U.S. patent number 3,826,257 [Application Number 05/272,077] was granted by the patent office on 1974-07-30 for prosthetic shunt.
Invention is credited to Theodore J. Buselmeier.
United States Patent |
3,826,257 |
Buselmeier |
July 30, 1974 |
PROSTHETIC SHUNT
Abstract
A prosthetic device partially implantable in the human body for
repeated intermittent access to the blood in the circulation
system, the prosthetic device comprising a subcutaneous U-shaped
shunt of preshaped Silastic, the ends of the U-shaped shunt having
tubular tips or other means for connection with an artery and a
vein to shunt blood from the artery to the vein; at least one
access tube connected with the shunt between the ends thereof and
in blood-flow communicating relation, at least the distal end of
the access tube to be located at the exterior of the person's skin,
and a removable plug entirely filling the full length of the access
tube and being removable to obtain access to the blood in the shunt
tube.
Inventors: |
Buselmeier; Theodore J.
(Minneapolis, MN) |
Family
ID: |
23038300 |
Appl.
No.: |
05/272,077 |
Filed: |
July 14, 1972 |
Current U.S.
Class: |
604/8; 604/175;
604/513; 604/507 |
Current CPC
Class: |
A61M
1/3655 (20130101) |
Current International
Class: |
A61M
39/10 (20060101); A61M 39/00 (20060101); A61M
1/36 (20060101); A61m 005/00 () |
Field of
Search: |
;128/214R,214B,214.2,334R,348,350 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Other References
AMCI Catalogue 1960, pp. 63-64 relied on. .
Quinton et al., Trans. ASAIO Vol. VIII, 1962, pp. 236-243..
|
Primary Examiner: Truluck; Dalton L.
Attorney, Agent or Firm: Palmatier; H. Dale
Claims
What is claimed is:
1. A prosthetic device for human implantation, comprising:
a U-shaped arterio-venous shunt tube of resiliently yieldable
material and having juxtaposed ends extending in similar directions
for subcutaneous flow connection to an artery and to a vein and
said shunt tube also having an intermediate portion in unbroken and
continuous flow connection with such juxtaposed ends to constantly
circulate blood between such ends; and
an access tube having a proximal end interlumenally and fixedly
connected in continuous free flow communication to said shunt tube
and a distal end through which access to the blood may be obtained,
and a closure for the access tube situated thereon.
2. The prosthetic device according to claim 1 and said ends having
means including stiff tubular tips on the ends of the shunt tube,
the distal ends of said tips being convergently tapered toward the
ends thereof to fit within the lumens of the artery and vein.
3. The prosthetic device according to claim 1 and wherein said ends
have means including a skirt of flexible material attached to the
ends of the shunt tube and adapted for direct connection to the
walls of the vein and artery.
4. The prosthetic device according to claim 1 and including a
second such access tube adjacent said first mentioned access tube
and also having a proximal end interlumenally and fixedly connected
in continuous free flow communication to said shunt tube and a
distal end through which access to the blood may be obtained, and a
second closure for the second access tube situated thereon.
5. A prosthetic device for human implantation, comprising:
a preshaped arterio-venous shunt tube having juxtaposed ends
extending in generally similar directions with means for
subcutaneous flow connection to an artery and to a vein and having
an intermediate portion in unbroken and continuous flow connection
with such ends to constantly circulate blood between such ends;
and
an access tube having a proximal end interlumenally and fixedly
connected in continuous free flow communication to said shunt tube
and a distal end through which access to the blood may be obtained,
and
operable closure means for said access tube located thereon and
effective at the interlumenal connection between the access tube
and the shunt tube to alternately exclude blood from and allow flow
of blood through the proximal end of the access tube while
permitting continuous circulation of blood through said
intermediate portion of the shunt tube and between the ends
thereof.
