Method for forming a guide catheter tip bond

A method for forming a guide catheter with a deformable tip includes setting a mating distal end of a tubular member against a mating proximal end of a soft, deformable tip to form a butt joint. The butt joint is then softened to render the mating proximal and distal ends of the deformable tip and tubular member flowable. The tubular member and the deformable tip are then oscillated along a longitudinal axis such that the materials of the mating proximal and distal ends flow into one another creating a connection zone. The connection zone then solidifies to form a lap joint tip bond that securely fastens the deformable tip to the tubular member.

BACKGROUND OF THE INVENTION 
The present invention relates to the field of angioplasty. In particular, 
the present invention is a method for forming a guide catheter with a 
deformable tip. 
Angioplasty has gained wide acceptance in recent years as an efficient and 
effective method for treating various types of vascular diseases. In 
particular, angioplasty is widely used for opening stenosis in the 
coronary arteries, although it is also used for treatment of stenosis in 
other parts of the vascular system. 
The most widely used form of angioplasty makes use of a guide catheter 
positioned within the vascular system of a patient. The distal end of the 
guide catheter is inserted into the femoral artery located in the groin of 
the patient and is pushed distally up through the vascular system until 
the distal end of the guide catheter is located in the ostium of the 
coronary artery. The proximal end of the guide catheter protrudes outside 
of the patient's body to provide an entryway for subsequent insertion of 
additional angioplasty devices. The additional angioplasty devices 
includes dilatation catheters such as non-over-the-wire and over-the-wire 
balloon catheters. 
Methods for forming catheters having soft, deformable tips are generally 
known. U.S. Pat. No. 4,551,292 to Fletcher et al. discloses one such 
method. Catheter stock is first ground down to form a frusto conical end 
portion. Next, the tapered end of the catheter stock is inserted into a 
suitable mold and a plastic, that is softer than catheter stock, is added 
to the mold to create a softer end portion on the catheter stock. The end 
portion of the catheter is then ground away and a forming tool is used to 
form a bulbous end on the end portion of the catheter. The resulting 
connection exhibits very little surface area contact between the catheter 
stock and the end portion. 
It is evident that there is a continuing need for improved methods for 
forming guide catheters with deformable tips. Specifically, a method for 
forming a guide catheter with a deformable tip is needed that creates a 
lap joint tip bond exhibiting a large amount of surface area contact 
between the mating proximal end of the soft, deformable tip and the mating 
distal end of the main tubular member that makes up the guide catheter. 
SUMMARY OF THE INVENTION 
The present invention is a method of coupling a deformable first shaft 
member to a second shaft member by forming a high surface area connection 
zone between the first and second members. To form the connection zone, a 
mating proximal end of the deformable first shaft member is set against a 
mating distal end of the second shaft member to form a butt joint. The 
butt joint is then softened to render the mating proximal and distal ends 
of the first and second shaft members flowable. While the mating ends are 
in a flowable state, the first and second shaft members are oscillated 
longitudinally along an axis defined by the longitudinal extent of the 
first and second shaft members. The oscillating motion causes the mating 
proximal end and mating distal end to flow into one another, thereby 
forming a connection zone. The connection zone is then allowed to 
solidify. This method results in a solidified connection zone with a large 
amount of surface area contact between the first and second shaft members. 
This large amount of surface area contact creates a bond that firmly 
couples the deformable first shaft member to the second shaft member. 
In application, the first shaft member is a soft, tubular, deformable tip 
and the second shaft member is a thermoplastic, tubular member. The method 
of the present invention is used to secure the deformable tip to the 
tubular member to form a guide catheter with a deformable tip on its 
distal end. 
In practice, a rigid mandrel is inserted through the deformable tip such 
that a portion of the mandrel extends past the mating proximal end of the 
deformable tip. Next, a sleeve member is slid over the tip so that a first 
section of the sleeve member extends about the mating proximal end. The 
mating distal end of the tubular member is then set against the proximal 
end of the deformable tip to thereby form the butt joint. In this 
position, a second section of the sleeve member extends about the mating 
distal end of the tubular member, and the portion of the mandrel that 
extends past the mating proximal end of the tip is received within the 
mating distal end of the tubular member. 
The tubular member is secured by a clamp member against movement relative 
to the deformable tip and heat from a heat source is applied to the 
deformable tip and tubular member to soften the mating proximal and distal 
ends at the butt joint. While heat is applied to the butt joint, the 
deformable tip is continuously forced against the tubular member by way of 
a pressure member to maintain contact between the mating proximal and 
distal ends. Softening of the butt joint renders the mating proximal end 
of the deformable tip and the mating distal end of the tubular member 
flowable. 
