GB2143134A - Blood access device - Google Patents

Abstract

A needle assembly for a blood access device comprises a body member 41 having a pair of hollow needles 42, 43 and a pair of tubing connectors extending therefrom, each of the needles being connected to one of the tubing connectors by a channel in the body member, each channel diverging so that the needles are closer together than the connectors. <IMAGE>

Description

1 GB 2 143 134 A 1

SPECIFICATION Blood Access Device

Background of the Invention

The present invention is directed to an implantable device providing access to the blood circulatory system. While applications for the device can be for a variety of purposes, it is anticipated that principal uses will be in the field of hemodialysis of chronic uremic patients, as access for blood sampling and for treatment of diseases such as diabetes and for forms of chemotherapy and hyperalimentation.

Various approaches to implanted blood access devices are known; however, none of these have been entirely satisfactory. Shunt techniques have problems of infection, clotting and erosion. The arteriovenous fistula has some advantages over shunts, but there is a need for recurring needle puncture and there still are infection problems as well as other disadvantages.

It is also known to provide implanted blood access devices wherein access to the circulatory system is accomplished by means of a percutaneous spigot valve.

Brief Description of the Invention

In accordance with the present invention, an implantable generally tubular T-shaped structure is provided in which the stem of the T is constructed and arranged to cooperate with a novel needle structure that penetrates the seal means at the junction of the stem of the T with the balance of the T structure. By reason of the structure of the invention, the interior stem portion of the T can be rinsed clean and sterilized between each use without elaborate procedures' thus minimizing the likelihood of infection as a result of access to the circulatory system. The invention thus provides an implantable blood access device which may be semi-permanently installed into the circulatory system and used repeatedly. This invention also has a low profile body external portion which minimizes the possible catching of clothing and the like on the external portion.

Cooperating structures include a preferred septum having a groove in the side thereof encircling the septum and an elastomeric ring carried within the side groove, needle assemblies which provide access to the circulatory system through the septum and flexible caps for sealing the stem of the implantable device from the outside atmosphere which may be fitted in place or removed without the necessity of specialized tools.

Cooperating accessories include a septum assembly insertion tool which simultaneously inserts the septum, a pressure plate and a retaining ring into the stem cavity of the implantable device. Another accessory is specialized forceps clamp for gripping the flanged upper edge of the stem of the implantable device. The clamp has curved finger holds which permit the stem of the implanted device to be stabilized during insertion of the septum assembly.

Yet another accessory is a back-up septum system for plugging the cavity in the stem of the implanted device above the principal septum when the principal septum begins to fail. The back-up septum system comprises a specially designed spacer member, a septum conforming generally to the shape of the stem cavity above the retaining ring for the principal septum and clamp or retaining ring means for holding and compressing the backup septum within the stem cavity. The back-up system permits continued access to the circulatory system until assistance can be obtained in replacing the primary septum.

A final accessory is a hemispherical implant cap which protects the stem cavity of the implantable device during implantation of the device in the body.

Brief Description of Drawings

Fig. 1 is an exploded pictorial view of a device in accordance with the invention including the implantable portion, a two needle cooperating member and a modified forceps for use in assembly and disassembly of the implanted septum assembly; Fig. 2 is a plan top view of the implantable Tshaped assembly; Fig. 3 is a side elevational view partly in section as taken along the lines 3-3 of Fig. 2; Fig. 4 is a plan view of the septum; Fig. 5 is a section view along lines 5-5 of Fig.

4; Fig. 6 is a plan view of the bottom or interior facing side of the septum; Fig. 7 is a sectiona(view of a device in accordance with the invention with the cooperating needle assembly in operative engagement with the implantable portion; Fig. 8 is a side elevational view partly in section of the T-shaped implantable structure and cover assembly; Figs. 9 and 10 illustrate a needle and sheath assembly showing respectively the sheath covering the opening in the needle end and withdrawn to expose the opening; Fig. 11 is a top plan view of an assembly including a pressure plate with an aligning peg; Fig. 12 is a side cut away view of the assembly of Fig. 11 where the coating with pyrolytic carbon is not included; Fig. 13 is a side elevational view, partially cut away of a modified sealing cap; Fig. 14 is an exploded pictorial view of a T shaped device similar to that of Fig. 1 and including the preferred septum cap member and needle carrier of the present invention; Fig. 15 is a pictorial view of an obturator for use with the septurns of the present invention; Fig. 16 is a plan top view of the implantable T shaped assembly with the preferred septum included therein; Fig. 17 is a side elevational view partly in 2 GB 2 143 134 A 2 section as taken along the lines 17-17 of Fig. 16 with an implant cap shown in phantom; Fig. 18 is a plan view of the top side of the preferred septum; Fig. 19 is a section view along the lines 19 19 of Fig. 18; Fig. 20 is a plan view of the bottom interior facing side of the preferred septum; Fig. 21 is a sectional view of the implantable blood access device with the preferred needle assembly in operative engagement with the preferred septum; Fig. 22 is a side elevational view partly in section of the implanted blood access device and an alternate cap structure; Fig. 23 is a side elevational view partly in 80 section of the preferred needle assembly of the present disclosure;

