CA2207189A1

CA2207189A1 - Dilation catheter

Info

Publication number: CA2207189A1
Application number: CA002207189A
Authority: CA
Inventors: Jaroslav Janacek
Original assignee: Individual
Current assignee: Individual
Priority date: 1994-12-30
Filing date: 1995-12-29
Publication date: 1996-07-11
Also published as: EP0805702A4; EP0805702A1; US5667493A; ATE212868T1; US5882336A; DE69525375D1; WO1996020751A1; EP0805702B1; DE69525375T2

Abstract

This invention is a dilation catheter (10) for use in performing angioplasty procedures. The catheter includes a relatively long catheter shaft (20) which has two lumens (20-1, 20-2). A relatively short guidewire receiving tube (30) is thermally bonded to the distal end (24) of the shaft, with its lumen approximately aligned with one of the lumens of the catheter shaft, and a stiffening wire (22) positioned therein. A dilation balloon (40), preformed with a shape that enables it to be used in an offset configuration, is thermally bonded to the distal end (44) and proximal end (42) of the tube, with its lumen aligned with the remaining lumen of the catheter shaft. The balloon and tube together define channels for the perfusion of blood past the balloon, which channels remain open even when the balloon bears against the tube during the inflation thereof.

Description

W O 96120751 PCTAUS9~/16876 4 Dilation Catheter Backoround of the Tnvention 6 The present invention relates to dilation catheters, 7 and is dire~ted more particularly to a dilation catheter 8 which allows blood to flow t~ere~y while it is being used 9 to perform an angioplasty procedure.
The use of angioplas.y to treat patients having 11 stenoses, i.e., regions o constricted blood flow, in 12 coronary arteries has ~ecome a widely accepted 13 alternative to more invas ve treatments. With this 14 procedure the ~alloon o_ a dilation catheter is maneuvered into position ac-oss a stenoses, inflated to 16 increase the size of the blco~ flow passage therethrough, 17 and then deflated and wit:~-awn. In many cases this 18 procedure has been found to p-oduce a lasting increase in 19 the rate of blood flow throl-sh the region of the stenoses thereby eliminatins the need f_r coronary bypass surgery.
21 In many cas2s the ar.gio~lasty procedure must be 22 performed on a succession c_ stenoses having di~ferent k3 locations and sizes, necess-tating the use of dilation 24 catheters having different b~lloon sizes. In other cases it has been found that the proper treatment of a stenoses 26 re~uires the application thereto of a succession of 27 dilation balloons of prosressively increasing size.
28 Because the inser.ion of z dilation catheter into the 29 body of a patient and the subseouent maneuvering thereof unavoidably presents some risk OL injuring the walls of 31 the patient's blocd vessels, dilation catheters are used 32 in conjunction with a gul~ing catheter which rQm~ i nc 33 inside the patient throusrGut the procedure and which 34 serves to protect the ~locd vessels from a~rasion as successive dilation catheters are inserted and withdrawn.
36 Dilation catheters are ~lso used in conjunction with 37 a guidewire which, like th~ gui~ing catheter, remains 38 within the patient when the dilation catheter is removed CA 02207189 1997-0~-27 W O96/207~1 ' PCTrUS95/16876 1 and replaced. This guidewire not only serves as a track

