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Claims  |
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It is claimed:
1. A catheter device for accessing an internal tissue site along a vessel
path from an external body access site, comprising:
a catheter having an inner lumen extending between proximal and distal
ends, an inflatable balloon disposed in a distal end region of the
catheter, means communicating the catheter lumen with the balloon, to
allow bidirectional fluid flow between the balloon and the catheter lumen,
and means defining an aperture disposed distally to the communicating
means between the lumen and the balloon, such that when the aperture is
blocked, fluid supplied through the lumen is forced into the balloon,
a flexible guide wire having proximal and distal ends and carried in said
catheter for axial sliding movement therein, and
valve structure defined by said aperture and guide wire designed to block
the aperture at one or more selected guide wire positions, to permit the
catheter balloon to be inflated by supplying fluid through the catheter
lumen and to allow the balloon to deflate when the guide wire is moved
away from said selected positions.
2. The device of claim 1, wherein the catheter is formed of a tube having
an inflatable distal end section which forms said balloon, and said ring
is positioned within the inflatable end section.
3. The device of claim 1, wherein the catheter is formed of a tube which
has an inflatable intermediate section forming said balloon, and said ring
is positioned within the tube, distal to said inflatable section.
4. The device of claim 1, wherein the catheter is formed of a tube having
an inflatable distal end section which forms said balloon, and said ring
is positioned within the inflatable end section.
5. The device of claim 1, wherein the inflatable balloon is disposed along
a distal end region of a catheter tube, the balloon communicates with the
inner lumen of the catheter through an opening in the tube which is
adjacent the tube'distal end, but proximal thereto, and the valve
structure includes an elastomeric annular seal carried on the guide wire
for contacting and sealing the inner lumen.
6. A catheter device for accessing an internal tissue site along a vessel
path from an external body access site, comprising
a catheter having an inner lumen extending between proximal and distal
ends, an inflatable balloon disposed adjacent the distal catheter end,
means communicating the catheter lumen with the balloon, to allow
bidirectional fluid flow between the catheter and lumen, and means
defining an aperture disposed distally to the communicating means such
that when the aperture is blocked, fluid supplied through the lumen is
forced into the balloon,
a flexible guide wire having proximal and distal ends and carried in said
catheter for axial sliding movement therein, and
valve structure defined by said aperture and guide wire designed to block
the aperture at one or more selected guide wire positions, to permit the
catheter balloon to be inflated by supplying fluid through the catheter
lumen, and to allow the balloon to deflate when the guide wire is moved
away from such selected positions,
wherein said catheter aperture is defined by an annular ring mounted to the
distal end of the catheter, and is dimensioned to receive the distal end
segment of the guide wire freely therethrough, and the valve structure
includes an annular enlargement on the guide wire proximal to said end
segment, dimensioned to block the aperture, when the enlargement is
advanced against the ring.
7. The device of claim 6, wherein the catheter is formed of a tube which
has an intermediate inflatable section forming said balloon, and said ring
is positioned within the tube, distal to said inflatable section.
8. The device of claim 6, wherein the catheter is formed of a tube which
has an inflatable intermediate section, and which further includes an
axially compressible member disposed inside the balloon, along said
intermediate section, to maintain the diameter of said intermediate
section substantially the same as the adjacent tube regions, when the
balloon is in a deflated state.
9. The device of claim 8, wherein the compressible member is a compressible
coil.
10. The device of claim 8, wherein the inflatable section is a
substantially inelastic sleeve which is maintained in a substantially
stretched condition by the coil, in an uninflated state.
11. The system of claim 6, wherein a distal end portion of the guide wire
is ensheathed in a substantially constant-diameter flexible coil.
12. The device of claim 6, which further includes means attached to the
proximal end of the guide wire for torquing the wire along its axis, to
orient the distal end of the wire in a selected direction.
