LOW PROFILE BALLOON CATHETER AND METHOD

Abstract: This invention is a low profile catheter (21) comprising a flexible elongate tubular member (22) having proximal and distal extremities (23, 24), and having a guide wire lumen (26), and at least one balloon inflation lumen (27) extending from the proximal extremity to the distal extremity (24), said at least one balloon inflation lumen being offset eccentrically with respect to said guide wire lumen (26) having at least one inflatable balloon (31) formed thereon and having an interior in communication with said at least one balloon inflation lumen (27); said guide wire lumen (26) extending through said at least one inflatable balloon (30) and being offset eccentrically with respect to said at least one inflatable balloon (31).

Description: LOW PROFILE BALLOON CATHETER AND METHOD This invention relates to a low profile balloon catheter and method and more particularly to a balloon catheter and method which utilizes a unitary construction. Balloon catheters have heretofore provided, it has been conventional to provide such balloon catheters with balloons which are concentric with the shaft of the catheter so that the balloon inflates uniformly about the axis of the shaft of the catheter to a diameter which is normally substantially greater than the diameter shaft of the catheter. When the balloon is deflated, it typically has a circumference which is usually greater than the circumference of the shaft so that there is an excess of a balloon material which tends to fold up in various manners about the circumference of the shaft. This provides an overall circumference which is substantially greater than the circumference of the shaft making it difficult to maintain a low profile to make it difficult to negotiate the distal extremity of the balloon catheter through small vessels and into small stenoses. There iε therefore need for new and improved balloon catheter and a method which makes it possible to overcome these disadvantages. In general, it is an object of the present invention to provide a balloon catheter and method which makes it possible to achieve a very low profile for the balloon which is essentially the same as that of the shaft. Another object of the invention is to provide a balloon catheter and method of the above character in which single and multiple balloons can be provided. Another object of the invention is to provide a catheter and method of the above character in which the multiple balloons can be eccentric. Another object of the invention is to provide a balloon catheter and method of the above character in which the guide wire lumen is provided on one side of the shaft. Another object of the invention is to provide a balloon catheter and method of the above character in which the balloons are eccentrically disposed on the distal extremity of the catheter shaft. Another object of the invention is to provide a balloon catheter and method of the above character in which the balloons are eccentrically inflated with respect to the catheter shaft and with respect to the other balloons. Another object of the invention is to provide a balloon catheter and method in which the multiple balloons can be inflated eccentrically in staggered positions. Another object of the invention is to provide a balloon catheter and method of the above character in which the balloons can be inflated in offset eccentric positions. Another object of the invention is to provide a balloon catheter and method of the above character in which rapid exchange capabilities are provided. Additional objects and features of the invention will appear from the following description in which the preferred embodiments are set forth in detail in conjunction with the accompanying drawing. Figure 1 is a side elevational view of a balloon catheter incorporating the present invention. Figure 2 is an enlarged view partially in section of the distal extremity of the balloon catheter shown in Figure 1. Figure 3 is a cross-sectional view taken along the line 3-3 of Figure 2. Figure 4 is a cross-sectional view taken along the line 4-4 of Figure 2. Figure A is a view similar to Figure 4 but showing the deflated balloon profile. Figure 5 is an enlarged view of the distal extremity of a catheter incorporating the present invention in which a single balloon has been provided. Figure 6 is a cross-sectional view taken along the line 6-6 of Figure 5. Figure 7 is a cross-sectional view taken along the line 7-7 of Figure 5. Dotted lines show the deflated balloon profile. Figure 8 is an enlarged side elevational view of the distal extremity of a balloon catheter incorporating the present invention in which the balloons are staggered. Figure 9 is a cross-sectional view taken along the line 9-9 of Figure 8. Figure 10 is a cross-sectional view taken along the line 10-10 of Figure 8. Figure 11 is a cross-sectional view taken along the line 11-11 of Figure 8. Figure 12 is an enlarged side elevational view of the distal extremity of