US 20070123811 A1
A hemodialysis and vascular access system comprises a subcutaneous composite PTFE silastic arteriovenous fistula having an indwelling silastic venous end which is inserted percutaneously into a vein and a PTFE arterial end which is anastomosed to an artery. Access to a blood stream within the system is gained by direct puncture of needle(s) into a needle receiving site having a tubular passage within a metal or plastic frame and a silicone upper surface through which needle(s) are inserted. In an alternate embodiment of the invention, percutaneous access to a blood stream may be gained by placing needles directly into the system (i.e. into the PTFE arterial end). The invention also proposes an additional embodiment having an arterialized indwelling venous catheter where blood flows from an artery through a tube and a port into an arterial reservoir and is returned to a vein via a port and a venous outlet tube distinct and distant from the area where the blood from the artery enters the arterial reservoir. The site where blood is returned to the vein is not directly fixed to the venous wall but is free floating within the vein. This system provides a hemodialysis and venous access graft which has superior longevity and performance, is easier to implant and is much more user friendly.
1. A hemodialysis and vascular access system wherein:
said system comprises a first portion comprising a tube and a second portion comprising a catheter and wherein:
said tube is provided from a material which can be sutured to the artery with a first end of said tube adapted to be coupled to an artery; and
said catheter is adapted to be inserted within a vein at an insertion site, with a first end of the catheter having an opening adapted to be within the vein itself and wherein the opening in the first end of said catheter is distant from the insertion site and
said tube and said catheter being adapted to be entirely subcutaneous in use and
configured to avoid, in use, a reservoir therein.
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16. The hemodialysis and vascular access system of
17. A hemodialysis and vascular access system to shunt blood between a vein and an artery, said system having a single lumen comprising:
a tube having first and second ends, said first end adapted to be anastomosed to said artery; and
a catheter, comprising tubing having a first end and a second end, said second end being connected to said second end of said tube;
said catheter having a site for entering said vein, said site being away from said first end of said catheter so that, in use, said first end can be located downstream in said vein;
and needle receiving sites between said first end of said tube and said first end of said catheter;
said tube and said catheter being adapted to be entirely subcutaneous in use and configured to avoid, in use, a blood reservoir therein and to provide continuous blood flow.
18. The hemodialysis and vascular access system of
19. The hemodialysis and vascular access system of
20. The hemodialysis and vascular access system of claims 17, wherein said second end of the catheter comprises an enlarged portion configured to lock with said second end of the tube.
21. The hemodialysis and vascular access system of
22. The hemodialysis and vascular access system of
23. The hemodialysis and vascular access system of claims 1, wherein said catheter comprises a cuff adapted for sewing to the vein.
24. The hemodialysis and vascular access system of
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32. A hemodialysis and vascular access system, comprising:
an arterialized indwelling venous catheter having a first portion provided from a material which is biocompatible with an arterial system, has a nonthrombogenic characteristic, which is adapted for attachment to an arterial system and a catheter section, with a first end of said first portion adapted to be coupled to an arterial system and a portion of the catheter section adapted to be inserted within a venous system at an insertion site, said catheter section portion having an outside diameter which is less than an inner diameter of the venous system and having at least one opening in an end thereof with at least one of the at least one openings in the catheter section portion adapted to be within the venous system itself and wherein the at least one opening is distant from the insertion site such that, in operation, blood flows from the arterial system through the catheter and is returned to the venous system through the at least one opening and blood also flows through the vein uninterrupted around at least an outer portion of said catheter; and
at least one needle having a first end coupled to a hemodialysis device and having a second end adapted for insertion directly into the arterialized indwelling venous catheter to shunt the blood flow through the dialysis device.
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This application is a continuation of U.S. application Ser. No. 10/219,998 filed on Aug. 15, 2002, which is a reissue of U.S. application Ser. No. 08/835,316 filed on Apr. 7, 1997, now U.S. Pat. No. 6,102,884, which claims benefit under 35 U.S.C. Section 119(e) to U.S. Application No. 60/037,094, filed on Feb. 3, 1997, all of which are incorporated herein by reference in their entirety.