13. A method of accessing an internal body site along a narrow-vessel
tortuous path which includes at least one branch point at which the path
follows the larger-diameter of two branch vessels, and at least one branch
point at which the path follows the smaller diameter of two branch
vessels, said method comprising,
providing a catheter device composed of (a) a catheter having an inner
lumen extending between proximal and distal ends, an inflatable balloon
disposed in a distal end region of the catheter, means communicating the
catheter lumen with the balloon, to allow bidirectional fluid flow between
the balloon and the catheter lumen, and means defining an aperture
disposed distally to the communicating means between the lumen and the
balloon, such that when the aperture is blocked, fluid supplied through
the lumen is forced into the balloon, (b) a flexible guide wire having
proximal and distal ends and carried in said catheter for axial sliding
movement therein, and (c) valve structure defined by said aperture and
guide wire designed to block the aperture at one or more selected guide
wire positions, to permit the catheter balloon to be inflated by supplying
fluid through the catheter lumen and to allow the balloon to deflate when
the guide wire is moved way from said selected positions,
advancing the wire along the path,
when the branch point at which the vessel path follows the larger-diameter
of two branch vessels is reached, placing the guide wire axially in a
position to block said aperture, and supplying fluid through the catheter
to inflate the balloon, whereby the distal end of the catheter can be
carried by fluid flow into larger-diameter vessel, and
when a branch point at which the vessel path follows the smaller diameter
of two branch vessels is reached, torquing said guide wire to orient the
guide wire tip in the direction of the smaller-diameter vessels, and
advancing the catheter into such vessel.
14. The method of claim 13, which further includes inflating said balloon
when the catheter distal end encounters a region of vessel constriction,
thereby to extend and relax the constricted vessel region and facilitate
movement of the catheter device therethrough.
15. A catheter device for accessing an internal tissue site along a vessel
path from an external body access site, comprising
a catheter having an inner lumen extending between proximal and distal
ends, an inflatable balloon disposed adjacent the distal catheter end,
means communicating the catheter lumen with the balloon to allow
bidirectional fluid flow between the catheter and lumen, and means
defining an aperture disposed distally to the communicating means, such
that when the aperture is blocked, fluid supplied through the lumen is
forced into the balloon,
a flexible guide wire having proximal and distal ends and carried in said
catheter for axial sliding movement therein, and
valve structure defined by said aperture and guide wire designed to block
the aperture at one or more selected guide wire positions, to permit the
catheter balloon to be inflated by supplying fluid through the catheter
lumen, and to allow the balloon to deflate when the guide wire is moved
away from such selected positions,
wherein said catheter aperture is defined by an annular ring mounted to the
distal end of the catheter, and is dimensioned to receive the distal end
segment of the guide wire snugly, in a sealed fashion.
16. A method of accessing an internal body site along a narrow-vessel
tortuous path which includes at least one branch point in which the path
follows the larger-diameter of two branch vessels, and at least one branch
point at which the path follows the smaller diameter of two branch
vessels, said method comprising,
providing a catheter device composed of (a) a catheter having an inner
lumen extending between proximal and distal ends, an inflatable balloon
disposed in a distal end region of the catheter, means communicating the
catheter lumen with the balloon, to allow bidirectional fluid flow between
the balloon and the catheter lumen, and means defining an aperture
disposed distally to the communicating means between the lumen and the
balloon, such that when the aperture is blocked, fluid supplied through
the lumen is forced into the balloon, (b) a guide wire having proximal and
distal ends and carried in said catheter for axial sliding movement
therein, and (c) valve structure defined by said aperture and guide wire
designed to block the aperture at one or more selected guide wire
positions, to permit the catheter balloon to be inflated by supplying
fluid through the catheter lumen and to allow the balloon to deflate when
the guide wire is moved away from said selected positions,
advancing the wire along the path,
when the branch point at which the vessel path follows the larger-diameter
of two branch vessels is reached, placing the guide wire axially in a
position to block said aperture, and supplying fluid through the catheter
to inflate the balloon, whereby the distal end of the catheter can be
carried by fluid flow into larger-diameter vessel, and
when a branch point at which the vessel path follows the smaller diameter
of two branch vessels is reached, torquing said guide wire to orient the
guide wire tip in the direction of the smaller-diameter vessels, and
advancing the catheter into such vessel,
wherein the valve structure in the catheter is defined by a ring mounted in
the distal end of the catheter, and a guide wire enlargement which abuts
the ring, when the guide wire is moved distally to a valve-closure
position, which further includes advancing the guide wire distally, after
valve closure, to advance the guide wire and catheter as a unit along the
vessel path. |
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Claims |
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Description |
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FIELD OF THE INVENTION
This invention relates to catheter devices and methods for accessing
internal body target sites along a small-vessel path.
