Steerable medical device

An elongate steerable implement is disclosed, which may be either a steerable guidewire or catheter for coronary angioplasty applications. A floppy steerable tip on a steering region at the distal end of the implement and a control device at the proximal end are connected by means of a plurality of axially movable deflection wires extending throughout the implement. Manipulation of the control permits deflection of the steering region throughout a full 360.degree. range of motion about the axis of the implement, without axial rotation or "torquing" thereof. In another embodiment, a steering ribbon is disclosed which permits steering by lateral deflection of the tip into a deflected or bent position and then permits straightening the tip back to its original position.

The present invention relates to steering devices such as may be used with 
catheters, cannulae, guidewires and the like. More particularly, the 
present invention relates to catheters and guidewires that are steerable 
through body lumen or cavities and positionable within or aimable at 
obstructions, organs or tissue within the body from a position external to 
the body. 
Medical catheters generally comprise elongate tube-like members which may 
be inserted into the body, either percutaneously or via a body orifice, 
for any of a wide variety of diagnostic and therapeutic purposes. Such 
medical applications frequently require use of a catheter having the 
ability to negotiate twists and turns, particularly with regard to certain 
cardiovascular applications. 
One such application, "Percutaneous Transluminal Coronary Angioplasty" 
(balloon angioplasty), requires manipulation of a catheter from a position 
outside the patient's body through extended portions of the patient's 
arterial system to the stenotic site for the purpose of alleviating the 
obstruction by inflating a balloon. This particular procedure has been 
performed with increasing frequency over the past years in preference to 
open heart bypass surgery, when possible. 
In a typical angioplasty procedure, a guidewire is transluminally inserted 
into the brachial or the femoral artery, to be positioned within the 
stenotic region and followed by a balloon catheter. The cardiologist 
usually pre-bends the distal tip of the guidewire before insertion and 
then rotates (or torques) the wire once it has reached a branch artery to 
enable the guidewire to enter the branch. If the angle of the bend has to 
be adjusted, the guidewire must be removed, re-bent and reinserted, 
sometimes several times. Particular difficulty is encountered with 
prebending where an artery branches at one angle, and then sub-branches at 
a different angle. This procedure is attended by the risk of significant 
trauma to the arterial lining, and, in many cases, the obstruction cannot 
be reached at all with the guidewire and catheter. 
Coronary arteries are tortuous, have many sub-branches and often the 
obstruction is either located where the diameter of the artery is small 
or, by its very presence, the obstruction leaves only a very small opening 
through which a guidewire and/or catheter can be passed. Consequently, the 
cardiologist often finds it very difficult to maneuver the guidewire or 
catheter, which are typically several feet long, from the proximal end. 
Steering the pre-bent guidewire is further complicated by the fact that 
branches project at all different radial angles, thus necessitating 
rotation of the guidewire to the appropriate degree to enter the desired 
arterial branch. However, rotation of the distal end of the wire typically 
lags behind rotation of the proximal, control end, so that precise 
rotational control is not possible. Also, friction in the arteries can 
cause the distal end to rotate in a jerky fashion which can traumatize the 
vascular intima. 
In another application, Transluminal Laser Catheter Angioplasty (laser 
angioplasty), the delivery of laser energy from an external source to an 
intraluminal site to remove plaque or thrombus obstructions in vessels is 
accomplished by providing a waveguide such as a fiber optic bundle within 
a catheter. The nature of laser angioplasty requires an even greater 
ability to precisely manipulate the catheter, to control and aim the laser 
light at the specific plaques or thrombi to be removed. 
A variety of attempts have been made in the past to provide catheters which 
are steerable from the proximal end to enable the catheter to be aimed or 
advanced through non-linear body cavities. For example, U.S. Pat. No. 
4,723,936 to Buchbinder, et al. discloses a balloon catheter, which is 
said to be steerable from the proximal end. The catheter is provided with 
a deflection wire going along the entire length of the catheter, which may 
be axially displaced to cause deflection at the distal end. However, the 
tip of the catheter can be bent in one direction only, and the entire 
catheter must be rotated or torqued to be guided. A further disadvantage 
of this device is the inability to effectively straighten the catheter 
once it has been bent. Any ability of the Buchbinder catheter depends upon 
the axial compression of the steering wire therein. In addition, the 
design requires a relatively large diameter deflection wire, which 
precludes extremely thin diameter catheters, such as those preferred for 
use for laser or balloon angioplasty applications. 
U.S. Pat. No. 3,470,876 to Barchilon discloses a catheter device having a 
central lumen extending therethrough, and four tensioning cords extending 
along an inner wall of the catheter. The '876 patent specifically recites 
that catheters may be produced in accordance with the Barchilon design 
having diameters of 0.125 to 2 inches, and are suited for applications 
such as within the duodenal bulb or ascending colon. These diameters are 
unsuited for use as a guidewire in coronary angioplasty, which typically 
requires diameters in the area of as small as from about 0.014 to 0.018 
inches. 
In the context of coronary angioplasty applications, the prior art 
generally suffers from disadvantages such as limited steerability and 
excessive external diameters. Limited catheter tip steerability results in 
greater time spent in the body and significantly elevated risk of trauma 
both to the vascular intima and to the patient in general. Multiple 
insertions of guidewires or catheters may lead to thrombosis, as a result 
of coagulation commencing along a guidewire surface. Additionally, precise 
directional control in laser angioplasty is of the utmost importance to 
assure accurate aiming of the laser beam to ablate the attendant plaque. 
However, the only prior art catheters having multi-directional 
steerability are typically greatly in excess of practical angioplasty 
catheter diameters. 
In addition to limited steerability, the prior art guidewires, such as 
those disclosed by Buchbinder and in U.S. Pat. No. 4,719,924 to 
Crittenden, rely upon the spring tension of the guidewire coil (and the 
resilience of the distal end of the deflection wire, in the case of 
Buchbinder) to return the guidewire to the straight, unbent position. 
However, as important as deflecting the wire to enter a branch artery is 
straightening the wire after the branch is negotiated. Any ability to 
straighten in the prior art devices described above results from the 
spring tension or other structure in the distal end of the wire, which 
structures also compromise the desired floppiness of the guidewire tip. 
