the hospital to remove the filters, leaving thousands of patients in life-threatening adverse events caused by long-term retrievable IVC filter placement [41,44,46-48 ]. These patients either lost follow-up or refused to remove the filter without complications.

Disclosure of Invention

The present invention includes systems and methods for filtering fluids. Certain embodiments include novel absorbable vascular filters that temporarily prevent pulmonary embolism by capturing or inhibiting emboli within a body vessel. Absorbable vascular filters, according to certain aspects of the present invention, have various advantages over all conventional vascular filters, including long-term, temporary, and optional IVC filters. Most importantly, the absorbable vascular filters disclosed herein biodegrade slowly within the blood vessel according to a planned protocol designed according to the selection of absorbable filter materials that do not require removal of the filter. Furthermore, absorbable vascular filter elements are made from non-metallic synthetic polymers that degrade by careful design without adverse effects on the end organ as shown by conventional metallic IVC filters, which migrate and tend to divide into several parts. In addition, the abnormal increase in DVT seen with conventional long-term IVC filters may be circumvented due to the relatively short dwell time (months) of the absorbable vascular filter.

Drawings

Figure 1a is a cut-away isometric view of one embodiment of an absorbable vascular filter, including staged sequential biodegradation of the absorbable capture elements.

FIG. 1b depicts the capture element of FIG. 1a in detail.

Fig. 1c depicts features of the capture element of fig. 1b at a later point in time, wherein a proximal portion of the capture element is bioabsorbed/biodegraded.

Fig. 1d depicts the characteristics of the capture element of fig. 1c at a later point in time, wherein the proximal and intermediate portions of the capture element have been bioabsorbable/biodegradable, leaving only the distal portion.

Fig. 1e depicts the complete bioabsorption/biodegradation of the capture element of fig. 1b at the most distant point in time.

Fig. 2a is a schematic cross-sectional view of another embodiment of an absorbable vascular filter, further depicting staged sequential biodegradation of the absorbable capture elements.

Fig. 2b is an enlarged end view of the absorbable capture element of the absorbable filter depicted in fig. 2 a.

Fig. 2c depicts the capture element of fig. 2b when the filter is installed in a blood vessel.

Fig. 2d depicts the capture element of fig. 2c at a later point in time, wherein the inner capture ring element has been bioabsorbable/biodegradable.

Fig. 2e depicts the capture element of fig. 2d at a later point in time, wherein one of the annularly mounted capture elements has been bioabsorbable/biodegradable.

Fig. 2f depicts the capture element of fig. 2e at a later point in time, wherein two circumferentially mounted capture elements have been bioabsorbable/biodegradable.

Fig. 2g depicts the capture element of fig. 2f at a later point in time, wherein only one loop-mounted capture element remains after bioabsorption/biodegradation.

Figure 2h depicts the capture element of figure 2b at the furthest time point, which has been completely bioabsorbed/biodegraded.

Figure 3a is a cut-away isometric view of one embodiment of a vascular filter including a plurality of capture elements coupled to the stent to filter material, such as emboli.

Figure 3b depicts the capture element in figure 3a in detail.

Figure 4a is an absorbable vascular filter constructed from poly-p-dioxanone sutures having thickness (size) of 3-0, 2-0, 0 and 1 in a mesh pattern, the absorbable vascular filter characterized by: the degradation is continued according to the different diameters and the expiration date of the capture elements.

Fig. 4b is an absorbable vascular filter constructed from poly-p-dioxanone sutures in a design similar to the mesh design in fig. 4a, except that only thickness 2-0 is used.

Figure 4c is an absorbable vascular filter constructed from poly-p-dioxanone sutures of thickness 2-0 in the radial pattern of a conventional typical IVC filter.

FIG. 4d is an absorbable vascular filter constructed from poly-p-dioxanone sutures of thickness 3-0, 2-0, 0 and 1 in a radial pattern, the absorbable vascular filter characterized by: the degradation is continued according to the different diameters of the capture elements.

Figure 5 shows photographs of the absorbable filters appearing in figure 4a at

weeks

0, 7, 13-22 during in vitro testing, showing continued degradation of the filter by untwisting 1 to 2 capture elements per week starting at week 13 and reaching final disintegration at week 22.

Fig. 6 is a graph of the average breaking load (kg/strand) of the polydioxanone capture elements as a function of time during in vitro testing.

Figure 7 is a graph of strength retention of a polydioxanone capture element as a function of time expressed as a percentage of initial strength.

Figure 8 is a graph of young's modulus of a polydioxanone capture element as a function of time during in vitro testing.

FIG. 9a is a cross-sectional schematic view showing a preferred method of installing an absorbable vascular filter using a catheter-based system, wherein the absorbable vascular filter is in a compression mode.

Figure 9b is a cross-sectional schematic diagram detailing deployment of an absorbable vascular filter using a catheter-based system with a sliding outer sheath to deploy the absorbable vascular filter in a fully expanded manner.

Fig. 9c is a cross-sectional schematic detailing the removal of a central stabilizer bar or piston for stabilizing an absorbable vascular filter while the outer sheath of the catheter-based mounting system is removed.

Fig. 9d illustrates the operation of the absorbable vascular filter in the presence of emboli in the blood vessel.

Figure 9e shows the blood vessel after complete biodegradation/bioabsorption of the absorbable vascular filter.

Figure 10a illustrates one embodiment of an absorbable vascular filter constructed from a braided or woven stent integrated with a capture basket.

Fig. 10b is a related top view of the absorbable vascular filter shown in fig. 10 a.

Fig. 11 is an enlarged view of the weave or braid of the absorbable elements comprising the stent portion of the absorbable vascular filter.

Fig. 12 is an enlarged view of the weave or braid of absorbable elements including both the stent portion of the integrated absorbable vascular filter and the capture basket.

Fig. 13a is a photograph of an integrated absorbable IVC filter woven with a single synthetic filament.

Fig. 13b is an end view photograph of the integrated absorbable IVC filter shown in fig. 13 a.

Fig. 14a is an isometric view of one embodiment of an absorbable vascular filter cut from a generally tubular material whereby the filter apices are formed by securing capture elements with a wire.

Fig. 14b is a corresponding isometric view of an embodiment of an absorbable vascular filter cut from a generally tubular material whereby the filter apices are formed by securing capture elements with a wire.

Figure 15a is an isometric view of one embodiment of an absorbable vascular filter cut from a generally tubular material whereby the filter apices are formed by securing capture elements with a splined endplate.