BACKGROUND OF THE INVENTION
Catheters are being used increasingly as a means for delivering diagnostic
or therapeutic agents to internal target sites, and to perform mechanical
functions on vasculatures that can be accessed through the circulatory
system. For example, in angiography, catheters are designed to deliver a
radiopaque agent to a target site within a blood vessel, to allow
radiographic viewing of the vessel and blood flow characteristics near the
release site. For the treatment of localized disease, such as solid
tumors, catheters allow therapeutic agents to be delivered to the target
site at a relatively high concentration, with reduction in drug delivery
to nontarget sites. Methods for producing localized vasoocclusion in
target tissue regions, by catheter injection of a vasoocclusive agent,
have been described (coowned U.S. patent application for "Hyperthermic
Treatment of Tumors," Ser. No. 751,605, filed July 2, 1985).
Often the target site which one wishes to access is in a tissue, such as
brain, liver or kidney, which requires catheter placement along a tortuous
path through small vessels or ducts, such as arterial vessels or biliary
ducts. Typically, the vessel path will include vessel branch points at
which the path may follow either a relatively larger-diameter, higher-flow
branch vessel, or a relatively smaller, lower-flow branch vessel.
Heretofore, three general types of catheters have been developed for
accessing internal target sites. One type is a torqueable catheter having
relatively rigid tube construction and large-diameter lumen. in
particular, the catheter tube may be formed as a braided fiber or wire
laminate which has high torque properties. The distal portion of the
catheter can be made narrower and more flexible by eliminating laminate
windings or braid from this portion of the catheter, but this compromises
torque transmission. Torqueable catheters of this type are generally too
large in diameter and too rigid to be safely advanced through narrow,
tortuous vessel or duct paths.
Another type of guidable catheter is a guide-wire catheter which contains a
single-lumen catheter used in conjunction with a flexible, torqueable,
guide wire which can be moved slidable within the catheter. In a typical
catheter-placement operation, the wire is advanced along the vessel
pathway, using wire torquing to orient the somewhat bent tip of the wire
along the selected path, i.e., into and through selected branch vessels
and/or regions of sharp bends. The catheter is then advanced along the
wire with the wire held in place. The wire and catheter are alternately
advanced in this manner until the target site is reached. Thereafter, the
wire can be removed to allow fluid delivery through the catheter into the
site. Since the wire can be both torqueable and quite flexible, and the
catheter can be a thin-walled flexible tube, the catheter device is well
suited for accessing sites via small-diameter tortuous paths.
Another general class of guidable catheters have a distal-end balloon which
can be partially inflated to carry the catheter in the direction of
highest blood flow, and therefore along a vessel path having maximum blood
flow. The balloon may be further inflated, at a selected target site, for
purposes of occluding blood flow, or for anchoring the catheter end at the
selected site. Extending the balloon to contact the walls of a blood
vessel can also be useful in relaxing spasmodic vessel muscles, resulting
in less vessel constriction. Balloon catheters thus have the advantage
over guide-wire catheters in that they can take advantage of blood flow
for advancing along a vessel pathway, and various advantages relating to
balloon contact with vessel walls can be achieved.
In one construction, the balloon catheter has a double-lumen construction,
where one lumen communicates with the distal balloon, for transferring
fluid to or from the balloon. The second lumen allows delivery of injected
material, such as radio-opaque tracer material or therapeutic agent, into
the target site. One advantage of the double-lumen catheter is the ability
to inflate the balloon to relatively high pressure, which is particularly
useful when the balloon is used for stretching a vessel wall, in a
catheter treatment for removing vessel plaque. Also, the catheter can be
firmly anchored at the target site when the balloon is in a highly
inflated state. The double-lumen balloon catheter, however, is not well
suited for guidance along small-diameter, tortuous pathways, since the
catheter typically has a relatively large outer shaft diameter, and these
shafts are generally relatively inflexible. Alternatively, the two
catheter lumens may be made relatively small, but here fluid passage
through the lumens is slow and limited to low-viscosity agents. Also,
since the catheter is guided by blood flow, the device is limited in use
to vessel paths with highest blood flow.
