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Claims  |
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It is claimed:
1. Apparatus for use in producing vaso-occlusion at a selected site in a
body vessel comprising
a catheter having proximal and distal ends and an interior lumen extending
therebetween, and adapted for placement of its distal end adjacent such
selected site,
a vaso-occlusion wire extendable from a relaxed condition capable of
assuming a convoluted condition, to an extended, linear condition in which
the wire can be advanced through said lumen,
a pusher which is controllable from the proximal catheter end to advance
said wire, with such in its extended condition, through said catheter by
contact between confronting ends of the pusher and wire,
a radial enlargement carried on one of such confronting ends, and
expandable clamping structure associated with the other of such
confronting ends for movement between a closed condition produced by
contact of the structure with the catheter lumen, in which the clamping
structure is effective to hold the radial enlargement in clamping
structure is expanded to release the radial enlargement, and
release means in said catheter, adjacent its distal end, for releasing the
clamping structure from its closed to its open condition when a selected
portion of the wire has been advanced beyond the distal catheter end.
2. The apparatus of claim 1, wherein said radial enlargement is carried on
said wire, and said clamping structure is associated with said pusher.
3. The apparatus of claim 1, wherein said clamping structure is an
expandable coil for expansion between a closed, more coiled condition
produced by contact of the coil with the catheter lumen, in which the coil
is effective to hold the radial enlargement in clamped engagement, and an
open, less coiled condition produced by interaction of the jaws with said
release means, in which said coil is expanded to release the axial
enlargement.
4. The apparatus of claim 3, wherein said radial enlargement is carried on
said wire, and said coil is associated with said pusher.
5. The apparatus of claim 3, wherein said radial enlargement is carried on
said pusher, and said coil is associated with said wire.
6. The apparatus of claim 1, wherein said release means is defined by the
distal-end of said catheter.
7. The apparatus of claim 1, wherein said release means includes a radially
enlarged segment in said catheter lumen, adjacent the catheter's distal
end.
8. The apparatus of claim 1, wherein said wire includes an elongate coil
whose opposite ends are connected by a substantially inelastic thread.
9. The apparatus of claim 1, for use in guiding the catheter through a
branched vessel path by flow-directed movement of the catheter's distal
end, wherein said wire includes flexible distal-end structure which, when
advanced beyond the distal end of the catheter, is adapted to open to
provide increased area of contact with blood flowing in a vessel.
10. The apparatus of claim 9, wherein said wire includes an elongate coil
whose opposite ends are connected by a substantially inelastic thread.
11. The apparatus of claim 1, for use in guiding the catheter through a
branched vessel path by wire-directed movement of the catheter's distal
end, wherein said wire is torqueable and includes a distal end region
which assumes a bent configuration when the end region is advanced beyond
the distal end of the catheter, and said clamping structure is effective
to transmit torque between said pusher and said wire, with such in the
catheter lumen.
12. The apparatus of claim 11, wherein said wire includes an elongate coil
whose opposite ends are connected by a torqueable, substantially inelastic
band.
13. A pusher-and-wire assembly for use with a catheter having proximal and
distal ends and an interior lumen extending therebetween and which is
adapted for placement at a selected vessel site, comprising
a vaso-occlusion wire extendable from a relaxed condition capable of
assuming a convoluted shape, to an extended, linear condition in which the
wire can be advanced through the lumen of such catheter,
a pusher which is operable from the proximal catheter end to advance said
wire axially, with such in its extended condition, through said catheter
by contact between confronting ends of the wire and pusher,
a radial enlargement carried on one of such confronting ends, and
expandable clamping structure associated with the other of such confronting
ends adapted for movement between a closed condition produced by contact
of the clamping structure with the catheter lumen, in which the structure
is effective to hold the radial enlargement in clamped engagement, and an
open condition produced by expansion of the structure, in which the
enlargement is axially releasable from the structure.
14. The assembly of claim 13, wherein said clamping structure includes
expandable jaws adapted for movement between a relaxed, open condition and
a adapted for movement between a relaxed, open condition and a closed
condition produced by contact of the jaws with the catheter lumen.
15. The assembly of claim 14, wherein said radial enlargement is carried on
said wire, and said jaws are associated with said pusher.
