Abstract:
Medical filament delivery apparatus includes a feed chamber to which can be fed filamentary material from a store of filamentary material. The apparatus is designed to feed filamentary material through a catheter into a patient, for example into an aneurysm. The apparatus includes a feed tube assembly having a feed tube with a slot at its distal end. A distal end of the filamentary material can be held within the slot to ensure accurate positioning of the distal end of the filamentary material into the drive assembly. The apparatus provides for severing of the distal end of the filamentary material once the feed tube assembly has been inserted into the drive assembly, thereby ensuring reliable positioning of the filamentary material into the drive assembly. More delicate filamentary material can be handled compared to prior art arrangements.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of priority under 35 U.S.C. §119(a) to Great Britain Patent Application No. GB 1603633.7, filed Mar. 2, 2016, which is hereby incorporated by reference in its entirety. 
       TECHNICAL FIELD 
       [0002]    The present invention relates to apparatus for delivering filamentary material into a patient and to a device for guiding filamentary material through such apparatus. The filamentary material can be used to fill an aneurysm, occlude a vessel or other organ, as well as for other medical procedures. 
       BACKGROUND ART 
       [0003]    There are several medical conditions which can benefit from implantation into a patient of a filler material, an embolization coil or other device, whether temporary or permanent. Examples include the closure of blood vessels or other lumens. One condition for which such procedures can be particularly useful is in the treatment of aneurysms, where a part of a vessel wall weakens and expands outwardly to create an enlarged zone of the vessel, often having the form of a sac. This vessel expansion occurs as a result of blood pressure and tends to continue due to further and progressive weakening of the vessel wall. If left untreated, persistent pressure from the blood flow on the weakened wall tissue can lead to eventual rupture of the vessel and consequential haemorrhaging. Treatments for aneurysms have tended to focus on reducing the pressure on the weakened vessel wall, for instance by diverting blood flow or by isolating the weakened vessel wall, for instance by means of a stent graft. Another treatment method involves filling the aneurysm sac with a filler material which stops the flow of blood into the sac and as a result stops or substantially reduces the pressure on the weakened walls. The filler may be an embolization coil, which will cause static blood around the embedded coil to clot, which blocks the sac and creates a protective barrier to prevent vessel rupture. In other methods the aneurysm may be filled with a biocompatible material, such as a hydrogel or a polysaccharide fibre, which may be of a biodegradable nature. A biodegradable filler performs the same function as an embolization coil, that is to fill the aneurysm sac and provide pressure protection to the weakened vessel walls, with the additional advantage of allowing remodeling of the vessel wall over time. Moreover, biodegradation of the filler will ensure that no foreign matter remains in the patient&#39;s vessel after conclusion of the treatment. 
         [0004]    A useful technique involves the administration of a filamentary filler material, which can be delivered endoluminally through a small diameter catheter. The filamentary material is biocompatible and potentially also biodegradable. In many instances it is optimal to use filamentary material having a very small diameter, which enables the use of a narrow diameter delivery catheter, useful for delivery through and into small diameter vessels, for filling small aneurysm sacs, and so on. However, narrow diameter filaments can be difficult to handle, both into the delivery apparatus and from the delivery apparatus into the delivery catheter. Similar problems can also be encountered with biological or similar filamentary material, such as material made from small intestine submucosa (SIS), which can be difficult to handle especially in filamentary form. 
         [0005]    Examples of endoluminal filament and coil delivery systems can be found in U.S. Pat. No. 6,458,137, U.S. Pat. No. 5,476,472, U.S. Pat. No. 6,379,329, US-2003/0225391, US-2011/0077681 and US-2013/0296917. 
       DISCLOSURE OF THE INVENTION 
       [0006]    The present invention seeks to provide improved delivery of filamentary material into a patient and improved apparatus therefore. 