Thus, there remains a need for a small diameter steering device, which may 
be readily adapted for use in the construction of either guidewires or 
catheters, and which is especially suited for procedures such as balloon 
or laser angioplasty. Preferably, the steering device is constructed in a 
manner which permits a diameter as small as that of existing dilatation 
catheters or guidewires used in angioplasty applications, yet is capable 
of complete deflective movement, throughout a full 360.degree. range of 
motion, without axial rotation. 
SUMMARY OF THE INVENTION 
In accordance with one aspect of the present invention, there is provided 
an improved steerable guidewire or catheter implement of the type useful 
for percutaneous transluminal insertion into the coronary vascular system. 
The invention permits controlled negotiation of branches and turns to 
guide an angioplasty catheter or guidewire to an arterial stenosis or 
lesion or other treatment site without the need for prebending or torquing 
of the instrument. The distal tip on steerable implements made in 
accordance with one embodiment of the present invention can be 
controllably radially displaced in any direction, thus permitting a full 
360.degree. range of motion without the need to rotate the body of the 
steerable implement. 
In one embodiment of the present invention, a guidewire is provided having 
an elongate flexible shaft with a central lumen extending therethrough and 
a floppy resilient tip on the distal end. An axially extending steering 
post is disposed within a steering region on the distal portion of the 
flexible shaft. The steering post is pivotably secured at its proximal end 
to a radial support axially secured within the flexible shaft at the 
proximal end of the steering region, to prevent axial displacement of the 
steering post while at the same time permitting lateral deflection of the 
steering post out of parallel with the axis of the flexible shaft. 
At least one and preferably two or three or four deflection wires are 
axially movably disposed within the lumen of the flexible shaft, and 
extend proximally from a distal point of attachment on the steering post 
throughout the length of the flexible shaft to a control at the proximal 
end thereof. Each deflection wire passes through a notch or orifice on the 
radial support. 
In another embodiment, the steering post is provided with a wire anchor 
region at its distal end and a wire guide region at its proximal end. 
Preferably, the cross-sectional area of the post at a point intermediate 
the anchor region and guide region is less than the cross-sectional area 
of the post at least one of the anchor region and guide region, and, more 
preferably, is less than the cross-sectional area of the post at both the 
guide region and anchor region. 
In a further embodiment, a deflection wire anchor is disposed in the 
steering region of the flexible shaft, spaced apart in a distal direction 
from a deflection wire guide. Preferably, opposing pairs of deflection 
wires are formed by providing a continuous length of wire which loops at 
its midpoint across the distal end of the anchor, both ends extending 
through the flexible shaft in a proximal direction. 
Axial movement of any one of the deflection wires in a proximal direction 
displaces the axis of the steering post in a unique lateral direction, and 
through combinations of proximal axial displacement of more than two 
deflection wires, the steering post is caused to deflect laterally and 
rotate throughout a full 360.degree. range of motion about the axis of the 
flexible shaft. In a two wire embodiment, the deflection wires are 
preferably disposed in parallel to and on opposite sides of the 
longitudinal axis of the device to permit bending the tip by pulling on 
one wire and straightening the tip by pulling on the other wire. 
The steerable medical device of the present invention can thus negotiate 
tortuous and branched arterial systems, without the need for withdrawal 
and multiple insertions to deflect the tip, or axial rotation of the 
catheter body. The steerable medical device can be readily manufactured in 
accordance with known techniques, and at a low per unit cost. 
These and other features and advantages of the present invention will 
become apparent from the detailed description of preferred embodiments 
which follows, when considered together with the attached drawings and 
claims.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
Referring to FIG. 1, there is disclosed an elongate flexible implement 10, 
having a tubular body 11 with a proximal end 12 and a distal end 14. The 
distal end 14 comprises a steering region 16, and the proximal end 12 is 
provided with a control 18 for steering the implement 10, which may be, 
for example, a steerable guidewire or catheter. Although the steering 
device of the present invention will generally be described herein as 
incorporated into an angioplasty guidewire, it is to be understood that 
one skilled in the art will be able to readily adapt the steering device 
to other medical and non-medical applications. 
The body 11 of steerable implement 10 may be any desired length from inches 
to many feet depending upon the intended application. In an embodiment 
useful as an angioplasty guidewire or catheter, the body 11 will typically 
be several feet long, and will preferably be about 135-180 cm, as is 
typical of existing angioplasty catheters and guidewires respectively. 
However, any suitable length may be used. 
The body 11 may be constructed in any of a variety of ways known in the 
art, such as by tightly winding a coil of metal wire, or extrusion of a 
relatively flexible biocompatible polymer such as polyethylene. Wound 
guidewires preferably comprise a high tensile strength wire of a 
resilient, non-corrosive metal such as stainless steel or platinum, and 
may have a circular cross-section with a diameter of from about 0.001 to 
0.020 in. The wire may alternatively have a rectangular cross-section of 
from about 0.001 to 0.020 inches by from about 0.001 to 0.040 inches, or 
other variations known in the art. Construction materials and techniques 
for manufacturing wire wound guidewires are well known in the art, and a 
typical 180 cm teflon coated 0.014 inch or 0.016 inch diameter 
non-steerable guidewire may be obtained from U.S. Catheter, Inc., a 
division of C.R. Bard, Inc., located in Billerica, Mass. U.S.A. 
The external diameter of wire wound guidewires will of course be a function 
of the intended application. The wire wound coronary angioplasty 
guidewires incorporating the steering device of the present invention are 
preferably wound to have an external diameter in the range of from about 
0.014 inches to about 0.018 inches. In steerable catheter applications, 
the diameter of the catheter can be varied to optimize the diameter of a 
central working channel as desired, while still maintaining a sufficiently 
small exterior diameter for the intended application. Steerable balloon 
angioplasty catheters incorporating the present invention will typically 
have an exterior diameter in the range of from about 0.020 inches to about 
0.041 inches or larger as permitted by location of the lesion. 
Preferably, the exterior surface of the wound coil type guidewire shaft 10 
is provided with an elastic, biocompatible coating or sheath to provide a 
smooth outer surface. Suitable coatings can be formed by dipping, spraying 
or wrapping and heat curing operations as are known in the art. 
Alternatively, heat shrinkable tubing can provide a suitable outer sheath. 
