CA1122494A

CA1122494A - Miniature balloon catheter method and apparatus

Info

Publication number: CA1122494A
Application number: CA301,833A
Authority: CA
Inventors: Paul H. Pevsner
Original assignee: Individual
Current assignee: Individual
Priority date: 1977-09-15
Filing date: 1978-04-24
Publication date: 1982-04-27
Also published as: US4213461A; DE2817972A1; GB1603151A; JPS5454487A; JPH0339705B2; SE7804664L

Abstract

ABSTRACT

A miniaturized balloon catheter assembly includes a cannula and an inflatable tubular balloon constructed of a silastic tubing detachably mounted on the cannula for performing a surgical procedure in an animal vessel, especially a human vessel in response to pressure therein. In one embodiment, the balloon is detachably mounted with the detachability being responsive to pressure. In another embodiment, a valve, such as a pin-hole in the silastic material for example, is included in the balloon which opens only after the pressure within the balloon exceeds a pre-determined amount.
According to a method of the invention, the cannula and the attached balloon are inserted into a small vessel and the balloon is pressurized therethrough. The balloon is partially inflated to allow fluid flow in the vessel to position the balloon at a desired location. Pressure is thereafter increased in the balloon to activate a desired procedure within the vessel. In the first embodiment the desired procedure is to withdraw the cannulla from the affixed balloon as the increased pressure lubricates the connection between the balloon and the cannula. In the second embodiment, the desired procedure is for the increased pressure to open the pin-hole and disperse a fluid into the vessel from the balloon.

Description

~L'2'~ 4 BACKGROU~D OF THE INVENTION
This invention relates broadly to the art of balloon catheters, an~ more particularly to the art of miniaturi~ed balloon catheters generally for use in blood vessels and the like.
A significant publication disclosing prior art developments in the area of this invention i5 Serbinenko, ~- Balloon Catheterizatlon and Occlusion of Major Cerebral Vessels, Journal of Neurosurgery, Volume 41, August, 1974, pages 125-145. Thls article describes the work of Dr.
Serblnenko with miniaturi~ed balloon cathetersO Dr. Serbinenko has employed balloon catheters to occlude vessels in cardio-vascular surgery as well as for other purposes~ and his article is incorporated by reference here.
Dr. Serbinenko employs a latex balloon that is held onto a cannula by means of an elastic string for achieving permanent occlusion of vessels. The balloon is inserted into a vessel and allowed to move to a proper position by fluid circulation within the vessel. The balloon is then inflated by means of a solidlfylng filler until it is fixed against the. walls of the vessel. ~fter the solidifying filler has solidified the cannula is pulled from the balloon and the balloon is left in the vessel.
A difficulty with Dr. Serbinenko's arrangement is that the balloon sometimes comes off of the cannula prematurely because the elastic string does not tightly hold the balloon to the cannula. Still another difficulty with Dr. Serbinenko's arrangement is that the solidifying filler is somewhat difficult and awkward to work with. Thus, it is an object of this invention to provide a miniaturized balloon catheter ~k .

which can be used for permanen-t occlusion of a vessel but which is not prematurely detached from the cannula and which can be inflated by a nonsolidifying fluid.
Dr. Serbinenko has also employed a minia-turized balloon catheter to achieve perfusion. That is, Dr. Serbinenko has made a hole in his latex balloon from which dye or the like is discharged from the balloon into the vessel. However, in Dr. Serbinenko~s arrangement, the fluid to be perfused passes through the hole as soon as the fluid enters the balloon. It is sometimes desirable that the fluid not pass through the hole until it is remotely controlled to do so.
Thus, it is another object of this invention -to provide a miniaturized balloon catheter which does not initiate perfusion of fluid until the balloon is remotely controlled to do so.
It is a further object of this inven-tion to provide a miniaturi2ed balloon catheter, and a method for using -the miniaturized balloon catheter which is efficient in operation, and relatively easy and inexpensive to manufacture.