         [0007]    According to an aspect of the present invention, there is provided medical filament delivery apparatus including: a filament drive unit provided with a feed chamber, a first inlet to the feed chamber connectable to a fluid supply, a second inlet to the feed chamber connectable to a supply of filamentary material, and an outlet from the feed chamber attached or attachable to a delivery catheter; a tubular guide element disposed or disposable at least partially within the feed chamber and between the second inlet and the outlet; the guide element including a tubular structure with an internal lumen, the tubular guide element including a proximal end and a distal end, the proximal end having an inner first diameter; and an elongate filamentary material feed tube including a distal end having an outer second diameter, wherein the feed tube distal end is insertable into the proximal end of the tubular guide element, such that filamentary material from the feed tube is able to pass into the tubular guide element; the feed tube including a fixation member for fixing an end of filamentary material to or proximate the feed tube distal end, the fixation member providing for release of the fixed end of the filamentary material on insertion of the feed tube distal end into the proximal end of the tubular guide element. 
         [0008]    It can be problematic to feed the first end of filamentary material into the delivery apparatus and the structure disclosed herein provides a solution to experienced problems. The feed tube holds the end of the filamentary material, ensuring that it is appropriately positioned into the delivery apparatus, in this case in the tubular guide element, and also provides for release of the end of filamentary material when in the assembled condition, such that the filamentary material can be dispensed into the patient. The apparatus provides a mechanism which can ensure that the end of the filamentary material is not lost during assembly of the apparatus. 
         [0009]    The fixation member preferably provides for release of the filamentary material by severing of the fixed end of the material. The process of release of the distal end of the filamentary material can therefore be simple and reliable, preferably requiring no specific action on the part of the physician beyond putting the component parts of the assembly together. 
         [0010]    In a preferred embodiment the fixation member is a slot or hole at the feed tube distal end, wherein the end of the filamentary material is trappable in the slot or hole. Advantageously, the feed tube distal end is a close fit in the proximal end of the tubular guide element, such that filamentary material trapped in the slot or aperture is cut, or severed, when the feed tube distal end is inserted into the proximal end of the tubular guide element. This structure provides a simple, effective and automatic mechanism for releasing the distal end of the filamentary material as the feed tube is fitted into the guide tube. No other action is required by the user and there is no risk of the user prematurely releasing the filamentary material. Furthermore, the structure ensures correct positioning of the filamentary material into the delivery apparatus for reliable delivery into a patient. 
         [0011]    In the preferred embodiment, the tubular guide element includes at least one aperture therein, the at least one aperture allowing fluid in the feed chamber to flow into the internal lumen thereof. In a practical example, the tubular guide element is a cannula provided with a plurality of apertures therein. 
         [0012]    Advantageously, the apertures in the tubular guide element extend generally in a longitudinal direction of the tubular guide element. The apertures provide for supply of delivery fluid directly into the guide element and to the filamentary material held therein. 
         [0013]    There is preferably provided a dispenser of filamentary material, the feed tube being coupled to the dispenser. The feed tube may be attached to a casing of the dispenser and supported thereby. 
         [0014]    Advantageously, the feed tube and the second inlet of the drive unit include cooperating fixation members for fixing the feed tube to the drive unit. 
         [0015]    There is preferably provided a sealing element at the outlet and/or inlet of the filament drive unit, whereby fluid exits the feed chamber via the lumen of the tubular guide element. 
         [0016]    In an embodiment, the proximal end of the tubular guide element extends beyond the second inlet of the filament drive unit. Similarly, the distal end of the tubular guide element may extend beyond the outlet of the filament drive unit. Preferably, a delivery catheter is coupled to the outlet of the filament drive unit, wherein the proximal end of the tubular guide element extends into the delivery catheter. 
         [0017]    Preferably, the tubular guide element is fitted to a coupling member, the coupling member being attachable to the filament drive unit. The coupling member may be attachable at the outlet of the filament drive unit. In some embodiments at least, the coupling member may be disposed at an intermediate position along a length of the tubular guide element. 