A coating material should be selected which will permit sufficient flexing 
of the body 11 without cracking, will minimize sliding friction of the 
implement 10 during insertion and removal, and is substantially chemically 
inert in the in vivo vascular environment. A variety of suitable materials 
are known, including, for example, polytetrafluoroethylene, urethane or 
polyethylene. 
The body 11 of flexible implement 10 typically terminates at its distal end 
14 in a closed tip 20. Numerous guidewire and catheter tip constructions 
are known in the art and need not be detailed extensively herein. In 
general, the tip 20 is preferably a rounded closure constructed of a 
resilient polymeric material such as silicone or urethane which will 
minimize trauma to the vascular intima, as will be appreciated by one of 
skill in the art. As a safety feature, to facilitate complete removal of 
fragments of a broken guidewire, a safety wire may be secured at one end 
to the inside of the tip 20, and at the other end to the post 22 or 
support 24. 
Disposed intermediate the tip 20 and body 11 of a flexible implement 10 in 
accordance with the present invention is a floppy but controllable 
steering region 16. Steering region 16 is constructed in a manner that 
facilitates lateral displacement of the tip 20 relative to the axis of the 
body 11, through physical design and/or choice of flexible construction 
materials. 
For example, in a typical angioplasty guidewire or catheter, where the 
flexible body 11 comprises a metal wire coil, the revolutions of wire per 
unit of axial distance along the body is reduced in the steering region 16 
relative to body 11 to provide a looser wound coil having space 17 between 
adjacent wire loops, as illustrated in FIGS. 1-6. Thus, referring to FIG. 
2, it can be seen that lateral deflection of steering region 16 to the 
left may involve both an axial compression of adjacent wire loops on the 
inside surface 36 of the bend, and an axial separation of the adjacent 
wire loops on the outside surface 38 of the bend. 
Alternative designs or materials can be employed, provided that the 
catheter exhibits sufficient lateral flexibility. In general, the steering 
region 16 may be made from a variety of suitable metal or plastic coils or 
flexible sleeves. Materials opaque to X-rays, such as platinum, gold, 
tungsten, tantalum or the like, may be advantageously incorporated 
therein, to act as a fluoroscopic marker to aid in visualization. 
In accordance with the steering mechanism of the present invention, a 
steering post 22 is provided, extending in a generally axial direction 
within the steering region 16 of flexible body 11. Preferably, the 
steering post 22 is disposed coaxially within the central lumen of 
steering region 16 when the steering region 16 and body 11 are linearly 
aligned, such as when at rest. See FIG. 1. As will be described, the 
steering post 22 is secured in the steering region 16 in a manner that 
substantially prevents axial displacement thereof yet permits lateral 
deflection of the axis of the steering post 22 away from the axis of body 
11. 
Post 22 preferably comprises a resilient shaft which may be molded or 
extruded from any of a variety of materials, such as nylon, and may have a 
cross-sectional dimension of from about 0.002 inches up to about 0.012 
inches for use in a typical steerable angioplasty guidewire embodiment. 
Alternatively, a variety of resilient or springy metals in the form of 
wire can also be used to form post 22, such as phosphor bronze or other 
resilient metal. In general, it is desirable to select a material which 
will permit some degree of bending and return to its original shape, and 
will resist axial compression under the forces typically applied in the 
intended use of the steerable implement 10. 
The length of steering post 22 will, of course, be dependant upon the 
length of the steering region 16. In a typical steerable guidewire for 
angioplasty applications, the entire steering region 16 will be on the 
order of from about 0.040 to about 1.0 inches and preferably from about 
0.120 to about 0.150 inches long, and the steering post 22 may be from 
one-quarter to two-thirds that length. Although steering post 22 may 
extend distally all the way to the distal tip 20 of the steerable 
implement 10, it is preferred to limit the length to the proximal one-half 
or one-third of the axial length of steering region 16 to minimize 
rigidity in the steering region 16 yet permit sufficient steerability 
thereof. 
For example, in a typical angioplasty guidewire the distal end 27 of 
steering post 22 will be spaced apart from the interior surface of tip 20 
by a distance of from about one-tenth to one-half an inch or more, thus 
permitting the steering region 16 of the catheter shaft to be as floppy as 
desired. However, in an embodiment where the distal portion of a fiber 
optics bundle or flexible tube for defining a working channel additionally 
functions as the steering post 22, the post 22 will extend all the way to 
the distal tip 20 and be exposed to the outside by way of an opening 
therethrough. See, for example, FIG. 4. 
In a particularly preferred embodiment, steering post 22 is further 
provided with a bead or enlarged region 26 to optimize transmission of 
lateral force from the steering post 22 to the wall of steering region 16. 
For this purpose, bead 26 is most effectively located at or near the 
distal end of steering post 22. Bead 26 may be formed by dipping or 
coating techniques, or may be a preformed member having an opening therein 
for sliding over the end of steering post 22. Alternatively, post 22 can 
be molded or milled to provide a bead 26 integrally formed thereon. Bead 
26 is preferably substantially circular in a cross-section perpendicular 
to the axis of post 22, and the external diameter of the bead 26 is only 
slightly less than the interior diameter of the steering region 16 so that 
maximum lateral motion of the steering post 22 is transmitted to the 
steering region 16, but bead 26 also remains only in slidable contact with 
the interior surface thereof. 
The proximal end 23 of the steering post 22 is mounted to or in pivotable 
contact with a radial support 24, in a manner which permits pivoting of 
the steering post 22 throughout a full 360.degree. range of motion about 
the axis of body 11. The post may also be molded or milled as an integral 
part of disk 24. The support 24 comprises any means by which the 
deflection wires 28 are displaced radially outwardly from the axis of the 
tubular body 11, such as by the thickness of the post 22 or other 
structure including the plate embodiment illustrated in FIGS. 1-3. 
Referring to FIG. 1, the support 24 of the illustrated embodiment comprises 
a circular disk 25 located within the tubular body 11 of the steerable 
implement 10, preferably located near the distal end thereof. The disk 25 
is axially secured within the tubular body 11 to provide a stationary 
radial support for at least one deflection wire 28, and pivotable mount 
for steering post 22. Disk 25 may be attached, for example, by friction 
fit between adjacent turns of coiled spring wire. Steering post 22 
preferably is attached to or in contact with the disk 25 in a manner which 
permits it to swivel from 90 degrees to close to 0 degrees, relative to 
the lateral plane of disk 25. 