another embodiment of the balloon catheter incorporating the present invention in which the balloons are offset on opposite sides. Figure 13 iε a cross-sectional view taken along the line 13-13 of Figure 12. Figure 14 is a cross-sectional view taken along the line 14-14 of Figure 12. Figure 15 is a cross-sectional view taken along the line 15-15 of Figure 12 and showing in dotted lines the deflated profile of the distal balloon. In general, the low profile balloon catheter of the present invention comprises a flexible elongate tubular member which has proximal and distal extremities and has a guide wire lumen and at least one balloon inflation lumen extending from the proximal extremity to the distal extremity with said at least one balloon inflation lumen being offset eccentrically with respect to the guide wire lumen. The distal extremity of the flexible elongate tubular member has at least one inflatable balloon formed therein and having an interior in communication with the at least one balloon inflation lumen. The guide wire lumen extends through the balloon and is offset eccentrically with respect to the balloon. More particular as shown in Figures 1 through 4 of the drawings, the low profile balloon catheter 21 consists of a flexible elongate tubular member 22 having proximal and distal extremities 23 and 24 and having a guide wire lumen 26 extending from the proximal extremity 23 to the distal extremity 24. It has at least one balloon inflation lumen and as shown in Figures 1-4, two balloon inflation lumens 27 and 28 which extend from the proximal extremity 23 to the distal extremity 24. The flexible elongate tubular member 22 is formed of a suitable thermoplastic material well known to those skilled in the art as for example high density polyethylene. The material should be one which can withstand high pressure as for example 15 atmospheres at a minimum. At least one balloon and as shown in Figures 1-4, two balloons 31 and 32 are provided on the distal extremity 24 of the flexible elongate tubular member 22. Since the balloons 31 and 32 are typically formed of a non-elastomeric material, it is desirable that the balloonε be formed of the same material as the flexible elongate tubular member 22 so that they can be formed therefrom and made integral therewith. It should however be appreciated in connection with the invention that thermoplastic elastomers can be utilized when elastomeric balloons are desired. The plastic utilized in accordance with the present invention can be extruded in a conventional manner to provide the flexible elongate tubular member 22 with the guide wire lumen 26 and the balloon inflation lumens 27 and 28 therein. After the flexible elongate tubular member 22 has been extruded, the distal extremity can be thinned down by the application of heat and by stretching the distal extremity to aide in keeping a low balloon profile in accordance with the present invention. Thereafter the balloons 31 and 32 are formed therein. This can be accomplished by placing a mandrel in the guide wire lumen 26 to maintain the desired size for a guide wire as for example one which can accept a 0.014" guide wire and such as an inside diameter of 0.016". With the mandrel therein, the distal extremity of the flexible elongate tubular member 22 can be heated and tension applied to the distal extremity. The distal extremity of the flexible elongate tubular member 22 can be closed off to seal the balloon inflation lumens 27 and 28. As can be seen in Figures 3 and 4, the balloon inflation lumens 27 and 28 are offset to one side of the flexible elongate tubular member 22 or in other words are offset from the center axis of the flexible elongate tubular member 22. The distal extremity of the flexible elongate tubular member 22 in which the balloon or balloons is to be formed is placed in a mold of a suitable type as for example a glass mold (not shown) of a diameter and length suitable for the first or inner balloon 31 so that the balloon will be formed eccentrically with respect to the guide wire lumen 26. As soon as the mold is in place and the plastic has been heated to the desired temperature and placed under tension, a suitable fluid or air is introduced into the balloon inflation lumen 27 to supply air under pressure into the portion of the flexible elongate tubular member 22 within the mold to cause the plastic material to expand outwardly and thin out in an eccentric manner to form the first balloon 31 and carrying with it the plastic which is to form the second balloon 32. After the appropriate size balloon 31 has been formed in the mold, the air pressure within the balloon 31 is removed. Balloon 31 is taken out of the mold and permitted to cool down to room temperature. This cooling can be effected by supplying cooling air to the distal extremity 24. After the balloon 31 has been cooled, the distal extremity is then heated and placed under tension and placed in another mold of the same type as hereinbefore described which is