SUMMARY
According to principles of one aspect of this invention, a miniaturized balloon catheter is inflated within a vessel until it is fixed against the walls of the vessels, and thereafter released from its attached cannula and sealed off against deflation. In this respect, the mechan:ism for attaching the balloon catheter to the cannula responds to increased pressure within the balloon once the balloon is fixed to release the balloon from the cannula so that the cannula can be pulled from the balloon and there-after closes the opening in the balloon left by the extracted :
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~, , gL94 cannula.
Also in accordance with principles of another aspect of this invention, additiona7 pressure within the balloon opens a valve in the balloon to disperse fluid from the balloon into the vessel for perfusion. This valve, in one embodimentJ comprises a pin-hole in the self-sealing silastic balloon.
Additional arrangements for performing the above functions are also described herèin.
To summarize, in general, the method and device of this invention deals w1th a miniaturized balloon catheter assembly adapted for use in diagnosis and therapy pxocedures in connection with small animal vessels, particular:Ly human vessels. The device includes a cannula having a small outer `~ diameter for insertion into small animal vessels. An inflatable balloon is mounted on the end o~ the cannula t~at i5 inserted into the vessel. The cannula and balloon are adapted to be carried by fluid in the vessel to a desired location therein. The force of pressure operates at the other end of the cannula to inflate the balloon. The balloon includes elements for responding to increased pressure therein to initiate desired diagnostic and/or therapy procedures within the vessel at the desired :

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location.
BRIEF DESCRIPTION OF T~E D?~7INGS
The foregoing and other objects, features and advantages of the invention will be apparent from ~he following more particular description of preferred embodi-ments of the invention, as illustrated in the accompanying drawings in which reference characters refer to the same part6 throughout the .~ifferent views. Tne drawings are not necessarily to scale, emphasis instead being placed upon ~ -. illustrating the principles of the in~ention in a clear manner.
: FIG. 1 is a plan vie~ or a ballvon ca-theter assembly .of the invention;
FIG. 2 is a sectional vie~ taken on line ~-2 of FIG~
~: FIG. 3 is an enlarged fragmentary plan view of the ; balloon catheter assembly o~f E~.~ure 1 showing an inflatable balloon portion attached to the end of a canrula;
FIG. 4 i~. an enlarged fragmentary view of the ~o balloon catheter assembly.of Figure 1 showing a modified form : of inflatable balloon portion attached to the e~d of the cannula;
FIG. 5 is a partial sectional view of an alternate form of the balloon catheter assembly of the invention showiny only the end por~ion of the cannula which is attache~
to the balloon portion;
FIG. 6 is a partial seciional view of the alternate arrangement of the balloon cathe~er of FIG. 5 with a wire by ~hich detachment at any balloon size may be achieved;
FIG. 7 is a sectional Vie~J of a further alterna~ive form of the .balloon catheter of the inven~ion;
.
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EIGS. 8-12 are sequential schematic represen-tations of the use of the types of devices depicted in FIGS. 1-4;
FIG. 13 is a schematic representation of the use of a balloon catheter of this invention for achievinc~ per-fusion;
FIG. 14 is a cross-sectional view of a mandril for making a perfusion-type balloon catheter having a balloon mounted thereon positioned above a liquid silicon rubber container or vat;
FIG. 15 is a fragmented cross-seetional side view of a perfusion-type balloon catheter constructed with the mandril of FIG. 14; and, FIG. 16 is a schematie representation of the use of a balloon catheter of this invention for achieving per-fusion in another mode of operation.
DESCRIPTION OF PREFERRED EMBODIMENTS
FIGS. 1 and 2 show a catheter assembly 20 which includes a hollow cannula 22, open at both ends, with a connector 24 at one end which is adapted for conneetion to a conventional source of pressurized fluid. Mounted on the other open end of the cannula 22 is an inflatable balloon portion or in~latable tube 26 as a self-sealing material described further below~ The distal end 28 of the balloon portion is closed by knotting the end. The proximal end 30 is expanded to cover and frictionally engac~e the adjacent end of the cannula 22. In this respect, in a preferred embodiment the interior diameters of both the balloon or tube portion 26 and the hollow cannula 22 are approximately 30 0.011 inch and the outer diameters thereof are 0.024 inch.

