CA2106845A1

CA2106845A1 - Collapsible balloon catheters

Info

Publication number: CA2106845A1
Application number: CA002106845A
Authority: CA
Inventors: William J. Gahara
Original assignee: Individual
Current assignee: Individual
Priority date: 1991-04-26
Filing date: 1992-04-13
Publication date: 1992-10-27
Also published as: IE921283A1; EP0580699A1; US5195970A; JPH06506848A; WO1992019306A1

Abstract

2106845 9219306 PCTABS00017 A flexible plastic inflatable and collapsible medical dilatation balloon (10) and balloon catheter wherein the internal surface of the balloon has been formed with a longitudinal geometry that prevents a flat collapsed configuration of the balloon. The internal surface of the balloon is imparted with a small raised rib (11) configuration, which maintains a minimal contact with the internal surface of the balloon, so that the ribs remain in place along the length of the balloon. The geometry so formed on the internal surface of the balloon also increases the pressures the balloon would normally withstand when the balloon is inflated to dilate a vein or artery. The internal surface geometry can be manufactured by extrusion methods.

Description

W 2/l9~K 2 1 0 6 ~ ll 5 PCT/US92/02970 2Background of the Invention 3Field of the Invention 4This invention relates to ballo~ns and to balloon catheters which are useful in medical dilatation 6 procedures and is more particularly concerned with the 7 development of a collapsible dilatation balloon that can 8 withstand significant inflation pressures and upon 9 deflation avoids the problem of "wingingl`, that is the development of flat, lateral portions projecting laterally 11 out~rd beyond the rest of the catheter~
1~ Description of the Prior Art 13 Balloon catheters are finding increasing use in 14 medical procedures such as percutaneous transluminal angioplasty, percutaneous transluminal nephrostomy, 16 ureteral dilatation, biliary duct dilatation, percutaneous 17 transluminal renal angioplasty, and the like. Balloons 18 for use in these procedures have been prepared from a 19 variety of polymeric materials which are blood and tissue compatible. Among those materials that have been employed 21 include materials such as poly(vinylchloride), ~ ?olyethvlene and the like, homopolvme s o- copolymers of 23 olefins, polyeLhylene/vin~l a-e.ate co?olymers, 24 polvethylene terepthalate and ?olyurethanes.
~5 Catheter balloons must be qu_te st~ons to withstand 26 significant infla'ion pressures. Accordingly, they 27 sometimes tend to be somewhat stif-, since their wall 28 thickness must be sufficient to p-ovide the necessary ~9 strength. Thus, when deflated, such catheter balloons can 3n flatten in a Dhenomenon known as l'winging", in which the 31 flat, lateral portions of the deflated balloon proiect 3~ laterallv outward beyond the res~ of the catheter. This 33 is deemed to be undesirable by mar.y pra_ti'ioners because 34 o~ 2 concern that the flat wings mav damage, e.g. an 3$ a_terv wall, as the deflated balloon is removed from the 36 arterial svstem. Also, such -lat wings can interfere witn WO92/19~K -2- PCT/US92/02g 1 the manipulation of the catheter and its easy advancement

2 through the arterial system.

