U.S. patent application number 17/004980 was filed with the patent office on 2020-12-17 for guiding catheter having shape-retentive distal end.
This patent application is currently assigned to Surefire Medical, Inc.. The applicant listed for this patent is Surefire Medical, Inc.. Invention is credited to Grayson Beck, David Benjamin Jaroch.
Application Number | 20200391003 17/004980 |
Document ID | / |
Family ID | 1000005051854 |
Filed Date | 2020-12-17 |
View All Diagrams
United States Patent
Application |
20200391003 |
Kind Code |
A1 |
Jaroch; David Benjamin ; et
al. |
December 17, 2020 |
GUIDING CATHETER HAVING SHAPE-RETENTIVE DISTAL END
Abstract
A guiding catheter has a proximal portion constructed of a
tubular braid and a shape-retentive distal portion including a
superelastic hypotube cut to define particular mating, support,
shape-retentive and flexibility characteristics. A tubular liner
extends through both of the tubular braid and the hypotube. The
hypotube is joined to the braid using a mechanical interlock that
has high torque transfer from the braid to the hypotube. A short
portion of high stiffness polymer tube is provided at a joint
between the braid and the hypotube. A polymeric outer jacket is
provided over the proximal and distal portions, including the
polymer tube. The jacket is heat set over the hypotube to remove
residual stress.
Inventors: |
Jaroch; David Benjamin;
(Arvada, CO) ; Beck; Grayson; (Davis, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Surefire Medical, Inc. |
Westminster |
CO |
US |
|
|
Assignee: |
Surefire Medical, Inc.
Westminster
CO
|
Family ID: |
1000005051854 |
Appl. No.: |
17/004980 |
Filed: |
August 27, 2020 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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15864978 |
Jan 8, 2018 |
10806893 |
|
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17004980 |
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62444554 |
Jan 10, 2017 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
A61M 25/0051 20130101;
A61M 2205/0266 20130101; A61M 25/008 20130101; A61M 25/0662
20130101; A61M 25/0013 20130101; A61M 25/0041 20130101; A61M
25/0068 20130101 |
International
Class: |
A61M 25/00 20060101
A61M025/00; A61M 25/06 20060101 A61M025/06 |
Claims
1. A catheter, comprising: a tubular member having a proximal end
and a distal end, a portion of the tubular member covered by a
resin, the portion of the tubular member having a first outer
surface and a diametrically opposite second outer surface, the
tubular member manufactured by a process in which the portion is
heat treated to elevate the resin at the first outer surface to a
temperature at or above a melting point of the resin so that the
resin is fluidized during manufacture, while the resin at the
second outer surface is raised to a temperature below the melting
point of the resin.
2. The catheter of claim 1, wherein: the resin at the first inner
surface is relieved of a compressive stress.
3. The catheter of claim 1, wherein the resin at the second outer
surface is relieved of tensile stress.
4. The catheter of claim 1, wherein: the resin is elastic in a
range of room temperature to body temperature.
5. The catheter of claim 1, wherein: the resin is provided with a
radiopacifying agent.
6. The catheter of claim 1, wherein: the distal end of the catheter
includes an elastic tubular element, and the resin is provided over
the tubular element.
7. The catheter of claim 6, wherein: the tubular member comprises a
flexible hypotube.
8. The catheter of claim 6, wherein: the tubular element is a
superelastic metal alloy hypotube.
9. The catheter of claim 8, wherein: the hypotube is cut in a
pattern, wherein different longitudinal portions of the pattern
have different functional characteristics.
10. The catheter of claim 9, wherein: the hypotube is laser etched
into the pattern.
11. A catheter, comprising: a tubular member having a proximal end
and a distal end, a portion of the tubular member covered in a
resin and set in a curve such that its longitudinal axis extends
along the curve, the portion defining an inner, exterior surface
that is concave, and an outer, exterior surface that is convex
along the curve, the resin in a state of released residual
stress.
12. The catheter of claim 11, manufactured by a process wherein the
portion of the tubular member is heat treated such that the resin
at the inner, exterior surface is raised to a temperature at or
above a melting point of the resin so that the resin is fluidized
during manufacture, while the resin at the outer, exterior surface
is raised to a temperature below the melting point of the
resin.
13. The catheter of claim 11, wherein: the resin of the portion of
the tubular member at the inner, exterior surface is distributed
evenly on the inner, exterior surface without folds in the curve
along the longitudinal axis.
14. The catheter of claim 11, wherein: the resin at the outer,
exterior surface is relieved of a tensile stress in the resin.
15. The catheter of claim 11, wherein: the resin at the inner,
exterior surface is relieved of a compressive stress in the
resin.
16. The catheter of claim 11, wherein: the resin of the portion of
the tubular member is elastic in a range of room temperature to
body temperature.
17. The catheter of claim 11, wherein: the resin of the portion of
the tubular member is provided with a radiopacifying agent.
18. The catheter of claim 11, wherein: the distal end of the
catheter includes an elastic tubular element, and the resin is
provided over the tubular element.
19. The catheter of claim 18, wherein: the tubular element is a
superelastic metal alloy hypotube.
20. The catheter of claim 19, wherein: the hypotube is cut in a
pattern, wherein different longitudinal portions of the pattern
have different functional characteristics.
21. The catheter of claim 20, wherein: the hypotube has a sidewall,
and the pattern is laser etched through the sidewall of the
hypotube.
22. The catheter of claim 11, wherein: tubular member is located at
a distal end of the catheter.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a divisional of U.S. Ser. No.
15/864,978, filed Jan. 8, 2018, which claims benefit to U.S.
Provisional Ser. No. 62/444,554, filed Jan. 10, 2017, which are
hereby incorporated by reference herein in their entireties.
BACKGROUND
1. Field
[0002] The present invention relates to catheters. More
particularly, the present invention relates to guiding catheters
that facilitate the introduction and support of secondary devices
passed through their inner lumen.
2. State of the Art
[0003] Typical interventional radiology procedures involve the
introduction of catheters into the circulatory system, typically
using femoral or radial access points. One of the primary tools
used in such procedures are angiographic catheters that are
intended to act as a fluid conduit for contrast mapping of the
patient's anatomy prior to treatment. Such catheters are often
designed with uniquely shaped distal segments intended to
facilitate tracking and placement of the device within specific
points of the patient's anatomy.
[0004] Angiographic catheters are typically designed to accommodate
a guidewire of 0.035 inch or 0.038 inch diameter, which are used to
advance the catheter though the anatomy prior to final placement.
