Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
~z~v~
This invention relates to medical devices and, more
particularly, to an improvement in devices that provide
access to the circulatory system of a living body.
There is a need in devices that provide access to
the circulatory system of a living body, for example, to tap
the blood supply for passing the blood externally of the body
through a blood dialyzer. An individual could re~uire the
use of a dialyzer over an extended period of time, and it is
desirable for devices to be available for implanting in the
body for immediate connection of catheters to the circulatory
system at any desired time. As implants, however, such devices
should be biologically compatible with the living tissues
surrounding them. In this connection, the devices should not
pxevent healing, irritate tissues or stimulate a prolonged
rejection response by the living body. Further, the devices
should be physiologically inert over prolonged periods of time
and should be mechanically strong and reliable. It is desir-
able that such devices in combination with at least the tips
of the catheters provide positive, error-free access to the
blood.
In United States Patent No. 4,015,601 which issued
on April 5, 1977 to the assignee of this invention, an access
device is described which provides means for forming fluid
communication between the outside and the circulatory system.
Such a device is uni-directional, i.e., allows fluid passage
in one direction at a time. Described herein is a device that
is duo-directional, i.e., provides access to the circulatory
system for simultaneous withdrawal and return of blood to
the system.
Although skilled and trained personnel, such as
doctors, nurses, and medical technicians, work with such
blood access devices, it is desirable that the possibility
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for human error in connecting and disconnecting the
catheters to the implanted blood access devices be mlnimized.
Accordingly, it is an object of this invention to
provide a system for joining catheters to implanted blood
access devices that will permit positive engayernent and
disengagement of the joined parts while maintaining the
valves of the devices in ~heir seated conditions.
It is another object of this invention to provide
a system of the foregoing type whereby the valves are rotated
by rotation of the catheters after such positive engagement
between the parts has been established.
It is a further object of this invention to provide
a system of the foregoing type whereby removal or disengage-
ment of the catheters from the joined condition of the
implanted access devices is prevented when the valves of the
devices are open.
The accomplishment of these and other objects of
the invention will become apparent from the following
description and its accompanying drawings of which:
~0 FIGURE 1 is a perspective view of a duo-directional
blood access device embodying various features of the inven-
tion and adapted for implantation in a living body;
FIGURE 2 is a vertical sectional view of the device
of FIGURE 1 taken along the line 2-2 and illustrating parts
nonaligned (valve closed! to prevent fluid communication
between parts;
FIGURE 3 is a view similar to FIGURE 2, but illustra~
ting parts aligned (valve open) for fluid communication and
illustrating one form of a catheter inserted in the device to
extend the communication externally of the body and also
illustratin~ structural features of the system that prevent
removal of the catheter when the valve is open;
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FIGURE 4 is a cross-sectional view of the device
taken along line ~-4 o~ FIGURE 3;
FIGURE 5 is an end view of the device with part
in section;
FIGURE 6 is a side view of a catheter receiving
member of the device;
FIGURE 7 is an end view of the member of FIGURE 6;
FIGURE ~ is a sectional view of a valve member of
the device;
FIGURE 9 is an end view of the device taken along
the line 9-9 of FIGURE 8;
FIGURE 10 is an alternative construction of a
catheter tip suitable for insertion in the device of FIGURE 3;
FIGURE 11 is a perspective view of a uni-directional
blood access device also embodying various features of the
invention and adapted for implantation in a living body;
FIGURE 12 is a catheter tip embodying features of the
invention for insertion in the device of FIGURE 11;
FIGURE 13 is an end view of the catheter tip of
FIGURE 12; and
FIGURE 14 is a vertical sectional view of the device
of FIGURE 11 taken along the line 1~-14 and illustrating
structural features that prevent the removal of the catheter
tip when the valve of the device of FIGURE 11 is open.
The features that provide a system for joining
catheters to implanted blood access devices in accordance
with the invention are first described in connection with a
duo-directional blood access device for ~mplantation in a
living body. Such duo-directional access device of the
invention includes three principal outer portions~ two of
which are generally parallel to one another and the other of
which is generally at right angles to the two parallel portions.
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Both parallel portions are tubes having open ends. Either
one may be inserted longitudinally in a blood vessel, the
other being available for connection to a bypass in the form
of a graft either upstream or downstream of the same blood
vessel. The third major portion is a housing with one end
open and the other closed, the housing containing a valve
for establishiny fluid communication with the blood in the
blood vessel. The valve is adapted to receive a dual-
conductor catheter which is used to establish a blood flow
line simultaneously in and out of the circulatory system.
The device is structured of materials that are biologically
compatible with the blood and tissues of a living body in
which it is inserted. At least all hlood contacting surfaces
are carbon. Further, the material is physiologically inert
over prolonged periods of time and is mechanically strong and
reliable, all of which is described in detail hereinafter.
