U.S. patent application number 10/452084 was filed with the patent office on 2003-10-16 for cryogenic catheter with deflectable tip.
Invention is credited to Hayfield, John Frederick, Kovalcheck, Steven W..
Application Number | 20030195605 10/452084 |
Document ID | / |
Family ID | 25466882 |
Filed Date | 2003-10-16 |
United States Patent
Application |
20030195605 |
Kind Code |
A1 |
Kovalcheck, Steven W. ; et
al. |
October 16, 2003 |
Cryogenic catheter with deflectable tip
Abstract
A flexible cryosurgical catheter having a deflectable segment
adjacent its distal end, a pull wire through said catheter
connected to the deflectable segment, and a deflection mechanism in
its handle for pulling on the pull wire to establish a desired
curvature in the deflectable segment.
Inventors: |
Kovalcheck, Steven W.; (San
Diego, CA) ; Hayfield, John Frederick; (San Diego,
CA) |
Correspondence
Address: |
Neil K. Nydegger
Nydegger & Associates
348 Olive Street
San Diego
CA
92103
US
|
Family ID: |
25466882 |
Appl. No.: |
10/452084 |
Filed: |
May 30, 2003 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10452084 |
May 30, 2003 |
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09935296 |
Aug 21, 2001 |
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6572610 |
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Current U.S.
Class: |
607/138 ;
606/21 |
Current CPC
Class: |
A61B 18/02 20130101;
A61B 2018/0262 20130101; A61B 2017/003 20130101; A61B 2018/0212
20130101 |
Class at
Publication: |
607/138 ;
606/21 |
International
Class: |
A61N 001/00; A61B
018/18 |
Claims
We claim:
1. A cryosurgical apparatus comprising: a cryosurgical
refrigeration unit; a control handle connected in fluid flow
communication with said refrigeration unit; a tubular catheter
connected in fluid flow communication with said control handle,
said control handle for imparting axial torque to rotate said
catheter; a heat transfer element; a tip deflection mechanism in
said control handle; a pull wire connecting said tip deflection
mechanism to said heat transfer element, said tip deflection
mechanism being adapted to impart tension to said pull wire; a
deflectable tubular segment having a proximal end attached to said
catheter and a distal end attached to said heat transfer element,
said deflectable segment including a spine element having a
plurality of stacked flat wires oriented to cause said tubular
segment to deflect in a pre-selected plane in response to a tension
in said pull wire; and a refrigerant supply conduit within said
catheter, said supply conduit being adapted to supply refrigerant
from said refrigeration unit to said heat transfer element.
2. An apparatus as recited in claim 1 further comprising a flexible
multi-lumen core tube having a distal end and a proximal end, said
core tube positioned within said deflectable segment and being more
flexible near said distal end of said core tube than near said
proximal end of said core tube.
3. An apparatus as recited in claim 2 wherein said core tube has a
plurality of longitudinal lumens configured to give said core tube
a mass moment of inertia lower in said pre-selected plane of
deflection than in a direction perpendicular to said pre-selected
plane of deflection.
4. An apparatus as recited in claim 1 further comprising a flexible
spring tube within said deflectable segment for deflection in said
pre-selected plane in response to a tension in said pull wire, said
spring tube having a distal end and a proximal end and being more
flexible near said distal end of said spring tube than near said
proximal end of said spring tube.
5. An apparatus as recited in claim 4 wherein said spring tube is
configured to cause said spring tube to flex more easily in a
direction within said pre-selected plane of deflection than in a
direction not within said pre-selected plane of deflection.
6. An apparatus as recited in claim 5 wherein said spring tube
defines an axis and comprises a flat spring tube wire having a
rectangular cross section with the smaller of said flat spring tube
wire's rectangular dimensions directed radially from said axis of
said spring tube, and with the greater of said flat spring tube
wire's rectangular dimensions directed substantially axially along
said spring tube.
7. An apparatus as recited in claim 6 wherein said spring tube has
a distal end and a proximal end and the pitch between coils of said
spring tube is greater near said distal end of said spring tube
than near said proximal end of said spring tube to cause said
spring tube to be more flexible near said distal end of said spring
tube than near said proximal end of said spring tube.
8. An apparatus as recited in claim 1 wherein said deflection
mechanism in said control handle comprises: an axle pivotably
mounted to said control handle; a lever arm within said control
handle, said lever arm being fixedly mounted to said axle, said
lever arm being attached to said pull wire; and an activation lever
mounted on said control handle, said activation lever being fixedly
mounted to said axle; wherein said activation lever is adapted to
rotate said axle, which in turn is adapted to rotate said lever arm
to pull on said pull wire to impart a proximally directed
displacement to said pull wire thereby establishing a curvature of
said deflectable segment.
9. An apparatus as recited in claim 1 further comprising an
adjustable braking mechanism on said deflection mechanism, said
braking mechanism being adapted to selectively restrain axial
displacement of said pull wire during deflection of said
deflectable segment of said catheter while maintaining a set
tension when said deflection mechanism is moved over the range of
motion.
