ANCHORING SYSTEM FOR A CATHETER DELIVERED DEVICE

Abstract

The present disclosure relates to various anchoring systems for a catheter delivered device. In one instance the anchoring systems of the present disclosure are designed to be used in connection with a pulmonary artery implant device. In one embodiment, an anchoring system of the present disclosure comprises two anchoring ends, a distal end anchoring structure and a proximal end anchoring structure, where at least one of the distal or proximal anchoring structures has a clover-shaped structure formed by at least three lobes. In another embodiment, the distal anchoring structure includes an elongated and angled shape formed by wire material. In another embodiment, both the distal and proximal anchoring structures have a clover-shaped structure formed by at least three lobes.

Claims

1. An anchoring system for a vascular implant comprising: an implant having a distal end and a proximal end; and an anchoring system comprising a distal anchor and a proximal anchor, where the distal anchor is attached to the distal end of the implant and the proximal anchor is attached to the proximal end of the implant; wherein said distal anchor or said proximal anchor is formed from a flexible member configured to be placed into a retracted position for catheter delivery, and placed in an expanded position for placement within a vessel; wherein said at least one anchor is configured to position said implant against a vessel wall; and wherein at least one of the distal anchor or the proximal anchor has formed therein a lobe structure arranged in a manner where at least two lobes are located on either side of at least one central lobe so as to accomplish secure placement of the implant within a vessel.

2. The anchoring system of claim 1, wherein the proximal anchor has formed therein at least three lobe structures to accomplish secure placement of the implant upon implantation thereof by a catheter device.

3. The anchoring system of claim 1, wherein at least one lobe is configured to provide increased force on said vessel in order to mitigate movement of said implant after deployment.

4. The anchoring system of claim 1, wherein the anchoring system is designed for use in a pulmonary artery and the implant is designed to be read by an external reader unit placed against the chest of a patient in which the implant is located.

5. The anchoring assembly of claim 3, wherein said mitigated movement of said implant is proximal movement caused by contact with said catheter after implant deployment.

6. The anchoring assembly of claim 1, wherein said anchors are made of at least one type of extruded material selected from the following: nitinol, stainless steel, platinum, polished nitinol, low-inclusion nitinol, nitinol with a platinum core, and polymer.

7. The anchoring assembly of claim 1, wherein said lobe structure is a three lobe structure formed from a continuous wire and arranged in a manner wherein the two smaller lobes are located on either side of the central lobe wherein the central lobe is a larger lobe that has an overall length of at least 200 percent the length of the smaller lobes.

8. The anchoring assembly of claim 1, wherein said lobe structure is a three lobe structure formed from a continuous wire into a clover-shaped structure with at least two lobes located on either side of said central lobe.

9. The anchoring assembly of claim 1, wherein the two lobes are configured to provide a radial force against a vessel wall to prevent migration and rotation of the implant within the vessel.

10. The anchoring assembly of claim 1, wherein the lobe structure is configured to radially expand to abut against an inner wall of the vessel such that the at least two lobes expand outwardly from the implant while the central lobe extends upwardly from the implant.

11. An anchoring system for a vascular implant comprising: an implant having a distal end and a proximal end; and an anchoring system comprising at least one anchor formed from a flexible member configured to be placed into a retracted position for catheter delivery, and placed in an expanded position for placement within a vessel; wherein said at least one anchor is configured to position said implant against a vessel wall; and wherein the at least one anchor is formed as a lobe structure arranged in a manner where at least two lobes are located on either side of at least one central lobe so as to accomplish secure placement of the implant within a vessel.

12. The anchoring system of claim 11, wherein the anchoring system is designed for use in a pulmonary artery and the implant includes a sensor that is designed to be read from the chest of a patient in which the implant is located.

13. The anchoring assembly of claim 11, wherein said lobe structure is configured to translate force against the implant along the vessel axis to a radial force against the vessel wall that is provided by the two lobes.

14. The anchoring assembly of claim 11, wherein said central lobe has an overall length of at least 200 percent the length of said two side lobes.

15. The anchoring assembly of claim 11, wherein the lobe structure is a three lobe structure formed from a continuous wire into a clover-shaped structure with the at least two lobes located on either side of said central lobe.

16. The anchoring assembly of claim 11, wherein the two lobes are configured to provide a radial force against a vessel wall to prevent migration and rotation of the implant within the vessel.