This small inner lumen size requirement allows angiographic
catheters to be designed with thick walls that serve to provide
mechanical support to the device and allow for the shaped distal
segments to have a high degree of original shape retention upon
straightening and initial introduction to the anatomy.
[0005] Angiographic catheters, being intended as a fluid conduit
for a contrast agent, are typically not lined with materials that
reduce friction when interfaced with a solid material, as is the
case during introduction of a guidewire or microcatheter through an
angiographic catheter. In these instances friction is reduced but
not eliminated by a hydrophilic coating applied to the outer
surface of the guidewire or microcatheter.
[0006] In contrast, guiding catheters are specifically designed to
facilitate the introduction and support of secondary devices passed
through their inner lumen. Such secondary devices may include, by
way of example, guidewires, microcatheters, lasers, and stents.
Like angiographic catheters, guiding catheters often have a shaped
distal segment intended to ease placement within desired anatomy
and provide additional support to secondary device
introduction.
[0007] In order to further facilitate introduction of secondary
devices with a range of sizes and surface geometries into the lumen
of a guide catheter, guiding catheters are designed to maximize
inner lumen space and minimize friction using a variety of low
surface energy lining material such as polytetrafluoroethylene
(PTFE). The relatively large inner lumen size corresponds to a
subsequent reduction in wall thickness. The catheter walls are then
typically reinforced with wire coils or braid to retain acceptable
mechanical properties during use. However, the reduced overall wall
thickness and the lack of volume of high shape retentive material
limits distal shape geometry and support.
[0008] Shape retention refers to how well a device maintains its
original shape during clinical usage. As the shape is intended to
conform with specific anatomies, maintenance of the shape though
the procedure is critical for initial ease of placement and usage
of the device. However, tests have shown that on-market guiding
catheters have a significant loss in shape retention. By way of
example, testing has shown that an on-market angiographic catheter
2 having a distal tip 4 pre-shaped into a 180.degree. reverse turn
(Prior Art FIG. 1A), after being straightened in a manner that
simulates introduction into the patient, will only return to a
145.degree. reverse turn (Prior Art FIG. 1B). Moreover, on-market
guiding catheters exhibit even worse performance. By way of
example, catheter 6 having a distal tip 8 similarly pre-shaped into
a 180.degree. reverse turn (as distal tip 4), will only return to a
110.degree. reverse turn after straightening (Prior Art FIG. 1C).
This could lead to difficulties in guiding the secondary devices to
the vessels of interest.
[0009] Support, namely backup support, refers to the amount of
support or resistance to deflection from a set shape the guiding
catheter provides when an accessory device is passed through the
lumen of the guiding catheter. In severe catheter shapes, such as
the 180.degree. bend referenced above, the guiding catheter
redirects an upward pushing force downward into the vasculature.
Backup support is a measure of how much force can be redirected and
how well the direction of force is maintained.
SUMMARY
[0010] A guiding catheter is provided having a length with a
proximal portion and a distal portion. The proximal portion is
constructed with a tubular braid. The distal portion comprises a
hypotube cut to define particular mating, support, shape-retentive
and flexibility characteristics. A polymer tubular liner extends
through both of the tubular braid and the hypotube. A polymer outer
jacket extends over both of the proximal and distal portions.
[0011] The shape-retentive hypotube is preferably comprised of an
elastic material, and more preferably a superelastic material, such
as a nickel titanium alloy or other elastic or superelastic metal
alloy. The hypotube is cut into a functional design that defines at
least three longitudinal segments of respective properties. A
distal segment is a highly flexible portion adapted to deflect in
any direction across a frontal plane. A central segment is a
curvature portion adapted to define a particular curve along its
central axis and return to such curvature when deflected along the
axis at the front plane. A proximal segment is a mating portion
adapted to couple the hypotube relative to the proximal portion of
the guiding catheter. A leading arm segment is optionally provided
between the curvature segment and the distal segment and is
designed to deflect with an intermediate resistance along a single
axis of the frontal plane. A support segment is optionally provided
between the mating segment and the curvature segment, and is
adapted to provide flexural support (resist deflection) when the
relatively more distal segments are under load. The various
segments are preferably defined with respective patterns cut into
the hypotube.
[0012] The hypotube is coupled to the braid at a joint using a
mechanical interlock that has high torque transfer from the braid
to the hypotube. In addition, a short portion of relative higher
stiffness polymer tubing (higher than the outer polymer jacket both
proximal and distal of the joint) is provided at the joint between
the braid and the hypotube. Such higher stiffness polymer tubing
redirects force from the joint to the proximal and distal portion
of the outer jacket to prevent buckling and kinking of the catheter
at the joint.
[0013] The outer jacket is heat set over the hypotube. The resin of
the jacket is heat set such that at least the axis of the curvature
portion of the hypotube extends along a curve, with the inner,
exterior, concave surface of the hypotube under compression and the
outer, exterior, convex surface (along the apex side) of the
hypotube curved under tension. The resin is differentially heat set
such that the resin along the inner concave surface is raised to a
temperature at or above the melting point of the resin, while the
resin at the outer convex surface is raised to a temperature below
the melting point of the resin. The resin at the inner concave
surface is able to fluidize, relieving residual compressive stress
and distributing the resin evenly over the inner, concave surface.
The resin at the outer, exterior, convex surface does not melt,
preventing exposure of the underlying hypotube, as a resin under
tension tends to thin over the upper surface. However, the resin at
this outer, exterior surface is permitted to reach a plastic
transformation temperature that relieves tensile stress in the
material. A system for carrying out the heat setting of the resin
onto the hypotube is provided.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] Prior Art FIG. 1A shows a prior art angiographic catheter in
a pre-shaped configuration for use.
[0015] Prior Art FIG. 1B shows the prior art angiographic catheter
deformed from the pre-shaped configuration after being temporarily
straightened.
[0016] Prior Art FIG. 1C shows a prior art guiding catheter
deformed from its pre-shaped configuration after being temporarily
straightened.
[0017] FIG. 2 is a broken partial perspective view of a catheter
described herein.
[0018] FIG. 3 is a first pattern for cutting a hypotube for use in
a distal shape-retentive portion of the catheter.
[0019] FIG. 4 is an enlarged section of a central curvature portion
of the first pattern.
[0020] FIG. 5 shows the central curvature portion of the hypotube
cut according to the first pattern and subject to torsion.
[0021] FIG. 6 is a second pattern for cutting a hypotube for use in
a distal shape-retentive portion of the catheter.
[0022] FIG. 7 is third pattern for cutting a hypotube for use in a
distal shape-retentive portion of the catheter.
[0023] FIG. 8 is an enlarged section of a central curvature portion
of the third pattern.