Fig. 15b is a corresponding isometric view of an embodiment of an absorbable vascular filter cut from a generally tubular material whereby the filter apices are formed by securing capture elements with a splined end plate.

Figure 16a is an isometric view of one embodiment of an absorbable vascular filter cut from a generally tubular material whereby the filter apex is formed by securing a capture element with an endplate having a mating connection axis.

Fig. 16b is a corresponding isometric view of an embodiment of an absorbable vascular filter cut from a generally tubular material whereby the filter apex is formed by securing a capture element with an end plate having a mating connection shaft.

Fig. 17a is an isometric view of an embodiment of an absorbable vascular filter cut from a generally tubular material whereby the filter apices are formed by securing capture elements with endplates.

Fig. 17b is a corresponding isometric view of an embodiment of an absorbable vascular filter cut from a generally tubular material whereby the filter apices are formed by securing capture elements with endplates.

Figure 18a is an isometric view of one embodiment of an absorbable vascular filter wherein the ring-shaped elements are cut from a generally tubular material and the filter basket is formed of absorbable wire capture elements that are connected together and secured at the apex with an end plate.

Fig. 18b is a corresponding isometric view of an embodiment of an absorbable vascular filter in which the ring-shaped elements are cut from a generally tubular material and the filter basket is formed of absorbable wire capture elements connected together and secured at the apex with an end plate.

Detailed Description

Embodiments of the present invention will now be described in detail with reference to the drawings and figures, which are provided as illustrative examples to enable those skilled in the art to practice the invention. It is noted that the figures and examples below are not meant to limit the scope of the present invention to a single embodiment, but that other embodiments are possible by way of interchange of some or all of the described or illustrated elements. Wherever convenient, the same reference numbers will be used throughout the drawings to refer to the same or like parts. If certain elements of these embodiments can be partially or fully implemented using known components, only those portions of the known components that are necessary for an understanding of the present invention will be described, and detailed descriptions of other portions of the known components will be omitted so as not to obscure the invention. In this specification, embodiments illustrating individual components should not be considered limiting; rather, the invention is intended to cover other embodiments including a plurality of the same components, and vice versa, unless the context clearly dictates otherwise. Moreover, applicants do not intend for any term in the specification or claims to be ascribed an uncommon or special meaning unless explicitly set forth as such. Additionally, the present invention includes present and future known equivalents to the components referred to herein by way of illustration.

Referring to the embodiment shown in fig. 1a-e, absorbable vascular filter 1 includes an outer annular element 2 for supporting a plurality of absorbable filter capture elements (30-32, 40-41). The capture element is specifically designed to be bioabsorbed and/or biodegraded in a continuous manner to avoid the entire filter from detaching at the same time, causing undesirable emboli. Continued degradation may be controlled by selecting absorbable polymers having different absorption profiles (profiles), diameters, and/or effective dates. In addition, an absorbent attachment may be incorporated which serves as a detachment point during absorption. Sequential bioabsorption/biodegradation is shown in fig. 1b-e, wherein the disintegration begins at the proximal capture element 30, progresses to the capture element 31 in the middle portion, and finally is completely bioabsorption/biodegradation as depicted in fig. 1 e.

The continuous bioabsorption/biodegradation of the capture element thus designed can be achieved using a large number of synthetic materials. The goal is to select an absorbable filter material to match the desired filter residence time. According to the background section of the prior art, a filter dwell time of 6 weeks would be appropriate for IVC filters to prevent post-traumatic PE or PE associated with major surgery. Synthetic materials that can be used to form the capture element include:

poly-p-dioxanone (PDO, PDS) -colorless crystalline, biodegradable synthetic polymers having multiple repeating ether-ester units. For the suture form, PDSII (Ethicon, Somerville, new jersey) with a thickness of 4/0 or less retained 60%, 40%, and 35% of its tensile strength at

weeks

2, 4, and 6, respectively. PDS II with a thickness of 3/0 and greater retained 80%, 70%, and 60% of its tensile strength at week 2, week 4, and week 6, respectively. In addition to providing 6 weeks of winding support, PDS II sutures were fully absorbed by hydrolysis within 183-. Basically, absorption is minimal within the first 90 days and is essentially complete within 6 months. Finally, PDS has low affinity for microorganisms with minimal tissue reaction.

Polytrimethylene carbonate (Maxon) -resembles PDS in absorption curve but the breaking strength is slightly higher. Maxon (Covidien, Mansfield, MA) maintained 81%, 59% and 30% of its tensile strength at

weeks

2, 4 and 6, respectively, and it hydrolyzed completely within 210 days 180-.

Polylactide glycolide copolymer 910(Polyglactin 910) (Vicryl) -a copolymer of lactide and glycolide (Polyglactin 370). For the suture form, vicryl (Ethicon) with a thickness of 6/0 or greater retained 75%, 50%, and 25% of its tensile strength at

weeks

2, 3, and 4, respectively, and was completely absorbed within 56-70 days.

Polyglycolic acid (dixon) -similar to lactide-glycolide copolymers, is made from polyglycolic acid and coated with polyethylene lactone (polycaprolate). Dixolone also has a tensile strength and absorption curve similar to that of lactide-glycolide copolymers.

Synthetic copolymers of polycarbophil 25(Monocryl) -glycolide and e-caprolactone. Monocryl (Ethicon) maintained 50% -70% and 20% -40% of its tensile strength at week 1 and week 2, respectively, and was completely absorbed over days 91-119.

Polylactic acid-glycolic acid copolymer (PLGA) -a copolymer of monomeric glycolic acid and lactic acid. By controlling the ratio of lactide and glycolide used for polymerization, PLGA can be produced in different forms and properties. Like other synthetic absorbable materials, PLGA degrades by hydrolysis, with the absorption curve depending on the monomer ratio; the higher the glycolide content, the faster the degradation. However, the 50:50 copolymer showed the fastest degradation at month 2. PLGA has minimal systemic toxicity as the polymer degrades in vivo to produce lactic acid and glycolic acid, both of which are normal physiological substances.

poly-L-lactic acid (PLA) is also a polymer made of lactic acid, but has a rather long lifetime. In the vicinity of the soft tissue, PLA remained intact for 28 weeks and was completely absorbed within 52 weeks.

As an example of designing the capture elements to degrade continuously after a PE prevention period, the

proximal capture elements

30,41 may be made with PDS II suture of thickness 4/0 (0.15 mm diameter), while the

middle capture elements

31,40 may be made with PDS II suture of thickness 2/0 (0.3 mm diameter), and finally the distal capture element 32 with PDS II suture of thickness 2(0.5 mm).