Referring now to FIGURE 1, there is shown a blood
access device 13 having a pair of parallel conduits 15 and
17 and a housing 19 having a closed end 20, the conduits
being adjoined near the closed end. In this illustrated
embodiment, both the conduits 15 and 17 are round tubular
open-ended structures, and the housing 19 is generally
cylindrical in form. The conduits 15 and 17 are generally
parallel to one another and are generally at right angles to
the axis of the housing 19.
In FIGURE 2 it will be seen that several members
are mounted internally of the housing 19. Immediately inside
the walls of the housing 19 is a liner 21, and immediately
inside the liner 21 is a valve body 23. It will be noted
that the housing 19 is generally cylindrical with the inner
portion of the housing being tapered toward its closed end.
Both the liner 21 and valve body 23 are generally cylindrical,
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each having a closed end and an open end. The~ both taper
inwardly toward their closed ellds, the respec-tive tapers
conforming to that of the housing ln-terior. The liner 21
forms a SnUCJ or close-fitting relation with the internal
portion of the housing 19, as does the valve body 23 within
the liner 21. None-theless, the valve body is coaxially
rotatable within the liner 21 and housing 19, the liner being
fixed to the housing interior by a suitable epoxy or cement.
The liner 21 is dimensioned so that it will completely line
the interior wall of the housing 19 and fit against the
closed end of the housing. It is important that the valve
body 23 form a tight seal with the liner 21, and for this
reason, the closed end of the valve body 23 does not bottom
on the interior end of the liner 21. Clearance is provided
to assure adequate seating of the valve body within the liner
along the tapered interface to form, as will be described in
detail hereinafter, a li~uid and bacterial seal. Some very
slight differences in diameters of the respective parts can
be tolerated with this tapered structure. Preferably, both
the valve body 23 and the liner 21 are made of pyrolytic
carbon and -the housin~ 19 is made oE titanium, as Eully
described hereinafter.
FIGURE 2 shows the device 13 with the valve body
23 in the closed position, i.e., there is no fluid communica-
tion between the interiors of both the conduits 15 and 17 andthe interior of the valve body 23. To provide such fluid
communication between these interiors, the conduits 15 and
17 are provided with apertures 25 and 27 respectively through
the conduit walls. Although the conduits 15 and 17 are
generally parallel to each other, their points of adjoining
the housing are displaced from each other with respect to -the
axis of the housing 19, as well as being spaced away from the
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axis itself. Accordingly, the apertures 25 and 27 are
spaced apart from each other axially of -the housing 19, and
to complete the fluid communication to -the interior of the
valve body 23, there are provided ports 29 and 31 in the wall
of the valve body located to be alignable with the apertures
25 and 27 at a given rotative position of the valve body 23.
Referring briefly to FIGURE 3, such alignment is seen. Because
of the axial displacement of these apertures and their corres-
ponding ports, there is only one rotative position of the valve
body in which fluid communication will be established between
the interiors. Referring once again to FIGURE 2, the valve
body is shown with a 90 rotation from the position of align-
ment, but even at a 180 rotation from the position of align-
ment, it will be seen that fluid communication will not be
established. The apertures 25 and 27 are each defined by a
perimeter formed of a sharp edge 33 and 35 respectively of the
conduit walls.
The valve body 23 with its ports 29 and 31 is shown
separately in FIGURE 8. There it will be seen that a counter-
bore 37 is provided in the open end of the body. FIGURE 9 isa view looking into the open end of the valve body 23, and it
will be seen that a pair of grooves 39 and 41 are provided in
the inner surface of the counterbore 37. These grooves are
coterminous with the counterbore and extend in a direction
axially of the valve body.
The purpose of the counterbore 37 is to receive
and hold a cannula receptacle shown in FIGURES 7 and 8. This
receptacle includes a cylindrical body 45 and a top flange
47. The body 45 has an outside diameter that forms a snug
fit when the receptacle is inserted in the counterbore 37 at
the open end of the valve body 23.
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~ suitable epoxy or other cement is used to affix
the cannula receptacle 43 to the valve body 23 after the
desired rotative position of the receptacle with respect to
the valve body has been established. This desired position
involves a pair of grooves d 9 and 50 in the outer surface of
the body wall 45 extending in a direction axially of the
cannula receptacle. The grooves 49 and 50 are in the outer
surface of the body wall and are semi-circular in cross
section. The grooves 39 and 41 are in the inner surface of
the counterbore 37 are semicircular in cross section and are
substantially of the same diameter as the grooves 49 and 50.
When the receptacle 43 is inserted in the counterbore 37, the
receptacle is rotated until the grooves in the receptacle
oppose the grooves in the counterbore, thus forming two
cylindrical openings at these locations extending in a
direction axially of the combined cannula receptacle 43 and
valve body 23.