17. The anchoring assembly of claim 11, wherein the lobe structure is a three lobe structure that is configured to radially expand to abut against an inner wall of the vessel such that the two lobes expand outwardly from the implant while the central lobe extends upwardly from the implant.

18. A method for inserting a biomedical sensor and anchoring system for securing same, the method comprising the steps of: (i) placing implant with an anchoring system onto an insertion catheter where the implant and anchoring system comprises: a housing having a distal end and a proximal end; and an anchoring system comprising at least one anchor, wherein the anchor is a clover-shaped structure formed from a continuous wire with at least two lobes located on either side of a central lobe; (ii) inserting the insertion catheter with the implant with an anchoring system into a desired blood vessel; and (iii) implanting the implant with an anchoring system into a desired blood vessel by releasing the implant with an anchoring system from the insertion catheter such that anchoring system secures placement of the implant in a desired location in the desired blood vessel.

19. The anchoring assembly of claim 11, wherein the lobe structure is a three lobe structure that is configured to radially expand to abut against an inner wall of the vessel such that said two lobes expand outwardly from the implant while the central lobe extends upwardly from the implant.

20. The method of claim 19, wherein the anchoring system is designed for use in a pulmonary artery and the implant is designed to be read by an external reader device held against the chest of a patient in which the implant is located.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0019] FIG. 1 is a perspective view of a known implant;

[0020] FIG. 2 is a photographic illustration of a sensor device or implant and an anchoring structure according to an embodiment of the present disclosure in a state ready for insertion into a patient and/or individual;

[0021] FIG. 3A is a photographic illustration of an embodiment of a sensor device or implant and an anchoring structure attached thereto in a state where the anchoring structure is in its expanded state as would be the case once placement occurs in a desired blood vessel (e.g., a pulmonary blood vessel);

[0022] FIG. 3B is a schematic illustration of an embodiment of a sensor device or implant and an anchoring structure attached thereto in a state where the anchoring structure is in an expanded state as would be the case once placement occurs in a desired blood vessel (e.g., a pulmonary blood vessel);

[0023] FIG. 4 is a photographic illustration of a sensor device or implant and an anchoring structure attached thereto in a state where the anchoring structure is in an expanded state in a 14 mm blood vessel (e.g., a pulmonary blood vessel);

[0024] FIG. 5A is an end view of an embodiment of a sensor device or implant with an anchor assembly including a distal anchor having an elongated and angled orientation and a proximal anchor having three lobes in accordance with the present disclosure;

[0025] FIG. 5B is a perspective view of the embodiment of the sensor device or implant and anchor assembly of FIG. 5A;

[0026] FIG. 6A is a photographic illustration of the a sensor device or implant of FIGS. 5A and 5B positioned within a model of a pulmonary artery;

[0027] FIG. 6B is a photographic illustration of the a sensor device or implant of FIGS. 5A and 5B positioned within a model of a pulmonary artery;

[0028] FIG. 7A is a photographic illustration of the a sensor device or implant of FIGS. 5A and 5B positioned within a model of a pulmonary artery;

[0029] FIG. 7B is a photographic illustration of the a sensor device or implant of FIGS. 5A and 5B positioned within a model of a pulmonary artery;

[0030] FIG. 8 is a schematic illustration of an embodiment of the present disclosure where a sensor device or implant and an anchoring structure attached thereto are in a state where the anchoring structure is in an expanded state.

[0031] FIG. 9 is a schematic illustration of various arteries of the human anatomy; and

[0032] FIG. 10 is a schematic cross-sectional view of a sensor device or implant positioned within the body of a patient and in communication with a reading device.

DETAILED DESCRIPTION

[0033] The present disclosure relates to various anchoring systems for a catheter delivered device. In one instance the anchoring systems of the present disclosure are designed to be used in connection with a pulmonary artery implant device. In one embodiment, an anchoring system of the present disclosure comprises two anchoring ends, a distal end anchoring structure and a proximal end anchoring structure, where at least one of the distal or proximal anchoring structures has a clover-shaped structure formed by at least three lobes. In another embodiment, the distal end anchoring structure has an elongated and angled orientation relative the implant body. In another embodiment, both the distal and proximal anchoring structures have a clover-shaped structure formed by at least three lobes.