2 or guide for the dilation catheter while it is inside of

3 the guiding catheter, it also facilitates the final

4 positioning of the balloon at a stenosis after the dilation catheter emerges from the end of the guiding 6 catheter. Dilation catheters which may be exchanged 7 without the removal and reinsertion of the guidewire are 8 said to have a "rapid exchange capability". Examples of g dilation catheters having such a rapid exchange capability are shown and described in U.S. Patent Nos.
11 4,762,129 (Bonzel) and 5,061,273 (Yock).
12 In most cases the full benefit of the angioplasty 13 procedure will not be realized if the dilation balloon is 14 deflated immediately after being inflated. This is because it takes time for the material making up the 16 stenoses to reconfigure itself and become consolidated 17 into a mass that will not readily return to its original 18 flow constricting shape. As a result, the balloon may 19 have to be maintained in its inflated state for many seconds. This can result in a serious risk to the 21 patient because, unless special provision is made for the 22 perfusion of blood thereby, an inflated dilation balloon 23 will stop the flow of blood through the vessel in which 24 it is located. Dilation catheters which make provision for the perfusion of blood are said to have a "perfusion 26 capability". Examples of dilation catheters having such 27 a perfusion capability are shown and described in U.S.
28 Patent Nos. 4,763,654 (Jang) ~nd 4,983,167 (Sahota).
29 The dilation balloons of dilation catheters are ordinarily of one of two types. A first of these types 31 includes balloons which are distributed more or less 32 symmetrically with respect to the associated guidewires.
33 Examples of dilation catheters which include balloons of 34 this type and which have a rapid exchange capability include the previously cited Bonzel and Yock patents.
3~ Examples of dilation catheters which include balloons of 37 this type, bUt whiCh do not have a rapid exchange 38 capability, are described in U.S Patent Nos. 4,323,071 W O96120751 PCT~US95/16876 1 (Simpson et.al.) and 4,1g5,637 (Gruntzig et.al.).
2 Dilation catheters having ~alloons of this type have the 3 advantage that they act on a stenosis uniformly in all 4 directions, but have the disadvantage that they are unable to present the stenosis with a surface that is 6 relatively stiff, i.e., unyielding. Such a sur~ace can 7 be beneficial in the case of stenoses that are relatively 8 hard and need to be, in effect, "crac3~ed" open.
9 A second of these types includes balloons which are lo offset to one side of the associated guidewire. Examples 11 of dilation catheters which include one or more balloons 12 of this type are described in U.S. Patent nos. 5,071,406 13 (Jang) and 5,304,132 ~Jang), neither catheter having 14 either a rapid exchange capability or a perfusion capa~ility. One advantage of dilation catheters having 16 balloons of this type is that they are able to present at 17 least part of a stenosis with a relatively stiff sur~ace.
18 Another advantage is that their lack of symmetry enables 19 them to be oriented for use in treating stenoses that are distributed unsymmetrically within a blood vessel.
21 In view of the foregoing it will be seen that, prior 22 to the present invention, there has not been available a 23 dilation catheter which has both a rapid exchange 24 capability and a perfusion capability, and yet which has all of the advantages of dilation catheters that include 26 offset balloons.

28 Summarv of the Invention 29 In accordance with the present invention there is provided an improved dilation catheter which utilizes an 31 offset dilation balloon and yet which has both a rapid 32 exchange capability and a perfusion capability.
33 Generally speaking, the present invention comprises 34 a dilation catheter including a catheter shaft, a guidewire receiving tube which has a length that is small 36 in relation to the len~th of the catheter shaft and which 37 is secured in proximity to the distal end of the catheter 38 shaft, and a balloon which is offset to one side of the _ _ CA 02207189 1997-0~-27 W O 96/20751 PCTrUS95116876 1 guidewire receiving tube and which is secured to that 2 tube only at the proximal and distal end sections 3 thereof. In use, a guidewire may be easily inserted into 4 or removed from the guidewire receiving tube via a proximal exit port. This ease of insertion and removal, 6 together with the distal positioning of the tube, endows 7 the catheter with a rapid exchange capability. The 8 offset positioning of the balloon, together with the 9 difference in size between the balloon and the guidewire receiving tube, causes a longit~ channel or groove 11 to appear along the boundary therebetween. This channel, 12 which allows blood to flow past the balloon when the 13 latter is in its inflated state, endows the catheter with 14 a perfusion capability. Thus, the dilation catheter of the invention has both a rapid exchange capability and a 16 perfusion capability.
17 In the preferred embodiment, the catheter shaft is 18 provided with two lumens. A first of these lumens is 19 used as an inflation lumen to conduct a flow of a suitable inflating fluid to the balloon. The second 21 lumen is used to carry a sti~fening wire that terminates 22 in proximity to the proximal exit port of the guidewire 23 receiving tube. This stiffening wire endows the catheter 24 with a measure of longitl~;n~l stiffness that allows it to better maintain its shape as it is being pushed 26 through the guiding catheter, and the torsional stiffness 27 that allows it to be rotated once it has reached its 28 final position. Terminating this stiffening wire in 29 proximity to the exit port of the guidewire is particularly advantageous, since it allows the guidewire 31 to take over the stiffening function of the stiffening 32 wire at approximately the point where the stiffening wire 33 ends. As a result, there is approximated a condition in 34 which the catheter has the advantages associated with the presence of a continuous full length stiffening wire 36 without the lack of rapid exchange capability that has, 37 prior to the present invention, been associated with the 38 presence of such a wire.