Fig. 24 is a pictorial view of septum loading tool of the present invention; Fig. 25 is a sectional view of the septum loading too[ taken along the line 25-25 of Fig. 24; Figs. 26A, 26B, 26C and 26D are sectional views of the loading tool taken along the lines 26A-26A, 2613-2613, 26C-26C and 26D26D, respectively, of Fig. 25; Fig. 27 is a view of the septum loader as in Fig. 25, but with the loader inserted into the stem of the blood access device and the plunger depressed; Fig. 28 is a top plan view of the forceps clamp of the present invention; Fig. 29 is a sectional view of the ends of the forceps clamp with portions removed showing the clamp in engagement with the upper flange of the 100 blood access device stem; Fig. 30 is a side plan view of the end of the forceps clamp; 40 Fig. 31 is a view of the forceps clamp taken along line 31-31 of Fig. 30; Fig. 32 is a pictorial view of the forceps clamp as it is held in use; Fig. 33 is an exploded pictorial view of the back-up septum system of the present invention with the implantable blood access device shown 110 in phantom; Fig. 34 is a side plan view partly in section of the back-up septum, spacer and clamp in operative engagement with the T-shaped blood access device of the present invention; Fig. 35 is a top plan view of the spacer member 115 for the back-up septum system; Fig. 36 is a sectional elevation view of the spacer member taken along lines 36-36 of Fig. 35:

Fig. 37 is a top plan view of the implantable T- 120 shaped assembly as in Fig. 16, but with an alternate back-up septum held in place above the principal septum by means of a retaining ring; Fig. 38 is a side elevational view partly in section as taken along lines 38-38 of Fig. 37; and Fig. 39 is a pictorial view of the blood access device of the present invention showing the implant cap thereon and suture winding thereabout for implantation in the body.

Detailed Description of the Invention Referring to the drawings, there will be seen in

Fig. 1 a device in accordance with the invention which includes a Tshaped unitary tubular body generally designated 10 having a stem portion 11 and a straight tube portion 12. Body 10 is formed of a unitary body of a biologically compatible material such as titanium. It is highly advantageous that body 10 be of a unitary construction to eliminate extraneous cavities at points of assembly of non-unitary bodies. At least the external surfaces of body 10 may be coated with a continuous layer of pyrolytic carbon to enhance biocompatibility. This is particularly of importance for surfaces that will be blood contacting surfaces such as the bore when blood is a flow therethrough. Pyrolytic carbon coatings are known to be biologically compatible materials and have been used in implanted structures. See, for example, U.S. Patent Number 3,783,868. Alternatively, the body 10 may be uncoated titanium or other rigid material. As illustrated in Fig. 7, a snugly fitting sleeve member 34 of graphite lines the interior of tube 12 and underlies coating 13. For coating the interior of a tube, it has been found desirable to have the graphite sleeve to serve as a substrate for the pyrolytic carbon.

Expanded polytetrafluorethylene tubes 14 are shown joined to ends of 12 by slipping over these ends. Dacron (polyethylen eterep hth a fates) or other body compatible polymeric materials may be used rather than polytetrafluorethylene (Teflon). The expanded polytetrafluorethylene slipped over the ends of 12 may be provided as an intermediary for joining blood vessels to the assembly 10. A Teflon shrink band 67 aids in holding the sleeve on. A suitable expanded polytetrafluorethylene is sold under the trade name Gore-Tex by W. L. Gore Company of Newark, Delaware. It should be understood that tubes 14 are elective in that it is not necessary that they be present.

Alternatively, an uncoated device 10 as shown in Fig. 12 may be directly placed in a blood vessel. In such a case, the blood vessel would be slit longitudinally for a sufficient distance for the device 10 to be inserted and the vessel drawn around the device and sutured into place. A collar member 29, as described below, would be used around a portion of the stem to aid in tissue ingrowth to the stem portion.

As can best be seen in Figs. 3 and 7, body 10 is formed with an internal extension 15 which substantially provides a separation of the internal chamber of T-shaped member 11 from the cavity of portion 12 except for the openings 16 and 17.

