U.S. patent application number 11/338597 was filed with the patent office on 2007-01-18 for valve port and method for vascular access.
This patent application is currently assigned to VASCA, Inc.. Invention is credited to James M. Brugger, Jeffrey H. Burbank.
Application Number | 20070016162 11/338597 |
Document ID | / |
Family ID | 36568851 |
Filed Date | 2007-01-18 |
United States Patent
Application |
20070016162 |
Kind Code |
A1 |
Burbank; Jeffrey H. ; et
al. |
January 18, 2007 |
Valve port and method for vascular access
Abstract
Valved ports for accessing blood vessels and other body lumens
include a lock mechanism which locks the valve fully open when a
needle or other access tube is placed into the port. The lock
mechanism includes a latch typically comprising one or more
laterally deflectable elements, such as a pair of opposed balls.
The deflected elements are pushed outwardly by the needle to engage
a recess in the port which locks the valve open until the needle is
removed.
Inventors: |
Burbank; Jeffrey H.;
(Boxford, MA) ; Brugger; James M.; (Newburyport,
MA) |
Correspondence
Address: |
TOWNSEND AND TOWNSEND AND CREW, LLP
TWO EMBARCADERO CENTER
EIGHTH FLOOR
SAN FRANCISCO
CA
94111-3834
US
|
Assignee: |
VASCA, Inc.
Tewksbury
MA
|
Family ID: |
36568851 |
Appl. No.: |
11/338597 |
Filed: |
January 23, 2006 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
09431008 |
Nov 1, 1999 |
7056316 |
|
|
11338597 |
Jan 23, 2006 |
|
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|
08942990 |
Oct 2, 1997 |
6007516 |
|
|
09431008 |
Nov 1, 1999 |
|
|
|
60036124 |
Jan 21, 1997 |
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Current U.S.
Class: |
604/500 ;
604/167.06; 604/288.03 |
Current CPC
Class: |
A61M 39/0693 20130101;
A61M 39/0208 20130101; A61M 2039/009 20130101; A61M 39/26
20130101 |
Class at
Publication: |
604/500 ;
604/288.03; 604/167.06 |
International
Class: |
A61M 31/00 20060101
A61M031/00 |
Claims
1. A method for percutaneously accessing a body lumen, said method
comprising: maintaining a conduit between an implanted access port
and the body lumen, said conduit being opened and closed by a valve
within the port; and percutaneously inserting an access tube into
an implanted access port, wherein inserting the access tube opens
the valve and displaces at least one space-filling element into a
receptacle to lock the valve open until the access tube is
removed.
2. A method as in claim 1, wherein the space filling element is a
ball.
3. A method as in claim 1, wherein inserting the access tube
laterally displaces at least the opposed balls into the receptacle
so that the tube holds the balls in place until the tube is
removed.
4. A method as in claim 1, wherein the bore comprises a tapered
bore which seals against the access tube as said tube is inserted
therein.
5. An implantable port comprising: a base having a passage for
receiving an access tube; a valve assembly in the base, said valve
assembly having a bore which receives the access tube and wherein
the valve assembly opens in response to movement of the access
tube; and a valve lock having a latch which shifts position to lock
the valve assembly open in response to movement of the access tube
prior to seating of the access tube in the bore of the valve
assembly.
6. An implantable port as in claim 5, wherein the valve assembly
opens in response to motion of a needle.
7. An implantable port as in claim 5, wherein the latch comprises
at least one space-filling element which is displaced from the
passage into a receptacle adjacent to the passage as the access
tube is inserted into the passage, wherein the space-filling
element remains in the receptacle to lock the valve open so long as
the access tube remains in the bore.
8. An implantable port as in claim 7, wherein the valve assembly
comprises a plunger and wherein a pair of space-filling elements is
displaced both downwardly to lower the plunger to open the valve,
and outwardly into the receptacle, to lock the plunger open.
