Note: Descriptions are shown in the official language in which they were submitted.
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~I THERAPEUTIC METHOD OF USE FOR MINIATURE DETACHABLE
BALLOON CATHETER
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; BACKGROUND OF THE INVENTION
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I The development of m~ure balloon catheters for use
¦in small tortuous locations such as neurological blood vessels
lis an extremely active and dynamic field. The development can
,~be traced through the work of Dr. Serbinenko of Russia
¦ as published in the Journal of Neurosurgery, Volume 41, August
1974, pages 125-1~5 and entitled Balloon Catherization and
Occlusion of Major Cerebral Vessels. An exa~ple of more
recent work in the area is present in U. S. Patent No. 4,085,757
issued to Dr. Paul H. Pevsner on April 25, 1978.
I¦ The rapid development of the art is readily apparent
¦! and the visible field of use becomes greater as experimental
iiwork continues within the medical profession. A variety of
jimproved designs for miniature balloon catheters for detachment,
perfusion and other purposes are being developed at rapid rate
jwith improvements being conceived constantly. Naturally
llproceeding hand-in-hand with the improved devices is a sequence
lof improved techniques in ~he use of balloon catheters both for
Ineurological purposes and for use in other boay vessels and
icavities.
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¦ Original developments in the use of detachable perfusio~,
I balloons were primarily directed toward the diagnosis and treat- !
¦¦ ment of neurological diseases; In certain instances larger
¦ non-detachable balloons have been utilized for emergency pre-
i ope~ative control of hemmorrhage in the abdominal circulation,
but most efforts have centered about therapeutic embolization
¦ with a variety of materials.
One particular area open for development is in the use
of the detachable balloon occlusion as offering a method for
jprecise and possibly long-term occlusion without the dangers
of inadvertent embolization associated with the injection of
particulate matter through a catheter. There is very little
data available describing the possible variables influencing
balloon occlusion.
ISU~MARY OF THE INVENTION
I With the above background in mind, it is among the
~primary objectives of the present invention to present a
technique for use of detachable balloons fox thexapeutic emboliza-
tion. The objective is accomplished by the consideration of the
osmolarity of radiopaque media used to fill the balloon~ A
description of the development of the present invention appears
in Radiology, Volume 126, No. 2, pages 521-523, published in
February 1978 and entitled Therapeutic Embolization With
~Detachable Balloons.
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I As pointed out in the ab~ve publication dealing with the
jsubject matter of the present invention, osmolarity pf the d~s~
tending con_rast media is an important variable influencing
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the permanency of ~alloon occlusion, particularly where the
balloon is of a semi-permeable material sych as a silicone
membrane commonly known as SILASTIC rubber. It is an objective to ~lse
a fluid to produce the desired conditions ~or long term
embolizations.
In utilizing a semi-permeable membrane material such as a
silicone material for the expandable balloon, for example a
SIL~ IC rubber balloon, the following compounds have been found
effecti~e to produce the desired osmolarity condltions ~particular-
ly for radiopaque contrast media. A first is R-60 manufactured
by Squibb, Inc., Princeton, New Jersey 08540 containing 60~ Na-
meglamine diatriæoate diluted to a 30 percent iodine con-
centration and identified as R-30. A second is METRIZAMIDE, a
non-ionic, fluid contrast medium manufactured by Sterling-
Winthrop Research Institute of Rensselaer, New ~ork 12144. A
third is Iodipamide Meglumine manufactured by Squibb, Inc.,
Princeton, New Jersey 08540 currently available for intro-
vascular use and nearly iso-osmotic ~hen diluted by 30% with
sterile water.
It is contemplated that in dealing with a silicone
balloon as the detachable member, it acts as a semi-permeable
membrane and permanency of the detached balloon inflation is
dependent on the osmolarity of the filling substance within the
volume limits of the detachable ba~loon.
In order to prevent premature or undue swelling and
rupturing as well as loss of radiopacacity of the balloon implant ,
a ra~iopaqu~ filler of similar osmolarity to blood is used. As
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a result, the longevity of the balloon is increased and a more
effective and better therapeutic embolization is achieved.