[0034] FIG. 1 illustrates a prior art implant 10 that includes a housing 20 that includes an oblong, narrow, rectangular shape that extends along a housing axis 12, although the housing may have various shapes and geometry. The dimension of the housing 20 may be generally cuboid and may define a cavity therein. The housing side walls may be of specific dimensions and proportions to each other. For example, the housing may have four side walls 52, 54, 56, and 58, a top wall 60 and a bottom wall 62. The housing 20 may be made of a hermetic, strong, and biocompatible material, such as ceramic. The examples illustrate a cuboid housing, but other shapes and configurations may be used, such as cylindrical housings, prism-shaped housings, octagonal or hexagonal cross-sectioned housings, or the like. A sensor 40 is positioned along the top wall 60 and is attached to an antenna coil as well as other electronic components that may be positioned within the housing of the implant. The sensor 40 as well as the antenna coil and internal electronics may be positioned along a sensor axis 42 that extends generally normal relative to the implant 10 wherein the sensor 40 along the top surface 60 may be exposed to blood flow and pressure within the vessel once positioned within a patient. A distal anchor 70 and a proximal anchor 72 opposite the distal anchor may extend from the top surface of the implant 10. The anchors may fixate the implant 10 in a desired position in the body of the patient.

[0035] FIGS. 2-10 disclose various embodiments of an anchoring system according to the present disclosure. FIG. 2 depicts an embodiment of an anchoring assembly 100 of the present disclosure in a state ready for insertion into a patient and/or individual by, for example, a catheter in a minimally invasive procedure.

[0036] As illustrated by the embodiments in FIGS. 3A-3B, the anchoring assembly 100 comprises two anchoring ends, a distal anchoring structure 102 and a proximal anchoring structure 104, where at least one of the distal or proximal anchoring structures 102/104 has a clover-shaped structure formed by at least smaller two lobes 106 and 108 located on either side of a larger lobe 110. Located in between the distal anchoring structure 102 and the proximal anchoring structure 104 is a suitable implant sensor 112, such as the implant 10 illustrated by FIG. 1. FIG. 4 depicts the present invention in a state where the anchoring structure is in an expanded state in a 14 mm blood vessel, e.g., a pulmonary blood vessel.

[0037] The distal anchoring structure 102 and the proximal anchoring structure 104 may extend from a top surface 60 of the implant 10. Notably, the top surface 60 may include a sensor 40 as illustrated by FIG. 1. Alternatively, the implant 10 may include an actuator such as one that may be selected from among the following: neurostimulation, cardiac pacing, electrical stimulation, drug elution and the embodiments of the implant and anchoring system is not limited as to the type of sensor that may be utilized. Furthermore, the anchoring structures may comprise two individual shape set nitinol wires. As illustrated by FIGS. 3A-3B, the two wires comprise a distal wire and a proximal wire, where one anchor wire 102 is attached to the distal portion of a top surface 60 (spade shape, see FIGS. 3A-3B) of the implant 112 and the other anchor wire 104 is attached to the proximal portion of the top surface 60 (club shape, see FIGS. 3A-3B). Both anchors 102/104 can be collapsed down and attached to a delivery catheter via “release wires” or other mechanism like a shroud. The implant 112 and anchors 102/104 can be introduced into the human vasculature in the collapsed position and expanded to place the implant within a desired location of a vessel.

[0038] FIGS. 5A-5B illustrate an embodiment of an anchor assembly 200 with a distal anchoring structure 202 and a proximal anchoring structure 204. The distal anchoring structure includes a wire shaped with an elongated and angled orientation relative to the implant 212. The proximal anchoring structure 204 includes a wire that is shaped as a clover-shaped structure formed by at least smaller two lobes 206 and 208 located on either side of a larger lobe 210. Located in between the distal anchoring structure 202 and the proximal anchoring structure 204 is a suitable implant 212 such as one illustrated by FIG. 1.

[0039] The distal anchoring structure 202 and the proximal anchoring structure 204 may extend from a top surface 60 of the implant 212. Notably, the top surface 60 may include a sensor 40 that is attached to an antenna coil within the cavity of the implant housing as illustrated by FIG. 1. Furthermore, the anchoring systems of the present invention may comprise two individual shape set nitinol wires. As illustrated by FIGS. 5A-5B, the two wires comprise a distal wire and a proximal wire, where one anchor wire 202 is attached to the distal portion of a top surface 60 (elongated and angled, see FIGS. 5A-5B) of the implant 212 and the other anchor wire 204 is attached to the proximal portion of the top surface 60 (club shape, see FIGS. 5A-5B). Both anchors 202/204 can be collapsed down and attached to a delivery catheter via “release wires” or other mechanism. The implant 212 and anchors 202/204 can be introduced into the human vasculature in the collapsed position.

