Patent Publication Number: US-2021169631-A1

Title: Monofilament implants and systems for delivery thereof

Description:
RELATED APPLICATIONS 
     This application claims priority to U.S. Provisional Patent Application No. 61/754,264, filed Jan. 18, 2013, entitled “Monofilament Implants and Systems for Delivery Thereof”, the disclosure of which is incorporated herein by reference in its entirety. 
    
    
     FIELD OF THE DISCLOSURE 
     Embodiments of the present disclosure are directed generally to monofilament medical implants, and systems and methods for their delivery. Some embodiments of said systems may be automatic. Some embodiments are directed to embolic protection devices, and systems and methods for the delivery thereof. Some of the embodiments are directed at preventing embolic stroke. 
     BACKGROUND OF THE DISCLOSURE 
     Expandable implantable devices are often used for opening and closing passageways or orifices within the vascular, urinary, or gastrointestinal (GI) systems. Examples include vascular and GI stents for opening occlusions, left atrial appendage (LAA) and patent foramen ovale (PFO) occluding devices, and others. Such implantable devices typically consist of a scaffold that is introduced in a collapsed state and is expanded to a desired configuration at a target organ. 
     U.S. Provisional Patent Application 61/746,423, filed Dec. 27, 2012, to Yodfat and Shinar, assigned to Javelin Medical Ltd., discloses expandable devices and a method for implanting the devices within the body. Some of the embodiments of that disclosure are directed to devices made of super-elastic metal (e.g., nitinol) configured into a monofilament which is spatially bent and/or twisted (e.g., upon delivery). Such devices have two operating states—a contracted state (undeployed) and an expanded state (deployed). The devices may be implanted using a delivery system comprising (for example) a rigid needle having a preferred diameter of &lt;1 mm (3 French, 0.04″) and a sharp distal end. The devices may be preassembled within the needle in their stretched, substantially-linear, undeployed state and positioned at the needle&#39;s distal end. A pusher, in the form of an elongated rod, may also be preassembled within the needle, extending from proximally to the proximal end of the needle to the proximal end of the device. The implantation of the device may be performed by piercing the skin and underlying tissues and advancing the needle to the target organ under ultrasound guidance. At the desired location, the device may be exteriorized by retracting the needle with respect to the patient, pushing the pusher with respect to the patient, or both. This creates relative motion between the needle and the pusher, thereby exteriorizing the device. During the exteriorization process the device assumes its expanded deployed state within the target. 
     In a preferred embodiment, the device may be used as a filtering device (hereinafter “filtering device” or “embolic protection device”) for cardio-embolic stroke prevention. Such devices may be implanted at both carotid arteries to protect the brain from emboli originating in the heart, aorta, or other proximal large vessels. 
     The deployed state of the stroke prevention filtering device, according to those disclosed embodiments, may have the shape of a helical spring roughly occupying a spherical shell, with straight short ends extending from each side of the helix at the in the direction of the helix&#39;s principal axis of symmetry. Anchors for securing the filtering device to the carotid walls may reside at both ends. The anchors may also be made radiopaque or echogenic to provide visibility. When deployed, the device resides in transverse orientation within carotid artery lumen, the two device ends pierce the artery walls, and both anchors reside externally to lumen. 
     In the undeployed state, the device according to some embodiments, including anchors, resides within the lumen of the needle. The distal anchor is connected to the distal end of the helical spring and resides at distal end of the needle. The proximal anchor may be connected to the proximal end of the helical spring and reside closer to the proximal end of the needle than to the distal end of the device. After deployment, the anchors may self-expand to their deployed state. 
     Implantation, according to some embodiments, comprises insertion of the needle with the preassembled filtering device through the skin of the neck and transversally bisecting the carotid artery. Subsequently, the needle is retracted and the filtering device is exteriorized by the pusher. The filtering device assumes its deployed shape and is anchored externally to the carotid wall at both ends. 
     Experience shows that when the device is exteriorized from the needle, its distal end, at times, may rotate, bend, or twist. Therefore, whenever the device is exteriorized after its distal end is anchored in the carotid wall, this tendency to rotate, bend, or twist creates torque on the anchor. Accordingly, such torque might damage the tissue surrounding the anchor. Alternatively, the anchor may remain motionless but torsion may accumulate in the monofilament component of the device, thereby preventing it from assuming the desired deployed helical shape: The windings of the helix may distort and cross over. 
     Thus, there is a need for a helical filtering device that can be inserted into the carotid arteries in a safe and reproducible manner. 
     There is also a need to provide a helical filtering device that can transition from a helical shape to a substantially linear shape and back, without plastically deforming. 
     There is also a need for a helical filtering device (or any other monofilament device) in which torsion does not accumulate during deployment. 
     There is also a need for a helical filtering device (or any other monofilament device) comprising at least one bearing. 
     There is also a need for a system and method for safe implantation of a monofilament helical filtering device (or any other monofilament device) such that damage to the vessel walls and surrounding tissues is avoided. 
     There is also a need to provide a system for automatically implanting a filtering device (or any other monofilament device) in a safe and reproducible manner. 
     There is also a need to provide a system for automatically implanting a filtering device (or any other monofilament device) using a single hand. 
     There is also a need to provide a system for implanting a filtering device (or any other monofilament device), the system including housing and a user interface. 
     There is also a need for a system for implanting a filtering device (or any other monofilament device), the system including one or more sensors. Sensors may provide an indication of the needle position within the body or an indication of the deployment status or progression. 
     There is also a need for a system for implanting a filtering device (or any other monofilament device) that prevents the build-up of torsion in the filtering device by synchronizing device exteriorization and device rotation, bending, or twisting. 
     There is also a need for a system for implanting a filtering device (or any other monofilament device) that prevents the build-up of torsion in the filtering device by synchronizing device exteriorization and device rotation, bending, or twisting, wherein the system comprises a power supply, a motor. a controller, a driving mechanism, a sensor, and a user interface. 
     SUMMARY OF THE DISCLOSURE 
     In some embodiments, the filtering device is a monofilament made of a super-elastic alloy (i.e. nitinol), and has a circular cross section. In the deployed state the device is shaped as a helix (coil, spring, or their like) tracing a spherical shell, with two straight short monofilament segments extending from each helix end. The segments are oriented substantially collinear with the helix&#39;s principal axis of symmetry. 
