Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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NTERING BALLOON STRUCTlJRE FOR TRANSLUMINAL ANG~OPLAS~Y CATHETER
BACKGROUND OF THE INVENTION
This invention relates to angioplasty catheters, and
more particularly to percutaneous transluminal laser angioplastY
catheters.
The treatment of occlusions, in arteries and blood
vessels in general, using an angioplasty catheter equipped with
an inflatable balloon at its distal tip, is well know. A more
recent technique involves providing an optical fiber in such a
catheter, and extending the distal end of the fiber slightly
beyond the distal tip of the catheter, whereby laser energy
generated at the proximal end of the fiber is transmitted to an
occlusion to be treated. For a further explanation o~ this
technique, reference is made to U.S. Patent No. 4,669,465 and
U.S. Patent No. 4,781,185 both assigned to the assignee o~ this
patent. An important requirement in using this technique is the
proper positioning and orientation of the catheter distal tip.
Precise positioning is essential to ensure that laser energy from
the optical fiber is directed away from the arterial wall.
Improper aiming can result in wall damage or even rupture to the
artery.
Apparatus for positioning a catheter distal tip is
known, although not necessarily in connection with transmission
of laser energy in the catheter. For example, U.S. Patent No.
4,545,390 to Leary granted October 8, 1985 shows a guide wire
with a helical spring is flexible and can be benk into a curve,
whereupon insertion can be guided by rotation of the guide wire
at the proximal end. U.S. Patent No. 4,033,331 to Guss et al
granted July 5, 1977 shows a catheter having a bend at its distal
end,
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and a contour wire which can be inserted varying amounts to
gradually straiyhten the bend. Somewhat related subject matter
is disclosed in u. S. Patent No. 4,150,676 to Jackson yranted
April 24, 197~. An ~ndotracheal tube disclosed by Jackson has an
inflatable balloon cuff at its distal end. ~ filament in a lumen
runs the length of the tube, and can be pulled to increase the
curvature at the distal end. While each of the devices disclosed
in these patents is perhaps suitable for its particular
environment, the paten~s fail to adequately address the need for
the precise catheter tip positioning required in laser enhanced
angioplasty catheters.
Therefore, it is an object of the present invention to
provide a means for accurately establishing the position and
orientation o~ the distal tip of a laser angioplasty catheter
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Another object of the invention is to provide a balloon
near the tip of an angioplasty catheter, which balloon is
particularly well adapted for centering the catheter distal tip
within an artery.
Yet another object of the invention is to provide a
catheter balloon adapted for orienting the distal tip of the
catheter in response to balloon dilation.
SUMMARY OF THE INVENTION
To achieve these and other objects, there is provided a
catheter balloon for attachment in surrounding relation to an
angioplasty catheter. The balloon includes an elongate tubular
member formed of a pliable material, including coaxial proximal
and distal end mounting segments for substantially fluid-tight
attachment of said tubular member to a length of pliable catheter
tubing extended through the tubular member. The balloon includes
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an elongate medial seyment bekween an~ coaxial with the end
mounting segments. The medial segment has a substantially larger
diameter than the diameter of the end mounting segments, and is
collapsible to an effective ~iameter slightly larger than the end
mountin~ segment diameters. The tubular member further includes
a substantially transverse distal end wall connected to the
medial segment and to the distal end mounting .segment.
Another aspect of the present invention is a laser
enhanced translumsinal angioplasty catheter. The catheter
includes a length of pliable catheter tubing insertable by its
distal end into an artery, and a Eirst lumen in the catheter
tubing extends from its proximal end to the distal end. An
optical fiber is provided in the first lumen for transmitting
laser energy from the proximal end of the catheter ~ubing to the
distal end. A catheter balloon is mounted to the catheter tubing
in surrounding relation thereto and positioned proximate the
distal end of the catheter tubing such that a distal tip o~ the
catheter tubing extends distally beyond the balloon. A second
lumen in the catheter tubing extends from the proximal end of the
catheter tubing to a point near the distal end and open to the
interior of the balloon. The balloon, in response to a fluid
supplied under pressure through the second lumen, dilates to a
generally cylindrical configuration to engage a segment of the
artery to substantially axially align the balloon and the
arterial segment about a central axis. The balloon includes a
distal wall portion substantially perpendicular to the central
axis and joined to the distal tip.
Preferably the length of the distal tip is substantially
less than the diameter of the balloon. Further, radiopaque
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markers can be provided along the distal sec-tion and on the
distal tip.
The perpendicular or transverse distal wall, in contrast
to the gradually tapered distal walls in conventional catheter
balloons, positively and consistently places the catheter tip in
centered, coaxial relation to the balloon when the balloon is
inflated. At the same time, balloon inflation positions the
balloon in coaxial relation to its contiguous arterial segment.