Member 15 provides a support surface for a septum member 18. Member 18 is formed of an elastomer such as natural rubber and, as can be seen in Figs. 2, 4, 5 and 6, has a broadly elliptical 3 GB 2 143 134 A 3 configuration. The purpose of this shape is best understood with reference to Fig. 2.

In Fig. 2, there is seen a top view of stem 11. As can be seen, stem 11 has a generally round opening. There is provided an internal shape in the opening along the axis of tube 12 which conforms generally to the ends 19 of the septum 18 for indexing purposes.

As can be seen in Figs. 2, 4, 5 and 6, septum 18 is pre-cut in a three-directional star or tricuspid form 20. Preferably, although not mandatorily, the hole 21 may be completely through septum 18. These cuts facilitate passage of a needle through the septum. At the outer surface of the septum 18, there is a countersunk region 36 for receiving a needle. The cuts 20 are positioned so that when member 18 is indexed into the opening of T-stem 11, cuts 20 are centered on openings 16 and 17. As a preferred alternative, the needle opening in septum 18 may be actually formed into the septum at the time the septum is fabricated. When the septum is pressed into place, the compression will seal the openings 21 (see Figs. 11 and 12 also).

Overlying septum 18 is a pressure plate 22 of titanium or the like which defines openings 23 which are spaced to conform in position to slits and openings 16 and 17. Pressure plate 22 is, in turn, locked into engagement with septum 18 by a spring retaining ring 24.

A cap member 26 snaps over a flanged edge 27 as seen in Fig. 8 and is held in sealed relationship therewith by a retaining ring 28. The lower flared edge 70 of cap 26 will be spaced, in use, slightly above the skin 25 of the user.

Pressure contact with the skin by edge 70 is undesirable as necrosis may occur. Overall, there is provided a profile for the exposed external portion of member 10 that is less likely to catch an object such as clothing. Cap 26 also provides a 105 means whereby an antiseptic such as Betadine (iodine polyvinylpyroliclone complex) may be included in cavity 30 to maintain the unit sterile between usage.

The assembly described above is implantable in the patient by surgical techniques that are known and form no part of the invention. It is desirable to have the amount of the stem protruding above the skin line at a minimum amount compatible with permitting a cap member seal. Implantation may be in various manners and modes including, but not limited to, the following: by anastomosis to 14, i.e. by splicing the ends of a blood vessel to opposite ends of assembly 10. Assembly 10 maybe positioned into a blood vessel that has been longitudinally slit for a distance sufficient to permit insertion of the device. In this latter case, the blood vessel is sutured about the device to form a seal, and the sleeves 14 are not used.

To aid in accomplishing tissue growth onto the portion of the stem 11 below the skin line 25, a collar member 29 of porous plastic material such as polyethyleneterephtha late, sold by E. 1. Dupont under the trademark Dacron maybe used. The portion of stem 11 above the dermis region is uncoated to reduce the risk of infection occurring by bacteria making their way down along the collar 29. If the external surface of stem 11 is titanium, the titanium may have a matte surface in the region of collar 29 and thus, eliminate need of collar 29.

When access is to be made to the blood system, the cap 26 is removed. The interior cavity region 30 thus exposed can be rinsed with appropriate sterilizing agents that are removed prior to insertion of a needle through openings 23, 20 and 16. It is preferred that cavity 30 be filled with and holds a sterilizing solution, such as described previously, between usage. This sterilizing solution can be placed in cavity 30 before closing with cap 26, or a hypodermic may be used to inject the solution through the cap. Desirably, the needle used to penetrate the septum will have a closed rounded end with an opening at the side thereof. A blood sample can be drawn or material such as drugs inserted through the needles as desired.

The device described can be implanted into a go patient and remain essentially permanently. However, if a need arises to replace the septum 18 after prolonged use, this can readily be done without need of surgical procedures. A modified forceps 31 is machined or ground to provide tips 32 of a size to be positioned into holes or recesses 33 in retaining ring 24. The ring may be withdrawn along with pressure plate 22 and septum 18 for cleaning and/or replacement. Of course, steps should be taken to block the body blood pressure so as to prevent appreciable blood flow outwardly through openings 16 and 17 during the assembly or disassembly.

To insure a tight seal of septum 18, with the interior wall of stem 11, it may be desirable to shape the side walls 35 of the septum in a concave manner as shown. A second purpose in such shaping is to provide for the displaced material of septum 18 resulting from introduction of needles through the septum.