9. An implantable port as in claim 7, wherein the latch comprises a
pair of balls which are displaced laterally.
10. An implantable port as in claim 5, wherein the valve assembly
comprises a valve selected from the group consisting of pinch
valves sliding valves, slit valves, duckbill valves and leaflet
valves.
11. An implantable port as in claim 5, wherein the bore comprises a
tapered bore which seals against the access tube as said tube is
inserted therein.
Description
CROSS-REFERENCES TO RELATED APPLICATIONS
[0001] The present application is a divisional of and claims the
benefit of priority from application Ser. No. 09/431,008, filed
Nov. 1, 1999, which is a continuation-in-part of application Ser.
No. 08/942,990, filed Oct. 2, 1997 (now U.S. Pat. No. 6,007,516,
issued Dec. 28, 1999), which claimed the benefit of provisional
Application No. 60/036,124, filed on Jan. 21, 1997, the full
disclosures of which are incorporated herein by reference.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates generally to the design and
use of medical devices, and more particularly to the design and use
of an implantable port for establishing temporary access to a
patient's vascular system for hemodialysis and other extracorporeal
blood treatments.
[0004] Access to a patient's vascular system can be established by
a variety of temporary and permanently implanted devices. Most
simply, temporary access can be provided by the direct percutaneous
introduction of a needle through the patient's skin and into a
blood vessel. While such a direct approach is relatively simple and
suitable for applications, such as intravenous feeding, intravenous
drug delivery, and other applications which are limited in time,
they are not suitable for hemodialysis and other extracorporeal
procedures that must be repeated periodically, often for the
lifetime of the patient.
[0005] For hemodialysis and other extracorporeal treatment
regimens, a variety of implantable ports have been proposed over
the years. Typically, the port includes a chamber and an access
region, such as a septum, where the chamber is attached to an
implanted catheter which in turn is secured to a blood vessel. In
the case of veins, the catheter is typically indwelling and in the
case of arteries, the catheter may be attached by conventional
anastomosis.
[0006] Of particular interest to the present invention, implantable
ports typically include a needle-penetrable septum which permits
the percutaneous penetration of a needle into the internal chamber.
The chamber, in turn, is connected to one end of the catheter, and
the other end of the catheter is indwelling in the blood vessel.
While workable, such designs suffer from a number of problems.
Repeated penetration of the septum often leads to degradation over
time, presenting a substantial risk of small particulates entering
the blood stream and/or need to periodically replace the port.
Second, the passage of blood through the chamber or plenum will
often encounter regions of turbulence or low flow, either of which
can degrade the quality of blood over time.
[0007] To overcome these problems, some implantable ports have an
internal valve structure which isolates the interior of the port
from the lumen of the implanted catheter when the port is not in
use. Such valved ports, however, have their own shortcomings. For
example, self-penetrating needles often cannot be used since they
will be damaged by and/or cause damage to the port. In such
instances, it is frequently necessary to use a catheter combined
with a removable stylet, which is both more costly and more
inconvenient than use of a simple needle. Moreover, many valved
ports have no means or mechanism to assure that the valve is fully
opened, particularly when insertion of the access needle opens the
valve. In such instances, partial insertion of the needle can
result in partial opening of the valve.
[0008] Needle-actuated valved ports are described in a number of
the patents listed below. For example, the ports described in U.S.
Pat. Nos. 5,741,228 and 5,702,363, show a port having a duckbill
valve which is opened by an elastomeric plug which is elongated by
insertion of a needle. So long as the needle is fully inserted, the
valve will be fully opened. It would be possible, however, to only
partially insert the needle, resulting in only partial opening of
the duckbill valve. Such partial opening could significantly
degrade and alter the valve performance.
[0009] For these reasons, it would be desirable to provide improved
valved implantable access ports for percutaneously accessing a
patient's blood vessels, including both arteries and veins. The
access ports will comprise a valve structure for isolating the port
from an associated implanted catheter when the port is not in use.