In summary, a therapeutic medical procedure is provided
utilizing a miniature balloon catheter of the type including a
resilient cannula adapted for attachmen~ to a source of fluid
and having a small outer diameter for insertion into small
vessels containing fluid. An inflatable balloon having a mouth
at the proximal end thereof is detachably mounted on the end of
the cannula in fluid communication therewith. Sealing means is
on the catheter to close the mouth of the balloon when the
cannula is detached therefrom. The procedure involves inserting
the balloon cathetex into a small vessel. The catheter is
advanced in the vessel to the desired location. The balloon
catheter is attached to a source of fluid having an osmolarity substantially
the same as the fluid in the vessel and being a contrast agent, and the
balloon is inflated with the fluid from the fluid source
traveling through the cannula until the balloon is fixed in
position in the vessel. The cannula is then detached from the
~alloon and removed from the vessel. The sealing means seals
the mouth of the inflated balloon with the fluid therein to ma~n
tain the balloon in inflated position for an éxtended period oE
time to create a vessel occlusion.
In another embo~iment, the invention pr~ des ~ balloon-
catheter assembly for use in a medical procedure which produces
embolization of a fluid-containing vessel comprising:
a resilient cannula having a proximal po~tion adapted for
connection to a source of external fluid, said cannula having an
outer diameter adapted for insertion into said fluid-containin~
vessel;
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an inflatable balloon member detachably connected by a
fluid-tight sealing arrangement to a distal portion of said
cannula, the interior of said balloon being in fluid
communication with said cannula for the reception of said
external fluid therein for inflating said balloon member
inside said vessel, said balloon member including an
inflatable portion made of an expandable semi-permeable
material;
a source of external fluid in sufficient quantity to
inflate said balloon member inside said vessel to cause
embolization of said vessel, said external fluid having its
osmolarity property substantially the same as the osmolarrity
of the fluid in the vessel and being a contrast agent; and
means for delivering said external fluid to said balloon
member to effectuate its inflation, whereby after said balloon
member is detached inside said vessel it is adapted to remain
inflated for long-term embolization of said vessel.
With the above objectives among others in mind,
reference is made to the attached drawings.
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I BRIEF DESCRIPTION OF THE DRAWINGS
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: ¦ In The Dr_wings~
¦ Figure 1 is a fragmentary sectional view of the
I catheter utilized in performing the medical procedure of the
. ¦ inv~ntion;
¦ ~ ~igure 2 is a fragmentary sectional view of the
¦ catheter inserted into a small vessel and partially expanded
by introduction of fluid so that the catheter is floated
. along with the liquia in the vessel to the desired location;
Figure 3 is a fragmentary sectional view thereof
with the balloon having been expanded to seal against the
walls of the vessel;
Figure 4 is a fragmentary sectional view thereof
with fluid being introduced to detach the balloon from the
cannula;
Figure 5 is a fragmentary sectional view thereof with
the cannula detached from the balloon and being removed
therefrom and the balloon sealed;
Figure 6 is a fragmentary sectional view thereof with
the cannula having been removed from the balloon and the
balloon being retained in sealed expanded position in the
vessel with flui~ therein to create a vessel occlusion.
DETAILE:D DESCRIPTION OF THE PREFERRED EMBODIMENTS
The miniature balloon catheter assembly 2D adaptable
2~ for use in the medical technique of the present invention is
shown in the drawings.
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It inclu~les a hollow cannula 22 of polyurethane material
or any conventional substitute therefor. One end of cannula 22
is adapted to be connected to a source of fluid in a conventional
manner. Mounted in the other end of cannula 22 is an enlarged
end 24 of a pin 26. The enlarged end 24 expands the end p~rtion
28 of the cannula so that a frictional fit is presented there-
between. The pin has a passageway 30 therethrough and a side
opening 32 adjacent the wider diameter portion 24. The smaller
end of the pin 30 is positioned within a self-sealing plug ~4
mounted in the open end portion 36 of an expandable balloon 38.
The balloon 38 can be formed of a conventional material such
as a semi-permeable membrane of silicone commonly known as
SILASTIC rubber. The end portion 36 of balloon 38 terminates in an
open mouth 40. The mouth 40 is expanded to frictionally seat
on the outer surface of expanded end portion 28 of cannula 22.