     In some embodiments, each end-segment may comprise an end piece. Each end piece may comprise one or more of a radiopaque marker, an echogenic marker, an anchor, and/or a bearing. The bearing may have an axle, which may be integral with the monofilament, and housing. The axle may freely rotate within the housing, thereby eliminating the build-up of deleterious torsion during device deployment. 
     some embodiments, in the undeployed state, the helix-shaped monofilament is stretched to a substantially linear shape and assembled within the lumen of a needle. The distal end piece resides at the distal sharp end of the needle and proximal end piece resides closer to the proximal end of needle than the distal end of the device. A straight rod (“pusher”) is assembled within proximal side of needle; the pusher distal end is in contact with the proximal end of the filtering device. 
     In some embodiments, implantation comprises insertion of the needle, with the filtering device preassembled, through the neck skin, and transversally bisecting the carotid artery. Subsequently, retraction of needle and/or pusher advancement exteriorize the filtering device from needle may be according to the following sequence:
         1—The distal end piece is deployed externally to carotid lumen and anchored within surrounding tissue. The end piece may comprise a bearing enabling free rotation of the bearing axle around longitudinal axis, thereby avoiding the build-up of torsion in the monofilament.   2—The helical monofilament is deployed within the carotid lumen. During deployment the helix rotates roughly around its axis of symmetry, with distal end of the helix (axle) serving as a pivot point.   3—The proximal end piece is deployed externally to proximal side (close to skin) of the carotid lumen.       

     In some embodiments, torsion release may be achieved by concomitant needle retraction, needle rotation, and pusher advancement during filtering device exteriorization. 
     In some embodiments, implantation of the filtering device (or any other monofilament device) may be performed using a system that automatically synchronizes needle retraction, filtering device exteriorization, filtering device rotation, bending, or twisting (and corresponding torsion build-up prevention or release) during filtering device implantation. The system may comprise housing, a power supply, a motor, a control unit, and a driving mechanism. In some embodiments, the system comprises a reusable element. The needle and filtering device (disposables) may be pre-assembled before insertion and the needle is disposed after use. The driving mechanism may comprise gears that are engaged with proximal ends of the needle and the pusher. Upon operator activation, the controller operates a motor, synchronizes the needle and/or pusher rotation, and needle retraction. The system may include user interface components (operating buttons, screen, etc.), sensors (i.e. pressure sensor for safe positioning of needle end within artery), and indication means for providing better operator control during insertion. 
     Advantages of Some of the Embodiments 
     Embodiments according to the present disclosure have several important advantages over prior art: 
     Various embodiments of filtering devices according to the present disclosure may be safely inserted by providing a mechanism to prevent the build-up of torsion or to release accumulated torsion within the device. 
     Various embodiments of monofilament device implantation systems according to the present disclosure may provide safe and reproducible device implantation by automatically executing any combination of the following motions: needle retraction, needle advancement, device retraction, device advancement, device rotation, device bending, or device twisting. In particular, the build-up of torsion in the device may be prevented, and accumulated torsion may be released. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention may be better understood with reference to the accompanying drawings and subsequently provided detailed description: 
         FIG. 1A  depicts the undeployed state of a monofilament filtering device according to some embodiments of the present disclosure. 
         FIG. 1B  depicts the deployed (helical) state of the monofilament filtering device of  FIG. 1A . 
         FIG. 2A  depicts the undeployed state of a monofilament filtering device comprising end pieces according to some embodiments of the present disclosure. 
         FIG. 2B  depicts the undeployed state of a monofilament filtering device comprising end pieces according to some embodiments of the present disclosure. 
         FIG. 3A  depicts a schematic rendering of the undeployed state of an end piece according to some embodiments of the present disclosure. 
         FIG. 3B  depicts a schematic rendering of the deployed state of an end piece according to some embodiments of the present disclosure. 
         FIG. 4A  depicts the undeployed state of an end piece according to some embodiments of the present disclosure. 
         FIG. 4B  depicts the deployed state of an end piece according to some embodiments of the present disclosure. 
         FIG. 5A  depicts the undeployed state of another end piece according to some embodiments of the present disclosure. 
         FIG. 5B  depicts the deployed state of another end piece according to some embodiments of the present disclosure. 
         FIGS. 6A-6E  depict an apparatus and method according to some embodiments of the present disclosure, which are intended for implanting a monofilament filtering device according to some embodiments of the present disclosure. 
         FIG. 7  is a block diagram of an automatic system according to some embodiments of the present disclosure, which is intended for implanting a monofilament filtering device (or any other monofilament device) according to some embodiments of the present disclosure. 
         FIG. 8  is a schematic representation of an automatic system according to some embodiments of the present disclosure, which is intended for implanting a monofilament filtering device (or any other monofilament device) according to some embodiments of the present disclosure. 
         FIGS. 9A  depicts a perpendicular cross section of a needle of an automatic system of some embodiments of the present disclosure. 
         FIGS. 9B  depicts a perpendicular cross section of an end-piece of a filtering device (or any other monofilament device) according to the present disclosure. 
         FIGS. 10A and 10B  depict a monofilament filtering device according to some embodiments of the present disclosure in operation. 
     
    
    
     DETAILED DESCRIPTION OF SOME OF THE EMBODIMENTS 
     Reference is now made to  FIG. 1A , which depicts some embodiments of the undeployed state of a filtering device (embolic protection device) of the present disclosure. Filtering device  10 , configured to be implanted in a body vessel, can be a filament of cylindrical shape. However, cross sectional shapes other than circular are also possible. 
     In some embodiments, the length of the filament from which filtering device  10  is made may be greater than the diameter of the body vessel for which it is intended. Thus, if implanting the filtering device in a vein or an artery having a diameter of 7 mm, then the length of the filament may be, for example, in the range of about 7 to about 300 mm. 
     In some embodiments, the diameter of the filament from which filtering device  10  is made may be substantially less than its length. For implantation into a blood vessel, the filament diameter may be chosen of a size sufficient so as to not to cause blood coagulation. Therefore, the filament diameter, according to some embodiments, is less than about 0.5 mm, and more specifically less than about 0.2 mm, and even more specifically, less than about 0.15 mm. 