The disk 25 may be made of stainless steel or any of a variety of other 
suitable materials such as other metals or plastic polymers which will 
provide a sufficiently axially rigid seat for the proximal end 23 of 
steering post 22. Disk 25 may be formed by stamping from sheet stock and 
drilling, injection molding, or other techniques well known in the art. 
Preferably, a central depression or orifice is provided thereon, for 
providing an axial seat for steering post 22. The diameter of disk 25 can 
vary, however, it will typically be no greater than, but may approximate 
the outside diameter of the steerable implement 10. Diameters from about 
0.14 to 0.050 inches may preferably be used in the construction of cardiac 
angioplasty catheters. 
Lateral deflection of the steering post 22 away from the axis of body 11 is 
accomplished by proximal axial displacement of any of a plurality of 
deflection wires 28 extending proximally throughout the length of flexible 
body 11. Although only a single deflection wire 28 or two deflection wires 
can be used, preferably three or four deflection wires 28 are employed to 
provide a full 360.degree. range of motion of the steering region 16 about 
the axis of the body 11, as will become apparent. Only a single deflection 
wire 28 will be described in detail herein. 
The distal end of deflection wire 28 is secured such as by adhesives (or 
brazing or soldering, etc.) to the steering post 22 at the distal end 
thereof, or at a variety of other locations along the length of post 22. 
By "attached" or "secured" to the post and similar language herein, it is 
to be understood that the deflection wire 28 must be mechanically linked 
to the post 22 but need not necessarily be directly secured thereto. For 
example, the deflection wire 28 could be secured to an annular flange or 
ring surrounding the post or other structure which may be convenient from 
a manufacturing standpoint to provide a sufficiently secure linkage to 
accomplish the intended steering function. Alternatively, an eye on the 
end of the deflection wire can surround the post 22 and rest against a 
stop formed by a milled shoulder or adhesive, or other means of attachment 
as will be apparent to one of skill in the art. 
In one embodiment, the deflection wire 28 preferably extends radially 
outwardly from the point of attachment to the steering post 22 to the 
support 24. For this purpose, the support 24 is preferably provided with a 
notch or orifice 40 for each deflection wire 28 to extend through, said 
orifice 40 spaced radially outwardly from the axis of the tubular body 11 
by a first distance. The distal end of each deflection wire 28 is secured 
to the steering post 22 at a point radially displaced from the axis of the 
steering post 22 by a second distance, and the first distance is 
preferably greater than the second distance to maximize the lateral 
component of force. The second distance preferably approaches zero; 
however, it will inherently include the radius of the steering post 22 
where the deflection wire 28 is secured intermediate the two ends thereof. 
In the most preferred embodiment of the present invention, four deflection 
wires 28 are provided, each passing through an orifice 40 in support 24 
spaced at angles of approximately 90.degree. apart from each other along 
the plane of the support 24. In a three deflection wire embodiment, as 
illustrated in FIG. 1, each orifice 40 is separated from each adjacent 
orifice by an angle of approximately 120.degree.. 
The deflection wires may be made of stainless steel, nylon or any other 
suitable material which provides sufficient tensile strength and 
flexibility. The diameter of the lines can range from 0.001 to 0.005 
inches or more, and suitability of particular sizes or materials can be 
readily determined by experimentation. 
A control device 18 for steering the catheter is shown schematically in 
FIGS. 1-3. The control device 18 is preferably provided at its center with 
a pivotable mount 32 to permit it to be tipped throughout a full 
360.degree. range of motion. In the illustrated embodiment, control 18 
comprises a circular plate 34 secured to proximal end 12 of flexible shaft 
10 by way of pivotable mount 32. Deflection wires 28 are spaced equally 
radially outwardly from the pivotable center of the control device and at 
equal angular distances around the plate 34. Deflecting plate 34 from a 
plane normal to the axis of shaft 10 transmits force via one or more 
deflection wires 28, a component of which is resolved into a lateral force 
to deflect the catheter tip toward or away from the longitudinal axis of 
catheter. Selective tipping of the deflection plate 34 results in rotation 
of the catheter tip to any desired orientation. 
A variety of alternative control devices can be envisioned for use with the 
steerable implement of the present invention. For example, a "joy stick" 
type device comprising a single lever which can be displaced to any 
position throughout a nearly hemispherical range of motion might be used. 
As a further alternative, a portion of the proximal end 12 of tubular body 
11 is enlarged to a cross-section of a half inch or larger to facilitate 
grip. The enlarged section is provided with a plurality of axially 
slidable switches, one corresponding to each deflection wire 28. 
Manipulation of the switches by the thumb or forefinger will obtain the 
desired deflection of steering region 16. As will be appreciated by one of 
skill in the art, any control device will preferably be provided with a 
stop to prevent bending of the post 22 or steering region 16 past its 
elastic limit. 
A variety of factors impact the amount of the lateral force component 
exerted on steering post 22 by axial, proximal displacement of any of 
deflection wires 28. For example, as orifice 40 is moved further in a 
radially outward direction, the lateral force component will increase. 
Lateral displacement of orifice 40, however, is constrained by the maximum 
diameter that the steerable implement can have for an intended 
application. 
Alternatively, shortening the axial distance from the support 24 to the 
point of attachment 42 of the deflection wire 28 to the steering post 22 
increases the angle between the axis of post 22 and deflection wire 28, 
thereby increasing the lateral component of force. For this reason, 
support 24 is typically within one or two inches, and preferably less than 
one inch, from the distal tip 20 of an angioplasty catheter or guidewire 
embodiment of the invention. 
A further alternative is illustrated in FIG. 5. In this embodiment, a 
fulcrum 44 is provided at a point intermediate the radial support 24 and 
point of attachment 42 for maintaining the deflection wire 28 concave in a 
radial inward direction. The fulcrum 44 may conveniently comprise a 
substantially radially symmetrical member such as a sphere or toroid, 
which can also function to limit proximal axial movement of steering post 
22 through a central opening in support 24. In this embodiment, the point 
of attachment of deflection wires 28 may be to the fulcrum 44 instead of 
directly to the steering post 22. 
