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Description  |
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BACKGROUND OF THE INVENTION
Hemostasis valves are currently used on catheters for performing
percutaneous transluminal coronary angioplasty (PTCA), as well as
angiographic procedures, for example, where X-ray contrast fluid is
inserted into the coronary artery.
In PTCA, stenotic regions of coronary blood vessels are dilated by
advancing a dilatation catheter through blood vessels into the stenotic
region. The dilatation catheter advances over a guide wire, which guide
wire moves forward, followed by the catheter, followed by another advance
of the guide wire, etc. The guide wire-dilatation catheter system may be
introduced through a guiding catheter to facilitate its placement.
To prevent the leakage of blood out of the proximal end of the catheter, a
hemostasis valve is provided at the proximal end, to prevent seepage of
blood between the guide wire and the catheter. For example, currently,
numerous types of hemostasis valves are known. See for example Stevens,
U.S. Pat. No. 4,000,739. Another design of hemostasis valve is the
Tuohy-Borst type, making use of an adJustable, compressive sleeve which is
axially compressed about the guide wire that it seals by means of a
two-piece, screw threaded housing. Other designs may use an "O" ring and a
tapered seat instead of a sleeve.
Many designs require tightening of the valve when high pressure X-ray
contrast fluid or the like is run through the catheter. However, with such
high pressure sealing, the guide wire cannot be advanced in effective
manner, so the valve, such as a Tuohy-Borst valve, must be loosened so
that the operator can "feel" any resistance encountered by the forward
advancement of the guide wire, during the operation of advancing the guide
wire through blood vessels.
The degree of loosening of the valve can be critical. If excessively
loosened, low pressure leakage may occur. If loosened too little, the
guide wire cannot be effectively advanced. Accordingly, it turns out that
for the most effective performance of PTCA and angiography procedures, a
hemostasis valve which is highly controllable is needed, so that the guide
wire can be easily advanced, while low pressure leakage is prevented on an
easy, reliable basis, without the need for great skill and experience in
operation of the valve.
By this invention, a hemostasis valve is provided with reliable sealing
against low pressure leakage around a guide wire or the like. At the same
time an adjustable seal is also provided which may be adjusted to seal
against high pressures. Accordingly, the adjustable seal may be applied or
released as desired, but, preferably, a low pressure seal may be
constantly present to stop leakage upon release of the high pressure seal.
Thus, manipulation of the high pressure seal is less critical, and
requires less skill in order to avoid leakage.
Also, the surgeon who is manipulating a typical catheter for entering
coronary blood vessels, for example, is overburdened with respect to
things to hold and manipulate during this process. By this invention,
improved efficiency of adjustment of the adjustable valve of this
invention may be provided to relieve the burden on the surgeon.
DESCRIPTION OF THE INVENTION
In this invention, a hemostasis valve defines first and second tubular
housings, said housings being connected together in axial, telescoping,
screw-threaded relation, whereby relative rotation of the housings causes
them to advance and retract relative to each other.
The first housing defines a bore which includes an enlarged chamber
portion. A tubular, resilient gasket is retained in the enlarged chamber
portion. The second housing defines an end portion which projects into the
bore of the first housing to press against the tubular, resilient gasket
with variable pressures depending on the relative rotational position of
the housings.
Thus, a wire member can pass through the bores of the tubular housings and
the tubular, resilient gasket, and a variable pressure seal may be applied
to the wire at the tubular, resilient gasket by rotational adjustment of
the housings. As the housings are brought closer together, they compress
the tubular, resilient gasket in longitudinal manner. This, in turn,
causes the bore of the tubular gasket to collapse inwardly, pressing
against a wire portion that occupies the bore, thus providing a seal which
presses against the wire with force that is dependent on the rotational
position of the housings.
A second, apertured, resilient gasket, spaced from the tubular, resilient
gasket, is also present to provide the valve with a second, low-pressure
sealing site for the wire member extending through the aperture of the
second gasket. Thus, the same wire member that is sealed with the first
tubular, resilient gasket may also extend through the aperture in the
second gasket, which is proportioned to be slightly smaller than the
diameter of the wire. Thus a second seal may be provided which typically
is of relatively low pressure resistance so that it does not seriously
interfere with advancement of the wire in the manner described above.
Nevertheless, the second seal is sufficient to prevent leakage when the
first, tubular, resilient gasket is not being compressed, and thus not
providing a strong seal against the wire. Accordingly, the first, tubular,
resilient gasket may be intermittently released so as to provide little or
no sealing, for advancing the wire member, but still low pressure sealing
is provided by the second gasket.
Typically, the second gasket is carried on the second housing. An end piece
with a laterally extending handle may hold the second gasket in coaxial
relation with the second housing to permit the aperture of the second
gasket to align with the bores of the respective housings and the bore of
the first, tubular, resilient gasket.
The first housing may define branched, tubular connection means
communicating with the bore of the first housing. When the valve of this
invention is part of a catheter for entering coronary blood vessels, this
branched, tubular connection may be used to insert contrast fluid, where
local pressures of injection of the contrast fluid into the system may
reach several hundred pounds per square inch.
During this operation, the first, tubular, resilient gasket may be
longitudinally compressed between the two housings for high pressure
sealing around the advance wire. However, when it is desired to advance
the wire, the two housings may be rotated relative to each other to
release the high pressure sealing so that advancement of the wire may be
facilitated, but the second gasket still provides adequate sealing while
the wire is being advanced.
DESCRIPTION OF DRAWINGS
Referring to the drawings, FIG. 1 is a plan view of a catheter for entering
coronary blood vessels, carrying the hemostasis valve of this invention.