[0024] FIG. 9 shows the central curvature portion of the hypotube
cut according to the third pattern and subject to torsion.
[0025] FIG. 10 is a fourth pattern for cutting a hypotube for use
in a distal shape-retentive portion of the catheter.
[0026] FIG. 11 is an enlarged section of a central curvature
portion of the fourth pattern.
[0027] FIG. 12 shows the central curvature portion of the hypotube
cut according to the fourth pattern and subject to torsion.
[0028] FIG. 13 is a fifth pattern for cutting a hypotube for use in
a distal shape-retentive portion of the catheter.
[0029] FIG. 14 is an enlarged section of a central curvature
portion of the fifth pattern.
[0030] FIG. 15 shows the central curvature portion of the hypotube
cut according to the fifth pattern and subject to torsion.
[0031] FIG. 16 is an enlarged section of a pattern for cutting the
distal segment of the hypotube.
[0032] FIG. 17 shows the flexibility of the distal segment of the
hypotube cut according to the first through fifth patterns.
[0033] FIG. 18 illustrates the flexibility of the distal segment of
the hypotube cut according to the patterns.
[0034] FIGS. 19 and 20 illustrate the function of spine elements in
the hypotube when subject to torsion and recovery from torsion.
[0035] FIG. 21 is an enlarged section of a pattern for cutting the
proximal segment of the hypotube.
[0036] FIG. 22 shows the flexibility of the proximal segment of the
hypotube cut according to the first through fifth patterns.
[0037] FIG. 23 shows the butt joint between the braid and the
distal shape retentive section of the catheter.
[0038] FIG. 24 is a longitudinal section view of the distal end of
the catheter, including the butt joint of FIG. 23.
[0039] FIG. 25 shows the interlock between a tab at the proximal
end of the hypotube and the braid.
[0040] FIG. 26 illustrates the kink resistance of the catheter at
the butt joint.
[0041] FIGS. 27 and 28 show a system for heat setting a polymer
jacket over the shape-retentive distal end of the catheter.
[0042] FIG. 29 shows the catheter prior to heat-setting.
[0043] FIGS. 30 through 34 show a method of heat-setting the
shape-retentive distal end of the catheter.
[0044] FIG. 35 shows the catheter after heat-setting.
[0045] FIG. 36 is an enlarged view showing features of the catheter
prior to heat-setting.
[0046] FIG. 37 is an enlarged view showing features of the catheter
after heat-setting.
[0047] FIG. 38 is an enlarged view showing features of a curvature
segment of the hypotube.
[0048] FIG. 39A illustrates the force to deflect a hypotube with an
unbiased pattern of struts.
[0049] FIG. 39B illustrates the force to deflect a hypotube with an
unbiased pattern of struts that has preferential bending along a
heat-set axis.
[0050] FIG. 40A illustrates the force to deflect a hypotube with
parallel spines that alter force deflection.
[0051] FIG. 40B illustrates the force to deflect a hypotube with
parallel spines that alter force deflection and which also has
preferential bending along a heat-set axis.
[0052] FIG. 41A illustrates the force to deflect a hypotube with a
biased pattern of struts.
[0053] FIG. 41B illustrates the force to deflect a hypotube with a
biased pattern of struts that has preferential bending along a
heat-set axis.
[0054] FIG. 42 is a portion of an unbiased hypotube for a guiding
catheter.
[0055] FIG. 43 illustrates a pattern for cutting the portion of the
hypotube shown in FIG. 42.
[0056] FIG. 44 is a portion of a biased hypotube for a guiding
catheter.
[0057] FIG. 45 illustrates a pattern for cutting the portion of the
hypotube shown in FIG. 44.
[0058] FIG. 46 illustrates an embodiment of the guiding catheter in
a natural unbiased configuration.
[0059] FIG. 47 illustrates the guiding catheter of FIG. 46
straightened for insertion into a vessel.
[0060] FIGS. 48 through 50 illustrate one method of inserting the
guiding catheter of FIGS. 46 and 47.
[0061] FIGS. 51 and 52 illustrate another method of inserting the
guiding catheter of FIGS. 46 and 47.
DETAILED DESCRIPTION
[0062] With reference to the following description, the terms
"proximal" and "distal" are defined in reference to the hand of a
user of the devices and systems described herein, with the term
"proximal" being closer to the user's hand, and the term "distal"
being further from the user's hand such as to be often located
further within a body of the patient during use.
[0063] Referring now to FIG. 2, a guiding catheter 10 is shown. The
guiding catheter 10 has a proximal portion 12 having a proximal end
14 and a distal portion 16 having a distal end 18, and a lumen 20
and a length extending from the proximal end 14 to the distal end
18. The guide catheter 10 may be provided in different sizes, e.g.,
3French to 7French for use within different vessels. By way of
example, for a 5French size device, the following dimensions are
suitable. The length is generally 65 to 110 cm. The catheter 10 has
an outer diameter of 0.066 inch to 0.072 inch, a lumen 20 diameter
of 0.054 inch to 0.058 inch, and a wall thickness of 0.004 inch to
0.009 inch between the inner and outer diameters. When the guide
catheter is larger or smaller than 5French, the wall thicknesses
and diameters are scaled up or down accordingly, while the length
may remain consistent or different as necessary for the procedure.
The proximal portion 12 includes a hub 22, optionally with leur
lock, to facilitate entry of a secondary instrument into the lumen
20 of the guiding catheter.
[0064] The major length of the catheter 10 preferably comprises a
tubular braid 46. At the distal end of the tubular braid 46, a
distal shape-retentive section 24 is provided. The shape-retentive
section 24 comprises a hypotube 26 cut to define particular mating,
support, shape-retentive and flexibility characteristics, as
described in more detail below. The shape-retentive hypotube 26 is
preferably comprised of an elastic material, and more preferably a
superelastic material, such as a nickel titanium alloy, stainless
steel alloy, or other suitable metal alloy or non-metal material. A
polymer tubular liner 31 extends through the braid and hypotube 26,
and defines a longitudinal axis A and working lumen of the guiding
catheter. The braid 46 and hypotube 26 are also coated in a
thermoplastic resin outer jacket 28, as also described in more
detail below.