In accordance with a further aspect of the present invention, there is 
provided a steerable medical implement for use in percutaneous 
transluminal laser angioplasty applications. Referring to FIG. 4, there is 
disclosed an elongate flexible implement 45 comprising at its distal end a 
floppy steering region 46. As described with previous embodiments, 
enhanced flexibility may be imparted to steering region 46 by providing 
spacing 47 between adjacent loops of wound wire 48. 
A radial support means 49 is disposed at the proximal end of steering 
region 46, which may comprise a circular plate 50 or other structure for 
displacing deflection wires 52 radially outwardly from the axis of 
implement 45. 
A waveguide such as a fiber optic bundle 54 extends the entire length of 
the implement 45, for directing laser light from a source (not 
illustrated) disposed at the proximal end of the implement 45, to a point 
of application within a coronary artery at the distal tip 56 of the 
implement 45. For this purpose, the optical pathway 54 extends throughout 
the length of steering region 46 and traverses tip 56 by way of an opening 
58 therein. 
Each of the deflection wires 52 is secured at its distal end to the fiber 
optic bundle 54 at a point intermediate radial support 49 and distal tip 
56. Preferably, as has been previously described, the point of attachment 
of deflection wires 52 to the fiber optic bundle 54 is less than half the 
distance and preferably is within one-third of the distance between the 
radial support 49 and distal tip 56, in order to optimize the lateral 
component of force. 
Thus, utilizing a control device as previously described, a laser 
angioplasty catheter incorporating the present invention permits the 
controlled direction of a beam of light transmitted through fiber bundle 
54 at any desired point within a full 360.degree. circle on a plane normal 
to the axis of the implement 45. 
As is well known in the fiber optics art, numerous functions can be 
accomplished through a waveguide such as fiber bundle 54. For example, 
substantially parallel but discrete bundles of fiber optics can be secured 
adjacent one another within the fiber bundle 54 to permit a plurality of 
discrete light transmitting channels. Alternatively, a plurality of 
concentric optical pathways can be provided as is well known in the art. 
A plurality of discrete optical pathways may advantageously be used to 
perform a variety of functions. For example, a first optical pathway might 
be utilized to permit visualization of the stenotic site or other surface 
to be treated. A separate optical pathway may be utilized to transmit 
light for illuminating the site. Yet a third optical pathway might be 
utilized to transmit the laser light. These and other aspects of the fiber 
optics and laser light source are well known to those skilled in the fiber 
optics art. 
A variety of additional functions may be performed through use of the 
additional interior space within the housing of steerable implement 45. 
For example, in a preferred embodiment, an aspiration duct may be provided 
near the distal end of the implement 45, for suctioning debris or gases 
which may be generated as a result of the action of the laser. 
Alternatively, in place of a waveguide 54, a flexible tube may be 
incorporated into the steering device of the present invention, thereby 
providing a working channel to receive additional implements therethrough. 
Referring to FIG. 7, there is disclosed a further embodiment of the 
steering device in accordance with the present invention. The steerable 
device illustrated in FIG. 7 can be incorporated into a guidewire, or 
directly into a catheter, such as a balloon dilation catheter, or other 
elongate implement for which steerability is desired. It is to be 
understood that while certain preferred dimensions and construction 
materials will be recited in the discussion of the present embodiment, 
these illustrate a single angioplasty guidewire embodiment only and in no 
way limit the scope of the present invention. 
The steering device 60 preferably is incorporated into a steerable 
guidewire, of the type made from an elongate flexible tubular spring coil 
61 having a central lumen extending therethrough. The spring coil 61 may 
be further provided with an outer sheath or coating, as are known in the 
art, or the spring coil may, by itself, serve as the outer wall of the 
guidewire. As is well known in the art, the proximal end of the spring 
coil 61 is made up of a plurality of adjacent loops of wire. Lateral 
flexibility of the spring coil 61 at a distal steering region can be 
enhanced by providing a spacing between adjacent loops of the spring coil. 
These features are illustrated in FIGS. 1-6 of a previous embodiment of 
the present invention, and need no further discussion here. Alternatively, 
the adjacent loops of wire in the steering region can be in contact with 
one another, i.e., no axial spacing, when the steering region is in an 
orientation co-linear with the axis of the adjacent guidewire. 
Extending axially within the steering region of the spring coil 61 is a 
central post 62. Post 62 is preferably made from a flexible polymeric 
extrusion, although any of a wide variety of materials can be incorporated 
into the post 62 of the present invention. Most preferably, the post 62 
comprises a nylon rod having a substantially circular cross-sectional area 
and a diameter of about 0.004 inches. 
The distal end 64 of post 62 preferably is disposed at or near the distal 
end of the spring coil 61. For example, the distal end 64 in one 
embodiment terminates proximally of the guidewire tip (not illustrated), 
similarly to the embodiment illustrated in FIG. 1. Alternatively, the 
distal end 64 is in contact with the guidewire tip, which can be molded or 
machined integrally with the post 62 or secured thereto such as by known 
biocompatible adhesives. In either embodiment, the distal end of the 
spring coil 61 is provided with any of the known atraumatic tips 
conventional in the angioplasty arts, such as those formed by molding or 
dipping or brazing processes. 
Most preferably, the post 62 extends in a distal direction beyond the 
distal ends of wire guides 72 and for a predetermined length. Provision of 
such a length between the distal ends of the wire guides and effective 
point of attachment of the pullwires causes the steering region in 
operation to form an "elbow" bend, which is believed clinically desirable. 
In addition, the portion of post 62 disposed between the end of wire guide 
72 and the guidewire tip can function as a safety wire for securing the 
guidewire tip against in vivo detachment. 
By "elbow" bend, it is meant that the bend in the guidewire occurs at a 
relatively discrete position displaced proximally from the distal end of 
the guidewire. This enables a short length of floppy guidewire at the 
distal end to facilitate negotiation of the artery with minimal trauma to 
the vascular intima. 
The length of the floppy tip beyond the more rigid steering region of the 
guidewire can be varied, depending upon a number of considerations which 
will be apparent to one of skill in the art, including the diameter of the 
vessels expected to be traversed. In one specific construction of the 
embodiment of FIGS. 7 and 11, for example, the relative dimensions are as 
follows. Length of each of guide 68 and anchor 72: about 0.010 inches. 
Axial distance between guide 68 and anchor 72: about 0.006 inches. 
