Guidewire extension system with tactile connection indication

A guidewire extension system including a guidewire and an extension wire is disclosed. The system includes female and male connector segments located on the proximal end of the guidewire or the distal end of the extension wire. The hollow female connector segment, in one embodiment, includes a radial lip which intersects with lateral slots. The male connector segment includes an external groove. When the male connector is inserted into the female connector segment, the slots are expanded and the lip snaps into the groove providing a tactile indication that connection is completed. No restriction or frictional fit is created. The guidewire and extension wire are freely rotatable with respect to each other and can be multiply connected and disconnected. Methods of catheter exchange with tactile indication of guidewire extension wire connection are disclosed.

FIELD OF THE INVENTION 
The present invention relates in general to the field of guidewires. 
Guidewires are used to position catheters in exploratory procedures, 
diagnosis, and treatment of various medical conditions. More particularly, 
this invention relates to a guidewire extension system for connecting or 
coupling a guidewire, primary or initial wire to an extension or secondary 
wire during a medical procedure. 
BACKGROUND OF THE INVENTION 
Guidewires are used in various medical procedures to position medical 
devices at desired locations within a patient's vascular system. 
Guidewires, which are steerable, are inserted and maneuvered through the 
patient's vasculature to a previously chosen location. Once in place, the 
guidewire provides the means to place a non-steerable device, such as an 
over the wire catheter, at the chosen body site. For example, a catheter 
is slid over the guidewire until the catheter, or some working portion 
thereof, is positioned within the vasculature at the desired location. 
Generally speaking, guidewires of a standard length are longer than the 
non-steerable devices with which they are used to permit independent 
movement of the device and the wire. 
Angioplasty is one interventional procedure where a guidewire is often 
used. In angioplasty a dilatation catheter having an inflatable balloon 
structure is used to compress occlusive or blockage material against the 
sides of a vessel, thereby permitting (ideally) circulation to be 
reestablished. In preparatory procedures, the site of a vascular 
restriction, occlusion or stenosis is identified. In the usual procedure, 
the guidewire is inserted into the patient's femoral artery and maneuvered 
or steered to the location of the restriction. Maneuvering of the 
guidewire is facilitated by a video X-ray device which allows the 
physician to observe the movement of the guidewire's distal tip. The 
guidewire distal tip generally comprises a radiopaque metal to enhance 
X-ray viewing. A dilatation catheter then is inserted over the guidewire 
so that its working segment is located adjacent the restriction. Generally 
this means that the catheter balloon is positioned adjacent the vascular 
restriction or blockage. 
During a simple angioplasty procedure, the dilatation catheter balloon is 
inflated to open the restriction, and then is removed along with the 
guidewire. However, complications sometimes arise which prevent the 
physician from completing this simple procedure. Occasionally the balloon 
catheter malfunctions. Sometimes a larger (or smaller) balloon is required 
further to dilate the vascular restriction, or another device or other 
type of catheter is needed to remove vascular material. For whatever the 
reason, the guidewire extension system of this invention is used when the 
catheter, or other such device, has to be removed and replaced with 
another device or catheter. 
In the usual procedure to exchange catheters, the guidewire is removed from 
the patient, leaving the catheter in the vascular system. An exchange wire 
is inserted through the catheter and the catheter removed, leaving the 
exchange wire in place. The new catheter is inserted over the exchange 
wire and the exchange wire removed and replaced with the guidewire. 
It is desirable to keep the guidewire in the patient's vasculature for 
various reasons. One reason is that the initial placement of the guidewire 
requires extensive, time consuming, manipulation. Removal and 
repositioning of the guidewire would be equally time consuming, possibly 
requiring a patient to be exposed to additional drugs, radiation, and, in 
general, infliction of additional trauma to the patient. It is also of 
importance that once the guidewire has been steered to a position across a 
lesion, that the crossed lesion position not be lost by removal of the 
guidewire. Guidewires removed from a crossed lesion may induce spontaneous 
vascular restriction or closure making repositioning of the guidewire 
difficult if not precluded. 
In those cases where catheter exchange is desired, the physician would 
simply prefer to remove the catheter over the guidewire, leaving the 
guidewire positioned in the patient. However, to permit catheter exchange, 
a guidewire over which a catheter is to be exchanged must be sufficiently 
long to allow the physician to grip a portion of the wire as the catheter 
is being withdrawn over the guidewire. This requires the guidewire to be 
long enough to provide an external portion longer than the catheter in 
addition to the guidewire portion remaining in the patient. 
Unfortunately, a guidewire of sufficient length to provide suitably long 
external and internal portions has inferior handling characteristics, 
thereby making more difficult the steering and maneuvering manipulations 
needed for guidewire placement. The added length also imposes itself on 
the usually cramped vascular suite thereby causing distractions from other 
support activities. It is for these reasons that guidewires are usually 
only slightly longer than balloon catheters, e.g. 20-50 centimeters 
longer, and that a much longer exchange wire is used only with exchange 
procedures. 