     In some embodiments, the undeployed state of device  10  may assume any shape that fits within the lumen of a tube having a length L and an inner diameter D such that L is much greater than D. (the terms “substantially linear” or “substantially straight” as used herein refer to all such shapes.) For example, length L can be in the range of about 10 to about 300 min, whereas the diameter D can be in the range of about 0.05 to about 0.7 mm. 
     In some embodiments, the undeployed state of device  10  may assume, for example. the shape of a substantially straight line. It may also assume a shape resembling a helix in which the pitch (that is, the vertical distance between consecutive windings) may be much larger than the helix diameter (that is, the diameter of the smallest cylinder in which the helix might fit). 
     Reference is now made to  FIG. 1B , which depicts an embodiment of the deployed state of a filtering device of the present disclosure. In the deployed state, filtering device  10  may assume the shape of a coil or a spring (helix). This coil shape may have windings or turns that vary in diameter. The windings may approximately trace the shape of a spherical shell. 
     The deployed length L′ of filtering device  10  may be greater than the diameter of the body vessel for which it is intended. Thus, if implanting the filtering device in a vein or an artery having a diameter of about 7 mm, then the deployed length L′ can be, for example, in the range of about 7 to about 20 mm. The deployed diameter D′ of filtering device  10  may be less than or approximately equal to the diameter of the target vessel at the implantation site. For example, if implanting the filtering device in a vein or an artery having a diameter of about 7 mm then the diameter D′ may be in the range of about 5 mm to about 8 mm. 
     In the deployed state, the “north-south” axis connecting distal end  11  and proximal end  12  of device  10  is substantially perpendicular to the plane approximately defined by some of the spring windings. The distal segment  13  and the proximal segment  14  of device  10  may be substantially collinear with the north-south axis. 
     The distal turn  15  of device  10  may reside in a plane containing the north-south axis. Likewise, the proximal turn  16  in device  10  may also reside in a plane containing the north-south axis. The two planes may, but do not have to, be one and the same. All of the remaining turns in device  10  may reside in planes that are approximately, but not necessarily exactly, perpendicular to the north-south axis. 
     Device  10  may be configured such that in the deployed state the radius of curvature at any point along its length is greater than or equal to a critical value R c . This critical value may be assigned such that the strain suffered at any point of device  10  is less than or equal to the critical strain required to bring about an elastic-to-plastic transformation. In this way device  10  may be able to suffer a transition from the deployed shape to the undeployed shape and back without substantial difference between the initial and final deployed shapes. For example, if the filament from which device  10  is made has a circular cross section having diameter d, and the material from which device  10  is made has critical strain E, then the critical value R c  may be given by R c =d/2ϵ. Therefore, if, for example, device  10  is made from super-elastic nitinol having critical strain ϵ of about 0.08, and the filament diameter d is about 0.15 mm, then the critical radius of curvature will be roughly about 0.94 mm. 
     The deployed state of device  10  may be configured to trap embolic material having typical size that is larger than the distance δ between consecutive windings. Whenever device  10  is configured to protect a patient from major embolic stroke, device  10  is made to trap emboli exceeding about 1-2 mm in size. In this case the distance δ is less than about 1.5 mm, and, more specifically, in the range of about 0.7 mm and about 1.5 mm. 
     Filtering device  10  may be configured to be relatively stiff or, in some embodiments, relatively flexible. Alternatively, filtering device  10  may be configured to assume any degree of flexibility. In the deployed shape, filtering device  10  may possess either a low spring constant or a high spring constant. Alternatively, in the deployed state, filtering device  10  may be configured to any value for its corresponding spring constant. 
     Filtering device  10 , according to some embodiments, can be configured as a solid filament. Alternatively, it can be configured as a tube having a hollow lumen, or as a tube having its ends closed-off, thereby leaving an elongated air-space inside filtering device  10 . Leaving an air-space inside filtering device  10  may have the advantage of making filtering device  10  more echogenic and therefore more highly visible by ultrasound imaging. Filtering device  10  may possess an echogenic marker or a radiopaque marker. 
     Filtering device  10  can be made out of any suitable biocompatible material, such as metal, plastic, or natural polymer. Suitable metals include shape-memory alloys and super-elastic alloys (nitinol). Suitable polymers may include shape memory polymers or super-elastic polymers. 
     A filtering device according to some embodiments of the present disclosure is substantially similar to filtering device  10 , except for one or more of the following differences: part or all of distal segment  13  may be lacking, part or all of distal turn  15  may be lacking, part or all of proximal segment  14  may be lacking, and part or all of proximal turn  16  may be lacking. For example, a filtering device substantially similar to  10  but lacking distal segment  13  and distal turn  15  may be particularly suitable for implantation through a single puncture in a target vessel. In such an embodiment, all device parts except perhaps for proximal segment  14  may lie entirely inside the vessel lumen or walls. Distal end  11  may comprise a a non-traumatic tip, or a short, sharp end configured to anchor in the vessel wall without breaching it completely. 
     Reference is now made to  FIGS. 2A and 2B , which respectively represent the undeployed and the deployed states of another embodiment of the filtering device of the present disclosure. Filtering device  20  is substantially similar to filtering device  10  of  FIGS. 1A and 1B : device  20  comprises a filament  21  that is substantially similar to the filament from which device  10  is made. However, device  20  may also comprise one or more of a first end piece  22  residing at one end of filament  21 , and a second end piece  23  residing at the opposite end of filament  21 . 
     In the undeployed state ( FIG. 2A ), filtering device  20 , including end-pieces  22  and  23 , may be configured to reside in the lumen of a hollow needle. Upon exteriorization from such a needle ( FIG. 2B ). filtering device  22  may assume a deployed shape substantially similar to that of filtering device  10 , and end-pieces  22  and  23  may assume a shape (but not required to) that is different from their shape in the undeployed state of device  20 . 
     Reference is now made to  FIG. 3A . which depicts a schematic representation of end piece  23  in the undeployed state according to some embodiments. End piece  23  may comprise one or more of the following: an anchor  31 , a radiopaque marker  32 , an echogenic marker  33 , and a bearing  34 . End piece  23  may also comprise a non-traumatic tip, such as a ball-shaped protrusion made of metal. 
