CA1134705A

CA1134705A - Balloon catheter and technique for the manufacture thereof

Info

Publication number: CA1134705A
Application number: CA000345700A
Authority: CA
Inventors: John W. Boretos
Original assignee: US Department of Commerce
Current assignee: US Department of Commerce
Priority date: 1979-02-14
Filing date: 1980-02-14
Publication date: 1982-11-02
Also published as: WO1980001647A1; EP0023917A1; US4254774A; EP0023917A4; JPS56500200A

Abstract

BALLOON CATHETER AND TECHNIQUE FOR THE MANUFACTURE THEREOF
Abstract A single-lumen, one piece catheter approximately 0.04 inch in diameter with an integral balloon at its end hav-ing a wall thickness of 0.005 or less, sufficiently small to be retractible by suction into the catheter and to be extensible at a desired site by fluid pressure. The bal-loon may have a calibrated restricted leak aperture. The balloon portion of the catheter is made by heating a por-tion of the catheter tubing, stretching the tubing length-wise, and applying fluid pressure to the tubing. The app-aratus for forming the balloon includes a spring-loaded clamp to hold the tubing at one end, a capstan to hold the tubing at the other end, a heating coil wrapped around the tubing near the clamped end thereof and mount-ed with the clamp, and a mechanism for controlling the pressure and volume of the pressurizing gas entering the lumen of the tube in accordance with the retractile move-ment of the spring-loaded clamp.

Description

113~7~S

Description BALLOONCATHETER AND TECHNIQUE FOR THE MANUFACTURE THEREOF

Technical Field This invention relates to balloon catheters, and more particularly to a balloon catheter wherein the balloon is a continuous, non-interrupted integral part of the cathe-ter wall, free of seams or joints.

Background Art Balloon catheters are useful tools of the clinical radiologist and surgeon and find application in diagnosing and treating innumerable àilments throughout the body.
They have been used in virtually all passageways from blood vessels, urinary tracts, or the like, to nasal and throat openings. They function to block flow of blood,a~r, urine, etc., to scrape vessel walls for the removal of clots, to block the flow of escaping air, and for numerous other uses. Generally, these devices consist of plastic or rubber tubing to which a rubber sleeve is mechanically fastened to stimulate a balloon. These fastenings usually consist of several wraps of fiber to anchor the edges of the balloon, followed by an overcoat of rubber or plastic.
As the sizes become smaller and the tubing becomes softer, these balloons are more difficult to construct and suffer from a lack of strength and reliability. Consequently, they have not been availab]e for use in diagnosis and treatment in many situatior-s. Thus, there is a significant need for very small-diameter catheters which exhibit a high degree of flexibility and reliability and, because of their gossamcr nature, are capable of navigating the tortuous paths of small (less than 1 mm) lumen vessels leading to tumors, arteriovenous malformations, aneurysms, angiomas, an(l thc likc.
Existin~ balloon catheters have various serious shortcolnings mainly becausc the balloon is connected to `-` 113~705 the cathetic tubing wall by seams or joints which present difficult fabrication problems, which are subject to leak-age or rupture, and which interfere with the smooth move-ment of the catheter in its intended passage because the seams or joints are relatively bulky.
A preliminary search of the prior art reveals the following prior ~.S. patents of interest:
Koehn, 3,050,066 Dereniuk, 3,528,869 Vasquez et al, 3,833,004 Dyke, 4,003,382 Kerber, 4,029,10 Disclosure of Invention The device of the present invention overcomes the shortcomings of existing balloon catheters by providing the balloon as an integral part of the wall of the cathe-tic tubing, free of seams or joints that might be subject to leakage or rupture. Also, the device of the present invention is of a nature to allow a wide variety of mater-ials to be used for catheters, namely, it allows the useof any thermoplastic or thermosensitive material. This feature of versatility, according to the present invention opens up new applications for catheters, for instance, it allows the catheter to be specially treated for antithro-mbogenicity, antisepsis, or the like, by surface modifica-tion and other chemical treatments or alterations~ ~ccord-ing to the present invention balloon catheters can be made as small as several mils in diameter with precision and reliability. They can be either constructed with (1) a terminal balloon and no open lumen at its end, (2) a ter-minal balloon with a calibrated and controllable leak at its end, or (3) any number of combination of the above two types.
A balloon without a terminal lumen can be readily constructed using the technique of the present invention.
Temporary or permanent blocking of vessels of any size can be realized with these catheters. Temporary blocking, ,~_ . ... .. . . . .

