Note: Descriptions are shown in the official language in which they were submitted.
2a~278
WO9l/13~9 PCT/US91/01571
DILATATION CAT~ETER
BACKGROUND OF THE INVENTION
Field of the Invention - This invention relates to
medical catheters, particularly those for opening lesions
5 in arteries.
Catheters designed for steering through a tortuous
path of small arteries, such as the coronary arterles,
have been of two general types. One type slides over a
separate guidewire. The second type involves a guidewire
10 built into the catheter. The guidewire and catheter are
inserted in the artery as a unit.
Such catheters built on a wire are steered through
the arteries by directing a bent tip in the proper
direction to enter a branch. The guidewire is rotated to
15 turn the bent tip in the proper direction. A known
problem in the prior art on-the-wire catheters is that
rotation of the guidewire may cause the balloon in the
catheter to twist and wrap up around the guidewire. This
will cause later problems in inflation and deflation of
2~ the balloon.
This problem is taught in United States Patent No.
4,664,113 which explai-ns the problems with balloon wrap.
That patent discloses a typical prior art device where
the distal end of the balloon is fixed directly to the
25 guidewire. When the guidewire rotates, the balloon
twists. In an attempt to mitigate this problem, that
patent limited rotation of the wire. Such li- 'ations on
rotation are well known in other cathet~r arts, but is
found to be necessary for a particular functional purpose
30 in wires of the type disclosed with a balloon honded
directly to a guidewire. What is needed in the art is a
balloon structure which performs the functions of
traditional on-the-wire catheters, but is not subject to
the balloon wrap problem of the style in United States
35 Patent No. 4,664,113.
One other attempt to solve this problem is a design
such as the P~OBE catheter from USCI. This has a
WO91/13~9 '~ PCT/US91/01571
guidewire independent of the end of the balloon.
However, the device does not have sufficient structural
integrity for retaining the guidewire relative to the
catheter structure. A structure is needed which prevents
5 wrap but which is structurally sound and preserves the
integrity of the tip area.
SUMMARY OF THE INVENTION
A catheter constructed according to the present
invention involves a torque transmitting shaft, a
l0 flexible catheter body having a lumen for passage of the
shaft, a balloon mounted on the distal end of the
catheter body; a flexible tubing extending from within
the balloon out to a distal tip of the catheter; the
flexible tubing being bonded to the distal end of the
15 balloon so that the shaft is free to move relative to the
distal end of the balloon.
In the preferred embodiment the flexible tubing
includes a spring covered by a tip tube. The spring
attached at its proximal end and distal ends to the
20 shaft.
BRIEF DESCRIPTION OF THE DRAWINGS
Fig. l is a side plan view of a catheter constructed
according to the present invention partially broken way.
Fig. 2 is a cross sectional view of a distal portion
25 of the catheter of Fig. l.
Fig. 3 is a cut-away, partially cross sectional,
view of a proximal section of the catheter of Fig. l,
including the manifold.
DETAILED DESCRIPTION OF THE DRAWINGS
The catheter l0 constructed according to the present
invention includes a flexible catheter body 12, a torque
transmitting shaft 14, a balloon 16, a flexible tip 18
and a manifold or handle 20. Handle 20 includes an arm
WO91/13649 29~a278 PCT/US91/01571
24 for mounting balloon inflation equipment and a second
arm 26 for guidewire mounting. A rotatable handle 28 is
mounted for rotation within arm 26.
As shown in Fig~ 2, catheter body 12 includes a body
5 spring 40 which is a spring wound of metal of a
rectangular cross section. Body springs of prior art
devices such as the Versaflex Omniflex catheter are
suitable. ~ody spring 40 forms a lumen 42 through which
passes shaft 14. Mounted within lumen 42 is a smaller
10 diameter stainless steel spring 44 which is brazed to
body spring 40 at braze 46.
In the illustrated embodiment, body spring 40 has an
outside diameter of .30 inches. Spring 44 has an outside
diameter of .026 inches.
Flexible plastic tubing 48 is mounted over body
spring 40, as in the prior art Omniflex device. In the
preferred embodiment, tube 48 is made of polyethylene
shaft stock.