sized for formation of the second balloon 32. Air pressure is then supplied to the balloon inflation lumen 28 to cause the formation of the second balloon by causing the plastic forming the second balloon inflation lumen 22 to expand eccentrically and to thin out to form the larger size balloon 32. After the balloon 32 has been formed in the mold, the air presεure can be released and the mold permitted to cool permitting collapse of the balloon 32 in the manner shown in Figure 4 so that the overall profile for the distal extremity carrying the balloons 31 and 32 is less than or substantially of the same circumference and diameter as the proximal extremity of the flexible elongate tubular member 22 and forming the shaft for the catheter 21. The inflated balloons 31 and 32 when expanded have an egg-shaped configuration in cross section as shown in Figure 4. By this procedure, the balloons can be formed with a wall thickneεs which is quite thin as for example from 0.0002" to 0.0010" and preferably a thickness of approximately 0.005" to 0.006" to form balloons of various desired diameters as can be seen from Figure 4, the wall thickness of the balloons decrease in a direction away from the guide wire lumen 26. Thus by way of example, the balloons can have an exterior diameter of 1.5 millimeters up to 8.0 millimeters. Balloon 31 can have a diameter 2.5 millimeters and the balloon 32 a diameter of 3.5 millimeters. As shown in Figure 4, the balloons 31 and 32 because of their thin walls collapse into a crescent-shape configuration as shown. By way of example, the catheter 21 can be of a suitable size as for example 3.0 French having an outside diameter of 0.039" with the guide wire lumen 21 being formed of a size so that it can accommodate a guide wire of 0.014" aε hereinbefore described. The distal extremity 24 with the balloons 31 and 32 thereon should have sufficient column strength to provide the necesεary pushability for the balloon catheter and particularly because of the presence of the guide wire lumen 26 extending therethrough. However, in the event additional column strength to provide greater pushability is desired, a an elongate stiffener element such as wire 36 can then be placed in the outer crescent shaped portion of the distal extremity 24 in which the balloons 31 and 32 are formed as shown in Figure 3 and embedded in the outer surface thereof. The braid thus provides additional column strength and pushability as well as improved torquability. It also should be appreciated that a similar braid 36 can be provided along the entire length of the flexible elongate tubular member 22 to provide additional torquability and pushability for the shaft of the catheter 21. A balloon inflation manifold 41 is mounted on the proximal extremity 23 of the flexible elongate tubular member 22 and is formed of a suitable material such as plastic. First and second Luer fittings 42 and 43 are provided on opposite sides of the manifold 41, the first Luer fitting 42 being in communication with the first balloon inflation lumen 27 for the balloon 31 and the Luer fitting 43 being in communication with the second balloon inflation lumen 28 for the second balloon 32. The manifold 41 is also provided with a third Luer fitting 44 which is in axial alignment with the axial axis of the flexible elongate tubular member 22 and is in communication with the guide wire lumen 26. A male Luer fitting 46 is coupled to a female Luer fitting 47 of a conventional type and is provided with a side port 48 which is connected to flexible tubing 49. The flexible tubing 49 is connected to another Luer fitting 51 which iε closed off by a removable cap 52. The tubing 49 is in communication with the guide wire lumen 26 so that a suitable liquid as for example a saline solution or a heparin solution can be introduced along with a guide wire 56 extending into and through the guide wire lumen 26. A conventional hemostasis valve 61 is mounted on the Luer fitting 47 and has a port (not shown) through which the guide wire 56 extends. The hemostasis valve 61 includes a sealing member (not shown) which can be presεed againεt the guide wire 56 to prevent the leaking of blood out around the guide wire 56 when the balloon catheter iε placed in a veεsel in a human body. To aide in locating and positioning of the balloons 31 and 32 in medical procedures hereinafter described, it is desirable to provide radiopaque markerε aε for example radiopaque markerε 66 and 67 formed on oppoεite endε of the balloons 31 and 32. As is well known to those skilled in the art, the radiopaque markers 66 and 67 can be formed by embedding radiopaque particles such aε barium εalt in convenient bands to form the radiopaque markers 66 and 67. Alternatively, metallic bands can encircle the flexible elongate tubular member and can be formed of a suitable radiopaque material such as platinum or a platinum tungsten alloy or gold. Operation and use of the low profile balloon catheter 21 may now be briefly described aε