7~S

for example, is especially useful for (a) clinical and electro-physio]ogical study of the collateral blood supply of a vascular system distal to an occluded vessel, (b) angiographic investigation of the collateral blood flow from systems ad~acent to that of the occluding vessel, (c) trials of the therapeutic effect of occluding a vessel functioning as a shunt or the afferent vessel of an arter-iovenous aneurysm, and (d) study of the effect of reducing or eliminating blood flow in a vessel.
The use of-a balloon with a calibrated leak,in accord-ance with the present invention, in very small (less than 1 mm diameter) vessels could provide for (a) selective angiography of a vessel located either distal or proximal to an occluded section of a vessel, (b) injection of fluid hardening polymers into an aneurysm, blocking a malforma-tion or isolating a tumor, (c) injection of radiopaque materials for tumor stainins for disclosure and (d) sun~ly-ing chemotherapeutic agents locally, as to a tumor. ~ ~al-ibrated l~ak can be built into the terminal end of the bal-loon cathetcr during fabrication, as will ~e presentlydescribed, prior to expanding the wall to form the balloon.
With this design, the balloon will inflate under predeter-mined pressure before "leak~ing" pressure or fluid. Vary-ing degrees of inflation can serve two functions: (1) to block the vessel and prevent retrograde flow, or (2) part-ially inflated, to act as a float to carry the catheter to otherwise inaccessible areas, utilizing the flow of blood around and against it to propel it alon~. The combination of its small size, gassamer nature, and reliably inflat-able balloon, provicled by the technique of the presentinvention, allows the catheter to traverse through small and windins passages leading to the brain, liver, pan-creas, spleen, kidneys, etc. Once the catheter has arri-ved at the intended site, additional pressure will allow whatever fluid or agellt which is to be delivered to "leak-out" of the lumen. The amount delivered is a function of the applied pressure, the size of the capillary, the - 113~7~1S

elapsed time, and the viscosity of the su~plied substance.
The catheter of the present invention relies on com-plete flexibility to perform its function, namely, of traversing 1 mm and smaller vessels while being free to flèx over small radii of less than one-half of the vessel diameter so that it can readily enter smaller branch vessels located at acute angles. For this reason, even the softest of catheter materials must possess extremely thin walls (i.e., less than 0.005 inch, and preferably 0.002 inch or less~ and I~O 5e~s or joints that might add stiffness and subsequent resistance to movement such as in the previously employed devices.
The catheter of the present invention has a one-piece construction which minimi~es the possibility of detach-ment or separation of portions thereof accidentally in acritical area of the body where harm may be incurred to the patient, such as in the area of the brain or lungs.
In these small sizes, bond lines, cement joints, or fast-eners employed with previously used catheter devices must be concomitantly small and weaker than on conventional size catheters. Furthermore, as the inner bore of cathe-ters becomes increasingly smaller, greater pressures must be exerted along the catheter to deliver a drug or medication through it. These higher pressures could also add to the risk of destruction or accidental rupture of catheters of the "assembly-type, whereas all of these problems are avoided by the simple one-piece construction of a catheter accordin~ to the present invention. Also, the device of the present invention is well suited for automation in its fahrication, without requiring compli-cated and expensive assembly equipment such as is re-quired in fabricating previously employed catheters.
Accordingly, a main object of the invention is to provide a balloon catheter which overcomes the deficienc-ies and shortcomin~s of the previously employed ballooncatheters.