The valve will preferably provide little or no structure within the
blood flow lumen of the access port and will even more preferably
not require passage of a needle or other access tube through the
seating portion of a valve in order to open the valve. Furthermore,
the port structure including the valve elements therein will have a
substantially uniform cross-sectional area and will present no
significant constrictions or enlargements to disturb fluid flow
therethrough. Preferably, the port designs will permit percutaneous
access using a conventional needle, such as a fistula needle,
without damage to either the port or the needle. Still more
preferably, the ports will include means for locking the valve
structures open in response to insertion of the needle or other
access device. Ports and valves according to the present invention
will meet at least some of these objectives.
[0010] 2. Description of the Background Art
[0011] U.S. Pat. No. 5,562,617 and WO 95/19200, assigned to the
assignee of the present application, describe implantable vascular
access systems comprising an access port having an internal slit or
duckbill valve for preventing back flow into the port. Vascular
access ports having various valves for isolating the port from the
vascular system in the absence of external percutaneous connection
to the port are described in the following U.S. Pat. Nos.
5,954,691; 5,741,228; 5,702,363; 5,527,278; 5,527,277; 5,520,643;
5,503,630; 5,476,451; 5,417,656; 5,350,360; 5,281,199; 5,263,930;
5,226,879; 5,180,365; 5,057,084; and 5,053,013. Other patents and
published applications which show implantable ports having valve
structures opened by insertion of a needle include U.S. Pat. Nos.
4,569,675; 4,534,759; 4,181,132; 3,998,222; and WO 96/31246. U.S.
Pat. No. 5,637,088 describes a septum-type implantable port which
employs a dual needle to help prevent dislodgment.
SUMMARY OF THE INVENTION
[0012] The present invention provides devices and methods for
percutaneously accessing a body lumen through an implanted access
port. More particularly, the present invention provides methods and
devices for locking open a valve assembly within an access port by
the act of inserting the access tube. Insertion may involve simply
advancing the access tube in the forward direction, or it may
involve additional or alternative movements such as rotation.
Reversal of the needle movement and/or removal of the access tube
will in turn release the lock and close the valve assembly. The
present invention provides a "positive" locking action and reduces
any variability in access, such as a "half-opened" valve, and
reduces the risk of blood loss due to valve closure during fluid
transfers.
[0013] The implantable access ports for use with the present
invention are preferably capable of high volume withdrawal and/or
return of blood or other fluids, particularly for patients
undergoing an extracorporeal blood therapy, such as hemodialysis,
hemofiltration, hemodiafiltration, apheresis, or the like. The
vascular access ports allow for high volumetric rates of blood or
other fluid flow therethrough, typically allowing for rates above
250 ml/min, usually above 300 ml/min, preferably at least 400
ml/min, and often 500 ml/min or higher, using a single needle or
other access device. Such high volumetric flow rates are quite
advantageous in reducing the time required for performing the
extracorporeal blood treatment, particularly for otherwise lengthy
treatments which require large total volumes of treated blood, such
as hemofiltration. To ensure high flow rates and minimum time
requirements, it is useful to know that the valve is completely
open, allowing full access to the body lumen through the conduit
while the access tube is in place. Likewise, it is beneficial to
know that the valve is completely closed when the access tube is
removed, either by careful disengagement or by accidental pull-out,
since such high flow rates will cause a significant amount of fluid
to be lost if the valve is unknowingly left open.
[0014] According to a first aspect of the method of the present
invention, a body lumen in the patient may be accessed by
percutaneously inserting an access tube into an implanted access
port. The access tube may be percutaneously inserted into the
access port so that the access tube engages a valve lock having a
latch which opens a valve structure within the port or the conduit.