Referring now to FIGURES 3 and 4, a pair of rods
51 and 53, preferably of stainless steel, are inserted in
the cylindrical openings formed by the opposing grooves, the
suitable epo~y first havin~ been applied to the interface
between the cannula body wall 45 and the valve body counter-
bore 37. The relationship between the receptacle 43 and the
valve body 23 then becomes fixed. As will be seen hereinafter,
the cannula receptacle 43 is instrumental in causing the
rotation of the valve body 23 between positions of alignment
and nonalignment of the apertures and ports to selectively
establish fluid communication therethrough, and the stainless
steel rods form an interlock in the opposing grooves as a
safety feature in the event the epoxy should for any reason
let loose, The rods thus assure unison rotative movement
between the cannula receptacle and the valve body whenever
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rotative ~orce is applied to the cannula receptacle, which
occurs with the aid of a catheter as described hereinafter.
A cap 55 is applied over the open end of the housiny
19, the liner 21, and the valve body 23, including the
affixed cannula receptacle 43. The cap 55 is of a screw type,
and the outer surface of the housing 19 near its open end is
threaded to accommodate the cap 55. A shoulder 57 on the
interior of the cap 55 bears down upon the flange 47 of the
cannula receptacle to securely retain the valve body 23
affixed to the receptacle in a seated position within the
liner and housing.
As best seen in FIGURE 1, the cap 55 is provided with
a generally circular orifice 59 having a key slot 61 extending
outwardly from a point along its general circumference. The
key slot serves as an entrance to a circumferential slot 62
formed in the inner wall of the cap 55, the purpose of which
is described hereinafter. A generally longitudinal passage
63 (FIGURE 2) begins at the orifice 59 and extends through
the cannula receptacle 43 to the closed end of the valve body
23.
Referring now to FIGURE 3, this longitudinal passage
63 receives a catheter 65 inserted to establish a flow path
for the blood when blood passage is established by alignment
of the ports 29 and 31 with the apertures 25 and 27 respect-
ively in accordance with the invention. The catheter 65 istapered on its end outer surface to conform to the interior
taper of the longitudinal passage 63 in the interior closed
end portion of the valve body 23. To effect simultaneous
withdrawal and return of blood from the living body, the
catheter 65 is of dual-ccnduit design, having a pair of
side-by-side conduits 67 and 69. The conduit 67 is closed
at the tip of the catheter, and fluid communication to the
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port 31 of the valve body 23 is established through a side
port 71 of the catheter wall positioned to align with the
port 31 when the catheter tip is completely inserted. The
conduit 69, on the other hand, is open-ended and provides
im~ediate fluid communication with a cavity 73 at the closed
end of the valve body 23 between the tip of the catheter and
the inside end of the valve body. The port 29 is, of course,
in communication with the cavity 73, and a fluid flow is thus
established from the interior of the conduit 15 to the
conduit 69 when the port 29 is aligned with the aperture 25
in the wall of the conduit 15.
Although arrows in FIGURE 3 indicate a directional
flow from the interior of the conduit 15 outwardly through
the conduit 69 and return through the conduit 67 to the
interior of the conduit 17, it should be understood that
this is for the purpose of depicting a simultaneous outward
and return flow of a fluid in the blood access device 13,
rather than for stressing a particular direction of flow.
The direction of both arrows could be reversed to indicate
a reverse direction of flow in accordance with the invention.
The catheter 65 is inserted into the longitudinal
passage 63 when the valve is closed, i.e., when the ports 29
and 31 are in a nonaligned relation with the apertures 25 and
27 respectively. To establish a passage for blood in accord-
ance with the invention, the catheter 65 is used as an instru-
ment to rotate the valve body 23 to align the ports with the
apertures. After such rotation, the valve is open and a
passage for blood is established.
To effect such rotation of the valve body by the
catheter 65, the catheter tip is further provided with a
pair of flutes 75 and 77 in the outer walls of the catheter
tip that are located 180 from each other, and a pair of
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longitudinal guides 79 and 80 (FIGURE 8) are located on the
back sides respectively of grooves 49 and 50 in the bod~ wall
45 of the cannula receptacle ~3. Accordlnyly, before the
catheter 65 can be inserted in the longitudinal passage 63,
the catheter must be rotated to align the flutes 75 and 77
with, and thus engage, the longitudinal guides 79 and 80
upon insertion of the catheter. Because the cannula receptacle
which the catheter thus engages is afLixed to the valve body
23, the valve body will be rotated upon rotation of the
catheter.
It would be completely undesirable for the catheter
65 to be removable when the valve is open and blood is flow-
ing. To avoid such a circumstance, a lug 81 e~tending at
right angles outwardly from the catheter wall is provided on
the catheter 65. As best seen in FIGURE 5, this lug is shaped
and sized to pass freely through the key slot 61 in the cap
55, when the valve is closed and the catheter is aligned for
insertion therein. The circumferential slot 62 provided in
the cap 55 receives the lug 81 and retains the catheter 65
in its seated position when the catheter is rotated to open
the valve. Thus, it may be seen in FIGURE 1 that the insertion
of the catheter 65 will stop after the lug 81 has entered and
passed through the key slot 61. Rotative movement to open
the valve thereafter occurs.