3 A recent attempt to solve the problem of winging has

4 been reported in U.S. Patent No. 4,941,811, which S describes a balloon catheter wherein the balloon defines 6 transition zones at the respective ends which are of a 7 rounded fluted shape. The flutes, typically from three to 8 eight, are described as generally longitudinally directed 9 at an angle to the balloon a~is, and typically extending at a mutually perpendicular radial angle to the axis, the 11 lateral anqle beino generally from 0 t~ about 45 degrees, 12 preferablv about 10 to 30 degrees. The radial angle in 13 the as-molded balloon is described as dependent on the 14 lenqth of the transition zone and the relative diameters of the balloor and the connected catheter portions, being 16 typically about 10 to ~5 degrees. These balloons are 17 Drepared by a blo~J molding operation, wherein the shape of 18 the balloon is governed by the inner shape of the molding 19 chamber of the blow mold. Accordingly, the outer surface of the ballo~ns, at the transition zones, contains an 21 indentation ~Yhich accounts for the grooves or flutes as ~2 defined therein. ~inallv, it is noted that the central ~3 por ions c~ the catheter are directed into a mode of colla2se by the f~utes which is generally similar to the ~S mode Oc collapse in the fluted transi~ion zones, wherein ~6 the projecting "~ings'` are then avoided alon~ the entire 27 len~th of the collapsed balloon catheter.
28 While the above balloon apparently prevents a flat-29 collapsed configuration of the balloon, it does not contem~late the advantages of the instant invention, which 31 has found that an extremely sma'l raised ribbed 3~ confi~uration of essentially any geometry on the inner 33 ~urface cr the balloon, wherein the ribs need only 34 maintai~ some minimal contact angle with the inner balloon wall, can com?letely ?reven~ a flat-collapsed 3~ confiquration of the balloon. Fu~thermore, the ribs as 2:~0~'15 )2/19~K PCT/US92/02970 l defined run parallel along the entire longitudinal length of the balloon and there is no need to specify a lateral 3 or radial angle of such ribs. Such a design also provides 4 for a much lower profile on any given catheter shaft that the balloon is employed. Moreover, the inner surface 6 configuration described above can be manufactured by 7 e~trusion methods.
8 In accordance with this invention, a balloon 9 configuration for a balloon catheter is provided, which eliminates the undesirable winging phenomena that is ll encountered when the catheter balloor. is in a deflated l2 condition. Also, the catheter balloon is stronger than 13 prior art catheter balloons with improved tensile 14 strength, while exhibiting a reduced wall thickness to imorove the flexibilitv of the balloon. Thus, with the 16 catheter balloon of this invention, balloon catheter 17 procedures can be performed more effectively, with less 18 concern about damage to the patient's veins or arteries by l9 the "winging" phenomena of the dellated catheter balloon, and with ease of catheter advancement through the veins or 21 artery system.
2~ According'~y, it is the obiec~ of this invention to 23 overcome the "wings" using a bal~oon àesign tha~
2~ collapse the balloon evenly around the catheter a full 360 degrees.
26 It is a further object of this invention to provide a 2? balloon design that is suitable for use with the variety 28 of polymeric materials that are used in dilatation balloon 29 catherization~
Yet a further object of this invention is to provide a 31 balloon design that will colla?se the balloon evenly 32 around the catheter a full 360 degree- while at the same 33 time bein~ capable of production via standard plastic melt 3~ ?rocessing technioues such as ex-rusior..
St" l a further ob~ect o' this invention is to provide 36 a rela_ivelv small, internal1 -ibbec, raised level, W092/19~K 2 1 ~ 6 Y ~ 5 PCT/US92/029 -1 triangular, rectangular, square, circular or semi-circular 2 parallel protrusion along the complete longitudinal 3 internal surfaces of the dilatation balloon which can then 4 be employed in a balloon catheter for use in a dilatation ~rocedure such as angio~lasty and the li~e, the internal 6 surface modified balloon catheters being capable of 7 withstanding higher pressures as compared to balloons 8 without internal surface modification, which also serves 9 to provide a lower profile balloon configuration.
These ob~ects, and other objects which will become 11 a~aren' from the descri~tion which follo~s, are achievec 12 bv the balloons and the balloon catheters of the inventior.
13 and bv the methods for their preparation. Thus, in its 14 broades aspect, the invention comprises balloons and balloon catheters for use in medical dilatation procedures 16 wherein the materials employed for the preparation of the 17 balloons can be altered during their processing and 18 preparation into an elastic balloon configuration that 19 collapses evenly around the surface of a dilatation catheter.
21 Summary of the Invention 22 The invention comprises a flexible plastic material in 23 an inflatable and collapsible medical dilatation balloor.
24 and balloon cathete_ wherein the internal surface o' the 2; ba'loon has been integrally formed with 2 longitudinal 26 geometrv that prevents a flat-collapsed configuration of 27 the balloon~ The internal surface o' the balloon is 28 imparted with a small inwardly projecting raised-ribbed 29 configuration, substantiall~ equally spaced about the circumferance of the balloon, the ribs also maintaining 31 some minimal contact with the internal surface of the 32 balloon so tnat they remain in place along the length of 33 the balloor.. The geometry so formed on the internal 34 surface Q' the balloon also ir.creases the pressure the 3S balloon ~il 7 normall~ withstand when the balloon is 36 inflated tc dilate - vein or arter~. The internal surface 21 06~S
W 2/19~6 PCT/US92/02970 l geometry can be manufactured during the extrusion of a 2 balloon tube.
3 Brief Description of the Drawings 4 FIG. l shows, in cross-section, an extruded tube wherein the ribs are formed along the length of the 6 balloon;
7 ~IG. 2 shows, in cross-section, another typical 8 balloon in accord~nce with the invention;
9 FIGS. 3A-3C sho~ in plan and cross-sectional views typical e~trusion mandrel used to manufacture a typical ll balloon in accordance with the invention.
l~ ~IG. 4 shows, in cross-sec-ior., a circular geometry of 13 the ribs on the internal surface of the collapsible l4 balloon;
~IG. 5 shows, in cross-section, a semi-circular l6 geometry of the ribs on the internal surface of the 17 collapsible balloon;
18 FIG. 6 shows, in cross-section, a rectangular geometry l9 of the ribs on the internal surface of the collapsible balloon;
21 FIG. 7 shows, in cross-section, a triangular geometry 22 of the ribs on the internal s~rface of the collapsible ~3 ba'loon;
24 FIG. 8 shows, in partial cross section, a balloon anc catheter in accordance with the invention;
26 Detailed Description of the Invention 27 The invention will now be described by reference to 28 the various specific embodiments which are shown in the 29 a~tached drawings. It is to be understood that these embodiments are shot~ for purposes of illustration only 31 and are not to be construed as limiting.
3' The principal novelty in the medical dilatation 33 bal1oons and balloon catheters Or the invention lies in 3~ their internal surface geometry which has been integrally 3~ formed wi'h a longitudinal configuration that prevents a 36 f7at-col1a?sed configura'ion of the balloon while at the WO92/19~K '''~ ~l?~ ~ ~ PCTtUS92/02~