Thus, the balloon or tube portion 26 contracts onto the hollow cannula 22. This brings the passageway in the cannula 22 in communication with the interior passage o~ the inflatable balloon portion or tube 26. As shown in FIG.3 , the inflatable tube 26 has a pin-hole 32 adjacent to the distal end 2B which is normally closed when the balloon port.ion 26 is in the relaxed, uninflated condition since the material of the balloon is self-sealing. This hole could also be in the distal end 28. Again this is accomplished by forming the balloon portion 26 of an elastomeric self-sealing material such as silastic tubin~. -12 PIG. 4 shows an alternative means for forming the ~ ~ ~32 ~ ~

distal end of the balloon portion 26. In place of the knot at the end 28, a plug 34 attached by an adhesive is employed.
It is also contemplated in a further modification (not shown) that in place of a pin-hole 32, an opening could be positioned through the knot or the plug 34. The pin-hole 32 forms a passageway for fluid to pass from the distal end of the balloon portion 26 once the pressure within the balloon portions exceeds a predetermined amount.
Materials which can be used for the components of catheter 20 are, for cannula 22, a plastic such as polyethylene or an~ conventional substitute therefor; and, for the expand-ible balloon portion 26, silastic tubiny.
In addition to balloon portion 26 contracting onto the hollow cannula 22, a C-shaped spring 33 is mounted on the outside o the balloon portion to positively hold the balloon portion 26 and the hollow cannula 22 together. The C-shaped spring is constructed of a watch-spring metal and, in a preferred ~ ~odiment, this spring has a contracted internal diameter of 0.018 inches and an outside diameter of 0.020 inchssu When the spring has expanded, it has an inside diameter of 0.028 inches and an outside diameter of 0.033 inches. These dimensions of the C-spring cooperate with those of the balloon portion 26 such that when the cannula 22 is not positioned within the C-spring 33 then the opening to the balloon portion 26, which the cannula 22 held open, is closed ~y the C-spring.
FIG. 5 depicts an alternate device which is used as a detachable implant device for permanent vessel occluslon, for example. The mater~als used for cannula 22a and inflatable balloon portion 26. are the same as in the previously discussed embodiments and the difference in structure resides in the ~.

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interconnection between portion 26a and cannula 22a. In place of the expanded frictional interengagement, a combina-tion type structure is employed. In this reyard, a proximal end 36 of inflatable portion 26a is expanded in the same manner and coupled with the outer surface of cannula 22a.
Spaced from end 36 on portion 26a is an expandable ring 38 which is concentrically aligned with an inner plug 40. The plug is of an expandable elastomeric self-sealing material and is provided with a small pin-hole that may be formed by a wire or it may be pi~rced ~y a hollow pin 42 located within inflatable portion 26au Pin 42 has a through passage-way 44 which communicates at one end with the through passa~e-way 46 of cannula 22a and at the other communicates with the chamber 4S in the main body portion of inflatable balloon : 26a. This communication is accomplished by passing the ! pointed tip 50 of pin 42 through plug 4Q so that its open tip is .in communication from cannula 22 to the chamber 48 in balloon 26a.
An additional element o~ structure on pin 42 is a side opening 52 located between plug 40 and the end of cannula ~2a. This side opening is utilized for activa-ting the detachment bet~een inflatable portion,~6a and cannula 22a as will be described in detail below in connection with FIGSo 8-12. The through passageway is provided so tha~ the fluid from the pressure source can pass into the inflatable portion and inflate balloon 26a. The FIG. 5 embo~iment is perhaps cheaper to manufacture than the FIGS. 1-4 embo~iments.
The embodirnent of FIG. 6 is the same as the FIG. 5 embodiment with the exception of an additional wire 41 which passes through the through-passageway and terminates in a , ~

stop at the end in the form of a sphere 43. Naturally other configurations for the stop can be readily contemplated.
The wire is of smaller character than the passageway so that fluid can bypass the wire and inflation can occur to the desired degree. Then the wire can be withdrawn to block the open end of tip 50 by engagement with stop 43 which closes the opening. Therea~ter, further pressure will only be able to exit through side opening 52 to accomplish detachment.
In this manner, no further expansion of the balloon occurs during the detachment procedure. All fluid passes through the side opening.
The embodiments of FIGS. 5 and 6 do not have the pin-hole at the distal end of portion 26a for perfusion of material contained therein. However, it is contemplated that a passageway can be provided as is present in the embodiments of FIGS. 1-4 so that the combination of detachable means and perfusion means is present in the same device.
Turning to operation of the embodiments of FIGS.
1 6, reference is made to FIGS. 8-12. It should be noted at the outset that it is possible ~or the device to be initially introduced into a human vessel 54 by first passing a catheter of larger diameter into the vessel and then passing the cannula 20 or 2Oa through the larger catheter into the vessel 54. The larger catheter can then be removed or retained in position during the remainder of the operable procedures. It is contemplated that the larger catheter through which the device can be passed can be used with all of the discussed embodiments.
Naturally the dimensions of the balloon catheter assembly are a matter of choice depending upon the particular ~:~z~