The end of pin 30 extends through plug 34 so that the opening 42
`at its forward end is in communication with the hollow interior
44 of the balloon 38. The passageway 30 through the pin 26
communicates with the hollow interior of cannula 22 and with the
interior of balloon 44 thereby providing a passageway for fluid
into the balloon.
Surrounding the portion of the balloon where the plug
34 is located on the exterior surface thereof i5 an elastic
band 46 of plastic or rubber material which assists in
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retaining the pin in the self-sealing plug and is utilized
to assist with the self-sealing plug in sealing the open
end of the balloon when the cannula and pin combination
is removed therefrom during detachment. A secondary small
chamber 48 between the end of the cannula 22 and the self-
sealing plug 34 communicates with side opening 32 and provides
the area for additional fluid utilized to expand end portion
36 of the balloon and facilitate withdrawal of the cannula and
pin therefrom during detachment.
The self-sealing plug 34 can be formed of any commonly
used self-sealing plastic or natural or synthetic rubber material.
Similarly, the pin 26 can be formed of a rigid plastic or a
metal substitute therefor.
In the steps of use, the catheter 20 is introduced
to the vessel. An introductory catheter is inserted
through the body into the vessel to provide a passageway for
catheter 20 and then the catheter is passed through the in-
troducing catheter until it is positioned within the vessel 50
as shown in Figure 2. The vessel 50 is filled with a fluid such
as blood 52 traveling in the direction shown by the arrow in
Figure 2. Radiopa~ue contrast media in the form of a fluid
having an osmolarity substantially the same as blood is then
introduced from a conventional fluid source into the hollow
interior of cannula 22 and accordingly through the passageway 30
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¦ in the pin 26 and into the hollow chamber 44 of balloon 38.
¦ Sufficient fluid is introduced to partially expand the balloon
¦ and facilitate its natural flotation as it is directed by the
¦ flowing blood, for example, in the vessel to the desired
5 - ¦ location.
¦ When the desired location is reached, as shown in
¦ Figure 3, further fluid from the fluid source is introduced
¦ preferably under pressure as before through the catheter
¦ assembly to further expand balloon 38 until the balloon seals
¦ against the inner wall 54 of Yessel 50.
¦ When a satisfactory seal has occurred, detachment is
¦ then initiated in the manner depicted in Figure 4. Further
¦ fluid from the.fluid source is introduced through the cannula
¦ and thepin and bacX pressure forces the fluid to exit through
¦ side opening 32 in the pin into small chamber 48. Expansion
¦ of the balloon portion surrounding small chamber 48 causes the
mouth portion 40 of the balloon to expand and detach from
~rictional engagement with expanded end portion 28 OL the
cannula. This permits the cannula and frictionally held
pin to withdraw from the balloon 38. Materials are chosen so
that the frictional engagement between the cannula and the pin
is greater than the frictional engagement between the self-
sealing plug 34 and thepin. Thus the pin will withdraw from
plug 34 and will detach with the cannula from the balloon 38.
2; Naturally the balloon engagement with the interior wall 54 of
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the vessel will retain the balloon in position while the,
cannula 22 and pin 26 are withdrawn therefrom. The arrow in
Figure 4 shows the direction of withdrawal of the cannula and
connected pin.
~s pin 26 is withdrawn from self-sealing member 34, the
self-sealing member 34 in cooperation with the surrou~ding
elastomeric string 46 will close and seal the open end of
balloon 38 in expanded condition with the fluid 51 therein,
as shown in Figure 5. The nature of the balloon filler fluid
~0 is such that with a semi-permeable membr`ane formed of a material
such as S~STIC r~r for the balloon, ex*ra cellular fluid ba~ng
the balloon, does not accummulate within the balloon because
there is no significant osmotic gradient. The chosen fluid
provides adequate opacification and prolonged occlusion is
possible, particularly if the balloons are not over-inflated at
. the time of embolization. The result is an effective vessel
occlusion with the use of a detachable balloon, as shown in
Figure 6.