1 Because of the offset positioning of the balloon, 2 and because of the balloon's proximity to the guidewire 3 receiving tube and guidewire, the dilation catheter of 4 the invention has an improved ability to open stenoses.
This is because the proximity of the wire, and the 6 ability of the balloon to contact and ~ear against that 7 tube and wire, provide the kalloon with a firm foundation 8 from which to advance against a stenosis with increased 9 leverage and force. Advantageously, the balloon is specially shaped so that it can bear against the tube and 11 wire without deforming in a way that closes the above-12 mentioned perfusion channels.
13 The asymmetrical configuration resulting from the 14 offset positioning of the balloon also allows the catheter to be expanded into contact with a stenosis with 16 at least two different orientations. In a first 17 orientation, which may be described as a balloon 18 forward orientation, the relatively flexible outer 19 surface of the balloon is forced against the stenosis while the guidewire receiving tube and guidewire provide 21 leverage and support.
22 In a second orientation, which may be described as a 23 tube-forward orientation, the relatively in~lexible outer 24 surface of the guidewire reinforced tube is forced against the stenoses while the balloon acts as a 26 cushioning and force distributing foundation. In 27 accordance with the invention, either of these 28 orientations (or first one orientation and then the 29 other~, and all of the various intermediate orientations, may be established successively as necessary to give the 31 best result for particular stenoses by merely rotating 32 the catheter by appropriate amounts between inflations.
33 In accordance with an important secondary feature of 34 the present invention, both the balloon and the guide wire receiving tube are secured in abutting relationship 36 to respective parts of the distal end region of the 37 catheter shaft. More particularly, in the preferred 38 embodiment, the proximal end of the balloon is secured in CA 02207189 1997-0~-27 W O96/207~1 PCTrUS95/16876 1 abutting or end-to-end relationship with the part of the 2 distal end of the catheter shaft which surrounds the 3 inflation lumen thereof, and the proximal end of the tu~e 4 is secured in at least partially abutting relationship to the part of the distal end of the catheter shaft that 6 surrounds the stiffening lumen thereof. One advantage of 7 joining the catheter shaft, balloon and guidewire tube in 8 this way is that it causes the dilation catheter to have 9 surface which is relatively s~ooth and featureless, i.e., free of surface irregularities such as radial steps, and 11 which therefore has a reduced tendency to snag on 12 irregularities in the walls of a patient's blood vessels.
13 Another advantage is that it allows the ~imtl~ radial or 14 transverse ~;m~ion of the catheter to be smaller than would otherwise be the case and therefore usable with 16 smaller blood vessels.

18 Descri~tion of the Drawinqs 19 Other objects and advantages of the present invention will be apparent from the following description 21 and drawings, in which:
22 Fig. 1 is an enlarged cross-sectional view of the 23 end section of the preferred embodiment of a dilation 24 catheter constructed in accordance with the present invention, shown as it looks when it is inflated in an 26 unconfined environment;
27 Fig. lA is a fragmentary cross-sectional view of an 28 alternative embodiment of the dilation catheter of the 29 invention;
Fig. 2 is a cross-sectional view taken along section 31 2-2 of the catheter of Fig. l;
32 Fig. 3 is a cross-sectional view taken along section 33 3-3 of the catheter of Fig. l;
34 Fig. 4 is a cross-sectional view taken along section 4-4 of the catheter of Fig. 1;
36 Fig. 5 is a end view of the catheter of Fig. 1, 37 shown with the balloon in its deflated state;

1 Fig. 6 is a side ~iew of the dilation catheter of 2 Fig. 1, shown as it looks when it is inflated in a 3 confined environment;
4 Fig. 7 is a enlarged frasmentary exploded view of the catheter of Fig. 1, showing the mandrels and sleeve 6 used in bonding the proximal sections end of the balloon 7 and the guidewire tube to the distal end of the catheter 8 shaft, and g Fig. 8 is an enlarged fragmentary exploded view of the mandrel and sleeve used in bonding the distal end ll sections of the balloon and guidewire tube.