As an alternative to assembling multiple capture elements, vascular filters may be made from a mesh of absorbable or non-absorbable composite material. Candidates for mesh capture systems include: polypropylene, such as C-QUR (Atrium Medical, Hudson, new hampshire); polypropylene encapsulated with polydioxanone as in PROCEED (Ethicon, Somerville, nj); polypropylene co-woven with polyglycolic acid fibers as in Bard Sepramesh IP composite (Davol corporation, Warwick, rhode island); polyethylene terephthalate as in Parietiex composites (Covidien, Mansfield, ma); and expanded polytetrafluoroethylene (w. gore & assoc. company, Flagstaff, arizona) for use in DUALAMESH.

For the loop element 2 of figures 1, 2 and 3 to support the capture element of an absorbable vascular filter and to keep the filter positioned within the blood vessel when expanded from the catheter, either an absorbable material as described above may be used, or a non-absorbable material may be used. The non-absorbable material acts essentially as a permanent scaffold, lasting well beyond the life of the absorbable capture element. This may be an important option in situations where the vessel needs to assist in maintaining patency. Both types of annular elements 2 may be fitted with barbs 79 (see fig. 2) to maintain filter positioning when deployed. Possible non-absorbable materials for constructing the annular element include: nickel-titanium alloy (Nitinol), Elgiloy (Elgiloy), cobalt-chromium-nickel-molybdenum alloy (Phynox), 316 stainless steel, MP35N alloy, titanium alloy, platinum alloy, niobium alloy, cobalt alloy, or tantalum wire.

Fig. 2a-2h illustrate another embodiment of an absorbable vascular filter, wherein absorbable capture elements 60-64 are mounted to a simple annular member 2, the annular member 2 being held against the vessel wall 70 by optional barbs 79. Here again, the annular element 2 can be made of an absorbable or non-absorbable material like that described above. Fig. 2b shows an enlarged cross-sectional view of the catch member assembly 65. Note that continuous degradation of the capture element can be achieved by varying the diameter of the absorbable material selected. For example, the inner capture element 60 may be PDS II 4/0 (0.15 mm diameter), resulting in time t ₁ Fastest absorption as shown in fig. 2 d; then, at time t in FIG. 2e ₂ The capture element 61 of (a), the capture element 61 being PDS II 3/0 (0.20 mm in diameter); then, at time t in FIG. 2f ₃ The capture element 62 of (a), the capture element 62 being PDS II 2/0 (0.30 mm in diameter); then, at time t in FIG. 2g ₄ The capture element 63 of (a), the capture element 63 being PDS II 0 (0.35 mm in diameter); and finally, at time t in fig. 2h ₅ Is used, the last capture element 64 is PDS II 1 (0.40 mm diameter). While these dimensions represent specific examples, any diameter between about 0.1mm to 0.7mm is sufficient. Overall, a gradual degradation protocol was purposefully designed after a 6 week prophylactic window for trauma and major surgical applications.

Referring to the embodiment shown in fig. 3a and 3b, a vascular filter 1 includes an outer annular stent 2 for supporting a plurality of collapsible filter capture elements (60-64) and maintaining vessel patency. The capture element is specifically designed to be collapsible for catheter-based installation and to avoid damage to the end organ. The support stent 2 shown is manufactured as an artificial vascular graft supported by a corrugated support structure 3. Such a vascular filter, which may consist of an absorbable filter capture element or a non-absorbable filter capture element, has various advantages over all conventional vascular filters, including permanent, temporary and optional IVC filters. Most importantly, the vascular filter is fabricated with a stent that, in addition to clearing the vessel, also serves as an annular mounting for the capture elements and avoids the endothelialization characteristics of barbed post metal filters. Thus, with metal IVC filters, the increase in incidence of DVT that can be observed due to the inherent vascular damage created by the metal struts may be avoided.

The ring-shaped stent element 2 in fig. 3a is used to support the capture element of the vascular filter in addition to keeping the blood vessel open and stabilizing the filter positioned in the blood vessel when expanded. A variety of stent types commonly used as thoracic prostheses may be utilized. Such a stent would include: gore TAG, Medtronic Talent and Valiant Systems, and Cook Zenith TX2 System. In particular, Gore TAG consists of an artificial vascular graft made using a fluoropolymer (expanded polytetrafluoroethylene (ePTFE) and fluorinated ethylene-propylene or FEP) in combination with a nitinol support structure. In addition, the stent component of the vascular filter may be fabricated with a single support structure (without the artificial vascular graft) utilizing nickel-titanium alloy (nitinol), cobalt-chromium-nickel alloy (elgiloy), cobalt-chromium-nickel-molybdenum alloy (Phynox), 316 stainless steel, MP35N alloy, titanium alloy, platinum alloy, niobium alloy, cobalt alloy, or tantalum wire.

Specific embodiments of absorbable vascular filters with continuous degradation were constructed, tested and evaluated with various polydioxanone sutures (thickness 3-0, 2-0, 0, 1) and shown in fig. 4 a. The filter features a higher density of mesh to capture smaller emboli than shown in fig. 2 b. Polydioxanone is a candidate polymer in terms of tensile retention and absorption properties demonstrated in wound approximation applications. A polyethylene flexible long life tube (Saint-Gobain Performance Plastics, Akron, ohio) similar to IVC with an inner diameter of 25.4mm was used for the vessel wall, with the polydioxanone processed into the various filter patterns shown.

Fig. 4a shows a net-like capture element purposely arranged for continuous or staged absorption, so as to avoid simultaneous detachment of the entire filter during absorption. Here, different diameters of strands of polydioxanone (thickness 3-0, 2-0, 0 and 1) were used to vary the time to complete absorption and in addition the expiry date. Since the absorbable polymer breaks at the stress points initially during absorption, the mesh filter is designed to break down into 8 pieces of length D/2 and 8 pieces of size D/4, where D is the inner diameter of the vessel. The goal is to disintegrate piece by piece, either in stages or continuously, to minimize free floating exposure of the polymer filter capture element during the cycle. Figure 4b is the same mesh design but with uniform thickness poly-p-dioxanone suture for comparison. Fig. 4c is a design of a radial filter similar to a conventional metal IVC filter, also showing variable diameter sutures for continuous absorption. Finally, fig. 4d is a radial design constructed with only poly-p-dioxanone of thickness 2-0.