animal vessel to which it is to be applied, keeping in mind, that the device is to be used particularly in very small human vessels. In any event, the length and lateral dimensions are determined by use. In addition to expanding the balloon portion to engage the outer surface of the end of the cannula, it is also possible to sh.rink the end of the balloon portion on the end of the cannula to produce the same result.
Turning to operation of cannula 20, FIG. 8 shows the cannula 20 in position in the small human vessel 54 prior to introduction of pressured fluid to expand portion 26.
. A first amount of pressurized fluid is then introduced as shown in FIG. 9 so as to partially expand halloon portion 26~ This increases the lateral dimension of the assembly and gains the ~: assistance of blood flowing through the vessel to push the :~ assembly along through the vessel until it reaches the desired operable location. At that point, as shown in FIG. 10, i further pressurized fluid is passed into the assembly so as to expand balloon 26 until it engages with the inner wall 56 of the vessel 54 and becomes fixed in position, Thereafter, as shown in FIG, 11, a third stage of further pressurized fluid is passed through cannula 22, Since further expansion of balloon 26 is retarded the further fluid tries to pass between the balloon portion 26 and the cannula 22 under the C-spring 33. The passage of this fluid lubricates the connection between balloon 26 and the cannula 22 so that the cannula 22 can be relatively easily withdrawn from the balloon 26.
A similar procedure is followed for the embodiment of FIGS. 5 and 6 wherein once the balloon is fixed within ~ 11 -the vessel so that further expansion OL the balloon 26 is retarded, fluid passes through side openirlg 52 in the pin 42 and expands the proximal end portion of balloon 26a whic~ is between band 38 and the proximal tip including portion 36.
This expansion of portion 36 frees it from en~agement with cannula 22a and permits cannula 22a and pin 42 to be withdra~n from inflatable portion 26a. There is minimal resis~ance between ~ip 50 and plug 40 due to the nature of the material .
:: of plug 40 or the prepositioned hole thexein and the t~pered tip 50 of the pin 42. The cannula 22a and pin 42 can thus be removed from the assembly and ~rom the vessel 54 leaviny ~ the inflatable portion 26a in posi~ion as an implant~
: Once pin 42 has been removed from plug 40 the self-sealing naturP of plug 40 or the resilience of outer band 38 or both cause the plug 40 to close the openin~
therethrough thereby forming a valve ~eans to seal the inflated balloon portion 26a and retain it in expanded position in proper location in the vessel.
Operation of the perfusion embodiment is depiGted

2~ in FIG. 13. Introduction and positioning of assembl~ 20 is accomplished in the same manner depicted in FIGS. ~-10.
Thereafter the third stage is reached at which additional fluid is introduced throu~h cannula 22 rrom the fluid source and, since in~latable por-tion 26 is retarded from further expansior., the fluid forces a medica~ment or r~diopa~ue dye, contained within the balloon portion 26, out throuyh o~eniny 32 in the end of bod~ 26. Sinc~ body 26 ~als the vessel at the point of its location the d~e is not diluted b.y blood at the upstream end of the vessel and accordin~y is fully e fective in use at the point of perfusion -~ ~ -12-~ .