16. The assembly of claim 14, wherein said clamping structure includes an
expandable coil adapted for expansion between a closed, more coiled
condition produced by contact of the coil with the catheter lumen, and an
open, less coiled condition, in which said coil is expanded to release the
radial enlargement.
17. The assembly of claim 16, wherein said radial enlargement is carried on
said wire, and said coil is associated with said pusher.
18. The assembly of claim 16, wherein said radial enlargement is carried on
said pusher, and said coil is associated with said wire.
19. The assembly of claim 13, wherein said wire includes an elongate coil
whose opposite ends are connected by a substantially inelastic thread.
20. The assembly of claim 13, for use in guiding a catheter through a
branched vessel path by flow-directed movement of the catheter's distal
end, wherein said wire includes flexible distal-end structure which, when
advanced beyond the distal end of the catheter, is adapted to open to
provide increased area of contact with blood flowing in a vessel.
21. The assembly of claim 20, wherein said wire includes an elongate coil
whose opposite ends are connected by a substantially inelastic thread.
22. The assembly of claim 13 for use in guiding the catheter through a
branched vessel path by wire-directed movement of the catheter's distal
end, wherein said wire is torqueable and includes a distal end region
which assumes a bent configuration when the end region is advanced beyond
the distal end of the catheter, and said clamping structure is effective
to transmit torque between said pusher and said wire, with such in the
catheter lumen.
23. The assembly of claim 22, wherein said wire includes an elongate coil
whose opposite ends are connected by a torqueable, substantially inelastic
band.
24. A vaso-occlusion wire for use with a catheter having proximal and
distal ends and an interior lumen extending therebetween and which is
adapted for placement at a selected vessel site, and a pusher which is
operable from the proximal catheter end for radial movement through the
catheter lumen to a release position, said pusher including a clamping
structure, comprising
an extendable, torqueable wire portion which is extendable from a relaxed,
convoluted condition, to an extended, linear condition in which the wire
can be advanced through the lumen of such catheter, and
a radial enlargement carried at one end of the wire portion for torqueable
clamping engagement with and release from the clamping structure in the
pusher.
25. A method for placing a vaso-occlusion wire at a selected site in a
vessel, where the catheter is guided through a branched vessel path by
flow-directed movement of the catheter's distal end, comprising
guiding the distal end of a catheter to such site, by
advancing within the catheter a vaso-occlusion wire which is extendable
from a relaxed, convoluted condition, to an extended, linear condition,
where said wire includes a flexible distal-end structure which, when
advanced beyond the distal end of the catheter, is adapted to open to
provide increased area of contact with blood flowing in a vessel, and said
advancing includes (a) advancing the wire distally, to advance said
segment beyond the distal end of the catheter, when it is desired to guide
the catheter into a vessel branch having greater fluid flow at a branch
point, and (b) retracting the wire proximally, to draw said segment within
the distal end of the catheter, when it desired to guide the catheter away
form a vessel branch having greater fluid flow at a branch point, and
during said advancing, maintaining the wire in an axially clamped condition
in which the wire can be moved axially in both directions within the
catheter, until a selected portion of the wire has been advanced beyond
the distal end of the catheter, at which point the wire is released from
its clamped condition.
26. A vaso-occlusion wire for use with a catheter having proximal and
distal ends and an interior lumen extending therebetween and which is
adapted for placement at a selected vessel site, and a pusher which is
operable from the proximal catheter end for radial movement through the
catheter lumen to a release position, said pusher including a clamp
structure, comprising
an extendable, wire portion which is extendable rom a relaxed, convoluted
condition, to an extended, linear condition in which the wire can be
advanced through the lumen of such catheter, said extendable portion
including an elongate segment whose opposite ends are connected by a
substantially inelastic member, and
a radial enlargement carried at one end of the wire portion for clamping
engagement with and release form the clamping structure in the pusher.
27. The wire of claim 26, wherein said member is a torqueable band adapted
to transmit torque from said radial enlargement along the length of the
extendable portion.