In a second balloon-catheter construction, the catheter has a single-lumen
tube which communicates with a slow-leak balloon to the distal tube end.
In operation, fluid is supplied through the tube at a slow controlled
rate, to maintain the balloon at an inflated condition which promotes
fluid-directed movement through the vessel path. The single lumen tube can
have a small-diameter, highly flexible construction which permits movement
along a small-diameter, tortuous vessel path. The ability to guide the
catheter, however, is limited to vessel or duct branches with greater
flow, as above, so the catheter is not generally useful for accessing a
site against the direction of flow, or along a pathway which includes
relatively low-flow branches. Another limitation of the single-lumen
catheter is that the slow-leak principle of balloon inflation does not
allow for high balloon pressures, and therefore the catheter would not be
useful, for example, in stretching a vessel for purposes of plaque
removal. By the same token, since fluid released from the balloon is
somewhat slow, the catheter is not well-suited to delivery of fluid
material rapidly at the target site.
A third balloon catheter construction has a single-lumen catheter which
communicates with a sealed balloon. The catheter is able to access
small-vessel tortuous paths and allows relatively high balloon inflation
pressures. The catheter is limited, however, to vessel paths of highest
blood flow, and of course cannot be used to deliver fluid to the target
site.
SUMMARY OF THE INVENTION
It is a general object of the invention to provide an improved catheter
device for accessing a target site along a small-vessel tortuous path.
A related object of the invention is to provide such a device which
overcomes or reduces above-discussed problems and limitations associated
with prior art guidable catheters.
A more specific object of the invention is to combine advantages of balloon
catheters and guide-wire catheters in a single device.
The invention includes a catheter device for accessing an internal tissue
site along a vessel path from an external body access site. A catheter in
the device has an inner lumen extending between proximal and distal
catheter ends, and includes an inflatable balloon at the distal catheter
end which communicates with the inner lumen. An aperture in the catheter
is disposed distally of the communication between lumen and balloon, such
that when the aperture is blocked, fluid supplied through the lumen is
forced into the balloon. The device also includes a guide wire carried in
the catheter lumen for axial sliding movement therein. The catheter and
guide wire define a valve structure which acts to block the aperture at
one or more selected wire positions, to permit the catheter balloon to be
inflated by supplying fluid through the catheter lumen.
The balloon may be carried at the distal end of catheter, or along a distal
end section of a catheter tube, or formed as an intermediate inflatable
section of a catheter tube. In the latter construction, the catheter may
further include an axially compressible member, preferably a spring coil,
disposed inside the balloon along the intermediate section, providing for
column support in the balloon region, and for maintaining the diameter of
the intermediate section substantially the same as the adjacent tube
regions, when the balloon is in a deflated state. Where the inflatable
section is a substantially inelastic sleeve, the coil acts to maintain the
sleeve in a substantially stretched condition even when the balloon is
uninflated.
In one general embodiment, the catheter aperture is defined by an annular
ring mounted in the distal end of the catheter, and which is dimensioned
to receive a distal end segment of the guide wire freely therethrough,
i.e., with wire clearance. The valve structure is defined by this ring and
an annular enlargement carried on the guide wire which is dimensioned to
block the aperture when the enlargement is advanced against the ring.
Where the catheter is formed of a tube having an inflatable distal end
balloon, the ring is positioned at the distal end of the balloon. Where
the balloon is disposed along an end section of the catheter tube, the
ring is disposed distal to the balloon end section or distal to an opening
communicating the catheter tube with the balloon.
In another general embodiment, the catheter aperture is defined by an
elastomeric opening disposed in the distal end of the catheter, and
dimensioned to receive a distal end segment of the guide wire snugly
therethrough, to seal the opening. The valve structure here is defined by
the elastomeric opening and the guide wire, which preferably has a
constant diameter along distal end segment. As above, where the catheter
is formed of a tube having an inflatable distal end balloon, the opening
is positioned at the distal end of the balloon. Where the balloon is
carried on an end section of the catheter tube, the ring is disposed
distal to the balloon section or distal to an opening communicating the
catheter tube with the balloon.