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~ s discussed above, the device can be a combination of the one depicted in use in FIGS . 8-12 and the one depicted in use in FIG. 13 so that perfusion can be produced and detachment achieved with perfusion continuing after the implant is made for a length of time.
FIG. 7 of the drawings shows a further embodiment of the present invention wherein a balloon catheter 60 is designed for non-detachable use and, in particular, for ;~ perfusion. The balloon portlon 62 is friction fit over the open end of the cannula 64 for introduction of fluid. The - friction fit can be accomplished as in previous embodiments by a shrink fit between the parts or expanding the elastomeric balloon portion until it frictionally engages with the outer surface of catheter 64. The opposite end of the balloon ~ portion has a plug 66 of self-sealing elastomeric material ;~ such as silastic with a passageway 68 therethrough normally closed in view of the nature of the material of plug 66.
Sufficient introduction of fluid into balloon portion 62 will expand th~ balloon portion and eventually provide sufficient pressure to cause the elastomeric plug 66 to open passageway 68 and permit per~usion of the material contained within the balloon portion to be expelled downstream. It is possible to put the opening in the balloon portion at the end as shown in FIG. 7 or as a simple pin hole (not shown) in the end as shown in FIG. 5 or in the side as shown in FIGS. I-

3 or even in the rear end portion for introduction of material from the balloon portion upstream of its location.
It is also contemplated that the introduc' on catheter fo the embodiment shown can be of the double lumen 3Q type. That is, one lumen is directed into the balloon portion of the catheter assembly for introduction of fluid ~ - .

~ ~- A ~ ., ~ ~._ L t and expansion of ~he balloon portion; and, the other lumen is for introduc-tion o~ fluid into the area of attachment between the balloon portion o~ the catheter. In this manner the connection portion is expanded and detachment. o~ the components is accomplished so that the balloon portion.
remains as an implant. Wi-th the double lumen design, i-t is possible to retain a predetermined expansion level of the balloon portion since further expansion will not occur when fluid is passed only through the second lwmen which opens into the area fvr detachment only and not into the balloon portion.
FIGS. 14 and lS deplct an apparatus and method for constructing a perfusion balloon similar to the one o FIG. 7. In this respect, a steel mandril 80 on which a balloon 82 of silicon rukber, or silastic material, is molded, has an indentatlon 84 in ~he end thereofO A 0.001 inch diameter steel wire or pin 8~ is part of the mandril and protrudes outwardly from the main body of the mandril at approximately the center o~ ~he indenta~ion ~4O

To make the balloon 82, the mandril 80 is dipped into a container or vat 88 of liquid silastic material, or silicon rubber, 90 and then pulled out. In this respect, the s.ilicon rubber :;s dissolved in a solvent such as ether, para-chlor-benzene, Toluene , etc~ to put it in a liquid form. When the mandril æo is pulled out of the liquid silastic material 90 a residue, or dispersion, o~ molten material is le~t on the mandril, with the residue at the inaentation B4 being thicker than the xemainder thexeof. The 29 liquid silastic material is then chemically hardened (by

4 ~ ' allowing the solvent to evaporate) on the mandril to form the balloon 82. The resilient balloon 82 is then pulled ~ff the mandril 80. The thicker portion of the silicon rubber forms a reinforced plug 92 having a passageway or hole 94 therethrough formed by the pin 86. The hole 94 has a diameter of approximately 0.001 inch, which is so - small that, for silastic material, it is effec-tivel~ closed to the passage of water-soluble fluids which are to be perfused from the balloon such as contrast media, etc.
~owever, when the balloon is placed under pressure, ~he hole 94 opens at a predetermined pressure to allow fluid to pass from the balloon throu~h the hole. In this respect, the size of the balloon at which the hole ~4 opens to allow fluid passage is not only determined by the breadth and depth o~ the plug 92, but also by the wall thickness and length of the balloon. For example, in one embodiment the outer diameter of the balloon is approximately 0.02-0~036 inch, the inner diameter of the balloon is approximately 0~00~-0.01 inch, the balloon thickness is approximately 0.~05 inch, the balloon length is approximately 0.2 inch, the plug has a width of approximatel~ 0.006-0.007 inch and a depth of approximately 0.05 inch into the balloon. In this specific embodiment the internal balloon pressure required to open the hole 94 is appro~irnately 25 psiguage.
The pressure in the balloon will normally not reach th;s level until it has expanded against the sides of a vessel as is depicted in FIG. 13. However, in some cases it is desired that the hole 94 opens and that the balloon perfuses fluid wi~hout occluding the blood vessel. This can be accomplished with the above-mentioned speci~ic emhodiment ` 1 if the thickness of the balloon ~lalls are approximately doubled, with the other dimensions remaining the sa~e.
In this case, the balloon will perfuse through the hole 94 withou-t the balloon walls becoming wedged against the blood ~ ~essel walls as is depicted in PIG. 16.
; To make the above-descrlbed balloon, the mandril is made of steel and has a width of approximately 0.00~-Q.01 inch. The indentation 84 has a breadth, or width, of approximately 0.006-0.007 inch, and a depth of approximately 100.05 inch to determine the size of the plug 92. The steel pin 86 has a round cross-section with a diameter of 0.001 inch. It is possible and sometimes desirable to coat the mandril including the pin, or wir~, ~6, with Teflon* h~wever it is dlfficult to do this and maintain the small diameter necessary for the pin. Such coating is not necessaryO
! It will be appreciated by those skilled i~ the art that the reinforced plugs described herein, form effective ~alves which are actuated by sufficient pressure within the balloons to perfuse fluid into ~lood vessels at predetermined and uniform pressures and balloon siæes, as was previous~y described.
It is noted that it is possible to cut or puncture the hole 94 i.n the balloon, but it is difficult to maintain the proper tolerance of hole size in this manner. Further, such cut holes are ofterl too large. In any case, it is difficult, and possibly impossible, ko construct balloon catheters in this manner which will uniformly perfuse at predetermined pressure~. Such balloon catheters cannot be 29 counted on to function uniformly.