Alternatively, the latch may open the valve structure as a result
of rotational or other movement of the access tube during or
subsequent to insertion. The valve structure is located remotely
from that portion of the access port into which the access tube has
been inserted and may be present in the conduit itself or in a
separate assembly within the port. The latch may be mechanical or
hydraulic, usually being mechanically coupled to a spring-loaded
valve assembly or a spring-loaded plunger assembly which
mechanically opens a valve. Alternatively, a hydraulic latch could
be provided where a pushing force on a plunger assembly is
hydraulically actuated or a valve opened by insertion of the access
tube.
[0015] In a more particular aspect of the present invention, an
implantable port comprises a base having a passage for receiving an
access tube. A valve assembly is disposed in the base and includes
a bore which is aligned with the passage in the base and which also
receives the access tube. The valve assembly is locked by action of
a latch which shifts position to lock the valve assembly open in
response to movement of the access tube. The latch is disposed
between the passage in the base and the bore in the valve. The
latch typically comprises at least one space-filling element. One
or a number of these elements are displaced into one or more
receptacles adjacent to the passage by movement of the access tube
in the passage, wherein the presence of the space-filling elements,
typically opposed balls, in the receptacle locks the valve open.
When the valve is opened by action of a plunger, such as a plunger
protruding through a duckbill or miter valve, the balls or other
space-filling elements move downward and outward to depress the
plunger and lock the plunger open.
[0016] The space-filling elements of the latch typically comprise a
pair of balls, usually opposed stainless steel balls similar to
small ball bearings, disposed between the passage in the base and
the bore in the valve. In valve assemblies that open and close with
the action of a spring-loaded plunger, the balls are spring-biased
to close against one another between the passage and the bore in
the valve assembly. In one embodiment, the insertion of the access
tube through the passage forces the balls apart and the access tube
passes into the bore of the valve assembly. As the balls move apart
(outward), they also move downward into receptacles. This movement
is directed by interior walls sloping outward between the passage
and the bore. Such action depresses the plunger, which opens the
valve. While the access tube is inserted, the balls are held
against the tube and in the receptacles by the spring-loaded
plunger and the angled interior walls. Not only does this lock the
valve open, but the static friction of the balls against the tube
may help to hold the access tube in the passage. Interior walls
with an angle of 50 degrees or greater (relative to a lateral plane
through the port) have been found to provide higher frictional
forces for needle retention. Removal of the tube allows the balls
to move out of the receptacles in an upward direction, by action of
the spring-loaded plunger, and an inward motion directed by the
angled interior walls so that they are again in contact in the
passage. In alternative embodiments, insertion of the access tube
may be coupled with a rotational movement of the access tube. Such
rotational motion would force the balls apart and facilitate the
movement of the balls into the receptacles, thus opening the valve.
Reversal of such movement by the access tube and/or removal of the
access tube subsequently closes the valve.
[0017] In a second aspect of the method of the present invention,
percutaneous access to a patient's blood vessel is provided by
maintaining a conduit between an implanted access port and the
blood vessel. An access tube is percutaneously inserted into a tube
seat within the access port to establish a generally fluid tight
seal therein. When inserted, the access tube actuates a valve lock
to open a valve structure to permit flow through the conduit. The
valve structure will usually be internal to the port but, in some
cases, could be located outside of the port itself. Preferably, the
tube seat comprises a tapered bore within the access port which
frictionally engages the outside access tube as the tube is
inserted into the bore. More preferably, insertion of the access
tube into the tube seat depresses the tube seat relative to a base
of the access port in order to actuate the valve lock which opens
the conduit. The valve lock may take a variety of forms, including
latch motions as described above.
[0018] The tube seat will remain locked in its depressed condition
until the access tube is removed from the base. By forming the tube
seat from (or lining the tube seat with) a hard material,
preferably a material harder than the needle or other access device
which is to be used, the likelihood of damage to the valve can be
greatly reduced. Moreover, the tapered tube seat design is not
prone to damaging needles when they are inserted into the port.