Referring once again to FIGURE 5, the cap 55 is
also provided with indicia to indicate the particular relative
rotative positions of the catheter 65 and the cap 55. A small
protrusion 85 in the form of a pointer is provided on the
catheter at a position 180 from the lug 81 and a mark with
the word "open" or the like is provided on the top surface
of the cap at a point to which the catheter 65 must be
rotated to effect the opening of the valve. Because the
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1:12~302
luy 81 at that point is secure in the slot 62, th~ catheter
can only be removed when the valve is closed by a rotation
of the catheter adequate to align the lug ~1 with the key
slot 61 for removal. Thus, to interrupt the blood passage,
the catheter 65 is rotated at least one-quarter of a -turn,
and at this point the ports and the apertures are not aligned.
Because of the close-fitting, seated relation of the valve
body 23 with the liner 21, there is a liquid and hacterial
seal established around the sharp edges 33 and 35 respectively
of the apertures 25 and 27, as is more completely described
hereinafter. The bacterial seal is a barrier to the invasion
of bacteria in the blood stream through the interfaces of the
moving parts of the blood access device 13.
Returning to FIGURE 1, around the perimeter of the
housing 19 is a stabilizing button 87 that has the appearance
in a sectional view (e.g., FIGURES 2 and 3) of a collar
button, a smaller flange 89 being at one end of the button
and a larger flange 91 being at the other end. In practice,
this button is applied over the housing such that the smaller
flange 89 will be disposed at the ap~roximate level of the
skin surface. These flanges on the button project outwardly
from the housing, and the larger flange 91 carries a plurality
of holes 93. ~hen the blood access device 13 is implanted in
a human body, body tissue will grow in and around the holes 93
and stabilize the position of the blood access device in the
body. The position of the button 87 may be movable axially
of the housing to control the extent the housing extends
beyond the surface of the skin, or the position of the button
may be fixed if uniformity of housing height above the flange
is found to be desirable. Further, it may be desirable to
also include an epithelium stopping means in the form of
another collar (not shown) between the flanges 89 and ~1, as
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described in ~nited States Patent No. 3,783,86~, issued
Januaxy 8, 197~, to inhibit the progressive growth o~
epithelium tissue down and around the housin~ 19.
It should be recognized that although the blood
access device 13 is useful in a living human body, it may
also have veterinary or scientific applications in livin~
animals, domestic or wild. It should also be understood
that the device of the invention may be inserted in any part
of a circulatory system as needed.
The device 13 is inserted in the living body by any
suitable surgical procedure. Generally, a longitudinal
incision is made through the skin at the desired location for
insertion in the blood vessel, and an incision is made in the
blood vessel after monentarily stopping the flow of blood
therethrough. Sutures (not shown) are then used to sew up
the blood vessel after the ends of the conduit 15 have been
inserted therein, and other sutures (not shown) are used to
sew up the skin around the housing 19 as illustrated. In
this connection, it is noted that the length of the housing
19 above the point of association with the condui-t 15 is
suf ficient to extend from the blood vessel in which the
conduit 15 is inserted to a point outside the living body,
i.e., outside the skin layer. Alternatively, the blood
vessel may be severed and the severed ends slipped over the
protruding ends of the conduit 15 without engaging the device
housing 19. The conduit 17 is then connected to the circula-
tory system by a graft at points upstream or downstream from
the incision and insertion of the conduit 15. Although for
purposes of description, the conduit 15 has been described
and illustrated as being inserted in the blood vessel, and
the conduit 17 as being connected to the graft, it is in
accordance with the invention that the conduit 17 could be
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l~LZ3302
inserted in the blood vessel and conduit 15 connected to
the gra~t, at the option of the surgeon.
An alternative construction of a dual-conduit catheter
is illustrated in FIGURE 11 by ca-theter 65a. Here the two
conduits are arranged concentrically rather than side-by-side
while the external construction is fluted and tapered the same
as the catheter 65 described previously. Thus, a conduit 95
is open-ended and forms the center conduit, and a conduit 97
is concentric with the conduit 95, but is closed-ended and has
as its opening a port 99 in its side wall. Referring briefly
again to FIGURE 3, it will be seen that this alternative
catheter 65a may be inserted in the same manner as the
catheter 65, it being understood that the alternative catheter
65a will have a pair of 1utes and a lug the same as the flutes
75 and 77 and lug 81 of the catheter 65. It should be under-
stood also that when the alternative catheter 65a is inserted
in the blood access device 13, the port 99 will align with
the port 31 in the valve body 23, and so the conduit 97 will
have fluid communication with the interior of the conduit 17,
whereas the conduit 95 will have fluid communication through
the cavity 73 to the interior of the conduit 15.
~ s mentioned previously, because the blood access
device 13 is inserted within a living body, it is important
that the material of the device be biocompatible (biologically
compatible) with the blood and living tissues which surround
it. Furthermore, the device, once inserted, should not
prevent healing, irritate tissues, or stimulate a strong or
prolonged rejection response by the living body, and the
material of the device should be physiologically inert over
long periods of time in addition to being mechanically strong
and reliable.