A third general embodiment employs the above catheter construction in which
the balloon is an inflatable sleeve carried on a distal end segment of the
catheter tube, where the catheter lumen communicates with the inflatable
sleeve through an opening in the catheter tube. The guide wire in this
embodiment has an elastomeric seal which forms a seal with the interior
walls of the catheter lumen. The valve structure here is formed by the
seal acting against the interior walls of the catheter lumen. The balloon
can be inflated by moving the guide wire seal to a position within the
catheter tube, just downstream of the opening communicating the lumen and
the balloon, and supplying fluid through the tube.
The invention also includes a method for accessing an internal body site
along a narrow-vessel tortuous path which includes some branch points in
which the path follows the larger-diameter of two branch vessels, and some
in which the path follows the smaller diameter of two branch vessels. The
method employs a catheter device of the type described in which a
single-lumen balloon catheter and a guide wire movable therein
therethrough define a valve structure which can be manipulated to block
the distal end of the catheter, for purposes of supplying fluid to and
inflating the balloon.
In the accessing method, the guide wire and catheter are advanced along the
vessel pathway toward the target site. When a branch point at which the
vessel path follows the larger-diameter of two branch vessels is reached,
the guide wire is placed in a position to close the balloon valve, and the
balloon is inflated, allowing the distal end of the catheter is carried by
fluid flow into larger-diameter vessel. When a branch point at which the
vessel path follows the smaller diameter of two branch vessels is reached,
the guide wire can be torqued to orient the guide wire tip in the
direction of the smaller-diameter vessel, and the catheter then advanced
into the smaller vessel, with the catheter balloon preferably in an
uninflated state.
The catheter can also be manipulated for balloon inflation at a position
along a vessel pathway where vessel constriction due to muscle spasms are
encountered, or to anchor the catheter at the target site.
These and other objects and features of the invention will become more
fully apparent when the following detailed description of the invention is
read in conjunction with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 shows a catheter device constructed according to one embodiment of
the invention;
FIG. 2 is an enlarged sectional view taken along line 2--2 of FIG. 1;
FIG. 3 shows the enlarged distal end section of the FIG. 2 catheter device
with the balloon in an inflated condition;
FIGS. 4-8 are enlarged sectional views of the distal end sections of
catheter devices constructed according to various alternative embodiments
of the invention;
FIG. 9 shows a portion of a small-vessel tortuous path in a target tissue;
FIG. 10 shows a branch junction region from FIG. 9, in which the path of
the catheter follows the larger-diameter of two branch vessels; and
FIG. 11 shows a branch junction region from FIG. 9, in which the path of
the catheter follows the smaller-diameter of two branch vessels.
DETAILED DESCRIPTION OF THE INVENTION
I. Catheter Device Construction
FIGS. 1-3 show a catheter device 10 constructed according to one embodiment
of the invention. Device 10 includes a catheter 12 composed of a flexible,
thin-walled tube 14 having an inner lumen 15 extending between proximal
and distal catheter end regions 16, 18, respectfully. The proximal
catheter end is provided with a syringe fitting 20 through which fluid can
be supplied to the catheter lumen through a port 22. The fitting also
includes an axially extending port 24 also communicating with the
catheter's inner lumen. Tube 14 preferably has an inner diameter of
approximately 15-60 mils and walls that are approximately 3-15 mils thick.
The total tube length is preferably between about 50-300 cm.
With reference now to FIGS. 2 and 3, the proximal end of the catheter is
provided with an inflatable balloon 26 which forms an intermediate section
of the distal end region of tube 14. The balloon is preferably about 0.5
to 2 cm in length, and has a wall section which can be inflated by fluid
supply through the catheter lumen, when the distal end of the tube is
blocked in a manner to be described below. The balloon wall section is
preferably formed integrally with the tube, according to known extrusion
methods for producing a thin walled-extruded tube with a more flexible
distal-end wall section. In particular, the balloon may be formed by
inflating the balloon section in a heated condition, then deflating when
the balloon wall section has cooled. Alternatively, the balloon may be
formed from a sleeve of elastomeric material, such as silicon rubber, and
attached at its opposite sleeve ends to relatively more rigid tube
sections.