Thus, the port of the present invention is particularly suited for
use with self-penetrating, sharpened needles, such as fistula
needles, unlike many ports of the prior art.
[0019] A further understanding of the nature and advantages of the
invention will become apparent by reference to the remaining
portions of the specifications and drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0020] FIG. 1 is a perspective view of an access port having a
flexible conduit extending therefrom constructed in accordance with
the principles of the present invention.
[0021] FIG. 2 is a side, cross-sectional view of the access port of
FIG. 1 shown with a closed internal clamp structure.
[0022] FIG. 2A is a partial cross-sectional view taken along line
2A-2A of FIG. 2.
[0023] FIG. 3 is a side, cross-sectional view of the access port of
FIG. 1 as shown with the internal clamp structure opened in
response to the insertion of an access needle.
[0024] FIG. 3A is a partial cross-sectional view taken along line
3A-3A of FIG. 3.
[0025] FIG. 3B is a detailed, cross-sectional view illustrating the
taper of a needle when inserted into the Port of FIG. 3.
[0026] FIGS. 4A and 4B illustrate an alternative pinch tube
connection design.
[0027] FIGS. 5A and 5B illustrate a slide valve embodiment of the
implantable port of the present invention.
[0028] FIGS. 6A and 6B illustrate an access port having a valve
lock mechanism which functions with a duckbill valve.
DESCRIPTION OF THE SPECIFIC EMBODIMENTS
[0029] The present invention provides methods and apparatus for
facilitating percutaneous access to a body lumen of a patient.
Exemplary body lumens, include blood vessels, the peritoneal
cavity, and the like. The methods are particularly useful for
accessing blood vessels, including both arterial blood vessels and
venous blood vessels. While the remaining description is directed
particularly at blood vessels, it will be appreciated that the
invention applies to all body lumens and cavities where selective
percutaneous access might be desired. For example, the ports can be
used for introduction and removal of dialysate in peritoneal
dialysis procedures. Access ports according to the present
invention are implanted subcutaneously so that a passage therein
lies a short distance beneath the surface of the patient's skin,
typically being within 3 mm to 20 mm of the skin's surface. An
access tube may then be percutaneously inserted into the passage in
the access port in order to provide communication with the blood
vessel or other body lumen via the access port. Such access can be
provided for a variety of purposes, usually involving withdrawal of
blood, the extracorporeal treatment of the withdrawn blood, and/or
the return of the treated blood to the patient. Such extracorporeal
blood treatment will most often be for hemodialysis, but can also
be for hemofiltration, hemodiafiltration, apheresis, and the like.
In addition to extracorporeal treatment, the access port of the
present invention can be used for perfusing drugs, fluids, and
other materials directly into a patient's circulation for a variety
of purposes.
[0030] The present invention relies on implantation of the access
port and connection of the port to the target blood vessel or other
body lumen via a conduit, which is regulated by a valve. The valve
is opened by movement of an access tube in the port, and closed by
reversal of the movement, such movement may involve simply
inserting the access tube or it may involve rotational motion or
the like. When motion is applied, the access tube will engage a
valve lock having a latch which shifts position to lock the valve
assembly open. Locking the valve open ensures both that the valve
is completely open and that the valve remains open to prevent
accidental closure. When the tube is removed, the latch will shift
back to its previous position and unlock and the valve, both
ensuring that the valve is completely closed and avoiding the
possibility of accidental leakage.
[0031] The access tube will usually be a needle which can be
directly pierced (percutaneously introduced) through the patient's
skin and into the implanted port. Thus, the needle will usually
have a sharpened tip in order to permit it to be self-introduced
through the skin. Of course, access tubes having blunt distal ends
could be used by first piercing the skin with a separate blade,
stylet, needle, or the like, and thereafter introducing the access
tube into the resulting incision or hole. The access tube could
also be introduced using an internal stylet which is subsequently
withdrawn, leaving the tube in place in the port. While the port of
the present invention can accept a wide variety of different access
tubes, it is significant that it can be used with standard
hypodermic needles, standard fistula needles, large fistula
needles, e.g. 16 gauge, 14 gauge, or larger, and the like. Prior
port designs which employ a septum require the use of relatively
small non-coring Huber needles or the use of a combination
tube/stylet in order to avoid significant damage to the septum. The
same is true of ports which employ slit valves through which a tube
must pass, such as many of the Ensminger designs described above.