     Anchor  31  may comprise any means known in the art for attaching a foreign body to living tissue. For example anchor  31  may comprise a roughened surface, one or more barbs, one or more micro-barbs, one or more hook, a hydrogel bulge configured to enlarge upon contact with an aqueous environment. or their likes. Anchor  31  may be configured to change its shape upon transition from the undeployed state to the deployed state of device  20  ( FIG. 3B ). Anchor  31  may comprise a biocompatible metal, a biocompatible polymer, a shape memory material, a super elastic material (e.g. super elastic nitinol) or any combination thereof. 
     Radiopaque marker  32  may comprise a biocompatible radiopaque material, such as gold or platinum. 
     Echogenic marker  33  may comprise a biocompatible echogenic material, such as tantalum. The marker  33  may comprise an echogenic coating comprising air micro-bubbles, cornerstone reflectors, or any other means known in the art to increase echogenicity. Upon transition from the undeployed state to the deployed state of device  20 , marker  33  may retain its shape. Alternatively, the shape of marker  33  may change upon transition from the undeployed to the deployed state. 
     Bearing  34  may comprise an axle  35  and a housing  36 . Axle  35  may be configured to freely rotate within housing  35 . Alternatively, axle  35  may be configured to rotate within housing  35  with any pre-specified degree of friction. Axle  35  may be rigidly connected to an end of filament  21 . Alternatively, axle  35  may be integral with an end of filament  21 . Housing  36  may be rigidly connected to anchor  31 . In this way, upon application of torque to axle  35 , the axle may rotate inside housing  36 , and housing  36  may remain substantially motionless with respect to the tissue in which it resides. 
     Bearing  34  may comprise any mechanism known in the art for constraining relative motion between the axle and the housing to only a desired motion. For example, bearing  34  may comprise a plain bearing, a bushing, a journal bearing, a sleeve bearing, a rifle bearing, a rolling-element bearing, a jewel bearing, and a flexure bearing. 
     End piece  22  may be the same as or different from end piece  23 . Similarly to end piece  23 , end piece  22  may comprise one or more of an anchor, a radiopaque marker, an echogenic marker, and a bearing. 
     We note that different components in each end piece need not be physically distinct: for example, the housing of the bearing can also serve as an anchor, the radiopaque marker and the echogenic marker may be one and the same, the bearing may serve to provide radiopacity or echogenicity, and so forth. To illustrate this point, reference is now made  FIGS. 4A and 4B , which represent an embodiment of end piece  23  according to the present disclosure, and to  FIGS. 5A and 5B , which represent an embodiment of end piece  22  according to the present disclosure. 
       FIG. 4A  depicts the undeployed state of a particular embodiment of end piece  23 , according to the present disclosure. End piece  23  may comprise an external cylinder  41 , prongs  45 , a proximal ring  42 , a distal ring  43 , a ball  44 , and axle  35 . External cylinder  41  and prongs  45  may be integral with each other. They may be made from a shape memory or super-elastic alloy, such as nitinol. Upon transition of device  20  from the undeployed to the deployed state, prongs  45  extend outwards, thereby anchoring end piece  23  in the tissue in which it is implanted. The proximal part of cylinder  41 , proximal ring  42 , and distal ring  43  may be rigidly connected to each other to form a bearing housing  36 . Rings  42  and  43  can each be made from a radiopaque and or echogenic material, such as god, platinum, or tantalum. The end of filament  21  may be rigidly connected to, and may be integral with, ball  44 , which can be made out of metal, a polymer, an alloy, a shape memory material, or a super elastic material. Together, filament end  21  and ball  44  provide a bearing axle  35 . The axle  35  is free to rotate within housing  36  more or less around the housing&#39;s principal axis of symmetry. However, in some embodiments, rings  42  and  43  substantially prevent all other relative motions of axle  35  with respect to housing  36 . Housing  36  and axle  35  together provide a bearing. 
       FIG. 5A  depicts the undeployed state of some embodiments of end piece  22 , according to the present disclosure. End piece  22  may comprise an external cylinder  51 , and prongs  52 , which may be integral with the cylinder. Both the prongs and the cylinder can be made from a shape memory or super-elastic material, such as nitinol. External cylinder  51  may be rigidly connected to the end of filament  21  using any known connection means known in the art, such as crimping, welding, soldering, gluing, and their likes. The external surface of cylinder  51  may be coated with an echogenic coating, or carry cornerstone reflectors. In this way, end piece  22  may comprise an anchor and an echogenic marker. However, the embodiment of end piece  22  presented in  FIGS. 5A and 5B  does not comprise a bearing. 
     Reference is now made to  FIGS. 6A-6E , which illustrate a system and a method according to some embodiments of the present disclosure for providing embolic protection according to some embodiments of the present disclosure. The system and method are particularly suitable for delivering a filtering device  20  comprising at least one end piece incorporating a bearing. The at least one end piece incorporating a bearing enables torsion in filament  21  of device  20  to be controllably released during device implantation, thereby providing for a controlled and robust implantation procedure. 
       FIG. 6A  depicts a system  60  configured to implant a filtering device  20  in a body vessel  61 . System  60  comprises a hollow needle  62 , a pusher  63 , and filtering device  20 . Taken together, the hollow needle and the pusher are a delivery device. Hollow needle  62  has a sharp end  63  configured to pierce skin  64 , subcutaneous tissue  65 , and body vessel  61  of a patient. Needle  62  may have a needle handle  66  located at its proximal end  67 . The needle handle  66  may be rigidly connected to needle  62 . Pusher  63  may have a pusher handle  68  located at its proximal end. 
     Hollow needle  62  may have a very small inner and outer diameter. For example, if the maximal collapsed diameter of undeployed filtering device  20  is about 200 to about 400 microns, the inner diameter of hollow needle  62  may be in the range of about 200 to about 900 microns, and the outer diameter of hollow needle  62  can be in the range of about 300 to about 1000 microns. More specifically, the inner diameter of hollow needle  62  may be in the range of about 200 to about 400 microns, and the outer diameter of needle  62  may be in the range of about 300 to about 600 microns. Thus, the puncture holes made by hollow needle  41  in a patient&#39;s tissue may be sufficiently small (about 400 to about 800 microns) as to be self-sealing. 