Illustrating the above, a dilatation catheter has a shaft length in the 
range of about 120 cm to about 150 cm, a suitable guidewire for such a 
catheter would have a length in the range of about 150 cm to about 180 cm 
and an exchange wire would have a length in the range of about 260 cm to 
about 300 cm. As can be imagined from the above, utilization of an 
exchange wire in an exchange wire procedure is complicated and time 
consuming. This invention simplifies catheter exchange and eliminates the 
need to use an exchange wire. 
A recent development involves coupling or connecting a second length of 
wire, sometimes called an extension wire or secondary wire, to the 
exposed, proximal end of a positioned guidewire. The secondary wire length 
should be sufficient to allow the catheter to be withdrawn while leaving 
the primary or lesion crossing guidewire in the patient. Various 
approaches have been suggested for effecting the attachment of an 
extension wire to a guidewire. 
In one approach, such as that described in U.S. Pat. No. 4,922,923 to 
Gambale et al., a guide wire and an extension are joined together by 
crimping. A special crimping tool is disclosed in the Gambale et al., '923 
patent. A drawback of this approach is that once the wires have been 
crimped, the connection therebetween is substantially permanent, and the 
extension wire cannot be detached from the guidewire except by severing 
it, e.g., by cutting. 
Instead of crimping the guidewire to the extension wire, attempts have been 
made to engage the extension wire to the guidewire frictionally. Such 
attempts are described, for example, in U.S. Pat. No. 5,113,872 to 
Jahrmarkt et al., and related U.S. Pat. No. 5,117,838 to Palmer et al. 
These two patents disclose a guidewire extension system in which the 
distal end of the extension wire comprises a small diameter tube in which 
there is disposed a small diameter, open pitch, flat wire coiled spring. 
The proximal end of the guidewire has a reduced diameter portion which is 
inserted into the tube assembly to complete the connection. The reduced 
diameter proximal end of the guidewire is slightly larger than the 
internal diameter of the coiled spring of the extension wire, thereby 
creating a frictional engagement when one is inserted into the other. 
Palmer et al. disclose the utilization of a swivel joint for minimizing 
twisting of the extension guidewire when connecting or disconnecting it 
from the extension wire. A device as described in these two patents would 
be very difficult to manufacture reliably and apparently requires an 
alignment tool to ease insertion. 
U.S. Pat. No. 4,875,489 to Messner et al., discloses an extendable 
guidewire in which concentric tubular segments are secured to one or the 
other of the sections to be connected. The inner tubular segment has a 
longitudinal slot therein which permits it to expand when a cooperating 
male portion is inserted therein. The outer tubular member of the 
connector assembly restricts the expansion of the inner tubular member as 
the male portion is inserted therein. 
U.S. Pat. No. 4,846,193 to Tremulis et al., disclose a guidewire having 
first and second telescopically extendable sections movable between 
axially extended and retracted positions. No disengagement of the 
guidewire and extension wire is disclosed. 
U.S. Pat. No. 4,966,136 to Kraus et al., discloses an internally threaded 
female connection member secured to the distal end of the extension wire. 
The internally threaded female connection member is disclosed to be freely 
rotatable with respect to the extension wire with securement thereto by 
means of a collar. The body of the extension wire has a distal enlargement 
which cooperates with the collar to permit it to be freely rotated. The 
female connection member of the extension wire cooperates with a threaded 
male portion located on the proximal end of the guidewire. The mechanism 
disclosed by Kraus et al., requires the difficult step of threading the 
segments into each other. Threading pieces having the diameters of a 
guidewire and an extension wire into each other can be difficult to 
accomplish, especially under operating room conditions. 
U.S. Pat No. 4,827,941 to Taylor et al. discloses a guidewire-extension 
system employing a tubular female connector portion on one wire and a 
cooperating male portion on the other. The connecting male portion has an 
effective diameter in one radial dimension which is slightly larger than 
the inner diameter of the tubular portion. In a preferred practice, the 
male end portion of the Taylor et al. guidewire has an undulating shape, 
which, when inserted into the tube creates an interference friction fit. 
U.S. Pat. No. 5,247,942 to Prather et al. discloses a guidewire with a 
swivel. The Prather et al. invention provides for permanent connection of 
a main part and an extension part. A swivel is included in the system to 
permit the permanently affixed parts to be rotated with respect to each 
other to enhance steerability of the main or guidewire segment. The 
Prather '942 structure has the same drawback as the Gambale '923 system 
discussed above. 
U.S. Pat. No. 5,246,009 to Adams discloses a complicated guidewire assembly 
utilizing an inner core wire and an outer tube. Torque transmission is an 
aspect of the Adams invention. 