Distance between end of anchor 72 and distal tip of guidewire: about 0.140 
inches. Diameter of control post 62: about 0.004 inches. Diameter of 
spring wire of guidewire body: about 0.002 inches. Outside diameter of 
assembled guidewire: about 0.014 inches. 
The post 62 extends in a proximal direction through the spring coil 61 as 
far as may be desired for a given application, as will be understood by 
one of skill in the art. For example, the central post 62 may extend 
proximally only as far as the proximal wire guide 68, or further in a 
proximal direction to impart greater rigidity to the spring coil 61 than 
would otherwise be present. 
The post 62 must at some point along its length be secured against axial 
movement in the proximal direction relative to the spring coil 61. From a 
manufacturing standpoint, it has been found convenient to secure the 
proximal wire guides 68 both to the post 62 and to the interior surface of 
spring coil 61 for this purpose as will be discussed. However, the post 62 
can also be secured to the coil 61 at other locations, such as at the 
proximal end of an axially elongated post 62. 
A plurality of proximal wire guides 68 are provided for guiding each of a 
plurality of deflection wires 70. Preferably, four proximal wire guides 68 
are provided, equally spaced about the periphery of the central post 62. 
As will be apparent to one of skill in the art, three wire guides 68 
spaced equidistant around the periphery of central post 62 will also allow 
complete 360.degree. steerability of the guidewire. However, the use of 
four deflection wires 70 is preferred. Similarly, the guidewire can be 
constructed having only two or even a single proximal wire guide 68, with 
a commensurate reduction in the range of motion over which the guidewire 
may be steered. 
A plurality of deflection wires 70 extend axially throughout the length of 
the spring coil 61, each through a unique proximal wire guide 68 to the 
distal end 64 of post 62. Preferably, the distal end 64 of post 62 is also 
provided with a plurality of distal wire guides 72, corresponding to each 
deflection wire 70. 
In accordance with the preferred embodiment of the present invention, four 
deflection wires 70 are utilized, each deflection wire 70 having a unique 
proximal wire guide 68 and distal wire guide 72. Each of the deflection 
wires 70 may be secured to the distal end of the post in any of a variety 
of manners, which will be apparent to one of skill in the art, such as by 
mechanical anchors, adhesives or thermal or chemical welding. 
Mechanical anchoring or welding of the distal end of deflection wire 70 may 
be difficult to accomplish while providing sufficient strength to allow 
repeated steering maneuvers of the steering device 60 without separation 
of the distal end of deflection wire 70 from the distal end 64 of post 62. 
Thus, although the preferred embodiment is effectively provided with four 
deflection wires 70, they are actually two continuous deflection wires 
which loop across the distal end 64 of the post 62. A first deflection 
wire 70 extends distally through distal wire guide 72, continuously around 
or over the distal end 64 of central post 62 and back proximally through 
the opposing wire guide 72 and continuing on towards the proximal end of 
the instrument. In this manner, all four ends of the two continuous wires 
terminate at the proximal end of the guidewire where they connect to a 
control device permitting selective axial reciprocating motion thereof. 
In accordance with one preferred embodiment of the present invention, 
proximal wire guide 68 is in the form of an elongate tubular body for 
receiving the corresponding deflection wire 70 therethrough. The tubular 
wire guide 68 preferably is comprised of a material which can be readily 
adhered to the central post 62, and preferably also can be adhered to the 
adjacent loops of spring coil 61. Polyamide tubing, such as that 
manufactured by Polymicro Technologies, Inc. in Phoenix, Ariz., having an 
axial length of approximately 0.010 inches and an inside diameter of 
slightly greater than 0.0015 inches, preferably about 0.002 inches, has 
been found particularly suitable for this purpose, and can be readily 
adhered to a nylon post 62 using a suitable epoxy adhesive, such as that 
marketed under the name Ecobond by Emmerson Cuming of Canton, Mass. The 
length of the tube is less important than the diameter, and the diameter 
must be sufficient that a deflection wire extending therethrough is 
capable of reciprocal motion with sufficiently low friction that steering 
may be accomplished. The wall thickness of the tube will directly affect 
the minimum diameter of the assembled steerable guidewire, and is thus 
preferably minimized. For the polyamide tube disclosed above, the wall 
thickness is preferably as low as about 0.0003 inches. As illustrated in 
FIG. 8, the proximal wire guide 68 is conveniently affixed to the spring 
coil 61 by applying an epoxy 69 thereto. 
Deflection wire 70 extends distally beyond the end of the proximal wire 
guide 68, and preferably through a distal wire guide 72. Deflection wire 
70 is a fine wire of a diameter sufficient to provide enough tensile 
strength to allow steering of the guidewire without breaking, but small 
enough to permit construction of guidewires suitable for angioplasty 
applications. Preferably, a stainless steel wire is used, and diameters as 
low as about 0.0015 inches have been found functionally sufficient. 
However, a variety of other metals or polymers may be used, and the 
minimum appropriate diameter for any given material can be readily 
determined by one of skill in the art. 
Distal wire guide 72 is in the preferred embodiment a similar construction 
to proximal wire guide 68. Thus, distal wire guides 72 are formed by a 
plurality of elongate tubular guides adhered to the central post 62 for 
receiving the corresponding deflection wire 70 therethrough. 
Alternatively, the distal wire guide 72 can simply be a groove over the 
distal end 64 of post 62, or a bore hole extending transversely through 
the center of central post 62. 
Assembly of the steering device of the present invention may be 
accomplished in a variety of ways which will be understood by one of skill 
in the art, with many of the assembly steps being performed under 
microscopic vision. The proximal wire guide 68 and distal wire guide 72, 
when used, are preferably secured to the central post 62 by applying an 
adhesive thereto such as by dabbing with a 0.0015 inch diameter wire as an 
applicator. A first deflection wire 70 is threaded in a distal direction 
through corresponding proximal wire guide 68, through distal wire guide 
72, then back in a proximal direction through the corresponding wire 
guides on the opposite side of post 62 and drawn through to the proximal 
end of the instrument. This assembly procedure is repeated for a second 
deflection wire. With the deflection wires 70 in place, the entire distal 
end 64 of post 62 is dipped in or dabbed with an epoxy or other 
biologically compatible material to form a cap 65 to secure each of the 
deflection wires 70 against axial movement relative to the control post 
62. See FIG. 11. 
The entire assembly of post 62 wire guides and deflection wires is 
thereafter inserted distal end first into the proximal end of a standard 
spring coil 61 and advanced until the proximal wire guide 68 is 
approximately axially adjacent the beginning of the distal flexible 
steering region on the spring coil 61. An epoxy or other biocompatible 
adhesive 69 is thereafter applied between the adjacent loops of spring 
coil 61 to secure the proximal wire guides 68 to the spring coil 61, 
thereby preventing axial movement of the post 62 relative to the spring 
coil 61. It has been found that polyamide tubing can be epoxied to the 
adjacent spring coil 61 using a 0.002 inch wire or other applicator tip 
under microscopic vision. However, care must be taken that the epoxy does 
not flow into contact with the deflection wire 70, in which case the 
deflection wire 70 would be unable to slide axially within the proximal 
wire guide 68. 