     Hollow needle  62  may be made out of any suitable biocompatible material, such as, for example, steel. Pusher  63  may also be made out of a metal such as steel. Handles  66  and  68  may be made out of plastic. 
     In the absence of external load, filtering device  20 , in some embodiments, assumes the deployed shape of  FIG. 2B . To transform device  20  to the undeployed state, it may be stretched by applying axial force at both its ends using a special jig (not shown). The stretched device may then be inserted into the lumen of needle  62  by sliding the needle over the stretched, undeployed device. Twisting device  20  before or during insertion into needle  62  is also possible. 
     Both filtering device  20  and pusher  63  may be slidable within the lumen of hollow needle  62 . Prior to deployment, filtering device  20  is located inside the lumen of needle  62  near its distal end  63 . The distal end  68  of pusher  63  is also located inside the lumen of hollow needle  62 . The distal end  68  of pusher  63  is in contact with the proximal end of end piece  22  of device  20 . After deployment, as depicted in  FIG. 6E , filtering device  20  may be exteriorized from hollow needle  62 , and the distal end of pusher  63  roughly coincides with distal end  63  of hollow needle  62 . 
     The implantation of filtering device  20  in body vessel  61  may proceed as follows. First, a physician determines that it is desirable to implant filtering device  20  in body vessel  61 . Under the guidance of a suitable imaging modality (not shown), such as, for example, ultrasound, high resolution ultrasound, or CT scanning, or without imaging guidance at all, the operator punctures skin  64  adjacent to vessel  61  using the sharp end  63  of needle  62 . Note that delivery device  60  is in the configuration depicted in  FIG. 6A , that is, with filtering device  20  housed near the distal end of hollow needle  62 , in its undeployed state. The operator then carefully advances delivery device  60  through the subcutaneous tissue, and transversely punctures vessel  61  at approximately diametrically-opposed sites  690  and  691 . The first puncture  690  of vessel  61  is made on its side closer to skin  64 , and the second puncture  691  is made on the diametrically-opposite side. The sharp end of needle  63  may then be advanced a few more millimeters interiorly into the patient, so that end piece  23  may be exterior to the lumen of vessel  61 . This situation is depicted in  FIG. 6A . 
     Next, the operator holds pusher  63  substantially motionless while retracting hollow needle  62  backwards, away from the patient. This can be done with the aid of handles  66  and  68 . In this way, end piece  23  of device  20  is exteriorized from needle  62 . It then assumes its deployed state in the tissue proximate second puncture  691 , thereby potentially anchoring the distal end of device  20  in the tissue. The needle may then be retracted until its distal end  63  roughly coincides with proximal puncture  690 . This situation is depicted in  FIG. 6B . 
     To exteriorize the remainder of device  20  from hollow needle  62 , the operator advances pusher  63  towards the distal end  63  of needle  62  while holding the needle still. As device  20  is exteriorized from the needle, it gradually assumes its deployed, spring-like shape-like shape. This situation is depicted in  FIG. 6C . 
     In some embodiments, exteriorizing device  20  may create torque along the principal axis of end-piece  23 . In such embodiments, it may be advantageous for end piece  23  to comprise a bearing  34 , thereby enabling the strain (torsion) pre-existing in filament  21  to release. This may also prevent torsion from building up during the exteriorization process. In such embodiments, the distal end of filament  21  rotates with end piece  23  as a pivot point while device  20  is exteriorized. The operator stops pushing the pusher once filament  21  is essentially exteriorized from needle  62  into the lumen of vessel  61 , and end piece  22  is situated, still inside the lumen of needle  62 , proximate its implantation site. The situation is then as depicted in  FIG. 6D . 
     In some embodiments, to complete the implantation procedure, the operator holds pusher  63  steady while retracting needle  62  over the pusher. This causes the end piece  22  to be exteriorized at its implantation site and assume its deployed shape. Once the entire device  20  is exteriorized and implanted in its deployed state, both needle  62  and pusher  63  are exteriorized from the patient&#39;s body. This completes the implantation procedure for some embodiments, as depicted in  FIG. 6E . Note that for some embodiments, because both the filtering device  20  and hollow needle  62  are of a diameter which is sufficiently small, all of the holes and the punctures made in body tissues during the procedure may be self-sealing. Therefore, the suturing or sealing of holes and punctures thus made is unnecessary. If it is determined that one or more additional filtering devices should be implanted in one or more additional implantation sites the procedure may be performed again, essentially as described above. 
     The system and implantation method corresponding to embodiment  10  of the filtering device are substantially similar to those described for delivery device  20  and its associated method of use, as described above. Therefore, a detailed description of delivery devices and implantation procedures corresponding to filtering device  10  is omitted. 
     In some embodiments, the implantation of filtering device  20  by means of system  60  in a body vessel may involve making a single puncture in the vessel wall, as opposed to two roughly diametrically opposed punctures: The operator makes a single proximal puncture in the vessel wall using needle  62 , or using distal end-piece  23 , the distal end of which may be sharp. The operator then places the distal tip of needle  62 , or the distal tip of end-piece  23 , in the lumen of the vessel. Subsequently, the operator advances device  20  into the vessel lumen by pushing pusher  63  while holding needle  62  steady, until only the proximal end-piece  22  remains inside needle  62 . Finally, exteriorization of device  20  from needle  62  is completed by, for example, retracting needle  62  while maintaining pusher  63  in place. Upon the completion of the exteriorization of device  20  from needle  62 , end piece  23  may be located anywhere inside the lumen of the vessel. For example, end piece  23  may appose the vessel wall. For example, end piece  23  may appose the vessel wall at a location roughly diametrically opposed to the puncture site. For example, end-piece  23  may partially or completely penetrate the vessel wall. For example, end-piece  23  may completely penetrate the vessel wall. Proximal end piece  22  may be located outside the lumen of the vessel, across the lumen of the vessel, or inside the lumen of the vessel. Typically, end piece  22  may comprise an anchor configured to prevent the migration of device  22  by securing it to the tissue of the vessel wall, or to tissue proximate the vessel wall. Upon completion of the exteriorization step, needle  62  and pusher  63  are withdrawn from the patient&#39;s body, and the implantation of device  20  is complete. 