U.S. Pat. No. 5,271,415 to Foerster et al. describes a guidewire extension 
system comprising a tubular outer body with guidewire and extension wire 
elements, e.g., helically wound wires, therein. The device of Foerster et 
al. has the same disadvantage as that of the Kraus et al. '136 patent, 
i.e., the interconnect step requires threading of the parts into each 
other. Moreover, the device described by Foerster et al., with brazed 
wires inside a tubular structure, may be difficult to manufacture. 
The guidewire extension systems discussed above all have one or more 
drawbacks. Some are difficult or tedious or intricate to engage and 
disengage. Others do not disengage at all. While frictional engagement 
overcomes the disadvantages of crimping, disengagement may occur too 
easily. Problems of discontinuity at the guidewire/extension wire 
connection e.g., kinking, have been experienced with some systems. 
Moreover, prior extendable wires for use in coronary angioplasty 
procedures have been found to be unsuitable in peripheral arteries because 
the connections are not sufficiently strong. Further, some connections 
have larger diameters than the rest of the guidewire system. This may 
cause snagging of, e.g., over the wire catheters. It also means that the 
catheter with which such connection system is used must have a larger 
internal diameter lumen than would be necessary were a smaller diameter 
coupler employed. 
Accordingly, a principal object of the present invention is to provide a 
guidewire extension system which is reliable, easy to use and easy to 
manufacture. 
Another object of the present invention is to provide a guidewire extension 
system which does not require that either the guidewire or extension wire 
be rotated when attaching one to the other. It is advantageous that the 
guidewire be held stationary because the guidewire is located within the 
patient's blood vessel where unnecessary movement can induce trauma. It is 
also advantageous to have the majority of the length of the extension wire 
held stationary (e.g., by retention within a carrier structure) during the 
connection process. Having the extension wire self-contained in a tubular 
carrier package allows medical personnel to concentrate upon engaging the 
two wires using the present extension system. An uncontained extension 
wire is awkward, and thus complicates the process of effecting a 
guidewire/extension wire union during a medical procedure. 
It is a further object of this invention to provide an easily attachable 
(and reattachable) and easily detachable guidewire extension system which 
has a readily identifiable tactile sensation, e.g., a "snap", when the 
system components are affirmatively attached. 
It is still a further object of the present invention to provide a 
guidewire extension system which has substantially the same flexibility 
and pushability at its connection as that of the remainder of the length 
of the guidewire. The system provides an advantageously controllable 
coaxial alignment of the guidewire and extension wire. 
It is yet another object of the present invention to provide a unitized 
guidewire extension system having a substantially uniform, smooth, 
continuous outer diameter or profile along the guidewire, connector, and 
extension wire. A smooth, continuous transition in external profile from 
the distal end of the guidewire to the proximal end of the extension wire, 
especially over the connector segment, permits an over-the-wire catheter 
to be positioned without becoming hung up. Methods of manufacturing an 
extension system of this invention and methods of using a system of this 
invention also are disclosed. 
BRIEF SUMMARY OF THE INVENTION 
Briefly, in one aspect, the present invention is an extension system for 
affirmatively connecting the proximal end of a guidewire to the distal end 
of an extension wire. In its connected form, the entire structure is 
sometimes referred to herein as an exchange wire. In one practice, a 
tactile "snap" is experienced by the user when guidewire/extension wire 
connection or docking is achieved. 
In accordance with one aspect of the present invention, there is provided a 
coupler for a guidewire/extension wire system, the coupler comprising a 
male segment and a cooperating female segment. The coupler of this 
invention permits multiple coupling and decoupling, as needed, of the 
guidewire/extension wire to which it is attached. The male and female 
segments are fixedly attached to one or the other of the distal end of the 
extension wire or the proximal end of the guidewire, and yet the system 
permits either or both of the guidewire/extension wires to be freely 
rotated with respect to each other without the structural complication of 
a separate swivel. 
The female coupler segment of this invention comprises a hollow, elongate 
sleeve, the sleeve having opposite ends and a sleeve wall which defines 
inside and outside sleeve diameters, one of said ends having an inside 
diameter such that it can be firmly attached to one of said guidewire or 
said extension wire, the other of said ends defining a lip, and a 
plurality of lateral slots, said slots intersecting said lip so that the 
lip can be separated by insertion of said male segment. In a preferred 
practice, the lip is circular or semi-circular and is defined by one end 
of the sleeve. 
The male coupler segment of this invention comprises an elongate member 
located on the other of the guidewire or extension wire. The elongate 
member has an exterior surface and opposite ends which are referred to 
herein, as insertion or leading and following or connection ends, 
respectively. The insertion or leading end of the elongate member is the 
first portion of the elongate member to enter the female sleeve in the 
coupling process. The male coupler segment is affixed to the proximal end 
of the guidewire or the distal end of the extension wire, as appropriate. 