[0040] In the expanded position, the three-lobed proximal anchor 204 may radially expand to abut the inner wall of the vessel. Lobes 206 and 208 may expand outwardly from the implant 212 while lobe 210 may extend upwardly from the implant 212. These three lobes may radially abut against the inner wall of the vessel and may be arranged to abut against vessels of various sizes. The elongated and angled distal anchor 202 may include a slender configuration that may include a base portion 220 that may extend upwardly and slightly outwardly from the width of the implant 212 and an elongated portion 230 that may extend from the base portion 220 at an angle that includes a gradual taper until it ends at end portion 240. The elongated portion 230 may extend along elongated axis 232 wherein the elongated axis 232 may be positioned angularly relative to the sensor axis 42 as identified in FIG. 5A. The elongated axis 232 may intersect the sensor axis 42 at angle A wherein angle A may be about 20 degrees to about 40 degrees, or more particularly may be about 30 degrees. The elongated portion 230 may be over twice the length of the base portion 220. The slender elongated angle configuration may allow the distal anchor 202 to extend within a branch vessel of the pulmonary artery (“PA”) and may correctly position the implant 212 to allow the sensor axis 42 to extend towards the chest of a patient. Further, the configuration of the anchors 202, 204 may be arranged to allow the catheter or other delivery device to deploy the implant 212 with enough room to allow the catheter to be removed without bumping or rubbing against the implant 212 in which it may otherwise move or rotate the implant from its desired position.

[0041] It has been found that the elongated and angled configuration of the distal anchoring structure 202 may provide various benefits which may allow health clinicians to deploy the implant at an exact location and orientation with a reduced risk of translation or rotation once deployed. In one embodiment, the implant 212 with the distal anchor 202 may be placed in the right main trunk of the PA. As such, clinicians may be able to position the implant within the PA without having to rely on CT scans or quantitative angiography. Instead, in an embodiment, the clinician may reference the first apical branch of the right main trunk of the PA as an anatomical marker to identify where to position the implant 212 in which the elongated distal anchor 202 may be positioned. FIG. 9 is a labeled sketch of the right pulmonary artery wherein the apical branch is positioned adjacent the superior trunk of the right PA. It should be noted that a wide variety of pulmonary artery anatomy exists between patients. This includes differences in size and number of branches. Despite all this variation, the right PA main trunk has an anatomical feature that is present in nearly all patients in which the clinician may reference for implant placement: a sharp downturn from the right interlobar segment into the right posterior basal segment, see FIG. 9.

[0042] The elongated and angled distal anchoring structure 202 may allow the implant 212 to self-correct its position within the vessel. As illustrated by FIGS. 6A-6B and 7A-7B, the distal anchor 202 may be positioned to extend deep into the right posterior basal segment branch of the PA while the proximal anchor 204 may be positioned upstream in the interlobar PA segment. The distal anchor 202 may contact the vessel wall at or near the end portion 240 but it does not need to. Further, it does not need to contact along other radial positions along the base portion 220 or near the base portion 220 along the elongated portion 230, although in some patients it may do so. This may help prevent the implant from translating and rotating and allow the implant to be permanently located therein.

[0043] These anchors may allow for ease of implant placement as the distal anchor may be long enough so that when the catheter is removed, there is very little chance of migration into a side branch of the PA. The embodiment may also provide an anatomical landmark facilitating location of the target implant site, that may be easily identified by basic angiography and may allow a health clinician to align the implant such that is just distal from the superior trunk takeoff and proximal to the downturn of the PA. The disclosure may further prevent unwanted rotation due to: the spring force nature of the anchor, delivery system rubbing against the implant during removal, and patient coughing or other patient movement. The angle that the posterior basal makes with respect to the chest skin surface may ensure that the implant assumes an angle towards the chest that is optimal for RF communication. The angle may ensure that the implant faces the chest surface when the distal anchor 202 is placed into the posterior basal segment of the PA.