         [0018]    There is also described a method of delivering filamentary material into a vessel or other organ of a patient by means of delivery apparatus including: 
         [0019]    a filament drive unit provided with a feed chamber, a first inlet to the feed chamber connectable to a fluid supply, a second inlet to the feed chamber connectable to a supply of filamentary material, and an outlet from the feed chamber attached or attachable to a delivery catheter; 
         [0020]    a tubular guide element disposed or disposable at least partially within the feed chamber and between the second inlet and the outlet; the guide element including a tubular structure with an internal lumen, the tubular guide element including a proximal end and a distal end, the proximal end having an inner first diameter; and 
         [0021]    an elongate filamentary material feed tube including a distal end having an outer second diameter, the feed tube including a fixation member which fixes an end of filamentary material to or proximate the feed tube distal end; 
         [0022]    the method including the steps of: 
         [0023]    inserting the feed tube distal end into the proximal end of the tubular guide element, such that filamentary material from the feed tube is able to pass into the tubular guide element, wherein said insertion causes release of the fixed end of the filamentary material; and 
         [0024]    supplying driving fluid into the feed chamber, said driving fluid driving said filamentary material into and through the delivery catheter. 
         [0025]    Advantageously, insertion of the feed tube distal end into the proximal end of the tubular guide element severs the fixed end of the material. 
         [0026]    The method may include the step of supplying fluid to the supply of filamentary material. This fluid can be used to wet the filamentary material and/or as a second source of driving fluid. 
         [0027]    Other features, aspects and advantages of the apparatus disclosed herein will become apparent from the specific description which follows. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0028]    Embodiments of the present invention are described below, by way of example only, with reference to the accompanying drawings, in which: 
           [0029]      FIG. 1  shows various views of a distal end of the feed tube of the preferred embodiment of apparatus; 
           [0030]      FIG. 2  shows a preferred embodiment of the tubular guide element of the delivery apparatus; 
           [0031]      FIG. 3  shows how the tubular guide element can be fitted to a standard Y-fitting; 
           [0032]      FIG. 4  is a perspective view of the major part of the delivery apparatus of the preferred embodiment; 
           [0033]      FIG. 5  is a partial cross-sectional view showing the flow of driving fluid through the components of the delivery apparatus; 
           [0034]      FIG. 6  is a perspective view in partial cross-section of an example dispenser of filamentary material for attachment to the delivery apparatus; 
           [0035]      FIG. 7  is a side elevational view in partial cross-section showing the connection between the delivery tube and the tubular guide element of the preferred embodiment of apparatus; 
           [0036]      FIG. 8  is a perspective view of the apparatus in its assembled form; and 
           [0037]      FIGS. 9 and 10  show how an aneurysm sac can be filled with filamentary material. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0038]    Preferred embodiments of the apparatus taught herein are described below and shown in the accompanying drawings. The skilled person will appreciate that the drawings are not to scale and also that minor elements and features of the apparatus familiar in the art but not relevant to the teachings herein are not shown or described for the sake of conciseness and clarity. 
         [0039]    The embodiments described herein are shown arranged for delivering long lengths of filamentary material into a patient. The nature of the material is not relevant to the disclosures herein but it may preferably be of SIS (small intestine submucosa), polysaccharide, a biocompatible polymeric thread or other biocompatible material. The apparatus is suitable for delivering material of small diameter through a small diameter delivery catheter. It can also be used for large diameter material and catheters. 
         [0040]    Referring first to  FIG. 1 , this shows various views of the feed tube assembly  10  of the preferred embodiment of apparatus taught herein. The assembly  10  includes an elongate feed tube member  12  for holding and feeding filamentary material into the delivery apparatus, as described below in detail. A luer fitting  18  is attached at the distal end of the feed tube member  12  and includes a luer lock  20  of conventional form. A lumen extends through the luer fitting  10  and the feed tube member  12 . 
         [0041]    At the distal end  16  of the feed tube member  12  there is located a slit  22  having a diameter preferably just smaller than the diameter of filamentary material intended to be held in and fed through the feed tube assembly  10 . The slit  22  has a length at least as great as the diameter of the filamentary material, though it is to be understood that the length of the slit  22  is not critical. 
         [0042]    The feed tube  12  is preferably rigid and may be made of a metal, metal alloy, rigid plastics, ceramic or other suitable material. The luer lock assembly  18  may typically be made of a plastics material or of metal or metal alloy. 