follows. Let it be assumed that it is desired to utilize the catheter 21 in a conventional angioplasty procedure in which there is a need to enlarge the flow paεεageway through stenosis in a vessel in the heart wall of the patient. Typically in such a procedure, a guiding catheter would be introduced through the femoral artery of the patient into close proximity to the deεired location in the patient. Thereafter, a guide wire 56 is introduced into the guiding catheter and advanced through the stenoεiε in a conventional manner. After the guide wire 56 haε been positioned, the low profile dilatation catheter 21 can be threaded over the guide wire and advanced through the guiding catheter and into and through the stenosiε so that the balloons 31 and 32 are in regiεtration with the εtenoεiε. Alternatively, the guide wire can be placed in the balloon catheter 21 prior to inεertion of the guide wire into the vessel. When that is the case, the guide wire 56 and the balloon catheter 21 can be progressively advanced into the guiding catheter and into the stenosis. As soon as the balloons 31 and 32 are in place, the first balloon 31, i.e. the smaller balloon can be inflated by connecting an inflation device to the lower fitting 42 to inflate the balloon 31. The balloon 31 will be inflated into an egg-shaped profile off to one side of the guide wire lumen 26 to cause compression of the plaque forming the stenoεiε to create a larger size flow passage through the stenosis. While the smaller balloon 31 is being inflated, the larger balloon 32 iε carried thereby in a deflated condition and moved into engagement with the plaque forming the stenosiε to form a larger flow passage extending through the stenosis. The smaller balloon 31 can be inflated and deflated several times as desired by the physician. After the inflation and deflation of the smaller balloon 31 for several period of times, it may be deεired to provide a εtill larger flow paεsage. This can be readily accomplished without replacement of the balloon catheter 21 by merely supplying a balloon inflation medium to the second balloon inflation lumen 28 by connecting an inflation device to the Luer fitting 43 and causing expansion to a larger size as represented by the dotted line in Figure 4 to still further compress the plaque and to form a still larger flow pasεage through the stenosiε. During the time that the second balloon 32 is being inflated, the first balloon 31 can remain inflated or can remain deflated. The positioning of the balloons 31 and 32 in the stenosis in the catheter can be readily observed through use of the radiopaque marker 66 and 67. After the desired εize flow passage through the stenosis has been achieved, the balloons 31 and 32 can be deflated as shown in Figure 4A and the balloon catheter 21 removed after which the guiding catheter can be removed and the site into the femoral artery sutured. From the foregoing, it can be seen that there has been provided a low profile balloon catheter 21 in which the collapsed balloons collapse into crescent-shaped forms which do not have a cross-sectional area which is substantially greater than the crosε-sectional area of the catheter itself. For this reason and by use of this type of construction, it is possible to provide low profile balloon catheter 21 which can negotiate small vessels and pasε through very εmall flow openings in stenoses in such vesselε. Since the low profile balloon catheter 21 can be formed of a εingle unitary piece of material, it iε poεsible to manufacture εuch catheters relatively inexpensively. Even if the desired pushability and torquability is desired for such catheters, this increased pushability and torquability can be readily incorporated into the catheterε merely by incorporating a braid in the appropriate locations along the length of the catheter. Another embodiment of a low profile balloon catheter incorporating the present invention iε the catheter 71 shown in Figure 5, 6 and 7 and consists of a flexible elongate member 72 which only the distal extremity 73 is shown by having a guide wire lumen 76 offset to one side of the same and having a single balloon inflation lumen 77 eccentrically dispoεed with respect to the guide wire lumen 76. A balloon 81 is formed in the diεtal extremity in the same manner as which the balloon 31 and 32 are formed to provide a generally egg-shaped configuration as shown in Figure 7 when inflated and providing a crescent-shaped configuration when deflated as also shown in dotted lines in Figure 7. The interior of the balloon 81 is in communication with the balloon inflation lumen 77. Radiopaque markers 83 and 84 are provided on opposite ends of the balloon. Still another embodiment of a low profile balloon catheter incorporating the present invention iε εhown in Figureε 8 through 11 in which a low profile balloon catheter 91 is shown consisting of a flexible elongate tubular member 92 having a distal extremity 93 which is provided with a guide wire lumen 94 on one side