[0044] Further, if there is an unintentional deployment that is too distally positioned in the PA, the distal anchor 202 may still fit within the right posterior basal segment. If there is an unintentional deployment too proximally positioned, the distal anchor 202 may act to “pull” the implant 212 in the distal direction. In the event that the lobes of the proximal anchor 204 may migrate due to the spring force action, the downturn of the distal anchor 202 in the posterior basal segment may prevent it from translating as the elongated distal anchor will be generally prevented from “turning the corner” as the device moves proximally. Further, if there is migration of the implant 212 distally, the housing and proximal anchor 202 may form an angle that prohibits them from making the turn. As such, the implant 212 includes self-adjusting properties in this anatomical location within the pulmonary artery.

[0045] The two anchors may act to hold the bottom surface 62 of the implant 212 against the vessel wall with the sensor 40 and top surface 60 away from the vessel wall. Because the posterior basal segment is relatively thin, the implant may not sit any other way. The proximal anchor may hold the implant body against the vessel wall by itself without help from the distal anchor 204. The distal anchor may utilize its length relative to the implant to prevent rotation, by staying in the downturn. Additionally, it may prevent unintended interactions with other branches of the PA. The distal anchor 202 may not include loops and may be too straight and long to migrate into side branches easily.

[0046] In another embodiment as is illustrated in FIG. 8, an anchoring system 300 comprises two anchoring ends, a distal end anchoring structure 302 and a proximal end anchoring structure 304, where both the distal or proximal anchoring structures 302/304 have clover-shaped structures formed by at least two sets of smaller lobes 306 and 308 located on either side of a larger lobe 310. Located in between the distal end anchoring structure 302 and the proximal end anchoring structure 304 is a suitable implant sensor 312.

[0047] The anchoring structures of FIGS. 3A-3B, 5A-5B, and 8 are illustrated in the expanded position and it is understood that the anchors may be positioned in a collapsed or retracted position when attached to a catheter or other type of delivery device, such as that shown in FIG. 2. Notably, other anchor configurations and shapes may be implemented, including a different number of anchors (other than two); different locations of anchor attachment to the housing; anchors which attach to the housing at one point, or more than two points; anchors that extend under the housing, around it, or laterally to the sides. The anchors may be formed as loops which anchor the implant to body structures or within a vessel using spring force. The anchors may be made of nitinol, stainless steel, polymer, or any material which is biocompatible and extrudable. The anchors may be made of a combination of materials, such as nitinol with a platinum core. The anchors may be configured to fold down during the implantation procedure to allow easy ingress to the deployment location. The anchors may be configured to be tied down to a delivery system, such as a catheter, for minimally invasive ingress to the implant deployment site. The anchors may be designed to deploy from their tied-down configuration to their open configuration when an operator actuates a control on the proximal end of the delivery system. The control may include release wires that are pulled from the proximal end either directly or with help from a mechanical handle. The anchors may be coated with a material to increase lubricity.

[0048] The anchors may be positioned within the vessel at a desired location and caused to expand in the illustrated expanded positions as illustrated in FIGS. 4, 6A-B, and 7A-B. In these embodiments, as illustrated by FIG. 10, it may be desirable to position the implant 112, 212 within a vessel 540 with the top surface 60 and the sensor 40 aligned along the sensor axis 42 directed through the chest 510 of the patient and wherein the top surface 60 may be spaced from an inner wall 542 of the vessel 540. The configuration of the disclosed anchors may make this position possible as the aligned direction would allow the patient to utilize a reader device 530 to be positioned on or near the chest in proximity to the implant while also being directionally aligned with the top surface 60 and sensor 40. FIG. 10 schematically illustrates a cross sectional view of an implant 112, 212 positioned within a body 500 of a patient wherein the top surface 60 and sensor 40 thereon may be directed towards the center of a blood vessel 540. The implant 112, 212 may be located on the side of vessel 540 such that its distance from the wall of the chest 510, and hence from external reader 530, is minimized. The sensor 40 on the top surface 60 may be aligned along the sensor axis 42 that extends through the chest 510 and a user may allow the reader device 530 to be placed in alignment with the sensor axis 42 to wirelessly communicate with the implant through the chest 510 of the patient. The configuration of the anchor assemblies may allow for the implant to be placed in the desired location, so that a patient having the implant may be able to hold reader device 530 and take his own readings from the implant without the assistance of others. The above embodiment may also be applied to the implant of FIG. 8.

