Note: Descriptions are shown in the official language in which they were submitted.
11 ~ 1159739`
¦ Tit.le
DILATATION CA~HETER METHOD AND APPARATUS
Background of the Invention
_
The present invention relates to a method and apparatus
for use in dilating occluded blood vessels. The invention is
particularly concerned with such a method and apparatus wherein
dilatation is achieved through means of a balloon element which
is initially inverted within the distal end of a catheter and,
in use, extruded through and expanded within the occlusion being
treated. The invention is intended for use in treating either
~ arterial or venous occlusions.
,, Prior art efforts for the treatment of occluded blood
vessels have relied primarily upon the employment of bypass
~, vessels or some surgical technique whereby the occlusion is
physicially removed from the vessel being treated. Another
recent technique for treating occluded vessels relies upon the
insertion of some type of an instrument into the vessel to
,, dilate the occlusion through a stretching or compressing process.
The present invention is concerned with a technique of the latter
~20~ ~ type.
:
A principal problem with the employment of techniques
~wherein instruments are inserted into the vessel to effect
~,dilataticn by compression or stretching is that the instruments
~may damage the vessel and/or dislodge material therefrom.
25~ ~ Another problem with such techniques is that it has been very
~i difficult to place the instruments used therefor in highly
occluded or small diameter vessels. These problems have result~
primarily from the construction and size of the instruments. In
one~such technique, the instruments take the form of progres-
30~ ; sively larger catheters which are successively forced through
`" -`` 1 1~9739
the vessel being treated. In another technique, the instruments
have taken the form of an inflatable catheter which is forced
into place within the occluded area to be treated and, once in
p:Lace, inflated. These prior catheters, although flexible, are
S ¦ necessarily somewhat hard and inelastic, in order to enable the
catheter to be advanced large distances through the arterial
or venous systems. The inherent hardness of these catheters
contribute to the problems of vessel damage and material dis-
lodgement mentioned previously.
Summary of the Invention
The present invention relies on an apparatus and method
; wherein a highly flexible balloon is inverted within the distal
end of a flexible catheter and everted from the catheter for
extrusion through the occluded section of the vessel to be
lS treated. The b~lloon and catheter are so designed that the
balloon may symmetrically evert from the catheter and extrude
i through the occlusion in anisotropic fashion in advance ofsubstantial lateral expansion of the balloon. Eversion of the
balloon from the catheter is effected through means of the
application of internal fluid pressure to the catheter. Once
the balloon is in place within the occluded section of the
~; vessel, continued fluid pressure is applied to laterally expand
f ;~ the balloon and dilate the occlusion. The process of laterally
expanding the balloon to dilate the occlusion may be pulsed by
~25~ ~ repeatedly increasing and decreasing the fluid pressure within
1~ ~ the catheter. In the preferred embodiments, a cord element
: extends through the catheter and is connected to the balloon
to reinvert the balloon within the catheter after treatment of
^ the occlusion is complete.
~'~
3C A principal object of the invention is to provide an
inflatable catheter for use in dilating arterial or venous
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1S9~39
occlusions without injury to the vessel being treated or dis-
lodgment of material therefrom.
Another object is to provide an inflatable catheter
for use in dilating arterial or venous occlusions, such that a
a soft, inflatable dilating portion is advanced through the
occluded area in a gentle manner, with no need to force a hard
catheter through the occluded area prior to dilatation.
Another and more specific object is to provide such a
catheter wherein the inflatable element is initially inverted
within the end of the catheter and, upon being placed in close
proximity to the occlusion to be treated, everted for extrusion
through the occlusion in advance of substantial lateral expansion.
I
Still another object of the invention is to provide
such a catheter wherein the inflatable element is evertable from
the catheter in a syn~etrical fashion.
.
Yet another object of the invention is to provide such
a catheter wherein a mechanism is contained within the catheter
i for reinverting the inflatable element afterits expansion for
dilatation purposes.
Another objéct related to the latter object is to
provide such a mechanism which assures that the inflatable
element, or fragments thereof, cannot separate from the catheter.
Another object is to provide such a catheter wherein
the reinversion mechanism includes a secondary catheter extending
~ through the primary catheter and the inflatable element to enable
;¦ ~ the taking of pressure measurements or the making of injections
- without removal of the catheter from the vessel being treated.
~1
A further object of the invention is to provide an
I -- in1atable catheter which enables the dilatation of select
59~39
limited areas of the vessel being treated.