and first and second balloon inflation lumens 96 and 97. First and second balloons 101 and 102 are formed on the diεtal extremity 93 and aε shown are staggered or in other words are offset in longitudinally spaced-apart positions axially of the flexible elongate tubular member 92. As shown, the balloon 101 can be a smaller balloon whereas the balloon 102 can be a larger balloon. These balloons 101 and 102 can be formed by the same molding techniques hereinbefore described. Both of the balloons are offset eccentrically in the same direction from the guide wire lumen 94 and are in communication respectively with the balloon inflation lumen 96 and the balloon inflation lumen 97. Radiopaque markers 106 and 107; 108 and 109 of the type hereinbefore described are provided one at each end of the balloons 102 and 101 reεpectively. Operation and uεe of the low profile balloon catheter 91 is very similar to that hereinbefore described. The balloons 101 and 102 have generally an egg-shaped configuration or oval-shaped configuration as shown in Figureε 10 and 11 when inflated. Typically in uεe, the smaller balloon 101 would be advanced into the stenosis and inflated and deflated to increase the size of the flow pasεageway through the stenosiε. If a εtill larger flow paεεageway iε deεired in the εtenoεiε, the εmaller balloon 101 can be deflated and the catheter 91 moved diεtally to move the balloon 102 into regiεtration with the εtenosis after which it can be inflated and deflated to increase the size of the flow passageway through the stenosis. Thereafter, the balloons 101 and 102 can be deflated and the catheter 91 removed in the manner similar to that hereinbefore described. Another embodiment of a low profile balloon catheter incorporating the preεent invention is shown in Figures 12-14 SUBSTTTUTESHEET(RULE26) in the form of a low profile balloon catheter 111 consisting of a flexible elongate tubular member 112 which has a distal extremity 113 having a guide wire lumen 114 and first and second balloon inflation lumens 116 and 117 therein. As shown in Figure 12, the guide wire lumen is generally centrally disposed with the balloon inflation lumens 116 and 117 being offset eccentrically with respect to and on opposite sideε of the guide wire lumen 114. Firεt and second balloons 121 and 122 are formed in the diεtal extremity with the balloons being staggered as shown in Figure 8 but being offset in opposite directions from that shown in Figure 8. However, if desired, the two balloons 121 and 122 can be generally aligned as shown in dotted lines in Figure 12 so that the balloon 121 is offset in the opposite direction from the balloon 122 if that arrangement is deεired. The balloons 121 and 122 are formed in the same manner as hereinbefore described and when inflated have generally egg-shaped configurations as shown in Figures 13 and 14 and when deflated generally have crescent-εhaped configurationε. Radiopaque markerε 124, 126, 127 and 125 can be provided on the distal extremity 113, one at each end of the balloons 121 and 122. Operation and use of the low profile dilatation catheter 111 as shown in Figures 12-14 is very similar to that hereinbefore described. The balloons 121 and 122 can be advanced εequentially into the stenosis and inflated and deflated. If the balloons 121 and 122 are offset with respect to each other, the εmall balloon 121 can be inflated firεt followed by the second balloon 122 and thereafter by inflation of both balloons 121 and 122 simultaneouεly to provide a combined profile of a larger diameter. For example each of the balloonε 121 and 122 each having a diameter of 2 mm can provide a combined profile of approximately 4 mm. After the deεired enlargement of the flow passageway through the stenosis has been accomplished, the balloons 121 and 122 can be deflated and the catheter 111 removed in the manner hereinbefore described for the other catheters. From the foregoing, it can be seen that there has been provided a low profile balloon catheter that makes it posεible to achieve very low profileε. One or more balloons can be provided on the same catheter making it possible to readily achieve different balloon sizes permitting desired enlargements of flow passage ways through εtenoses without removal of the guide wire. The balloons, since they can be constructed of the εame material of which the catheter itself iε formed, can be formed of a single material greatly aiding the manufacture of balloon catheters at low cost. The construction also lends itself to rapid exchange catheters in which the guide wire can be brought out through an opening (not shown) just proximal of the most proximal balloon provided on the balloon catheter. It should be appreciated that although single and double balloonε have been provided on the low profile catheterε of the preεent invention additional balloonε can be provided on the diεtal extremity of the catheter with the correεponding number of balloon inflation lumenε being carried by the catheter.