While the implanted assembly 10 can be used with conventional hydodermic assemblies, it is desirable to utilize a cooperating assembly such as a member 40. Even when a simple needle is on a standard syringe, it is desirable that the needle have a rounded end as will be described below. Member 40 is constructed of a cylindrical block of metal 41 through which two hollow needle members 42 and 43 extend in sealed relationship to member 41. These needle members are positioned so as to index with openings 23 in pressure plate 22. As can best be seen in Fig. 7, the needles have rounded closed ends 44 and have a side opening 45 and 46, respectively. As shown, the needle is solid (cavityless) below the lower edge of openings 45 and 46. This construction is highly advantageous. The rounded closed end readily passes through septum 18 with a reduced tendency to cut and break pieces of a septum as a result of passage therethrough over use of a conventional hypodermic needle.

4 GB 2 143 134 A 4 The solid lower end avoids the presence of entrapped air. One can also position the openings in the needles so that, if blood flow is in the direction shown by arrow 47, the needle opening is directional to withdrawal of blood while opening 46 is directional to return of blood. The top of the needle can be jointed to any suitable construction to be connectable to external blood flow tubing or other types of apparatus.

Referring now to Figs. 9 and 10, there is 75 illustrated a form of needle assembly generally designated 50 for use with the implanted portion 10. In this form, there is provided a block of plastic or metal 51 which is of a size to fit down into the cavity of stem 11 in a manner similar to that shown in Fig. 7. However, in this instance, member 51 includes an off-center opening therethrough 52 for use as will be described below. Needle members 53 and 54 pass through member 51 and in conjunction with some type of 85 tubing, syringe or the like (not shown). The needle members are of a substantially identical configuration to that described with respect to Fig. 7. A sheath assembly 55 is provided having two rigid sleeve members 56 and 57, respectively, that are of a hollow configuration, such as a slip over needles 53 and 54, respectively. Members 56 and 57 are welded or otherwise secured to plate 55. In an uncompressed condition, the assembly 55 is held in position as seen in Fig. 9 by a spring member 58. In this position, the openings 59 and 60, as best seen in Fig. 10, are covered by sleeves 56 and 57. As can be seen in Figs. 9 and 10, the sleeve members have a rounded shoulder 61 at the lower edge thereof which facilitates the penetration of the openings through septum 18. The length of sleeves 56 and 57 are sufficient to insure that the openings 59 and 60 do not act as a cutting edge to slice material of the septum off as the needles are penetrated through the 106 septum. Once the sleeves have penetrated through the septum by assertion of the assembly into the top of stem 11, resistance of the pressure plate 22 and retaining ring 24 force spring 58 into a flat shape as illustrated in Fig. 10, and the sleeves 56 and 57 no longer cover openings 59 and 60.

With reference to Figs. 11 and 12, it will be seen that the implanted portion of the device is substantially identical to what has been described 115 previously with respect to Figs. 1 through 7, except for the absence of pyrolytic coating and other differences to be described. The differences lie in the usage of a pressure plate 62 which has projecting upwardly therefrom an off-center locater pin 63 which is positioned so as to cooperate with opening 52 of the needle assembly as illustrated in Figs. 9 and 10. This locater pin provides two functions. First, when one is utilizing the needle assembly, it insures proper alignment of the needle members with the openings through the pressure plate and septum. Second, when the implanted device is not being used to gain access to the blood vessels, the pin 63 is utilized as a further attaching means to secure a cap 64 (see Fig. 13) to the exposed portion of stem 11. As can be best seen in Fig. 13, the cap member is adapted to slip over the edges of the stem portion member 10 to provide a sealing engagement therewith. In this instance, rather than having a retaining ring 28 completely surround the cap and stem portion, a built-in retaining ring 65 aids in gripping the locater stem 63 insuring that the cap is held in tight relationship with stem 11. As in the instance of the description with regard to Fig. 8, the cavity between the pressure plate 22 and the top of the stem 11 is again normally kept full of a sterilizing solution so as to insure that the device is ready for the next actual access use to the bloodstream.

It will be noted in Figs. 11 and 12 that the septum member 18 is shown as having a precast opening 21 therethrough described above. As the septum has been squeezed into place in the stem, the hole has been closed by the natural resiliency of septum 18, although it readily opens to accept needles.

Preferred Embodiments Referring again to the drawings, there will be seen in Fig. 14 a blood access device similar to that shown in Fig. 1, which includes a T-shaped unitary tubular body generally designated 10 having a stem portion 11 and a straight tube portion 12. Body 10 is formed of a unitary body of a biologically compatible material such as titanium. At least the external surfaces of body 10 may be coated with a continuous layer of pyrolytic carbon to enhance biocompatibility.

Expanded tetrafluoroethylene tubes 14 are shown joined to the ends of tube portion 12.