10. An apparatus as recited in claim 1 further comprising a sensor
located near said distal end of said catheter, said sensor being
selected from the group of sensors consisting of a thermocouple and
an ECG sensor.
11. An apparatus as recited in claim 1 wherein said plurality of
flat wires is four flat wires.
12. An apparatus as recited in claim 1 wherein said plurality of
flat wires is arranged to make said deflectable segment more
flexible near said distal end of said deflectable segment than near
said proximal end of said deflectable segment.
13. A cryosurgical apparatus comprising: a cryosurgical
refrigeration unit; a control handle connected in fluid flow
communication with said refrigeration unit; a tubular catheter
connected in fluid flow communication with said control handle,
said control handle for imparting axial torque to rotate said
catheter; a heat transfer element; a tip deflection mechanism in
said control handle; a pull wire connecting said tip deflection
mechanism to said heat transfer element, said tip deflection
mechanism being adapted to impart tension to said pull wire; a
deflectable tubular segment having a proximal end attached to said
catheter and a distal end attached to said heat transfer element,
said deflectable segment including a spine element and a flexible
spring tube, said spine element having at least one flat wire
oriented to cause said tubular segment to deflect in a pre-selected
plane in response to a tension in said pull wire and said flexible
spring tube positioned for deflection in said pre-selected plane in
response to a tension in said pull wire; and a refrigerant supply
conduit within said catheter, said supply conduit being adapted to
supply refrigerant from said refrigeration unit to said heat
transfer element.
14. An apparatus as recited in claim 13 wherein said spring tube is
configured to cause said spring tube to flex more easily in a
direction within said pre-selected plane of deflection than in a
direction not within said pre-selected plane of deflection.
15. An apparatus as recited in claim 13 wherein said spring tube
defines an axis and comprises a flat spring tube wire having a
rectangular cross section with the smaller of said flat spring tube
wire's rectangular dimensions directed radially from said axis of
said spring tube, and with the greater of said flat spring tube
wire's rectangular dimensions directed substantially axially along
said spring tube.
16. An apparatus as recited in claim 13 wherein said spring tube
has a distal end and a proximal end, and the pitch between coils of
said spring tube is greater near said distal end of said spring
tube than near said proximal end of said spring tube to cause said
spring tube to be more flexible near said distal end of said spring
tube than near said proximal end of said spring tube.
17. An apparatus as recited in claim 13 wherein said spine element
comprises a plurality of stacked flat wires.
18. A method for performing cryosurgery comprising the steps of:
providing a cryosurgery system including a refrigeration unit, a
torque transmitting flexible tubular catheter, a heat transfer
element, a pull wire connected to said heat transfer element, a
deflectable tubular segment having a proximal end attached to said
catheter and a distal end attached to said heat transfer element,
said deflectable segment including a spine element having a
plurality of stacked flat wires oriented to cause said tubular
segment to deflect in a pre-selected plane in response to a tension
in said pull wire; inserting said heat transfer element into a
vascular system of a patient; advancing said heat transfer element
through the vascular system of the patient; tensioning said pull
wire to establish a pre-selected curvature of said deflectable
segment; and supplying fluid from said refrigeration unit to lower
the temperature of said heat transfer element.
19. A method as recited in claim 18 further comprising the step of:
applying torque via said catheter to orient said deflectable
tubular segment in a desired direction.
20. A method as recited in claim 18 wherein said plurality of flat
wires is arranged to make said deflectable segment more flexible
near said distal end of said deflectable segment than near said
proximal end of said deflectable segment.
Description
CROSS REFERENCE TO RELATED APPLICATION
[0001] This application is a continuation of application Ser. No.
09/935,296, filed Aug. 21, 2001, which is currently pending. The
contents of application Ser. No. 09/935,296 are incorporated herein
by reference.
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
[0002] Not Applicable
BACKGROUND OF THE INVENTION
[0003] 1. Field of the Invention
[0004] The present invention is in the field of cryosurgical
catheters.
[0005] 2. Background Art
[0006] In the treatment of various medical conditions, it is
sometimes beneficial to apply an extremely cold temperature at one
or more selected, isolated locations in or near a selected organ in
the patient's body. As an example, it can be beneficial in the
treatment of cardiac arrhythmia to apply cryosurgical temperatures
at selected locations in the patient's heart, to create localized
areas of necrotic tissue. Similarly, it can be beneficial to apply
extremely cold temperatures at selected locations in other organs,
or in a vascular system of the patient. The application of
extremely cold temperatures can be achieved by inserting a flexible
cryosurgical catheter through a vascular system to the desired
location. The flexible catheter can have a heat transfer element at
or near its distal end. The heat transfer element can be cooled to
a cryosurgical temperature and placed in contact with a selected
area of biological tissue.
[0007] It would be desirable to facilitate the application of cold
temperatures by devising an apparatus with the ability to flex the
tip of the cryosurgical catheter in a desired direction, to assist
in guiding the catheter through a tortuous path to the selected
location in or near a selected organ, or in a vascular system.