Successful examples of the above procedure were carried
out with a number of catheter assemblies of the above discussed
type. Under local anesthesia via le~t carotid artery cut-down
and catherization,- balloons were detached into the hepatic,
gastrosplenic, renal, internal iliac and profunda femoral
arteries. ~ninflated balloons--l mm in outside diameter ~0.040
inches) were mounted on a 0.6 mm (0.023 inches) polyurethane
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catheter and introduced thr~ugh a five French polyethylene
catheter. The balloon catheter was injected through the
introducing catheter after coiling the former in a fifty ml.
syringe filled with fiushing solution. Once the balloon cathete3
emerged from the introducing catheter slight distention of the
balloon with radiopaque contrast media allowed flow direction of
the balloon to the final site of embolization.
In a number of balloon catheters introduced in the above
manner, a radiopaque contrast media of 60 percent sodium-
meglumine diatrozoate (R-60) in the amount of 0.15 to 0.2 ml.
was utilized to render the balloons radiopaque. In a further
selected number of balloons, R-60 was diluted to a 30 percent
ioaine concentration (R-30) with the addition of sterile water.
. ~ollow;ng balloon detachment in the above described manner,
post-occlusion angiography was performed via the introducing
catheter. The results were observed by serial radiographs
obtained over an extended period to demonstrate that, among
other factors~ that the osmolarity of the distending contrast
media is an important ~ariable influencing the permanency of
SILASTIC rubber balloon occlusion.
Sod~um-meglumate diatrozoate, in the concentrations
utilized, has osmolaritieS Of 1511 and 680 mOsm/l, which
are significantly higher than blood (27~-2g0 mOsm/11.
Silastic r~bber app~d to behave like any semi-p~able ~rane.
Extra cellular bathing the balloon crossed the Silastic r~
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membrane thereby reducing the osmotic gradient. These effects
were mu~h le-~s app~rent with R-30 than with R-60 solutions.
The tests also show that care should be taken not to over-
inflate the balloons at the time of embolization. The results
show that prolonged occlusion i5 possible with the technique
as described above.
It is suggested that contrast agents be employed
with osmolarities near that of blood. With this in mind,
another effective contrast agent is Cholografin Meglumine
manufactured by Squibb, Inc., of ~rinceton, New Jersey 08540.
The undiluted 52 percent Ioditamide Meglumine solution has an
iodine concentration of 260 mg. of iodine/ml and an
osmolality of ~30 milliosmoles/liter. This means that this
material can be diluted by one-third and achieve the same
radiopacity as Metri~amide at an osmolality which is just
slightly over that of blood. A series of ~n vitro measurements
of changes in osmolality were made after using dilute
Cholografin with balloons of the above type, showing essentially
no change in osmolality five days after the balloons were
placed in saline.
In summary, silicone behaves like a semi-permeable
membrane and permanency of detachable balloon inflation is
dependent on the osmolarity of the filling substance within
the volume limits of detachable balloons. Detachable balloons
f~lled with hyperosmotic contrast agents swell and lose
radiopacity. In testing with two contrast agents, one
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of1500 millisomoles/liter and the other with 691 milliosmoles/
,~ liter resulted in confirmation in vivo that balloon s~elling
occurred and there was decreased radiopacification on serial
radiographs. It was also determined that balloons filled
with the hypoersmotic contrast agents would rupture before
those filled with less osmotically active radio opaque filler.
Further confirmation of the importance of osmolarity
was determined by using ~etrizamide, an iso-osmotic contrast
agent. None of the experiments employing the rletrizamide
balloons ruptured after five months of observation. Testing
also confirmed in vitro that silicone is a semi-permeable
membrane. This was accomplished by placing balloons filled
with contrast agents of different os~olarity in saline and
measuring percent changes of 12 hours, 36 hours and 5 aa~s.
This confirmed conclusively in vitro that the osmolarities
fell in the balloons'filled with hyperosmotic contrast agents.
Thus, there was transfer of fluid across the semi-permeable
membrane which would, account for early rupture of balloons.
It was also observed that balloons filled with hyperosmotic
, 20 contrast agents would increase in size.
'Thus the several aforenoted objects and advantages are
most effecti~ely attained. Although several somewhat preferred
embodiments hav'e been disclosed and, described in detail herein,
it should be understood that this invention is in no sense
~5 limited thereby and its scope is to be determined by that of the
appended claims.