13 Description of the Preferred Embodiments 14 Referring to Fig. l there is shown an enlarged cross-sectional view of the distal portion of the 16 preferred embodiment of a dilation catheter 10 which has 17 been constructed in accordance with the present 18 invention. The remainder of catheter 10, which is not 19 shown, has a size and shape that is that same as that shown at section 2-2 of Fig. 1 and comprises an elongated 21 extension thereo~. Also not shown is the guiding 22 catheter which surrounds catheter 10 and which serves as 23 a protective sheath through which catheter 10 may be 24 inserted and withdrawn from the cardiovascular system of a patient. In use, the portion of the dilation catheter 26 shown in Fig. 1 projects out of the distal end of the 27 guiding catheter into the region of the stenosis to be 28 dilated. Thus, the portion of the dilation catheter 29 shown in Fig. 1 will be understood to be only the active, end portion of a much longer catheter apparatus.
31 In the embodiment shown in Fig. 1 catheter 10 32 includes a catheter shaft 20 which preferrably has two 33 lumens and which is composed of a suitable thermoplastic 34 polymeric material, such as polyethylene, nylon or polyethylene tetrafluoride ~PET). A first of these 36 lumens 20-1 has a generally circular cross-section, and 37 encloses a wire 2Z which imparts longitudinal and 38 torsional stiffness to the catheter, thereby facilitating CA 02207189 1997-0~-27 W O96/20751 PCTrUS95/16876 1 the insertion and maneuvering thereof. A second o~ these 2 lumens 20-2 has a generally semi-circular cross sect?on 3 (except at distal end 24 thereof) and serves as an 4 inflation lumen.
Dilation catheter 10 of Fig. 1 also includes a 6 guidewire receiving tube 30 and a dilation balloon 40.
7 In this embodiment, the pro~~ ends or end sections of 8 the tube 30 and balloon 40 are secured both to respective 9 distal end regions of catheter shaft 20 and to each other, the manner of attachment being such that the 11 proximal end of balloon 40 remains open and in fluid 12 communication with an inflating lumen 20-2. The distal 13 end sections of tube 30 and balloon 40 are attached only 14 to one another, the manner of attachment being such that the distal end of balloon 40 is sealed shut. Thus, fluid 16 can be introduced into or removed from balloon 40 only 17 through lumen 20-2 of catheter shaft 20.
18 For reasons that will be discussed later in 19 connection with the perfusion capability of the catheter, it is desirable that there not be any attachment between 21 the central or middle portion 30-1 of tube 30 and the 22 central portion 40-1 of balloon 40 and that balloon 40 be 23 given the bowed shape shown in Fig. 1 at the time it is 24 made. One advantage of the absence of such an attachment is that it endows the entire distal end of the catheter 26 with an increased flexibility. Another advantage of the 27 absence of such an attachment is that, together with a 28 bow shaped balloon, it causes a space or gap 40-2 to 29 appear between tube 30 and balloon 40 unless the latter are acted on by an external ~orce that tends to push them 31 toward one another. In Fig. 1 the dilation catheter is 32 shown as it looks when balloon 40 is in its inflated 33 state but is not subjected to such an external force. In 34 Fig. 6 the dilation catheter is shown as it looks when balloon 40 is inflated but is subjected to such an 36 external force. Thus, Fig. 1 may be thought of as 37 showing the appearance of the catheter when it is 38 inflated in an unconfined environment such as the open W O96120751 PCTAUS9~16876 1 air. While Fig. 6 may be thought of as showing the 2 appearance of the catheter when it is inflated in a 3 confined environment such as the interior of a patient's 4 blood vessel.
Balloon 40 is preferably preformed in the shape 6 shown in Fig. 1 (except that its distal end section will 7 be open and not flattened and closed as shown in Fig. l) 8 by in~lating a heated length of thermoplastic tubing 9 within an inflation mold having the desired shape.
Because, except for the particular shape shown in Fig. 1, 11 this process is well known to those skilled in the art, 12 it will not be described in detail herein. The shape 13 assumed by balloon 40 when it is fully de~lated, folded 14 and ready for insertion into a patient, is shown in Fig.

