Electrophysiology catheter with multifunction wire and method for making

An electrophysiology catheter (2) includes a handle (4) and a catheter shaft (6) having a flexible tip portion (22) with one or more electrodes (26, 28). A radial deflection wire (42) connects the tip portion to a first manipulator (10) at the handle to radially deflect the tip portion to a curved shape. A multifunction wire (60) extends from a second manipulator (11) at the handle to the tip portion. The second manipulator slides the multifunction wire longitudinally to position the distal end (64) of the multifunction wire along the multifunction lumen (38). The distal end of the multifunctional wire and the multifunction lumen are configured to provide interfering torquing surfaces (68, 70) so that when a third manipulator (12) rotates or torques the proximal end (62) of the multifunctional wire, the torquing force exerted between the interfering torquing surface causes lateral deflection of the radially curved tip portion. The catheter is constructed so that lateral deflection of the radially deflected tip portion is totally or at least substantially in-plane lateral deflection.

BACKGROUND OF THE INVENTION 
Electrophysiology catheters are designed for use in mapping and/or ablation 
of the heart. Electrophysiology catheters typically include a number of 
band electrodes mounted to the tip portion of the catheter shaft and a tip 
electrode at the distal end of the catheter shaft. To properly manipulate 
the electrodes against the target sites within a heart, the tip portion 
must be flexible and capable of being manipulated into a variety of 
shapes. U.S. Patent application Ser. No. 5,487,757, entitled "Multicurved 
Deflectable Catheter," the disclosure of which is incorporated by 
reference, discloses an electrophysiology catheter in which the tip 
portion can be deflected radially by pulling on a manipulator wire and 
also defected laterally by rotating a core wire which extends into the tip 
section. In addition to the manipulator and core wires, this patent 
discloses the use of an axially slidable stiffener wire, the distal end of 
which can be located at different positions along the tip portion to 
change the stiffness of the tip, and thus the general size of the curve in 
the tip. 
SUMMARY OF THE INVENTION 
The present invention is directed to an electrophysiology catheter which 
combines the function of a torquable core wire and a slideable stiffener 
wire into a single element. In addition, the invention provides for the 
construction of the electrophysiology catheter in a manner so that the 
lateral deflection can be substantially in-plane lateral deflection. 
The electrophysiology catheter includes a handle from which a catheter 
shaft extends. The catheter shaft has a flexible tip portion carrying one 
or more electrodes. A radial deflection element, typically a manipulator 
wire, connects the tip portion to a first manipulator mounted to the 
handle. Operating the first manipulator causes the tip portion to be 
deflected or curved radially. A multifunction wire extends from the handle 
to within the tip portion. The multifunction wire has a distal end which 
slides within a multifunction lumen formed in the tip portion. This 
effectively changes the stiffness of the tip portion so to change the 
general size of the curve in the tip. The multifunction wire is coupled to 
a second manipulator mounted to the handle. The second manipulator is 
constructed to allow the user to slide the multifunction wire 
longitudinally along the catheter shaft so to position the distal end of 
the multifunction wire at a chosen position along the multifunction lumen 
within the tip portion. The distal end of the multifunctional wire and the 
multifunction lumen are configured, that is keyed to one another, to 
provide interfering torquing surfaces. The user uses a third manipulator 
to rotate the proximal end of the multifunction wire about its 
longitudinal axis. This causes the distal end of the multifunction wire to 
exert a torquing force against the interfering torquing surface of the 
multifunction lumen, thus causing lateral deflection of the radially 
curved tip portion. 
Another aspect of the invention relates to the ability to maintain the 
lateral deflection as substantially in-plane lateral deflection. That is, 
after the tip portion has been deflected radially to its desired curved 
shape by the manipulator wire, rotating or torquing the multifunction wire 
preferably results in lateral deflection of the tip portion such that the 
longitudinal position of the distal end of the tip portion does not change 
substantially. In-plane lateral deflection can be achieved by one or both 
of the following. One way is to ensure that the radial curvature of the 
tip portion is not proximal of the engaged torque-transmitting, 
interfering torquing surfaces. Because the main portion of the catheter 
shaft is commonly torsionally stiff, and thus difficult to torque, it is 
often preferred to limit the longitudinal sliding movement of the 
multifunction wire so that at its most proximal position, the distal end 
of the multifunction wire is at least a chosen, minimum distance from the 
junction of the tip and main portions of the catheter shaft. A second way 
to achieve in-plane lateral deflection is to ensure that the catheter 
shaft adjacent to the junction of the tip and main portions of the 
catheter shaft is torsionally permissive; that is it has low torsional 
stiffness and is highly torquable or twistable. This can be achieved 
either by selecting the catheter shaft material at the junction to be 
highly torquable, by using a rotary joint at the junction, or by other 
means as well. Using one or both of these approaches, lateral deflection 
can therefore be totally, or at least substantially, in-plane lateral 
deflection. 