Referring to FIGS. 8-10, there is disclosed a further embodiment of the 
steering device in accordance with the present invention. The steering 
device 76 comprises a main body 77 having a proximal wire guide 80, a wire 
anchor 84 and a pivot region 86. Preferably, the wire guide 80, pivot 86 
and anchor 84 are integrally formed from a single extrusion or molded 
part. 
In accordance with a preferred embodiment of the invention, the main body 
77 has a maximum diameter of as small as about 0.009 inches or smaller, 
and is substantially circular in outer cross-sectional configuration, 
except for a plurality of axially extending channels 85 for receiving 
guidewires 88 therethrough. Each of the channels 85 preferably has a depth 
of approximately 0.002 inches, so that 0.0015-inch diameter stainless 
steel wire can slidably extend therethrough. Channels 85 can conveniently 
be formed in the extrusion process as axial recesses of the type 
illustrated in FIGS. 8-10, or by providing parallel sets of radially 
outwardly extending flanges which extend axially to create a channel 85 
therebetween. 
Pivot 86 may be formed in any of a variety of ways, which will be apparent 
to one of skill in the art, and which will depend upon the construction 
material utilized. For example, in the case of a thermoplastic polymeric 
extrusion, the pivot region 86 preferably comprises a radially inwardly 
extending annular depression, which may be formed by application of heat 
and pressure or by stretching following the extrusion process. 
Alternatively, the pivot region 86 can be provided by producing an annular 
recess through other operations such as by physically milling or cutting 
portions of the extrusion away, or, wire guide 80 and anchor 84 can be 
secured to a length of metal or polymeric wire, spaced axially apart to 
provide a flexible length of wire therebetween. 
Preferably, the steering device 76 is provided with a deflection wire 88 at 
each of the four 90.degree. positions around the periphery thereof. (See 
FIG. 9.) As has been previously discussed, this can be accomplished by 
providing four separate guidewires which are anchored at the distal end of 
the steering device 76. However, four deflection wires 88 are effectively 
provided by assembling the steering device 76 with two continuous 
deflection wires 88, which loop over the distal end of wire anchor 84 and 
extend back in a proximal direction as has been discussed. 
In assembling the embodiment of the steering device 76 illustrated in FIGS. 
8-10, the deflection wires 88 are preferably crossed over the distal end 
of an extruded main body 77, axially aligned with the free ends extending 
in the proximal direction. The distal end of the wire anchor 84 is 
thereafter dipped in or dabbed with an appropriate adhesive, such as an 
epoxy, to form a cap 90 for securing the deflection wires 88 to the wire 
anchor 84. 
A tubular sleeve 82, such as a length of heat-shrink tubing, is thereafter 
passed over the distal end of wire anchor 84 and advanced proximally into 
alignment with the proximal wire guide 80 in a manner which captures each 
wire 88 within the respective channel 85. Upon application of heat, the 
annular sleeve 82 reduces in diameter to snugly adhere to the proximal 
wire guide 80. It has been found that the use of channels 81, having a 
depth of approximately 0.002 inches, leaves a sufficient tolerance after 
heat shrinking of sleeve 82 so that stainless steel wires having a 
diameter of approximately 0.0015 inches can freely axially move 
therethrough. 
The steering assembly is thereafter inserted into a standard guidewire coil 
78, and advanced until the proximal wire guide 80 is approximately aligned 
with the distal end of the flexible steering region of the coil 78. The 
radial outside surface of the annular sleeve 82 may thereafter be secured 
to the adjacent coil loops of coil 78, such as by the application of an 
epoxy or other adhesive 79, as has previously been described. 
As will be apparent to one of skill in the art, axial movement of any given 
deflection wire 88 in a proximal direction will cause the wire 88 to slide 
through the channel 81 in proximal wire guide 80, and, because the wire 88 
is immovably secured to the wire anchor 84, pivot region 86 will flex to 
permit lateral displacement of wire anchor 84 in the direction of the wire 
88 which has been proximally displaced. In this manner, as has been 
described, the steering device 76 permits selective lateral displacement 
of the distal tip in any direction, and restoration of the position of the 
distal end of the steering device back into axial alignment with the axis 
of the adjacent portion of the guidewire or catheter. 
In a modified version (not illustrated) of the device illustrated in FIGS. 
8-10, the pivot region 86 is deleted so that the assembled device has an 
anchor region 84 and a wire guide 80 axially spaced apart and secured to 
the coils of guidewire body 78. Thus, no post appears in this embodiment. 
In this embodiment, the deflection wires extend distally from the wire 
guide 80 toward the anchor 84 as before, but instead of extending 
substantially parallel to the axis of the steering device 76 as 
illustrated in FIGS. 8 and 10, each deflection wire crosses the axis of 
the steering device to the opposite side thereof. Thus, for example, one 
deflection wire 70 extends through wire guide 80 at the 90.degree. 
position, then distally at an incline relative to the axis of the steering 
device to the 180.degree. position on the anchor 84. The wire 70 
thereafter in the preferred embodiment loops around the distal end of 
anchor 84 and extends proximally through the channel 85 at the 90.degree. 
position thereof. Wire 70 thereafter extends diagonally across the axis of 
the steering device, through the wire guide 80 at the 180.degree. 
position, and proximally to the steering control. 
As a further alternative, the distal ends of the deflection wires (which 
may be the midpoint of a long, doubled back wire as previously discussed) 
are brazed directly to the wire coils of the guidewire body. A brazed 
joint is most conveniently accomplished on the outside surface of the 
guidewire body, and the deflection wires preferably extend radially 
outwardly between adjacent loops on the guidewire body for this purpose. 