28. A vaso-occlusion wire for use with a catheter having proximal and
distal ends and an interior lumen extending therebetween and which is
adapted for placement at a selected vessel site, and a pusher which is
operable from the proximal catheter end for radial movement through the
catheter lumen to a release position, said pusher including a clamp
structure, comprising
an extendable, wire portion which is extendable from a relaxed, convoluted
condition, to an extended, linear condition in which the wire can be
advanced through the lumen of such catheter, said wire including flexible,
distal-end structure which, when advanced beyond the distal end of the
catheter, is adapted to open to provide increased area of contact with
blood flowing through a vessel, and
a radial enlargement carried at one end of the wire portion for clamping
engagement with and release form the clamping structure in the pusher.
29. A method for placing a vaso-occlusion wire at a selected site in a
vessel, where the catheter is to be guided through a branched vessel path
by wire-directed movement of the catheter's distal end, comprising
guiding the distal end of a catheter to such site, by advancing within the
catheter a vaso-occlusion wire which is extendable from a relaxed,
convoluted condition, to an extended, linear condition, where said wire
includes a distal-end segment which assumes a bent configuration when the
end region is advanced beyond the distal end of the catheter, and said
wire can be torqued remotely as it is advanced within the catheter, and
said advancing includes (a) advancing the wire distally, to advance said
segment beyond distal end of the catheter, when it is desired to guide the
catheter into one of two vessels at a branch point, (b) torquing the wire
to orient the bent segment of the wire in the direction of the one vessel
at the branch point, and (c) advancing the wire distally to guide the
catheter into the one vessel, and
during the said advancing, maintaining the wire in an axially clamped
condition in which the wire can be moved axial in both directions within
the catheter, until a selected portion of the wire has been advanced
beyond the distal end of the catheter, at which point the wire is released
from its clamped condition. |
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Claims |
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Description |
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FIELD OF THE INVENTION
The present invention relates to a retractable-coil catheter device, a
pusher-and-coil assembly, a vaso-occlusion coil, and to a method for
placing a vaso-occlusion coil at a selected site in a vessel.
BACKGROUND OF THE INVENTION
Vaso-occlusion wires are used in treating vascular conditions in which it
is desired to occlude a region of a vessel or an aneurism within a vessel.
The wire is introduced by first positioning a catheter at the selected
site to be occluded, then advancing the wire through the catheter and into
the site. The wire itself is typically a soft wire coil which can assume a
linear condition for advancement though the catheter, and assume a
convoluted configuration designed to "fill" the vessel or aneurism into
which the coil is introduced, as described for example in U.S. Pat. No.
4,994,069.
Commonly, the vaso-occlusion wire must be placed at a remote, small-vessel
site which can be accessed only through a tortuous vessel path involving
multiple vessel branches, sharp turns at a vessel branch point, and/or
small-diameter vessels, e.g., less than 2-5 mm. Such sites can be accessed
only with a flexible, small-diameter catheter, e.g., a polyethylene-tube
catheter having a distal-end inner diameter of 10-30 mils. Such a catheter
is typically guided through a tortuous vessel by a guidewire having a bent
tip whose direction can be controlled, to steer the catheter along a
selected path.
After the catheter has been placed at the intended site, the guidewire is
removed and the catheter is loaded with a vaso-occlusion wire, which is
then advanced through the catheter with a pusher. When the wire is
advanced beyond the end of catheter at the vaso-occlusion site, it assumes
its convoluted shape designed to fill the vessel space into which it is
placed.
One limitation of the above vaso-occlusion method just described is the
difficulty in controlling the orientation and position of the wire in the
vessel, or aneurism, after it is ejected from the catheter. For example,
the wire may fail to anchor itself firmly in the vessel, and thus be
carried by blood flow to a site downstream of the intended vaso-occlusion
site. In addition, the wire may improperly orient itself at the site,
producing incomplete vaso-occlusion. In either case, the vaso-occlusion
procedure may be only partially effective.
SUMMARY OF THE INVENTION
It is a general object of the present invention to provide an improved
method and catheter apparatus for placing a vaso-occlusion coil at a
selected vessel site.
The invention includes, in one aspect, catheter apparatus having a catheter
designed for placement at a selected vessel site, a vaso-occlusion wire
which is extendable from a relaxed, convoluted condition, to an extended,
linear condition in which the wire can be advanced through said lumen, and
a pusher designed for advancing the wire through the catheter. Confronting
ends of the pusher and wire are provided with clamping structure for
holding the wire in clamped engagement with the pusher, as the wire is
advanced through the catheter lumen. The clamped condition of the
structure is released when a selected portion of the wire has been
advanced beyond the distal catheter end, to release the wire into the
vessel site.