As can best be seen in Figs. 17 and 21, body 10 is formed with an external extension 115 which substantially provides a separation of the internal chamber of T-shaped member 11 from the cavity of portion 12 except for the opening 116. Member 115 provides a support surface for an improved elastomeric septum member 118 through which a needle or needle pair may gain access to the bloodstream. Member 118 has a broadly elliptical configuration. As can be seen in Fig. 16, stem 11 has a generally round opening. However, there are provided along the axis of tube 12 oppositely disposed protrusions 119 so that the stem opening has an internal shape which conforms generally to the ends 120 of septum 118 for indexing purposes.

As previously described, a pressure plate 22 of titanium or other substantially biologically compatible material which defines openings 23 overlies the septum. Openings 23 conform in position to slits 121 in the septum and opening 116 in the T-stem. Pressure plate 22 is, in turn, locked into engagement with septum 118 by a spring retaining ring 24.

Preferred Septum It is desirable that septum 118 have a configuration that will allow a maximum number GB 2 143 134 A 5 of needle penetrations without leakage through the needle passage. Whereas the septum configuration previously described, which included a precut three-directional star-shaped needle opening and concave septum edges, provides reasonable performance with a natural rubber septum, silicone based elastomeric septurns having such a configuration typically being leaking after 10 or less penetrations.

Silicone elastomers, however, have been found to 75 be preferred over natural rubber for septurns of the present invention because natural rubber deteriorates upon exposure to Betadine (iodine polyvinylpyroliclone complex) antiseptic which is used to sterilize the cavity above the septum.

The improved septum configuration of the present invention provides a substantial improvement in septum life (as measured by average number of penetrations before leakage), especially when silicone based elastomers; are used.

The principal problem in maintenance of septum life is caused by loss of material through coring, tearing or abrasion on the sides of the septum opening. Needles with rounded ends and holes in the side thereof substantially minimize coring problems. However, there remains some possibility of paring the septum material as the needle is inserted or removed along the side of the needle passage. The present design substantially lessens this problem by providing additional room for material displacement when the needle is inserted through the septum. By providing room for septum material displacement, the septum does not undergo as much compression when the needle is inserted, and consequently there is less tendency for septum material to push into the needle opening as the needle passes through the septum. 40 The preferred embodiment of the septum configuration is shown in Figs. 18 through 20. The precut needle openings are two slits 121 cut through the septum and extending from near the center of the septum out to the edge thereof. For 45 a septum of about.44 inches between ends 119, 110 the uncut center portion 130 is only about.04 inches wide. The edges of the septum have a groove 132 therein encircling the entire body thereof. Groove 50 132 carries an elastomeric ring 134 which preferably has an elliptical or circular crosssection. Ring 134, which has a smaller inner circumference than that of the septum, serves to hold the slit septum together and maintain the slit surfaces together in sealed relationship by 120 applying an inwardly directed radial force on the septum. The elliptical or circular shape of the ring leaves gaps in the groove into which septum material may move as the needle is inserted.

The septum is also preferably provided with an 125 elongated bottom recess 136 and a pair of generally semi-spherical top recesses 138 aligned with holes 23 in pressure plate 22 when assembled in the blood access device stem.

Functionally, the septum configuration shown 130 in Figs. 18 through 20 operates in two modes. When the needles are not inserted into the septum, the septum operates under a compression mode hermetically sealing the blood conduit by coacting with support member 115 and pressure plate 22. Elastomeric ring 134 provides radial compression to hermetically close the septum openings created by slits 12 1. When a needle or needles are inserted through the septum slits, the outwardly expanding septum material is accommodated by the space provided in groove 132 while the downwardly expanding septum material is accommodated by recess 136. The radial force exerted by the elastomeric ring 134 seals the needle or needles between the bloodstream and the cavity of stem 11. The radial force exerted by ring 134 thus causes the septum to operate in a shear mode. Because the present septum operates in both a compression and a shear mode, substantial increases in the working life of an elastomeric material, such as the preferred silicone based elastomers, are achieved.

The material displacement characteristics of the new septum are illustrated in Fig. 21.

Comparison of this Figure, in which the needles have been inserted through the septum with the relaxed septum shown in Fig. 17, shows that the gaps in groove 132 have been substantially filled and the bottom recess partially filled by displaced septum material. It should also be noted that, as the needles are inserted, septum material parts along the slit so that, when the needles have side openings aligned with the slit as shown in Fig. 21, there is a reduced tendency for septum material to press inwardly on the needle openings and become pared thereby.

Whereas the preferred embodiment of the septum of the present invention has a pair of oppositely directed slits through the septum extending all the way to the edges thereof, other slit configurations may be employed without departing from the essence of this invention embodiment if such configurations employ a circumferential side groove carrying an elastomeric compression ring therein. Specifically, it is contemplated that alternative embodiments may employ oppositely directed slits which do not extend all the way to the edges of the septum or a single central slit which likewise does not extend all the way to the edges of the septum.