Disposed in the distal end of the catheter tube is an annular plug or ring
28 defining an aperture 30 formed axially in the ring. The ring, which is
also referred to herein as means defining aperture 30, is positioned
downstream of (on the distal side of) the means communicating the catheter
lumen with the inflatable balloon. Specifically, the position of the
aperture is such that when the aperture is blocked, according to the
methods described below, fluid supplied through the catheter lumen is
forced into the balloon. In the present case, the means communicating the
lumen with the balloon is defined by the region of the lumen coextensive
with the inflatable balloon section, so that the ring may be positioned
anywhere distal to the balloon wall section in the catheter tube. The
diameter of the aperture is typically about 40-80% of the lumen diameter.
The ring may be made of a suitable metallic or nonmetallic material, and
can be attached to the catheter tube by heat shrinking, solvent bonding or
the like.
Disposed at the proximal margin of the balloon wall section is a stop 32 in
the form of an annular wedge preferably made of noncross-linked
polyethylene or silicon thermally formed onto the inside wall of tube 14.
As seen, the annular wedge shape of the stop provides a relatively smooth
transition with the lumen wall, on proceeding in a downstream (distal)
direction.
With continued reference to FIGS. 2 and 3, stop 32 and ring 28 support the
ends of a compressible coil 34 which extends approximately the length of
the balloon wall section, as shown. The coil, which is also referred to
herein as a compressible member, preferably has an outer coil diameter
roughly that of tube 14. As seen in FIG. 2, when the balloon is a deflated
condition, the coil expands to maintain the balloon wall section is a
substantially stretched condition. The coil also gives column strength to
the region of the catheter along the balloon wall section, and also
prevents the wall section from collapsing, i.e., the coil maintains the
diameter of the wall section substantially the same as that of the more
rigid tube sections on either side of the balloon.
The catheter device also includes an elongate, torqueable guide wire 36
which is constructed to extend through the catheter for axial sliding
therein. The length of the guide wire is typically at least about 10-50 cm
longer than the catheter, such that the distal end of the guide wire, seen
in FIGS. 2 and 3, can be extended at least several centimeters beyond the
distal end of the catheter, while allowing the proximal end of the wire to
be manipulated, such as by torquing, adjacent the proximal end of the
catheter. The proximal end of the wire is equipped with a handle or
torquing wheel 38 for applying torque to the wire during a catheter
operation.
The guide wire may have a variable or step diameter along its length,
typically including a larger-diameter, stiffer proximal region, and one or
more smaller-diameter, more flexible distal end regions, giving the wire
good torqueability in its more proximal region, and better flexibility and
maneuverability along its more distal region where the wire is advanced
along small-diameter tortuous pathways. Typical wire dimensions, for a
catheter having an lumen diameter of between about 20-50 mils, are a
proximal segment extending along all but the last 20-50 cm of wire and
having a diameter of between about 18-40 mils, and one or more reduced
diameter segments 20-50 cm in length having diameters of between about
8-18 mils.
In addition the distal end portion of the wire may have a substantially
constant taper, down to a final wire thickness of about 1-5 mils, for
greater distal-end flexibility. This tapered region is preferably encased
in a constant-diameter platinum coil, such as coil 40 seen in FIGS. 2 and
3. A guide wire having a relatively short, e.g., 1-5 cm tapered end
regions are described in U.S. Pat. No. 4,545,390. More recently, a guide
wire with a substantially longer distal end taper has been described in
coowned U.S. patent application for "Tapered Guide Wire and Method", Ser.
No. 043,642, filed Apr. 28, 1987.
Also as seen in FIGS. 2 and 3, the diameter of the distal end section of
the wire, including wire coil 40, is substantially less than that of
aperture 30, allowing a distal end portion of the wire to be moved freely
(with clearance) through the aperture. The guide wire terminates in a bent
tip 42 which can be oriented by torquing. The guide wire is preferably
made of stainless steel such as is commercially available from Wytech or
National Standard. The tapered tip may be made by a suitable technique,
such as by grinding. In the embodiment shown, guide wire 36 is 8-20 mils
at its proximal end and tapers down to a 2 mil distal tip over about a
10-20 cm length. Coil is made conventionally of tightly wound 3 mil
platinum, tungsten or other suitably radiopaque wire commercially
available, e.g., from California Fine Wire Company or Sigmund Cohn. This
coil preferably has an inner diameter of 7 mils and a length of
approximately 10-20 cm. The coil is attached to guide wire 12 by
appropriate technique, such as soldering or brazing.