A further specific object of the invention is to
provide an inflatable dilatation catheter wherein the catheter
body may be of a diameter less than the lumen of the vessel being
t:reated and the inflatable element is initially inverted within
the distal end of the catheter.
A further object of the invention is to provide an
inflatable dilatation catheter which may be extruded into place
within an occluded section of the vessel being treated without
materially disturbing the occlusion and, once in place, may be
repeatedly laterally expanded and contracted to subject the
occlusion to pulsing dilatation.
The foregoing and other objects will become more
apparent when viewed in light of the following detailed descrip-
tion and accompanying drawings.
Brief Description of the Drawings
Fig. 1 is a perspective view illustrating an occluded
vessel in the process of being treated by a first embodiment of
the invention, with parts of the vessel broken away and shown in
section;
Fig. 2 is an elevational cross-sectional view illus-
trating the catheter of the first embodiment and a phantom line
representation of a vessel to be treated, as the catheter would
appear when being directed to an occluded section of the vessel;
Fig. 3 is a cross-sectional elevational view similar
to Fig. 2, illustrating the first embodiment catheter in associ-
atlon with a ~essel being treated, as the inflatable element
appears when first extruded through the occluded section of the
vessel;
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Fig. 4 is a cross-sectional elevational view, similar
to Fig. 3, illustrating the inflatable element, after it has
expanded to dilate the occlusion being treated;
Fig. 5 is a cross-sectional elevational view, similar
to Fig. 4, illustrating the inflatable element after completion
of the dilatation treatment and reinversion of the element into
the catheter;
Fig. 6 is a cross-sectional elevational view of a
second embodiment of the catheter with solid lines showing the
inflatable element in the inverted condition and phantom lines
showing the inflatable element in progressive stages of eversion
and lateral expansion;
Fig. 7 is a cross-sectional elevational view illustrat-
ing the catheter of a third embodiment of the invention and a
phantom line representation of a vessel to be treated, as the
catheter would appear when being directed to the occluded section
of the vessel;
Fig. 8 is a cross-sectional elevational view, similar
to Fig. 7, illustrating the third embodiment catheter in associa-
~ tion with a vessel being treatedJ as the inflatable element appear
when first extended through the occluded section of the vessel;
',
Fig. 9 is a cross-sectional elevational view, similar
; to Fig. 8, illustrating the third embodiment inflatable element
~- after it has expanded to dilate the occlusion being treated; and
Fig. lO is a cross-sectional elevational view, similar
to Fig. 9, illustrating the third embodiment inflatable element
after completion of the dilatation treatment and reinversion of
the element into the catheter.
~, . .
t
t` `~
` ~ 9 7 3 9
. Description of the First Embodiment
_
Fig. 1 illustrates a blood vessel 10 partially occluded
by an occlusion 12. As shown, the vessel takes the form of an
artery and the occlusion is what is commonly known as an arterio-
S sclerotic plaque or atheroma. This is the type of adhering
occlusion with which the inventive apparatus and method is
expected to find primary application. It should be understood,
I however, that the invention is applicable in treating other types
of occluded vessels wherein dilatation is desired. For example,
the invention may be used in treating occlusions resulting from
fibromuscular-dysplasia in veins.
The principal elements of the first embodiment apparatus
shown in Fig. 1 comprise: a flexible generally inelastic
catheter 14 fabricated of an inert polymer material such as
Dacron; a balloon element 16 fabricated of a highly elastic
resilient material, such as latex, said element having a mouth
portion (attachment ~shoulder~ 18 peripherally secured to the
distal end of the catheter 14 and a body portion 20 initially
inverted within the catheter; a cord 22 extending through the
20 ~ catheter 14 and connected at one end of the body portion 20 of
the balloon element; a syringe 24 connected to the proximate end
of the catheter 14 through an intermediate tubular coupling 26,
said syrin~e having a cylinder 28 with a positive displacement
piston plunger 30 sealinqly and slidably received therein, which
~,Z5 plunger has the proximate end of the cord 22 connected thereto;
-~ a flexible reservoir 32 removably connected in fluid communication
J :: ~ with the interior of the coupling 26 through means of a tubular
lateral extension 34 formed as part of the coupling; and a
selectively operable shut-off valve 36 interposed in the extension
;~ ~ 34. The catheter may ~ary in length, depending upon the applica-
I tion in which it is intended to be used, and commonly measures
~-l up to 30 inches in length. Cross-sectional dimensions of the
. ,.