In accordance with the invention, a coating of carbon
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is utilized on all blood contacting surfaces and on the
housing/skin interface. This carbon coating may be pyrolytic
carbon, vapor-deposited carbon or vitreous carbon, and -these
kinds of coatings may be utilized on diEferent parts of the
blood access device 13. Pyrolytic carbon, vitreous (glassy)
carbon, and vapor-deposited carbon are compatible with the
surrounding -tissues over prolonged time periods when inserted
through the skin layer of a living body. Preferably, pyrolytic
carbon and/or vapor-deposited carbon are used. These coatings
do not tend to irritate the surrounding skin tissues and they
promote the establishment of a barrier to external pathogens.
In general, the preferred construction of the device
13 includes a metallic housing, such as titanium, stainless
steel or a chromium-cobalt alloy such as VITALLIUM. Preerably,
the housing is constructed of titanium. The conduits 15 and 17
are constructed of pyrolytic carbon and may be formed in any
suitable manner, such as deposition of a built-up coating on
a mandrel, after which the mandrel is removed, leaving the
tubelike structures. Both -the liner 21 and the valve body 23
are constructed by pre-shaping a suitable substrate, such as
a ~raphite core, in the general form of a cylinder and having
one end taper gradually to a reduced diameter. A coating of the
pyrolytic carbon is then made thereon, and the graphite is
removed, as by drilling, leaving a pyrolytic carbon shell.
The interfacial surfaces, particularly of the tapered portions,
are lapped and polished to enhance a close-fit relation with
adjacent parts. The ports are then made in a suitable manner,
as by drilling. The button 87 also is constructed on a suitable
substrate or graphite core which is preshaped to the desired
form, which includes both the smaller flange 89 and the larger
flange 91, the holes 93 then being formed in the flange 91,
such as by drilling, and a pyrolytic carbon coating being
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applied to the core, including the inner sur~aces o~ the
holes 93. Preferably, on this button the carbon coating has
a rough finish. The core materials and the process of apply~
ing the pyrolytic carbon coatings are described in detail
hereinafter.
The cannula receptacle 43 preferably is made from
stainless steel and formed in a suitable manner, such as by
a stamping and drawing operation. The cap 55 is machined
in a suitable manner, preferably from stainless steel, as
are also the interlocking rods 51 and 53 (FIGURE 4).
One such blood access device 13 has been constructed
in which the overall length of the housing 19 is approximately
0.8 inch and its outer diameter is approximately 0.35 inch.
The location of the condui~ 17 with respect to the open end
of the housing 19 is such that the axis of the conduit 17 is
approximately 0.5 inch from the open end. The overall diameter
of the larger flange 91 is approximately 0.75 inch. The holes
93 in the flange 91 are 0.1 inch in diameter. The pyrolytic
carbon wall thickness of both the liner 21 and the valve body
23 is approximately 0.03 inch. The diameter of the longitudinal
passa~e 63 inside the valve body 23 is 0.19 inch, and from such
diameter the walls taper inwardly at an angle of 5~ 45'. The
interlocking stainless steel rods 51 and 53 are 0.01 inch in
diameter and are approximately 0.2 inch long.
These dimensions are provided by way of giving an
example of construction, but there is no intention of requiring
the construction to be limited to any of these dimensions.
As seen in FIGURES 2 and 3, when the conduits 15 and
17 are inserted and join~d to the housing 19, the side walls of
the conduits intersect the liner 21 and valve body 23. The
portion of the conduit wall that would intersect the valve body
23 is formed in a suitable manner, as by grinding, to conform
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to the general shape of the circular outer surface of the
valve body 23 to form a seat for the valve. The interfacial
surfaces are then lapped and polished to form a good seal
therebetween in this snug or close-fitting relation. In this
connection, a very important step in making the blood access
device 13 is the lapping of the portion of the external surface
of the conduits 15 and 17 that are in contact with the valve
body 23 to conform these portions to the circular surface of
the valve body so as to produce the sharp edges 33 and 35
(FIGURES 2 and 3) as well as seats for the valve. Such a
sharp edge does not permit the accumulation and coagulation
of blood around the aperture. Thus, after having once
established fluid communication between a blood vessel and
the catheter 65 or 65a and then closing the valve body by
rotation thereof, the blood flow will be cleanly interrupted
with no places for accumulation or coagulation of the blood
in the conduits 15 and 17. After the valve is closed, any
residual blood in the valve body 23 may be flushed out by
using a suitable cleansing solution. Thereafter, a suitable
plug (not shown) may be applied over the end of the cap 55 to
keep the interior clean until next use.