Currently, HD (hemodialysis) and vascular access for chemotherapy and plasmapheresis is achieved in one of several ways. Applicant's invention involves a new method and instrumentation for HD and vascular access designed to eliminate the problems of the prior methods and create a new, more durable, easier to use, vascular access system.
One prior art method involves a primary arteriovenous fistula. In this method, a native artery is sewn to a native vein creating a high flow system of blood in a vein which over time can be accessed with two hemodialysis needles attached to a dialysis machine. The problem with this method is that few patients are candidates secondary to anatomy and in others the veins or shunt fail to enlarge and mature properly even if the primary fistula remains patent. These arteriovenous fistulas also become aneursymol over time requiring revision.
Another method involves a subcutaneous prosthetic conduit (PTFE) in the shape of a tube which is sewn at either end to openings made in an artery and vein. This method causes recurrent stenosis at the venous outflow leading to thrombosis (i.e., graft closure) secondary to intimal hyperplasia at venous anastomosis. Thrombosis also occurs at needle puncture sites along the PTFE.
Another method involves a “tunneled” percutaneous dual lumen catheter which is inserted into a central vein. This causes recurrent thrombosis secondary to stasis of blood in the lumen (i.e., not a continuous flow system like an A-V fistula) and build up of fibrinous debris at the venous end. Further, the access end of the catheter protrudes through the skin making it cosmetically unappealing, cumbersome to live with, as well as more likely to become infected.
A further method involves the use of the Sorenson Catheter. This is a percutaneous (not tunneled) dual lumen catheter, placed into the central venous system, which is used to provide temporary access for the purposes of hemodialysis. These catheters are prone to kinking, clotting, infection, and poor flow rates.
A still further method of vascular access involves the “Port-a-cath”. This system of venous access, which utilizes a subcutaneous reservoir attached to a central venous catheter, is used for long term intervenous access for chemotherapy etc. (It is not intended for HD.) The ports are prone to clotting and must be continually flushed since they are a stagnant system.
Applicant's invention involves a vascular access system, known as the Squitieri Hemodialysis and Vascular Access System, which creates a continuous blood flow and which is easily accessed and resistant to clotting. These advantages provide ideal access for long term HD chemo or blood draws. An example, would be patients who are on coumadin which require weekly blood draws. This new system becomes less painful over time as the skin over the “needle access” site become less sensitive. The veins are spared repeated blood draws which results in vein thrombosis to such a degree that some patients “have no veins left” making routine blood draws impossible.
Among the more relevant prior art patents are U.S. Pat. Nos. 4,898,669, 4,822,341; 5,041,098; and, 4,790,826. None of the foregoing patents disclose a system having the features of this invention. U.S. Pat. No. 4,447,237 describes improvements in a valving slit which includes the provision of a flattened sleeve within an elastomeric body presenting opposed interior surfaces interengaged when the valving slit is in the closed condition and spaced apart when the valving slit is in the open condition.
A hemodialysis and vascular access system comprises a PTFE end which is sutured to an opening in an artery at one end and the other end is placed into a vein using any technique which avoids the need for an anastomosis between the silicone “venous” end of the catheter and the vein wall. The system comprises any material, synthetic or natural (i.e. vein) which can be sutured to the artery (i.e. preferably PTFE) at one end while the other end is composed of a material which is suitable for placement into a vein in such a way that the openings in the “venous” end of the system are away from the site where the graft enters the vein. The system may also be constructed of multiple layers of materials i.e. PTFE on the inside with silastic on the outside. The “Needle Receiving Site” may also be covered with PTFE to encourage self sealing and tissue in-growth.