BRIEF SUMMARY OF THE INVENTION
[0008] According to certain embodiments of the invention, a
surgical device is provided for applying cold temperatures at
locations within the human body, via minimally invasive techniques.
More specifically, the device may comprise a deflectable catheter,
passable through the larger blood vessels and cavities of the
heart, having a distal tip which can be deflected by remotely
located means. The apparatus has conduits for the delivery and
removal of refrigerant fluids within the catheter, and conductors
for the monitoring of temperature and electrical impulse. A
proximally located handle has a mechanism for activating the
deflection of a distal catheter tip in a single plane. In certain
embodiments, a flexible multiple conduit tubular vessel attached to
the handle terminates in a dual channel quick connect plug for
interfacing the catheter with a cryogenic fluid supply unit.
[0009] The catheter may have a torque transmitting tubular member
extending from the handle to a distally located flexible tubular
segment which, in turn, terminates in a high thermal conductivity
tip. A deflection mechanism in the handle may manipulate the
curvature of the distal flexible tubular segment of the catheter,
and a braking or locking mechanism in the handle may be used to
maintain a set curvature of the tip, with the tip deflection being
in a predefined plane. A portion of the deflection mechanism in the
handle insures that the axial tension imposed to effect deflection
of the catheter tip is not transferred to the catheter shaft,
thereby preventing transmission of force to the shaft. A mechanism
is also incorporated into the handle to aid in the straightening of
the distal tip section of the catheter, once deflection is
released. A tensioning mechanism maintains a user adjustable,
relatively constant tip deflection force throughout the range of
motion.
[0010] Another feature that may be provided in the catheter is a
device for monitoring interior catheter pressure near the catheter
tip region. The conduits for refrigerant fluid delivery and
removal, and the conduit for pressure monitoring are separated from
the deflection mechanism in the handle, thereby relieving the need
to hermetically seal the handle.
[0011] The novel features of this invention, as well as the
invention itself, will be best understood from the attached
drawings, taken along with the following description, in which
similar reference characters refer to similar parts, and in
which:
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
[0012] FIG. 1 is a perspective view of the apparatus according to
an embodiment of the present invention;
[0013] FIG. 2 is a partial longitudinal section view of the
apparatus shown in FIG. 1;
[0014] FIG. 3 is an elevation view of the proximal end of the
apparatus shown in FIG. 2;
[0015] FIG. 4 is an elevation view of a portion of the apparatus
shown in FIG. 2;
[0016] FIG. 5 is a longitudinal section view of the portion of the
apparatus shown in FIG. 4;
[0017] FIGS. 6 and 7 are transverse section views of the apparatus
shown in FIG. 2;
[0018] FIG. 8 is an elevation view of the distal portion of the
apparatus shown in FIG. 1;
[0019] FIGS. 9 through 15 are transverse section views of the
apparatus shown in FIG. 8;
[0020] FIG. 16 is a longitudinal section view of the portion of the
apparatus shown in FIG. 8;
[0021] FIG. 17 is a longitudinal section view of the distal end of
the portion of the apparatus shown in FIG. 16;
[0022] FIG. 18 is a longitudinal section view of an intermediate
part of the portion of the apparatus shown in FIG. 16;
[0023] FIGS. 19 and 20 are longitudinal section views of an
alternate embodiment of the distal portion of the apparatus shown
in FIG. 1; and
[0024] FIG. 21 is a partially exploded view of the apparatus of
FIG. 1.
DETAILED DESCRIPTION OF THE INVENTION
[0025] As shown in FIG. 1, the apparatus 100 includes a flexible
catheter 16 attached to a handle 20, which is attached by a
flexible tube 25 to a cryogenic fluid unit (not shown). As seen in
FIGS. 16, 17, and 18, a spring wire 4 and a pull wire 5 are
incorporated into the catheter 16, to facilitate a controlled
deflection of the distal portion of the catheter 16.
[0026] As shown in FIGS. 8, 16, 17, and 18, the distal tip 1 of the
catheter 16 is a closed end hollow tube which can be machined,
formed, cast or molded from a highly conductive metal, preferably
copper. The copper can be gold plated to insure biocompatibility.
Proximal to the catheter tip 1, there can be a tip union 3 formed
from a weldable metal, preferably stainless steel. The tip union 3
and the catheter tip 1 can be attached and hermetically sealed
together by soldering or brazing. The tip union 3 can in turn be
attached to a particularly flexible segment at the distal end of
the catheter 16.