Several attachment locations and methods of attachment are discussed 
below. The exterior surface of the elongate member defines at least a 
portion of a radial groove and an annular shoulder in the following end, 
the groove having a diameter which cooperates with the female coupler 
segment lip so that when said male member is inserted into said female 
segment, the lip passes or slides along the exterior surface of the member 
in a slightly separated position, passes over said shoulder and returns to 
a non-separated position within the groove or notch. In this manner, the 
female coupler segment is retained substantially coaxially along the male 
coupler segment after insertion. Coupling occurs with a tactile sensation 
that insertion is completed, e.g., with an identifiable "snap". 
The extent of coaxial alignment can be controlled by adjusting the length 
of the overlap between the male coupler segment and the female coupler 
segment. For example, if a relatively longer male coupler segment is used, 
i.e., an elongate member which is relatively longer between its leading 
end and its groove, then axial alignment of the connected ends of the 
guidewire/extension wire is more rigidly maintained. Conversely, if a 
shorter male member (up to and including a substantially spherical ball) 
and a corresponding sized female coupler segment are used, then the axial 
rigidity of the overlapped coupler segments will be relatively minimal. 
One of the advantages of this invention is that the male member and the 
female coupler are conveniently coupled and decoupled using insertion and 
withdrawal forces easily applied by medical personnel. They are not 
permanently affixed to each other and no restriction or frictional fit is 
created. Neither of the male nor the female coupler segments are threaded, 
thereby eliminating the need to create those threads. This also eliminates 
any need to thread relatively small components into each other during a 
coupling/decoupling sequence. In practicing this invention, no rotation of 
either part is required in order to achieve coupling and decoupling. 
One skilled in this art will appreciate that there are likely to be a 
number of structural equivalents to the "lip" and "groove" construction 
described above. All of such constructions are within the scope of the 
present invention. For example, instead of a lip on the female coupler 
segment, one or more dimples or protrusions (or a series or locus of 
dimples or protrusions) could be machined, stamped, or molded therein. In 
that embodiment, the male segment would have surfaces, detents, or dents 
which would cooperate with the dimples to provide a tactile sensation at 
coupling and to couple the segments. A slide-stop (such as that mentioned 
in U.S. Pat. No. 5,247,942) could be used if the cooperating surfaces of 
the slide and stop permitted the slide/stop to be decoupled using 
decoupling or withdrawal forces in the range discussed below. 
It will also be appreciated that a "lip", as that term is used herein, may 
be located within the coupler sleeve rather than at one end. In such an 
arrangement, an intermediate narrow region or lesser diameter segment 
would be stretched, expanded or moved further within the coupler sleeve to 
create the tactile sensation of connection as the male member passed 
therewithin. Lateral slots could be utilized and could pass through the 
intermediate narrow region to permit the male member to pass therethrough 
more easily. 
In a preferred practice of this invention, the female coupler sleeve has 
two lateral slots, the slots being generally oppositely disposed. 
In a further practice, the outside diameter of the male coupler segment, as 
defined by its exterior surface, is less than the inside diameter of the 
female coupler sleeve, leaving an annular space therebetween and 
precluding a possible restriction or frictional interaction between the 
cooperating segments. 
In yet a further preferred practice, the male member has a tapered 
insertion end, permitting easy insertion of said male member into the 
female coupler sleeve. 
A guidewire extension system of this invention can be used to connect an 
otherwise conventional extension wire to a steerable guidewire having a 
plurality of multifilar, oppositely wound coils. Of course the guidewire 
also may have only a single coil, depending upon application. For smaller 
diameter guidewire applications, e.g., 0.014 in. diameter coronary wires, 
a guidewire core having no coil at all may be used. 
In another practice, the female segment is disposed on the distal end of 
the extension wire and the male segment is disposed on the proximal end of 
the guidewire.

DETAILED DESCRIPTION OF THE INVENTION 
As is shown in FIG. 1, a guidewire extension system 10 embodying features 
of the present invention has a guidewire or main section 11 which is 
adapted to be inserted into a patient's vascular system and an extension 
wire or extension section 12 which can be connected and disconnected to 
the main section 11. Connection and disconnection of guidewire 11 and 
extension wire 12 facilitates catheter exchange without the need for 
removing the main guidewire section 11 from the patient's vascular system. 
In the embodiment shown, guidewire section 11 generally comprises an 
elongated shaft 13 having a distal end (not shown in FIG. 1) with a male 
coupler segment 15 located at its proximal end. (The details of a 
preferred guidewire structure are discussed below.) Shaft 13 optionally 
may be covered with a polymeric, e.g., polytetrafluoroethylene (PTFE), 
polyurethane, or other coating (not shown). Single filar coils, multifilar 
coils, radiopacity markers, or other commonly utilized guidewire 
structures, may be disposed on shaft 13. These structures have been 
omitted from this description of the invention for purposes of clarity. 