~ - ~ 159~39
¦ catheter may vary,depending upon the application, and are
¦ generally chosen so that the outside diameter of the catheter is
¦ equal to about one-half the inner diameter of the nonoccluded
¦ lumen of the vessel being treated. In one typical embodiment, the
¦ catheter and associated balloon element have the following
¦ dimensions:
Catheter Body Dimensions
I
¦ O.D. : .085 inches
¦ I.D. : .060 inches
¦ Leng,h: Variable up to about 30 inches
¦ Balloon Element Dimensions When
Detached from Catheter
Reduced Diameter Body O.D.: .034 inches
Reduced Diameter Body I.D.: .020 inches
Reduced Diameter Body
Thickness : .007 inches
Attachment Shoulder O.D. : .14 inches
Attachment Shoulder
Thickness : .007 inches
Attachment Shoulder Length: .26 inches
; Attached Balloon Dimensions
Uninflated Inverted Length: .20 inches
Inflated Length After
Eversion : .70 inches
Inflated O.D. : .16 inches
~, In the preferred embodiment, the length, wall thickness, and O.D.
; ~ of the balloon element are such that the element does not drag on
-' the inner walls of the catheter when the element is everted out
of the catheter symmetrically. The balloon element should ideally
have a length no more than a~out 25 times the I.D. of the catheter .
The material and relative thicknesses of the balloon
. element are chosen so that expansion of the balloon element out
~;l of the end of the catheter takes place in anisotropic fashion
wi~h the element first eVerting but of the catheter in advance
of;~substantial lateral expansion and then, after eversion,
~5~39
laterally expanding in response to tne continued exertion of
fluid pressure internally of the catheter. Once everted out of
the catheter, the bal~oon element is designed to laterally expand
to an outside diameter equal to or greater than the I.D. of the
nonoccluded vessel being treated. Although such characteristics
may be achieved through the employment of an elastomeric balloon
element such as that of the foregoing example, it is anticipated
that similar characteristics may be achieved by fabricating the
balloon element of a folded generally inelastic flexible material
such as polyvinyl chloride, which is adapted to first evert to
an extended condition and then unfold to a laterally expanded
condition.
The cord 22 should be flexible and generally inelastic
and of such a length that it will not restrict eversion of the
balloonelement 16 as it is moved from the inverted condition
shown in Fig. 2 to the extended condition shown in Fig. 3. To
permit such unrestricted extension of the balloon element, the
cord is ideally provided with a slack portion, as shown in
the cylinder 28 illustrated in Fig. 2. The cord should also,
; 20 however, be of such a length that retraction of the plunger 30
beyond a predetermined limit functions to reinvert the balloon
element wlthin the distal end of the catheter, as shown in Fig. 5.
The catheter 14, syringe 24 and reservoir 32 contain
an incompressible fluid F. Preferably, this fluid is radiopague
in order to facilitate the radiographic monitoring of the
position of the catheter ana progress of the dilatation procedure.
The valve 36 provides means whereby this fluid may be selectively
captured between the balloon element 16 and the piston 30 (i.e.,
when the valve is closed) or permitted to charge into and out of
the reservoir 32 (i.e., when the valve 36 is open). In either
condition, however, the reservoir 32 assures that the catheter 14
8-
~9 i3~
is al~a~s filleo ~ith fluid Prior to the dilatation proceàure,
b~th the catheter and the reservoir are pul-ged of air and filled
with fluid. The reservoir is aetached from the ca.heter, both
portions are separately filled, and the reservoir ano catheter
are rea1:tached. With the valve in the open condition, as it
would be in the ~ig. 4 conaition, the piston plunaer 30 may be
re.racted to tension the cord 22 and, thus, draw the balloon
element 16 into the reinverted conditicn within the catheter.