The guide wire also includes a radial enlargement 44 which is carried
typically about 5-20 cm from the distal end of the wire. As seen best in
FIG. 3, the diameter of the enlargement is such as to block aperture 30,
when the wire is moved to place the enlargement against the upstream side
of ring 28. At the same time the larger-diameter opening formed in stop 32
allows the wire enlargement to pass through easily. The enlargement may be
formed, as shown, of one or more coil wrappings of the guide wire, or by
any other suitable method for forming a rigid or elastomeric annular
enlargement on a guide wire. It will be appreciated from the above that
the ring 28 in the catheter and enlargement 44 in the guide wire form
valve structure for blocking aperture 30, when the guide wire is moved to
place the enlargement against the ring.
In operation, the guide wire is placed in the catheter through port 24 in
fitting 20, and threaded through the catheter until the wire's distal end
extends from the distal end of the catheter, as shown in FIG. 1. During a
catheter placement operation, as will be described in Section II below, it
will be advantageous to operate the catheter in an uninflated condition
during some phases of operation, and in an inflated operation at other
times. To achieve balloon inflation, the guide wire is moved axially to
block aperture 30, and fluid is supplied through the lumen through port 22
in fitting 20, acting to fill and inflate the balloon. It is seen from
FIGS. 2 and 3 that as the balloon inflates, coil 34 becomes compressed, in
effect, resisting the tendency of the balloon to inflate. At all times,
the coil acts to keep the balloon wall section in a substantially
stretched condition.
To deflate the balloon, the guide wire is retracted, to unblock the
aperture and cause the fluid in the balloon to leak out the distal end of
the catheter. The tendency of the balloon to deflate is assisted by coil
34 which biases the balloon wall section toward its uninflated state seen
in FIG. 2. Alternatively, or in addition, the balloon can be deflated by
withdrawing fluid from the catheter through port 22.
As will be seen in section II below, the catheter device just described,
and those described below with reference to FIGS. 4-8, allow catheter
guidance and placement in a small-diameter, tortuous vessel pathway by a
combination of flow-directed and guide-wire directed branch vessel
selection. The specific embodiment just described has a number of
additional advantages: The wall section of the balloon has a relatively
high column strength and constant diameter, in the uninflated state, by
virtue of the compressible coil construction, which maintains the
uninflated wall section in a stretched condition. The coil further acts to
assist balloon deflation, when fluid is released or withdrawn from the
catheter. The aperture at the distal end of the catheter can be made
relatively large, allowing good flow of material injected at the target
site when the guide wire is withdrawn. Finally, the valve structure,
whereby the guide wire enlargement abuts the catheter ring when the valve
is closed, allows the catheter and guide wire to be advanced as a unit in
a downstream direction by advancing the guide wire distally. This method
of advancing the catheter device can be carried out with the balloon in
either an inflated or deflated condition.
FIGS. 4-8 illustrate distal end portions of additional embodiments of the
catheter device invention. These devices share many of the basic features
described above with respect to device 10, and illustrated in FIG. 1,
including a catheter which has an inner lumen which communicates with a
distal end balloon through communicating means, and having an aperture
disposed in the catheter distal to the means communicating the balloon and
lumen, such that with the aperture blocked, fluid supplied through the
lumen is forced into and inflated the balloon. The devices also each
include a guide wire which forms with the aperture in the corresponding
catheter, valve structure for blocking the aperture at one or more
selected wire positions.