The result is a distal tip coaxial and centered in relation to
the arterial segment. With the severe profile of the distal
walls and a shortened distal tip, the catheter tip and balloon
may be moved in near proximity to an occlusion requiring
treatment, to further ensure that the laser energy from the
catheter will be directed upon the occlusion. Thus, a
percutaneous transluminal laser angioplasty catheter constructed
in accordance with the present invention is well suited for
accurate centering of the cat~eter tip, and is particularly
useful in substantially straight arterial segments.
IN THE DRA~INGS
For a better appreciation of the above and other features
and advantages, reference is made to the following detailed
description and drawings, in which:
Figure 1 is a perspective view of a laser enhanced
transluminal angioplasty catheter equipped with a catheter
balloon constructed in accordance with the present invention;
Figure 2 is an enlarged side elevation of the balloon
shown in Figure 1 positioned within an artery, with portions of
the artery and balloon wall removed for enhanced illustration of
particular features;
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Figure 3 is a sectional view taken along the line 3-3
in Figure 2 and showing just the balloon;
Figure 4 is a sectional view taken alor,g the line 4-4
in Figure 2, showing just the balloon deflated;
Figure 5 is a sec~ional view taken along -the line 5-5
in Figure 2,
Figure 6 is a sectional view taken along the line 6-6
in Figure 2; and
Figure 7 is a side elevation of the balloon.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
Turning now to the drawings, there is shown in Figure 1
a transluminal angioplasty balloon catheter 16 including a
catheter manifold 18 and a length of pliable catheter tubing 20
attached to the catheter manifold and reinforced by a conical
strain relief member 22. An elongate catheter balloon 24
surrounds a distal region of catheter tubing 20 near the distal
end of the tubing.
Joined to the proximal end of rnanifold 18, through a
manifold Gonnector 26 and a sheath connector 28l is an optical
fiber sheath 30 containing an optical -fiber 32. sheath 30 is
connected at its proximal end to a fiber advance housing which is
not illustrated. For more information concerning such a housing
and its relation to the catheter manifold, reference is made to
U.S. Patent No. 4,669,465, assigned to the assignee of this
application. Briefly, the fiber advance housing and fiber 32 are
moved distally relative to catheter maniFold 18 and sheath 30 to
advance optical f~ber 32 into catheter tubing 20, eventually to a
point near a distal tip 34 of the tubing
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Catheter manifold 18 includes first, second and third
extensions 36, 38 and 40, to which are connected f~rst, second
and third luer fittings 42, 44 and 46. First luer fittiny 42
provides fluids to a balloon inflation lumen 48 (Figure 5~
running through catheter tubing 20 and open to the interior of
balloon 24, thus to control dilation and deflation of the
balloon. Second and third luer fittings 44 and 46 deliver
treatment fluids, as needed, to a central lumen 50 also running
through the catheter tubing and open to the distal end of the
tubing.
With reference to Figures 2 and 7, balloon 24 is
essentially a tubular member constructed of a material such as
polyolefin, or other material suitable for maintaining integrity
of the balloon configuration when under fluid pressure during
normal usage. The balloon has end mounting sections including a
proximal neck 52 and a distal neck 54, each of which is sealed to
catheter tubing 20. ~ proximal section 56 of the balloon is
gradually tapered, diverging forwardly from proximal neck 52 to
an elongate medial section 58 which is cylindrical when balloon
24 is inflated. Joining distal neck 54 and medial section 58 is
an annular, transverse distal wall 60, which is substantially
~perpendicular to a central longitudinal axls 62 of the balloon.
Wall 60 provides a severe profile or blunt distal end in the
balloon, the purpose of which is later explained. The balloon is
symmetrical about axis 62.
A tip mar~er 64 is formed of an endless band of
radiopaque (radio opaque) material such as platinum or gold, and
is mounted around the catheter tubing at distal tip 34. When
catheter tubing 20 is inserted into an artery, tip marker 64
provides a visual indication of the position of the distal tip.
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Somewhat larger radiopaque endless bands, particularly a distal
kalloon marker 66 and a proximal balloon marker 68, are wrapped
around the distal region of the catheter tubing 72 contained
within balloon 24. Balloon markers 66 and 68 are used to
indicate the dilitating length of balloon 24 when in an artery.
Markers 64, 66 and 68 together can confirm a centered, coaxial
relation between distal tip 34 and balloon 24.
Preferably, catheter tubing 20 includes a main -tubing
section 70 and a distal tubing section 72, joined to one another
at a butt seal 74 surrounded hy proximal neck 52. The distal
section includes the distal region plus the part of the tubing at
distal tip 34. Distal section 72 is annular in cross-section
(Figures 3 and 4), and preferably is ~ormed of polyethylene and
by extrusion. ~he tip marker and balloon markers have a similar
configuration.