Extension section 12 has an elongated shaft 24 with a hollow female coupler 
segment 26 secured to its distal end. Female coupler segment 26 may be 
fixed to extension wire 24 using techniques well known in this art such as 
resistance welding, crimping, gluing, soldering, or brazing. Female 
coupler segment 26 may comprise, for example, a suitably modified section 
of hypotube brazed to the distal end of an extension wire. Female coupler 
segment 26 may also be machined from a segment of solid, cylindrical core 
workpiece. Powder metallurgy techniques also may be used to manufacture 
female coupler segment 26. 
Also shown in FIG. 1 are the plurality of longitudinal slots 25 and a 
circular lip 16. Slots 25 intersect and divide circular lip 16 producing 
opposite, semicircular tabs 17, 18 which can be radially separated (in the 
direction of arrows 19) as male and female segments 15 and 26 are mated. 
Slots 25 may be machined into coupler segment 26 using conventional 
grinding and cutting operations or they may be created by any of a number 
of other known processing techniques including electrical discharge 
machining. The portion of the shaft 24 proximal to the female member 26 
may be covered with, e.g., a polymeric, or other type of coating. 
Male connector segment 15 is elongate, having opposite leading or insertion 
and following ends 20, 21 respectively. In this embodiment, insertion end 
20 is tapered (at 22) to ease the connection process. The exterior surface 
of male connector segment 15 further defines a radial groove 23. 
FIG. 2 illustrates the detailed interaction between lip 16 and radial 
groove 23. FIG. 2 is a cross-sectional view of an embodiment of the 
invention 10, shown in FIG. 1, after the segments have been coupled or 
"snapped" together. In this embodiment, female coupler segment 26 
comprises a section of hypotube which has been brazed (at 40) to extension 
section wire 12. Other methods of securement, e.g., soldering, or gluing, 
may be employed. As is shown, the glue, solder, or braze zone itself can 
be employed to provide a smooth transition between the guidewire or 
extension wire to which the female coupler segment is attached and to the 
coupler segment itself. 
A circular lip 16 of this invention is described in greater detail as 
follows. Circular lip 16 has a slightly rounded or tapered leading or 
opening edge 42, a substantially uniform or single diameter intermediate 
portion 44 and an angled or rounded interior edge or shoulder 46 which 
merges (at 50) to the interior diameter 48 of the hypotube section 26. 
Angled interior edge 46 can be, for example, the byproduct of drilling to 
create interior diameter 48. Interior edge 46, in cooperation with the 
configuration of radial groove 23, determines at least the magnitude of 
the force needed to disengage male and female coupler segments 15 and 26. 
Other factors such as the material employed, its treatment prior to 
incorporation into the present coupler, and the precise interaction 
between the slots and tabs also affect the magnitude of withdrawal forces. 
The details of male coupler segment 15 also are shown in FIG. 2. Male 
coupler segment 15 (best seen in FIG. 1) is defined by the configuration 
of exterior surface 60 of the male segment of the connector system. As was 
discussed above, male segment 15 has an insertion end 20 and a following 
end 21. Insertion end 20, in this embodiment, is rounded or tapered (at 
22) to provide ease of insertion. The outside diameter 62 of the male 
segment 15 leads to and defines radial groove 23. Radial groove 23, in 
this embodiment, comprises an angled, radiussed, or perpendicular annular 
shoulder 23A, a neck 23B which has a uniform diameter, and a radial stop 
surface 23C. Radial stop surface 23C can be disposed substantially 
perpendicularly to the axis of the guidewire extension wire system, as is 
illustrated, or it may be filleted or shaped to provide a more rounded 
stop. As shown, interior edge 46 of female coupler segment 26 is angled so 
as to be complimentary with and to cooperate with annular shoulder 23A 
when lip 16 is lying within radial groove 23. Radial stop surface 23C 
normally controls the extent to which the male and female coupler segments 
can be engaged, provided the elongate member is short enough to fit 
completely within female coupler segment 26 and not abut against the 
extension wire main section. For purposes of orientation, longitudinal 
slot 25 is shown in phantom. 
Three significant observations should be made with respect to the 
embodiment of FIG. 2. First, the interior diameter 48 of female coupler 
segment 26 is larger than the outside diameter 62 of male coupler 15. This 
fact means that no restriction or frictional fit is needed for coupling to 
occur between the male and female segments. The absence of a restriction 
fit also permits male and female coupler segments 15, 26 (and therefore 
the guidewire or extension wire to which they are attached) to rotate 
freely with respect to each other. In other words, this embodiment of the 
invention obviates the need for a structure like the swivel of U.S. Pat. 
No. 5,117,838 (Palmer et al.) described above. 