In all cases, the needle or other access tube will be rigid and
possess sufficient column strength in order to actuate a linkage
for relieving clamping of the conduit, as described in more detail
below.
[0032] The port of the present invention is also advantageous since
it will not generally be damaged by use of an inappropriately sized
needle or other access tube. While most prior art ports can be
damaged through use of the wrong type or size of needle, the port
of the present invention will not be damaged by larger needles
(which simply engage the access aperture and do not pass into the
port) or by smaller needles (which enter the access aperture but
pass harmlessly into the interior of the base). In particular, the
passage in the access port which receives the needle or other
access tube may have at least one bend, usually a 90.degree. elbow,
which presents a surface which is engaged by a smaller needle. By
forming or backing the passage from a material which is harder than
the needle, e.g. a stainless steel, the port will be protected from
any damage from improper insertion of a small needle.
[0033] An exemplary access port 10 comprising a base 12 and
flexible conduit 14 is illustrated in FIGS. 1, 2, 2A, 3, and 3A. As
shown in FIG. 1, the flexible conduit 14 extends from the base 12
and terminates at a distal end 16 which is suitable for direct
anastomosis (suturing) to a blood vessel. Suitable conduit
structures are described in U.S. Pat. No. 5,562,617, the full
disclosure of which is incorporated herein by reference. Exemplary
conduit structures may be composed of silicone rubber.
[0034] The base 12 of access port 10 comprises an upper shell 18, a
base plate 20, an internal cylinder 22, and a vertically
reciprocating plunger 23 disposed within an actuator block 24,
where the assembly of the plunger and actuator block are together
disposed within the cylinder 22. As shown in FIGS. 2 and 2A, a
spring 26 urges the plunger 23 and actuator block 24 upwardly
relative to the base 20. When the plunger 23 and actuator block 24
are in their upward position, the conduit 14 is pinched closed
between an upper lip 28 which is a portion of the wall of cylinder
22 and a lower lip 30 which is portion of the actuator block 24. A
proximal end of the conduit 14 is connected to the lower end of a
tube 32 which depends into an interior volume of the actuator block
24. The depending tube 32 provides an axial bore 34 for receiving a
needle N, as illustrated in FIGS. 3 and 3A. A tapered region 33 is
formed near the upper end of axial bore 34 and is sized to engage
and seal against the outer side wall of a needle or other access
tube which is introduced into the bore, as best seen in FIG.
3B.
[0035] The needle N is introduced through an opening 36 at the
upper end of the axial bore 34. Typically, though not necessarily,
the opening 36 has a slight chamfer (conical shape) which allows
the needle N to be introduced into the bore 34. A pair of balls 40
are disposed in an upper portion of the tube 32 and contained
within a circular aperture 42 in the shell 18 on the actuator block
24 as in its raised configuration, as shown in FIG. 2. When needle
N is introduced through the opening 36, it will encounter the balls
40 and depress the plunger 23 and the actuator block 24 downward
until the block reaches its lower configuration, as shown in FIG.
3. At that time, the balls 40 will move radially outward into an
expanded portion or ramp 44 of the aperture 42. The balls 40 will
thus become locked within the expanded portion or ramp 44, holding
the actuator block 24 in its lowered position, so long as the
needle N remains in place.
[0036] When the actuator block 24 has been lowered, as shown FIGS.