In one embodiment, the clamping structure includes an axial enlargement
carried on the wire, and expandable jaws associated with pusher, for
movement between a closed condition produced by contact of the jaws with
the catheter lumen, in which the jaws are effective to hold the axial
enlargement in clamped engagement, and an open condition produced by
expansion of the jaws, to release the axial enlargement in the wire.
The catheter apparatus may be designed for flow-directed or wire-directed
catheter guidance to the site. For flow-directed guidance, the wire
additionally includes a distal-end segment which is expandable, when
advanced beyond the distal end of the catheter, to enhance movement of the
segment in the direction of highest fluid flow. For wire-directed
guidance, the wire additionally includes a distal-end segment which
assumes a bent configuration when the end region is advanced beyond the
distal end of the catheter. The clamping structure in this embodiment is
effective to transmit torque between the pusher and the wire, for
orienting the bent wire tip during catheter placement.
In another aspect, the invention includes a pusher-and-wire assembly for
use with a catheter which can be placed at a selected vessel site. The
assembly includes a vaso-occlusion wire extendable from a relaxed,
convoluted condition, to an extended, linear condition in which the wire
can be advanced through the lumen of the catheter, and a pusher which is
operable from the proximal catheter end to advance the wire axially, with
such in its extended condition, through the catheter by contact between
confronting ends of the pusher and wire. Also included in the invention is
a vaso-occlusion wire device for use with a catheter and pusher of the
types described above.
In another aspect, the invention includes a method for placing a
vaso-occlusion wire at a selected site in a vessel. The method includes
the steps of guiding the distal end of a catheter to such site, advancing
through the catheter, and a vaso-occlusion wire which is extendable from a
relaxed, convoluted condition, to an extended, linear condition. During
wire advancing, the wire is maintained in an axially clamped condition in
which the coil can be moved axially in both directions within the
catheter, until a selected portion of the wire has been advanced beyond
the distal end of the catheter, at which point the wire is released from
its clamped condition.
The method may be adapted for use in guiding the catheter to the selected
vaso-occlusion site through a branched vessel path by flow-directed or
wire-directed movement of the catheter's distal end, employing one of the
modified wires described above.
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 apparatus constructed according to a general
embodiment of the invention;
FIG. 2 is an enlarged, fragmentary view of a wire-and-pusher assembly taken
generally along line 2--2 in FIG. 1;
FIG. 3 is an enlarged, fragmentary view of a second embodiment of a
wire-and-pusher assembly in the invention;
FIG. 4 illustrates one mechanism of wire release in the apparatus of the
invention;
FIG. 5 illustrates a second mechanism of wire release in another embodiment
of the invention;
FIG. 6 illustrates another embodiment of a pusher-and-wire assembly in the
invention;
FIG. 7 illustrates the mechanism of wire release in the FIG. 6 assembly;
FIGS. 8A and 8B illustrate the method of wire placement in a vessel, in
accordance with the method of the invention;
FIGS. 9A-9D illustrate steps in a method of wire retrieval or
repositioning, in accordance with a further aspect of the method of the
invention;
FIGS. 10A and 10B illustrate a vaso-occlusive wire constructed, according
to another embodiment of the invention, for use in flow-directed catheter
placement, at retracted (10A) and extended (10B) positions in a catheter;
FIG. 11 illustrates the method of flow-directed guidance employing the FIG.
10 wire;
FIGS. 12A and 12B illustrate a vaso-occlusive wire constructed, according
to another embodiment of the invention, for use in wire-directed catheter
placement, at retracted (12A) and extended (12B) positions in a catheter;
FIG. 13 shows modified clamping structures for use in the wire construction
shown in FIG. 12;
FIG. 14 is a cross-sectional view taken along line 14--14 in FIG. 13;
FIGS. 15A and 15B show side and sectional views of one alternative clamping
structure capable of transmitting torque from a pusher to a wire;
FIGS. 16A and 16B show side and sectional views of another alternative
clamping structure capable of transmitting torque from a pusher to a wire;
and
FIG. 17 illustrates the method of wire-directed guidance employing the FIG.