It has also been found that, after insertion of the septum into the stem 11 of device 10, the slits 121 are initially resistant to penetration by a needle. It is therefore preferable that the initial penetration of the septum within the device be made by an obturator as shown in Fig. 15. The obturator has a body 230 which may be inserted into the cavity in stem 11, a pair of blank needles 232 which have rounded bottoms and no holes therethrough extending downwardly from body 230 and having the same spacing as that of a needle carrier structure disclosed hereafter, and afinger hold 234 to facilitate insertion of the device into the septum or removal therefrom. After one 6 GB 2 143 134 A 6 or two penetrations by the obturator, the septum is much less resistant to penetration by a needle and therefore needles having holes in the sides thereof may be inserted repeatedly with a reduced likelihood of paring or coring the slit surfaces.

Preferred Cap Structure The preferred cap member 140, shown in Figs. 14 and 22, snaps over flanged edge 142 of the blood access device stem. The cap member is held in sealed relationship therewith without the need for a retaining ring. This is accomplished by making the cap from a flexible material and by providing the interior side surface of the cap with a groove 144, the diameter of which is slightly smaller than that of the outer diameter of flanged edge 142 with which the cap surface engages. It is necessary that the cap be made of a flexible material so that it may be snapped over the slightly larger flange 142. The preferred cap also has a downwardly projecting central portion 147 which fits into the cavity of stem 11 for alignment purposes.

The outer projecting surface 146 is flared downwardly in a cone-shaped manner, the lower flared edge 149 being spaced when in use slightly go above the skin layer 150 of the user to avoid necrosis caused by pressure contact with the skin. To reduce pressure applied by the cap if it occasionally comes in contact with the skin, the flared exterior surface 146 of cap 140 is provided 95 with a plurality of slits 143 which increase the flexibility of the exterior surface 146. The slits 143 also provide increased air circulation under the cap, thereby aiding in preventing infectious growth on the skin around the protruding stem of member 10.

Preferred Needle Assembly The preferred needle assembly is illustrated in Figs. 15, 21 and 23. The needle carrier 152 includes parallel right angle tubing connectors 154 which provide the structure with an improved profile, allowing easy insertion of the needles into the device by thumb pressure and eliminating the awkwardness of tubing 155 coming in from different directions as is the case with the needle carrier structures described earlier. Maintaining the tubing pair in closely spaced parallel relationship and at right angles to the needle carrier lessens the dangers of entanglement and consequential damage to the implant or disconnection of the blood flow.

It is desirable, however, to have the needles more closely spaced together than is typically possible to space the tubing. The further the needles are spaced apart, the larger implanted member 10 must be. The preferred needle carrier 120 therefore contains internal channeling which allows for closer spacing of the needles than of the connected tubing.

Member 152 is most conveniently manufactured as a multi-part structure. The basic 125 element of the needle carrier is body member 158 which has lower apertures 160 into which needles 162 may be adhesively or otherwise secured. A circular flange 164 provides an attachment surface for a clip not shown to fasten the needle assembly to the flange 142 on stem 11. Male fittings 168 extend above flange 164.

Female openings on hollow right angle tubing connectors 154 engage members 168. The centers of needles 162 are spaced closer together than those of tubing connectors 154 and male members 168 by providing members 168 with a tapered non-concentric bore 170 as is best shown in Fig. 21. This bore channels the blood flow between the needles and the further spaced apart tubing connectors 154.

To assure proper orientation of the needles with the slits in septum 118, the tubing connector body 158 may be provided with protrusions not shown which conform to the internal shape of the opening in stem 11 as shown in Fig. 16.

The needles of the assembly preferably have two or more small side holes 178, one above the other, rather than a single large hole. The total cross-section of the holes should be greater than the needle internal diameter. This structure maintains flow while minimizing needle hole contact with the septum slit surfaces.

Unless the needles are made of a selflubricating material, the needles must be provided with a surface lubricant such as a silicone fluid or oil to reduce abrasion as the needles pass through the septum.

Other Cooperating Structures Septum Assembly Loading Too[ The septum loading tool is a device which permits rapid one-step insertion of a septum, pressure plate and retaining ring into the stem of the implantable device. This device lessens problems of patient blood loss during septum replacement because the respective parts do not have to be installed separately. The loading tool of the present invention is a simple device which holds all three sealing elements. These elements are rapidly and simultaneously inserted in the Tstem by insertion of the tool into the stem and depression of a plunger by the thumb. The simplicity of the device permits factory preassembly and packaging of a disposable loaded tool containing the retaining ring, pressure plate and septum in sterile condition.