The main endpoint (endpoint) of an absorbable polymer evaluated for vascular filter applications is the breaking load as a function of time. In addition to the absorbable filters depicted in fig. 4, some test units were fabricated with various absorbable polymer candidates for weekly destructive pull tests. The polymer properties were tested at weekly intervals using an ADMET eXpert 7601 tensile tester with MTESTQuattro software (Norwood, MA) to generate a stress-strain graph, in addition to a primary boundary point for breaking load, and several secondary boundary points: (i) maximum stress (tensile strength), (ii) maximum strain (% elongation at break), (iii) energy at break, and (iv) Young's modulus of elasticity. The ADMET machine was run at a crosshead speed of 3 cm/min and equipped with a high resolution 100lb load cell and a 2KN pneumatic gripper.

The candidate absorbable polymer (representing the capture element) that is sewn into the test unit is embedded in a closed circulatory system designed to mimic the physiology of the human heart. At weekly intervals, the system was shut down to extract each thickness and type of suture for destructive tensile testing. As a control, the same absorbable suture was immersed into a static buffer bath (StableTemp digital application bath, Cole-Parmer, Vernon Hill, illinois) which was maintained at 37 ℃ and tested once per week. The hypothesis is that: the enhanced thermodynamic performance of the circulatory system accelerates the absorption rate and tensile strength loss of the capture element.

The closed circulation system was constructed using thin walled 3/4 "PVC with an outer diameter of 26.7 mm that fits comfortably within flexible 25.4mm inner diameter polyethylene (Tygon) tubing simulating IVC. The systemic heart was a Harvard Apparatus large animal pulsatile blood pump (Holliston, MA) that simulated ventricular muscle action of the heart. The Harvard Apparatus blood pump was run nearby for 22 consecutive weeks (913K L pumped) with less preventive maintenance.

Heart rate was adjusted to 60bpm, stroke volume was between 60 and 70 ml, systolic/diastolic ratio of duration was 35%/65%, and systolic pressure varied from 120 mmhg (simulated condition of arterial filter to prevent brain and systemic embolism) to 5 mmhg (simulated condition of IVC filter to prevent PE).

Real-time measurements may be obtained from the upstream and downstream sensor manifolds. Sensors upstream of the absorbable filter under test conditions included digitized temperature, flow (liters/min), total flow (liters), and pressure (mmhg). Downstream instrumentation included real-time measurements of oxygen percentage, total dissolved solids (TDS in ppt), and pH. TDS monitoring was included to assess absorption byproducts that were less than 20 microns in size, while the downstream 80 micron in-line filter would capture fragments of the suture from the filter and test unit.

The four candidate absorbable vascular filters depicted in fig. 4 were installed in series along the upstream tube, while the 5 test units containing absorbable sutures for weekly destructive testing were installed in series along the downstream portion of the in vitro cardiac function testing system. A 288W heating tape (heating tape) with a thermostat was used to maintain 37 ℃ in the closed circulation system. Finally, the circulating fluid was phosphate buffered saline (Invitrogen, Carlsbad, CA) at pH 7.4, which had a similar electrolyte composition (profile) to human blood. The buffer was changed once a week in an effort to maintain a stable pH.

The absorption and tensile properties of the selected polymer are determined as a function of time until the competitive strength in both the circulation system and the control bath deteriorates. During each cycle, the circulating phosphate buffer was changed every week as the pH decreased from 7.4 to an average of 6.6. Due to better pH stability in a static environment, the buffer in the control bath was changed only once a month. When the oxygen averaged 30% and the TDS was 8.8ppt, the average flow was 4.7 liters/min.

The collage shown in FIG. 5 illustrates the staged or sequential absorption of a mesh absorbable filter design. Note that the filter began to disintegrate during cycle 13 and thereafter, in a phased manner, only 1 or 2 capture elements were lost per week continuously until complete disintegration within 22 weeks. The initial fragment detected at week 13 was located at a high stress point within the capture element. Since the apex of the capture element mounted to the annular support experiences twice the stress as compared to the base of the capture element, the initial fracture will occur at the apex. The capture elements form a loop (loop) extending from the vessel wall to the center of the filter, the capture elements being composed of poly-p-dioxanone with

thicknesses

1 and 0, the expiration date being 1 month 2012, while the shorter capture elements of one quarter of the extended diameter are composed of poly-p-dioxanone stitches with a thickness of 3-0, the expiration date being 1 month 2015. The expiration date proved to play a greater role in the rate of absorption than the suture diameter, since smaller diameter sutures fragmented within 17 weeks, compared to larger diameter sutures that fragmented within 13 weeks. The designed disintegration of 8 elements of length D/2 and 8 elements of length D/4 for the mesh filter actually produced smaller brittle fragments due to fragmentation and fragmentation. In fact, the largest filter element captured from the mesh design by the downstream 80um filter showed a largest fragment of 5mm x 0.3mm in size.

Perhaps the most important property considered for use in absorbable vascular filters is the strength retention curve of the absorbable polymer as shown in figure 6 for polydioxanone in the circulatory system in vitro. As shown, the polydioxanone initially exhibited a moderate intensity decrease, less than about 5% per week for the first 5 to 6 weeks, followed by a rapid decrease of approximately 20% per week. As a conservative generalization over the first 5 weeks in the cycle, the poly-p-dioxanone with a thickness of 1 maintains a strength of about 10kg, the poly-p-dioxanone with a thickness of 0 maintains a strength of 6 kg, the poly-p-dioxanone with a thickness of 2-0 maintains a strength of 4 kg, and the poly-p-dioxanone with a thickness of 4-0 maintains a strength of 1.5 kg. Similar results were obtained from the buffer bath control for the first 5 weeks. However, statistical differences were obtained at week 5 for thickness 0(P <0.014), at week 6 for thicknesses 2-0 and 1(P <0.021), and at week 7 for thicknesses 4-0: (P < 0.011).

The proposed filter design uses multiple strands as capture elements, so the embolic load is distributed to N strands. So, assuming even distribution, the net embolic load can be accommodated by the filter, which is N times the breaking load of each strand. Thus, a polydioxanone filter of 2-0 thickness fixed to an annular support with 8 capture elements will hold 32 kg of net embolic load.

Another method for achieving strength retention of the polymer is to use the percent strength retention as a function of time, as shown in fig. 7. In the graph, all coarse polydioxanone slowly lost intensity during the first 5 weeks and was then rapidly absorbed, with negligible intensity by week 10. Specifically, the polydioxanone in the extracorporeal circulation system maintained an average strength of thickness 2-0, a greater value of 88% at week 2, 85% at week 4, and 68% at week 6, compared to the results of 80% at

week

2, 70% at

week

4, and 60% at week 6 for an approximate application of Ethicon's in vivo animal tissue according to the Ethicon product literature.