12 wire.
DETAILED DESCRIPTION OF THE INVENTION
Catheter Apparatus
FIG. 1 shows a vaso-occlusion catheter device, or apparatus 10 constructed
according to the present invention. The device generally includes a
catheter 12 formed of an elongate tubular member 14 having proximal and
distal ends 15, 16, respectively. The tubular member is preferably between
about 50-300 cm in length, typically between about 100-200 cm in length.
An inner lumen 18 (FIGS. 2 and 3) extends between the two ends.
The catheter is designed conventionally for accessing a vessel site at
which vaso-occlusion is desired. Typically, the vessel site is within a
small-diameter vessel having 2-5 mm lumen diameter, and is accessible by
way of a tortuous vessel path which may involve sharp vessel turns and
multiple vessel branches. For accessing such vessel sites, the catheter
preferably has a small-diameter, flexible-tube construction, with a lumen
diameter of less than about 40 mil, and preferably between about 12-30
mil. Catheters of this type are commercially available, for example, for
accessing deep brain vascular sites.
Although not shown in FIG. 1, the catheter device may include a guidewire
useable with the catheter to guide the distal catheter end toward the
intended vaso-occlusion site. Guidewires of this type are commercially
available, and generally include an elongate wire having a tapered,
wire-wound distal end region which is adapted to be threaded through a
tortuous vessel path, with the catheter being moved axially along the
advanced guidewire. Once the catheter has been guided to the selected
vaso-occlusion site, the guidewire can be removed from the catheter.
Also included in the apparatus is a vaso-occlusion wire 20 which is
extendable from a relaxed, convoluted condition shown, for example, in
FIGS. 8A and 8B, to an extended, linear condition, shown in FIG. 1, in
which the wire can be advanced axially through the catheter lumen. The
wire is moved through the catheter by a pusher 22 in the apparatus which
is operable from the proximal end of the catheter. The construction of the
wire and pusher are detailed below.
According to one feature of the invention, the wire and pusher are held
together in clamped engagement at their confronting ends in the catheter
by clamping structure or means 24 associated with the wire and pusher, as
will be detailed below. The clamping engagement of the wire and pusher are
designed to be released, in accordance with the invention, by catheter
structure or means adjacent the catheter's distal end. The clamping and
release structure are also detailed below.
FIG. 2 is an enlarged view of the catheter apparatus, taken generally along
the region 2--2 in FIG. 1, and showing details of clamping structure 24
associated with confronting ends 26, 28, of pusher 22 and wire 20,
respectively. The clamping structure in the FIG. 2 embodiment includes a
jaw-like clamp 30 forming the distal end portion of the pusher, and a
radial enlargement 32 forming the proximal end portion of the wire. The
clamp has a pair of opposed jaws 34, 36 which are expandable between a
closed condition produced by contact of the jaws with the catheter lumen,
as shown in FIG. 2, and an open condition in which the jaws are in a
relaxed, somewhat expanded condition, shown in FIG. 4. The radial
enlargement in the wire is dimensioned for positive clamping by the jaws,
with such in their closed condition (FIG. 2) and for release from the
jaws, in an axial direction, with the jaws in their open condition (FIG.
4).
In one general embodiment, the extendable portion of wire 20 takes the form
of a coil, such as indicated at 38 in FIGS. 2 and 4, formed by wrappings
or windings of a fine wire thread 40, preferably 0.002 mils to 0.006 mils
platinum, tungsten, or gold thread which is available, for example, from
California Fine Wire Company (Grover City, Calif.). The windings are
preferably made by wrapping the thread on a spinning mandrel, according to
known wire-manufacturing methods. The wire advance on a mandrel is
adjusted to produce a single-layer wire with a minimum helical pitch,
i.e., in which the windings are close packed. Typically, the mandrel has a
diameter of between 5-25 mils (1/1000 inch), yielding a wire whose outer
diameter is between about 10-30 mils. The soft, flexible wire produced on
the mandrel is cut to desired lengths after removal from the mandrel. For
wires intended for use in vessels with diameters of about 2 mm and
smaller, the wire has a preferred length of about 3-6 cm. For vessels in
the 2-6 mm range, wire lengths of between about 5-10 cm are preferred.