1~3'~7V5 A further object of the~invelltion is to provide all improved balloon catheter which is of continuous, non-in-terrupted, one-piece construction, free of seams or joints.
A still further object of the invention is to provide an improved balloon catheter which has an integral balloon of very srnall wall thickness so that the ha]loon may be readily retracted into the associated catheter tube to facilitate the insertion and placement of the catheter, and so that the balloon may be readily inflated at its intended site.
A still further object of the invention is to provide an improved balloon catheter of continuous smooth, one-piece construction which has a balloon of very small wall thickness and which is easy and inexpensive to manufacture, which is reliable in operation, which is capable of vary-in~ degrees of inflation, and which can be efficiently used for naviqating the tortuous paths of relatively small-lumen vessels.
A still further object of the invention is to provide an improved technique and apparatus for fabricating bal-loon catheters allowing the use of a wide range of thermo-plastic or thermosensitive materials and requirinq rela~
tively simple and inexpensive fabrication equipment.
A sti]l further ob~ect of the invention is to provide an improved completely flexible balloon catheter which includes an inte~ral balloon of very smail wall thickness and which is provided with a calibrated leak orifice for enabling a substantial ranqe of functions, such as selec-tive an~ioqraphy of a vessel located either proximal ~r 3b distal to an occluded section of the vesscl, injection of desired material for blockin-l or isolatinq a turnor, injec-tion of radio~aque materials for tumor stainin~, or the like, supnlyinq chemotherapeutic aqents locally, or for other deslred r~urposes.
~ still further object of the ;nvention is to r~l-o-vide an improved balloon catheter which has a smooth unin-terrupted external contour and llas comr~]etc flcxibility for accomplishing its function namely, which is capable of transversing 1 mm and smaller vessels while being free to flex over small radii of less than one-half of the vessel diameter so that it can readily enter smaller branch ves-sels located at acute angles, the construction being such as to provide safety from accidental disintegration or separation into segments or pieces in critical areas of the body where harm may be incurred to a patient, such as in the area of the brain or lungs.
A still further object of the invention is to provide a novel and improved safe and reliable design for a bal-loon catheter which offers a greater choice than was previously available of materials from which the balloon catheter may be constructed, and which allows miniaturiza-tion to an extent heretofore unobtainable to occlude small vessels, and which allows passage of various liquids through the catheter under controlled conditions, the improved balloon catheter being readily fabricated from conventional materials, and wherein its,manufacture readily lends itself to large scale production methods.
According to the above objects, from a broad aspect, the present invention provides a device for passage into a body vessel or passageway of diameter lmm or smaller. The device comprises a unitary, integral and seamless balloon catheter of smooth uninterrupted contour having a single-lumen, flexible elongated catheter tube of diameter less than 40 mils integrally formed at one end with means to occlude the body vessel or passage'way and comprising an inflatable balloon of one piece construction. The catheter tube has a wall thickness of less than 5 mils and is suffi-ciently small relative to that of the tube to allow the balloon to be retracted by suction into the tube.

- 6a -Brief Description of Drawinqs Further objects and advantages of the invention will become apparent from the following description and claims, and from the accompanying drawings, wherein:
Figure 1 is an enlarged longitudinal cross-sectional view of the inflated balloon and adjacent tube portion of a balloon catheter constructed in accordance with the present invention.
Figure 2 is a longitudinal cross-sectional view similar to Figure 1 but showing a balloon catheter with a calibrated leak orifice according to the present invention.
Figure 3 is a longitudinal cross-sectional view of the structure of Figure 2, with the balloon element retracted into the catheter tube by suct~on~.
Figure 4 is a diagrammatic illustration of a typical 1~47(~5 apparatus for fabricating a balloon catheter employinq the fabrication technique of the present invention.
Figure 5 is an enlarged fra~mentarv vertical cross-sectional view showin~ the use of a contoured sleeve or mould employed for shaping a balloon, with the apparatus of Fi~ure 4.