For the polydioxanone used in the absorbable filter element as shown in FIG. 8, the Young's modulus of elasticity ranges from 1.0-2.3 GPA. Note that when the polydioxanone was treated with buffer, young's modulus initially decreased (the polymer became more elastic), reached a minimum at week 6, and then increased to about twice the original value. This increase in young's modulus of polydioxanone indicates that it has increased brittleness when it reaches zero terminal strength and is further observed during disintegration. This property may be advantageous for absorbable filter applications. For example, when polydioxanone reaches zero terminal intensity and disintegrates, it breaks apart and cleaves into smaller, fragile fragments, and is thus less potentially harmful to downstream organs. Further studies are needed to determine the exact size of the terminal fragment in vivo and to assess potential pulmonary micro-infarcts.

From the study of the in vitro absorbable filters, it was concluded that: poly-p-dioxanone appears to be a powerful candidate for use as an absorbable vascular filter, with sufficient strength retention to capture emboli for at least 6 weeks, and then be rapidly absorbed by hydrolysis to carbon dioxide and water in the next 16 weeks. In particular, polydioxanone with a thickness of 2-0 shows: during the cycle, a breaking load of 4 kg was conservatively maintained for each strand over the entire 5 week period.

Thus, a filter containing 8 capture elements would capture 32 kg of embolic load; or equivalently, the plug provides 1600kgmm of energy to break the filter, which is highly unlikely if the pressure in the IVC is only 5 mmhg (about 0.1 psi). In addition, the reticulated filter geometry, showing capture elements of different diameters and expiration dates, disintegrated in a continuous or staged manner, releasing 1 or 2 small and fragile filter pieces (less than 5mm x 0.3mm per piece) per week during the cycle from week 14 to week 22. Along with polydioxanone, which is approved and proven by the FDA to be allergy-free and pyrogen-free, the polydioxanone absorbable vascular filter of the deployment catheter may be a highly efficient and effective device for preventing pulmonary artery embolization.

One installation of an absorbable vascular filter is through intravenous insertion with a catheter, as shown in figures 9a-e, which requires only a local anesthetic. Here, as shown in fig. 9a, the filter is folded and compressed within a delivery catheter consisting of an outer sheath 71 and an internal applicator or stabilizer piston 73 on the central rod. For IVC filter deployment, a delivery catheter is inserted into the vasculature of the patient at a suitable location, such as the femoral vein or the internal jugular vein. The delivery catheter is then delivered through the vasculature, typically over a guidewire, until the desired deployment location is reached, often beneath the renal vein. The compressed filter 50 can then expand while sliding the outer sheath 71 in a proximal direction, pushing the stabilizer link and piston 72 in a distal direction (see fig. 9 b). Once the outer sheath 71 is withdrawn from the filter, the stabilizing piston 73 may also be retracted as shown in fig. 9 c. Thus, when the embolus 80 is released during a thrombotic event, the embolus is captured by the vascular filter and prevented from migrating to the heart and lungs, thereby preventing potentially fatal PE (see FIG. 9 d). After a preventive time window of desired filter use (in many applications, about 6 weeks), the filter is biologically absorbed, leaving no foreign material in the blood vessel, as shown in fig. 9 e.

An alternative embodiment of an absorbable vascular filter 1 is depicted in fig. 10a, with an integrated annular support 102 and capture basket 101. Here, the loop-shaped support 102 and capture basket 101 are braided or woven much like a radially expanding stent that can be compressed within a catheter as described above prior to deployment. Fig. 10b is a top view of the absorbable vascular filter showing the woven or braided form of capture basket 101. The braided form is shown to maintain a clear center 104 to allow insertion of a guidewire during catheter deployment. This particular embodiment is attractive in that the entire absorbable vascular filter (annular support and capture basket consisting of capture elements) can be made from a monofilament (as described below) with designed radial force to prevent filter migration as described below.

The integrated absorbable vascular filter shown in fig. 10a and 10b produces a radially expandable and compressible tubular filter exhibiting: with radial force depending on the size of the material chosen, angle phi of the crossing elements of the braid (b), (c), (d) and (d)

) And an amount exceeding the diameter of the sizing used. Specifically, the angle is important to establishing the radial force, which is depicted in FIG. 11 as

. When the angle is changed

At an angle close to 180 DEG

The greater the amount of radial force provided by the braid. In the usual case of the use of a magnetic tape,

is an obtuse angle, chosen between 90 and 180 °.

For illustration, fig. 11 shows a simple cylindrical braided braid (L-7, P-4) which is shown cut in the longitudinal direction and laid flat on the surface of the display looping needles 110(looping needles) and the braiding filaments 103. Considering the braid as a periodic series of sinusoids P τ (see the bolded portion of the braid of fig. 11), where P is the number of pins of the loop spanning one sinusoidal period and τ is the pin-to-pin spacing, an algorithm can be derived to ensure that: for a given set of parallel looped needles L that span equally the circumference of the intended diameter of the vascular filter, each needle will be looped once and the final loop ends at the origin.

The algorithm can be embodied by the table shown in Table 1 to indicate L, P and the angle of any desired number of circumferential rings (L)

The relationship between them. L/P represents the fraction of the sine wave spanned by each circle, and N represents the total number of turns around the circumference of the cylinder. Essentially, the weave creates sine waves of different phases by fixed increments until the final loop is complete, the final sine wave being expected to be in phase with the initial sine wave. The in-phase condition requires that the Nx (L/P) product will be an integer. Furthermore, to ensure that all needles are tied up by a loop, the first integer to be formed by the Nx (L/P) product must appear if N ═ P.

Table 1 relationship between weaving process parameters.

For example, L-7, P-4, the first integer appearing in the row corresponding to P-4 of table 1 is N-4, so that this combination of L, P and N will provide one successful knit in which all needles will be used (7 on top, 7 on bottom) and the last knit ends at the origin. It can be shown that for a successful weave L must be odd. Can further display the angle

Can be expressed as

2tan-1(P pi r/Ll), where r and l are the radius and length of the annular support 102 of the desired filter. For calculating in Table 1

R and l have values of 0.625 and 1.5 inches, respectively. Further, τ is easily calculated from the relation L τ ═ 2 π r or τ ═ 2 π r/L.

