U.S. patent number 3,773,034 [Application Number 05/201,912] was granted by the patent office on 1973-11-20 for steerable catheter.
This patent grant is currently assigned to ITT Research Institute. Invention is credited to Marvin Burns, Charles Thomas Ogden, Richard A. Rodzen.
United States Patent |
3,773,034 |
Burns , et al. |
November 20, 1973 |
**Please see images for:
( Certificate of Correction ) ** |
STEERABLE CATHETER
Abstract
A tip on a catheter is bent to steer the distal end of the
catheter by displacing a control fluid within an elongated fluid
conduit to stretch one longitudinally extending side of the tip
relative to an opposite longitudinally extending side of the tip.
The stretched side bends about the shorter side with a radius of
curvature larger than the radius of curvature for the shorter side
of the tip. A longitudinal restraining means may be applied to the
tip to assure that the tip always bends in the same direction with
the fluid displacement. On the other hand, other catheters may be
bent in several and predetermined directions by providing a
plurality of discrete fluid control conduits and by establishing a
fluid pressure differential in at least one of the conduits to
cause its associated side to lengthen and bend relative to a
portion of the tip associated with another control conduit. The
catheter may be small in dimension, made inexpensively and
restrained against expanding in diameter by a circumferential
restraining means.
Inventors: |
Burns; Marvin (Wilmette,
IL), Ogden; Charles Thomas (Chicago, IL), Rodzen; Richard
A. (Bollingbrook, IL) |
Assignee: |
ITT Research Institute
(Chicago, IL)
|
Family
ID: |
22747803 |
Appl.
No.: |
05/201,912 |
Filed: |
November 24, 1971 |
Current U.S.
Class: |
600/434;
604/95.01 |
Current CPC
Class: |
A61M
25/0155 (20130101) |
Current International
Class: |
A61M
25/01 (20060101); A61m 025/00 () |
Field of
Search: |
;128/4,6-8,348-351,356,DIG.9,2M,2R,2.5D,2.5R |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Truluck; Dalton L.
Claims
What is claimed is:
1. An elongated steerable catheter extending from a proximal to a
distal end for passing through channels defined by walls in a body,
said catheter comprising an elongated tube having a longitudinally
extending passageway therein extending from the proximal end to a
discharge opening adjacent the distal end, at least one control
conduit means receiving a control fluid associated with the
elongated tube and extending longitudinally from said proximal end
to said distal end, said distal end of said tube being formed of a
flexible, thin stretchable and contractible material for axial
elongation with increase in pressure in said control conduit means
and for contraction with reduction of said increase in pressure,
said catheter having a predetermined overall length and a
predetermined external cross-sectional dimension remaining
substantially unchanged with increase of pressure in said control
tube, and steering control means for displacing said control fluid
in said control conduit to cause one portion of said elongated tube
at the distal end of the catheter which is the least restrained by
the walls of the channel to stretch and to lengthen further into
said channel and relative to another portion of said elongated tube
which is more restrained by engagement with the walls of said
channels, said lengthened portion being free to bend about said
another portion in proportion to the pressure of control fluid and
at various locations dependent upon the location of the restraint
of said another portion so that tip may bend with varying radii
dependent upon the radii of the channel.
2. A catheter in accordance with claim 1 in which said control
conduit means is an inner tube having a hollow central passageway
and in which said elongated tube is an outer tube coaxial with said
inner tube and in which said passageway of said elongated tube is
annular in cross section, said discharge opening of said elongated
tube being radially directed and in said outer tube.
3. A catheter in accordance with claim 1 in which means are
provided in said distal end of said tube passageway to hold the
same against collapsing inwardly and closing said tube passageway
when bending the catheter distal end.
4. A catheter in accordance with claim 3 in which said means to
hold said tube passageway against collapsing is a coiled spring
inserted into said lumen at said distal end thereof.
5. A catheter in accordance with claim 3 in which a plurality of
longitudinal extending control conduits are spaced
circumferentially about said tube and in which said steering
control means is connected to each of said control conduits to
provide a pressure differential within and between said control
conduits to stretch said one portion of said tube thereby causing
said distal end to bend.
6. A catheter in accordance with claim 1 in which a circumferential
restraining means holds said control conduit means from a
substantial radially outward expansion with an increase of pressure
in said control conduit.
7. A catheter in accordance with claim 6 in which said
circumferential restraining means comprises helically wound wraps
of opposite lays which permit lengthening of one portion of the
distal end of the tube relative to the other portion.