6. A prosthetic device for human implantation, comprising:
a U-shaped arterio-venous shunt tube with juxtaposed ends extending
in similar directions for subcutaneous flow connection to an artery
and to a vein, and the U-shaped shunt tube having a bight
intermediate the juxtaposed ends and also having an offset between
the bight and the ends to permit superficial positioning of the
bight; and
an access tube having a proximal end interlumenally and fixedly
connected in continuous free flow communication to the bight of the
shunt tube and a distal end through which access may be obtained,
and a closure for the access tube situated thereon.
7. A prosthetic device for human implantation, comprising:
an implantable U-shaped arterio-venous shunt tube of resiliently
yieldable material with juxtaposed ends for subcutaneous flow
connection to an artery and to a vein, the U-shaped shunt tube
having a bight intermediate said juxtaposed ends and the bight of
the shunt tube lying substantially in a plane oblique to the
juxtaposed ends;
an access tube having a subcutaneous proximal end connected in free
flow communication to the shunt tube and to extend through the skin
to the open distal end through which access to the circulation may
be obtained, the access tube extending substantially in said plane
to permit superficial positioning of the distal end of the access
tube; and
a closure for the access tube situated thereon.
8. The prosthetic device according to claim 7 and including a
second access tube lying substantially in said plane in spaced
relation with said first mentioned access tube and also connected
in free flow communication to the shunt tube.
9. A prosthetic device for human implantation, comprising:
an implantable U-shaped arteriovenous shunt tube of resiliently
yieldable material having juxtaposed ends for subcutaneous flow
connection to an artery and to a vein and having a bight
intermediate said ends, each of the ends and the bight of the shunt
tube carrying continuous blood flow; and
an access tube connected in free flow communication to the shunt
tube adjacent the bight and having a distal end offset with respect
to the juxtaposed ends of the shunt tube to remain superficially of
the person and provide access to the blood continuously flowing in
the shunt tube.
10. The prosthetic device according to claim 9 and the distal end
of the access tube being disposed at an oblique angle with respect
to the juxtaposed ends of the shunt tube.
11. The prosthetic device according to claim 9 and the distal end
of the access tube being oriented generally parallel to the
juxtaposed ends of the shunt tube and being spaced to one side of
said juxtaposed ends to remain superficially of the person.
12. The prosthetic device according to claim 9 and including a
second access tube also connected in free flow communication to the
shunt tube and adjacent the bight thereof and also spaced from said
first mentioned access tube, the distal end of the second access
tube also being offset with respect to the juxtaposed ends of the
shunt tube.
13. In the art of obtaining access to the blood in a human body,
the method steps consisting of subcutaneously implanting a U-shaped
arterio-venous shunt tube of resiliently yieldable material having
juxtaposed ends extending in similar directions and an intermediate
portion in unbroken and continuous flow connection with such
juxtaposed ends and also having an access tube with a proximal end
interlumenally and fixedly connected in continuous free flow
communication to said shunt tube and a distal end through which
access into the shunt tube may be obtained and a closure for the
access tube and situated thereon, entirely in the body and
anastomosing the juxtaposed ends of the shunt tube to an artery and
to an adjacent vein respectively while allowing the distal end of
the access tube and at least a portion of the closure therefor to
remain superficially of the body for connection to external
blood-receiving or supply means.
Description
BACKGROUND OF THE INVENTION AND PRIOR ART
Men have felt the need to obtain access to the circulatory system
since the very earliest times when blood-letting was popular.
Subsequently, access has become more important for the repeated
administration of medicines and other fluids; and more recently,
since the early 1940's, access has been important for the process
of hemodialysis.
Hemodialysis is a process whereby blood is removed from an
individual, passed through an artificial kidney machine, sometimes
referred to as a dialyzer, and then subsequently returned to the
body so that the continuous and consecutive passage as well as
purification of segments of the blood through a cleaning machine is
allowed over a 6 to 8 hour period. Although the first artificial
kidney machine was only used on animals and was subsequently
discarded, in 1941 Culf designed an artificial kidney to be used in
humans. The principal limitation at that time was the inability to
repeatedly gain access to the blood of the circulatory system over
a long period of time. Until 1961, the techniques used provided
only a very short term access, measured in hours or days, to the
blood in the human circulatory system.