[0027] Within the chamber 2 of the catheter tip 1, a plurality of
electrical conductors 7a,7b,7c,7d can be attached, for the
transmission of electrical signals. The electrical conductors
7a,7b,7c,7d can be seen best in FIGS. 7 and 9 through 13. Two of
the attached conductors can form a thermocouple, preferably a T
type with one wire material being copper and the second being
thermocouple grade constantan. A third conductor, preferably formed
of nickel, can be attached to the interior of the catheter tip 1,
for monitoring of electro-physiological signals. The electrical
conductors can be coated with an insulating material, such as
polyimide. A capillary tube 6 can terminate, at a distal end, in
the chamber 2 of the catheter tip 1. The capillary tube 6
preferably has inner and outer diameters of 0.010 inches and 0.016
inches, respectively. The distal orifice of the capillary tube 6
can be located approximately 0.05 to 0.07 inches proximal to the
distal end of the catheter tip 1. The capillary tube 6 is the
distal extension of a high-pressure refrigerant fluid line 29 which
extends proximally through the catheter 16, the handle 20, and the
flexible tubular connection 25 to the cryogenic unit. The distal
portion of the capillary tube 6 and its distal orifice comprise a
Joule Thomson expansion element.
[0028] Welded to the interior surface of the tubular tip union 3
are two metal components, a spring wire component 4 and a pull wire
component 5, both preferably stainless steel, which are located
diametrically opposed to each other. The spring wire component 4 is
composed of multiple flat wires, each of which is essentially
rectangular in cross section, with each rectangular wire having one
cross-sectional dimension significantly greater than the
cross-sectional dimension perpendicular thereto. This spring wire
component 4 extends proximally from the tip union 3 through, and
just proximal to, the flexible segment of the catheter 16.
[0029] The flat wires are stacked and attached to each other in the
spring wire component 4 to essentially form a leaf spring. More
specifically, the spring wire component 4 consists of a base flat
wire with a length slightly longer than the length of the distal
flexible segment of the catheter 16. Near the proximal end of this
base flat wire are stacked additional flat wires of progressively
shorter lengths, with each having a proximal end terminating
preferably a short distance distal to the proximal end of the base
wire. In the preferred embodiment, there are at least three of
these additional flat wires, with at least some of these having
progressively shorter lengths than the base flat wire. All of the
stacked flat wires preferably have similar rectangular
cross-sectional dimensions.
[0030] The distal end of the base wire of the spring wire component
4 is firmly bonded or welded to the tip union 3 distal to the
flexible catheter segment, and the proximal end of the base wire is
firmly bonded or welded to a shaft union 15 proximal to the
flexible catheter segment. The essentially rectangular leaf spring
4 functions as a spine through the flexible segment of the catheter
16, with the smaller cross-sectional dimension of the spine 4
defining a direction in which deflection of the flexible segment of
the catheter 16 will occur. The spine 4 also resists deflection of
the flexible catheter segment in a direction perpendicular to the
defined direction of deflection.
[0031] The second metal component attached to the tip union 3 is a
pull or tendon wire component 5 which, when axially tensioned,
imposes a bending moment on the flexible segment of the catheter
16, with a resulting deflection in the direction defined by the
spine component 4. The tendon wire 5 extends proximally from the
tip union 3 to a deflection mechanism in the handle 20.
[0032] Located proximally from the catheter tip 1 is a multi-lumen
core tube 9, which extends proximally, from a point approximately
two catheter diameters proximal to the catheter tip 1, through the
flexible segment of the catheter 16. The core tube 9 can be
extruded from a polymer material having a balance between its
structural properties and its elastomeric properties. A preferred
material for the core tube extrusion 9 is Pebax. The core tube 9
may consist of a continuous segment, or several axially arranged
segments of Pebax. For a continuous core tube 9, the hardness and
the elastic modulus are constant throughout its length. For the
multiple segment embodiment, each segment of core tube 9 can have a
hardness and an elastic modulus less than the hardness and elastic
modulus of the adjacent segment, progressing proximally to
distally. This results in a core tube 9 which is softer and more
flexible near its distal end than near its proximal end.
[0033] As shown in FIG. 14, the core tube 9 has multiple lumens,
which can be geometrically shaped and positioned to give the
flexible segment of the catheter 16 a mass moment of inertia lower
in the defined direction of deflection than in the direction
perpendicular to the direction of deflection. The preferred
embodiment of the core tube 9 contains five lumens
10a,10b,10c,10d,10e. The core tube 9 has a central lumen 10d for
passage of the tendon wire 5, and a rectangular lumen 10e
positioned outwardly from the central lumen 10d. The rectangular
lumen 10e is for passage of the spine wire 4. Diametrically
opposite the rectangular lumen 10e, on the other side of the
central lumen 10d, is located a half-annular shaped lumen 10a,
through which the capillary tube 6 passes. This half-annular lumen
10a also provides a return path for low pressure refrigerant gas.
Two additional lumens 10b,10c located outwardly from the central
lumen 10d carry the aforementioned electrical conductors
7a,7b,7c,7d.
[0034] Located at the distal and proximal ends of the core tube 9
are two rigid multi-lumen coupler elements 8,11, preferably
fabricated from a metal such as stainless steel. As shown in FIGS.