In the preferred embodiment the torque-transmitting distal end of the 
multifunction wire is sufficiently flexible so it can be bent or flexed 
radially by pulling or pushing on the manipulator wire; however the 
remainder of the multifunction wire is preferably stiff enough so not to 
be bent, to any substantial extent, by pulling or pushing on the 
manipulator wire. This effectively ensures that the radially-deflected 
part of the tip portion will not be proximal of the engaged 
torque-transmitting, interfering torquing surfaces. 
Another advantage arises from the fact that only two wires, instead of 
three wires as in the past, need to be used to obtain the three functions 
of radial deflection, lateral deflection and change of tip curvature. This 
permits a larger-diameter manipulator wire to be used because there is 
more room available for the manipulator wire. The larger diameter 
manipulator wire has greater columnar strength so to permit the 
radially-deflected tip portion to be returned to its original, straight 
shape by pushing on the manipulator wire. This is unlike smaller-diameter, 
less-stiff manipulator wires which may not have the columnar strength to 
completely re-straighten the tip portion when the manipulator wire is 
pushed distally from the handle. This aspect can also permit the tip 
portion to be deflected in opposite directions depending on whether the 
manipulator wire is pulled or pushed. 
Other features and advantages of the invention will appear from the 
following description from which the preferred embodiment has been set 
forth in detail in conjunction with the accompanying drawings.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
FIG. 1 illustrates an electrophysiology catheter 2 including a handle 4 
from which a catheter shaft 6 extends. Handle 4 includes a body 8 to which 
first, second and third manipulators 10, 11 and 12 are movably mounted. 
Handle 4 also includes an electrical connector 14. Catheter shaft 6 
includes a main portion 16, having a proximal end 18 extending from handle 
4 and a distal end 20. Catheter shaft 6 also includes a tip portion 22 
having a proximal end 24 affixed to and extending from distal end 20 of 
main portion 16 at a butt joint 25. Tip portion 22 has a number of band 
electrodes 26 and a tip electrode 28, the tip electrode 28 being at the 
distal end of tip portion 22. 
Referring now also to FIGS. 2-2D, main portion 16 of catheter shaft 6 is 
seen to comprise a reinforced shaft body 30 defining a main lumen 32. Body 
30 is preferably made of a polyetherimide inner liner, a stainless steel 
wire braid and a PEBAX.RTM. (polyamide polyether block copolymer) outer 
jacket. The PEBAX outer jacket has a Durometer hardness reading of about 
40D--75D, and preferably about 55D. Main portion 16 is stiffer than tip 
portion 22 and, if desired, can be made to be stiffer closer to proximal 
end 18 than distal end 20. Tip portion 14 includes a tip portion body 34 
having, in this embodiment, three axially extending lumens, specifically 
electrical wire lumen 36, multifunction wire lumen 38, and radial 
deflection wire lumen 40. Body 34 is preferably made of PEBAX and has a 
Durometer hardness reading of about 35D-55D, and more preferably about 
40D. A radial deflection wire 42, typically made of PTFE-coated stainless 
steel, extends from first manipulator 10 at its proximal end to an 
insulating connector 46 adjacent to tip electrode 28. Wire 42 has a 
diameter of about 0.015 inch along most of its length but preferably 
tapers to a smaller diameter, such as about 0.009 inch, at its distal end. 
Insulating connector 46 is preferably made of PEEK, or another hard 
insulating material, and is thermally or otherwise bonded to the distal 
end 48 of tip portion body 34. 
In the preferred embodiment the section of tip portion 22 carrying 
electrodes 26, 28 is preferably stiffer than the remainder of tip portion 
22 to create a straight section at the distal end; such section of tip 
portion 22 could be more stiff or less stiff than the remainder of the tip 
portion depending upon the particular characteristics desired. To provide 
this additional stiffness, a hypotube 50, made of stainless steel, is 
positioned over radial deflection wire 42 between insulating connector 46 
and the most proximal band electrode 26. 