The relaxed, convoluted shape of the coil is achieved by shaping the wire,
i.e., by wrapping the wire about a larger-diameter mandrel to form a
helical shape, e.g., having a helical diameter between 2-6 mm,
respectively. The wire may be further deformed to contain irregularities
in the helical winding, such that the wire adopts a folded, convoluted
conformation in a relaxed condition, as illustrated in FIG. 8A. The
irregularities are preferably made by deforming, as by twisting, the wire
in the region of desired bends with the wire on the helical winding
mandrel.
After shaping, the coil is treated at about 800.degree. F. for 24 hours for
memory retention after it is shaped. The memory in the coil is effective
to return the wire from a stretched, linear condition in which it is
advanced through a catheter to a randomly oriented, spaced-filling relaxed
condition as the wire is released from the catheter. The high memory in
the wire is achieved, in part, by the overall length of the thread used in
forming the coil, i.e., the high ratio of thread length change in wire
shape.
Alternatively, the extendable portion of the vaso-occlusion wire may be
formed from a flexible, preshaped polymer tube or rod. The convoluted
shape of the tube or rod may be achieved by a combination of a helical
winding and/or irregularities which are imparted during heat treatment, or
by shaping the wire as it is extruded, before cooling, or by injection
molding. Suitable polymers for use in preparing this type of wire include
any biocompatible polymer such as polyethylene, polyurethane,
polypropylene, an the like, which are capable (by their inherent memory)
of substantially reversible shape-retention between extended and
preformed, relaxed conditions.
With continued reference to FIG. 2, the proximal end of the wire (the end
confronting the pusher in the catheter) includes a stem 42 which connects
the coiled portion of the wire to radial enlargement 32. The stem and
radial enlargement may be formed by extrusion or molding a suitable
biocompatible polymer material. The stem is attached to the coil by an
adhesive or solder. Alternatively, where the extendable portion of the
wire is formed of a polymer tube or rod, the stem and radial enlargement
can be formed integrally with the extendable portion.
Pusher 22 shown in FIG. 2 is formed of a conventional guidewire 44 which is
designed for axial movement within the catheter, by manipulation of the
guidewire's proximal end at the proximal end of the catheter. The
guidewire has a typical diameter of between about 8-18 mils, for use with
a catheter having a lumen diameter of between about 15-30 mils,
respectively. Although not shown here, the guidewire may have a more
flexible distal end region formed of a reduced diameter taper in the
distal region of the guidewire, and this tapered region may be reinforced,
for greater column strength, by a wire wrapping, according to known
guidewire construction.
The clamp in the pusher wire may be formed from a metal or polymeric rod
having suitable shape-retention and resilience properties. Polymer rods
suitable for use in forming the clamp include polyethylene, Teflon.TM.,
polypropylene, and polycarbonate. The rod typically has a diameter
approximately that of the guidewire, e.g., between 8-18, and a length
between about 0.5-2 cm. To form the clamp, the rod is cut axially through
a center plane along a major portion of the rod length. This cut forms two
hemicylindrical rod sections which will form the jaws of the clamp. These
jaws are formed by shaping the rod sections about a shaping member having
a cross-sectional shape similar to that of the region between the jaws in
FIG. 4. Shaping of the rod sections over the shaping member may be
accomplished by forcing the rod sections over the shaping member, in the
case of metal jaw members, or by heat-shaping the rod sections over the
shaping member, in the case of a heat-shapable polymer material. The
shaping is preferably carried out to form the jaws in their open
positions, such as illustrated in FIG. 4, requiring a slight compressive
force on the jaws to place the clamp in its closed condition. The clamp is
attached to the distal end of the guidewire by a solder or adhesive
attachment 45, to form the pusher.
It will be appreciated that the clamp may have three of more jaws which are
movable toward and away from the axis of the clamp, between a relaxed,
open condition, and a compressed clamping condition. A multi-jaw clamp of
this type can be formed as above, where a suitable rod is cut axially into
three of more rod sections, and the sections are shaped to form the jaws
of the clamp. A multi-jaw clamp has an advantage over the two-jaw clamp
shown in FIGS. 2 and 4, in that the stem carrying the radial enlargement
in the wire is positively oriented in an axial direction during axial
movement of the wire through an beyond the distal end of the wire.