In 1961, the Quinton-Scribner prosthesis was developed and
subsequently modified to obtain a rather long term access to the
blood in the circulatory system. The Quinton-Scribner shunt
utilized a pair of small and relatively stiff tubes or vessel tips
respectively inserted into an artery and a nearby vein. These tips
are attached to larger lengths of Silastic tubing which are brought
out through the skin, and are then connected together by a
connector so that these Silastic tubes can be separated from each
other and respectively connected to the supply and return ducts of
the dialysis machine. Ordinarily, these Silastic tubes which are
brought out through the person's skin have an overall length of
approximately 35 to 40 cm, and an internal diameter of
approximately 0.104 inches. At the time of dialysis, the two
Silastic tubes are separated and one of the tubes is connected to
the dialysis machine so that blood could flow from the tube
connected to an artery, through the machine and be constantly
returned through the tube connected to the vein; and no alternative
circulatory pathway is provided while the two tubes are separated
and attached to the machine. When the dialysis is completed or
terminated, the two Silastic tubes are clamped to terminate flow,
disconnected from the machine, and then interconnected to one
another so that when the clamps are released, blood may begin to
flow through the length of tubing from the artery to the vein.
This Quinton-Scribner prosthesis is prone to many problems, mainly
because of thrombosis and infection. The thrombosis resulted from
the relatively long tubing which provided a good deal of resistance
to flow of blood, and thrombosis often necessitated the removal and
replacement of the Quinton-Scribner prosthesis to a totally
different location or in a more proximal location in the same limb.
Infection resulted around the materials which protruded from the
skin, and even around the materials which were inserted in the
blood vessel. Unexpected trauma of voluntary disconnection of the
long and cumbersome lengths of tubing, also provided for
exsanguination in some cases. It has been postulated that the
infection and indeed also the thrombosis may have been contributed
to a large extent by the movement of this cumbersome external loop
which could not be very easily totally immobilized between dialysis
treatments.
Of course, cosmetics was also a problem with the Quinton-Scribner
prosthesis. However, regardless of problems encountered, the
prosthesis was practical and was able to be used over relatively
long periods of time for repeated intermittent dialysis
treatments.
Realizing the drawbacks of the Quinton-Scribner prosthesis, Brescia
and Cimino developed a new technique in 1966 for repeated
intermittent access to the circulation. They attached an artery
(high pressure system) to a vein (low pressure system) through a 5
to 10 millimeter anastomosis (connecting window), thereby producing
an arteriovenous fistula. After a 2 to 3 week maturation period in
which the venous walls dilated and thickened, it is possible to do
needle cannulation (insertion of a needle in the vessel) in the
vein close to the anastomosis for supply to an artificial kidney
machine, and also do needle cannulation at a portion more proximal
to the heart for return of the blood to the body from the kidney
machine. As a result of this subcutaneous connection without any
synthetic prosthesis, enough vein dilation occurred so that the
needles could be inserted for flow to and from the machine.
However, there were certain drawbacks in this Brescia-Cimino
technique. Firstly, the arteriovenous fistula required
approximately 3 weeks to a month to develop. Secondly, the fistula
required that the patient have the placement of two large needles
each time dialysis was required. Thirdly, the veins were
occasionally damaged by the needle sticks, and clots were
encountered. Fourthly, infection is said to have developed and been
promoted by the shunt from the artery to the vein. Fifthly, there
has been a question of the contribution of the fistula to cariac
failure when the shunts were too large. Furthermore, the creation
of the arteriovenous fistula is a somewhat difficult operation
which required a highly skilled surgeon. This Brescia-Cimino
technique was a giant stride over the Quinton-Scribner prosthesis
and allowed hemodialysis to proceed through many, many consecutive
treatments without anywhere near as numerous complications of
thrombosis or infection as had been encountered previously.
However, the medical centers which deal with acute patients who
need dialysis immediately and such centers which deal with home
dialysis and its training, often have difficulty with patients and
their families who do not wish to place needles in the vein for
dialysis. Further, the acute patients require immediate dialysis
and cannot be allowed the time necessary for the proper development
of the arteriovenous fistula.