[0049] During the deployment of the implant 100/200/300, the anchors 202, 204 may be deployed sequentially when the release wires are retracted. Once an anchor is free and/or fully released, the anchor may utilize nitinol's super elastic property and instantly attempt to return to its initial shape set shape within the vessel. The distal anchor 202 may deploy first, pushing the distal end of the implant straight off the delivery catheter and onto the target position along the vessel wall. Next the proximal anchor 204 may deploy, pushing down the proximal end of the sensor body (the ‘implant’) 212 along the vessel wall target and engaging the two side lobes. Although stated in terms of implant 200, the above may be applied to any of the embodiments described herein, including implants 100 and 300.

[0050] Furthermore, the anchoring systems of the present invention comprise two individual shape set nitinol wires. As discussed above, the two wires comprise a distal wire and a proximal wire, where one anchor wire 102 is attached to the distal end (spade) of the implant 112 and the other anchor wire 104 is attached to the proximal end (club). Both anchors 102/104 can be collapsed down and attached to a delivery catheter via “release wires.” The implant sensor 112 and anchors 102/104 can be introduced into the human vasculature through a 14 Fr introducer. The anchors 102/104 are deployed sequentially when the release wires are retracted. Once an anchor is free and/or fully released, the anchor utilizes nitinol's super elastic property and instantly attempts to return to the initial shape set shape within the vessel. The distal anchor deploys first, pushing the distal end of the implant straight off the delivery catheter and onto the target position along the vessel wall. Next the proximal anchor deploys pushing down the proximal end of the sensor body along the vessel wall target and engaging the two side lobes which provide the most radial force and the largest deterrent to proximal migration and rotation. Although stated in terms of implant 100, the above may be applied to any of the embodiments described herein, including implants 200 and 300.

[0051] In one embodiment, the overall implant and anchoring structures are sized such that the anchoring system allows the implant to be placed in a proximal segment of the pulmonary artery. The proximal placement allows communication with device to occur from the chest instead of the back. The anchoring system of the present invention is designed to keep maximum vessel contact and remain stable over a large range of vessel sizes as compared to other devices known to those of skill in the art. The anchoring system of the present disclosure is designed to withstand any forces imposed by the retraction of or contact with the delivery catheter which is a well-documented procedure risk for devices designed with anchoring system failing to possess the various physical structures of the present disclosure. For example, if the insertion catheter snags the tip of the proximal anchor, the forces provided by the proximal anchor lobes increases to mitigate proximal movement.

[0052] As would be apparent to those of skill in the art, the use of the labels proximal and distal are for convenience sake and could be interchanged such that in the embodiment of FIGS. 3A-B, the distal end of the anchoring system 100 would have the clover-shaped structure formed by at least three lobes 106, 108 and 110. Such a change in orientation could be dictated by the environment and/or blood vessel in which the anchoring system and sensor device of the present disclosure are to be implanted in. The same may be applied to any of the embodiments described herein, including implants in FIGS. 5A-B and FIG. 8.

[0053] Regarding the nitinol wires utilized in the embodiments of the present disclosure, such wires are well known in the art and as such a detailed discussion herein is omitted for the sake of brevity. However, as is known to those of skill in the art, nitinol is formed from at least one nitinol alloys, where such alloys exhibit two closely related and unique properties: shape memory effect (SME) and superelasticity (SE; also called pseudoelasticity, PE). Shape memory is the ability of nitinol to undergo deformation at one temperature and then recover its original, un-deformed shape upon heating above its “transformation temperature”. Superelasticity occurs at a narrow temperature range just above its transformation temperature; in this case, no heating is necessary to cause the un-deformed shape to recover, and the material exhibits enormous elasticity, some 10 to 30 times that of ordinary metal. Given nitinol's biocompatibility it is well suited for use in biomedical devices and/or implants. Regarding the relationship between smaller lobes 106/108 and 206/208 and larger lobe 110 and 210 of the multi-lobed anchoring structures of the present disclosure, it should be noted that the larger lobe should have an overall length of at least 200 percent the length of the smaller lobes.

[0054] While in accordance with the patent statutes the best mode and certain embodiments of the disclosure have been set forth, the scope of the disclosure is not limited thereto, but rather by the scope of the attached. As such, other variants within the spirit and scope of this disclosure are possible and will present themselves to those skilled in the art.