The pusher and wire described above with reference to FIGS. 1 and 2 form,
collectively, a pusher-and-wire assembly 46 which forms another aspect of
the invention. The assembly is designed for use with a catheter, such as
catheter 12, in placing a vaso-occlusion wire at a selected vascular site,
and at a selected configuration at the site.
FIG. 3 illustrates a clamping structure 50 similar to structure 24 shown in
FIG. 2, but in which a clamp 52 forms the proximal end of a vaso-occlusive
wire 54, and a radial enlargement 56 captured in the clamp is formed at
the distal end of a pusher 58. The clamp may be formed as described above,
for attachment to one end of a coil. As shown the radial enlargement is
preferably formed at the end of a rod segment 60 having a reduced-diameter
stem 62 and a base 64 attached, at a solder or adhesive attachment 65, to
the distal end of a guidewire 66. The clamp structure shown in FIG. 3
functions substantially identically to the structure shown in FIG. 2, as
will be seen. The pusher and wire in this embodiment form a
pusher-and-wire assembly 68 for use with a catheter, such as catheter 67,
for placement of a vaso-occlusion wire at a selected vascular site.
FIG. 4 illustrates the distal end region of catheter 12 shown in FIGS. 1,
and 2, illustrating the clamping structure in the apparatus in a release
condition. In this embodiment, clamp 30 is retained in its clamped
condition by contact with the inner lumen of catheter 12, and allowed to
expand to its open, release condition when the pusher is moved axially to
a position in which the clamp jaws are just beyond the distal catheter
end. As seen and described above, jaws 34, 36 in the clamp are spread
sufficiently in the open clamp condition to allow radial enlargement 32 to
escape, in a axial direction, from the clamp, thus releasing the wire from
the pusher.
In this embodiment, the distal end of the catheter acts as means for
releasing the clamped engagement of the wire to the pusher, as the clamp
has been advanced beyond the distal catheter end. The catheter distal end
plays a similar role in releasing the clamped engagement of wire and
pusher in the FIG. 3 embodiment, when the clamp associated with the wire
is advanced beyond the distal end of the catheter.
FIG. 5 illustrates clamp release means in a catheter apparatus 70 like that
described above, but having a catheter 72 whose distal end region contains
a radially enlarged segment 74. The greater lumen wall diameter in segment
74 is designed allow expansion of jaws 76, 78 in a pusher clamp 80, as
indicated, to allow axial release of a radial enlargement 82 forming one
end of a wire 84, for wire release. The pusher and wire are constructed as
described above with respect to FIG. 2. In this embodiment, the enlarged
catheter segment serves as the release means in the apparatus for
releasing the clamped engagement of the pusher to the wire. It is noted
that the clamping structure shown in FIG. 3 would not be suitable for use
in the FIG. 5 present release means, since the wire in the FIG. 3
embodiment would be released from the pusher, but not from the catheter by
positioning the clamp in the enlarged catheter segment.
FIGS. 6 and 7 illustrate a second general type of clamp structure for
clamping a vaso-occlusive wire axially to the confronting end of a pusher
in a catheter. The figures show the distal end region of a pusher 86 and
the confronting, proximal end of a vaso-occlusive wire 88 which is clamped
to the pusher. The pusher in this embodiment has a coiled-loop clamp 89
formed by a helically looped segment 90. The loop is constructed to
assume, in a relaxed condition, the expanded loop configuration shown in
FIG. 7 in which the center region 92 of the segment loop is large enough
to allow axial escape of a radial enlargement 94 forming the confronting
end of wire 88. When the loop is disposed within a catheter, such as the
one indicated at 93, its more tightly coiled configuration serves to
capture the wire's axial enlargement as shown in FIG. 6.
Wire 88 in the just-described clamping structure may have substantially the
same construction as described for wire 20 in apparatus 10. Pusher 86 is
formed by joining segment 90 to a standard guidewire 96, at a solder
adhesive attachment 97. The segment may be formed from a polymer rod whose
coiled region is reduced in diameter and shaped by heating, or which is
formed by extrusion with a reduced-diameter end region and shaped in the
desired helical loop under heated conditions. The pusher and wire form a
pusher-and-wire assembly 99.