8. An elongated steerable catheter extending from a proximal to a
distal end, said catheter comprising an elongated tube having a
longitudinally extending passageway therein extending from the
proximal end to a discharge opening adjacent the distal end, an
elongated control conduit for receiving a control fluid associated
with the elongated tube and extending longitudinally from said
proximal end to said distal end, a constraining means for
constraining one portion of said tube at said distal end against
lengthening longitudinally to the extent that another portion
lengthens under fluid pressure in said control conduit, and
steering control means for increasing the pressure of said control
fluid in said control conduit to elongate said other portion of
said tube relative to said one portion causing said distal end to
bend with said other portion having a larger radius of curvature
than the one portion of the tube. pg,17
9. An elongated catheter extending from a proximal end to a distal
end which is steerable in multiple directions, said catheter
comprising an elongated tube having a longitudinally extending
passageway therein extending from the proximal end to a discharge
opening adjacent the distal end, said distal end of said tube being
stretchable and contractible, a plurality of discrete
longitudinally extending control conduits spaced circumferentially
about said tube and extending from said proximal end to said distal
end, said control conduits being connected to said distal end of
said steerable catheter at circumferentially spaced positions for
stretching an associated portion of said distal end of said tube
with establishment of a differential fluid pressure and
displacement of fluid among said control conduits, and a steering
control means having a plurality of selectively operable pressure
increasing means each associated with one of said control conduits
for increasing the pressure of fluid in its associated discrete
control conduit for stretching its associated portion of the distal
end of said tube, selective operations of said pressure increasing
means establishing pressure differentials causing the tube distal
end to bend in different directions.
10. A catheter in accordance with claim 9 in which said control
conduits comprise three separate tubes each extending along and
secured about an outer wall for said elongated tube and in which a
restraining means is helically wound about said control tubes to
limit the radially outward expansion thereof with an increase in
fluid pressure within the respective ones of the control tubes.
11. A catheter in accordance with claim 10 in which means are
provided in said distal end of said tube passageway to hold the
same against collpsing inwardly and closing said tube passageway
when bending the catheter distal end.
12. An elongated steerable catheter extending from a proximal to a
distal end, said catheter comprising an elongated tube having a
longitudinally extending passageway therein extending from the
proximal end to a discharge opening adjacent the distal end, at
least one control conduit means receiving a control fluid
associated with the elongated tube and extending longitudinally
from said proximal end to said distal end, steering control means
for displacing said control fluid in said control conduit to cause
one portion of said elongated tube at the distal end of the
catheter to lengthen relative to another portion of said elongated
tube causing the distal end to bend with the lengthened portion
having a larger radius of curvature than the other portion of the
elongated tube, means in said distal end of said tube passageway
for holding the same against collapsing inwardly and closing said
tube passageway when bending the catheter distal end, and a
constraining means constraining said other portion of the tube
against lengthening longitudinally to the extent that said one
portion lengthens whereby the constrained other portion of the tube
is at the smaller inside radius of curvature for the bent end of
the catheter.
Description
This invention relates to catheters and more particularly to
catheters having distal ends which may be deflected or bent to
facilitate its introduction into or travel through channels within
the human body.
Physicians currently use catheters to therapeutically explore the
cardiovascular and veinous systems of the human body. The movement
of a catheter through the blood vessels within the human body to
probe deeply for a considerable depth or through branching vessels
requires that the tip of the catheter be steerable, that is,
bendable or deflectable to travel at an angle when a branch of the
blood vessel is reached. Usually, the catheter has a lumen, i.e., a
passageway therein, through which fluids or contrast media may be
transmitted or a medical instrumentality may be inserted. It will
be appreciated that the catheters must be extremely small in
diameter to move through the blood vessels and that the controls
therefore must also be relatively small if there is to be
sufficient space remaining for the lumen.
One presently known form of cathether having a steerable tip at the
distal end has several control wires running from the steerable tip
to a proximal end at which steering means are provided for
operating the control wires to bend the steerable tip. One
shortcoming of control wires is that they add considerable
stiffness to the catheter. Also, because the wire must be very
small in diameter and often are curved and are frictionally
retarded against movement while within the blood vessel, the wires
sometimes fail when forces are exerted thereon to steer the
same.
Steerable catheters heretofore have been relatively expensive and
definitely are not so inexpensive that they may be discarded after
use, as in the case with many disposable medical instruments.
In accordance with the present invention, the use of wires may be
dispensed with and the catheter may be steered by a fluid
displacement technique. That is, a displacement of fluid and a
change of fluid pressure within control passages within the
catheter is used to bend the tip to control its curvature for
movement through the blood vessels. Also, in accordance with
another aspect of the invention, the catheter may be made from
plastic materials and at sufficiently low cost as to be a
disposable instrument.