17 and 18, each coupler 8,11 is a multi-lumen tubular structure
with an outer diameter equivalent in size to the outer diameter of
the core tube 9. The preferred embodiment of the coupler 8,11 is a
tubular structure with at least three lumens 12a,12b,12c, as shown
in FIG. 15. These are a center circular lumen 12c, an essentially
oval lumen 12b located outwardly from the center lumen 12c, and a
partial annular lumen 12a that essentially encircles about 3/4 of
the circumference of the center lumen 12c. In the catheter
assembly, the center lumen 12c of each coupler 8,11, through which
the tendon wire 5 passes, axially aligns with the center lumen 10d
of the core tube 9. The oval lumen 12b of each coupler 8,11,
through which the spine wire 4 passes, aligns axially with the
rectangular lumen 10e of the core tube 9.
[0035] The distal coupler 8 is encased in the tip union 3, and the
proximal coupler 11 is encased or captured in the shaft union 15,
which is also a stainless steel tube. In the preferred embodiment,
the shaft union 15 is thin-walled, preferably having a wall
thickness less than about 0.003 inch, and it has a length at least
five times longer than the proximal coupler 11. The proximal
coupler 11 is rigidly held within the shaft union 15 by mechanical
means, such as a swage or bezel, or by soldering means, brazing
means, welding means, or a combination of the cited means.
[0036] In another embodiment shown in FIGS. 19 and 20, instead of
the core tube 9, a tubular compression spring 62 extends proximally
through the flexible segment of the catheter 16. The tubular spring
62 is located proximally from the tip union 3 and firmly attached
thereto, by being bonded, welded, soldered, or brazed. The tubular
spring 62 is composed of a flat wire having a rectangular cross
section, with the smaller of the rectangular dimensions directed
radially from the center of the tubular shape, and with the greater
of the rectangular dimensions directed substantially axially along
the tubular shape. The pitch between coils of the tubular spring 62
is designed to enable bending of the tubular spring 62
perpendicular to the axis of the catheter 16. The pitch may be
fixed or variable. In the preferred embodiment, the proximal
portion of the tubular spring 62 has a smaller gap between coils
than the distal portion of the tubular spring 62, causing the
tubular spring 62 to be more flexible near its distal end. The
tubular spring embodiment also has a multi-lumen proximal coupler
11 and a shaft union 15.
[0037] Inserted into, and rigidly fixed to, the center lumen 12c of
the proximal coupler 11 is a sheath union 17. The sheath union 17
is a single lumen formed metal tube. In the preferred embodiment,
the sheath union 17 is firmly held to the proximal coupler 11 by
mechanical means, or by being soldered, brazed or welded to the
center lumen 12c of the proximal coupler 11. Inserted into, and
rigidly fixed to, the center lumen 12c of the distal coupler 8 is a
distal coupler union 19. The distal coupler union 19 is a single
lumen formed metal tube with a flared distal end. In the preferred
embodiment, the distal coupler union 19 is firmly held to the
distal coupler 8 by mechanical means, or by being soldered, brazed,
or welded to the center lumen 12c of the distal coupler 8.
[0038] The pull or tendon wire 5 passes from the tip union 3
through the distal coupler union 19, then through the center lumen
10d of the core tube 9 or through the spring tube 62, then into and
through the sheath union 17. The essentially rectangular spine 4
passes through the oval lumens 12b of the couplers 8,11 and into
the catheter shaft union 15. The spine 4 may be firmly attached to
the shaft union 15 by welding means. The sensor wires 7a,7b,7c,7d
passing through the core tube 9 or the spring tube 62 freely pass
unobstructed through the partial annular lumens 12a of the couplers
8,11. Also passing through the partial annular lumens 12a of the
couplers 8,11 is the capillary tube 6 on the distal end of the high
pressure fluid line 29. The portions of the lumens 12a,12b,12c of
the couplers 8,11 not taken up by wires and tubes make up the low
pressure refrigerant gas return.
[0039] A flexible jacket 14 covers all of the catheter elements
from the shaft union 15 to the tip union 3, encasing the core tube
9 or the spring tube 62, and all other internal elements. The
flexible jacket 14 is a tube extruded from an elastomeric polymer
with a hardness and modulus of elasticity less than or equal to the
material of the core tube 9. The jacket 14 has sufficient wall
thickness to maintain circularity without buckling, during the
bending of the jacket 14 around a one inch radius, through a 180
degree angle. In the preferred embodiment, the jacket 14 has a
length of about 5 centimeters, a diameter of about 0.130 inch and
wall thickness of about 0.020 inch. The flexible tubular jacket 14
can be firmly attached to the distal portion of the outer diameter
of the shaft union 15 and to the proximal portion of the outer
diameter of the tip union 3, by a combination of adhesive bonding
and thermal fusion. The jacket tube 14 can also be thermally fused
to the core tube 9 or the spring tube 62. In the embodiment using
the spring tube 62, the spring tube 62 can impart additional hoop
strength to the jacket tube 14, thereby preventing buckling during
bending. The adhesive bonding and thermal fusing of the jacket tube
14 to the tip union 3 and the shaft union 15 creates a hermetically
sealed cavity extending from the catheter tip 1 to the shaft union
15.