     Reference is now made to  FIG. 7 , which provides a schematic block diagram of some embodiments according to the present disclosure of an automatic system for providing embolic protection according to some embodiments of the present disclosure. In some embodiments, mandatory blocks or components have solid outlines in  FIG. 7 , whereas optional blocks or components have dashed outlines. Solid lines connecting blocks represent information flow, power flow, or mechanical force transmission between blocks. Dashed lines connecting blocks represent optional information flow, power flow, or mechanical force transmission between blocks. Automatic system  70  may provide for a controlled and robust implantation of filtering device  20  (or filtering device  10 ), and for reduced inter-operator variability. 
     Accordingly, system  70  comprises a power supply  71 , a control unit  72 , one or more driving mechanism  73 , hollow needle  74 , and filtering device  20 . Optionally, system  70  may also comprise one or more sensors  75 . Taken together, power supply  71 , control unit  72 , one or more driving mechanism  73 , and hollow needle  74  comprise a delivery device. 
     The power supply  71 , control unit  72 , and one or more driving mechanism  73 , may reside in an external unit, which is external to the patient&#39;s body. Needle  74 , filtering device  20 , and optionally, one or more sensor  75  may be completely or partially located inside the patient&#39;s body during the device implantation procedure. The patient-external components may be housed in an ergonomic handle (not shown) and may or may not be sterile. The patient internal components may be sterile. System  70  may be completely disposable. System  70  may also comprise both reusable and disposable components. For example, the externally-residing components may be reusable, whereas the internally residing components may be disposable. 
     Power supply  71  may be an electrical or mechanical source of (free) energy. Power supply  71  may be a direct current source, such as a battery. Power supply  71  may also be an alternating current source. 
     Control unit  72  may comprise an input/output device, a central processing unit, a digital memory (all not shown), and any type of an analog or digital electronic controller (not shown). such as a computer processor programmed to cause any conceivable motion to filtering device  20 . For example, control unit  72 , by means of one or more driving mechanism  73 , may cause filtering device  20  to bend, twist, rotate, translate, or any combination of such motions. The controller may be an open loop controller, a closed loop controller, a proportional controller, a proportional integral derivative controller, or any other type of controller known in the art. Control unit  72  may store and implement any predetermined program of filtering device motions. Control unit  72  may optionally also receive inputs from one or more sensors  75 , and implement this information in governing the motion of filtering device  20 . 
     One or more driving mechanism  73  may comprise one or more motor and one or more transmission. The one or more transmission may couple the one or more motor to hollow needle  74  and/or filtering device  20 . The one or more driving mechanism  73  may be configured to rotate needle  74  (thereby causing some or all of filtering device  20  to rotate). Alternatively, one or more driving mechanism  73  may cause filtering device  20  to rotate by direct mechanical coupling between the driving mechanism and the filtering device. One or more driving mechanism  73  may be configured to cause needle  74  to advance or retract. One or more driving mechanism  73  may be configured to cause filtering device  20  to advance or retract within needle  74 , or to move together with the needle such that there is no relative motion between the filtering device and the needle. One or more driving mechanism  73  may be configured to cause filtering device  20  to be exteriorized from needle  74 . Mechanical coupling between one or more driving mechanism  73  and filtering device  20  may be made by means of a pusher, a rotating shaft, a spring, and their likes. 
     One or more driving mechanism  73  may comprise one or more motor. The motor or motors may be of the following types: a DC motor, a universal motor, an AC motor, a stepper motor, a permanent magnet motor, a brushed DC motor, a brushless DC motor, a switched reluctance motor, a coreless DC motor, a printed armature or pancake DC motor, an AC motor with sliding rotor, a synchronous electric motor, an induction motor, a doubly fed electric motor, a singly fed electric motor, and a torque motor. Signals, which may be generated by control unit  72  according to a predetermined program, or by a program optionally configured to receive signals from optional one or more sensor  75 , may be transmitted to one or more driving mechanism  73 . One or more driving mechanism  73  may then cause filtering device  20  to move in accordance with the predetermined program or sensor-signal-sensitive program, thereby achieving automatic device implantation. 
     Hollow needle  74  may be substantially similar to hollow needle  62  of  FIGS. 6A-6E . Therefore, we shall omit its detailed description here. Filtering device  20  may reside in its undeployed state inside the lumen of needle  74 . 
     One or more optional sensors  75  may comprise one or more of: a chemical sensor, a physical sensor, a mechanical sensor, a physiological senor, an electrophysiological sensor, and a pressure sensor. Optional one or more sensors  75  may be mounted on needle  74 . Optional one or more sensors  75  may provide information on whether the tip of needle  74  is within the lumen of a vessel, such as, for example, a blood vessel, or within the surrounding tissue. A pressure sensor may serve this function because the blood pressure (that is, the pressure inside the lumen of a blood vessel) is different from the pressure in the surrounding tissue. This information may provide extra safety: for example, control system  72  may be preprogrammed to prevent the exteriorization of an end unit of filtering device  20  unless the pressure sensed is within ranges typical for blood pressure in the target vessel. 
     Optional one or more sensors  75  may sense the stage of the heart cycle. As it might be advantageous to exteriorize the filtering device  20  only when the target vessel is in a relaxed state (corresponding to a heart diastole), optional one or more sensor  75  may comprise an electro-cardiogram (ECG) sensor. 
     In some embodiments, the implantation of filtering device  20  by means of automatic system  70  in a body vessel may proceed as follows. First, a physician determines that it is desirable to implant filtering device  20  in the body vessel. Under the guidance of a suitable imaging modality (not shown), such as, for example, ultrasound, high resolution ultrasound, or CT scanning, or without imaging guidance at all, the operator punctures the skin adjacent to the vessel  61  using the sharp end of needle  74 . The operator then carefully advances delivery device  70  through the subcutaneous tissue, and transversely punctures the vessel at approximately diametrically-opposed sites. The sharp end of needle  74  may then be advanced a few more millimeters interiorly into the patient, so that end piece  23  is exterior to the lumen of the vessel. Once this positioning is achieved, the operator instructs control unit  72  to execute a predetermined program (which optionally depends on inputs from one or more sensor  75 ), which causes device  20  to be properly exteriorized, such that the end pieces are external to the vessel lumen and the filament of device  20  is properly arranged within the lumen. Once the device  20  is properly exteriorized, the operator extracts system  70  from the patient&#39;s body. 