* Trade mark .

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l~hus, the several aforenoted objects and advan-tages are most effectively attained. Although several somewhat preferred embodiments have been disclosed and described in detail herein, it should be understood that this inventicn is in no sense limited thereby and its scope is tc be determined by that of the appended claims.

, , .

Claims

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A miniaturized balloon catheter assembly for use in small vessels comprising:
a cannula having proximal and distal ends including an attaching means at the proximal end thereof for attaching to a source of pressurized fluid and having a small outer diameter for insertion into small vessels;
an inflatable balloon including a means forming a mouth at a proximal end thereof mounted on an external surface of the cannula at the distal end of the cannula to be in fluid communication therewith, the cannula and balloon together adapted to be carried by the fluid in a vessel to desired locations therein, whereupon attachment of the cannula fluid source of pressurized fluid and intro-duction of amounts of pressurized fluid flow inflate the balloon to fix it in position against the wall of said vessel at a desired location; and, a balloon-retaining means responsive to a predetermined further amount of pressure to initiate a desired procedure within the small vessels, said balloon-retaining means including a resilient contracting member surrounding said means forming said mouth for holding said means forming said mouth on said external surface of said cannula, said resilient contracting member being constructed to have a specific predetermined internal size when in a contracted state for: contracting with a uniform prede-termined tension about said means forming said mouth when said means forming said mouth is mounted on said cannula to hold said balloon on said cannula upon said balloon being inflated to fix it in position against the wall of said vessel at said desired location, expanding in response to said predetermined further amount of pressure in said balloon to release said cannula from said mouth, and there-after contracting toward said specific predetermined internal size to close said balloon mouth and thereby retain said inflated balloon fixed in position against said wall.

2. A miniaturized balloon catheter as in claim 1 wherein said resilient contracting member does not wrap about said means forming said mouth more than once.

3. A miniaturized balloon catheter as in claim 1 wherein said balloon is of an elastomeric silastic material.

4. A miniaturized balloon catheter assembly as in claim 1 wherein said cannula and said balloon are normally of approx-imately the same diameter and attachment of the inflatable portion of the cannula is achieved by expanding the means forming a mouth, and extending it over the adjacent end of the cannula.

5. A miniaturized balloon catheter as in claim 4 wherein said resilient contracting member is a C-shaped spring.

6. A miniaturized balloon catheter as in claim 5 wherein the inner diameter of said balloon is approximately 0.011 inches and its outer diameter is approximately 0.024 inches while said C-shaped spring has an inner diameter of approxi-mately 0.018 inches when it is in a non-expanded condition.