[0065] The hypotube 26 defines at least three longitudinal segments
of respective properties. In a preferred embodiment, the respective
properties are defined by laser cutting a functional design into
the hypotube; i.e., a lattice structure including longitudinal
spines 56, 58 and relatively perpendicular or transverse struts 52
of defined orientation and width that provide functional
characteristics along the length of the hypotube 26. Specifically,
a distal segment 34 is highly flexible and adapted to deflect in
any direction relative to the longitudinal axis across a frontal
plane; a central segment 36 is defines a particular curve and
orientation of flexure along its portion of the longitudinal axis
and returns to such curvature when the deflection force is removed;
and a proximal segment 38 defines mating structure adapted to
facilitate coupling the hypotube 26 to the braid 46 of the guiding
catheter 10. A leading arm segment 40 is preferably provided
between the central curvature segment 36 and the distal highly
flexible segment 34 and is designed to deflect with an intermediate
resistance along a single axis. A support segment 42 is preferably
provided between the central curvature segment 36 and the mating
segment 38, and is adapted to provide flexural support (deflection
resistance) when the relatively distal segments 34, 36, 42 are
under load. The various segments are defined with respective
patterns preferably laser cut into the hypotube, although the
patterns may be defined via a different method such as, e.g.,
chemical etching or mechanical cutting. The patterns described in
FIGS. 2 through 6 are illustrated as flat projected patterns, but
should be visualized as projected 360.degree. about the
circumference of the hypotube 26.
[0066] Turning now to FIG. 3, a first pattern 50 identifies the
pattern of areas of material to be removed from the hypotube, such
as by laser cutting; i.e., the negative space. The first pattern
defines a remainder of positive space in the form of the spines 56,
58 and the struts 52. The spines 56, 58 extend parallel to the
longitudinal axis of the hypotube. The struts 52 are longitudinally
displaced and laterally extending ribs, all oriented perpendicular
to the spines 56, 58. The pattern 50a at the distal segment 34
includes the narrowest struts 52a provided in an offset, or
interleaving, pattern. This aids in distal flexibility. The pattern
50c at the curvature segment 36 includes the widest struts 52c. The
pattern 50b at the leading arm segment 40 has struts 52b at an
intermediate width between the sizes of the struts 52a, 52c of the
distal and curvature segments. The pattern 50e at the proximal
mating segment 38 is patterned similarly to 50a of the distal
segment 34, but has wider struts 52e. The pattern 50d for the
support segment 42 defines struts 52d similarly arranged to the
curvature segment but at least a portion of the struts preferably
have zig-zag edging 54 provided along the long sides of the struts
52d. The zig-zag edging 54 aids in adhesion of the overlying and
underlying resin at the support segment 42. One spine 56 is shown
along the center of the pattern; the other spine 58 is defined
between the opposing ends of the struts as the pattern 50 is
projected onto and cut into the hypotube. The two spines 56, 58
extend through the support, curvature and leading arm segments,
with the spines 56, 58 widest at the curvature and support segments
36, 42 (e.g., 0.013 inch), and preferably tapering through the
leading arm segment 40 (0.0115 to 0.007 inch). The spines do not
extend through the patterns 50a, 50e of interleaving struts at the
distal and proximal mating segments 34, 38. In accord with the
first pattern 50, the struts have a symmetrical structure about the
spines such that hemi-tubular portions of the hypotube are the
same. FIG. 4 more particularly illustrates the pattern 50c of the
curvature segment and FIG. 5 shows a portion of hypotube 26 laser
cut with such pattern 50c and its behavior under torsion.
[0067] Turning to FIG. 6, a second pattern 150 includes struts 152
that are all oriented as perpendicular ribs relative to the spines
156, 158, but configured to bias the hypotube in a determined
orientation. The patterns for the distal, leading arm, support and
proximal mating segments 150a, 150c, 150d, 150e, as well as the
spine dimensions, are preferably the same or substantially similar
to that described in the first pattern 50. The curvature segment
150b includes asymmetric central struts 152b', 152'', in which one
hemi-tubular portion 160a has wider struts and its opposite
hemi-tubular portion 160b has narrower struts, thereby providing an
inherent bias to deflection and bending toward the hemi-tubular
portion 160b.
[0068] Referring to FIG. 7, a third pattern 250 includes distal and
proximal mating segments 250a, 250e and spine configurations that
are substantially as described, as in the first pattern 50.
However, the struts 252 at the leading arm, curvature and support
segments 250b, 250c, 250d are angled relative to the spines 256,
258 in a lattice arrangement. Specifically, referring to FIG. 8,
the lattice pattern of the struts 252 is defined by interlocked
struts extending in X-shaped arrangements between the spines 256,
258, with the struts meeting at joints 262 laterally between the
spines. In pattern 250, struts 252 are preferably widest at the
curvature and support segments 250c, 250d and reduced in width
toward and through the leading arm segment 250b. FIG. 9 illustrates
a portion of the hypotube 226 formed by the laser cut pattern 250
for the lattice arrangement in FIG. 8.
[0069] Turning to FIG. 10, a fourth pattern 350 includes distal and
proximal mating segments 350a, 350e and spine configurations that
are substantially as described as in the first pattern 50. The
struts 352 at the leading arm, curvature and support segments 350b,
350c, 350d are provided in a lattice arrangement, which is
generally wavy. Referring to FIG. 11, the wavy lattice arrangement
may be a pattern of longitudinally offset first and second struts
352a, 352b that extend perpendicularly from opposing spines 356,
358, third and fourth struts 352c, 352d that extend parallel to
each other and at an angle to the first and second struts, with the
first and third and second and fourth struts meeting at respective
first and second joints 362a, 362b, and a fifth strut 352e that
couples the first and second joints, the fifth strut transversely
oriented relative to the first, second, third and fourth struts,
and generally perpendicular to the second and fourth struts. FIG.
12 illustrates a portion of the hypotube 326 formed by the laser
cut pattern 350 of the lattice arrangement in FIG. 11. The struts
in such wavy lattice may have different sizes in different segments
or in different portions of a same segment. In the fourth pattern
350, the struts in the curvature segment 350c and support segment
350d are preferably larger than the struts in the leading arm
segment 350b. The struts in the wavy pattern transfer force applied
to the hypotube at an angle so that the spine deflects in
torsion.