FIG. 4 illustrates a catheter device 50 in which the catheter, indicated at
52, has an inflatable balloon 54 which is formed by an inflatable sleeve
56 secured at its opposite ends to a thin-walled, flexible catheter tube
58. The balloon sleeve may be formed of a thin polymer material, and
preferably an elastomeric, stretchable material, such as silicon or latex
rubber, or alternatively, a non-stretchable film material, such as
polyethylene. Attachment of the sleeve ends to the catheter tube is tube
by gluing, heat sealing, or the like, also according to known methods. The
advantage of an elastomeric sleeve is that it tends to remain flush with
the tube in an uninflated state, and also tends to resist balloon
inflation. Therefore, the balloon will tend to deflate itself when fluid
pressure in the tube is released, much as occurs in device 10 under the
action of coil 34.
Balloon 54 communicates with the catheter lumen through an opening 60
formed in the catheter tube. Distal to this opening is a ring 62, which
defines an aperture 64 in the catheter tube.
A guide wire 66 in the device is provided with a radial enlargement 68
which is dimensioned to block the aperture when the wire is moved to place
the enlargement against the upstream side of ring 62. This wire
enlargement thus forms with the ring valve structure for blocking the
catheter lumen downstream of opening 60, at a selected wire position. The
guide wire and its enlargement may have substantially the same
construction as guide wire 36 in device 10. The operation of device 50, in
balloon inflating and deflating operations, is substantially identical to
that of device 10, except of course that the length of the distal catheter
tube region remains fixed, and resistance to balloon inflation, if any, is
provided by stretching of the balloon sleeve, rather than by compression
of a coil in the tube.
FIG. 5 shows a similar type of catheter device 70 having a distal-end
balloon 72 which is attached to and extends from the distal end of the
catheter tube, indicated at 74. The balloon is formed of a membranous or
elastomeric sac having a distal opening 76 which is dimensioned to receive
the distal end of a guide wire 78 freely therethrough. The opening is
reinforced by a plug 80 whose inner bore with the same diameter as opening
76. This plug, which is preferably a flexible elastomeric material, may be
formed integrally with the balloon, or attached to the balloon as by
gluing. The opening and plug form a ring which defines a central aperture
81 in the catheter.
Guide wire 78 in the device is provided with a bolt-shaped annular
enlargement 84 whose distal "shaft" portion 84a is designed to be received
in aperture 81. The distal edge of the enlargement is somewhat tapered, as
indicated, to facilitate entry into the aperture. The outer "head" portion
84b of the enlargement is preferably dimensioned to seal the lumen of the
catheter tube, when the enlargement is positioned with the catheter tube.
The enlargement is an elastomeric member, and is attached to the body of
the guide wire, e.g., by heat shrinkage. The enlargement and aperture
formed in the distal end of the balloon collectively form valve structure
for use in inflating the balloon, as above.
In operation, the balloon is inflated by moving the guide wire in a forward
(distal) direction, to block aperture 81, and supplying fluid through the
lumen. Once the balloon fills, fluid pressure within the balloon acts to
maintain the enlargement against the distal end of the balloon within the
aperture, and the slight axial force originally applied to the wire to
insert the enlargement in the aperture can be released, allowing the
balloon to expand without axial stretching. To deflate the balloon, the
guide wire is retracted to draw enlargement 84 into the catheter tube,
allowing the fluid in the balloon to leak out through opening 76.
In FIG. 6, a catheter device 90 has a catheter 92 whose tube and distal
balloon construction is substantially the same as that of catheter 52 in
FIG. 4, where the balloon communicates with the catheter tube lumen
through an opening 94 in the catheter tube. Here, however, the aperture is
defined not by a ring supported within the catheter lumen, but by the
lumen itself, in the region between opening 94 and the distal end of the
catheter tube. This region or aperture is indicated generally at 96 in the
figure.
A guide wire 98 in the device has an elastomeric annular seal 100 which is
tapered on either side, as shown, and whose outermost rim 102 is
dimensioned to form a seal with the inner lumen of the catheter tube. With
the seal positioned within the aperture of the catheter, i.e., between
opening 94 and the distal end of the catheter tube (solid lines in the
figure), the seal and aperture form valve structure for blocking the
aperture. At this position, supplying fluid through the lumen inflates the
balloon. With the guide wire moved slightly in a proximal or upstream
direction, to place the seal at the position shown at 104, the lumen
remains sealed, but fluid can leak from the balloon, for deflating the
balloon. When the catheter is positioned at the target site, the guide
wire can be moved proximally or downstream somewhat, to place the seal at
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