5.
16 Referring to the right half of the dilation catheter 17 of Fig. 1, it will be seen that the proximal end 42 of 18 balloon 40 is attached in abutting relationship to a 19 first distal end region 24 of shaft 20, and proximal end section 32 of guidewire receiving tube 30 is attached in 21 partly abutting and partly overlapping relationship to a 22 second distal end region 26 of shaft 20. The latter 23 region, which is formed by cutting away part of the upper 24 portion of the distal end section of catheter shaft 20, forms a step (most clearly shown in Figs 3 and 7) having 26 a transverse or radial section 26-1 and a longitll~; nA l 27 section 26-2 with a central trough 26-3, the latter being 28 an exposed section of lumen 20-1. Because this step 29 greatly increases the area of contact between the end section of tube 30 and shaft 20, it greatly increases the 31 structural integrity of the bond therebetween. This 32 increase is particularly important because part of the 33 pro~; m~ 1 end of tube 30 will be cut away to form an exit 34 port 34 through which a guidewire (represented by dotted line 50 in Fig. 1) will be passed each time the catheter 36 is used in a rapid exchange operation.
37 The positioning of tube 30 and balloon 40 in 38 abutting, or at least partly abutting, relationship to _ _ _ _ _ . _ . _ CA 02207189 1997-0~-27 W O96/20751 PCT~US95/16876 1 shaft 20 has a number of advantages. One of these is 2 that this positioning makes the transverse ~ ion of 3 the dilation catheter, smaller than would otherwise be 4 the case. Having a small transverse dimension is critically important to the use of the catheter since the

6 catheter is of benefit only i' it is small enough to fit

7 into the blood vessel in which the stenosis is located

8 and then through the stenosis itself.

9 Another advantage of positioning tube 30 and balloon 40 in abutting relationship to catheter shaft 20 is that 11 this positioning brings these elements substantially into 12 axial alignment or registry with catheter lumens 20-1 and 13 20-2, respectively. In the case of balloon 40, the axial 14 alignment is between the proximal end section 42 of the balloon and inflation lumen 20-2. As a result of a 16 thermal bonding step which will be discussed more fully 17 in connection with Fig. 7, this alignment is highly 18 accurate and facilitates a balloon-shaft joint whi-h is 19 substantially free of transverse steps that can cause the dilation catheter to snag during use.
21 In the case of tube 30, the axial alignment is 22 between the interior lumen of tube 30 and stiffening 23 lumen 20-1 of shaft 20. In the preferred embodiment this 24 alignment results from the fact that the diameter of tube Z5 30 is selected to approximate that of trough 26-3, within 26 which it is positioned when the tube and shaft are bonded 27 together. The advantage of such an alignment is that it 28 assures that, when guidewire 50 is threaded through the 29 lumen of tube 30 via proximal exit port 34 thereof, it is approximately collinear with stiffening wire 22 of shaft 31 20. This collinearity, together with the proximity of 32 exit port 34 to the distal end of wire 22, assures that 33 catheter 20 has stiffness properties which closely 34 approximate those of dilation catheters which have guidewires that run the full length thereof. Since 36 catheters of the latter type do not have a rapid exchange 37 capability, it will be seen that a catheter constructed 38 in accordance with the invention has both the W 096/20751 PCTrUS95J16876 1 advantageous properties of non-rapid ~rh~n~e catheters 2 and the advantageous properties of rapid exchange 3 catheters.
4 Although the above-described abutting relationships are preferred, the dilation catheter of the invention may 6 also be constructed with the balloon connected in 7 overlapping relationship to catheter shaft 20, as shown 8 in Fig. lA. More particularly, the proximal end 42 may 9 be fit over and around the distal end 24 of shaft 20, and 1~ the proximal end of tube 30 may be draped thereover into 11 contact with the upper surface of catheter 20. Because 12 the use of the catheter structure shown in Fig. lA
13 requires that the distal end of shaft 20 be shaped in 14 advance to fit into the proximal end of balloon 40, it is more difficult to produce than the catheter shown in Fig.
16 1. As a result, the catheter embodiment shown in Fig. lA
17 is not the preferred embodiment of the invention.
18 In accordance with an important feature of the 19 present invention, the dilat-on catheter is designed to exhibit a perfusion capability. As will be explained 21 more rully presently, this perfusion capability results, 22 in part, from the fact that b~lloon 40 is positioned to 23 one side of guidewire receiving tube 30 (i.e., is 24 disposed in an unsymmetrical or offset position) and, in part from the fact that balloon 40 and guidewire 26 receiving tube 30 have different sizes and therefore 27 different curvatures. Together these features assure 28 that channels or grooves appear on both sides of the 29 boundary between tube 30 and balloon 40. Provided only that these channels are large enough they are able to 31 conduct past the catheter a flow of blood which is great 32 enough to prevent a patient from being exposed to a risk 33 of injury while an ang~oplasty procedure is being 34 performed.
Referring to Fig. 4 these open channels occupy the 36 regions adjacent to the two edges B1 and B2 of the 37 boundary between tube 30 and balloon 40, and span the 38 full length of central section 40-1 of balloon 40.