[0070] Referring now to FIG. 13, a fifth pattern 450 is a hybrid
design having portions with both struts in a wavy lattice and
struts in a perpendicular rib-like arrangement. The fifth pattern
450 includes distal and proximal mating segments 450a, 450e and
spine configurations that are substantially as described as in the
first pattern. The struts in the support segment 450d are oriented
perpendicular to the spines 456, 458. The support segment 450d
includes a proximal portion 450d' with struts 452d' having zig-zag
edges, and a distal portion 450d'' with struts 452d'' having
straight edges. The leading arm segment 450b has struts 452b of
preferably uniform width also extending perpendicularly relative to
the spines 456, 458 but smaller than those in the support segment
450d. As shown in FIG. 14, the pattern for the curvature segment
450c defines, at a first hemi-tubular portion 460a, rib-like struts
452c' of preferably uniform width, though smaller than the struts
of the support segment 450d, extending perpendicular to the spines
456, 458 and, at a second opposing hemi-tubular portion 460b,
struts 452c'' in a wavy configuration as described above with
respect to the fourth pattern 350. Also, the struts may be larger
at a proximal end of the curvature segment 450c than at the distal
end thereof. FIG. 15 illustrates a curvature segment 450c of a
hypotube 426 formed by the laser cut pattern 450 shown in FIG. 14
and subject to torsion.
[0071] Turning now to FIGS. 16 and 17, with respect to each of the
patterns 50, 150, 250, 350, 450, the distal segment (e.g., 50a) is
structurally adapted for flexibility to allow the device to freely
track over a guidewire and provides a flexible atraumatic tip at
the distal end of the catheter 10. The cut pattern defines a
deflection plane 70 that is equally able to be deflected in any of
directions a, b, c, d (90.degree. apart), or in intermediate
directions, relative to the longitudinal axis A (FIG. 18). The
laser cut pattern provides both positive and negative space within
the hypotube 26 to allow for the resin of the outer jacket 28 to
evenly fill the negative space and provide adhesion between the
positive space and the underlying liner 31 (FIG. 2). Specifically,
the widths of defined struts in the distal segment 50a of the
hypotube are designed to allow the outer jacket resin to wick under
the hypotube 26 during the resin-coating process, described below,
which also results in the hypotube adhering to the liner 31 and
forming a cohesive device. Further, the spacing of the struts from
each other is designed to provide support to the distal segment
during pressurization.
[0072] The leading arm segment 50b, 150b, 250b, 350b, 450b, is
adapted to deflect with intermediate resistance (i.e., less than
the distal segment) along a single axis of a frontal plane. The
deflection plane is defined between the two spines, e.g., 56, 58.
The width of the spines 56, 58 governs resistance to deflection
along the frontal plane and retention of the set shape after
deflection. The spines 56, 58 may or may not provide flexural
support. In patterns where the spines do not provide flexural
support (e.g., patterns 50 and 150), the thickness of the wall of
the hypotube relative to the width of the spines should remain
within a 1:4 to 1:3 ratio in order to maximize spring force while
preventing buckling. The use of interconnected struts (e.g., as
shown in patterns 250, 350 and 450) can provide additional force
used to add deflection resistance and shape retention. In such
cases, adequate retention force can be supplied using members with
1:1 tube thickness/support width ratios. In general, the width of
the spines is a primary factor governing the resistance to
deflection and shape retention, while the thickness of the spines
is a determining characteristic in the stability of the hypotube
(resistance to buckling). A design with a 1:1 ratio of the hypotube
wall thickness to spine width will be more dimensionally stable,
but will not supply as much force as a design with a 1:2 or 1:3
ratio. The optimal hypotube wall thickness to spine width ratio is
also dependent upon the radius of curvature. In an exemplar device
comprising a hypotube with a 0.060 inch inner diameter and a 0.067
inch outer diameter (defining a 0.0035 inch wall thickness),
adequate resistance to deflection and good shape retention were
obtained on a 10 mm diameter curvature using 0.0135 inch wide
spines and struts in a rib pattern (patterns 50 and 150). As the
curvature diameter increases, the wall thickness to spine width
ratio can decrease to 1:5, 1:6 or even less without resulting in
buckling of the structure. In an alternative design using identical
tube geometry, the same deflection resistance and shape retention
can be achieved using an interlocked lattice pattern where the wall
tube thickness is 0.0035 inch, the spine width is 0.010 inch, and
the interlocking lattice elements are 0.002 inch to 0.006 inch in
width (patterns 250 and 350).
[0073] The leading segment 50b, 150b, 250b, 350b, 450b is also
designed to deflect along the central axis A (FIG. 2) under a
torsional force. Such deflection makes the leading segment
atraumatic during tracking and positioning within a vessel.
Deflection causes the torsional force to transfer into the hypotube
by distorting supporting structures and allowing the spines to
close in and wrap around each other. In patterns designed to
minimize deflection under torque, force is transferred in plane
around the radial axis. This builds up high amounts of stress until
local buckling of the structure occurs, shearing through the tube
and causing separation. In distinction, the hypotube at the leading
segment when subject to torsion is preferably designed to allow the
spines to fold over each other to the point of lumen collapse (at
370) (FIG. 19), preventing separation of the hypotube from the
remainder of the catheter. The superelastic characteristic of the
hypotube 326 allows the hypotube to return to shape once the
torsion is removed (FIG. 20).
[0074] The curvature segment is structured to retain its shape when
deflected along the central axis A through the frontal plane. The
spines 56, 58 of the hypotube 26 determine the direction of
deflection, with deflection occurring between the spines. The
widths of the spines 56, 58 govern resistance to deflection and
assist in retention of the set shape after deflection. As described
above with respect to the leading arm segment, the curvature
segment is adapted to deflect along central axis A when subject to
torsional force. Such deflection makes the curvature segment
atraumatic during tracking and positioning. The curvature segment
is also structured to allow the spines 56, 58 to fold over each
other at point of lumen collapse under torsion, preventing
separation of the hypotube. This ability to deflect and fold allows
the curvature segment to withstand torsional force without
separation from the remainder of the catheter.
[0075] Further, turning to FIG. 38, the curvature segment is
preferably designed to have an interlocked pattern of struts 22 on
the apex 618 of curvature to support resin (not shown). The
interlocked pattern may comprise a braced X-shaped arrangement 630
of the struts extending between the spines 56 (, 58). As the
hypotube 26 is shaped into its curved form, the spacings 23a
between the struts 22 on the apex 618 of curvature widen while the
spacings 23b at the underside 616 of the curvature relatively
narrow. The spacing between the struts needs to be controlled in
order to withstand adequate burst pressure, bearing in mind that
guide catheters are used to infuse contrast, sometimes under
significant pressure in order to fully visualize the anatomy. In a
typical construction in which the overall catheter wall thickness
is 0.007'' and the resin is composed of a low durometer, relatively
weak material, an acceptable range for the gap between the strut
elements is 0.001 inch to 0.020 inch. While this gap range can be
maintained in some cases by increasing the frequency of overlying
features, there is a practical design limit at which distortion due
to curvature prevents appropriate coverage of supporting metal
elements. One solution is with an interlocked pattern, such as
shown in patterns 250, 350, 450 in which at the respective
curvature segments 250c, 350c, 450c no single strut is separated
from another strut by more than a maximum determined gap size.