The septum assembly loading too[ is shown in Figs. 24 through 28. The basic elements of the too[ are the hollow outer body member 180 and a plunger member 181 within and extending upwardly out of body member 180. Twin pins 182 attached to the lower surface of plunger member 181 extend downwardly through the lower opening in body member 180. For ease of manufacturing, body member 180 is made of two separate portions 183 and 184. Likewise, plunger member 181 is made of two parts, lower member 185 and upper member 186.

Member 184 has a stem insertion portion 187, 7 GB 2 143 134 A 7 the diameter of which, as can be best seen in Fig. 65 27, is slightly less than the blood access device stem opening above ring retaining ridge 188, but greater than that of the retaining ridge. Therefore, when the loading tool is inserted into the stem, the lower surface 189 of member 180 rests 70 against ring retaining ridge 188.

At least the lower portion 190 of the bottom opening into body member 180 has a diameter slightly less than that of retaining ridge 188.

When loaded, a crimped retaining ring 24 is held within body member 180 by inner opening surfaces 190. In the preferred embodiment, a shoulder 191 on the inner portion of member 180, against which the outer portion of the upper side of retaining ring 24 may rest, is provided.

The cross-section of the lower surface 192 of plunger member 181 is of sufficient width so that surface 192 engages at least a portion of the upper side surface of retaining ring 24 when the plunger is depressed. This engagement is shown in Fig. 27.

Pins 182 carry the pressure plate 22 and the septum 118, holding them in proper alignment for insertion. As shown in Fig. 27, when the plunger is depressed, the septum, pressure plate and retaining ring are pushed downward until the 90 retaining ring snaps into the retaining ring groove 196 under ridge 188. This requires some compression of the septum 118, as also shown in Fig. 27.

The plunger is held in the withdrawn position by means of rod 198 which passes through hole 199 in the plunger above the upper surface of body member 180. Rod 198 engages the upper surface of body member 180 and serves as a stop means for the plunger. Withdrawal of rod 198 100 permits the plunger to be depressed.

Stem Clamping Forceps Figs. 28 through 31 depict a stem clamping forceps 200 which is designed to be used with implanted blood access device 10. The body of the clamp is a standard forceps clamp having opposing arms 201 and 202. The ends of the clamp, however, are specially adapted to engage upper stem flange 142 of device 10. This is 110 accomplished by providing the ends of arms 201 and 202 with semi-circular interior opening surfaces 203 and 204, respectively, which are sized to fit about the outer diameter of stem 11.

Central grooves 205 and 206 securely engage flange 142 of stem 11 as shown in Fig. 29.

The ends of the clamp are also provided with oppositely disposed finger holds 208 which project upwardly and curve outwardly from the ends of the clamp. As shown in Fig. 32, these ear like finger holds are used to hold stem 11 against downward pressure which may be exerted on device 10, as for instance, when the thumb is used to depress the plunger of the septum loading tool as disclosed herein. The stem clamping 125 forceps may also be useful for holding the blood access device in place during surgical implantation thereof.

In the preferred form of the forceps clamp of this invention, arms 201 and 202 have a flattened S-shaped curve thereon as is shown in Figs. 30 and 32. This shape allows the clamp to be more easily manipulated since the ends of the clamp are held closely against the skin of the implant recipient.

Back-Up Septum System Although the septurns of the present invention have especially good sealing characteristics after repeated punctures, lifetimes do vary and it is conceivable that, on occasion, a septum may begin to leak before it has been replaced. A further cooperating structure for the implantable device of the present invention, therefore, is a clamp which may be used with a second or "back-up" septum placed in the cavity between the septum retaining ring and the top of the implanted T- stem. The clamp holds the back-up septum in place and deforms it in such a way as to assure that the septum seals around the interior surfaces of the T-stem, thereby sealing the device until the leaking primary septum can be replaced. The back-up septum may be provided with needle openings therethrough so as to allow continued access to the bloodstream.

The back-up septum clamp shown in Figs. 33 and 34 has three principal parts. Semi-circular members 210 and 211 having interior grooves 212 and 213, respectively, sized to engage flange 142 of stem 11, are held together by means of screws 214.

Within the cavity of stem 11, there is placed a spacer member 238, shown in detail in Figs. 35 and 36, which has an outer ring 240 and a depressed central portion 242. Spacer member 238 defines two holes 244 through which a needle pair may pass. Member 238 sits above retaining ring 24, with outer ring 240 providing an unbroken circumferential surface against which the lower edge of a back-up septum 218 may be compressed.