[0040] Two millimeters proximal to the catheter tip 1, a sensor
band 13, preferably formed from platinum, is swaged, fitted or
bonded around the flexible jacket tube 14. Conductively attached to
the platinum sensor band 13 is a nickel wire, which is passed
through the wall of the jacket tube 14, and either into and through
one of the conductor lumens 10b,10c of the core tube 9 or between
the inner diameter of the jacket tube 14 and the outer diameter of
the spring tube 62, passing proximally past the shaft union 15. The
sensor band 13 and the nickel wire comprise a means for sensing ECG
electrical impulses.
[0041] A tightly wound wire coil sheath 18 encases the pull or
tendon wire 5. The sheath 18 terminates on its distal end within
the proximal portion of the sheath union 17 and is attached
thereto. The sheath 18 extends proximally through the catheter 16
into the handle 20. The sheath 18 preferably has an outer diameter
of about 0.021 inch, and is fabricated of tightly wound 0.003 inch
diameter wire. During deflection of the tip, axial displacement and
tensile force are imposed upon the pull or tendon wire 5. The
sheath 18 prevents axial compression of the catheter body 16. While
preventing axial compression of the catheter body 16, the coils of
the sheath 18 pack together, and the sheath 18 behaves as an
incompressible body, thereby allowing efficient transmission of
tensile force and axial displacement to the flexible portion of the
catheter 16, which results in the deflection of the flexible
portion of the catheter 16.
[0042] Connected, bonded and thermally fused to the shaft union 15
and the flexible jacket tube 14 is the main catheter shaft 63. The
catheter shaft 63 is a tubular element with an outer diameter
comparable in size to the outer diameter of the flexible jacket 14,
and with an inner diameter comparable to the outer diameter of the
shaft union 15. The catheter shaft 63 is a composite structure
designed to transmit torque to the catheter tip 1 and the flexible
portion of the catheter 16 during manipulation of the catheter
16.
[0043] In one embodiment, the catheter shaft 63 includes a
relatively stiff thin walled inner tube of thermoplastic, such as
polyimide. A stainless steel wire braid is placed over the
polyimide tube, and a more flexible polymer covers the wire braid.
In this embodiment, the inner polyimide tube has a thickness of
about 0.0015 to about 0.002 inch, the braid is woven from 0.001
inch wire, and the outer layer is a flexible polymer such as Pebax.
The flexible outer layer thickness is significantly greater than
the inner polyimide tube, preferably about 0.010 to about 0.015
inch. The catheter shaft 63 terminates on its distal end at the
shaft union 15 and the flexible segment of the catheter 16. The
catheter shaft 63 extends proximally through the handle 20,
terminating proximal to the handle 20.
[0044] In another embodiment, the catheter shaft 63 is comprised of
a thermoplastic extrusion with an embedded stainless steel braid.
The hardness and elastic properties of the extrusion, and the pitch
and number of wires in the braid are chosen to give the desired
torque transfer properties to the catheter shaft 63, as is well
known in the art.
[0045] The sensor conductors 7a,7b,7c,7d, the sheath-encased pull
wire 5, and the capillary tube 6 exit the proximal coupler 11,
enter into and pass through the catheter shaft 63, and exit the
catheter shaft 63 within the interior of the handle 20. An
additional small diameter tube, the gauge tube 22, is contained
within the catheter shaft 63 for monitoring of the return fluid
pressure. The gauge tube 22 has a preferable outer diameter of
about 0.029 inches and inner diameter of about 0.024 inches. The
gauge tube 22 terminates on its distal end adjacent to the proximal
coupler 11 and extends proximally through the catheter shaft 63,
exiting the catheter shaft 63 within the interior of the handle
20.
[0046] As shown in FIG. 7, a sheath tube 34 is employed about the
sheath 18. The sheath tube 34 has a preferable inner diameter of
about 0.024 inch, thereby allowing free movement of the sheath 18
within the sheath tube 34. During catheter usage, the pressure at
the distal end of the sheath tube 34 is below atmospheric. The
sheath tube 34 terminates proximally within the interior of the
handle 20, where pressure is essentially atmospheric. The length
and dimensions of the sheath tube 34 are designed to provide a high
resistance to fluid movement between the interior of the catheter
16 and the interior of the handle 20. With the sheath 18 and the
tendon 5 passing through the sheath tube 34, the available space
for fluid movement between the sheath tube 34 and the sheath 18,
and between the sheath 18 and the tendon 5, is minimal. Utilization
of a sheath tube 34 thusly configured allows the sheath 18 and the
tendon 5 components of the deflection apparatus to exit the fluid
filled interior of the catheter 16 with no subsequent leakage of
fluid, thereby eliminating the need to hermetically seal the handle
20.
[0047] The high pressure capillary tube 6 extends from the catheter
tip 1 to a point about 10 inches proximal to the catheter tip 1,
where it transitions into a larger high pressure tube 29. The
transition site is hermetically sealed and can withstand pressures
in excess of 1000 psi, without compromise. The high pressure tube
29 then extends proximally through the catheter shaft 63 and exits
the catheter shaft 63 within the interior of the handle 20.