Fig. 12 shows another braiding combination, where L-7 and P-6. Note that the first integer appearing in the row of P6 in table 1 corresponds to N6, so the weave terminates successfully at the origin, with all L-needle loops tied up once. Further, fig. 12 illustrates a method for forming the catch basket 101 as the wire simply continues to extend over the loop support 102. As shown at the alternate loop tie points at the top of the loop support, the conical capture basket 101 is braided by sequentially interlocking loops from adjacent loops 105 and extending the loops to an apex 106. The tip rings from each extension 106 may be bonded together to form a conical capture basket as shown in fig. 10b, with an unobstructed central tip 104. Obviously, other weave patterns may be used, resulting in a pattern resolution sufficient to capture emboli of the desired size.

Although for simplicity only groups of 7 ringed needles were considered in the above description, for IVC, a more likely number effective for use with an absorbable vascular filter might be 17 or 19,

specifically, absorbable IVC filters with integrated annular support and capture basket were made from a single 10 foot synthetic filament (0.5mm diameter), as shown in fig. 13a and b, L-17, P-16,

102 °, l 1.5 ", r 0.625", and τ 0.23 ". By selecting a braid obtuse angle, 25% oversize diameter (to fit an IVC diameter of 1 ") and wide diameter filaments (0.5mm), the self-expanding IVC filter provides sufficient radial force to maintain IVC placement. Alternatively, the integrated absorbable vascular filter described above may be constructed with multiple connected filaments, although a single continuous filament may be preferred.

Referring to the embodiment depicted in fig. 14a and 14b, absorbable vascular filter 1 includes an outer annular member 120 (similar and/or identical to annular member 2 described above) for supporting and maintaining a plurality of filter capture elements 110 (e.g., similar and/or identical to the capture elements described above) in position within the blood vessel. The capture element 110 may be configured to capture or stop a substance flowing in a blood vessel for a limited time in time. Here, both the ring element 120 and the capture element 110 are laser cut from a generally circular absorbable polymer tube. This means that the ring member 120 and the capture member 110 form a unitary piece with no joints, seams, and/or other attachment points between the ring member 120 and the capture member 110. The monolith may be a substantially continuous structure having a smooth surface without protrusions that may be caused by joints, seams, and/or other attachment points. In some embodiments, the capture element 110 and the loop element 120 may be woven from a single strand or fiber, or cut from a sheet of material. For example, the filter may be cut from a sheet of absorbent polymer film and then formed into a tube shape. In some embodiments, the capture element 110 and the loop element 120 may be connected together as separate components to form the absorbable vascular filter 1.

The pattern of annular elements may be designed by finite element analysis and/or using other methods to generate a desired amount of radial force (or a given amount of radial force) for a given diameter (or diameters) upon deployment to ensure vena cava apposition (caval apposition). The proximal end 119 of the loop element 120 includes a wave feature 121 (e.g., similar and/or identical to a feature formed by braiding as described above), while the distal end 122 terminates at the capture element 110. In some embodiments, the loop elements have a lattice spacing (e.g., a lattice design that creates spaces between the members 117 of the loop element 120) that is less than the lattice spacing of the capture elements 110 (e.g., there is less space between the members 117 of the loop element 120 than between individual capture elements 110). In some embodiments, the lattice spacing of the annular elements 120 is configured such that the filter 1 produces a desired amount of radial force as described above. In some embodiments, the lattice spacing of capture elements 110 is configured such that targeted sized emboli or other particulates are captured by the filter without stopping the overall fluid flow through the blood vessel. In some embodiments, the members 117 of the ring element 120 and/or the capture element 110 may have a substantially rectangular cross-section, and/or other cross-sections that contribute to the radial force and/or capture characteristics of the filter 1. In some embodiments, the members 117 of the annular element 120 and/or the capture element 110 may have rounded, chamfered, and/or other shaped edges to facilitate fluid flow through the filter 1.

In some embodiments, the capture element comprises a loop 113 at the distal end 111, and the loop 113 may be secured with an absorbable coupler (e.g., a wire) 130 to form a filter apex at the distal end 141 of the filter 1. In some embodiments, individual loops 113 may be formed along the longitudinal axis of the corresponding capture element 110. In some embodiments, there may be one loop 113 per capture element 110. The ring 113 may be formed such that the open area 115 of the ring 113 faces the inner cavity of the filter 1. The ring 113 and/or open region 115 may have a generally circular shape and/or other shape (e.g., as described below) that facilitates closure of the distal end 141 of the filter 1.

In this example, absorbable coupling wire 130 may be a suture and/or other wire. In some embodiments, absorbable coupling wire 130 may be pre-threaded through loop 113 and/or otherwise threaded through loop 113 before the filter is implanted (or loaded) into a catheter for implantation. Absorbable coupling wire 130 may be configured to move between an expanded configuration 130a and a collapsed configuration 130 b. In the expanded configuration 130a, absorbable coupling wire 130 is configured to allow capture element 110 to remain in the open configuration (fig. 14a), without capturing (or only capturing very large) emboli. In the collapsed configuration 130b, the absorbable coupling wire 130 is configured to pull the distal ends 111 of the capture elements 110 toward each other to form a filter. In some embodiments, the absorbable coupling wire 130 may be configured to move from the expanded configuration 130a to a collapsed configuration in response to a pulling force applied to the end 129 of the wire 130. In some embodiments, filament 130 may include knot 127 and/or other tensioning mechanism that reduces the size of open end 135 of filament 130 (e.g., thereby moving ends 111 toward each other). For example, pulling on end 129 may cause slip knot 127 to tighten downward and close open end 135. Other tightening mechanisms are contemplated.

Referring to the embodiment shown in fig. 15a and 15b (where like reference numbers correspond to those in other figures described above), absorbable vascular filter 1 includes a ring member 120 for supporting and maintaining a plurality of filter capture elements 110 in position within the blood vessel. In this exemplary embodiment, capture element 110 includes a spline feature 151 at distal end 111 that can be fastened and/or otherwise coupled to a complementary spline receptacle 131a within an absorbable coupler (e.g., such as an endplate) 130 to form a filter apex. In some embodiments, spline feature 151 includes a shaped distal end 111. The distal end may be shaped to couple with a corresponding spline receptacle 131a such that the spline feature 151 does not release from the receptacle 131a when the filter 1 is deployed and/or in use.

In this example, the spline feature 151 comprises a substantially trapezoidal shape. The trapezoidal shape may have corresponding edges 153 extending in a circumferential direction from the width 155 of a given capture element 110. This makes the distal end 111 wider than the body 157 of the capture element 110. This also makes the distal end 159 of spline feature 151 wider than the portion of spline feature 151 extending from capture element 110.