Best Mode for Carrying Out the Invention Referring to the drawings, in Fi~ure 1, a catheter tube 11 is provided with an inteqral terminal balloon 12 in accordance with the present invention, shown in in-flated condition. The catheter tube may comprise any suit-able thermoplastic or thermosensitive material that can be made in the form of tubing, for example, polyurethanes, copolyester polymers, thermoplastic rubbers, silicon-poly-carbonate copolymers, polyethylene ethylvinyl-acetate, or combinations of these and/or others. Tubing of a ~redete~
mined wall thickness-to-diameter relationshi~ is selected so that when the balloon 12 is produced it results in a durable yet compliant membrane. This could ran~e from 1 mil to 20 mils wall thickness of the balloon, depen~in~
upon the overall diameter of the tubing and the size of the balloon desired. Also, the thickness of the balloon membrane can be regulate~. For example, a 40 mil dia-meter tube 11 with a 2 mil wall thickness could readily produce a 100 mil diameter balloon, or a ' mil wall tube could produce such a 100 mil diameter balloon, except that the balloon membrane would be thinner. Therefore one can tailor the characteristics of the balloon to suit a particular application. Len~th, diameter and shape of the balloon can also be requlated.
In a preferred embodiment, for examp]e, for a 4~ mil diameter tube 11, the wall thickness of the halloon is 5 mils or less. A balloon wall thickness of 2 mils has been employed with success.
As was previously mentione(3 herein,a ba~loon catheter such as is shown in Fi~ure 1 can be employed for t:cmpor-... .. . . . . ..

arily or permanently blocking vessels of any size. More specifically, as also mentioned above, temporary blockinq finds special utility in achievin~ the followin~ purposes:
(1~ the clinical and electrophysioloqical study of the collateral blood supply of a vascular system clistal to an occluded vessel, (2) the angiographic investi~ation of the collateral blood flow fro~ systems ad~acent to that of an occluded vessel, (3) trails of the therapeutic effect of occluding a vessel functioninq as a shunt, or the afferent vessel of an arteriovenous aneurysm, and (4) the study of effects accruing from the reduction or eli-mination of blood flow in a vessel.
It will be seen from Fiqure 1 that the balloon 12 is an integral part of the wall of the cathetic tubin~ and is free of seams or joints that miqht be subject to leak-age or rupture.
Figure 2 illustrates a balloon catheter similar to Figure 1 but with a calibrated leak nozzle 13 formed as a terminal lumen for the balloon, desi~nated at 12'.
The thin-walled balloon 12 or 12' may be retracted into the catheter tubing 11, as shown in Figure 3, by applying light suction to the tube, usin~ a syrinqe or other suitable suction means connected to the distal end of the catheter tubinq 11, whereupon the balloon immeclia-tely and completely retracts. This results in a "dis-appearinq" balloon with a strai~ht smooth-walled catheter.
This can be maved along unobstructedly until it reaches a point further within a vascular network, for example, where it then becomes advantageous to cleploy the balloon (by applying positive fluid pressure to the catheter) and allow the flow of blood to take over and push aqainst the balloon for forward movement (~ e., Propulsion). Once the catheter has per~ormecl its function (as ~reviously des-cribed) the balloon is readily retracted into the lumen proper of the tube 11 by applyinq sliqht suction to the exterior distal end of the catheter tube. Even though thc small leak nozzle (of the modification of Ei~ure 2)exists 11;~47~5 _9_ at the balloon end, it does not interfere with the retrac--tion, and the balloon readily collapses. The invaqinated balloon is then out of the way and allows for smooth with-drawal of the catheter.
To form the balloon, the catheter tubing is heated locally, i.e., in the area where the balloon is desired, until the tubing is soft and/or semi-molten. The exact temperature of the plastic an~ the amount of heat requir-ed to be applied will vary, depending upon the softening temperature of the material being used, but will usually be within the 100-250 C range. ~t this staqe the tubing 11 is stretched lengthwise, causing the heated portion to greatly narrow to form a constriction. ~ny size restric-tion can be obtained by regulating the amount of heat applied, the speed of application, the time, and the length of pulling. Openin~s of ca~illary size (or total closure) may be achieved. ~xcess tubing is cut off at the constriction upon completion of the pulling step, and/or coincident with the cutting the heat is removed and the balloon 12 or 12' is formed by applyin~ a predetermined amount of gas pressure to the inner lumen of the tubinq.
This pressure causes a circumferential expansion of the area which has been heated selectively. r~ost thermoplas-tic or thermosensitive materials will lose their heat in a matter of seconds and will "set" permanently into this inflated configuration. More rapid cooling can be pro-vided by passing air, mist or water over the previously heated surfaces. The size and shape of a ~lain spherical balloon is regulated by the amount of heat a~plied, the length of the area that receives the heat, and the press-ure and/or volume of the gas applied. Unusual sizes and shapes can be obtained, if desired, by ~roviding an inte nally contoured sleeve 20, defining the desired size and shape, of glass, metal or similar heat dissipatin~ sub-stance around the balloon to serve as a mou]d, as shownin Figure 5.
The halloon 12, without the tcrminal lumen elcmcnt . : . ~. . .