Accordingly, a general object of the invention is to provide a new
and improved steerable catheter.
Other objects and advantages of the invention will become apparent
from the following detailed description taken in connection with
the accompanying drawings in which:
FIG. 1 is a diagrammatic perspective view of a steerable catheter
embodying the novel features of the invention;
FIG. 2 is an enlarged elevational view of the steerable tip of the
catheter of FIG. 1 bent by fluid displacement;
FIG. 3 is a view of the tip shown in FIG. 2 with the tip
straightened;
FIG. 4 is an enlarged fragmentary view showing the fabrication of
the tip of FIG. 2;
FIG. 5 is a diagrammatic perspective view of a multi-directional
bendable tip constructed in accordance with a further embodiment of
the invention;
FIG. 6 is an enlarged cross-sectioned perspective view of the tip
of FIG. 5; and
FIG. 7 illustrates another embodiment of the invention.
As shown in the drawings for purposes of illustration, the
invention is embodied in a steerable catheter 11 comprising an
elongated flexible tubular member 12 having a steerable tip 14 at
its distal end. At the opposite end of the tubular member 12, a
steering control means 17 is provided for displacing fluid within a
control conduit means 19 (FIG. 2) associated with the tubular
member 12 and extending to the steerable tip 14 at which the
displacement of fluid results in one side of the steerable tip
being lengthened relative to the other side of the tip with the
result that the steerable tip bends.
More specifically, as best seen in FIG. 2, the steerable tip 14 is
formed of a stretchable material which is free to lengthen when
sufficient fluid force is applied to stretch one longitudinally
extending portion or side 20 of the tip relative to another or
opposite longitudinally extending area or side 21 causing the tip
to bend with its lengthened side 20 having a larger curvature and
with its shorter side 21 having a smaller curvature. The catheter
illustrated in FIGS. 1-4 is a unidirectional catheter with the side
21 constrained against lengthening by an axial restraint means 23
while the other side is free to lengthen. Additionally, a
circumferential restraining means 25 in the form of helically
wrapped bands or tapes 26 wound in opposite directions constrain
the tip against a substantial increase in diameter while the side
20 is lengthening. The catheter 11 illustrated in FIGS. 1-4 is
termed a unidirectional catheter in that it bends in the same and
only one direction; and hence it will be necessary to rotate the
entire tubular member 12 to turn the tip 14 if it is not already
positioned to bend toward the branch blood vessel into which it is
to be inserted.
A multi-directional steerable catheter 27, such as illustrated in
FIGS. 5 and 6, may be bent at various directions and with varying
amounts of curvature upon operation of the steerable control means
28 (FIG. 5) connected to several discrete lines 30, 31 and 32 of a
fluid control means 29 which also comprises several fluid control
tubes. By establishing a fluid pressure differential between the
control tubes and by displacing fluid in at least one of the
control tubes, a steerable tip 33 may be bent from a straight
position, as shown in solid lines in FIG. 5, to the bent position,
as shown in dotted lines in FIG. 5. The bending is accomplished in
general the same way as in the unidirectional catheter. That is, by
displacing fluid to lengthen one side of the tip relative to an
opposite side of the tip.
Referring first in greater detail to the unidirectional catheter 11
shown in FIGS. 1-4, it is formed with a pair of coaxial tubes
comprising an inner, elongated flexible tube 39 and an outer
concentric elongated flexible tube 41 formed of a flexible
elastomeric material such as a plastic. The innermost tube 39 has a
central lumen 43 through which test fluids or instrumentation may
be inserted at a proximal end 45 of the catheter. To form the
control conduit means 19 for the control fluid, the inner and outer
tubes 39 and 41 are joined together at a fluid tight juncture 47 at
a distal end 49 for the catheter to prevent the loss of control
fluid which is introduced between interior surface 51 of the outer
tube and exterior surface 53 of the innermost tube 39 and within an
annular control conduit passageway 55 therebetween.
A longitudinal restraint means 23 will assure that the steerable
tip 14 will bend in a predetermined and predictable direction; and
in this instance, the restraint means is in the form of a
longitudinally extending solid filament or cord 56 such as
illustrated in FIG. 4. The cord 56 is fastened to the outer side of
the outer tube 41, for example, by being disposed between an inner
wrap 57 of tape or cord 26 and an outer wrap 58 of a flat helically
wound dacron tape or cords 26. The helically wound wraps 57 and 58
of tape serve as a constraint against substantial enlargement of
the tip diameter with increased pressure of the fluid in the
passageway 55. The longitudinal restraint cord 56 is disposed
parallel to the longitudinal axes of the respective tubes 39 and 41
and extends substantially the length of the tip 14. To reduce the
thickness of the overlapping cords, a substantially circular
cross-sectioned cord 56 may be flattened into a more oval or flat
cross section by passing it through a nip of a pair of rollers.