CA 02207189 1997-0~-27 W O96/20751 PCTnUS9~/16876 1 Because of balloon 40's flexibility, it has a natural 2 tendency to move into and close off these c-h~nnels, 3 particularly when inflated within the confined space of a 4 blood vessel. This tendency is opposed, however, by the tendency of the balloon to eliminate any externally 6 imposed indentations in the surface thereof. In 7 accordance with the invention, the latter tendency is 8 caused to predominate over the former by forming a 9 concave (or saddle-like) inner surface in the balloon at the time of its manufacture. This concave inner surface 11 serves, in effect, to pre-distort the balloon so that it 12 takes on the desired undistorted shape when it is 13 inflated in the environment in which it is used.
14 In Fig. 1, which shows the shape of the catheter when balloon 40 is inflated in an unconfined environment, 16 this concavity has the effect of creating open space 40-17 2. In Fig. 6, which shows the shape of the catheter when 18 balloon 40 is inflated in a confined environment (such as 19 a blood vessel), this concavity has the effect of allowing the inner surface of balloon 40 to come to rest 21 against tube 40 without enveloping or overlapping tube 40 2~ to any significant degree. As a result, when the balloon Z3 is inflated within a blood vessel, the catheter assumes 24 the cross-sectional shape shown in Fig. 4 and thereby permits the perfusion of blood past balloon 40. (It will 26 be understood that the term "concave" refers to the shape 27 of the inner surface of the balloon as seen in a 28 longitudinal cross-section taken through the balloon and 29 tube; if the same surface is viewed in a transverse cross section through the balloon and tube, its shape will be 31 convex.) 32 While the above-described contact between tube 30 33 and the inner surface of balloon ~0 might be el;m;n~ted 34 altogether by forming this balloon with a great enough inner surface concavity, the preferred embodiment of the 36 catheter is specifically designed so that this contact 37 does occur. This is because this contact is used in 38 providing one of the important advantages of the CA 02207l89 l997-05-27 W O96/20751 PCTAUS95~16876 1 invention, namely: the ability of the tube to serve as a 2 relatively stiff foundation or base against which the 3 balloon may bear to gain le~erage for its advance against 4 a lesion, thereby better focusing that advance and reducing the pressure necessary to crack the lesion.
a 6 Without a firm, full length contact between the tube and 7 the balloon the ability to gain such leverage would be 8 greatly reduced or eliminated.
~ With a firm full length contact between the tube and the balloon, it is possible to take full advantage of the 11 unsymmetrical configuration which the catheter has by 12 virtue of the offset location of its balloon. The 13 catheter may, for example, be used with a "balloon 14 forward" orientation in which the outer surface of the balloon is advanced against a stenosis while the inner 16 surface thereof bears firmly against the relatively stifl 17 body of tube 30 for leverage. Alternatively, the 18 catheter may be used with a "tube forward" orientation in 19 which the outer surface o~ the tube is advanced against a stenosis while the inner surface thereof is firmly 21 supported by the inner surface of the balloon, which 22 thereby serves as a force distributing base. Such 23 orienta~ions, as well as any of the intermediate 24 orientations, may also be used successively by rotating the catheter through various angles between inflations.
26 Advantageously these rotations are facilitated by the 27 fact that the catheter has a shaft that is relatively 28 stiff as a result of the presence of stiffening wire 22.
29 It will therefore be seen that the catheter of the invention is more effective than previously available 31 catheters and may be used in a greater variety of 32 different ways than previously available catheters.
33 The manner in which the catheter of the invention is 34 constructed will now be described with reference to Figs.
7 and 8. Referring first to Fig. 7, there are shown in 36 disassembled form the component parts which are to be 37 brought together to form the proximal portion of the 38 catheter shown in Fig. 1, all parts being labelled with CA 02207189 1997-0~-27 W O96/20751 PCTrUS95/16876 1 the same numbers used therefor in Fig. 1. Also shown in 2 Fig. 7 are a number of auxiliary components which are 3 used in the making of the catheter and then removed.
4 Among these auxiliary components are metal mandrels M1 and M2, which serve to hold open the lumens of the 6 associated components during the thermal bonding thereof, 7 and a tubular sleeve C1 which serves to clamp the 8 illustrated components together while they are being 9 thermally bonded to one another.
When shaft 20, tube 30 and balloon 40 are ready to 11 be joined, balloon 30, which has previously been 12 preformed into the shape shown in Fig. 1, is pushed 13 against end region 24 of shaft 20 with mandrel M2 14 extending into lumen 20-2 thereof. This positioning of 1~ mandrel M2 assures that the balloon and shaft lumens will 16 take on the same shape auring the thermal ~onding 17 process. Tube 30, with mandrel M1 in place, is then laid 18 in trough 26-3 and pushed against end surface 26-1 of 19 shaft 20. Mandrel M1 preferably does not at this time extend into lumen 20-1 of shaft 20. This is be~ause it 21 is desirable for the upper portion of the wall of lumen 22 20-1 to meltingly seal the end of that lumen to the end 23 of stiffening wire 22, as showr in Figs~ 1 and lA. The 24 joined components are then preferrably held in this position by a sleeve C1 which is composed of a material 26 such as silicone rubber or tetrafluorethylene and which 27 is secured thereover in a manner known to those skilled 28 in the art. The joining of these components preferably 29 takes place through an opening in a heat shield S (shown in Figs. 1 and 8, but not in Fig. 7) which will protect 31 the central section balloon 0 from being deformed by the 32 heat used in the thermal bonding of the end section S
33 thereof.
34 Once the above-described preparatory steps have been taken, the joined components are thermally bonded by 36 heating them to a temperature dependent on the material 37 used and maintaining them at that temperature for a time 38 long enough for an intimate thermal bond to form W O96120751 PCTAUS9~/16876 1 therebetween. The formation of this bond preferrably 2 involves a degree of plastic flow which rounds off the 3 sharper surface features of the catheter and allows the 4 lumens of the balloon and sha~t to take on the same size and shape, as shown in Fig. 1. While this bond does not 6 necessarily obliterate all traces of the previously 7 existing boundaries between the joined components, it has 8 associated with it a considerably degree of cross-linking 9 which renders those boundaries substantially less distinct. The bonded area as a whole may therefore be 11 described as having a substantially integral or 12 monolithic structure.
13 When the bonding step has been completed and the 14 bonded area has cooled, sleeve Cl is cut away and discarded. After mandrel M1 has been at least partially 16 withdrawn, the exit port 34 for the guidewire may ther. be 17 formed by cutting a~ay a portion of the proximal end 18 section of tube 30. The area of the cut may, if desired, 19 then be sub~ected to 2 final thermai finishing step to assure that the edges of por~ 34 are smooth enough to 2i facilitate the easy passage of the guidewir~
22 there.hrough.
23 Referring to Fig. 8, there are shown those ~arts cf 24 tube 30 and balloon 40 which are to be bonded together to form the distal portion of the catheter of Fig. 1. These 26 parts include only the distal end sections of tube 30 and 27 balloon 40, the remainder of these components being 28 blocked from view by heat shield S. As shown in Fig. 8, 29 mandrel Ml is present within tube 30 to keep the latter open for the insertion and removal of the guidewire.
31 This distal end section of balloon 40 is flattened 32 against tube 30 to assure that it becomes sealed shut 33 during the bonding step.
34 In all other aspects the bonding of the distal end sections of tube 30 and balloon 40 is as described in 36 connection with the bonding of the proximal end sections 37 thereof, clamping member C2 being merely a smaller 38 version of previously described clamping member Cl.