The pyrolytic carbon may be deposited upon the
mandrels in the instance of the conduits 15 and 17 and upon
the core materials for the other parts in the manner described
in United States Patent No. 3,783,868 and United States Patent
No. 3,298,921. An example of a coating method that may be
employed is that of supporting the formed substrate on a
rotating or stationary mandrel within a large fluidized bed,
as discussed in the aforementioned patents, or coating on
freely moving rods in a fluid bed.
Pyrolytic carbon is, by definition, deposited by
the pyrolysis of a carbon-containing substance. Accordingly,
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the core material on which the pyrolytic carbon is deposited
will be subject to -the fairly high temperatures necessary
for pyrolysis. Generally, hydrocarbons are employed as the
carbon-containing substance to be pyrolyzed, and temperatures
of at least about 1000C are used. Some examples of deposition
of pyrolytic carbon are set forth in the aforementioned U.S.
Patent No. 3,298,921. Processes illustrated and described
in this patent employ methane as the source of carbon and
utilize temperatures generally in the range of about 1200C
to 2300C. Although it is possible to deposit pyrolytic
carbon having the desired properties with regard to this
invention at somewhat lower temperatures by using other
hydrocarbons, for example, propane or butane, it is generally
considered that the core material should remain substantially
stable at temperatures of at least about 1000C and preferably
at even higher temperatures. Pyrolytic carbons deposited at
temperatures below about 1500C are particularly suited for
use in the blood access device 13, because such pyrolytic
carbons have exceptional tissue compatibility and mechanical
reliability.
Examples of core materials which have the afore-
mentioned stability at high temperatures include artificial
graphite, boron carbide, silicon carbide, refractory metals
(and alloys), such as tantalum, titanium, molybdenum, tungsten,
and various ceramics, such as mullite. A preferred substrate
material is polycrystalline graphite. An example of such a
graphite is the polycrystalline graphite sold under the
trademark POCO.
Vapor-deposited carbon coatings may be applied by
the process described in United States Patent 3,952,334
"Biocompatible Carbon Prosthetic Devices", issued April 27,
1976. As generally described therein, a substrate is placed
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in an evaporative coater and a vacuum is established. A
crucible within the coater, filled with a commercial grade
of artificial graphite, is heated by electron beam bombardment.
Coating is carried out until the desirecl thickness of carbon
is deposited and the substrate is then removed. This process
results in an exterior carbon layer that is smooth and uniform.
The features that provide a system for Joining
catheters to implanted blood access devices in accordance
with the invention are next described in connection with a
uni-directional blood access device. Such uni-directional
access device, i.e., a device in which the fluid flows in
only one direction at a time, is shown in FIGURES 11 and 14
as device 101. Reference numbers with subscript "a" are used
to indicate parts in this device 101 that are like corres-
ponding parts of the device 13 described earlier. A conduit
15a is a round tubular structure, open-ended, and intended
for insertion in a blood vessel in the same manner as either
the conduits 15 or 17 of the device 13 (FIGURE 1). This
conduit 15a adjoins a housing 103 along the side wall o~ the
housing. The interiors of the two parts are separated by a
wall 105 common to both. In the common wall is an aperture 107
that provides fluid communication between the two interiors
and is defined by a perimeter formed by a sharp edge 109 of
the common wall.
In the housing 103 is a valve body 111. At least
the interior surface of the housing 103 is tapered as indicated
and at least the outer surface of the valve body 111 is tapered
in a conforming manner to the housing interior. These con-
forming tapered surfaces afford a very close interfitting
relationship. Nonetheless, the valve body 111 is movable
within the housing. Specifically, in this illustrated device
101, the valve body and the housing are coaxially related,
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~Z33C~
and the valve body is rotatable about the axis in the
housing.
Facilitating this rotation is a cannula rece~ptacle
43a inserted in an a-ffixed relation in a counterbore 37a
prcvided in the open end of the valve body 111. Similar to
those shown in FIGURE 9, grooves 39a and 41a are provided
in the inner surface of the counterbore 37a. These grooves
also are coterminous with the counterbore and extend in a
direction axially of the valve body.
The cannula receptacle 43a also is provided with
a body 45a and a top flange 47a. The body 45a has an outside
diameter that forms a snug fit when the cannula receptacle
is inserted in the counterbore. A suitable epoxy or other
cement is used to affix the cannula receptacle 43a to the
valve body 111 after the desired rotative position of the
receptacle with respect to the valve body has been established.