SUMMARY OF THE INVENTION
This prosthetic shunt has been devised to eliminate most of the
disadvantages of the prior devices and techniques. The present
invention includes a preformed U-shaped shunt tube of a relatively
soft and resiliently yieldable material which is self-supporting
and resiliently resistive to collapse, and a suitable material used
in the shunt tube is a material known by its name as Silastic. The
opposite ends of the shunt tube which extend in the same direction,
have relatively stiff, but resiliently yieldable connector tubes or
vessel tips telescopically received therein to be respectively
cannulated into an artery of a person's limb, specifically his
forearm, and into an adjacent vein. It is expected that, in most
instances, the entire U-shaped shunt tube will be subcutaneously
implanted upon cannulation into the proximal vein and artery, while
the distal portion of the same vein and artery are tied off.
The present invention has at least one and in many cases two
separate access tubes connected to the shunt tube between the ends
thereof and extending transversely therefrom so that the distal
ends of the outlet tubes may project outwardly of the surface of
the skin of the forearm. These outlet tubes have flow communication
with the lumen of the U-shaped shunt tube, and normally the access
tubes carry a closure plug having an intralumenal portion extending
the full length of the access tube, but without infringement into
the lumen of the shunt tube. The extralumenal portion of the plug
forms a gripping cap facilitating removal of the plug and also
incorporating an eyelet by which a safety wire retains the plug in
the access tube, the wire being also attached to a loop or eyelet
formed integrally of the access tube. Alternately, the ends of the
shunt tube may be skirted with the flexible film or fabric material
such as a Dacron type skirt which allows anastomosis to the
vessels.
It will be appreciated that the end portions of U-shaped shunt tube
are parallel to lie in a plane and oblique to the bight portion of
the shunt tube which may overlie one of the bones in the forearm.
The access tube or tubes lie in the plane of the bight portion of
the shunt tube so that the access tubes may normally protrude
through and outwardly of the skin of the limb. Alternatively, the
U-shaped shunt tube may have an offset between the end portions and
the bight so that only the portions of the shunt adjacent to the
vessels are subcutaneously implanted while the intermediate portion
and the entire access port or ports are superficially
positioned.
The access ports may be used singly or simultaneously, depending
upon the purpose being accomplished and the type of equipment being
used with the present invention. A single access tube may be
utilized with one type of dialysis machine blood supply system
which requires only one access location, alternately drawing blood
from and returning blood to the shunt tube through the single
access tube. Additionally, the forms of shunt with one or two
access tubes may be used in non-uremic patients requiring
leukapheresis, the infusion of caustic substances such as
sclerosing high calorie solutions (hyperalimentation) or irritating
antibiotics, etc. Furthermore, either type of shunt, with a single
access tube or double access tubes may be utilized for arterial
blood sampling without the need for arterial puncture.
In the case of the prosthetic device using two access tubes, one of
these tubes will be positioned closer to the artery and the other
tube will be closer to the cannulated vein, the former access tube
acting as the blood outlet for supplying blood to the artificial
kidney machine, and the other access tube serving to simultaneously
return the blood to the shunt and the circulatory system. Of utmost
advantage is the fact that, unlike the situation in the
Quinton-Scribner prosthesis, the flow through the shunt is
maintained at all times, while the outlets are plugged, while
connecting or disconnecting the shunt to the machine, and even
while supplying and returning blood to and from the machine. A
portion of the blood which returns from the dialysis machine into
the shunt may recirculate through the shunt and back out for
recirculation again through the dialysis machine. This feature is
particularly valuable in preventing spasms in the supplying vessel,
and also allows the re-exposure of the segments of the blood to the
outside influence, as of the dialysis machine. It is particularly
significant that this recirculation flow pattern produces a greater
large particle (in the range of 300 to 2,000 molecular weight
commonly referred to as "middle molecule") removal as compared to
the removal of smaller particles (in the range of 0 to 300
molecular weight), the larger particles being mainly membrane
dependent and the smaller particles being mainly flow dependent for
their major removal rate limiting factors.