While individual struts stretch and spread, adequate overall
coverage is maintained.
[0076] A similar effect can be achieved by biasing the ratio of cut
and uncut material so that more hypotube material is preserved on
the apex of the curvature segment 150c than on the underside (FIG.
6). In one example, the hypotube includes 0.012-inch-wide rib-like
struts on the outer, exterior, convex (upper or apical) surface and
0.009 inch ribs on the inner, exterior, concave (lower) surface. If
the struts are spaced at 0.0025 inch intervals with a narrow
connection point as is shown in the rib design, the gap between
ribs on the upper surface would be approximately 0.013 inch and the
gap between ribs on the lower surface would be approximately 0.016
inch. When the device is curved, the gap on the upper surface
widens and that on the lower surface reduces, resulting in a final
device where gaps on both the upper and under surfaces are
approximately 0.014 inch.
[0077] As shown in patterns 150 and 450, the curvature segment
150c, 450c may also be designed to have a higher cut to uncut ratio
for the hypotube such that less hypotube material remains at the
lower surface. This feature may also be provided to modified
patterns 250 and 350, to provide lattice structures for the struts
that are thicker on the apical upper surface and thinner on the
lower surface. This promotes even resin filling when the curvature
segment is curved.
[0078] The support segment (e.g., 50d) has similar structural and
functional characteristics to the curvature segment, but may
optionally have a pattern adapted to increase its mechanical
interlock with resins to enhance bond force at a joint 500 between
the hypotube 26 and the braid 46. Specifically, the support segment
includes the same structures that provide the above-described
ability to deflect and fold and which thereby allow the hypotube to
withstand torsional force without separation from the remainder of
the catheter. Thus, it is appreciated that when a sufficient
torsion is applied over proximal and distal portions of the
hypotube, the hypotube deflects and folds, and then returns to
shape once the torsional force is removed.
[0079] Turning to FIGS. 21 and 22, the proximal mating segment 38
of the hypotube 26 is adapted to mimic the stiffness, axial
flexibility and kink performance of the proximal braid 46 of the
catheter. This allows the proximal mating segment 38 to transition
from the relatively distal segments of the hypotube 26 to the
remainder of the catheter. The proximal mating segment 38 is
designed to allow a high torque transfer from the relatively
proximal braid to the hypotube, as well as prevent buckling and
provide kink resistance. To do so the catheter (1) has reinforcing
materials on either side of the joint 500 between the hypotube 26
and braided portion 46 with similar mechanical behavior (kink
radius, column strength, deflection resistance, torque transfer);
(2) has a joint 500 comprised of three interdependent segments with
a defined kink radius and deflection force specification; (3)
defines a minimum separation gap between the reinforcing materials;
(4) has a joint with a rotational interlock between the braid and
hypotube; and preferably (5) utilizes continuous high strength
polymeric material for each of the inner liner 31 through the braid
and hypotube, and the outer jacket 28 over the braid and
hypotube.
[0080] Referring to FIG. 39A, in one manufactured form, the
hypotube 726 requires equal force to be bent in any direction. For
example, 25 grams of force may be required to push the hypotube in
each of four directions. Such a hypotube manufacture is shown in
FIG. 42, which has a strut layout generated from the laser cut
pattern 701 of FIG. 43. The pattern creates a longitudinally
repeated offset pattern of a plurality of, e.g. three,
`dogbone`-shaped openings 728 circumferentially cut in the hypotube
726.
[0081] However, turning now to FIG. 39B, the hypotube 726a of FIG.
39A and FIG. 42 can be biased to adopt a curved configuration. The
curve can be effected by altering the crystal structure of the
superelastic alloy of the hypotube (heat setting the alloy),
distorting an unbiased pattern to adopt a curved configuration.
This increases resistance to bending counter to the curved
configuration and reduces resistance when bending with the curved
configuration, as illustrated by the 50 grams of force required to
push the hypotube in a first direction and a zero grams of force
required to push the hypotube in an opposite second direction.
[0082] An unbiased configuration of the hypotube allows the
orientation of the hypotube (as part of the guiding catheter) to
autocorrect and self-orient if (1) the bending resistance in the
plane is adjusted by heat setting and (2) if the laser cut
structure allows the hypotube to be torqued along its axis. The
resistance to torque or rotate the tube should be less over the
portion of the hypotube that is curved than the force required to
bend the tube counter to the heat set shape. That is, for
autocorrection during guiding through the vessels, the hypotube
should be heat set such that its longitudinal axis extends along a
curved shape, with the hypotube possessing a rotational stiffness
such that the force required to torque the hypotube 180 degrees in
rotation is less than the resistance required to bend the hypotube
counter to the curved shape. For example, if the resistance to
bending a 1 cm long curve is 50 grams, the resistance for torquing
the tube 180 degrees over the tube length should be less than 50
grams.
[0083] Turning now to FIG. 40A, by placing stiffening spines or
struts 896 and 898 along the circumference of a hypotube 826, the
hypotube 826 can be constructed to limit bending within a single
plane. Referring to FIG. 40B, additionally heat-altering the
crystal structure of the superelastic alloy of the hypotube 826a
(heat setting the alloy), a biased pattern can be made to adopt a
curved configuration. This increases resistance bending counter to
the curved configuration and reduces resistance when bending with
the curved configuration.
[0084] Moreover, referring to FIG. 41A, a hypotube 926 can be
constructed with stiffening spine 996 at a single side, requiring
additional force to bend in a first direction (e.g., 40g) relative
to its opposite second direction (e.g., 20g). FIG. 44 shows a
portion of the hypotube 926 having a spine 996 with high resistance
to bending at one side, and a circumferentially opposing window 932
with low resistance to bending. FIG. 45 illustrates the laser cut
pattern 901 for generating the hypotube 926 of FIG. 44. Thus, when
the hypotube 926 tracking over a curved anatomical feature, the
hypotube bends readily only in the axis parallel to supporting
transverse struts 922. This is because the resistance to bending
perpendicular to the stiffening spine 996 is greater than bending
parallel to the stiffening struts 922, thus locally increasing
bending resistance in the direction of the stiffening segment.
Then, as shown in FIG. 41B, the hypotube 926a can be biased with
heat setting to further prefer bending to one side (60g relative to
zero grams).