         [0043]    With reference to the lowermost drawing in  FIG. 1 , a filament storage device  30  is shown, in which a length of filamentary material  40  (seen better in  FIG. 6 ) is, in this example, held on a cylindrical drum, which preferably has a helical groove running across its outer surface, such that individual turns of the filamentary material  40  are held separated from one another by the turns of the helical groove. The filament storage device  30  includes a male luer fitting  42  at an outlet of the device  30  and a female luer fitting  44  at an inlet of the device. The luer fitting  44  can be used to supply further filamentary material  40  into the storage device in cases where this is needed and/or to supply wetting fluid (for example saline solution). As will be apparent, the luer fitting  18  can be locked into the outlet luer fitting  42  of the filament storage device  30  and such that the lumen therein aligns with the lumen within the outlet fitting  42 , such that filamentary material  40  can pass from the storage device  30  into the feed tube assembly  10 . Typically, the feed tube assembly  10  is attached to the filament storage device  30  during assembly and such that the distal end  46  of the filamentary material  40  can be trapped into the slot  22  and pulled back on itself so that the distal end  46  of the filamentary material points in a proximal direction (in practice, as will be apparent below, in a direction away from the direction of insertion of the feed tube assembly  10  into the delivery assembly). 
         [0044]    The feed tube  12  and the lumen therein (and similarly the other lumens of the apparatus) are preferably circular in transverse cross-section in order to accommodate the filamentary material, which in the preferred embodiments is made of a relatively soft fibrous material. 
         [0045]    Referring now to  FIG. 2 , this shows a perspective view of the tubular guide element  50  of the delivery apparatus. The guide element  50  includes a double luer fitting  52  having at one end a catheter luer lock  54  and at the other end a Y-fitting luer lock  56 . Integral with the double luer fitting  52  is a tubular guide member  60  which extends through the double luer fitting  52  and includes a distal end  62  and a proximal end  64 . The tubular guide member  60  may be made of a metal or hard plastics material, or other suitable material. It may be made of the same material as the elongate feed tube  12 . 
         [0046]    The tubular guide member includes a plurality of flushing holes  66  proximal of the Y-fitting lock  56  and spaced from one another in the longitudinal direction of the tubular guide member  60 . In  FIG. 2  there are shown two flushing holes  66  in the tubular guide member  60  but the number of flushing holes may vary. 
         [0047]    Referring to  FIG. 3 , the tubular guide assembly  50  is designed to fit within a standard Y-fitting  70  and such that the guide tube  60  passes through the main body of the Y-fitting  70 , the tube  60  being long enough to extend beyond the proximal end  72  of the Y-fitting  70 , as will be apparent from  FIG. 4 . For this purpose, the guide tube  60  has an outer diameter which is preferably a close fit to seal in the Y-fitting  70 . 
         [0048]    Referring to  FIG. 4 , this shows the major components of the fluid delivery section of the filament delivery apparatus  80 . In  FIG. 4 , the tubular guide assembly  50  has been inserted into the Y-fitting  70 , with its Y-fitting connector  56  locked into the luer connector  74  of the Y-fitting  70 . The guide tube  60  extends, as explained above, through the main body of the Y-fitting  70  and beyond the proximal end  72  of the Y-fitting  70 , such that the proximal end  64  of the guide member  60  is exposed. The distal end  62  of the tubular member  60  extends in a distal direction and in practice so as to fit within a lumen  92  of a catheter assembly  90 . The catheter assembly  90  includes a catheter element  94 , typically of sufficient length to be able to be fed endoluminally through a patient&#39;s vasculature from a remote percutaneous entry point and up to the site within the patient at which the filamentary material is to be delivered. In some embodiments the catheter assembly  90  may be integral with the Y-fitting  70 . In some embodiments the catheter  94  may be of a small diameter, that is a micro-catheter. 
         [0049]    The side arm  76  is in use attached, in this example, to a feed catheter assembly  100  which can be connected to a supply of driving fluid, for instance saline solution. 