CA 02207189 1997-0~-27 W O96/20751 PCTrUS95/16876 1 Because of this similarity, the bonding of the components 2 showing in Fig. 8 will not be further described herein.
3 In the preferred embodiment the tip of the catheter 4 is preferrably cut to form a tapered region 44 which facilitates its entry into blood vessels and into the 6 internal opening of a stenosis. If desired, this tapered 7 end may then be subjected to a final thermal fin;~hing 8 step to smooth out any sharp edges produced by the 9 cutting operation.
In view of the foregoing it will be seen that a 11 dilation catheter constructed in accordance with the 12 present invention provides a number of advantages over 13 previously known dilation catheters. One of these is 14 that it combines a rapid exchange capability with a lS perfusion capability. Another of these is that it 16 provides these capabilities in a catheter which has a 17 relatively small transverse dimension and a surface which 18 is smooth and free of irregularities. Still another of 19 these is that it provides these capabilities in a catheter which is relatively stiff over substantially its 21 entire length and there~ore easy to insert and 22 manipulate. Finally, the ca-heter of the invention 23 includes an offset balloon which, particularly in 24 combination with an associated guidewire, provides a more effective and more flexible way of dilating a stenoses.
26 While the invention has been described with 27 reference to particular specific embodiments, it will be 28 understood that the true spirit and scope of the 29 invention should be determined only with reference to the appended claims.