7. A miniaturized balloon catheter assembly adapted for use in diagnostic and therapeutic procedures in connection with small vessels comprising; a cannula having means at a proximal end for attachment to a source of pressurized fluid and having a small outer diameter for insertion into small vessels, an inflatable tubular balloon having a mouth portion and mounted at the distal end of the cannula in fluid communi-cation therewith, the cannula and balloon adapted to be carried by the fluid in the vessel to a desired location therein, whereupon introduction of an amount of pressurized fluid flow from the source of pressurized fluid will inflate the balloon to fix it in position, activation means responsive to a further amount of pressure to initiate a desired pro-cedure within the small vessel at the desired location, said balloon being detachably mounted at the distal end of said cannula and having a sealing means thereon so that when the cannula and balloon are positioned in the desired location in the human vessel the cannula can be detached from the balloon whereupon the sealing means will seal the mouth portion of the balloon, said sealing means including elastomeric self-sealing plug material positioned in the mouth of the inflatable balloon adjacent to the end of the cannula, a circumferential expandable band on the outer surface of the inflatable balloon in concentric position with respect to the plug material therein, said assembly further comprising a pin having a passageway therethrough and one end mounted at the distal end of the cannula with the passageway therein in communication with the passageway through the cannula and the other end of the pin positioned through a small opening in the self sealing plug material into fluid communication with the inflatable balloon on the side of the plug material distal from the cannula and when in that position expanding the circumfer-ential band, so that when sufficient pressurized fluid has passed through the cannula and pin into the inflatable balloon to inflate the balloon to the desired amount, further fluid will inflate the mouth portion thereby freeing the cannula and attached pin from the balloon for removal whereupon the elastomeric self-sealing plug material will close the open-ing in the plug material and the mouth portion of the balloon to retain the balloon in inflated condition.

8. A miniaturized balloon catheter assembly as in claim 7 wherein the distal end of the pin has a beveled configuration.

9. A miniaturized balloon catheter assembly as in claim 7 wherein said elastomeric self-sealing plug material cooperates with the circumferential band to close the open-ing in the plug material.

10, In a miniaturized balloon catheter assembly adapted for use in diagnostic and therapeutic procedures in connection with small vessels comprising; a cannula having means at a proximal end for attachment to a source of pressurized fluid and having a small outer diameter for insertion into small vessels, an inflatable tubular balloon having a mouth portion and mounted at the distal end of the cannula in fluid communi-cation therewith, the cannula and balloon adapted to be carried by the fluid in the vessel to a desired location therein, whereupon introduction of an amount or pressurized fluid flow from the source of pressurized fluid will inflate the balloon to fix it in position, activation means respons-ive to a further amount of pressure to initiate a desired procedure within the small vessel at the desired location, said balloon being detachably mounted at the distal end of said cannula;
the subassembly of a sealing means which, when the cannula and balloon are positioned at the desired location in the human vessel, seals the mouth portion of the balloon, said sealing means including elastomeric self-seallng plug material positioned in the mouth of the inflatable balloon adj-acent to the end of the cannula, an expandable circumferential band on the outer surface of the inflatable balloon in concentric position with respect to the plug material therein, said sub-assembly further comprising a pin having a passageway therethrough and one end mounted at the distal end of the cannula with the passageway therein in communication with the passageway through the cannula and the other end of the pin positioned through a small opening in the self-sealing plug material into fluid communication with the inflatable balloon on the side of the plug material distal from the cannula and when in that position expanding the cir-cumferential band, so that when the balloon is detached from the distal end of the cannula the pin is removed from the plug material, whereupon the elastomeric self-sealing plug material and the expand-able circumferential band will close the opening in the plug material and the mouth portion of the balloon to retain the balloon in inflated condition.

11. The subassembly of claim 10 wherein said expandable circumferential band comprises a single strand element which does not extend about said plug material a plurality of times.