1 same time providing a balloon that is able to withstand 2 higher dilatation pressures. In ad~ition, the medical 3 dilatation balloon catheters of the invention provide a 4 low profile on any given catheter shaft.
The balloons and balloon catheters of the invention 6 are prepared in a conventional manner using conventional 7 equipment and employing any of the conventional 8 elastomeric materials used in the fabri_ation of 9 dilatation balloon catheters, Accordingly, any of the polymeric materials such as poly(vinylchloride), styrenic 11 polymers such as "KRATON", polyacrylates, polyoelfins, 12 ~olyamides, polyesters, fluoro?olymers, silicones and the 13 like, conventionally employed in the art to prepare 14 dilatation balloon catheters, can be employed to fabricate the dilatation balloon catheters of the instant invention.
16 For example, in producing a typical dilatation balloon 17 10 of the kind shown overall in FIG~. 1 and 2, a tube 18 having a wall thickness of about 0.05 mm to about 0.5 mm 19 and an internal diameter of about 0.8 mm to about 10 mm is produced by extrusion of the aforesaid plastic materials 21 using conventional melt processinq equipment. The 2~ extruded balloon tube is formed by ?assing the tube ove-23 an approp-iate sized mandrel which first provides tne 24 balloon with such precision wall thickness. At tAe same 2~ time that the mandrel operates to form the balloon tube, 26 it can also be configured to cause the formation of the 27 desired inner surface geometry which is shown as ribs 11 28 in FIGS. 1 and 2. FIGS. 3A-3C illustrate an ex~rusion 29 assembly in plan in cross-section 1~ a typical extrusion mandrel which operates to form a ~lurality of radiallv 31 inwardlv ~ro~ecting ribs extendinc along the entlre length 32 of the extruded balloon tube. The mandrel is inserted 33 into the extrusion die. A ga? 13 is set between the die 34 and mandrel after insertion, this gap forming the ~all of the tube and also forms any design on the internal balloon 36 wall. It can be seen tha' the cesian 1~ is cu into the W~ 2/l9~K 1 PCT/US92/02970 1 land area of the mandrel.
2 After extrusion, one end of an extruded balloon tube 3 is inserted into a mold having an internal configuration 4 corresponding to the external configuration of the desired balloon~ The balloon tube is then pinched off at one end, 6 the mold is heated above the softenins temperature of the 7 flexible plastic material and a suitable gas such as 8 nitro~en is used to pressuri2e and inflate the softened 9 portion of the tube and force t~e walls thereof into contact with the walls of the balloon~
11 In a more particular embodiment em?loying a material 12 such as a polvurethane, the tube is hea~ec in the mold 13 described above to a softening tem?erature in the range o 14 about 60 decrees C to about 150 degrees C.
It has been found, in accordance wi'h the presen~
16 invention, that any geometry of the internal ribs will 17 serve to prevent a flat-collapsed configuration of the 18 balloon. Accordingly, ribs that are triangular (FIG. 4), 19 rectangular (FIG. 5), square, circular (FIG. 6) or semi-circular (FIG. 7), which lie parallel to one another along 21 the complete longitudinal lensth on the inner surface of 22 the balloon act t~ eliminate ~he "winqing" effect 23 encountered in balloonc which lack such ar interna' 24 surface modification~ While the size` and number of ribs can be increased for olher reasons as described belo~, it 26 has been found that at least three ribs are necessary to 27 avoid the "winging" phenomena, and in a more preferred 28 embodiment the balloons have at least four ribs.
29 Furthermore, the ribs may be extremely small, and in 3Q the case of a rectangular configuration, the ribs have the 31 preferred dimensions of 0.005 inches (0.127 mm) deep by 3~ 0.003 inchea (0.0762 mm! wide. In the case of a round 33 configuratio~, it has similarly been found that a 34 preferred diamete- of 0.0005 inches (0.0127 mm) is sufficient to prevent a flat-colla?sed configuration. In 36 the broadest e.~bodimen_, it has been found that as long as WO92/l9~K ~ 5 PCT/US92/02S-`