3 and 3A, the opposed lips 28 and 30 are opened in order to relieve
external clamping on the conduit 14. Thus, as the needle N is
inserted into the access port 10, the clamping mechanism which has
previously closed the flexible conduit 14 will be opened. When the
needle N is removed, the spring 26 will urge the actuator block 24
upwardly, and the access port will return to the configuration
shown in FIGS. 2 and 2A.
[0037] Conveniently, a silicone overmolding 50 is provided around
the base of the access port 10 in order to facilitate implantation
of the access port. A flange 52 extending radially outwardly from
the base plate 20 will include holes (not illustrated) for suturing
into tissue. The inclusion of the silicone overmolding 50 will
prevent tissue ingrowth into the holes. Preferably, a silicone seal
54 will be provided between an internal surface of the upper shell
18 and an upper portion of the tube 32. The silicone seal 54
prevents the intrusion of blood or other fluids from surrounding
tissue and/or which may leak from the needle N into the interior of
the access port 10.
[0038] In a preferred aspect of the access port 10 of the present
invention, the axial bore 34 will be tapered in the downward
direction, as best seen in FIG. 3B over region 33. The size of the
bore and degree of the taper will be selected to frictionally
engage conventional needles or other access tubes so that a tight
seal is formed as the access tubes are inserted into the axial bore
34. The taper also provides a stop so that the needle N will not
penetrate into the horizontal lumen defined by the conduit 14.
[0039] It can thus be seen that the combination of needle, access
port 10, and flexible conduit 14 provides a substantially
continuous and smooth flow path for fluids from and/or to the
patient's vascular system. In particular, the use of external
clamping for closing flow through the conduit 14 eliminates the
need for an internal valve structure within the conduit or
elsewhere within the access port to define a valve seat, i.e. that
portion of the valve which closes to inhibit flow therethrough. The
particular linkage shown for relieving clamping from the flexible
conduit is simple, reliable, and relatively inexpensive to produce.
Very few moving parts are needed, yet a positive seal is reliably
achieved every time the needle N is withdrawn from the access port
10. Moreover, once the needle N is introduced into the access port
10, the clamp mechanism is locked in its open configuration to
assure that full flow through the lumen of the flexible tube and
other portions of the access port are maintained.
[0040] Referring now to FIGS. 4A and 4B, an additional embodiment
of an access port 500 constructed in accordance with the principles
of the present invention includes a body 512 having a nipple 514
extending laterally outward from the body 512. The nipple 514 is
suitable for connection to a flexible conduit (not shown). The body
512 includes an upper shell 518, a base plate 520, an internal
cylinder 522, a vertically reciprocating plunger 523 and an
actuator block 524. The plunger 523/actuator block 524 as shown in
their vertically raised position in FIG. 4A and its vertically
depressed or lowered configuration in FIG. 4B.
[0041] Since the conduit does not extend into the base 512, the
port embodiment 500 of FIGS. 4A and 4B employs a separate pinch
tube 525, where the pinch tube is pinched closed between an upper
lip 528 which is part of the cylinder 522 and a lower lip 530 which
is part of the reciprocating actuator block 524. When the actuator
block 524 is lowered, as shown in FIG. 4B, the external clamping of
the pinch tube 525 is relieved.
[0042] The actuator block 524 is urged upwardly by spring 526 which
is mounted over a pin 527, and the plunger 523 comprises an axial
bore 534 for receiving a needle N, as shown in FIG. 4B. The needle
N passes through aperture 536 and into the passage 534 in the
plunger 523. As the needle enters the passage 534, it passes
through opposed balls 540 which first cause lowering of the plunger
523 and the actuator block 524 and then are captured in an expanded
portion or ramp 544 of the passage 545, as illustrated in FIG.
4B.
