Proximally tapered guidewire tip coil

The disclosure is directed to a guidewire having an elongate core member with at least one distally tapered portion at the distal section, with a flexible body member disposed around said distal section. The flexible body member is preferably comprised of a metallic helical coil that has proximally tapered portion at the proximal end, with a diameter similar to the outer diameter of the elongate core member at the point of attachment thereto. The distal end of the flexible body member is attached to the distal end of the elongate core member. The proximal taper of the flexible body member provides a smooth transition from the elongate core member to the flexible body member while minimizing the amount of bonding material needed and the resulting localized stiff portion at the point of connection between the proximal end of the flexible body member and the elongate body member.

BACKGROUND 
This invention relates to the field of guidewires for advancing 
intraluminal devices such as stent delivery catheters, balloon dilatation 
catheters, atherectomy catheters and the like within body lumens. 
In a typical coronary procedure a guiding catheter having a preformed 
distal tip is percutaneously introduced into a patient's peripheral 
artery, e.g. femoral or brachial artery, by means of a conventional 
Seldinger technique and advanced therein until the distal tip of the 
guiding catheter is seated in the ostium of a desired coronary artery. 
There are two basic techniques for advancing a guidewire into the desired 
location within the patient's coronary anatomy, the first is a pre-load 
technique which is used primarily for over-the-wire (OTW) devices and the 
bare wire technique which is used primarily for rail type systems. 
With the pre-load technique, a guidewire is positioned within an inner 
lumen of an OTW device such as a dilatation catheter or stent delivery 
catheter with the distal tip of the guidewire just proximal to the distal 
tip of the catheter and then both are advanced through the guiding 
catheter to the distal end thereof. The guidewire is first advanced out of 
the distal end of the guiding catheter into the patient's coronary 
vasculature until the distal end of the guidewire crosses the arterial 
location where the interventional procedure is to be performed, e.g. a 
lesion to be dilated or a dilated region where a stent is to be deployed. 
The catheter, which is slidably mounted onto the guidewire, is advanced 
out of the guiding catheter into the patient's coronary anatomy by sliding 
over the previously introduced guidewire until the operative portion of 
the intravascular device, e.g. the balloon of a dilatation or a stent 
delivery catheter, is properly positioned across the arterial location. 
Once the catheter is in position with the operative means located within 
the desired arterial location, the interventional procedure is performed. 
The catheter can then be removed from the patient by sliding it back over 
the guidewire. Usually, the guidewire is left in place for a period of 
time after the procedure is completed to ensure re-access to the arterial 
location if it is necessary. For example, in the event of arterial 
blockage due to dissected lining collapse, a rapid exchange type perfusion 
balloon catheter such as described and claimed in U.S. Pat. No. 5,516,336 
(McInnes et al), can be advanced over the in-place guidewire so that the 
balloon can be inflated to open up the arterial passageway and allow blood 
to perfuse through the distal section of the catheter to a distal location 
until the dissection is reattached to the arterial wall by natural 
healing. 
With the bare wire technique, the guidewire is first advanced by itself 
through the guiding catheter until the distal tip of the guidewire extends 
beyond the arterial location where the procedure is to be performed. Then 
a rail type catheter, such as described in U.S. Pat. No. 5,061,395 (Yock) 
and the previously discussed McInnes et al. which are incorporated herein 
by reference, is mounted onto the proximal portion of the guidewire which 
extends out of the proximal end of the guiding catheter which is outside 
of the patient. The catheter is advanced over the guidewire, while the 
position of the guidewire is fixed, until the operative means on the rail 
type catheter is disposed within the arterial location where the procedure 
is to be performed. After the procedure the intravascular device may be 
withdrawn from the patient over the guidewire or the guidewire 
repositioned within the coronary anatomy for an additional procedure. 
Further details of guidewires, and devices associated therewith for various 
interventional procedures can be found in U.S. Pat. No. 4,748,986 
(Morrison et al.); U.S. Pat. No. 4,538,622 (Samson et al.): U.S. Pat. No. 
5,135,503 (Abrams); U.S. Pat. No. 5,341,818 (Abrams et al.); and U.S. Pat. 
No. 5,345,945 (Hodgson, et al.) which are hereby incorporated herein in 
their entirety by reference thereto. 
Conventional guidewires for angioplasty, stent delivery, atherectomy and 
other vascular procedures usually comprise an elongate core member with 
one or more tapered sections near the distal end thereof and a flexible 
body member such as a helical coil or a tubular body of polymeric material 
disposed about the distal portion of the core member. A shapable member, 
which may be the distal extremity of the core member or a separate 
shapeable ribbon which is secured to the distal extremity of the core 
member extends through the flexible body and is secured to the distal end 
of the flexible body by soldering, brazing or welding which forms a 
rounded distal tip. Torquing means are provided on the proximal end of the 
core member to rotate, and thereby steer, the guidewire while it is being 
advanced through a patient's vascular system. The leading tip is highly 
flexible and will not damage or perforate the vessel and the portion 
behind the distal tip is increasingly stiff which better supports a 
balloon catheter or similar device. 