1 the ribs protrude about 0.0001 (0.0025~ mm) inches into 2 the balloon, "winging" can be substantially eliminated.
3 Furthermore, for any of the ribs now described, the 4 ribs need only make minimum contact with the inner surface of the balloon sufficient to keep the ribs in place in a 6 given medical dilatation procedure.
7 It has also been found that while the above dimensions 8 of the ribs serve to prevent a flat-collapsed 9 configuration of the balloon, the ribs also increase the pressures tha~ one can apply in a dilatation procedure, 11 again, relative to those balloons that do not contain such 12 ribs. Accordingly, an increase in the size of the ribs 13 will allow a further increase in the pressure that can be 14 employed in dilatation, while still maintaining complete resistance to the development of a flat-collapsed 16 configuration when a vacuum is a?plied.
17 The actual dimensions of the balloons with a modified 18 internal surface geometry will depend upon the particular 19 dilatation procedure for which the balloon and any attached catheter are to be employed. In general where 21 the balloon is to be used in angioplasty, the external 22 diameter of the balloon will be o~ the order of about 2 mm 23 to about 25 mm. The overall length o' the inflated 24 tortion will be of the order of abou_ 10 mm to about 150 mm. The walls of the ba'loon will have an average 26 thickness in the range of about 0.01 mm to about 0.2 mm 27 dependin~ in part on the pressures to which the balloon is 2~ to be inflated in actual use.
29 As will be obvious to one skilled in the art, the dilatation balloons of the invention can also be employed 31 to replace dilatation balloons in a~y of the many other 32 t~pes of balloon-catheter combinations, with or without 33 cuide wires, currently em?loyed in medical dilatation 3~ procedures. Referring to the drawings, FIG. 8 shows a balloon catheter, which defines a tubular catheter body 3~ 15, a proximal hub 16, and a guice wire 17 which extends 2196~
Wf 2/19~K PCT/US92/02970 _g_ 1 through the catheter, all being of generally conventional 2 design. Catheter body 15 defines an inflatable and 3 collapsible balloon 18 of the invention with internal ribs 4 19, shown to be, as is conventional, in a tubular section of relatively larger diameter than the rest of the 6 catheter body 15. Balloon 18 may be an integral part of 7 the rest of the catheter body 15, or it may be separately 8 manufactured, for example, by an extrusion process and 9 then attached to the remainder of the catheter body 15.
Bal~oon 18 mav be entirely inflated to expand its 11 diameter, and ~ay also be collapsed to a minimum diameter 12 while, b~ thi~ invention, the rormatio-. of a fla~ "winaec"
13 configuration may be avoided in the collapsed mode o_ the 14 balloon.
1~ The balloons of the inven.ion possess properties which 16 render them especially valuable in carrying out medical 17 dilatation procedures such as angioplasty and the like.
18 Thus, the walls of the balloon are sufficiently thin to 19 allow the balloon to deflate without a flat-collapsed cor.figuration, and to permit 2assage into and through the 21 artery, vein or like passageway involved in a medical 22 ?rocedure. However, the walls of the balioon are 23 Dossessei o' suficien~ fle~u-al strength sucr tha- -h-29 balloon ~-ill not e~pand beyonc the o-isinall~ moldec con'i~uration under ?ressures u? ~o at least about 100 psi 26 or significantlv higher deper.sina upon the ~all thickness 27 and/o- overall size of the balloon. Hence, there is no ~8 problem or uncontrolled ex?ansion or danger of bursting 29 under pressure conditio~s rou~inely involvec in angioplast~r an~ like procedures. Further, because the 31 b2lloonc can be intearally molded on catheters of the same 32 material as ~hat used for the balloon or, alternatively, 33 can be securel~ bonded ~ithou- difficulty to other 3' ~aterialc emplo~ed ir the formation of cathe.ers, there is 3- lit~le or no risk o' ru?~ure a~ the junc.ion o balloon 3~ ar.~ cathete- while the dilata~io-. procedure is Dein~
.