Electrical wires 52 extend from electrical connector 14 of handle 4, 
through main lumen 32 in reinforced shaft body 30, through electrical wire 
lumen 36 in tip portion body 34 and terminate at the various electrodes 
26, 28. Thermocouple wires 54, like electrical wires 52, pass from 
electrical connector 14, through handle 4, along lumens 32, 36 and 
terminate to form a thermocouple 55 housed within a cavity 56 formed in 
tip electrode 28. Thermocouple 55 is surrounded by a thermally-conducting, 
electrically-insulating material, such as LOCTITE 498 cyanoacrylate 
thermal cycling adhesive. Wires 52 are preferably insulated nickel wires. 
A multifunction wire 60, shown in FIGS. 2 and 3, has a proximal end coupled 
to second manipulator 11 of handle 4 and a distal end 64. Distal end 64 is 
about 20-40 mm and preferably 30 mm long, and has an oblong 
cross-sectional shape as seen best in FIG. 2C. Distal end 64 has 
cross-sectional dimensions of about 0.002 to 0.005 inch, and preferably 
about 0.003 inch, by 0.030 to 0.050 inch, and preferably about 0.040 inch. 
The remainder 66 of multifunction wire 60 has a generally circular 
cross-sectional shape of about 0.015 to 0.025 inch, and preferably about 
0.020 inch, diameter. Both distal end 64 and remainder 66 are sized to 
pass through multifunction wire lumen 38 which also has an oblong 
cross-sectional shape, preferably about 0.020 inch by 0.050 inch. Wire 60 
can have different cross-sectional shapes and can be made of stainless 
steel, nickel titanium, plastic or other materials which provide 
sufficient flexibility and torsional stiffness. Wire 60 is preferably 
coated with PTFE or some other low-friction material. 
The longitudinal movement of second manipulator 11 causes the like 
longitudinal movement of multifunction wire 60 to move distal end 64 
between a more proximal position of FIG. 2 and a more distal position of 
FIG. 3. In the position of FIG. 2, tip portion 14 is not as stiff along 
its entire length as when in the position of FIG. 3. Thus pulling, or 
pushing, on radial deflection wire 42 by the manipulation of first 
manipulator 10 causes tip portion 22 to assume a larger radius curved 
shape as shown in FIG. 2 or a smaller radius curved shape as shown in FIG. 
3. In the preferred embodiment remainder 66 of multifunction wire 60 is 
sufficiently stiff so that substantially all radial deflection of tip 
portion 14 occurs distal of the junction 67 of distal end 64 and remainder 
66. 
Radially deflected tip portion 14 can be deflected laterally by rotating or 
torquing the proximal end of multifunction wire 60 through the rotation of 
third manipulator 12. The section of multifunction wire 60 which slides 
longitudinally through third manipulator 12 (due to the longitudinal 
movement of second manipulator 11) has an other-than-round cross-sectional 
shape, such as a dumbbell-shape, which fits within a generally 
complementary hole in the third manipulator. This arrangement permits the 
user to torque the proximal end of the multifunction wire by rotating 
third manipulator 12 about the handle axis. The lateral deflection of tip 
portion 14 occurs because of the respective shapes of multifunction wire 
lumen 38 and distal end 64 of multifunction wire 60. That is, lumen 38 and 
distal end 64 have torque-transmitting, interfering torquing surfaces 68, 
70 which engage on the rotation or torquing of multifunction wire 60. Tip 
portion body 34 is sufficiently twistable/torquable (as opposed to shaft 
body 30) so that the twisting or torquing of catheter shaft 6 occurs along 
the length of the tip portion proximal of distal end 64 of multifunction 
wire 60. This length is indicated by distances 72 and 74 in FIGS. 2 and 3, 
respectively. 
The circular cross-sectional shape of remainder 66 of multifunction wire 60 
is generally preferred because of its torsional stiffness. The oblong 
cross-sectional shape of distal end 64 can be changed to other shapes, 
such as cruciform, so long as distal end 64 and multifunction wire lumen 
38 have interfering torquing surfaces. While distal end 64 and lumen 38 
will typically have similar cross-sectional shapes, they need not. For 
example, distal end 64 could have an oblong cross-sectional shape while 
lumen 38 could have a cruciform cross-sectional shape sized to provide 
interfering torquing surfaces with distal end 64. Other shapes, including 
shapes with curved interfering torquing surfaces, which key to one another 
could also be used. While multifunction wire 60 can be a one-piece wire, 
it is preferably made by welding distal end 64 and remainder 66 at 
junction 67. 