The second important observation is that the structure shown in FIG. 2 
provides a definite tactile "snap" when the segments are coupled. A sound 
may also be heard, especially in the larger sized peripheral wires. 
Whether a sound is generated or not, the tactile sensation of coupler 
engagement is a significant indicator to the system user that coupling is 
complete. A small amount of play, as shown in the system illustrated, also 
permits the physician to move the coupler segments with respect to each 
other and thereby establish that proper engagement has occurred. 
Thirdly, this system permits multiple, affirmative engagement and 
disengagements of the male and female segments, i.e., multiple catheter 
exchanges, can be accomplished. This is yet a further advantage over the 
prior art coupler systems which require permanent connection of the 
segments. 
FIG. 3 is a sectional view of a portion of the female coupler segment 26 of 
the present invention. FIG. 3A is an end view of the female coupler 
segment shown in FIG. 3. In particular, female coupler segment 26 
comprises a hollow tubular body 30 having a substantially circular lip 16 
with longitudinal slots 25 therein. Lip 16 has outside and inside edges 
16', 16", respectively, with a radial surface 16'" therebetween. Lip 16 
can be formed by any of several techniques. However, in the embodiment 
shown, lip 16 was formed by coining a segment of hypotube. This technique 
of formation is to be contrasted with that of FIG. 2 where drilling, 
cutting, and grinding steps were employed. It is noted that coining lip 16 
tends to create a more rounded or radiussed intersection (at 33) between 
tubular body 30 and lip 16 than the same intersection (at 50) in FIG. 2. 
The configuration of the interior intersection between the lip 16 and 
tubular body 30 will, to some extent, determine connector withdrawal 
forces. 
Slots 25 and lip or tabs 16 define flaps 17 and 18 which move from a 
substantially parallel, axial, alignment to a slightly oblique alignment 
(with respect to the system axis) in the coupling process. In the 
connection step, radial surface 16'" slides along the exterior surface 60 
of the male segment, separating the semicircular flaps 17, 18 to a 
slightly opened position. Tubular body 30 biases flaps 17, 18 toward each 
other and tends to reduce the radial width of slot 25. When the connection 
is made, flaps 17, 18 return to substantially their original position, a 
"snap" is heard or felt (or both), and the coupling process is completed. 
When the coupling process is complete, interior edge 16" aligns in 
substantially parallel fashion with shoulder 23A on male connector segment 
15. 
FIG. 4 shows in section the details of one possible approach to attaching 
female coupler segment 26 to elongated shaft 24. As was discussed above, 
in a preferred embodiment, elongated shaft 24 is the distal end of an 
extension wire but may also be the proximal end of a guidewire or main 
wire. Hollow tubular body 30 is attached to shaft 24 at resistance weld or 
spot weld 32. As is noted above, other techniques for attachment may be 
used. In FIG. 4 the elongated shaft segment coupled to tubular body 30 is 
shown to be ramped or tapered at 34. Taper 34 leads to an extension wire 
segment 36 which has substantially the same outside diameter as that of 
hollow tubular body 30. Elongated shaft 24 has been ground to a smaller 
diameter than wire segment 36 to enhance flexibility. Taper 34 therefore 
provides a gentle transition between the extension wire body and tubular 
body 30 which is particularly desirable. Taper 34 permits a catheter to 
pass over hollow tubular body 30 (e.g., during a catheter exchange 
process) without becoming caught on the connector system structure. 
FIG. 5 illustrates one possible connection structure between a guidewire 
proximal end 14 and a male coupler segment 15. The particular guidewire 
structure employed is that of a core wire 70 having oppositely wound 
multifilar coils 72, 72' disposed therearound. Core wire 70 has a reduced 
diameter proximal segment 74 which connects to core wire main section 76 
through taper 78. Coils 72,72' and reduced diameter proximal segment 74 
are attached to male coupler segment 15 e.g., by brazing, at 80 and 82, 
respectively. Male coupler segment 15 is brazed to guidewire proximal end 
82 at bore 84 which is drilled or machined in the following end 21 of male 
coupler segment 15. It is important that there be a smooth transition from 
male coupler segment 15 to the remaining structure of the guidewire so 
that a catheter can slide smoothly thereover during an exchange process. 
FIG. 6 illustrates another embodiment of the invention wherein groove 23' 
comprises a shoulder 23A', a portion of reduced diameter segment 74 
indicated at 23B' and the proximal end of coils 72, 72' indicated at 23C'. 
There are many possible ways to construct a groove which will cooperate 
with a connecting female segment in accordance with this invention. 