In an ordinary guidewire, the flexible body member is of constant diameter 
and is of greater diameter than the core member to which it is being 
attached. The attachment method normally comprises a welding, soldering or 
brazing process, or some other bonding process which might include the use 
of adhesives, or mechanical means. The solder, braze, or weld material is 
applied to the flexible body and the core in sufficient quantity to effect 
a solid joint between the two elements. 
A problem inherent in this design is that the body of solder required to 
secure the helical coil at the bond disrupts the flexibility, i.e., there 
is a stiff spot which prevents a smooth transition. The present invention 
solves these and other problems. 
SUMMARY 
The present invention is directed to an improved guidewire which has a 
smooth transition at the bond of the proximal end of the flexible body to 
the core member. This allows for smoother bends in the guidewire and 
easier tracking and translation of devices that slide over the guidewire. 
The guidewire of the present invention has an elongated core member which 
has a distal section and a proximal section. Preferably, the distal 
section of the core has at least one tapered portion that tapers in a 
reduced diameter towards the distal end of the device. A flexible body 
member, for example, a helical coil or polymeric tubular member, is 
disposed around at least part of the distal section of the elongate core. 
In accordance with the present invention, the proximal end of the flexible 
body member is tapered in the proximal direction to more closely 
approximate the diameter of the core member to which it is attached in 
order to reduce the amount of bonding material necessary to form the 
joint, and to make for a smoother joint transition. These and other 
advantages of the invention will become more apparent from the following 
detailed description of the invention when taken in conjunction with the 
accompanying exemplary drawings.

DETAILED DESCRIPTION OF THE INVENTION 
FIG. 1 depicts a guidewire 10 which is an embodiment of the invention which 
has an elongate core member 12 with a proximal section 14 and a distal 
section 16. The distal section 16 of the elongate member has at least one 
distally tapered portion 18. A flexible body member 20 is disposed around 
the distal section. The flexible body member 20, which has a proximal end 
22 and a distal end 24, and which has a proximally tapered section 25 is 
attached to the elongate core member at both its proximal end 22 and 
distal end 24. Preferably, the proximally tapered section 25 of the 
flexible body member is configured to have an inner diameter similar to 
the outer diameter of the elongate core member at the point of attachment 
of the proximal end of flexible body member. 
FIG. 2 is a cross sectional view of the guidewire of FIG. 1 taken at 
section 2--2, and shows a substantially circular cross section of the 
elongate core member 12, and a layer of lubricious coating 26. FIG. 3 
shows a cross sectional view of the guidewire of FIG. 1 taken at section 
3--3, and depicts the flexible body member 20 and a flattened distal end 
of the elongate core member 30 disposed within the flexible body member 
20. 
The elongate core member 12 is typically comprised of metal, preferably 
stainless steel or a nickel titanium alloy or a combination thereof, but 
can also consist of any material that yields the approximate mechanical 
properties of the named metals so long as the material is sufficiently 
biocompatible. Other materials such as high strength alloys, may also be 
used for the core member, either alone, or in combination with other 
materials such as those previously mentioned. The proximal section of the 
core member 14 and any portion of the core member not covered by the 
flexible body member 20 may optionally be used with a lubricious coating 
26 such as a flouropolymer, eg. TEFLON.RTM. by DuPont. It may also be 
coated with a silicone based coating, such as MICROGLIDE.TM. coating used 
by the present assignee, Advanced Cardiovascular Systems, Inc. on many of 
its commercially available guidewires. Other similar coatings, for 
example, hydrophylic coatings, or a combination of any of the above 
mentioned coatings may also be used. 
The core member 12 preferably has a substantially circular cross section 
throughout its length, save the distal end which optionally may be 
flattened into a ribbon 30 having a generally rectangular shaped 
transverse cross section to facilitate manual shaping by the guidewire 
user. 