It will be recognized that a significant advantage of the present
invention is the relative ease of surgical insertion into the
patient's limb. A large percent of the small prosthetic device is
subcutaneously implanted. As a result, there is considerably less
exposure to outside influences tending to move the tubes and a
greatly improved cosmetic effect. Because the shunt tube is quite
short and has a smoothly curved U-shape, the tube has considerably
less resistance and greater intrinsic flow of blood therethrough,
tending to minimize any sludging or clotting. This, of course,
results in improved longevity as a result of there being less
chance of clotting and infection. There is immediate access to the
circulation without need for needle cannulation or maturation
development. This prosthetic device is adaptable to either a single
port or double port blood pump supply system.
It is particularly significant that the present invention functions
satisfactorily even in non-uremic patients who do not have the
anticoagulant toxins that uremic patients possess. In such
non-uremic patients, there is a tendency for more clotting, but the
present invention functions quite satisfactorily even with these
non-uremic patients, an advantage which has not been generally
observed with placement of prosthetic devices in non-uremic
patients.
BRIEF DESCRIPTION OF DRAWINGS
FIG. 1 is a perspective view of a person's forearm with the
prosthetic device implanted.
FIG. 2 is a view similar to FIG. 1, but with portions of the
forearm cut away in order to illustrate the present invention and
its intended use.
FIG. 3 is a side elevation view, partly broken away for clarity of
detail, of the present invention.
FIG. 4 is a longitudinal section view of the present invention,
taken on a section line as indicated at 4--4 of FIG. 3.
FIG. 5 is an enlarged section view of the invention similar to FIG.
4, but showing the expected circulation in the shunt.
FIG. 6 is a top plan view of a modified form of the invention.
FIG. 7 is a side elevation view of a second modification of the
present invention.
FIG. 8 is a top plan view of the form of the invention illustrated
in FIG. 7.
FIG. 9 is a top plan view of another modified form of the
invention.
FIG. 10 is a plan view of still another modification of the
invention.
DETAILED DESCRIPTION OF THE INVENTION
Although the prosthetic device incorporating the present invention
is illustrated in the drawings as implanted in the forearm, it will
be understood that this device may be implanted in any of the limbs
of the person, and may also be implanted in other appropriate parts
of a person's body, such as in his leg or neck.
In FIG. 1, a person's forearm is illustrated with the prosthetic
device, indicated in general by numeral 10, implanted. Only a small
portion of the device 10 will normally be in a superficial
position. Only the access tubes 16 protrude through surgically
formed openings 0 in the forearm F. The access tubes 16 may be used
singly or together in order to obtain the desired access to the
circulation. Normally the access tubes are closed by plugs 13. Only
the head or extralumenal protrusion 14 of the plugs is normally
visible on the access tubes 16. These plugs 13 will be removed, as
necessary, in order to connect the access tubes to a dialysis
machine or other equipment to be used.
As illustrated in FIGS. 2, 3 and 4, the prosthetic device 10
comprises a shunt tube 15 constructed of relatively soft,
resiliently yieldable and self-supporting material resistant to
collapse. Certain plastic materials which are molded have this
desired characteristic and a specific example is a product known as
Silastic. The shunt tube 15 has a smoothly curved U-shape wherein
the bight 15a of the tube lies in a plane which is obliquely
oriented with respect to the parallel ends 15b and 15c. When
implanted, the curved or bight portion 15a of shunt 15 will usually
overlie a bone in the forearm and the preformed configuration of
the shunt will be substantially maintained with small variations,
according to the characteristics of the particular forearm or body
in which the device 10 is being implanted.
The prosthetic device 10 also includes one or more access tubes 16,
two of which are illustrated in FIGS. 1 - 5. The access tubes 16
are formed of the same relatively soft, resiliently yieldable and
self-supporting material resistant to collapse of which the shunt
tube 15 is constructed, and the tubes 16 may be molded integrally
of the shunt tube 15 and in one piece therewith. The tubes 16 are
in free flow communication with the interior of the shunt tube 15
so that there can be substantial flow of blood between the shunt
tube 15 and the access tubes 16 without any material
resistance.