-` 11;34'705 13, is made in the same fashion as the balloon 12', e~cept that the heating time and temperature to form the ca~
ary are extended to a point where a permanent welding or ~usion of the end of the balloon-defining thinned wall area occurs, closing off said end.
Figure 4 diagrammatically illustrates a tvpical a~p-aratus for performing the above-described method. The tub-ing 11 is held in the apparatus by a sPring-loaded clamo 14 at one end and is supportingly wound on a ca~stan spool or pulley 15 at the other end. The capstan spool or pulley 15 serves to immobilize the tubing 11 without undue strain on collapse of the tubing lumen. A heating coil 16,inc1ud-ing resistance wire, such as nichrome wire, surrounds the tubing 11 near its clamped end. A current requlating device of conventional desiqn, shown at 17, and a timer 18 control the amount of energy imparted to the coil 16.
In response to localized heating of the tubing by the coil 16, the spring-loaded clamp 14 elongates the tubing local-ly to narrow its lumen, and at the same time the heated coil radiates heat to the area 19 above the narrowed lumen portion which wi]l subsequently become the balloon.
The clamp 14 and coil 16 are mounted together and move as one assembly.
The clamp 14 is suitably couplecl to a conventional pressure control mechanism 21 connected to the tubing 11 at the far end thereof, allowinq pressure-controlled gas to enter the lumen of the tubing. The conventional press-ure control mechanism 21 can he of a type comprising a solenoid-actuated drive for a syrinqe or other piston-actuated device. Gas Pressure and volume may be furthercontrolled by a conventional regulator 22 having a ~ress-ure gau~e23. The spring loading of the clam~ 14 may be provided by a suitable spring 24 resiliently connecting clamp 14 to an adjacent stationary anchorinc~ member,shown at 25.
While certain specific embodiments of improved bal-loon catheters and a method alcl ap~aratus for ~orming same have been disclosed in the foregoing description, it will be understood that various modifications within the scope of the invention may occur to those skilled in the art. Therefore, it is intended that adaptations and modi-fications should and are intended to be com~rehended with-ing the meaning and range of equivalents of the disclosed embodiments.

Claims

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

1. A device for passage into a body vessel or passage-way of diameter 1 mm or smaller comprising a unitary, integral and seamless balloon catheter of smooth uninterrupted contour having a single-lumen, flexible elongated catheter tube of diameter less than 40 mils integrally formed at one end with means to occlude the body vessel or passageway and comprising an inflatable balloon of one piece construction with said catheter tube having a wall thickness of less than 5 mils and sufficiently small relative to that of said tube to allow said balloon to be retracted by suction into said tube.

2. The balloon catheter of claim 1, and wherein said one-piece tube and balloon comprises thermoplastic material.

3. The balloon catheter of claim 2, and wherein said balloon has a wall thickness of approximately 0.002 inch.

4. The balloon catheter of claim 1, and wherein said balloon is provided with means for passage therefrom of a fluid into the body vessel or passageway, said means compris-ing a restricted leak aperture at the leading end of the balloon.

5. The balloon catheter of claim 4, and wherein said restricted leak aperture is in the form of a nozzle element unitary with the end of the balloon.

6. A balloon catheter of claim 5, said balloon having a wall thickness of approximately 2 mils.