FIGS. 7, 8, 9, and 11 illustrate variations in construction of a male 
connecting segment of this invention. The variations illustrated are 
alternative ways in which the desired external configuration of the male 
coupler segment can be created. In each of the systems illustrated, a 
reduced diameter proximal guidewire segment 90, 91, 92, 93, respectively, 
is attached (at 94, 95, 96, and 97, respectively), to elongate male 
connector segment 98, 99, 100, and 101 respectively. In each instance a 
groove 102, 103, 104, and 105 is created or defined. FIG. 7 illustrates a 
coined sleeve that is attached to the wire core 90 by application of glue, 
solder, or braze through opening 97 on the insertion end of the segment 
98. This procedure keeps annular shoulder 150 clean. FIG. 8 illustrates a 
plasma ball weld 95 utilized on the insertion end of male connector 
segment 99. 
FIGS. 8, 8A and 8B illustrate different sized guidewires in which the 
present invention has been used. For example, the guidewire shown in FIG. 
8 would be the structure of a 0.035 in. and 0.038 in. diameter guidewire 
having two counterwound spring coils 72, 72'. The embodiment of FIG. 8A 
has a single spring coil 72 and would be structure employed in a 0.025 in. 
diameter guidewire. 
FIG. 8B is a structure useable for very small diameter, e.g., 0.014 in., 
guidewires. No spring coils are used. The extreme proximal end of the 
guidewire is ground to a lesser diameter and groove 103" is defined by 
elongate male connector segment 99, a reduced diameter segment 152, and 
taper 154. 
FIG. 9 shows a sleeve which was crimped (at 96) on the guidewire body core 
92. 
FIG. 11 illustrates an embodiment where the requisite external 
configuration of the male segment is externally formed into a segment of 
hypotube 160. Hypotube 160 then is brazed onto the proximal end of the 
guidewire and a rounded tip 120 is created on the remaining end. 
FIG. 10 illustrates an embodiment of the invention wherein the male 
connector segment external configuration 15 is simply machined into the 
proximal section of the guidewire, e.g., by centerless grinding. A radial 
groove or notch 110 defined by surfaces 112, 114, and 116 cooperates with 
the lip portion of the female coupler segment. 
FIG. 12 is a sectional view of an alternative embodiment of a female 
coupler segment 120 of this invention. In FIG. 12 a section of hypotube 
122 has a metal ring 124 brazed, soldered or glued (at 123) to its open 
end. Metal ring 124 has a diameter which is slightly less than the inside 
diameter of the hypotube 122 and thereby creates a lesser diameter lip 
126. As shown, this approach produces a substantially circular lip. 
Hypotube section 122 then is resistance welded, glued, soldered or brazed 
to the guidewire or extension wire core (at 128) with which it is 
associated. Electrical discharge machining or other known fabrication 
techniques then are used to create lateral slot 130. Alternatively, ring 
124 could be fitted inside of hypotube segment 122 to create an inwardly 
disposed "lip" as is discussed above. Regardless of the location of the 
lip, as long as the female and male segments overlap sufficiently, kinking 
at the connection will be reduced. 
The main guidewire section 11 is intended for use in positioning a catheter 
(not shown) in the vasculature of a patient, and it has a length 
corresponding to the length of a conventional guidewire for this purpose. 
Details of typical catheters and guidewires can be found in U.S. Pat. No. 
4,538,622 (Samson et al.) and U.S. Pat. No. 4,569,347 (Frisbie). Those 
patents are incorporated by reference herein in their entirety. 
Extension wire 12 is sufficiently long so that when the main guidewire 
section 11 and extension wire 12 are connected together, the guidewire 
system or exchange wire 10 has an overall length suitable for catheter 
exchange without removing the main guidewire 11 from the patient's 
vascular system. With a catheter having a length on the order of about 65 
cm to 175 cm, for example, guidewire 11 would have a length of about 100 
to about 200 cm, and extension wire 12 would have a length of about 100 to 
about 200 cm (or longer). 
Shafts 13 and 24 and female segment 26 can be fabricated from essentially 
any suitable material, such as stainless steel, Elgiloy, or the shape 
memory alloy referred to as Nitinol (55% Ni-Bal. Ti). Each should have an 
overall largest diameter which allows, e.g., a dilatation catheter, to 
pass freely thereover. Preferably, the two shafts 13 and 24 are provided 
with a smooth transition between them. Either or both of shafts 13, 24 can 
be provided with a coating of polymers or elastomers such as PEBAX 
polyamide, polyurethane, polytetrafluoroethylene (PTFE), or other such 
material well known to one skilled in this art. 