With the yalve 36 closed, the piston plunger 3~ may be compressed
to subject the catheter 14 to internal pressure and, thus, evert
the balloon element out of the end of the catheter, as shown in
Fig- 3. In the preferred mode of operation, the piston plunger
30 is depressed to a predetermined degree prior to closing of the
valye 36 to provide for carefully controlled expansion of the
balloon element by depression of the plunger and zssure that the
cord 22 is slack throughout eversion of the balloon element out
o~ the catheter. Suitable indicia may be provided on .he syringe
24 to index the point of plunger travel at which the valve 36
should be closed. The preferred construction also includes a
shoulder 37 on the plunger 30 for abuiment with the end of the
cylinder 28 to limit inward movement of the plunger. -
In using the first embodiment catheter to practice themethoa of the present 1nvention, an incision is first made in
the vessel to one side of the occlusion to be treated and then
the distal end of the catheter 14 is introduced into the vessel
through the incision. The catheter is then fed through the vessel
¦ to position the distal end .hereof proxinlate one end of the
occlusion, as shown in Figs. 1 and 2. At or prior to this time,
the position of the plunger 30 is adjusted and the valve 36 is
closed. With the catheter so positioned and the plunger s~
conditioned, the next step is to apply pressure to the plunger,
as shown in ~ig. 3, to subject the ca heter to internal fluid
~ ,; "
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Il ~ 15~739
pressure and evert the body portion of the balloon element there-
from for extrusion through the occlusion 12. In the preferred
mode, during such eversion, the balloon element extends axially
without substantial lateral expansion. Once the balloon element
has extruded through the occlusion 12, the application of con-
tinued fluid to the catheter through the plunger 30 functions to
laterally expand the balloon element as shown in Fig. 4 and, thus,
dilate the occlusion. Such expansion and dilatation may be pulsed
by moving the plunger 30 in and out. Throughout the placement and
dilatation process, the progress of the treatment may be radio-
graphically monitored. The extent of stretching during the
dilatation process as a result of lateral expansion of the balloon
may vary somewhat, depending upon the circumstances involved.
Ideally, the balloon is expanded so as to have an outside diameter
equal to or slightly greater than the internal diameter of the
nonoccluded vessel.
Once the dilatation is complete, the valve 36 is opened
and the plunger 30 is retracted, as shown in Fig. 5, to tension
the cPrd 22 and, thus, reinvert the balloon element within the
catheter. At this point, the catheter may be removed from the
vessel, and the incision through which the catheter was introduced
may be closed. It is also possible, depending upon the circum-
stances involved, that the catheter may be moved into a further
section of the occlusion being treated, or on to a successive
occlusion prior to removal of the catheter. In such a case, the
balloon element would be everted and re-expanded, as shown in
~igs. 2, 3 and 4 for each successive dilatation treatment and,
ultimatel~, the balloon element would be reinverted and the
catheter removed from thé vessel.
Description of the Second Embodiment
The embodiment of Fig. 6 corresponds to that of the
first embodiment, with the exception that the balloon element,
' .~ .. . .
1 0 -
7 3 9
designated 16a, is not provided with a cord to draw it back into
the reinverted condition within the catheter, designated 14a.
Other than this difference, the structure and mode of operation of
the embodiment shown in Fig. 6 would be identical to that of the
first embodiment described in the foregoing discussion with respec
to ~igs. 1 to 5. with the Fig. 6 embodiment, reinversion is
achiev?d through means of the vacuum created within the catheter
14a by retraction of the plunger of the syringe ~not illustrated)
associated with the catheter 14a. It is also possible that the
Fig. 6 balloon element might be permitted to remain in the ex-
tended, but uninflated, condition during the course of removal of
the catheter 14a after a dilatation treatment. Once the catheter
14a is removed from the vessel being treated, external means could
be used to assist in reinversion of the balloon element.
Description of the Third Embodiment
The principal difference between the third embodiment,
illustrated in Figs. 7 to 10, and the first embodiment described
in the foregoing discussion with respect to Figs. 1 to 5 is that
the third embodiment employs an annular balloon element 16b in
place of the closed bulbous element 16, and a tubular cord element
in the form of a flexible catheter 22b in place of the simple cord
22. The purpose of these differences is to provide a passage
(i.e., the passage through the catheter 22b and the annular bal-
loon element 16b) through which pressure within the vessel being
treated may be measured, or injections into the vessel may be n,ade.
For the latter purpose, the plunger 30b (see Fig. 7) is provided
with a passage through which the catheter 22b extends and a syring~
38 is connected to the proximate end of the catheter 22b.
The vessel and occlusion depicted in Figs. 7 to 10
correspond to those of Figs. 1 to ~ and, accordingly, are desig-
nated by the numerals 10 and 12, respectively. The elements of
11 ~ 159739
the third embodiment catheter and inflating mechanism which
correspond to those of the first embodiment are designated in
Figs. 7 to 10 by numerals corresponding to those used in Figs. 1
to 5, as follows: catheter 14; syringe 24; tubular coupling 26;
cylinder 28; fleY.ible reservoir 32; tubular lateral extension 34;
and, shut-off valve 36.