The ends 15c and 15b of the shunt tube are provided with means for
subcutaneous and free flow connection with the proximal portion of
an artery A.sub.p and the proximal portion of a vein V.sub.p, and
such means as illustrated in FIGS. 1 - 5 comprise relatively stiff,
resiliently flexible tubular tips 17 constructed of any suitable
material such as a plastic known as Teflon. The tips 17 will
provide flow communication between the shunt 15 and the artery
A.sub.p and vein V.sub.p, and the tips 17 are confined within the
ends 15b and 15c, and the tips 17 are confined within the ends 15c
and 15b of the shunt 15. The resilient Silastic of the shunt 15
grips and retains the tips 17 in place. When the implant is
actually made in a person's forearm as illustrated in FIG. 2, tips
17 of a suitable size so as to match the sizes of the lumen of the
artery and vein are selected, and, after being inserted, the ends
of the artery A.sub.p and vein V.sub.p are tied onto the tips 17
and the tie is also used to tie the Silastic shunt 15 onto the tips
17 so as to assure that the proper assembly will be continuously
maintained.
It should be parenthetically noted that, although the distal artery
A.sub.d is severed from the proximal artery A.sub.p, and similarly
the distal vein V.sub.d is severed from the proximal vein V.sub.p,
this will not result in any shortage of blood-carrying capacity to
the hand because of the existence of other generally parallel
arteries and veins to provide adequate circulation. The distal vein
V.sub.d and the distal artery A.sub.d which have been severed are
simply tied off and allowed to be non-functional.
As best illustrated in FIG. 3, it is preferable that the access
tubes 16 extend obliquely of the plane in which the ends 15b, 15c
of the U-shaped shunt tube 15 lies. Only the distal end of the
access tube will protrude through the skin of the forearm as
illustrated in FIG. 1.
In order to accommodate the difference in the size of the lumen of
shunt tube 15 as compared to the lumen size in the artery or vein
to which the tube 15 is connected, the tips 17 are simply tapered
convergently toward the connection with the vein or artery because,
ordinarily, the size of the vein or artery is somewhat less than
the size of the shunt tube 15.
The access tubes are provided with exterior eyelets or loops 18
integral with the tubes; and the heads 14 of plugs 13 have
transverse holes 14a therethrough. A safety line or wire 16b may be
threaded through hole 14a and the adjacent eyelet 16a and tied to
securely anchor the plug 13 in tube 16.
After the prosthetic device has been implanted, and the two access
tubes 16 have been connected to the dialysis machine which is shown
diagrammatically in FIG. 5 and indicated in general by letter D,
the access tube 16.1 serves as the outlet from shunt tube 15 for
supplying blood to the dialysis machine D, and the access tube 16.2
serves the function of returning the blood to the shunt 15 from the
dialysis machine. It will be understood that the dialysis machine
incorporates a suction pump to actually draw blood from the access
tube 16.1 and from the adjacent shunt tube 15 and artery A.sub.p as
indicated by the arrows S. In addition, a portion of the blood
continues to flow from the artery A.sub.p through the shunt 15 and
directly into the vein V.sub.p as indicated by the arrows F. The
same blood pumped or drawn into the dialysis machine D is returned
into the circulation through access tube 16.2 as indicated by the
letter S. A portion of the blood which is returned to the shunt 15
through access port 16.2 may be recirculated and actually flow from
the access tube 16.2 to the access tube 16.1, counter to the
direction of flow F and in the direction of arrows R as illustrated
in FIG. 5. This function of recirculating the blood back into the
dialysis machine as indicated by the blood flow arrows R provides
substantial advantages in connection with this prosthetic device
10. Firstly, the adaptability for recirculation prevents spasm in
the supplying vessel or artery A.sub.p. Secondly, the recirculation
would also allow for re-exposure of segments of the blood to the
dialysis machine or other outside influence for treatment being
carried on.