A preferred embodiment comprises a combination of PTFE conduit sewn to an artery on one end of the system with the other end connected to a silastic-plastic catheter which can be percutaneously inserted into a vein via an introducer. The venous end may also be placed via open cut down. The seal around the system where it enters the vein may be “self sealing” when placed in percutaneous technique; it may be achieved with a purse string when done by open technique “cut down”; or, it may be sewn to the vein to create a seal with a “cuff” while the system continues downstream within the venous system to return the arterial blood away from the site of entry into the vein. The entire system can be positioned subcutaneously at the completion of insertion. This design is a significant improvement over existing methods because it avoids the most frequent complication of current HD access methods. By utilizing an indwelling venous end, one avoids creating a sewn anastomosis on a vein which is prone to stenosis secondary to neointimal hyperplasia. By having continuous flow through the silastic end of the catheter, thrombosis of these catheters can be avoided. Dialysis is made more efficient by decreasing recirculation of blood which accompanies the use of side by side dual lumen catheters inserted into a central vein. This invention not only benefits the patient but it also speeds dialysis thus saving time and money.
To summarize, the Squitieri Access System comprises a tube composed of PTFE and a silastic catheter. This tube is used to create an arteriovenous fistula. The PTFE end (arterial end) of the tube is sewn to an artery while the silastic catheter end is placed into the venous system by the Seldinger technique much like a standard central line. The entire system is subcutaneous at the completion of insertion. This system is a composite of the arterial end of a “gortex graft” joined to the venous end of a “permacath”. This system enjoys strengths of each type of access and at the same time avoids their weaknesses.
Accordingly, an object of this invention is to provide a new and improved vascular access system.
Another object of this invention is to provide a new and improved hemodialysis and vascular access system including an easily replaceable needle receiving site which has superior longevity and performance, is more easily implanted, more easily replaced, and is “user friendly” i.e. easily and safely accessed by a nurse or patient which is ideal for home hemodialysis.
A more specific object of this invention is to provide a new and improved Squitieri hemodialysis and vascular access system including a subcutaneous composite PTFE/Silastic arteriovenous fistula.
A further object of this invention is to provide a new and improved hemodialysis and vascular access system including a fistula utilizing an indwelling silastic end which is inserted percutaneously into the venous system and a PTFE arterial end which is anastomosed to an artery and including a unique needle receiving sites which are positioned anywhere between the ends and which have superior longevity and performance.
A further object of this invention is to provide a system constructed to preserve laminar flow within the system and at the venous outflow end to reduce turbulence and shear force in the vascular system to the degree possible.
A still further object of this invention is to provide a system wherein the arterial end (PTFE) may also be placed by percutaneous technique including one where blood entry holes are distant from the site where blood enters the veins.
The above and other objects of this invention may be more clearly seen when viewed in conjunction with the accompanying drawings wherein:
Referring to the drawings the Squitieri hemodialysis and vascular system, as shown in
The access site 20 includes an in line aperture 16, see
Along the length of the catheter specially constructed needle access sites 20 (
The needle access areas 20 which are designed to receive needles 15 etc. to allow access to the system are in line conduits with self-sealing material 25 which is here shown as a silicone member 25 which can be located beneath the skin surface. The silicone member 25 comprises an oval configuration exposed within the frame 26 for ease of puncture. The system may be accessed immediately after insertion without having to wait for the graft to incorporate into the tissues as is the case with the current methods of subcutaneous fistulas. These access areas 20 will protect the graft since they are uniformly and easily utilized requiring little training or experience. The “needle receiving” sites 20 are designed in such a way to preserve laminar flow as far as possible (i.e. not a reservoir arrangement). Needle receiver sites 20 may be connected to a system via “quick couple” 45 for easy exchangability, see
The open end portion 19 of the PTFE tube 10 is sewn to an opening in an artery 30, see
In this invention, the materials used may vary as specified herein. The system may be constructed of one or more specific materials. The arteries and veins used may also vary. Material may also be covered with thrombus resistant coatings (heparin, etc.) or biologic tissue. The system may in specific cases be “ringed” for support.
The same concept of using an arterialized venous access catheter may be applied to the use of long term indwelling catheters used to give chemotherapy etc., making the current ports obsolete as these new access systems will have a decreased thrombosis rate and they will no longer need to be flushed as continuous blood flow through the system makes thrombus formation unlikely. This will definitely cut down on costs since it will decrease nursing requirements in out patient settings, etc.
In alternate embodiments shown in
A housing 86 includes a top portion 86 a and a side portion 86 b. The top portion 86 a includes an aperture which surrounds and provides a means for accessing the oval silicone access site 90. This embodiment provides a quick assembly for a needle access site 71.