[0085] Now referring back to FIG. 2, one aspect of the joint 500
between the hypotube 26 and the braid 46 includes matching
properties between the hypotube and the braid. For example, for a
braided catheter shaft with a kink radius of 3 mm with a flexural
modulus of 10 g/cm.sup.2, the proximal mating segment of the
hypotube matches these properties for a minimum of 3 mm in order to
form an interface that closely matches that of the braid. It should
be understood that the braid and hypotube pattern can be adjusted
to produce specified device properties in a controlled and
predictable manner.
[0086] Referring to FIGS. 23 and 24, the joint 500 comprises three
longitudinally arranged and interdependent joint segments that
together provide kink resistance. In order to achieve the high kink
resistance, a central joint segment 502 preferably has a length
corresponding to a target minimum kink radius, e.g., 3 mm. The
proximal and distal joint segments 504, 506, immediately proximal
and distal to the joint 500, preferably have a kink radius one-half
to two-thirds of the target radius with a flexural modulus one-half
to two-thirds that of the central segment. During bending centered
at the joint 500, the proximal and distal segments 504, 506 undergo
high deformation while the central segment 502 remains more rigid.
Force is deflected away from the central joint 502 as the proximal
and distal segments 504, 506 bend, but do not kink within the
specified target kink radius (FIG. 26).
[0087] In one embodiment of the catheter, these properties of the
joint 500 are achieved by varying the durometer of the elastomeric
resin forming the outer jacket 28 over the hypotube 26 and braid
46. The proximal and distal joint segments 504, 506 are jacketed in
a low durometer resin (60A to 55D durometer), while the central
joint segment 502 is jacketed in a higher durometer resin
(typically 10 to 60 durometer higher than proximal and distal
segments). The selective stiffening of the central joint segment
502 with a higher durometer resin results in a higher flexural
modulus than the proximal and distal joint segments 504, 506. The
length of the central joint segment 502 and the difference in
durometer between the resin utilized for the central segment 502 in
relation to the proximal and distal segments 504, 506 is then
adjusted to achieve the preferred properties.
[0088] The central joint segment 502 may be reinforced with a high
stiffness adhesive over a defined length. The joint is then covered
in an elastomeric resin tube or wrap 508. The stiffness and length
of adhesive jacket application can then be adjusted to achieve the
preferred properties.
[0089] In another embodiment of the device, a thin high durometer
tubular extrusion or wrap such as polytetrafluoroethylene (PTFE),
fluorinated ethylene propylene (FEP), perfluoroalkoxy (PFA),
ethylene tetrafluoroethylene (ETFE), polyethylene terephthalate
(PET), and/or polyetherether-ketone (PEEK) polymers can
additionally or alternatively be placed over the central joint
segment 502 prior to jacketing with an elastomeric resin. The
length, durometer, and thickness of this extrusion or wrap can be
adjusted to achieve the properties described above.
[0090] In order to minimize the separation gap between the hypotube
26 and the braid 46, which would function as a mechanical
discontinuity, one or more interlocking elements 510 extend from
the hypotube into spaces 512 defined at the ends of the braid 46
(FIG. 25). The one or more interlocking elements 510 interlock with
the braid 46 at the spaces 512 to transfer torque through the joint
500. In one embodiment, the interlocking elements are tabs machined
or laser cut from the hypotube to closely fit within spaces formed
at the end of the abutting braid. These space 512 can be defined by
the extension of the braid wires. The geometry of the tabs 510
should fall within the spacing of the braid wire to prevent the
hypotube 26 and braid 46 from overlapping. The outer jacket 508
extends over the joint 500, constraining movement during applied
torsion. The tabs 510 interlock with the end of the braid 46,
allowing the mechanical transfer of torque from the braid 46,
across the joint 500, and to the hypotube 26.
[0091] The continuous high strength polymeric materials used at the
inner lining 31 and outer jacket 508 reinforces the joint 500 and
allows for acceptable tensile strength and torque transfer
properties. The thickness of the inner lining 31 and/or outer
jacket 508 is determined by the intended kink resistance,
flexibility, and tensile strength of the device. The material is
designed to minimize thickness (and thereby minimize impact to kink
resistance and flexibility of the device) to achieve the required
tensile strength. In one embodiment, a thin continuous extrusion of
PTFE ranging between 0.00025 inch and 0.003 inch in thickness and
most preferably between 0.0005 inch and 0.0015 inch in thickness is
applied to the inner lumen of the device and defines the inner
lining 31. The braid 46 and hypotube 26 are positioned as described
above over this inner liner 31. The outer jacket 508 of
thermoplastic elastomeric material is then positioned over the
braid 46 and hypotube 26 and heated to join with the braid 46,
hypotube 26, and PTFE liner 31. A second continuous layer 514 of
high strength material such as PET is then preferably applied to
the outer jacket 28 of the device. The thickness of the second
layer 514 ranges between 0.0001 inch and 0.003 inch and most
preferably ranges from 0.00025 inch to 0.00075 inch in thickness.
The resulting device can achieve a kink resistance of 8 mm or less
and has a tensile strength of over 8 lbf.
[0092] In accord with one aspect of the catheter construction, the
polymeric jacket 28 is heat set onto the hypotube 26 such that at
least the axis of the curvature portion of the hypotube extends
along a curve, with the inner, smaller radius, concave (lower)
surface 616 of the hypotube curved under compression and the outer,
larger radius, convex (upper) surface 618 (along the apex side) of
the hypotube curved under tension (FIG. 35). The resin is
differentially heat set such that the resin at the lower surface of
the central curvature segment 36 along the hypotube is raised to a
temperature at or above the melting point of the resin, while the
resin at the upper surface of the central curvature segment 36 is
raised to a temperature below the melting point of the resin. The
resin on the lower surface is able to fluidize, relieving residual
compressive stress and distributing the resin evenly over the lower
surface. The resin at the upper surface does not melt, preventing
exposure of the underlying hypotube, as a resin under tension tends
to thin over the upper surface. However, the resin at the upper
surface is permitted to reach a plastic transformation temperature
that relieves tensile stress in the material.
[0093] In one method of differential heat setting the resin of the
jacket, heated air is utilized. The heating air is applied locally
to the lower surface. Referring to FIGS. 27 and 28, a system is
provided for directing the heated air to the lower surface for the
heat setting procedure. The system includes a nozzle 602, a holder,
preferably in the form of a shaping plate 604, and preferably a
mount 606 that stably receives and orients and the plate. The
nozzle 602 includes perforations 608 ranging in size between 0.0005
inch and 0.015 inch in diameter. The holder 604 includes an opening
610 and a channel 612 sized to accommodate the distal
shape-retentive section 24 at the distal end of the guiding
catheter 10 (FIG. 29). Referring to FIGS. 30 and 31, the channel
612 defines a path in the shape at which the shape-retentive
section is to be heated, with such path extending about the opening
610. Section 24 of the catheter is placed into the channel, with
the central curvature segment 36 of the hypotube 26 aligning with
the corresponding portion of the path and extending about the
opening 610. The holder 604, with distal shape-retentive section 24
positioned therein, is then inserted into the mount 606. Referring
back to FIG. 28, the nozzle 602 and holder 604 are then positioned
relative to each other such that the nozzle 602 is positioned
within the opening 610 of the holder, preferably without contacting
the holder 604 or the catheter 10.