Typical dimensions of the main guidewire section include an outside 
diameter of the shaft 13 of about 0.009 to about 0.065 inch, an outside 
diameter of the male insertion segment about 0.006 inch to about 0.050 
inch and a length of about 0.025 to about 0.250 inch. The female connector 
segment has dimensions which generally cooperate with the male segment 
dimensions and a length of about 0.060 inches to about 0.500 inches and an 
outside diameter of about 0.009 in. to about 0.065 in. While this 
invention is particularly applicable to the larger diameter guidewire, 
e.g., 0.038 inches and 0.035 inches, smaller diameter applications, e.g., 
0.025 inches or less, down to 0.009 inch diameter wires, are also within 
its scope. Generally speaking, the ratio of male segment outside diameter 
to length and female segment inside diameter to length will fall in the 
range of 1:10 to about 1:1, but more likely will fall in the range of 1:5 
to about 3:5. Having a length which is larger than the respective diameter 
tends to keep the wires more axially aligned, thereby minimizing unwanted 
bending and kinking. 
Percutaneous transluminal angioplasty is a medical procedure in which the 
present invention can be used. In use, the main guidewire section 11 is 
percutaneously introduced into the vascular system of a patient with a 
dilatation catheter through the skin by means of an introducer (not 
shown). The distal tip of the guidewire is advanced beyond the distal tip 
of the dilatation catheter while the latter is held in place. The main 
guidewire section 11 is advanced into the selected vessel. The guidewire 
tip is preferably advanced through the lesion and beyond it, in order to 
permit the balloon portion of the dilatation catheter to be positioned 
within the lesion over a more supportive section of the guidewire. Once in 
position, the main guidewire section 11 is held in place and the 
dilatation catheter is advanced along it until the inflatable balloon 
thereof is within the lesion. Male connector segment 15 remains outside 
the patient's body and outside any adapter which may be connected to the 
proximal end of the dilatation catheter. If necessary, e.g., to retain a 
sufficient length of the main guidewire section 11 outside the catheter 
for the physician to grip, the guidewire and catheter may be advanced 
together substantially in unison. 
To exchange catheters, the main guidewire section 11 is extended by 
manually snapping the female tubular member 26 onto the male member 15. 
When the two guidewire sections are engaged, the dilatation catheter can 
then be withdrawn from the patient's body over the extended guidewire 
system. 
A new dilatation catheter may then be introduced over the extension section 
12 and advanced along the main guidewire section 11 within the patient's 
body until the balloon crosses the lesion. Once the proximal end of the 
new catheter has advanced beyond the connection between female member 26 
and male member 15, section 12 can be removed from section 11 by 
unsnapping the female member 26 by pulling the two sections apart. This 
can be accomplished without disturbing the position of the main section 11 
in the patient's body. 
The above description describes utilization of the present invention 
primarily in coronary angioplasty catheter exchange. It is to be 
understood that this invention has application in essentially any 
procedure where a catheter is utilized for diagnostic or interventional 
applications. 
This invention has a number of important features and advantages. The two 
sections of the guidewire can be connected together whenever a longer, 
exchange wire is needed, and they can be disconnected whenever the 
additional length is not required. The two sections of the guidewire may 
be connected and disconnected (and reconnected, if desired) by the 
physician by simply "snapping" and "unsnapping" the male segment into or 
out of the female segment. Subsequent to engagement, the segments can be 
freely rotated with respect to each other (e.g., to permit the guidewire 
to be steered) and can easily be disengaged. This can be done as needed, 
and no special tools are required whether to make the connection or to 
separate it. Thus, catheter exchange is greatly simplified. This also 
permits the same guidewire to be repositioned to second and multiple 
additional vascular sites which then may be treated with different 
catheters, making the present system very versatile. 
As noted in the previous paragraph, a guidewire extension system of this 
invention can be multiply engaged and disengaged. The present invention 
therefore permits two or more catheter exchanges, during a medical 
procedure, without a need to reposition or exchange the main or guidewire. 
Generally speaking, the ease of disengagement (i.e., the pounds of force 
needed to disengage an extension wire from a guide wire) has been found to 
be in the range of about 0.2 to about 5.0 lbs., preferably about 0.3 to 
about 3.0 lbs., and most preferably about 0.7 lbs. to about 2.0 lbs. 
Factors which affect withdrawal forces include the overall device diameter 
(withdrawal forces being higher for larger diameter devices), wall 
thickness of the tube, slot configurations, the materials of which the 
male and female coupler segments are made, and the relationship between 
the cooperating surfaces on the male and female coupler segments. The more 
abrupt or acute the relationship, the higher the withdrawal forces. With 
reference to FIG. 2, the more nearly perpendicularly (relative to the axis 
of the device) shoulder 23A engages surface 46, the more difficult 
withdrawal of male coupler segment from the female coupler segment. 
It is apparent from the foregoing that a new and improved extended 
guidewire system has been provided. While the present invention has been 
described herein with the male connecting element fixed to the distal end 
of the main guidewire, and the female member located on the distal end of 
the extension section, it is obvious that the female connector member and 
male connector member may be interchanged. Moreover, it will be apparent 
to those familiar with the art that other modifications and improvements 
can be made without departing from the scope of the invention as defined 
by the following claims.