The Squitieri Hemodialysis/Vascular Access System avoids creation of a venous anastomosis, a revolutionary advancement, i.e. there is no site for neointimal hyperplasia at a venous anastomosis which accounts for the vast majority of PTFE arteriovenous graft failures (60-80%). This is accomplished by returning the blood into a larger vein via an indwelling venous catheter 42. The site of blood return to the venous system is not fixed to the vein wall where neointimal hyperplasia occurs with the standard PTFE bridge graft. This feature represents a tremendous advantage over the present grafts.
As a further advantage, the system is not stagnant and prone to thrombosis, i.e. constant flow through the new system avoids the problem of clotting inherent in indwelling dual lumen venous catheters which remain stagnant when not in use. It also avoids need to flush catheters with heplock thereby reducing nursing costs to maintain the catheter.
The Squitieri system avoids externalization of components which are prone to infection. Since dual lumen catheters exit the skin 14, they frequently lead to sepsis requiring catheter removal despite subcutaneous tunneling. This new access is entirely subcutaneous.
Very importantly the system proposed herein, avoids problems with the aspiration of blood from the venous system and “positional” placement through continuous flow. A frequent problem with dual lumen catheters is their inability to draw blood from the venous system due to clot and fibrinous debris ball-valving at the tip of a catheter. This new system receives blood directly from arterial inflow which ensures high flow rates needed for shorter, more efficient dialysis runs. It also avoids the frequent problem of the catheter tip “sucking” on the vein wall inhibiting flow to the dialysis machine and rendering the access ineffective.
The system avoids recirculation seen with dual lumen catheters resulting in more efficient and more cost effective dialysis.
The system avoids the need for temporary access with incorporation of “Needle Access Sites” 20. A-V fistulas and gortex grafts must “mature” for several weeks before use. This creates a huge strain on the patient as well as the doctor to achieve temporary access while waiting to use the permanent access. Temporary access is very prone to infection, malfunction and vein destruction. By placing sites 20 designed to receive needles 15 along the new access, the system may be used the day it is inserted.
The system avoids PTFE needle site damage with the incorporation of “Needle Access Sites” 20. Needle access directly into PTFE is presently uncontrolled and user dependent. Often, PTFE is lacerated by access needles. While this system may be accessed via the PTFE segment, the needle receiving sites are the preferred method. This leads to excessive bleeding which requires excessive pressure to halt the bleeding causing thrombosis of the graft. “Needle Access Sites” 20 on the Squitieri access system allow safe, quick, and easy entry into the system and avoid the complications inherent in placing needles directly into PTFE. It also avoids perigraft bleeding which will compress and thrombose the graft. By eliminating the long time needed to compress bleeding at the needle site, the system shortens dialysis runs.
The Squitieri system permits an easier, faster insertion technique. Only one anastomosis the arterial end and a percutaneous placement of the venous end is required. A modification allows the system to be sutured to the vein wall while the system tubing is floated down stream from this site where the system enters the vein 40. This saves operating room time at thousands of dollars per hour. The technique is easier with faster replacement. It avoids difficult and time consuming revision of venous anastomosis required to repair venous outflow occluded by neointimal hyperplasia. If the system malfunctions, the silastic catheter end 65 slips out easily and the arterial end of the outlet tube 53 is thrombectomized. New access sewn to the thrombectomized end of the outlet tube 53 of PTFE at the arterial end and the silastic venous end is replaced percutaneously via Seldinger technique or “open technique”.
The end result of the above advantages translates into superior patency rates and a decreased complication rate with this new system. Patients are spared the repeated painful hospitalizations for failed access as well as the emotional trauma associated with this difficult condition. The physicians are spared the dilemma of how to best treat these patients. This system will have a large impact on the current practice of vascular access in areas such as hemodialysis; plasmapheresis; chemotherapy; hyperalimentation; and chronic blood draws.
While the invention has been explained by a detailed description of certain specific embodiments, it is understood that various modifications and substitutions can be made in any of them within the scope of the appended claims which are intended also to include equivalents of such embodiments.