[0094] Referring to FIG. 34, air 614 is then passed through the
nozzle 602 and out of the perforations 608. As air passes through
the perforations 608, an even zone of heated air is produced. The
air temperature forms a gradient with higher temperatures nearer
the perforated nozzle 602 and lower temperatures extending away
from the nozzle. This gradient is defined by mathematical modeling
such as Newton's Law of Cooling. Therefore, the system is designed
and operated in a manner where the temperature on the lower surface
616 of the curving segment 24 (and closest to the nozzle) reaches
the melting point of the resin at a fixed distance from the
perforated surface (Du) while the temperature drops below the
melting point of the resin on the upper surface 618 of the curving
segment over the distance of the diameter of the catheter
(Du+Diametercatheter). After air heating, the catheter 10 is
allowed to cool, and then removed from the holder 604, as shown in
FIG. 35, with the intended shape retained.
[0095] In another method of differentially heat setting the resin
outer jacket 28, radiant energy is used. The radiant energy is
applied to melt the lower surface 616 while allowing the resin at
the upper surface 618 to plastically deform. In an embodiment, an
electrically heated element of fixed geometry is used within the
opening of the holder of the system to perform the radiant heat
setting operation. The radiant energy intensity near the element is
higher than that farther from the element. The gradient of the
radiant energy is predicted using mathematical models such as
Newton's Inverse Square Law. Therefore, the system is designed and
operated in a manner where the temperature on the lower surface 616
reaches the melting point of the resin at a fixed distance from the
radiant surface (Du) while the temperature drops below the melting
point of the resin on the upper surface 618 over the distance of
the diameter of the catheter (Du+Diametercatheter).
[0096] As such, the gradient of heat over a specified distance and
the transfer of heat into the resin relative to temperature and
time can be modeled mathematically in both heating methods, and the
heating apparatus takes such parameters into account by including a
timing function that limits the duration of exposure to the
heat.
[0097] In both of these cases, the resin on the lower surface 616
fluidizes, fully relieving the residual compressive stress existing
in the resin beforehand, shown by the folds 620 at the lower
surface 616 of the pre-treated catheter 10 in FIG. 36, and
distributing the resin evenly over the lower surface 616 in the
post-treated catheter shown in FIG. 37. The resin on the upper
surface 618 does not melt and fluidize. This prevents exposure of
the underlying hypotube 26 as the resin under tension tends to thin
over the upper surface. Based on the gradient formed by the
convective or radiant elements, the resin is allowed to reach the
plastic transformation temperature where the tensile stress can be
relieved by plastic deformation.
[0098] The resin jacket 508 is preferentially made of a polymer
acting in a primarily elastic manner in the room temperature to
body temperature range. The resin is also preferentially made of a
thermoplastic material (one that can move or fluidize at elevated
temperatures) as opposed to a thermoset (a material with polymer
crosslinking or otherwise cannot be fluidized by elevated
temperatures).
[0099] Where radiopacity is required, the resin may be loaded with
radiopacifying agents such as barium sulfate (BaSO.sub.4), bismuth
oxide (Bi.sub.2O.sub.3), or metallic powders such as tungsten.
[0100] Turning now to FIG. 46, the guiding catheter 10 is shown in
its at rest position with shaped with two curved regions at its
distal end, a distal curve 90 and a primary curve 92. FIG. 47 shows
the guiding catheter 10 straightened for insertion into a delivery
catheter and through vessels, such that the distal end adopts an
S-shape.
[0101] Referring to FIGS. 48 through 50, in a method, the guiding
catheter 10 is tracked over a guidewire 88 into an anatomical arch
89 (such as the iliac arch). It is often easier to position the
guidewire 88 over the arch 89 into the descending vessel 91 when
the distal curve 90 of the guiding catheter conforms to the curve
of the arch. However, if inserted in this manner, the guiding
catheter 10 will follow the path of the distal curve 90, causing
the hyperextension at 92a (bending backwards) of the primary curve
92. The guiding catheter cannot properly configure in this
orientation. Therefore, to correctly reorient the device, the
device must be rotated by 180 degrees. Once the rotation is
effected, the required shape is formed and the catheter 10 can be
advanced according to standard procedure.
[0102] Turning to FIGS. 51 and 52, in another method, the guiding
catheter 10 can be tracked over a guidewire 88 through the
anatomical arch 89 and initially in the correct orientation by
tracking with the distal curve 90 pointed upward during
advancement. In this manner, hyperextension of the primary curve 92
through the arch 89 is prevented and there is no need to rotate the
guiding catheter 10 to correctly orient it within the descending
vessel 91 (FIG. 52).
[0103] Both of the prior methods can be carried out with a catheter
having a hypotube with a biased-spine construct using the
aforementioned biasing techniques (either with stronger struts or
heat-set struts, e.g., as shown in FIGS. 40A and 40B).
[0104] However, using a catheter having a hypotube with a
non-biased spine construct (such as shown in FIG. 39A) or with a
construct having a gradient of forces (such as shown in FIG. 39B),
the device can be tracked over the arch in any direction; however,
the gradient of forces will result in a rotation of the device to
minimize force and position the primary curvature in confirmation
with the arch. Similarly, the design shown in FIGS. 41A and 41B
will also autocorrect in shape. 52
[0105] There have been described and illustrated herein embodiments
of a catheter and methods of manufacturing the catheter. In
addition, while embodiments of a pattern-cut elastic tube, which is
more preferably superelastic and in the form of a hypotube, is
described for use in catheter, it is recognized that the elastic
tube has utility beyond use in a catheter and can be used in other
medical devices, including, by way of example only, guidewires,
vascular treatment devices, endoscopic instruments, neurological
treatment devices, and many other devices. While particular
embodiments of the invention have been described, it is not
intended that the invention be limited thereto, as it is intended
that the invention be as broad in scope as the art will allow and
that the specification be read likewise. It will therefore be
appreciated by those skilled in the art that yet other
modifications could be made to the provided invention without
deviating from its scope as claimed.
* * * * *