Claims: CLAIMS 1. A low profile catheter comprising a flexible elongate tubular member having proximal and distal extremities and having a guide wire lumen and at leaεt one balloon inflation lumen extending from the proximal extremity to the diεtal extremity, said at least one balloon inflation lumen being offset eccentrically with respect to said guide wire lumen, the distal extremity of said flexible elongate tubular member having at least one inflatable balloon formed thereon and having an interior in communication with said at least one balloon inflation lumen, said guide wire lumen extending through said at least one inflatable balloon and being offset eccentrically with respect to said at least one inflatable balloon. 2. A catheter as in Claim 1 wherein first and second inflatable balloons are provided on the distal extremity and wherein first and second balloon inflation lumens are provided in the flexible elongate tubular member in communication with the first and second inflatable balloons. 3. A catheter as in Claim 2 wherein one of said first and second inflatable balloons haε a size which is different from the size of the other of the first and second inflatable balloons. 4. A catheter as in Claim 3 wherein said first and second inflatable balloons are offset from each other longitudinally of the flexible elongate tubular member. 5. A catheter as in Claim 3 wherein said first and second inflatable balloons are mounted eccentrically in opposite directions from each other to provide a combined profile of larger inflated diameter. 6. A catheter as in Claim 3 wherein said first and second inflatable balloons are generally aligned longitudinally of the catheter. 7. A catheter as in Claim 1 together with means for inflating the balloon through the balloon inflation lumen. 8. A catheter as in Claim 1 wherein said at least one balloon when deflated has a crescent-shaped configuration. 9. A catheter as in Claim 2 wherein said firεt and εecond inflatable balloons are formed of the same material as the flexible elongate tubular member. 10. A catheter as in Claim 2 wherein said first and second inflatable balloons are formed of a non-elaεtomeric material. 11. A catheter as in Claim 2 wherein said first and second inflatable balloons are formed of a material different from the flexible elongate tubular member. 12. A catheter as in Claim 11 wherein said firεt and second inflatable balloonε are formed of an elastomeric material. 13. A catheter as in Claim 1 wherein said at leaεt one inflatable balloon when inflated haε an egg-shaped configuration when inflated and a crescent-shaped configuration when deflated. 14. A catheter as in Claim 13 wherein the at leaεt one inflatable balloon has a wall thickness which decreaseε in a direction away from the guide wire lumen. 15. A catheter as in Claim 8 further including a braid embedded within a portion of the balloon having a creεcent- shaped configuration. 16. A catheter as in Claim 15 further including a braid extending the length of the flexible elongate tubular member. 17. A method for providing a low profile balloon catheter comprising a flexible elongate tubular member having proximal and distal extremities and having a guide wire lumen and at least one balloon inflation lumen in which the guide wire lumen iε offset to one side of the flexible elongate tubular member and forming an inflatable balloon having an interior on the distal extremity disposed eccentrically of the guide wire lumen and having its interior in communication with the balloon inflation lumen, the balloon being formed during formation with a wall thickness with a wall thickness which decreases in a direction away from the guide wire lumen so that when the balloon is deflated, the balloon collapses into a crescent-shaped configuration about the guide wire lumen. 18. A method as in Claim 17 further comprising the step of forming additional balloon on the distal extremity of the flexible elongate tubular member eccentrically of the guide wire lumen. 19. A method as in Claim 18 further comprising the step of forming the additional balloon so that it is offset longitudinally with respect to the firεt named balloon. 20. A method aε in Claim 18 further comprising forming the additional balloon so that it is dispoεed eccentrically oppoεite the firεt named balloon to provide a combined profile of larger diameter. 21. A method as in Claim 17 further comprising forming the balloon of the same material as the flexible elongate tubular member. 22. A method as in Claim 17 further comprising forming the balloons of an elastomeric material.

Inventors: GANDHI DEEPAK R, HEGDE ANANT V, IMRAN MIR A, GANDHI, DEEPAK, R., HEGDE, ANANT, V., IMRAN, MIR, A.
Applicants: INTELLIWIRE INC, INTELLIWIRE, INC.
Application year: 1996
Main classification: A61M29
IPC codes: A61M25, A61M29