WO92/19~K ~ (yl~ 5 PCT/US92/02' -1 carried out. Accordingly, the balloons and balloon 2 catheters of the present invention represent a significant 3 advance in the art.
4 The above has been offered for illustrative purposes only, and is not intended to limit the scope of the 6 invention of this application, which is defined in the 7 claims below.

Claims

That which is claimed is:

1. An inflatable and collapsible balloon for use in a medical dilatation catheter wherein the internal surface of the balloon has been formed with at least three radially inwardly projecting ribs (11) which project directly into the balloon and extend along the complete longitudinal length of the inner balloon wall, the balloon and ribs being of unitary construction wherein said construction acts to prevent a flat-collapsed configuration of the balloon.

2. The balloon of claim 1 wherein the radially inwardly projecting ribs (11) are of a triangular, rectangular, square, circular or semi-circular geometry.

3. The balloon of claim 1 wherein the inwardly projecting ribs (11) are substantially equally spaced about the circumference of the collapsible balloon.

4. The balloon of claim 1 wherein the inwardly projecting ribs (11) are rectangular and are of the dimensions 0.0127 mm deep by 0.0762 mm wide.

5. The balloon of claim 1 wherein the inwardly projecting ribs project 0.00254 mm into the balloon.

6. The balloon of claim 1 wherein the balloon is formed from a plastic material suitable for thermoplastic melt processing.

7. The balloon of claim 6 wherein the balloon is prepared from materials selected from the group consisting of poly(vinylchloride), polyethylene, ethylene copolymers, styrenic polymers, polyethylene/vinyl acetate copolymer, polyethylene terepthalate, nylon elastomers, silicone elastomers, fluoropolymer elastomers, and polyurethanes.

8. The balloon of claim 1 for use in the dilatation catheter procedure of angioplasty.

9. A method for producing the balloon of claim 1 comprising:
a. extruding a flexible plastic material over a mandrel which provides a tubular shaped extrudate wherein the mandrel causes the internal surface of the balloon to be integrally formed with a plurality of radially inwardly projecting ribs; and b. allowing the extrudate to cool to a temperature to solidify; and c. placing the extrudate into a blow molding assembly wherein the tube is heated and expanded into the mold into a desired balloon shape with the balloon and ribs being of unitary construction.

10. A catheter having a catheter body, a portion of said body defining the inflatable and collapsible balloon of claim 1.