This desired position involves the pair of grooves 49a and 50a
(corresponding to grooves 49 and 50 in FIGURE 7) in the outer
surface of the body wall 45a extending in a direction axially
of the cannula receptacle. These grooves 49a and 50a are 180
apart in the outer surface of the body wall and are semicircular
in cross section as are the grooves 39a and 41a, also 180
apart, in the inner surface of the counterbore 37a of the
valve body 111. When the cannula receptacle 43a is inserted
in the counterbore 37a, the receptacle is rotated until the
grooves in the receptacle oppose the grooves in the counterbore,
thus forming two cylindrical openings at these locations
extending in a direction axially of the combined cannula
receptacle 43a and valve body 111 in a manner similar to that
shown in FIGURE 4. A pair of rods 51a and 53a, preferably
of stainless steel, are inserted one for one in the cylindrical
openings formed by the opposing grooves, a suitable epoxy having
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l~Z33Q;~
first been applied to the interface between the cannula body
wall 45a and the valve body counterbore 37a. The rela-tionship
between the receptacle 43a and the valve body 111 then becomes
fixed. The stainless steel rods form an interlock in -the
opposing grooves as a safety feature in the event the epoxy
should for any reason let loose. The rods thus assure unison
rotative movement between the cannula receptacle and the valve
body whenever rotative force is applied to the cannula
receptacle, which occurs with the aid of a catheter described
hereinafter.
The valve body 111 is generally in the form of a
pyrolytic carbon cylinder having a lower closed end and a
longitudinal passage 113 parallel to the common axis and a
transverse passage 115 at an angle thereto terminating in a
port 117. The longitudinal passage 113 is located coaxially
of the housing 103. The -transverse passage llS is located
so as to align the port 117 with the aperture 107 in a given
axially rotative position of the valve body 111 to establish
fluid communication between the conduit l5a and the interior
of the valve 111 in the housin~ 103. The longitudinal passage
113 receives a catheter tip 119 in completing a flow path for
the blood. Blood flow is established by aligning the port
and the aperture in accordance with the invention.
The catheter is inserted in the longitudinal passage
113 when the valve is closed, i.e., the port 117 is in a
non-aligned relation with the aperture 107. To establish a
passage for blood in accordance with the invention, the
catheter tip 119 is used as an instrument to rotate the valve
body 111 to align the port with the aperture. After such
rotation, the valve is open and a passage for blood is
established.
To effect such rotation of the valve body by the
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catheter tip 119, the catheter tip is provided with a pair
of flutes 75a and 77a in its outer walls. These flutes are
located 180 from each other, and a pair of longitud:inal
guides 79a and 80a (similar to 79 and 80 in FIGURE 7) are
located on the back sides respectively of the grooves 49a and
50a. Accordingly, before the catheter tip 119 can be
inserted in t~e longitudinal passage 113, the catheter must
be rotated to align the flutes 75a and 77a with, and thus
engage, the longitudinal guides 79a and 80a upon insertion
of the catheter. Because the cannula receptacle which the
catheter thus engages is affixed to the valve body 111, the
valve body will be rotated upon rotation of the catheter.
As mentioned in connection with the description
of the device 13 of FIGURE 1, it would be completely undesir-
able for the catheter tip 119 to be removable when the valveis open and blood is flowing. To avoid such a circumstance,
a lug 81a extending at right angles outwardly from the
catheter tip wall is provided on the catheter tip 119. As
seen in FIGURES 12 and 13, this lug is semicircular in shape
when viewing from the end and flat when viewing from the
side.
It will be noted that the lug 81a is circumferentially
displaced 90 from the flutes in the illustrated catheter tip
119 of FIGURE 12, whereas the lug 81 is aligned with one of the
flutes as illustrated in the device of FIGURE 3. The circum-
ferential position of the lug will depend on the interrelation-
ship between the valve body, cannula receptacle, catheter tip
and cap. It is of importance that this interrelationship
establish the conditions in which the catheter can be inserted
and removed only when the valve is closed and the catheter
is locked in the inserted position when the valve is open.
The circumferential position of the lug, then, must be in
~:~L233~2
conformity with the relationship of the other ports that
establish these conditions.
A cap 55a is applied over the open end of the housing
103 and the valve body 111, including the affixed cannula
receptacle 43a. The cap 55a is of a screw type, and the
outer surface of the housing 103 near its open end is threaded
to accommodate this cap 55a. A shoulder 57a on the interior
of the cap 55a bears down upon the flange 47a of the cannula
receptacle to securely retain the valve body 111 affixed to
the receptacle in a rotatively seated position within the
housing.
As best seen in FIGURE 11, the cap 55a is provided
with a generally circular orifice 59a having a key slot 61a
extending outwardly from a point along its general circumfer-
ence. The key slot serves as an entrance to a circumferential
slot 62a formed in the inner wall of the cap 55a. The circum-
ferential slot 62a receives the lug 81a and retains the
catheter tip 119 in its seated position after the catheter
is rotated to open the valve. Thus, it may be seen in
FIGURE 11 that the insertion of the catheter tip 119 will stop
a~ter the lug 81a has entered and passed through the key slot
61a. Rotative movement to open the valve thereafter occurs.
The interlocking relation thus established between these parts
prevents an inadvertent removal of the catheter 119 when
the valve is open and blood is flowing. When the valve is
open, fluid may flow in either direction, one direction at
a time, in the established passage as circumstances direct.
The cap 55a may also be provided wi~h indicia to
indicate the particular relative rotative position of the
catheter 119 and the cap 55a similarly as shown in FIGURE 5.