The mouth portion (attachment shoulder) of the element
16b is designated 18b and the body portion of the element 16b is
designated 20b. In the preferred construction, the balloon
element 16b is fabricated of latex. The inner catheter 22b to
which the balloon element 16b is connected may be fabricated of
any suitable material, such as Dacron or polyvinyl chloride.
Ideally, the material from which the catheter 22b is fabricated
is flexible and generally inelastic.
; 15 Like the balloon element 16, the annular balloon
¦ element 16b is fabricated so that it may evert out of the end of
the catheter 14 in anisotropic fashion, with the balloon element
first everting out of the catheter in advance of substantial
lateral expansion and then, upon eversion, being laterally
expansible in response to the continued exertion of fluid
pressure internally of the catheter 14. The catheter 22b serves
a function similar to the cord 22 and should be flexible and
generally inelastic and of such a length that it will not restrict
ev~rsion of the balloon element 16b out of the catheter 14. To
permit such unrestricted extension of the element 16b, the
; catheter 22b is ideally provided with a slack portion, as shown
in the cylinder 28 in Fig. 7. The catheter 22b should also,
however, be of such a length that retraction of the plunger 3Ob
beyond a predetermined limit functions to reinvert the element
16b within the distal end of the catheter 14, as shown in Fig. 10.
~12-
~ 15973~
The third embodiment catheter 14, s~ringe 24 and
reserv~ir 32 contain an incompressible fluid F and operate, in
cooperation with the valve 36, in the same manner described in
the foregoing discussion with respect to the first embodiment.
A stop shoulder 37b, corresponding to the afore~escribed shoulder
37, is provided on the ~lunger 30b to limit inward movement of
the plunger relative to the cylinder 28.
'~he third embodiment catheter is used to practice the
method of ~he invention in essentially the same manner described
in the foregoing discussion with respect to the first embodiment.
During this use, an incision is first made in the vessel to one
side of the occlusion to be treated and then the distal end of
the catheter 14 is introduced into the vessel through the incision
~he catheter is then advanced through the vessel to a position
proximate one end of the occlusion and, once so positioned, the
plunger 30b is used to first evert the element 16b out of the
catheter 14 and through the occlusion and ,hen t~ exp~nd the
element 16b laterally to dilate the occlusion. As in the first
embodiment catheter, the element 16b is extruded through the
occlusion in advance of substantial lateral expansion of the
element. Expansion of the element for dilatation purposes may
be pulsed by moving the plunger 30b in and out and the progress
of dilatation may ~e radiographically monitored. The extent of
~; stretching during the dilatation process may vary somewhat,
depen~ing up~n the circumstances involved. Generally, the element
; 16b is expanded so as to have an outside diameter equal to or
slightly greater than the internal diameter of the nonoccluded
; section of the vessel being treated.
Figs. 7, 8, 9 and 10 show the successive steps in
practicing the invention. In Fig. 7, the catheter is shown as
, it would appear when being directed to the situs of the occlusion.
.
~ 13-
~59i3g
Fig. 8 sho~s the catheter as it would appear ~hen the element 16b
is initially expanded for extrusion through the occlusion. From
this figure, it will be seen that the catheter 22b is àra~n
through the occlusion with the element 16b and, thus, pro~ides
a pzssage through the element 16b. Fig. 9 sho~s the element 16b
as it would appear when inflated to dilate the occlusion 12.
In Pig. 10, thecatheter is shown in the condition it would assume
when tne valve 36 is opened and the plunger 30b is retracted to
tension the catheter 22b and, thus,reinvert the element 16b
within the catheter 14. With the element 16b so reinverted, the
catheter may be moved to another situs within the vesse- for
fur.her dilatation treatment, or removed from the vessel.
~ The lumen of the catheter 22b provides means whereby
injections or pressure mezsurement can be made while the third
embodiment catheter 14 is in place in a vessel. Such injections
or measurements can be made at any time as the lumen of the
catheter 22b remains open at all times.
'~
Conclusion
Although preferred embodiments of the invention have
; 20 been illustrated and described, it should be understood that
the invention is notintended to be limited to the specifics of
these embo~iments, but rather is definea by the accompanying
¦ -1aims
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