In one embodiment, the butt joint is heated for 45 seconds at a temperature 
430.degree. F. while the pressure member maintains 10 p.s.i. of pressure 
against the deformable tip. The mandrel and the sleeve member prevent the 
mating proximal and distal ends from bulging radially during softening of 
the butt joint. 
Next, the tubular member and the deformable tip are longitudinally 
oscillated such that the mating distal and proximal ends flow into one 
another. In one embodiment, the tubular member and deformable tip are 
oscillated for a period of three seconds. This procedure causes the 
formation of a lap joint (i.e., connection zone) wherein the mating 
proximal end of the deformable tip forms a tapered apex that extends 
proximally, and wherein the mating distal end of the tubular member forms 
a V-shaped groove that widens distally. 
After the oscillation, the clamp is disengaged from the tubular member, 
thereby releasing the tubular member and the pressure member is disengaged 
from the deformable tip, thereby removing the pressure at the tip. The lap 
joint is then allowed to solidify (i.e., cure) by cooling at room 
temperature. Alternatively, solidification of the lap joint can be 
hastened by immersing the lap joint in an alcohol bath or by the use of a 
circulating air cooler. 
This method of forming a guide catheter with a deformable tip is relatively 
uncomplicated. The method of the present invention produces a lap joint 
tip bond exhibiting a large amount of surface area contact between the 
mating distal end of the tubular member and the mating proximal end of the 
deformable tip that make up the guide catheter. This large amount of 
surface area contact creates an extremely strong bond.

While the above identified drawing figures set forth a preferred 
embodiment, other embodiments of the present invention are also 
contemplated, as noted in the discussion. In all cases, this disclosure 
presents illustrated embodiments of the present invention by way of 
representation and not limitation. It should be understood that numerous 
other modifications and embodiments can be devised by those skilled in the 
art which fall within the scope and spirit of the principles of this 
invention. It should be noted that the figures have not been drawn to 
scale as it has been necessary to enlarge certain portions for clarity. In 
addition, the use of such relational terms as left/right, upper/lower, 
horizontal/vertical, etc. are used herein for reference purposes only and 
are not intended to be limiting features of the invention disclosed. 
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
A distal end of a guide catheter 10 formed in accordance with the method of 
the present invention is illustrated generally in FIGS. 1 and 2. The guide 
catheter 10 includes a first shaft member, such as a soft thermoplastic or 
elastomeric, tubular, deformable tip 12 coupled at its mating proximal end 
14 to a mating distal end 16 of a second shaft member, such as a 
thermoplastic or elastomeric, tubular member 18 (only a portion of which 
is shown in FIG. 1). The deformable tip 12 is coupled to the tubular 
member 18 by way of a connection zone, such as a lap joint tip bond 20. 
The method of forming a guide catheter with a deformable tip in accordance 
with the present invention produces the lap joint tip bond 20, wherein the 
mating proximal end 14 of the deformable tip 12 forms a tapered apex 22 
that extends proximally, and the mating distal end 16 of the tubular 
member 18 forms a V-shaped groove 24 that widens distally (see FIG. 2). A 
partial butt joint 26 forms between a flat edge portion 28 of the mating 
proximal end 14 and a flat edge section 30 of the mating distal end 16 due 
to a coating of lubricous material 31, such as TEFLON, on an inner wall of 
the tubular member 18. The lap joint tip bond 20 occurs as a blending of 
the materials from which the deformable tip 12 and tubular member 18 are 
formed. 
The lap joint tip bond 20 as illustrated in FIG. 1 has been formed in 
accordance with the method of the present invention. FIG. 2 is provided 
only for clarity and illustrates the lap joint tip bond 20 in an exploded 
condition. It is to be understood that the shape of the mating proximal 14 
of the deformable tip 12 and the shape of the mating distal end 16 of the 
tubular member 18 shown in FIGS. 1 and 2 is produced only after the method 
of the present invention has been carried out. 
The method for forming the lap joint tip bond 20 is illustrated in FIGS. 