     In some embodiments, the implantation of filtering device  20  by means of automatic system  70  in a body vessel may proceed as in the previous paragraph until the step in which the operator punctures the body vessel. Instead of making two substantially diametrically-opposed punctures in the vessel wall, the operator makes a single puncture in the vessel wall using needle  74 , or using distal end-piece  23 . The operator then places the distal tip of needle  74 , or the distal tip of end-piece  23 , in the lumen of the vessel. Subsequently, the operator instructs control unit  72  to execute a predetermined program (which optionally depends on inputs from one or more sensor  75 ), which causes device  20  to be properly exteriorized. Upon the completion of the exteriorization step, end piece  23  may be located anywhere inside the lumen of the vessel. For example, end piece  23  may appose the vessel wall. For example, end piece  23  may appose the vessel wall at a location roughly diametrically opposed to the puncture site. For example, end-piece  23  may partially or completely penetrate the vessel wall. For example, end-piece  23  may completely penetrate the vessel wall. For example, proximal end piece  22  may be located outside the lumen of the vessel, across the lumen of the vessel, or inside the lumen of the vessel. End piece  22  may comprise an anchor configured to prevent the migration of device  22  by securing it to the tissue of the vessel wall, or to tissue proximate the vessel wall. 
     In some embodiments, system  70  may cause device  20  to rotate, bend, or twist in order to prevent the build-up of torsion during device exteriorization. In some embodiments, system  70  may cause device  20  to rotate, bend, or twist in order to release torsion accumulated in the device. 
     Reference is now made to  FIG. 8 , which schematically represents some embodiments of a system  80  for providing embolic protection. System  80  comprises a patient-external unit  81  and a patient-internal unit  82 . Patient external unit  81  may be disposable or reusable. Patient-internal unit  82  may be disposable. Device  80  may be sterilizable using means known in the art, such as ETO sterilization, gamma ray sterilization, and their likes. Patient-internal unit  82  may reversibly connect and disconnect from patient-external unit  81  whenever unit  81  is reusable. Such reversible connection means may comprise any known reversible connections means such as, for example, a screw. 
     Patient-external unit  81  may comprise a power supply  810 , a control unit  811 , driving mechanisms  819 ,  832 , and  833 , gear ring  815 , and bearing  816 , all of which may be housed in housing  834 . Patient-internal unit  82  may comprise needle  831  and filtering device  20 . Filtering device  20  may reside in its undeployed, substantially linear state within the lumen of needle  831 . 
     Power supply  810  and control unit  811  may be substantially similar to power supply  71  and control unit  72 , respectively. Therefore, their detailed description is omitted here. 
     Driving mechanism  833  may configured to advance or retract needle  831  with respect to housing  834 . Driving mechanism  832  is configured to rotate needle  831 . Driving mechanism  819  is configured to advance or retract device  20  with respect to housing  834 . Bearing  816  is configured to allow needle  831  to rotate with respect to housing  834 . Gear ring  815  may be configured to couple needle  831  to driving mechanisms  832  and  833 . Gear ring  815  may attach to the proximal end of needle  831  around the circumference of needle  831 . 
     Driving mechanism  833  may comprise a motor  818  and a shaft  817 . Motor  818  may be substantially similar to the one or more motors comprised in one or more driving mechanism  73 . Therefore, a detailed description of motor  818  is omitted here. Shaft  817  may be configured to transmit the linear (advancement/retraction) motion generated by motor  818  to gear ring  815 , thereby advancing or retracting gear wheel  815  (and needle  831  to which gear wheel  815  may be rigidly connected) with respect to housing  834 . 
     Gear wheel  815  may be connected to shaft  817  in the following way: gear wheel  815  may comprise a circular groove (not shown) at its proximal end, and the tip of shaft  817  may be inserted in this groove. The shape of the groove may be made such that its opening to the proximal face of gear wheel  815  may be narrower than its interior. Similarly shaft  817  may comprise a bulb at its distal tip, whose maximal width is larger than the size of the opening of the groove. Thus, whenever the tip of shaft  817  is inserted in the groove, linear motion of shaft  817  is translated to likewise linear motion of gear wheel  815  (and needle  831 ) by the coupling between the shaft and the groove. However, gear wheel  815  is free to rotate without hindrance from shaft  817  because the tip of shaft  817  is free to slide within the channel of the groove. 
     Driving mechanism  832  may comprise a motor  812 , a shaft  813 , and a gear wheel  814 . Motor  812  may be substantially similar to the one or more of the motors comprised in one or more driving mechanism  73 . Therefore, a detailed description of motor  812  is omitted here. Shaft  832  is configured to transmit the rotary motion generated by motor  812  to gear wheel  814 . 
     Gear ring  815  and gear wheel  814  may be connected by means of interlocking gear teeth. Therefore, the rotation of gear wheel  814  is translated to rotation of gear ring  815 . Because gear ring  815  is rigidly connected to needle  831 , rotation of gear wheel  814  translates to rotation of needle  831 . 
     Gear wheel  814  may be configured to slide with respect to gear ring  815  in the linear (advancement/retraction) direction. In this way, rotational coupling between gear wheel  814  and gear ring  815  is preserved regardless of the linear position of bear ring  815  (and needle  831 ). Needle  831  may be free to rotate with respect to housing  834  by means of bearing  816 . 
     Driving mechanism  819  may comprise a motor  835  and a push wire  822 . Motor  835 , which may be of any of the types comprised by one or more driving mechanism  73 , may comprise a stator  820  and a rotor  821 . The proximal portion of flexible push wire  822  may be rolled around rotor  821 . The distal end of push wire  822 , which may reside in the lumen of needle  831 , may be coupled to the proximal end of device  20 . The coupling may be reversible. For example, disconnection of the coupling may be realized using mechanical or electrical means as known in the art, such as, electrolysis. 
     Whenever motor  835  is configured to cause rotor  821  to rotate in the counterclockwise direction, push wire  822  may then advance relative to needle  831 , and device  20  caused to advance relative to the needle. Whenever motor  835  is made to cause rotor  821  to rotate in the clockwise direction, push wire  822  is retracted with respect to needle  831 . This may or may not cause device  20  to also retract with respect to the needle, depending on the type of coupling between push wire  822  and the proximal part of device  20 . 