12. A miniaturized balloon catheter assembly adapted for use in diagnostic and therapeutic procedures in connection with small vessels comprising; a cannula having means at a proximal end for attachment to a source of pressurized fluid and having a small outer diameter for insertion into small vessels, an inflatable tubular balloon having a mouth means constructed of self-sealing material for forming an opening into said balloon through which said balloon can be inflated, but which can be closed to maintain said balloon in an in-flated state, said balloon being mounted at the distal end of the cannula in fluid communication therewith, said cannula extending into the mouth means of said balloon so that said balloon can be inflated and deflated via said cannula, the cannula and balloon adapted to be carried by the fluid in the vessel to a desired location therein, whereupon introduction of an amount of pressurized fluid flow from the source of pressurized fluid will inflate the balloon to fix it in posi-tion and a further amount of pressure will initiate a desired procedure within the small vessel at the desired location, said balloon having a sealing means thereon so that when the cannula and balloon are positioned in the desired location in the human vessel the cannula can be detached from the balloon whereupon the sealing means will seal the mouth portion of the balloon, said sealing means including a circumferential expandable-band means on the outer surface of the mouth means of said inflatable balloon tending to hold the balloon mouth means onto said cannula, said expandable-band means compris-ing a single strand element which does not extend about said mouth means a plurality of times, said expandable-band means and said mouth means having the joint function of responding to a sufficient amount of pressurized fluid passing through the cannula into the inflatable balloon to inflate the balloon to a desired amount by detaching the cannula from the balloon for removal of the cannula from the balloon mouth means, and responding to a decreased pressure in said balloon after said cannula has been removed by closing the opening in said mouth means of the balloon to retain the balloon in an inflated condition.

13. A miniaturized balloon catheter assembly for use in small vessels comprising:

a cannula including an attaching means at one end thereof for attaching to a source of pressurized fluid and having a small outer diameter for insertion into small vessels;
an inflatable balloon mounted on the opposite end of the cannula and in fluid communication therewith, the cannula and balloon adapted to be carried by the fluid in a vessel to desired locations therein, whereupon attachment of the cannula fluid source of pressurized fluid and introduction of amounts of pressurized fluid flow inflate the balloon;
said balloon including an activation means responsive to further amounts of pressures to initiate a de-sired procedure within the small vessels, said activation means comprising a reinforced portion of said balloon having a passageway therethrough, said passageway normally being so small that it effectively does not allow the passage of fluid from said balloon through said passageway, but said reinforced portion allowing the opening of said passageway in response to a predetermined amount of pressure within said balloon to allow passage of said fluid from said balloon into said vessels, said reinforced portion of said balloon being thicker than the remainder of said balloon.

14. A miniaturized balloon catheter assembly as in claim 13 wherein said passageway has a round cross-section with a diameter of approximately 0.001 inch.

15. A miniaturized balloon catheter as in claim 13 wherein said reinforced portion of said balloon forms plug material which extends inwardly into the interior of said balloon.

16. A miniaturized balloon catheter as in claim 15 wherein said passageway has a round cross-section with a diameter of approximately 0.001 inch.

17. A miniaturized balloon catheter as in claim 13 wherein said balloon having said passageway is formed by a molding process.

18. A miniaturized balloon catheter as in claim 17, wherein said balloon is formed by the process of:
covering a mandril with liquified resilient material of which said balloon is to be constructed, said mandril having the general shape of said balloon but includ-ing a pin protruding therefrom at the desired position of said passageway to form said passageway;
hardening the liquified material on said mandril;
removing said hardened material from said man-dril, said hardened material forming said balloon having a passageway therethrough.

19. A miniaturized balloon catheter assembly as in claim 18 wherein said pin has a round cross-section with a diameter of approximately 0.001 inch.

20. A method of constructing a balloon catheter having a perfusion passageway therein comprising the steps of:
covering a mandril with liquified resilient material, of which said balloon is to be constructed, said mandril having the general shape of said balloon but includ-ing a pin protruding therefrom at the desired position of said passageway to form said passageway;
hardening the residue of said molten material on said mandril; and, removing said hardened material from said man-dril, said hardened material forming said balloon having a passageway therethrough.

21. A method of constructing a balloon catheter as in claim 20 wherein said mandril includes an indentation therein, and said pin protrudes from said mandril at said indentation.

22. A method of constructing a balloon catheter as in claim 21 wherein said pin has a round cross-section with a diameter of approximately 0.001 inch.

23. A method of constructing a balloon catheter as in claim 22 wherein said mandril is constructed of steel.

24. A method as in claim 20 wherein said pin has a round cross-section with a diameter of 0.001 inch.

25. A method of constructing a balloon catheter as in claim 20 wherein said mandril is constructed of steel.