3-6, 8 and 9. As shown in FIG. 3, a rigid mandrel 32 is first inserted 
through the deformable tip 12 such that a first portion 34 of the mandrel 
32 extends past the mating proximal end 14 of the deformable tip 12. Next, 
as seen in FIG. 4, a sleeve member 36 is slid over the deformable tip 12 
so that a first section 38 of the sleeve member 36 extends about the 
mating proximal end 14. As seen in FIG. 5, the mating distal end 16 of the 
tubular member 18 is then set (i.e., abutted) against the mating proximal 
end 14 of the deformable tip 12 to thereby form a butt joint 40. In this 
position, a second section 42 of the sleeve member 36 extends about the 
mating distal end 16 of the tubular member 18, and the portion 34 of the 
mandrel 32 that extends past the mating proximal end 14 of the deformable 
tip 12 is received within the mating distal end 16 of the tubular member 
18. 
As is apparent from FIGS. 3 and 4, at the start of the method of the 
present invention, the mating proximal end 14 of the deformable tip 12 has 
a first flat end edge 44 and the mating distal end 16 of the tubular 
member 18 has a second flat end edge 46. The sleeve member 36 and the 
mandrel 32 are sized to snugly receive or be snugly received, 
respectively, by the deformable tip 12 and tubular member 18. 
Next, as seen in FIG. 6, the combination of the tubular member 18, 
deformable tip 12, mandrel 32 and sleeve member 36 is inserted between the 
clamp members 48 of a clamping device 50 such that the tubular member 18 
is positioned between the clamp members 48. A distal end 52 of the 
deformable tip 12 is received by a pressure member 54. As best seen in 
FIG. 7, the pressure member 54 includes a through opening 56 extending 
from a proximal end 58 to a distal end 60 of the pressure member 54. The 
proximal end 58 includes a pressure ledge 62 defined by a circular bottom 
wall 64 and a circumferential side wall 66. As seen in FIG. 6, the 
pressure ledge 62 is configured to receive the distal end 52 of the 
deformable tip 12, while the through opening 56 is configured to slidably 
receive a second portion 68 of the mandrel 32. 
Next, as seen in FIG. 8, the clamp members 48 of the clamping device 50 are 
engaged with the tubular member 18 to secure the tubular member 18 against 
movement relative to the deformable tip 12. Heat (as represented by the 
wavy arrows 70) from a heat source 72 is applied to the deformable tip 12 
and tubular member 18 to soften the mating proximal and distal ends 14 and 
16 at the butt joint 40. Approximately two thirds of the heat from the 
heat source 72 is directed to the mating distal end 16 of the tubular 
member 18, while the remaining one third of the heat is directed to the 
mating proximal end 14 of the deformable tip 12. This is done because the 
material used to form the tubular member 18 is stiffer then the material 
used to form the deformable tip 12. Therefore, more heat is required to 
soften the mating distal end 16 of the tubular member 18 then is required 
to soften the mating proximal end 14 of the deformable tip 12. 
While heat is applied to the butt joint 40, the deformable tip 12 is 
continuously forced against the tubular member 18 by way pressure exerted 
by the pressure member 54 (see FIG. 8). The pressure is exerted along a 
longitudinal axis 74 formed by the deformable tip 12 and tubular member 
18. The pressure of the pressure member 54 maintains contact between the 
mating proximal end 14 of the deformable tip 12 and the mating distal end 
16 of the tubular member 18. The heat from the heat source 72 and the 
pressure from the pressure member 54 act to soften the butt joint 40 and 
render the mating proximal end 14 of the deformable tip 12 and the mating 
distal end 16 of the tubular member 18 flowable. 
Heat is applied to the butt joint 40 for a sufficient period of time to 
soften the butt joint 40. In one embodiment, the tubular member 18 and 
deformable tip 12 are both formed of polyether block amide and a 
radiopaque compound, except that the material of the deformable tip 12 has 
a lower durometer then the material of the tubular member 18. In other 
words, the tubular member 18 is stiffer than the deformable tip 12. In 
addition to the different durometers, the tubular member 18 also includes 
the coating of lubricous material 31 while the deformable tip 12 has no 
such coating. In one embodiment, the tubular member 18 has a durometer of 
66 while the deformable tip 12 has a durometer of 37 and the butt joint 40 
is heated by the heat source 72 for 45 seconds at a temperature 
430.degree. F. while the pressure member 54 maintains 10 p.s.i. of 
pressure against the distal end 52 of the deformable tip 12. The mandrel 
32 and the sleeve member 44 prevent the mating proximal and distal ends 14 
and 16 from bulging radially during softening of the butt joint 40. 