Circular elastomeric septum member 218 is placed within the opening in stem 11 above the spacer ring 238. The septum is held in place by clamp cap member 220. Cap member 220 has a central aperture 221 and a circular downwardly projection portion 222 which fits into the opening in stem 11. Cap member 220 is held in place by means of screws 223 which pass through holes 225 in the cap member and engage holes 226 and 227 in members 211 and 210, respectively. As screws 223 are tightened downward, central portion 222 pushes against septum 218 causing it to bulge outwardly. The outward bulging of septum 218 seals the septum against the inner surfaces of the cavity in stem 11 and against spacer 238, effecting closure of the stem until assistance in replacing the leaking principal septum can be obtained.

If septum 218 is provided with precut holes or slits aligned with the openings in the primary septum and holes 23 and 244 in the pressure plate 22 and spacer member 238, respectively, 8 GB 2 143 134 A 8 continued access may be provided to the circulatory system while the back-up septum is in place. In such case, the depressed portion 242 of 55 spacer member 238 allows septum 218 to function in the form of a floating diaphragm. This permits the septum to flex as the needles are inserted or removed, thereby facilitating insertion and removal of a needle or needles into the blood 60 access device and reducing friction or abrasion of the back-up septum caused by passage of the needle therethrough. The configuration of spacer member 238, including a central portion 242, is preferred over a simple ring having the configuration of outer ring 240 because central portion 242, while providing some space for septum 218 to flex downwardly, substantially fills the dead space between pressure plate 22 and back-up septum 218, thereby reducing the volume in which blood leaking through the 70 principal septum may collect.

Alternate Back-Up Septum System As an alternate to the back-up septum clamp as described above, a back-up septum 260 may be held within the stem cavity of device 10 by means of a compression ring 262 and a retaining ring 266, as shown in Figs. 37 and 38. To do so, the upper portion of the cavity in stem 11 is provided with a groove 264 in which a retaining ring similar to, but slightly larger than, ring 24 may be held. The back-up septum system of this alternative embodiment also employs the spacer 238 which is shown in Figs. 35 and 36.

The compression ring 262 conforms generally to the shape of the T-stem cavity and has a thickness such that, when retaining ring 266 is in place, the compression ring exerts sufficient pressure on septum 260 to cause the septum to seal the cavity opening.

By providing septum 260 with openings therethrough, such as slits 270, continued access to the circulatory system can be achieved.

Septum 260 may, but need not, have a side groove carrying an elastomeric ring similar to the construction of preferred septum 118.

Implant Cap Implantation of the blood access device is device so that stem 11 is pulled up through the second skin opening. To accomplish this without filling the cavity in stem 11 with tissue or blood, device 10 is preferably provided with a hemispherical cap 250 shown in Fig. 39 and in phantom in Fig. 17, which is used to cover stem 11 during implantation.

Cap 250 is a generally hemispherical member having a lower protrusion 252 which fits into the cavity of stem 11. Member 250 also has a tab 254 on the top thereof defining an opening 256 through which suture material 258, wrapped about device 10, may be passed. The winding of the suture material, as shown in Fig. 39, permits a surgeon to pull the device 10 into place in the second skin opening as described in the previous paragraph.

Claims (5)

1. A needle assembly for a septum closed blood access device, the assembly comprising a body member having a pair of substantially parallel hollow needles extending downwardly from said body member and a pair of substantially parallel tubing connector members extending outwardly from said body member, said body member further having a pair of channels therethrough, each said channel extending between one of said needles and one of said tubing connectors and providing fluid communication therebetween, said channel diverging outwardly between said needles and said tubing connectors such that the needle centers are closer together than the tubing connector centers.

2. A needle assembly in accordance with claim 1 wherein said tubing connectors extend from said body member at substantially right angles from said needles.

A needle assembly in accordance with claim 1 or 2 wherein said channels diverge outwardly by means of a nonconcentric tapered bore.

4. A needle assembly in accordance with claim 1, 2 or 3 wherein said needles are provided with a surface lubricant.

5. A needle assembly in accordance with any of claims 1 to 4 wherein the needles each have a rounded sealed lower end and plurality holes preferably accomplished by cutting a first opening 100 through the lower sides thereof, one above the through the skin into the body, connecting the device to the circulatory system, tunneling under the skin to a second opening through the skin and pulling the device through the tunnel by means of suture material wound about the body of the other, and wherein the needles are aligned within said assembly such that said holes enter said septum along the axis of precut slits in the septum.

Printed in the United Kingdom for Her Majesty's Stationery Office, Demand No- 8818935. 2/1985. Contractor's Code No. 6378. Published by the Patent Office. 25 Southampton Buildings, London, WC2A lAY, from which copies may be obtained.