The distal section 16 of the elongate core can be from about 0.39 inches (1 
cm) to about 11.8 inches (30 cm), preferably about 0.79 inches (2 cm) to 
about 5.9 inches (15 cm) and has at least one tapered portion 18, tapered 
distally. In FIG. 1, the distal section of the elongate core 16 has one 
distally tapered portion 18 leading to the distal end of the elongate core 
30 which may or may not be flattened. The distally tapered portion 18 of 
the distal section can be from about 0.39 inches (0.5 cm) to about 5.9 
inches (15 cm) in length, preferably about 0.79 inches (2 cm) to about 3.9 
inches (10 cm) in length, and most preferably about 2.3 inches (6 cm) to 
about 3.1 inches (8 cm) in length. The angle of the distally tapered 
portion 18 can be from about 0.1.degree. to 10.degree., preferably about 
0.1 to 3.degree. and most preferably about 0.11 to 0.15.degree.. 
The distally tapered portion or portions 18 of the distal section 16 of the 
elongate core member are preferably formed in the elongate core by 
centerless grinding but they may be made in a variety of ways, including 
hammer forging, chemical etching, laser machining or casting. 
The diameter of the proximal section 14 of the elongate core is about 0.01 
inches (0.25 mm) to about 0.045 inches (1.1 mm), preferably about 0.012 
inches (0.30 mm) to about 0.018 inches (0.46 mm), and most preferably 
about 0.013 inches (0.33 mm) to about 0.015 inches (0.38 mm). The distal 
end 30 of the elongate core, which may or may not be flattened, has a 
cross sectional diameter of about 0.001 inches (0.025 mm) to about 0.006 
inches (0.15 mm), preferably about 0.0015 inches (0.038 mm) to about 0.003 
inches (0.076). The length of the elongate core member 12 as a whole is 
about 35 inches (90 cm) to about 118 inches (300 cm), preferably about 59 
inches (150 cm) to about 89 inches (225 cm), and most preferably about 75 
inches (190 cm). 
The flexible body member 20 is disposed around all or part of the distal 
section 16 of the elongate core member, and has a distal end 24 and a 
proximal end 22. The flexible body member 20 can be comprised of many 
suitable materials that allow for increasing the diameter of the guidewire 
in the distal section without adding substantial stiffness to that 
section. Suitable materials include polymers, composites, and metals. 
Preferably the flexible body member 20 is comprised of a helical shaped 
metallic coil, more preferably a metal or composition of metal or alloys 
with some degree of radiopacity in order to facilitate flouroscopic 
viewing of the device while in use. Metals suitable for the flexible body 
member 20 may include gold, platinum, tantalum, stainless steel, and 
nickel titanium alloys, MP35N, or a combination or alloy of any of the 
foregoing. A flexible body member 20 comprised of metallic helical coils 
is typically comprised of coil winding material 32 that can have a cross 
sectional diameter of about 0.001 inches (0.025 mm) to about 0.008 inches 
(0.20 mm), preferably about 0.002 inches (0.05 mm) to about 0.004 inches 
(0.1 mm). 
As shown in FIG. 1, the flexible body member 20 of the presently preferred 
invention has a proximally tapered section 25, ending in a proximal end 22 
with an inner diameter similar to the outer diameter of the elongate core 
member at the point of proximal connection between the two. Such a 
configuration allows the two members to be connected with a minimum amount 
of bonding material at the proximal connection, which makes for a smoother 
and more continuous transition, and avoids stiff spots in the guidewire 
resulting from an accumulation of solder or other bonding material at the 
bonding site. 
The proximally tapered portion 25 of the flexible body member provides for 
a smoother transition from the elongate core member 12 to the flexible 
body member 20. The smoother transition allows the devices which are 
guided by the guidewire device to track more easily over the guidewire. 
FIG. 4 shows an enlarged view in partial section of a part of the distal 
section 16 of the guidewire 10 of FIG. 1. The flexible body member 20 is 
typically attached to the elongate core member 12 at its distal end 24 and 
its proximal end 22 by a suitable means such as soldering, brazing, or 
welding. Alternately, an adhesive bond using epoxy or cyanoacrylate could 
be used. The bonding material 58 can serve to further smooth the 
transition from the elongate core to the flexible body member. 
The taper angle 34 of the proximally tapered section 25 of the flexible 
body member is the angle the tangent to the tapered section makes with the 
longitudinal axis of the flexible body member, can be from about 0.1 to 
10.degree., preferably about 0.5 to 2.degree.. The flexible body member 20 
normally has a distal segment of substantially constant outer diameter 36, 
however, the proximally tapered section 25 of the flexible body member can 
extend over the entire length of the flexible body member 20. The distal 
end 24 of the flexible body member typically has an outer diameter 
approximately equal to the nominal outer diameter of the proximal section 
of the elongate core member and both diameters can vary with a maximum 
depending on the inner diameter of the lumen through which the guidewire 
must pass. Preferably, the nominal outer diameter of the flexible body 
member 20 is about 0.01 inches (0.25 mm) to about 0.05 inches (1.27 mm), 
more preferably about 0.012 inches (0.30 mm) to 0.018 inches (0.46 mm), 
and most preferably about 0.013 inches (0.33 mm) to about 0.015 inches 
(0.38). 