After the butt joint 40 is sufficiently heated and while maintaining the 
heat and pressure, the tubular member 18, the deformable tip 12, the 
mandrel 32, the sleeve member 44, the clamping device 50, and the pressure 
member 54 are all oscillated (as represented by the double headed arrow 
75) relative to the heat source 72 along the longitudinal axis 74 by a 
piston and cylinder device 76 (see FIG. 9). The longitudinal oscillation 
causes the softened mating proximal and distal ends 14 and 16 to flow into 
one another. In one embodiment, the tubular member 18 and the deformable 
tip 12 are oscillated for a period of three seconds. This procedure causes 
the formation of the lap joint tip bond 20 (see FIGS. 1 and 2) wherein the 
mating proximal end 14 of the deformable tip 12 forms the tapered apex 22 
that extends proximally, the mating distal end 16 of the tubular member 18 
forms the V-shaped groove 24 that widens distally, and the partial butt 
joint 26 is formed between the flat edge portion 28 and the flat edge 
section 30 at the coating of lubricous material 31. 
After the oscillation, the clamping device 50 is disengaged from the 
tubular member 18, thereby releasing the tubular member 18, and the 
pressure member 54 is disengaged from the distal end 52 deformable tip 12, 
thereby removing the pressure at the deformable tip 12. The tubular member 
18 with the deformable tip 12 coupled thereto is then removed from the 
heat source 72 and the lap joint tip bond 20 is allowed to solidify (i.e., 
cure) by cooling at room temperature. The heat source 72 remains on so 
that it is ready for the formation of subsequent lap joint tip bonds 20. 
When the lap joint tip bond 20 has solidified, formation of the guide 
catheter 10 is complete. 
Alternatively, solidification of the lap joint tip bond 20 can be hastened 
by immersing the lap joint tip bond 20 in a cooling bath 77 shown in FIG. 
10. The cooling bath 77 includes a bottom wall 78, a pair of spaced, 
upstanding sidewalls 80 and a pair of spaced, upstanding end walls 82. A 
guide catheter support plate 84 is mounted to upper edges of the sidewalls 
80 at a first end of the cooling bath 77. The support plate 84 carries a 
plurality of guide catheter supports 86. A dunking plate 88 is mounted to 
the upper edges of the sidewalls 80 spaced from the support plate 84. 
The cooling bath 76 may be filled with a cooling substance such as an 
alcohol bath 90 which would hasten cooling of the lap joint tip bond 20 
and thereby solidification of the lap joint tip bond 20 via evaporation of 
the alcohol bath 90. As seen in FIG. 10, a guide catheter 20 with a lap 
joint tip bond 20 to be cooled is placed across one of the guide catheter 
supports 86 and beneath the dunking plate 88 which serves to maintain the 
lap joint tip bond 20 immersed in the alcohol bath 90. The lap joint tip 
bond 20 is left in the alcohol bath 90 for a sufficient period of time to 
cool the lap joint tip bond 20. 
Solidification of the lap joint tip bond 20 can be alternatively hastened 
by the use of a circulating air cooler 92, such as a VORTEC cooler as 
shown in FIG. 11. The circulating air cooler 92 includes a bottom wall 93, 
a rear wall 94, a front wall 95, a pair of sidewalls 96 and a top wall 98. 
An air exhaust port 100 extends out through the front wall 95. An air 
inlet tube 102 extends through the exhaust port 100 and into the confines 
of the circulating air cooler 92. A guide catheter 10 with a lap joint tip 
bond 20 to be cooled is inserted into the cooler 92 through one of a 
plurality of slots 103 in the rear wall 94 such that the lap joint tip 
bond 20 is within the confines of the circulating air cooler 92. Air (as 
represented by the arrow 104) is forced into the confines of the 
circulating air cooler 92 through the air inlet tube 102. The air 
circulates within the cooler 92 and is exhausted through the exhaust port 
100 (as represented by the arrow 105). The circulating air within the 
circulating air cooler 92 hastens cooling of the lap joint tip bond 20 and 
thereby solidification of the lap joint tip bond 20. The lap joint tip 
bond 20 is left in the circulating air cooler 92 for a sufficient period 
of time to cool the lap joint tip bond 20. 
This method of forming a guide catheter 10 with a deformable tip 12 is 
relatively uncomplicated. The method of the present invention produces a 
high strength lap joint tip bond 20 exhibiting a large amount of surface 
area contact between the mating distal end 16 of the tubular member 18 and 
the mating proximal end 14 of the deformable tip 12 that make up the guide 
catheter 10. This large amount of surface area contact creates an 
extremely strong bond. 
Although the present invention has been described with reference to 
preferred embodiments, workers skilled in the art will recognize that 
changes may be made in form and detail without departing from the spirit 
and scope of the invention.