Although not shown here, the clamping structure shown in FIGS. 6 and 7 can
be modified so that the coiled-loop clamp is carried on the vaso-occlusive
wire, and the radial enlargement is carried on the pusher, analogous to
the configuration shown in FIG. 3. In this embodiment, the wire may be
formed from a polymer rod or tube, with the extendable portion of the wire
having the desired convolutions in the relaxed state, and a proximal end
segment of the wire having a coiled loop which is expandable between a
reduced-diameter, clamping condition, within the catheter, and a relaxed,
release condition outside the lumen of the catheter.
In either configuration, the distal end 95 of catheter 93 provides means
for releasing the clamped engagement of the of the wire to the pusher, as
the clamp is advanced beyond the distal catheter end.
Wire-Placement Method
The operation of the apparatus, for use in placing a vaso-occlusion wire at
a selected site in the vascular system, will be described with reference
to FIGS. 8 and 9. In a typical operation, the vaso-occlusion site is
accessible by a tortuous, small-vessel path which may include multiple
vessel turns or bends, and one or more vessel branches. The catheter is
guided to such a site, conventionally, by the use of a catheter and
guidewire, where the guidewire is used for steering along the path, and
the catheter is periodically advanced along the guidewire. The
vaso-occlusion site may be an aneurism which is to be blocked, or a region
in a small vessel which it is desired to occlude.
After the catheter has been guided to the selected site, and the guidewire
removed, the extended vaso-occlusion wire and pusher are inserted into the
proximal end of the catheter, with the wire clamped to the pusher's
clamping structure. In the embodiment shown in FIG. 2, the extended wire
is first inserted into the catheter with only the radial enlargement at
the wire's proximal end showing. The pusher clamp is placed over the
enlargement and the clamp and enlargement are then pushed into the
catheter, compressing the clamp jaws to their clamping condition. The
pusher is now advanced axially along the catheter, pushing the extending
vaso-occlusion wire toward the selected vascular site.
FIGS. 8A and 8B show the distal end of a catheter 100 placed adjacent a
selected occlusion site 102 within a small-diameter vessel 104. FIG. 8A
shows the configuration of a wire 106 as it is advanced out of the
catheter into the vessel, illustrating the convoluted, relaxed state which
the wire assumes as it is released from the catheter. When the extended
portion of the wire has been released, but before the wire is unclamped
from the pusher, the user can view the position and configuration of the
wire in the vessel, e.g., by fluoroscopy or angiography. If wire placement
is not correct, or the wire has not assumed a desired space filling
configuration, the user can adjust the wire position by movement of the
catheter in one direction or another.
When the desired position and orientation of the wire have been achieved,
the user now advances a pusher 108 slightly to a clamp-release position,
to release the wire from the catheter and pusher clamp 110, as illustrated
in FIG. 8B. The catheter and pusher can now be retracted from the site,
leaving the vaso-occlusion wire in place.
FIGS. 9A-9D illustrate how the apparatus illustrated in FIGS. 8A and 8B can
be used to adjust the position or orientation of vaso-occlusion wire 106,
after deposition of wire at a vaso-occlusion site 114 in a vessel 116, or
to retrieve a wire from a vessel site. In FIG. 9A, the wire is shown in a
relaxed convoluted configuration, but where the lower portion of the
vessel is substantially unblocked by the wire, with the wire wedged
between opposite side walls of the vessel. As a first step in the
operation, the catheter and pusher, with the jaws in an open condition,
are advanced to place the jaws over a section of the wire, as indicated in
FIG. 9B.
In the second step, the pusher is retracted into the catheter, to close the
jaws of the clamp, and thereby clamp a portion of the wire to the pusher.
The catheter and pusher can now be moved as a unit, either to adjust the
position and orientation of the wire, as shown in FIG. 9C, or to retract
the wire from the site. Finally, when a selected coil position and
orientation are achieved, the pusher is advanced to an open-clamp
position, releasing the wire from the catheter, illustrated in FIG. 9D.
Although the operation of the apparatus, in a wire-placement procedure, has
been described with respect to the apparatus described with respect to
FIGS. 1, 2, and 4, it will be appreciated how the procedure can be carried
out in a similar fashion by | | |