[0048] As shown in FIG. 2, the handle 20 incorporates a means for
securing the catheter shaft 63, the articulation mechanism, an
electrical connector or receptacle 31, and a pathway for the
catheter shaft 63, the high pressure tube 29, and the gauge tube 22
to pass through. As the catheter shaft 63 enters the handle 20, it
is firmly captured and bonded into the catheter support 33. The
catheter support 33 is a hollow tubular structure with features on
its proximal end that allow for securing to slots within the handle
20.
[0049] The catheter shaft 63 enters the handle 20 on the distal end
of the handle 20, passes through the handle 20, and exits the
handle 20 through an exit port on the proximal end of the handle
20. Four exit site holes are made in the wall of the catheter shaft
63 within the handle 20. The exit site holes are drilled or cut
preferably at an angle of about 10 to 15 degrees off the axis of
the catheter shaft 63, thereby allowing tubes within the catheter
shaft lumen to exit without deformation or buckling. One exit site
hole (not shown) is provided to allow the high pressure tube 29 to
exit the catheter shaft 63. Another exit site hole (not shown) is
provided to allow the gauge tube 22 to exit the catheter shaft 63.
A third exit site hole 46 is provided to allow the sensor wires
7a,7b,7c,7d to exit the catheter shaft 63. A fourth exit site hole
is provided to allow the sheath tube 34, the sheath 18 and the
tendon wire 5 to exit the catheter shaft 63.
[0050] In the preferred embodiment, the high pressure tube 29 exits
the catheter shaft 63 within the handle 20 at the most proximal
location, extends essentially parallel to the catheter shaft 63,
and exits the handle 20 through the exit port on the proximal end
of the handle 20. A hermetic seal is placed about the juncture
where the high pressure tube 29 exits the catheter shaft 63. Just
distal to the high pressure tube exit site hole, is the gauge tube
exit site hole. In the preferred embodiment, the gauge tube 22
exits the catheter shaft 63 within the handle 20, extends
essentially parallel to the catheter shaft 63, and exits the handle
20 through the exit port on the proximal end of the handle 20. A
hermetic seal is placed about the juncture where the gauge tube 22
exits the catheter shaft 63. At a site slightly distal to the gauge
tube exit site hole, the sensor wires 7a,7b,7c,7d exit the shaft
63, pass across the handle 20 and are conductively connected,
soldered, or crimped to an electrical receptacle 31. Hermetic seals
are placed about the connection of the wires to the receptacle 31
and about the wire exit site hole 46 on the shaft 63.
[0051] At a site just proximal to the point where the catheter
shaft 63 enters the handle 20, the sheath tube 34, the sheath 18
and the tendon wire 5 exit the catheter shaft 63. A hermetic seal
is place about the sheath tube 34 exiting the catheter shaft 63.
The tightly wound coil spring which makes up the sheath 18 exits
the sheath tube 34, is looped slightly, and then transitions into a
larger tightly wound coil spring, the sheath extension 35,36. The
loop 37 in the sheath 18 as it exits the catheter shaft 63 is a
service loop which allows the sheath 18 to move independently of
the catheter shaft 63, thereby preventing the imposition of tensile
or compressive forces on the catheter shaft 63.
[0052] The sheath extension 35,36 passes through, and is firmly
bonded, welded, soldered, or brazed to an adjustment screw 44 with
an attached adjustment nut 45. The adjustment screw 44 and nut 45
are securely positioned within the handle 20. Rotation of the
adjustment nut 45 on the screw 44 moves the screw 44 and the
attached sheath extension 35,36 distally or proximally, depending
on the direction of rotation of the nut 45. Use of the adjustment
screw 44 and nut 45 allows for fine adjustment of the service loop
37 of the sheath 18. The adjustment screw 44 also divides the
sheath extension 35,36 into a compressive segment 35 distal to the
screw 44, and a tensile segment 36 proximal to the screw 44. The
purpose of this division will become apparent later.
[0053] The sheath extension 35,36 and the enclosed tendon wire 5
exit the proximal side of the adjustment screw 44 and pass around a
pulley 38, to a point where they are both firmly connected,
preferably swaged or crimped, to a swivel connector 39. In this
connector 39, the proximal end of the tightly wound coil spring of
the sheath extension 36 and the proximal end of the tendon wire 5
are joined together. The swivel connector 39 is fastened to a lever
arm 41 and allowed to swivel about the connection point. The lever
arm 41, an axle 42, and an activation lever 23 make up the
deflection lever mechanism.
