Steerable guide wire

A steerable guide wire for use in a medical procedure, such as coronary angioplasty, which requires positioning a catheter or other device at a remote location within the body by way of the cardiovascular system or other passage way. The guide wire has a solid core wire which runs the entire length. The distal end of the core wire is tapered to an intermediate diameter to permit insertion into a short flexible coil, or a combination of a flat wire coil and round wire coil attach to each other at a brazed joint. The flexible coil has an outside diameter approximately equal to the outside diameter of the core wire proximal to the taper. The proximal end of the flexible coil is fixedly attached to the taper. The distal tip of the core wire is further tapered and optionally flattened to enhance the handling characteristics as well as flexibility. The distal tip of the core wire and a flexible round wire coil are coextensive, and attached distally to form a smooth tip for the guide wire. The entire guide wire can be coated with a polymer or other suitable material to control, and reduce friction over the length of the guide wire.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates generally to devices for use in medical 
procedures, and more particularly, relates to guide wires for directing a 
catheter or other medical device through the cardiovascular system or 
other passage way in the human body. 
2. Description of the Prior Art 
Guide wires for positioning various medical devices within the body have 
been known for some time. A common current application for guide wire is 
in percutaneous translumenal coronary angioplasty (PTCA). In this 
procedure, it is often necessary to steer a guide wire from an entry point 
in the arterial system, such as the femoral artery, to the site of 
occlusion of a coronary artery. A dilatation catheter can then be easily 
advanced over the guide wire to the treatment site. 
In PTCA applications, it is necessary that the guide wire have a small 
diameter, be flexible enough to negotiate the tortuous arterial pathways 
without danger of perforation, and have sufficient steerability to permit 
the attending physician to select the desired pathway from a number of 
alternatives as branches in the arterial system are encountered. The ideal 
guide wire must have a flexible and bendable tip, along with the ability 
to evenly transmit torque from the proximal end to the distal end. 
U.S. Pat. No. 4,545,390, issued to Leary shows a typical design of a guide 
wire for PTCA applications. In the Leary guide wire, the central core wire 
terminates short of the distal tip. The result is that the guide wire will 
tend to bow at the distal tip upon application of longitudinal force. U.S. 
Pat. No. 4,763,647, issued to Gambale, shows a similar design with an even 
shorter central core wire. 
SUMMARY OF THE INVENTION 
The general purpose of the present invention overcomes the problems found 
in the prior art by providing a small diameter guide wire, which is 
flexible yet steerable while providing greater safety and the desired 
trackability. These features are obtained through the use of a solid core 
wire which extends the entire length of the guide wire. Near the distal 
end, the core wire has a first taper from the main diameter to an 
intermediate lesser diameter. At the distal tip, the core wire has a 
second taper from the intermediate lesser diameter to the smaller distal 
diameter. Optionally, the distal tip of the core wire may be flattened to 
enhance the flexibility. 
A short coil spring, having an outside diameter approximating the main 
diameter and an inside diameter longer than the intermediate diameter, is 
positioned over the distal end of the core wire. The coil spring is 
fixedly attached at its proximal end to the first taper of the core wire. 
The length of the coil spring is chosen such that when attached at its 
proximal end, it is coextensive with the distal tip of the core wire. The 
distal tips of the coil spring and the core wire are welded together to 
form a smooth hemispherical tip for the guide wire. 
The entire guide wire may be coated with a polymer or other flexible 
coating. The proximal end of the guide wire is configured to correspond to 
the particular application. For PTCA use, the proximal end permits 
insertion of the dilation catheter after the guide wire has been properly 
positioned.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
FIG. 1 is a plan view of a guide wire 10 incorporating the present 
invention, which has been partially sectioned to show the details of the 
construction and the operation. The inner element of guide wire 10 is a 
core wire 12 which is preferably a solid wire of 304 stainless steel or 
other similar material suitable for acute use in the human body. It is 
approximately 180 cm. in length between points A to F for PTCA 
applications by way of example and for purposes of illustration only, and 
not to be construed as limiting of the present invention. Core wire 12 may 
have proximal end 36 configured as is appropriate for the application such 
as hemispherical proximal end 40 in a diameter range of 0.012 to 0.018 
inches. 
The main body of core wire 12 is approximately 150 cm length between points 
A to B of a total length of 180 cm, and has a constant main diameter 14 of 
about 0.12-0.018 inch. From the main body diameter 14, the diameter 20 
next first tapers over about 2 cm distance between points B-C. An 
intermediate diameter 15 is substantially constant between points C-D. The 
diameter 16 further secondly tapers over a 4-15 cm distance from points 
D-E. The final diameter optionally resembles the cross section of FIG. 2 
over a distance of about 2 cm between points E-F. The distance between 
points B-F is about 30 cm. Beginning about 5-15 cm from the distal tip of 
core wire 12, the diameter tapers along distance 16 to the smallest distal 
diameter 22 of about 0.003 inch. Optionally and preferably, the most 
distal 2 cm of core wire 12 between points E-F may be flattened at 32 to 
reduce the stiffness and achieve greater flexibility. 
A flat wire coil 38 can be in intimate contact with the first tapered 
diameter 20 and is brazed to the core wire at each end at 28 and 44. 
A flexible coil spring 24 attaches to about the most distal 5 cm of core 
wire 12. The flexible coil spring 24 has an outside diameter of about 
0.012 to 0.018 inch and an inside diameter of about 0.010-0.012 inch. The 
most proximal portion 26 of coil spring 24 is tightly wound, and attaches 
to the core wire 12 by the brazed joint 28. The most distal portion 30 of 
the coil spring 24 is more loosely wound to improve the flexibility of the 
distal tip. At the distal end, coil spring 24 and core wire 12 are 
coextensive. These two components are fixedly attached by the 
hemispherical weld 34 which provides a smooth distal tip for insertion and 
maneuvering of the guide wire 10. 
The main body of core wire 12 along main diameter 14 may be optionally 
covered with a polymer 42 to improve handling characteristics. In the 
preferred embodiment, this is a polymer coating of PTFE, MDX, or any other 
suitable coating of about 0.0005 inch. Optionally the most distal 4 cm may 
be left uncoated as illustrated. Preferably, the most proximal end of 2-3 
cm is also left uncoated as illustrated in the figure. 
FIG. 2 is a cross sectional view of the distal tip of core wire 12 as 
optionally flattened along length 32. Such flattening of core wire 12 
provides increased flexibility. After flattening, core wire 12 along 
length 32 has cross sectional dimensions of about 0.002 by 0.0045 inch. 
The coil 24 is also made of radiopaque material. 
FIG. 3 illustrates a table for the diameter and the length for each section 
of the guide wire 10. 
MODE OF OPERATION 
The guide wire 10 of the present invention is utilized in medical 
procedures in accordance with generally accepted medical practices. 
Having thus described the preferred embodiments of the present invention, 
those of skill in the art will be readily able to apply the teachings 
found herein to other embodiments within the scope of the claims hereto 
attached.