Tubing 48 is tapered at its distal section 50 where
20 it narrows to fit over spring 44. Balloon 16 has a
proximal section 52 mounted over the tapered section 50
of tube 48O Spring 48 is attached to tube 48 by
adhesive. In the preferred embodiment, section 52 o~
balloon 16 is cut off with a square non-tapered end. The
25 section 50 of tube 48 which is not covered by balloon
portion 52 is filled in with adhesive 54 to make a smooth
external surface of the outside diameter of tube 48.
Balloon proximal portion 52 and adhesive 5 are generally
equal in diameter. In the preferred embodiment, adhesive
30 54 is in ultraviolet cured adhesive.
A radiopague marker band 60 is mounted within
balloon 16 on shaft 14, preferably by brazing. Marker 60
is made and attached using common prior art techniques.
MarXer 60 is preferably a platinum cylinder, but may be
35 platinum wire wound around shaft 12. In order to have a
smooth transition from shaft 14 to marker 60, a ramp of
WO91/13~9 PCT/US91/01571
~i327~
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adhesive 62 formed at either end of the marker 60. In
the preferred embodiment, adhesive 62 is cyanoacrylate.
Shaft 14 has a tapered section 64 and a flattened
tip 66. Mounted on flattened tip 66 by brazing is a flat
5 ribbon wire 68. A metallic tip 70 is brazed to the tip
of flat wire 68.
A tip spring 72 is mounted over shaft 14. Tip
spring 72 has a tightly coiled medial section 74, a
spread flexible proximal section 76 and a spread flexible
10 distal section 78. The proximal end of section 76 is
brazed to shaft 14 at 80. Distal section 78 is brazed to
tip 70. Therefore, spring 72 is fixed at either end but
flexes throughout the rest of its structure. A tip tube
82 is mounted over spring 72. Tube 82 is attached to
15 shaft 14 by adhesive 84, which in the preferred
embodiment is cyanoacrylate. This seals the interior of
tube 82 from interior balloon 16. Tip tube 82 extends
distally through the distal end 84 of balloon 16. Distal
end 84 of balloon 16 is bonded to tube 82 by adhesive,
20 which in the preferred embodiment is an ultraviolet cured
adhesive. In turn, tube 82 is bonded to coil 82 by
adhesive.
The structure of catheter 10 provides a free moving
guidewire within spring 72 so that the catheter is not
25 susceptible to balloon wrap. When shaft 14 is rotated,
it moves freely within lumen 42 of body spring 40 and
within tip spring 72. If shaft 42 is overturned by the
user of the catheter, the torque is taken up in spring 72
and not transmitted to balloon 16. Both proximal section
30 76 and distal section 78 of tip spring 72 are loosely
wound springs which will absorb the torquing effect.
This allows multiple turns of shaft 14 without affect on
balloon 16.
As a reminder to the physician to return shaft 14 to
35 the center position, means are provided to indicate the
number of turns made. In manifold 20,
WO91/13649 ~ 7 8 PCT/US91/01571
shaft 14 is attached to strain relief means 90. Shaft 14
continues through lumen 92 through silicone seal 9~. A
threaded lumen 95 has female threads 96. Guidewire
housing 97 has male threads which mate with threads 98.
5 The interacting threads s~ueeze silicone seal 94 to
prevent backflow of fluid out of lumen 92.
Guidewire housing 97 has a longitudinal groove lO0
which has a semicircular cross section. Rotatable handle
28 is mounted over second housing 97. Rotatable handle
lO 28 is held to guidewire housing 97 by spring clip 104.
Rotatable handle 28 has a bore 105 which is cut with
helical threads 106. The cross section of helical thread
106 is a semicircle matching in diameter the cross
section of longitudinal groove lO0. A ball llO is
15 mounted to ride within groove lO0 and helical threads
108. As rotatable handle 28 is turned relative to
guidewire ~housing 97, ball llO follows helical grooves
106 and moves, correspondingly, up and down longitudinal
groove lO0. When ball llO reaches an end of groove lO0,
20 handle 28 can no longer rotate in that direction.
Therefore, the amount of turn of rotatable handle 28
relative to housing 97 depends on the number of turns of
helical groove 106.
In the embodiment illustrated, there can be four
25 turns in either direction of handle 28. Although balloon
twist does not occur in the design illustrated, the
limitation on rotation reminds the physician that
rotation has occurred in one direction and that further
rotation in that direction could occur spring compression
30 in the tip section.