[0043] While the entry of needle N into the passage 534 and through
opposed balls 540 may be effected simply by inserting the needle
vertically downward, once the needle is fully lowered, and engaged
by the tapered wall of passage 534 (as shown in FIG. 4B), the valve
is "locked" open by the balls 540. The needle is held in place by
friction fit in the tapered region of the passage 534. In addition,
the static friction of the balls against the tube may help to hold
the access tube in the passage. Such retention protects the patient
against accidental loss of the needle. It has been found that
simple removal techniques allow the needle to be pulled from the
port without significant hindrance. Thus, the combination of
opposed balls 540 and the expanded portion 544 for capturing the
balls not only locks the valve open, it also secures the needle in
place until it is desired to remove the needle.
[0044] Referring now to FIGS. 5A and 5B, an alternative valve
structure for use in the implantable ports of the present invention
is illustrated. Instead of employing a pinch valve, as previously
described, the ports may employ a sliding valve 600 or a
reciprocating block 602 is formed within the base enclosure 604
(only a portion of which is illustrated). The reciprocating block
602 defines an inlet portion 606 of a passage through the port. An
outlet portion 608 of the passage is also provided in the port.
Initially, when no needle is present a spring 610 urges the
reciprocating block 602 upward so that a side portion 612 of the
passage is out of alignment with the outlet portion 608. Thus, the
sliding valve structure 600 is closed. By introducing a needle N or
other access tube into the valve structure 600, the reciprocating
block 602 is lowered so that the side branch 612 of the passage
comes into alignment with the outlet portion 608, as illustrated in
FIG. 5B. The valve is thus open. The valve can be held in the open
position by a pair of opposed balls 620 which are received in an
enlarged recess 622, generally as described above in connection
with the previous embodiments.
[0045] Referring now to FIGS. 6A and 6B, an alternative valve
structure for use in the implantable ports of the present invention
is illustrated. Instead of employing a pinch valve or sliding
valve, as previously described, a port may employ a duckbill or
miter valve. An exemplary port 700 having duckbill valve assembly
comprises a base having a passage 701, balls 702, a receptacle or
ramp 703, an axial bore 704, a vertically reciprocating plunger
705, and a duckbill valve 707. A spring 706 urges the plunger 705
upwardly relative to the duckbill valve 707. When the plunger 705
is in its upward position, the duckbill valve 707 is closed and the
conduit 708 is not accessible. A tapered region 709 is formed near
the upper end of the axial bore 704 and is sized to engage and seal
against the outer side wall of a needle or other access tube which
is introduced into the bore 704.
[0046] A needle N is introduced through an opening 710 at the upper
end of the axial bore 704. Typically, though not necessarily, the
opening 710 has a slight chamfer (conical shape) which allows the
needle N to be introduced into the bore 704. A pair of balls 702 is
disposed in the passage 701 and held in position by the plunger 705
in its raised configuration, as shown in FIG. 6A. When needle N is
introduced through the opening 710, it will encounter the balls
702, urging the balls forwardly to engage and depress the plunger
705 downward until the plunger 705 reaches its lower configuration
where the duckbill valve 707 is opened, as shown in FIG. 6B. At
that time, the balls 702 move radially outward into a receptacle
703. The balls 702 thus become locked within the receptacle 703,
holding the plunger 705 in its lowered position, so long as the
needle N remains in place.
[0047] In a preferred aspect of the access port 700 of the present
invention, the axial bore 704 will be tapered in the downward
direction. The size of the bore and degree of the taper will be
selected to frictionally engage conventional needles or other
access tubes so that a tight seal is formed as the access tubes are
inserted into the axial bore 704. The taper also provides a stop so
that the needle N will not penetrate the end of the plunger 705. In
a further preferred aspect of the access port 700 of the present
invention, the plunger assembly 705 will comprise an end cap 711
affixed to its end. The cap 711 will be adapted to withstand repeat
contact with the access tube, resisting passage of the tube such
that the tube will not penetrate or damage the valve 707.
[0048] Although the foregoing invention has been described in some
detail by way of illustration and example, for purposes of clarity
of understanding, it will be obvious that certain changes and
modifications may be practiced within the scope of the appended
claims.
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