FIG. 2 is a fragmentary, enlarged, elevational view of the catheter of FIG.
1 showing exterior details of the hemostasis valve.
FIG. 3 is a longitudinal sectional view taken along line 3--3 of FIG. 2.
FIG. 4 is a transverse sectional view taken along line 4--4 of FIG. 3.
DESCRIPTION OF SPECIFIC EMBODIMENT
Referring to the drawings, FIG. 1 shows a catheter 10 for entering coronary
blood vessels. Specific details of catheter 10 are not shown since the
catheter per se, except as otherwise described herein, may be a catheter
for performing an angiographic procedure of conventional design.
At the proximal end of catheter 10 themostatsis valve 12 is provided, being
of a design in accordance with this invention. Valve 12 defines first
tubular housing 14 and second tubular housing 16. As shown in FIG. 3,
second housing 16 defines a threaded projection 18 which fits into
threaded recess 20 defined in second housing 14 so that relative rotation
of the housings causes them to advance and retract relative to each other,
depending upon the direction of rotation.
First housing 14 may also have branched tubular connection 22 which may be
used for providing fluids, such as x-ray contrast fluid and saline
solution to the bore of an angiographic catheter.
Stylet or advancement wire 24 may be stainless steel coated with
polytetrafluoroethylene, and may pass through the bores of the respective
housings 14, 16 in conventional manner.
As shown in FIG. 3, first housing 14 defines a bore which includes an
enlarged chamber portion having annular shoulder 25 for retaining a
tubular, resilient gasket 26 in the enlarged chamber portion. As shown,
threaded end portion 18 of second housing 16 may press against first
tubular, resilient gasket 26 to press it against annular shoulder 25 in a
longitudinal direction. The effect of this is to cause bore 28 of first
gasket 26 to constrict, with the effect that if wire 24 is present, bore
28 will constrict upon it, forming a seal of relatively high pressure,
depending upon the amount of compression given to first gasket 26 by the
relative rotational position of housings 14, 16. The pitch of the mating
threads of 14 and 16 may be chosen so that a relative rotation of
90.degree. between 14 and 16 will cause 26 to change from the low pressure
seal mode to the high pressure seal mode. Stops can be provided on items
14 and 16 so that, often initial assembly, relative rotation between 14
and 16 will be limited to 90.degree. thus making the valve easier to use
as its open and closed positions are now defined exactly.
Thus, when a high pressure seal is formed against wire 24 at first gasket
26, high pressure fluids may be injected through side arm 22 into the bore
of first housing 14 without leakage through first gasket 26. In the event
that a small amount of leakage is detected, one can simply tighten the
relationship of housings 14, 16 to provide added sealing pressure.
When the desired fluid has been injected through side arm 22 and the
pressure has dropped once again, one may wish to advance wire 24 through
catheter 10 again. This is not easily done with a high pressure seal at
first gasket 26, because even if wire 24 can be forced through gasket 26,
one loses the needed sensitive feel about what the distal end of wire 24
is encountering within a vein or artery of the patient. Accordingly, one
may rotate housings 14, 16 to reduce the longitudinal pressure on first
gasket 26, with a consequent reduction of the pressure of the seal of the
gasket bore 28 against wire 24.
To prevent leakage when the high pressure seal provided by first gasket 26
is released, a second apertured resilient gasket 30 is provided, shown in
FIG. 3 to be carried on second housing 16 and held in position by end
piece 32. End piece 32 may be made of a rigid plastic material, and may
define a laterally extending handle 34 to provide ease in turning second
housing 16 relative to first housing 14. End piece 32 may be glued in
position on housing 16 and, if desired, housing 16 may have a square or
other non-circular cross section, which cross section is matched by mating
flange 36 of end piece 32 to prevent rotational slippage between second
housing 16 and end piece 32.
Second gasket 30 defines a bore 38, which may be slightly undersized with
respect to the diameter of wire 24, to provide a continuous, typically low
pressure seal with wire 24. The level of pressure of this seal is
generally selected to permit advancement of wire 24 without serious
interference with the "sensitive feel" that the surgeon must have as he
advances wire 24 into a blood vessel. For example, the diameter of wire 24
may be 0.014 inch. Similarly, the diameter of bore 28 of first gasket 26
may be 0.017 inch when unstressed. The diameter of bore 28, of course,
reduces to that of wire 24 with increased pressure, when the high pressure
seal is desired. The diameter of bore 38 may be 0.010 inch.
First housing 14 may also define a tapered luer tip 40 to facilitate
connection between housing 14 and catheter 10.
Gaskets 26, 30 may be made of any desired elastic material; for example
silicone rubber or another similar material suitable for contact with
blood.
Hemostasis valve 12 may be modified to receive a dilatation catheter rather
than a wire through bores 28, 38, with catheter 10 serving as a blood
vessel access catheter.
Accordingly, catheters used in dilation procedures or angiographic
catheters, as specific examples, may carry a hemostasis valve which is
adjustable to provide desired and variable high pressure sealing, so that
blood or other fluid will not escape out the proximal end of the catheter
during use. When the high pressure is released, as is generally desired
for advancement of wire 24, one can remove the pressure by proper relative
rotation of housings 14, 16 without concern that there will be spillage
out of the proximal end of the catheter, because of the presence of a
constant, typically low pressure seal against wire 24 provided by second
gasket 30.
The above has been offered for illustrative purposes only, and is not
intended to limit the scope of the invention of this application, which is
as defined in the claims below.
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