         [0050]    With reference now to  FIG. 5 , this shows two cross-sectional views of the assembly of  FIG. 4 . Driving fluid from the feed catheter  100  into the side arm  76  of the wire fitting  70  is depicted by the black dots in  FIG. 5 . The Y-fitting  70  provides what could be described as a feed chamber  78  of the apparatus. The Y-fitting  70  includes a disk valve  82  at its proximal end  72 , through which the proximal end  64  of the guide tube  60  can pass. The valve  82  delimits one end of the feed chamber  78 . A valve similar to the valve  82 , located at the distal end  74  of the Y-fitting  70  (but not visible in  FIG. 5 ), is located at the distal end of the feed chamber  78 . In this manner, fluid passing into the feed chamber  78  from the side arm  76  is trapped within the feed chamber  78 , apart from being able to pass into the tubular guide member  60  via the apertures  66 . As can be seen in the enlarged section of  FIG. 5 , the apertures  66  are preferably located at the junction with the side arm  76 . In this manner, drive fluid under pressure fed into the side arm  76  will pass into the lumen of the tubular guide member  60  and therefrom through the catheter  94 . As the skilled person will understand, fluid in the catheter  94  will pull filamentary material through the catheter  94 , until it is dispensed from the distal end of the catheter  94 . 
         [0051]    With reference now to  FIG. 6 , this shows how the feed tube assembly  10  and the filament storage device  30  are connected to the other components of the delivery apparatus. With reference first to the enlarged section of  FIG. 6 , the distal end  46  of the filamentary material  40 , held within the slot  22 , may be fixed to the outside surface of the feed tube  12 , for instance by a spot of adhesive  102 . 
         [0052]    The distal end  16  of the feed tube  12  can be slid into the proximal end  64  of the tubular guide member  60 . The arrangement is such that the feed tube  12  and the tubular guide member  60  are a close fit one within the other. Specifically the outer diameter of the feed tube  12  is designed to be about the same or only slightly smaller than the inner diameter of the guide tube  60 , such that when the feed tube  12  is inserted into the guide tube  60  the distal end  46  of the filamentary material  40  is severed, in practice releasing the filamentary material  40  from its attachment to the feed tube  12 , enabling it to move out of the feed tube  12  for delivery in to a patient. 
         [0053]      FIG. 7  shows a partial cross-sectional view of the apparatus. In the enlarged section of  FIG. 7 , the distal end  46  of the filament is shown in outline to depict how this would be severed on insertion of the distal end of the feed tube  12  into the guide tube  60 . Once so severed, the remainder of the distal end  46 ′ of the filamentary material is then free to move within the lumen within the tubes  12 ,  60  and thus to be driven through the delivery assembly and the catheter  94  by the driving fluid (in practice being pulled along with the flow of the driving fluid). 
         [0054]    As the distal end  46  of the filamentary material  40  is fixed to the feed tube  12  there is no risk of mis-feeding of the filamentary material into the delivery device and, moreover, there is no mechanism required to insert the distal end of the filamentary material into the catheter  94  apart from by inserting the rigid feed tube  12  into the tubular guide  60 , a much simpler operation given the nature of that component. 
         [0055]      FIG. 8  shows the apparatus in its fully assembled form. The filament storage device  30  is shown fitted to the feed tube assembly  10 , which itself is fixed into the drive assembly  80 , the latter being attached to the micro catheter assembly  90 . As can be seen in  FIG. 8 , in this example they are provided two syringes  110 ,  120 , for providing, respectively, driving fluid and wetting fluid. The syringe  120  provides wetting fluid for wetting the filamentary material and keeping this in a suspended state within the storage device  30 , which facilitates the delivery of the filamentary material out of the storage device. The syringe  110  provides the driving fluid for feeding through the catheter assembly  90  and pulling the filamentary material with it. 
         [0056]    A flushing valve  130  may be provided at the outlet of the syringe  110 , and is closable to prevent inadvertent operation of the assembly until deployed as desired. 
         [0057]    In this embodiment, a syringe  110  is used as the supply of driving fluid and it is considered this would be optimal in most circumstances. In other embodiments, a different source of driving fluid other than a syringe may be used, such as a fluid pump and so on. 
         [0058]    Referring now to  FIGS. 9 and 10 , these show two views of a vessel  130  having an aneurysm  134  therein. The aneurysm  134  forms a sack to one side of the vessel  130 . A support structure, typically a stent,  140  is shown positioned across the neck  136  of the aneurysm  134  and is used to hold filamentary material within the aneurysm sack  34 .