Figure 3 shows tip marker 64 surrounding distal section
72 of the tubing and in turn surrounded by distal neck 54, as
well as the substantially cylindrical configuration of medial
section 58 when balloon 24 is inflated. By contrast, Figure 4
~0 illustrates that the balloon when deflated can be confined to an
e~fective diameter slightly larger than the neck diameters.
Further it is seen that the distal section 72, over the majority
of its length, includes just central lumen 50.
From Figure 5 it is apparent that main section 70 of the
2~ catheter tubing includes balloon inflation lumen 48 and central
lumen 50. A boundary 76 runs the length of the main section to
separate the central and balloon inflation lumens.
As shown in Figure 6, a cut-out 78 is formed in the
proximal portion of distal section 72 of the catheter tubing,
beginning at butt seal 74. Cut-out 78 forms a continuation of
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balloon inflation lumen 4~, whereby th0 balloon inflation lumen
is open to the interior of balloon 24.
Use o~ ca~he-ter 16, and the advantage afforded by the
structure o~ balloon 24, are best appreciated Prom Figure 2,
showing catheter tubing 20 and balloons 24 containèd within a
generally cylindrical artery 80. A partial occlusion or blockage
82 has formed in a slightly curved portion of artery ao, and the
catheter -tubing is inserted into the artery to remove thP
occlusion 82 according to a procedure now described.
Initially, all air is removed from balloon 24 and
inflation lumen 48, so that the balloon ~ends to assume the
collapsed configuration shown in Figure 4. Another preliminary
step is to introduce a "contrast medium" into artery 80 to map
the artery, thus to accurately locate occlusion 82 and to
determine the required length and diameter of catheter balloon
24.
Following these steps, the catheter tubing is
introduced percutaneously into artery 80, and moved along the
artery until the distal region of the tubing is in a
predetermined treatment position corresponding to the location
shown in F;gure 2. The introduction and positioning is
accomplished by using a guide wire as explained in U.S. Patent
No~ 4,~37,145, April 12, 1988, and assigned to the assignee of
th;s applicat;on. Following positioning, the guide wire is
withdrawn and optical fiber 32 is inserted into and through
central lumen ~0 until its distal end is at least proximate the
distal end of tubing 20. Meanwhile, suction is applied to
balloon inflation lumen 48 in order to maintain the balloon in
its reduced shape.
Following optical fiber insertion, fluid under pressure
is introduced to balloon 24 to inflate it to a selected pressure
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for example two atmospheres. This causes the balloon to dilate
and engage an arterial wall 84, thus to align b~lloon 24
coaxially with the segment of artery 80 contiguous wikh the
balloon. Inflation of the balloon further positions distal tip
34 in coaxial relation to the balloon, and thus substantially
coaxial and centered with respect to artexy 80.
A feature of the present invention resides in the
provision oE distal wall 60, substantially transverse relative to
the elongated balloon and distal tip 34. This orientation
provides a blunt surface which rapidly and reliably positions the
distal tip in its coaxial relation to the balloon each time the
balloon is inflated. Conventional balloons have been provided
with a gradually tapered tip, resembling proximal section 56,
primarily to aid catheter insertion. As compared to such a
gradual tip, the blunt tip more accurately positions the distal
tip in the required coaxial relation. In fact, tests have shown
that the blunt tip balloon consistently exhibits ~ood tip
centering, as compared to the tendency of tapered tips to lie
against arterial walls.
Following balloon inflation, the next step is to advance
optical fiber 32 so that its distal end extends slightly beyond
~distal tip 34. Then, laser energy is applied to the proximal end
of the optical fiber, and transmitted beyond the optical fiber
distal end to treat occlusion ~2.
While ideally suited for use in straight arterial
segments, catheter 16 can be used in slightly curved segments
such as shown in Figure 2, for e~ample with a radius of curvature
no smaller than thirteen inches. The use in curve.d arterial
segments is facilitated not only by the accurate positioning
afforded by transverse distal wall 60, but also due to the lenyth
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of distal tip 34, which is selected to be less than the diameter
of distal wall 60 when balloon 2~ i8 inflated. This permits the
balloon, as well as the end of distal tip 34, to be positioned
near the occlusion, enchancing the utility of balloon marker 64
for determining distal tip positioning. With the balloon
positioned as indicated in ~igure 2, a laser source at the
proximal end of optical fiber 32 is activated and a "hot spot" 86
of laser energy is directed onto the occlusion for treatment.
Thus, the blunt forward wall of the balloon aligns the
distal tip coaxially with the balloon and in spaced relation from
the arterial wall in response to fluid pressure in the balloon.
The tip and balloon markers indicate the position of the distal
tip and balloon, which can be used in connection with arterial
mapping to confirm the proper position of the balloon and distal
tip before firing of the laser.
What is claimed is:
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