Thus, a small protrusion in the form of a pointer may be
provided on the catheter at a position 180 from the lug 81a,
~L~ILZ3302
and a mark with the word "open" or the like may be provided
also on the top surface of the cap at a point to which the
catheter 119 must be rotated to effect the opening of the
valve. Because the lug 81a at that point is secure in the
slct 62a, the catheter can only be removed when the valve is
closed by a rotation of the catheter adequate to align the
lug 81a with the key slot 61a for removal. To interrupt the
blood passage, the catheter 119 is rotated at least one-quarter
of a turn, as indicated, or even a full one-half turn (not
shown) to assure that the port and aperture are not aligned.
When the aperture and the port are not aligned, i.e.,
the valve is closed, a portion of the outer surface of the
tapered side wall of the valve body 111 completely covers the
aperture 107 and establishes a liquid and bacterial seal
therearound. To facilitate this seal, the valve body extends
below the aperture to provide additional surface in close-
fitting relation with the interior of the housing 103. The
narrow end of the valve body does not bottom on the inside
of the housing, and there is clearance to assure adequate
seatin~ oE the valve body within the housing along the tapered
inter~ace to orm the li~uid and bacterial seal. Some slight
differences in diameters of the respective parts can be
tolerated with this tapered structure. For hygienic purposes,
the interior of the valve should be flushed out with a suitable
cleansing solution on a regular basis.
A stabilizing flange 121 having holes 123 may be
provided around the perimeter of the housing 103 in a manner
similar to that described in connection with the button 87 on
the device 13 (FIGURE 1). The body tissue grows in and around
the holes 123 to stabilize the position of the device 101 in
its implanted condition. This flange may be affixed on the
outside of the housing in a desired axial position by a
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~L~Z33~)2
suitable epoxy or cement.
In general, the device 101 is constructed in a
manner similar to that already described in connection wi-th
the device 13, i.e./ the housing machined from a metal,
preferably titanium, and the conduit 15a being pyrolytic
carbon and prepared on a mandrel. In this instance, the
valve body 111, however, may be prepared on a graphite core
with a pyrolytic carbon coating applied on the surfaces of
the core. The graphite is then removed, as by drilling, leaving
a pyrolytic carbon shell as the valve body~ The interfacial
surfaces of the tapered portions are lapped and polished to
enhance the close-fit relation with the housing. The housing
103 may also be coated on its exterior surface with a layer
125 of pyrolytic carbon.
An important step in constructing this device 101,
is the lapping of the outer surface of the portion of the
conduit wall 15a adjacent the lower end of the valve body 111
in the housing 103 to provide the sharp edge 109 that defines
the aperture 107. As described previously in connection with
the device 13, such a sharp edge does not allow the accumula-
tion and coagulation of blood around the aperture. Thus, after
having once established fluid communication between a blood
vessel and the catheter 119 and then closing the valve by
rotating the valve body 111, the blood flow will be cleaning
interrupted with no places for accumulation or coagulation of
the blood in the conduit 15a. When the valve is closed and
the catheter removed, any residual blood in the longitudinal
passage 113 and the transverse passage 115 is flushed out by
using a suitable cleansing solution. Thereafter, a suitable
plug ~not shown) may be inserted in the upper end of the
longitudinal passage to keep the interior clean until next
use.
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330Z
Summarizing, there has been shown a ca-theter inter-
lock system which includes a blood access device having at
least one conduit adapted for insertion in the circulatory
system of a living body. A housing of the device has an
open end, and the interior of the housing is in fluid communi-
cation with the conduit. A coaxially rotatable valve body is
provided in the housing, and the valve body has an axial bore
in its outer end. A cannula receptacle is inserted in an
affixed relation in the axial bore, and a flange is provided
on the cannula receptacle that overlies the outer end of the
valve body. A catheter tip is adapted for insertion in and
engagement with the cannula receptacle. A lug on the outer
surface of the catheter tip extends outwardly at right angles
to the axis o~ the catheter, and a cap is provided over the
open end of the housing, valve body and cannula receptacle.
The cap is of the screw type and has a shoulder for bearing
against the flange of the cannula receptacle to provide
compression to retain the valve body in a rotatively seated
condition in the housing. The cap also is provided with a
generally circular orifice and a key slot adjacent the circum-
ference of the orifice. The cap also is provided with a cir-
cumferential slot in the inner wall thereof adjoining the
key slot. The key slot serves as a passageway for the lug
to enter the circumferential slot. The lug secures the
position of the catheter after insertion thereof in the
cannula receptacle through the cap and after rotation of
the catheter to engage the lug in the circumferential slot.
This prevents an inadvertent removal of the catheter when
the valve is open.
While the invention has been described in connection
with a preferred embodiment~ alternatives, modifications, and
variations may be apparent to those skilled in the art in
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~.~Z33(1;2
view of the foregoing description. ~ccordingly, it is
intended to embrace all such alternatives, modifications,
and variations as fall within the spirit and scope of the
appended claims.
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