In this example, corresponding spline receptacle 131a includes a trapezoidal channel configured to receive spline feature 151 (e.g., such that the components are pieced together like puzzle pieces). Receptacle 131a may be positioned around outer surface 161 of absorbable coupler 130 such that the channel has a narrow end 163 at a proximal side 165 of coupler 130 and extends axially along outer surface 161 of coupler 130 to a distal side 167 of coupler 130. In some embodiments, the channel becomes wider (e.g., to match the shape of spline feature 151) as it extends along outer surface 161, such that the channel has a wide end 169 at or near distal side 167. In some embodiments, the channel becomes wider as the channel extends toward the center of coupler 130 (e.g., to match the shape of spline feature 151) such that the channel has a broadside toward the center of coupler 130. These shapes may be configured to prevent separation of the spline feature 151 and the socket 131a during deployment and/or use of the filter 1. These shapes are not intended to be limiting. The spline features 151 and/or the receptacles 131 may have any shape and/or size that allows them to function as described herein.

In some embodiments, the end plate 130 can include a central bore 132 to receive a (e.g., cylindrical) radiopaque marker and/or guidewire. The central aperture 132 may be circular as shown, or have other shapes. In some embodiments, central aperture 132 may be located at or near the center and/or other locations of resorbable coupler 130. In some embodiments, the central aperture 132 may be sized such that insertion of the radiopaque marker causes the aperture 132 to stretch and exert a compressive force on the radiopaque marker. In some embodiments, the central bore 132 may be sized to pass a guidewire.

In some embodiments, capture element 110 can be configured to bend such that spline feature 151 passes through or near the axial centerline of filter 1 and couples to receptacle 131a (without blocking aperture 132) on the opposite side of coupler 130. When the individual capture elements are coupled to the coupler 130 in this manner, the forces from the individual capture elements (e.g., attempting to return to their cutting state from the direction of tube straightening) can act substantially uniformly around the coupler 130 (e.g., each pushing the coupler 130 toward the center of the filter) and prevent any individual spline feature from being released from its respective channel.

In some embodiments, the endplate may be attached to the capture element during manufacture, when the filter is assembled on the catheter for final deployment, and/or at other times prior to the implantation procedure.

Referring to the embodiment depicted in fig. 16a and 16b (where like reference numbers correspond to those in other figures described above), absorbable vascular filter 1 includes a ring member 120 for supporting and maintaining the position of a plurality of filter capture elements 110 within the blood vessel. The capture element includes a ring 171 at the distal end 111, and the ring 171 can be secured to a mating connecting shaft 133 within a recess 131b of the coupler (e.g., such as an endplate) 130 to form a filter apex.

In some embodiments, ring 171 can be similar and/or identical to ring 113 described above. In some embodiments, individual loops 171 may be formed along the longitudinal axis of the corresponding capture element 110. In some embodiments, there may be one loop 171 per capture element 110, or less than one loop per capture element 110, such as every other capture element 110 having a loop. The ring 171 may be formed such that the open area 173 of the ring 171 faces the inner cavity of the filter 1. The ring 171 and/or the open region 173 can have a generally circular shape and/or other shape configured to couple with the shaft 133 (e.g., as described below).

In some embodiments, the shaft 133 may be cylindrical and have a circular cross-sectional shape (as shown in fig. 16 a) and/or the shaft 133 may have other shapes (the shape of the open region 173 corresponds to the shape of the shaft 133). In some embodiments, the diameter (and/or other dimensions) of the shaft 133 may be the same as or slightly larger than the diameter (and/or other dimensions) of the corresponding open area 173, such that when both the ring 171 and the shaft 133 are coupled, the ring 171 forms a friction fit on the shaft 133. The shaft 133 extends from the abutment surface 183 of the concave portion 131 b. The abutment surface 183 is configured to receive a corresponding surface of the ring 171.

The concave portion 131b may be concave from the outer surface 161 of the coupler 130. In some embodiments, recessed portion 131b may have a depth (e.g., from outer surface 161 to abutment surface 183) that corresponds to the thickness of capture element 110 (e.g., the wall thickness of the tube from which filter 1 is cut). In some embodiments, the recessed portion 131b may have an open neck region 181, the open neck region 181 configured to facilitate coupling between the ring 171 and the shaft 133. The open neck region 181 can have a width corresponding to, for example, the width 155 of the capture element 110. The open neck region 181 can facilitate flush or near flush coupling between the capture element 110 and the coupler 130, and/or have other purposes.

In some embodiments, capture element 110 may be configured to bend such that ring 171 passes through or near the axial centerline of filter 1 and couples to shaft 133 (without blocking aperture 132) on the opposite side of coupler 130. When the individual capture elements are coupled to the coupler 130 in this manner, the forces from the individual capture elements (e.g., attempting to return to their cutting state from the direction of tube straightening) can act substantially uniformly around the coupler 130 (e.g., each pushing the coupler 130 toward the center of the filter) and prevent any individual ring from being released from its respective shaft (e.g., see fig. 16 b).

With reference to the embodiment depicted in fig. 17a and 17b (where like reference numerals correspond to those in other figures described above), the absorbable vascular filter 1 includes a ring member 120 for supporting and maintaining the position of a plurality of filter capture elements 110 within the blood vessel. In some embodiments, the capture element 110 includes a barb feature 190 at or near the distal end 111 of the capture element 110, the barb feature 190 being insertable into the through-hole 131c of the coupler (e.g., endplate) 130 to form a filter apex. In some embodiments, the bore 131c comprises a cylindrical through bore. In some embodiments, the axis of the through-hole 131c is aligned with the axis of the coupler 130, the aperture 132, and/or other features of the filter 1. In some embodiments, the bore 131c may have a tapered cross-section and/or other cross-section and/or be oriented along an axis that is not aligned with the axis of the coupler 130, the bore 132, and/or other features of the filter 1 (e.g., such that the bore 131c provides resistance to passage through the distal end 111 of the through-bore 131c and/or prevents the distal end 111 from exiting through the bore 131 c).

In some embodiments, an individual capture element 110 may have one barb feature 190, two barb features 190, three barb features 190, and/or other numbers of barb features. The example in fig. 17a and 17b shows two barb features 190 on each individual capture element 110, but this is not intended to be limiting. In some embodiments, the barb features 190 comprise

protrusions

191, 195 from the body 157 of the capture element 110. For example, the

projections

191, 195 may include pointed or near pointed ends and/or other dimensional shapes. In some embodiments, the

protrusions

191, 195 may protrude by the same amount. In some embodiments,

different protrusions

191, 195 on a given capture element 110 may protrude by different amounts. In some embodiments, the

protrusions

191, 195 can protrude by different amounts on different individual capture elements 110.