It may be desirable, in many instances, to utilize only one of the
access tubes 16. Certain blood treating machines require only a
single access port through which blood is drawn into the machine
and intermittently returned to the circulation. A single access
tube may be utilized while the other tube 16 remains closed, as for
non-uremic patients requiring hyperalimentation, and antibiosis.
Access through the ports also facilitates leukapheresis. A single
access tube may be used for simply sampling the arterial blood
supply.
It will be noted that the access tubes 16 are provided with
external eyelets 18, and the plug heads 14 are also provided with
holes 19 so that a safety line or wire 20 may be used to tie the
plug in the respective access tube when the access tubes are not
actively being used to obtain access to the circulation. It will be
understood that the safety wire may be simply clipped when the plug
is to be removed and then subsequently replaced.
A modified form of the prosthetic device is illustrated in FIG. 6
and is indicated in general by numeral 25. This device is very
similar to that illustrated in FIGS. 1 - 5 and is constructed of
identical material. The prosthetic device 25 has a shunt 15',
connecting tubes or tips 17', but the prosthetic device 25 only has
a single access tube 16'. Of course, the access tube is provided
with a removable closure or plug 13' substantially identical to
that previously described. Of course, the decision to implant a
prosthetic device with one access tube or two access tubes will be
made according to the type of equipment that is expected to be
used.
Another modified form of the prosthetic device is illustrated in
FIGS. 7 and 8 and is indicated in general by numeral 30. This form
of device has a shunt tube 15.1 which is similar to the shunt tube
15 of FIGS. 1 - 5, but has an offset 15.2 in each of the end
portions so that the bight 15.3 of the tube may be superficially
located while the ends of the shunt are subcutaneously attached to
the blood vessels. The bight 15.3 and the access tubes 16.3 will be
superficially located. The shunt tube 15.1 protrudes through the
skin of the person's forearm approximately at the offset portion
15.2.
The form of the device 30 illustrated in FIGS. 7 and 8 will have
certain advantages such as ease of installation, particularly in
limbs of persons who are minimally developed.
The form of the prosthetic device 31 illustrated in FIG. 9 is
substantially identical to that illustrated in FIGS. 7 and 8 except
that only a single access tube 16.4 is connected to the bight 15.4
of the shunt tube 15.5. In this form the end portions also have
offsets 15.6 so that only the ends of the shunt will be implanted
and subcutaneously attached to the blood vessels.
In the form of the invention illustrated in FIG. 10, the prosthetic
device 32 is substantially identical to that illustrated in FIGS. 1
- 5 and has the shunt tube 15.7 and one or more access tubes 16.5
connected to the shunt tube. In this form, a flexible Dacron fabric
skirt 33 is attached securely, as by welding, to each end of the
shunt tube. This skirt will flare divergently from the end tube
15.7 to enlarged sizes at the distal end of the skirt. The skirt
will be cut off according to the size of the vessel to which it
will be attached and then is attached by stitching to the vessel.
Of course, this form of connection between the shunt tube and the
vessels allows more flexibility in relation to the size of vessels
with which the shunt may be utilized.
It will be seen that I have provided a new and improved prosthetic
device for repeated intermittent blood access, principally
including a shunt tube for connection between an artery and an
adjacent vein, offering minimal resistance to flow of blood and
therefore a minimal likelihood of thrombosis. It is intended that,
in some instances, the entire U-shaped shunt tube will be
implanted, while in other instances only the portion adjacent to
the vessel is subcutaneous in location. Access tubes are connected
to the shunt tube and protrude transversely therefrom so that the
distal ends of the shunt tubes will be located at the exterior of
the skin, providing ready and easy access to the circulation in the
shunt tube. Suitable openable closures are provided for the access
tubes and, in the form illustrated, plugs are used throughout the
whole length of the access tubes without infringing into the lumen
of the shunt tube, thereby minimizing any likelihood of thrombosis
at this location. The prosthetic device may be permanently
implanted and used repeatedly to obtain blood access without
requiring any further cannulating of the veins or arteries.
* * * * *