     Whenever needle  831  rotates with respect to housing  834 , the rotational motion is transmitted to device  20 . The transmission of rotational motion between the needle and the device may be realized by friction between the interior walls of the needle and the device. Alternatively, the inner cross-section of the needle may have a noncircular shape ( FIG. 9A ), and one or more of the end-pieces  22  and  23  may have a perpendicular cross-sectional shape that interlocks with the cross sectional shape of the needle lumen ( FIG. 9B ). 
     In operation, power supply  810  provides electrical or mechanical power to control unit  811 . Control unit  811  transmits power and/or signals to driving mechanisms  832 ,  833 , and  81  according to a predetermined program stored in the control unit, or by instructions from the operator that are transmitted to the control unit via its man machine interface. Any combination of linear and/or rotational motions of needle  831  and/or device  20  with respect to external housing  834  may be implemented. 
     In some embodiments, the implantation of filtering device  20  by means of automatic system  80  in a body vessel may proceed as follows. First, a physician determines that it is desirable to implant filtering device  20  in the body vessel. Under the guidance of a suitable imaging modality (not shown), such as, for example, ultrasound, high resolution ultrasound, or CT scanning, or without imaging guidance at all, the operator punctures the skin adjacent to the vessel using the sharp end of needle  831 . The operator then carefully advances system  80  through the subcutaneous tissue, and transversely punctures the vessel at approximately diametrically-opposed sites. The sharp end of needle  831  may then be advanced a few more millimeters interiorly into the patient, so that end piece  23  is exterior to the lumen of the vessel. Once this positioning is achieved, the operator instructs control unit  811  to execute a predetermined program (which optionally depends on inputs from one or more sensor), which causes device  20  to be properly exteriorized, such that the end pieces are external to the vessel lumen and the filament of device  20  is properly arranged within the lumen. Once the device  20  is properly exteriorized, the operator extracts system  80  from the patient&#39;s body. 
     In some embodiments, the implantation of filtering device  20  by means of automatic system  80  in a body vessel may proceed as in the previous paragraph until the step in which the operator punctures the body vessel. Instead of making two substantially diametrically-opposed punctures in the vessel wall, the operator makes a single puncture in the vessel wall using needle  831 , or using distal end-piece  23 , which may comprise a sharp tip. The operator the places the distal tip of needle  831 , or the distal tip of end-piece  23 , in the lumen of the vessel. The operator then instructs control unit  810  to execute a predetermined program (which optionally depends on inputs from one or more sensor), which causes device  20  to be properly exteriorized. Upon the completion of the exteriorization step, end piece  23  may be located anywhere inside the lumen of the vessel. For example, end piece  23  may appose the vessel wall. For example, end piece  23  may appose the vessel wall at a location roughly diametrically opposed to the puncture site. For example, end-piece  23  may partially or completely penetrate the vessel wall. For example, end-piece  23  may completely penetrate the vessel wall. For example, proximal end piece  22  may be located outside the lumen of the vessel, across the lumen of the vessel, or inside the lumen of the vessel. Typically, end piece  22  may comprise an anchor configured to prevent the migration of device  22  by securing it to the tissue of the vessel wall, or to tissue proximate the vessel wall. 
     In some embodiments, system  80  may cause device  20  to rotate, bend, or twist in order to prevent the build-up of torsion during device exteriorization. In some embodiments, system  80  may cause device  20  to rotate, bend, or twist in order to release torsion accumulated in the device. 
     In some embodiments, a system similar to  80  is feasible, in which the needle does not rotate but device  20  is free to rotate within the needle. Such a delivery device need not have a bearing  816  and a driving mechanism  832 . Instead, a different driving mechanism is configured to rotate device  20  inside the lumen of needle  831  by rotating pusher  822  inside the needle and rotationally coupling the pusher to device  20 . 
     Systems  70  and/or  80  may be used to deliver all monofilament implants that have a substantially linear undeployed state and a bent and/or twisted deployed state. Such devices, including vessel occluders, stents, drug delivery platforms, radiation delivery platforms, PFO occluders, Left Atrial Appendage Occluders, and their likes, are described in Provisional Patent Application 61/708,273 to Yodfat and Shinar, which is incorporated herein by reference. All monofilament device embodiments described in 61/653,676 and also in Provisional Patent Applications 61/693,979 and 61/746,423 to Shinar and Yodfat, may possess end-pieces such as  22  and  23  of the present Provisional Application. 
     Reference is now made to  FIGS. 10A and 10B , which depict a side view and a cross-sectional view of device  20  in operation. Device  20  is implanted in body vessel  80  such that its north-south axis is substantially perpendicular to the principal axis of symmetry of vessel  80 . Embolus  81  may be filtered by device  20  because the spacing δ between consecutive windings of the device is smaller than the size of the embolus. The embolus may thus filter by size exclusion. 
     It is understood that monofilament filtering devices according to some embodiments of the present disclosure are possible in which, in the deployed state, each end of the filament may either reside inside the lumen of a body vessel, in the wall of the vessel, or exteriorly to the wall of the vessel. For example, a device in which the proximal end resides entirely within the lumen and the distal end resides exteriorly to the vessel is possible. A device in which both ends reside in the vessel wall without penetrating the vessel&#39;s exterior wall is possible. In this way, for each end all different combinations of penetration depths (in-lumen, in-wall, exterior to wall) are possible. 
     It is understood that monofilament filtering devices according to some embodiments of the present disclosure are possible in which, in the deployed state, the proximal end of the monofilament extends exteriorly from the patient&#39;s skin, or is implanted subcutaneously immediately below the patient&#39;s skin. Such devices are particularly suited for temporary usage, in which it is desired to retrieve the device shortly after a temporary embolus-enticing cause, such as surgery or minimally-invasive procedure, is removed. 
     Although the embodiments of the present disclosure have been herein shown and described in what is conceived to be the most practical way, it is recognized that departures can be made from one and/or another of the disclosed embodiments and are within the scope of the present disclosure, which is not to be limited to the details described herein. The following exemplary claims aid in illustrating an exemplary scope of at least some of the embodiments disclosed herein.