FIG. 5 illustrates another embodiment of the invention similar to that 
depicted in FIG. 1 but further comprising a shapeable separate ribbon 
member 38 disposed between the distal section 16 of the elongate core 
member and the flexible body member 20. The shapeable ribbon member 38 has 
a proximal end 40 which is attached to the elongate core member 12 by a 
body of solder 60, and a distal end 42 which is attached to the distal end 
of the flexible body member 24 by a body of solder 58, and is typically 
comprised of flattened metallic wire, such as stainless steel, nickel 
titanium alloy or other suitable metal. The length of the shapeable ribbon 
member 38 can be about 0.039 inches (1 mm) to about 1.18 inches (30 mm), 
preferably about 0.39 inches (10 mm) to about 0.79 inches (20 mm). The 
cross section of the shapeable ribbon member 38 can be about 0.0005 inches 
(0.013 mm) by about 0.010 inches (0.25 mm), preferably about 0.001 inches 
(0.025 mm) by about 0.003 inches (0.075 mm). 
FIG. 6 depicts another embodiment of the invention wherein the distal 
section 16 of the elongate core member has a first tapered core segment 44 
and a second tapered core segment 46. In this embodiment, the proximal end 
22 of the flexible body member is attached to the elongate core member on 
the second tapered core segment 46 by a body of solder 58, but could also 
extend and be attached to the first tapered core segment 44. The distal 
end 24 of the flexible body member is attached to the elongate core member 
at its distal extremity 48. 
The embodiment of FIG. 6 further comprises a first taper angle 50, which 
can be about 0.05.degree. to about 10.degree., preferably about 
0.1.degree. to about 2.degree., and a second taper angle 52, which can be 
about 0.05.degree. to about 10.degree., preferably about 0.2.degree. to 
about 3.degree., with the second taper angle 52 preferably greater than 
the first taper angle 50. Though two tapered core segments are shown in 
FIG. 6, any number of tapered segments can be used, with the taper angle 
each tapered segment being greater than the taper angle of the tapered 
segment located immediately proximal to it. 
The length of the first tapered core segment 44 can be about 0.39 inches (1 
cm) to about 5.9 inches (15 cm), preferably about 1.18 inches (3 cm) to 
about 1.97 inches (5 cm). The length of the second tapered core segment 46 
can be about 0.39 inches (1 cm) to about 5.9 inches (15 cm), preferably 
about 1.18 inches (3 cm) to about 1.97 inches (5 cm). Typically, the 
length of the second tapered core segment 46 is greater than the first. 
The flexible body member 20 of FIG. 6 is similar to that of FIG. 1, as are 
the distal end 30 and proximal section 14 of the elongate core member. 
The device as shown in FIG. 7 is another embodiment of a flexible body 
member 20 having a proximal end 22 and a distal end 24 with a proximally 
tapered section 25. This embodiment of the flexible body member 20 is 
comprised of a helical coil. The proximally tapered section 25 is a 
gradual taper and terminates at the proximal end 22 in a proximal stack 54 
wherein the coils of the body are wound closely together so as to touching 
or in close proximity to adjacent coils. A similar configuration exists at 
the distal end 24 where the distal end terminates in a distal stack 56. 
The purpose of the distal stack 56 and proximal stack 54 is to improve the 
joint of the coil 20 to the second tapered core segment 46. The length of 
the proximal stack 54 and distal stack 56 is from about 0.05 mm to about 1 
mm. The coils of the flexible body member between the proximal stack 54 
and the distal stack 56 are loosely wound with adjacent coils spaced from 
each other. The outer diameter of the distal end 24 of the flexible body 
member can be about 0.006" to about 0.05", preferably about 0.012" to 
about 0.016". 
The taper angle 34 of the embodiment of the flexible body member shown in 
FIG. 7 is similar to that of the previous embodiments, as are the lengths 
of the proximally tapered section 25 and the distal segment of 
substantially constant diameter 36. The length of the flexible body member 
20 can be about 0.39 inches (1 cm) to about 11.8 inches (30 cm), 
preferably about 1.97 inches (5 cm) to about 7.9 inches (20 cm). The 
proximally tapered section 25 of the flexibly body member can be about 
0.039 inches (1 mm) to about 11.8 inches (300 mm), preferably about 0.2 
inches (5 mm) to about 4 inches (100 mm). While particular forms of the 
invention have been illustrated and described, it will be apparent that 
various modifications can be made without departing from the spirit and 
scope of the invention. Accordingly, it is not intended that the invention 
be limited, except as by the appended claims.