[0054] Movement of the activation lever 23 in one direction rotates
the axle 42, which in turn moves the lever arm 41 to pull on the
tendon wire 5 and the sheath extension 36. Movement of the lever
arm 41 in this direction imparts a proximally directed displacement
to both the tendon wire 5 and the proximal portion of the sheath
extension 35. This proximal displacement is transmitted down the
tendon wire 5 to the distal end of the distal flexible segment of
the catheter 16. The initial portion of the proximal displacement
works to compress the tightly wound coil of the sheath 18. The
sheath 18 stiffens and prevents any further proximal displacement,
and prevents compressive force from being transmitted to the
catheter shaft 63, thereby allowing all remaining displacement to
be used to effect a bending of the distal bendable segment of the
catheter 18. During activation of tip deflection, the sheath 18 and
the sheath extension 35 extending from the shaft union 15 in the
catheter 16 to the adjustment screw 44 in the handle 20 are under
compression. The sheath extension 36 extending from the proximal
side of the adjustment screw 44 to the lever arm 41 is under
tension.
[0055] Release of the activation lever 23 will cause the portion of
the sheath extension 36 which is extending from the proximal side
of the adjustment screw 44 to recoil and bring the lever mechanism
back to its initial position. This forces the tendon wire 5 toward
the catheter tip 1, and along with the assistance of the spine wire
4 and the elastic properties of the distal jacket tube 14, this
results in a straightening of the distal deflection segment of the
catheter 16. During activation of the deflection mechanism, the
service loop 37 in the sheath 18 inside the handle 20 allows the
catheter 16 to be bent without affecting tip deflection.
[0056] A locking or braking mechanism is employed on the deflection
lever mechanism to allow the user to set a desired level of tension
in the articulation mechanism to restrain the recoil action of the
sheath extension 36, and this level of tension will then be held
throughout the articulation of the tip. Also, by tightening the
brake knob 24, the tension level can even be set high enough to
lock the movement of the articulation mechanism to hold deflection
of the distal portion of the catheter 16 in any desired position
from 0 to 270 degrees. Tightening of the brake knob 24 imparts an
axial force to the tension shaft 64 by means of a metal threaded
insert (not shown) that is pressed into the brake knob 24. The two
tabs of the tension shaft 64 in turn apply compression to drag
washers (not shown). Reactive force generated by the drag washers
forces the lever shaft 42 against the side of the handle 20,
resisting rotation of the lever shaft 42.
[0057] Extending proximally from the handle 20 is a larger flexible
tube 25, the flex line, which houses the proximal portion of the
catheter shaft 63, the high pressure fluid line 29, and the gauge
line 22, as shown in FIGS. 2 and 6. In the preferred embodiment,
the flex line 25 is a corrugated tube constructed from a polymer
such as polyethylene. The distal end of the flex line 25 is
connected to the handle 20, and its proximal end is connected to a
gas line connector 27. Running essentially parallel within the flex
line 25 are the high pressure fluid line 29, the gauge line 22, and
a continuation of the catheter shaft 63, which is the low pressure
fluid line 47. The gauge line 22 exits the flex line 25 just distal
to the gas line connector 27 and terminates in a standard luer
fitting 30.
[0058] As shown in FIGS. 3, 4, and 5, the high pressure fluid line
29 and the low pressure fluid line 47 enter into and pass through
the gas line connector 27, with the low pressure line 47
terminating at the distal portion of a dual gas line fitting 28,
and with the high pressure fluid line 29 passing all the way
through the dual gas line fitting 28. The tubes of the low and high
pressure fluid lines 47,29 are potted to the gas line connector 27
to prevent fluid leakage. Where the low pressure fluid line 47
terminates, there are orifices 51 for the passage of fluid into a
mating receptacle (not shown). Just distal to these low pressure
orifices 51 is a quad o-ring 49 which prevents low pressure fluid
leakage when the dual gas line fitting 28 is inserted into a mating
receptacle (not shown). The high pressure fluid line 29 passes
through the cavity of the gas line connector 27 and through the
dual gas line fitting 28. At the proximal extremity is a check
valve actuator 53 which is actually a proximal extension of the
high pressure fluid line 29. High pressure orifices 52 are provided
in the proximal extension of the high pressure fluid line 29, to
allow for the passage of high pressure fluid into the high pressure
fluid line 29. A second quad o-ring 50 is located about the dual
gas line fitting 28 just distal to the high pressure orifices 52,
to prevent leakage of high pressure fluid when the dual gas line
fitting 28 is inserted into the mating receptacle (not shown).
[0059] The dual gas line fitting 28 has a mating and locking means
48 which allows the dual gas line fitting 28 to be securely
connected to the mating receptacle (not shown). The check valve
actuator 53 located most proximally on the dual gas line fitting 28
acts to open a check valve in the precooler assembly (not shown)
when the dual gas line fitting 28 is connected to the mating
receptacle (not shown). Conversely, disconnecting the dual gas line
fitting 28 from the mating receptacle (not shown) breaks contact
between the check valve actuator 53 and the check valve (not
shown), thus closing the check valve, minimizing gas escape from,
or pressure change within, the cryo refrigerant system.
[0060] While the particular invention as herein shown and disclosed
in detail is fully capable of obtaining the objects and providing
the advantages hereinbefore stated, it is to be understood that
this disclosure is merely illustrative of the presently preferred
embodiments of the invention and that no limitations are intended
other than as described in the appended claims.
* * * * *