With an increase in fluid pressure in the control passageway 55,
the pressure acts on the joined tube ends 47 and is longitudinally
directed to cause the unrestrained side 20 of the outer tube 41 to
lengthen appreciably relative to its other side 21 to which is
bound the restraint cord 56. This cord is bendable but does not
readily lengthen when placed in tension. The cord resists
elongation and the cord 56 is bound to the underlying tape wraps 57
and thereby to the side 21 of the outer tube 41 by the outer tape
wraps 58. Thus, when the tip bends, the restraining cord 56 will be
at the inner smaller diameter curve, as best seen in FIG. 2,
opposite the outer, larger diameter curve.
The steerable fluid control means 17 for displacing and increasing
the fluid pressure within the fluid control passageway 55 may be in
the form of a conventional syringe 61, as best seen in FIG. 1,
which has its discharge end attached to a tube 63 which has its
other end secured to the tubes 41 and 39 and disposed in fluid
communication with the annular fluid control passageway 55
therebetween. The syringe has a central barrel 65 containing a
supply of control liquid which is acted upon by a piston at the
inner end of the plunger 67. Thus, a pressing inwardly on the
plunger 67 increases the liquid pressure and displaces liquid from
the syringe as the liquid acting on the tip end wall 47 forces the
same forwardly with a stretching of the side 20 of the tube 41 and
a bending about the constrained side 21, such as to the position
shown in FIG. 2. With release of the syringe plunger 67, the liquid
pressure will be reduced inside the control passageway and the
stretched side 20 of the outer tube 41 will contract and straighten
to return and straighten the tip.
To assure that the lumen 43 remains open and doesn't collapse
during the bending of the tip 14, an internal circumferential
restraint in the form of a close wound coiled spring 71 may be
placed within the lumen 43 to support the interior wall of the
inner tube 43. Preferably, the spring is helically wound and made
of stainless steel and allows bending of the tip without collapsing
the inner tube and closing the central lumen. That is, the coils of
the spring resist the inward movement of the wall of tube 39 when
the pressure of the fluid is increased during bending. Stainless
steel is preferred for the spring to prevent contamination of the
fluid being injected into the blood vessel.
Turning now for a more detailed discussion of the multi-directional
catheter 27 described hereinafter in connection with FIGS. 5 and 6,
it is provided with a fluid control means having a plurality of
control passageways in the form of tubes 73, 74 and 75 (FIG. 6)
bonded along the exterior of an inner tube 77 having an inner lumen
79 through which a contrasting fluid or instrument may be inserted.
The control tubes 73, 74 and 75 are spaced circumferentially about
the outer surface of the innermost tube and bonded thereto at
equi-angularly spaced locations. The control tubes have closed ends
located at distal end 81 of the bendable tip 33 against which
pressurized liquid in the tube will exert longitudinally directed
forces to stretch the control tube and the underlying portion of
the inner tube 77.
To constrain the control tubes 73, 74 and 75 against enlarging
appreciably in diameter when fluid is displaced therein, the
control tubes are preferably overwrapped with oppositely disposed
lays of helically wound tape 83, of a thin flat dacron material.
The helical windings will allow bending and stretching of the inner
tube 77 and control tubes 73, 74 and 75 but constrain the latter
against substantial enlargement of the diameter thereof with
increase in pressure of the liquid during bending of the tip.
Preferably, the windings of tape are disposed side by side in each
lay to prevent the bulging of an expanded tube between adjacent
windings while still keeping the bulk of winding reduced.
Preferably, an elastomeric coating 85 of plastic is applied to
outer wraps of the tape 83 to impregnate the same and form a smooth
outer wall of plastic for the catheter tip 33. For example,
successive applications of urethane may be applied to impregnate
the tape windings and to build a plastic coating for the tip.
An internal circumferential restraint in the form of a close wound
coiled spring 78 may be placed within the lumen 79 to resist the
inward movement of the wall of the inner tube 77 when the pressure
of the fluid in the control tubes 73, 74 and 75 is increased during
the bending of the tip 33. Preferably, the spring is helically
wound and allows bending of the tip without collapsing the inner
tube and closing the lumen. Stainless steel is the preferred
material for the spring to prevent contamination of fluids being
injected into the blood vessel.