The protrusions 191 may protrude from the body 157 in a radial direction (e.g., around the circumference of the filter 1) and/or in other directions. In some embodiments, the protrusions 191 on different capture elements may protrude from the respective bodies 157 in the same radial direction. In some embodiments, the protrusions 191 on different capture elements may protrude from the respective bodies 157 in alternating radial directions and/or in other configurations. The projections 195 may project from the body 157 in an axial direction (e.g., along the long axis of the filter 1) and/or other directions. This may facilitate insertion of distal end 111 into bore 131c and/or for other purposes, for example.

In some embodiments, the barb features 190 can include channels 193 between the projections 191. Channel 193 can have a width and/or depth that facilitates coupling with, for example, coupler 130 and/or other coupling features. For example, the channel 193 can have a width corresponding to a thickness of the coupler 130 and/or have other dimensions. The channels 193 and/or projections 191 can be configured such that, as shown in fig. 17a and 17b, a first projection 191 on a given capture element 110 passes through a corresponding aperture 131c but a second projection 191 does not pass, such that the channels 193 between the projections 191 are positioned in the apertures 131c (e.g., as shown in fig. 17 b).

Referring to the embodiment depicted in fig. 18a and 18b (where like reference numbers correspond to those in other figures described above), absorbable vascular filter 1 includes a ring member 200 (similar and/or identical to ring members 2 and/or 120 described herein) for supporting and maintaining a plurality of filter capture elements 110 in position within the blood vessel. The proximal end of the ring element includes a wave feature 210 (similar and/or identical to wave feature 121 described herein), while the distal end 220 terminates in a loop 221 and/or other features configured to facilitate fixation of the proximal end of the absorbable capture element 110.

In some embodiments, as shown in fig. 18a, capture element 110 can be and/or include a capture filament. The capture filaments may comprise a plurality of individual filaments connected together, and/or the capture filaments may be formed from a continuous strand of material. A plurality of absorbable capture elements are connected to adjacent absorbable capture elements to create a capture basket 100 (e.g., similar and/or identical to capture basket 101 described above). The capture elements may intersect, wrap around each other, weave together, and/or otherwise couple. The apex of the filter 1 is formed into a ring by passing the capture element through a hole 310 in the endplate 300 (fig. 18b, e.g., similar and/or identical to endplate 130 described above). End 141 view 231 of filter 1 (without plate 300) is shown in fig. 18 a. As shown in view 231, the crossing and braiding of the capture filaments may form a flap-like structure configured to capture emboli and/or other particles flowing through the blood vessel. For example, the flap-like structures may more densely cover the lumen of the vessel near the center of the vessel, and less densely near the outside of the vessel.

In some embodiments, the capture wires are woven through the peripheral holes 310 of the endplate 300 to form the apices of the filter, while in other embodiments, the proximal ends of the capture wires may be secured at the peripheral hole locations 310. In some embodiments, the end plate includes a central bore 132 to accommodate cylindrical radiopaque markers and/or guidewires, and/or for other purposes.

Although the present invention has been described with reference to specific exemplary embodiments, it will be evident to those skilled in the art that various modifications and changes may be made to these embodiments without departing from the broader spirit and scope of the invention. The specification and drawings are, accordingly, to be regarded in an illustrative rather than a restrictive sense.

Reference to the literature

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Claims

1. An absorbable filter, comprising:

an absorbable annular element for attaching or securing the filter to a blood vessel;

a plurality of absorbable capture elements affixed to the ring-shaped member for capturing or preventing the flow of matter in a blood vessel for a limited time in time, wherein the ring-shaped member and the capture elements are each cut from a generally circular tube of absorbable material.

2. The filter of claim 1, wherein at least two absorbable capture elements have distally located loops securable with absorbable wires to form a generally conical capture basket.

3. The filter of claim 1, wherein at least two absorbable capture elements comprise distally located spline features securable to complementary spline receptacles within an endplate to form a generally conical capture basket.

4. The filter of claim 1, wherein the absorbable capture element comprises a distally located ring that is securable to a mating shaft within an endplate to form a generally conical capture basket.

5. The filter according to claim 1, wherein the absorbable capture element comprises a barb feature at a distal end insertable into a through-hole in an endplate to form a generally conical capture basket.

6. The filter of claim 1, wherein the absorbable capture element comprises a ring at a distal end that is securable to a mating shaft within an endplate to form a generally conical capture basket.

7. The filter of claim 1, wherein the subset of absorbable capture elements is selected to degrade continuously in time to avoid simultaneous substantial release of capture elements in the vessel over time.

8. The filter of claim 1, wherein the substantially circular tube is made of an absorbable material selected from the group consisting of polydioxanone, polytrimethylene carbonate, polylactide glycolide copolymers, polyglycolic acid, poly L lactic acid, poliglecaprone, polyglytone, and polylactic-co-glycolic acid.

9. The filter according to claim 1 wherein the annular element comprises anchoring elements or barbs for attachment to a blood vessel.

10. The filter according to claim 1, wherein the ring element and/or capture element comprises a bioactive surface for anticoagulation.

11. An absorbable filter, comprising:

a plurality of absorbable capture elements affixed to the ring-shaped element for capturing or preventing the flow of matter in a blood vessel for a limited time in time, wherein the ring-shaped element is cut from a substantially circular tube of absorbable material.

12. The filter of claim 11, wherein the plurality of absorbable capture elements are made of absorbable wires or sutures.

13. The filter of claim 12, wherein the plurality of absorbable capture elements connect with adjacent absorbable capture elements to create the capture basket.

14. The filter of claim 13, wherein the plurality of absorbable capture elements are directed to an endplate to form a generally conical capture basket.

15. The filter of claim 11, wherein the substantially circular tube and absorbable capture element are made of an absorbable material selected from the group consisting of polydioxanone, polytrimethylene carbonate, polylactide glycolide copolymers, polyglycolic acid, poly L lactic acid, poliglecaprone, polyglytone, and polylactic-co-glycolic acid.

16. The filter according to claim 11 wherein the annular element comprises anchoring elements or barbs for attachment to a blood vessel.

17. The filter according to claim 1, wherein the ring element and/or capture element comprises a bioactive surface for anticoagulation.

18. A method of delivering the filter of claims 1 and 11 using a delivery catheter, wherein the delivering comprises:

inserting the filter in compressed form into a delivery catheter to a desired location within a vessel; and

deploying the filter in expanded form at a desired location within the vessel; and is

The delivery catheter is then removed from the blood vessel.