So long as this twistable/torquable portion 72, 74 is substantially 
straight, lateral deflection of curved tip portion 22 will not change the 
shape of curved tip portion 22. As a result, such lateral deflection of 
tip portion 22 is said to be in-plane lateral deflection. In-plane lateral 
deflection is illustrated in FIG. 4 with the radial deflection indicated 
by arrow 76 and the in-plane lateral deflection, in which the shape of tip 
portion does not change, is indicated by arrow 78. This is in contrast 
with the out-of-plane lateral deflection of conventional torquable 
electrophysiology catheters in which the lateral deflection force is 
exerted near the distal end of the tip portion of the catheter. 
Out-of-plane lateral deflection of the prior art, shown in FIG. 5, 
typically results from when the shape of the tip portion 80 of a catheter 
82 is changed by the lateral deflection of the tip portion in a 
corkscrewing type of manner. That is, during out-of-plane lateral 
deflection, the distal end 84 of tip portion 80 moves laterally in a 
rotary direction and also axially in a distal direction. 
In the preferred embodiment the torsional stiffness of tip portion body 34 
is basically uniform along its entire length. However, if desired a part 
of tip portion 14 adjacent to proximal end 24 can be made to have a lower 
torsional stiffness than the remainder of tip portion 14. Doing so helps 
to ensure that any curved tip portion 14 proximal of junction 67 does not 
torque to any substantial extent but rather the entire, or at least 
substantially the entire, torsion of tip portion 14 occurs adjacent to 
butt joint 25. This also helps to ensure that the lateral deflection of 
tip portion 14 is substantially in-plane lateral deflection since the part 
of tip portion 14 adjacent to butt joint 25 preferably remains straight 
during use. Instead of using a low torsional stiffness part adjacent butt 
joint 25, the same effect can be achieved using a rotational coupling at 
butt joint 25. 
When constructing electrophysiology catheter 2 it is preferred that 
movement of multifunction wire 60 be limited so that the minimum distance 
72 between distal end 64 of multifunction wire 60 and proximal end 24 of 
tip portion 22 is at least about 0.400 to 0.800 inch, and preferably about 
0.600 inch. This limits the amount of torquing force required and helps to 
ensure that lateral deflection of tip portion 22 occurs without 
substantially changing the shape of the curved tip portion during lateral 
deflection of at least 90.degree. in each direction. Maintaining the shape 
of the radially deflected tip portion 22 ensures that the lateral 
deflection of tip portion 22 is substantially in-plane lateral deflection. 
As used in this application, substantially in-plane lateral deflection 
exists when any change 90 in the axial position of distal end 84 of tip 
portion 80, as measured parallel to axis 92, for 90.degree. of lateral 
deflection is less than about 10% of the initial deflection 94 of distal 
end 84. 
In use, catheter shaft 6 is translumenly positioned through a blood vessel 
within a patient so that flexible, deflectable tip portion 22 is within 
the heart. Second manipulator 11 is moved longitudinally to position 
distal end 64 of multifunction wire 60 at the appropriate position within 
multifunction wire lumen 38 according to the size of the radial curve 
desired. An axial force is then applied by the manipulation of first 
manipulator 10 pulling on or pushing radial deflection wire 42 to cause 
tip portion 22 to move into a radial curve. Third manipulator 12 is then 
manipulated to rotate the proximal end of multifunction wire 60 thus 
causing the engagement of surfaces 68, 70 and the lateral deflection of 
tip portion 22. These various manipulations are done to allow the 
physician to properly position electrodes 26, 28 at the appropriate target 
site. If desired, these steps can be done in different order or one or 
more steps may be omitted or deleted. Mapping, ablation, or other 
procedures can then be accomplished through electrical connector 14, 
electrical wires 52 and electrodes 26, 28. 
Modification and variation can be made to the disclosed embodiment without 
departing from the subject of the invention as defined in the following 
claims. For example, it may be possible to combine the functions of second 
and third manipulators 11, 12 into a single manipulator which provides the 
functions of both.