The steering control means 28 for the multi-directional catheter 27
may be of several types. For example, the illustrated steering
control means 28 comprises three syringes 91, 93 and 95 each
attached to one of the tubular line 30, 31 and 32 leading to and
connected in fluid communication with one of the control tubes 73,
74 and 75. By depressing inwardly on a plunger of one of the
syringes, fluid within its syringe barrel 96 may be placed under
increased pressure and displaced therefrom into its associated line
and control tube to cause stretching of its control tube and its
attached portion of the inner tube 77. A simultaneous operation of
two of the syringes to increase liquid pressure within two control
tubes causes the bending to occur along a path between the bending
positions caused with operation of only a single one of the
syringes.
A more compact steering control means 28 more readily operable with
one hand may be achieved by replacing the three individual syringes
with one pistol grip handle having three plunger operating triggers
or buttons incorporated therein for operation by each one of three
fingers gripping the handle. Then, either one or a combination of
two buttons may be depressed to increase pressure in attached fluid
control lines 30, 31 and 32 to cause the tip 33 of the
multi-directional catheter 27 to bend and steer in the desired
direction such as shown in dotted lines in FIG. 5.
The multi-directional catheter 27 having three control tubes 73, 74
and 75 has been found to be relatively stable and predictable as to
its direction of turning and may be operable with reasonable fluid
operating pressures. Multi-directional catheter have been made with
two control tubes (now shown) but they have not been found to
possess the stability and the predictability in turning that the
three tube multi-directional catheters possess. On the other hand,
increasing the number of control tubes from three to four has been
found to result in the necessity for a greater-operating fluid
pressure to cause bending because of increased frictional losses
due to the small size of the four individual control tubes. Thus,
the catheter with three control tubes is preferred.
While the illustrated multi-directional catheter 27 is fabricated
with separate fluid control tubes 73, 74 and 75 which are
individually preformed and then secured by adhesive to the inner
tube 77, reduced cost for the catheter may be achieved by
integrally molding the innermost tube and control fluid passageways
from a suitable plastic material. A one-piece molded catheter
having fluid control passages may be sufficiently low in cost to be
disposable.
In another smaller diameter embodiment of the invention, a
steerable tip 101, as best seen in FIG. 7, comprises a flexible
resilient tube 103 with a closed end 105 having a central control
conduit means in the form of a hollow interior passageway 107 in
the tube 103. A longitudinal restraint 109 is secured along the one
side of the tube 103 by a circumferential restraint which is formed
with opposed helical wraps of tape 111. The tube 103 extends to the
proximal end of the catheter for connection to a syringe (not
shown) of its associated steering control means. An outer
concentric tube 113 having a larger diameter is joined to the inner
tube 103 at a juncture wall 114 adjacent the steerable tip but
rearwardly thereof to form an annular passageway 115 extending
rearwardly to the proximal end of the tube. A series of apertures
117 are formed in the outer tube 113 adjacent the steerable tip for
allowing contrast media or catheter test fluid to be ejected from
the annular passageway 115. For example, such test fluids may be
supplied from a syringe (not shown) and forced through a line
extending therefrom to the annular passageway 115 whereby such test
fluid may flow from the apertures 117 adjacent the steerable tip.
The latter is bent when liquid under pressure from the steering
control syringe is forced through the central passageway 107 in the
inner conduit to stretch the side of the tip 101 opposite the
longitudinal restraint 109. As the steerable tip does not include
the outer tube 113, the outside diameter of the tip including the
circumferential wraps 111 may be kept smaller.
From the foregoing, it will be seen that the present invention is
directed to a fluid displacement steerable catheter which
eliminates the stiffness and frictional resistance of control wires
or the like used in prior art catheters. The fluid displacement
catheter may be made with relatively inexpensive flexible,
resilient plastic tubes or flexible, resilient elastomeric material
molded in one piece. The desired degree and direction of bending of
the tip may be attained by controlling the amount of fluid
displaced and the pressure exerted on one longitudinal side of the
tip relative to another longitudinal side thereof. Additionally,
the catheter may be made with dimensions sufficiently small to pass
through blood vessels and still provide a lumen for the injection
of contrasting media or instrumentation into the human body.
While a preferred embodiment has been shown and described, it will
be understood that there is no intent to limit the invention by
such disclosure but, rather, it is intended to cover all
modifications and alternate constructions falling within the spirit
and scope of the invention as defined in the appended claims.
* * * * *