In the case of two deflection wires formed from a single length of wire 
looping around the steering region of the guidewire, the deflection wire 
is conveniently looped around the outside of the guidewire body to provide 
a site for brazing. When a brazed joint is used, the distal wire anchor 84 
can be deleted. 
Referring now to FIGS. 12 and 13, there is shown in FIG. 12 a partial 
sectional perspective view of a two-wire steering device 100 with the 
outer tubular casing removed. FIG. 13 shows a partial elevational 
perspective view of a another embodiment of a two-wire steering device 120 
according to the present invention. The tubular outer body 111 of the 
simplified steering devices 100, 120 can be similar to that of any of the 
various embodiments previously described. 
In the simplified steering devices 100, 120 shown, there is provided a 
flexible steering ribbon 110 disposed within the central lumen of the 
steering region 116 of the tubular outer body. As will be discussed, 
"flexible" can mean either a ribbon which can be physically bent or flexed 
in use, or a more rigid structure provided with a narrowing thereon to 
form a hinge. In this embodiment, rather than complete 360.degree. 
steerability, controlled steerability within a single plane is achieved. 
The improvement over the prior art is that the steering region of the 
device, once controllably bent, can be restraightened by applying a 
positive traction to one of the deflection wires. 
The steering ribbon 110 may be molded, milled or extruded of any of a 
variety of known flexible materials, such as spring steel, nylon or other 
plastic materials. Preferably, the material will permit sufficient lateral 
flexibility while also exhibiting sufficient axial compressive strength to 
optimize transfer of axial force into lateral deflection. In a preferred 
embodiment, ribbon 110 is constructed of nylon. 
The steering ribbon 110, as shown, is preferably of substantially 
rectangular cross-section. However, different cross-sections and 
dimensions may also prove suitable. Preferably, any cross section which 
promotes flexibility in a single plane may be provided. 
For example, flexibility in a single plane can be facilitated by an 
appropriate pinching or narrowing of the ribbon 110 such as that sometimes 
referred to as a "living hinge". See FIG. 13. This type of hinge may be 
formed in a ribbon 110 of any cross-sectional configuration, by molding, 
pinching, milling or stretching operations to form a narrowing having a 
greater propensity to bend than other portions of the ribbon 110. 
Preferably, the hinge is formed by pinching in a ribbon 110 having a 
rectangular cross section, however, any cross-sectional configuration may 
be used so long as flexibility in a single plane is encouraged and the 
ribbon 110 has sufficient rigidity and strength to withstand the forces 
applied in multiple flexings and straightenings needed in steering the 
body 111. 
At least one deflection wire 170 is secured with respect to the ribbon 110. 
In a preferred embodiment, there are two deflection wires 170, one on each 
of two opposing sides of the ribbon 110 with the distal most portions of 
the deflection wires (which may be the midpoint of a continuous, doubled 
back wire as previously discussed) secured with respect to the steering 
ribbon 110 such as by brazing directly to the steering ribbon. A brazed 
joint may be accomplished as previously described. 
Referring to FIG. 13, a hinge 175 is provided along the ribbon 110 which 
provides a predicted bending point along the ribbon 110 when the 
deflection wires 170 are displaced. In the embodiment shown by FIG. 12, 
the hinge is effectively provided by an axial space between a wire guide 
172 and anchor 168 which can be similar to those described in connection 
with the embodiment illustrated in FIG. 7. In a preferred embodiment there 
is one guide 172 and one anchor 168 on each side of the ribbon 110 for 
each of two deflection wires 170. The two guides 172 and anchors 168 are 
disposed opposite each other to provide the hinge 175 as the space 
therebetween. The guides 172 and anchors 168 function to secure the wires 
to the steering ribbon as described in connection with FIG. 7 for securing 
the wires 70 to the steering post. The length, diameter, positioning, 
construction and assembly of the guides 172 and anchors 168 will be 
readily understood by one of skill in the art by reference to the drawings 
and description above in connection with FIG. 7. 
In the embodiment shown in FIG. 13, the hinge 175 is provided by an 
indentation 176 within the ribbon 110. This form of hinge is known as a 
living hinge due to the tendency of the hinge to return to its original 
position. Other forms of living hinges may also be provided. For example, 
the hinge 175 can be produced by providing a cut out portion in the 
ribbon, or can be provided by any known method of providing a hinge. 
Alternatively, the inherent flexibility of the ribbon may be used without 
the provision of a hinge. See FIG. 12. 
In another embodiment of the simplified steering device 100, the steering 
ribbon 110 may be replaced with two or more substantially parallel 
ribbons. 
In use, the steering device 100 or 120 can be steered in either of two 
directly opposite steering directions by displacing one of the deflection 
wires 170. By axial displacement of either of the two deflection wires, a 
range of motion of the tip of the device is achieved within a circular arc 
within a plane lying on the longitudinal axis of the steering device 100, 
120. 
After the device is introduced into the vasculature or other branched 
system, and a branch or a turn is encountered, in order to enter the 
branch or turn, the device can be rotated (torqued) to align one of the 
two steering directions with the branch or turn to be entered. The device 
can be steered by axial displacement of one of the deflection wires. 
Advantageously, after the device has been steered toward one direction, 
the device can be easily straightened by displacing the deflection wire 
opposing the side toward which the device was steered. The device can then 
be further advanced through the vasculature. 
It must be pointed out that the devices of the present invention can 
readily be modified by one of skill in the art to allow lateral 
displacement in only a single direction instead of two opposing 
directions. For example, the groove in a living hinge type device can be 
provided on only a single side of the steering ribbon, or other means for 
stopping or resisting flexing in one direction can be employed as will be 
readily apparent to one of skill in the art. 
An advantage of the simplified steering devices 100, 120 of the present 
invention is that they can be operated in a manner similar to that 
employed on convention steering devices for coronary angioplasty and other 
medical procedures. Thus, one skilled in the art of the prior art 
procedures could learn to manipulate the steering device of the present 
invention with little or no additional training. 
Although this invention has been described in terms of certain preferred 
embodiments, other embodiments that are apparent to those of ordinary 
skill in the art are also within the scope of this invention. Accordingly, 
the scope of the invention is intended to be defined only by reference to 
the appended claims.