Claims

What is claimed is:

1. A catheter comprising:
a catheter shaft having a distal end, a proximal end and an inflation lumen;
a guidewire tube defining a guidewire lumen configured to receive a guidewire and having a proximal end and a distal end, the guidewire tube extending forwardly of the distal end of the catheter shaft and defining an exit port for receiving a guidewire; and an inflatable dilation balloon in communication with the inflation lumen of the catheter shaft and including proximal and distal ends, the balloon being attached to the guidewire tube in substantially side-by-side relationship;
wherein the balloon has a central portion that is unattached to the guidewire tube and has an inner surface that contacts the guidewire tube when the balloon is inflated within a patient, but bows away from the guidewire tube when the balloon is inflated outside of a patient.

2. A catheter according to claim 1, wherein the catheter shaft includes an auxiliary lumen in which is positioned a stiffening wire extending from the proximal end of the catheter shaft to a location adjacent the exit port in said guidewire tube.

3. A catheter according to claim 2, wherein the stiffening wire is substantially collinear with the guidewire lumen in the guidewire tube.

4. A catheter according to claim 2, wherein the catheter shaft has a circular cross-section enclosing the inflation lumen and the auxiliary lumen.

5. A catheter according to claim 2, wherein the guidewire tube is sealed against a distal end of the stiffening wire located adjacent the exit port in the guidewire tube.

6. A catheter according to claim 1, wherein the balloon is formed as a separate member from the catheter shaft, and the proximal end of the balloon is secured in abutting relationship to the distal end of the catheter shaft.

7. A catheter according to claim 1, wherein the balloon is formed as a separate member from the catheter shaft, and the proximal end of the balloon is secured in overlapping relationship to the distal end of the catheter shaft.

8. A catheter according to claim 1, wherein the balloon is formed as a separate member from the catheter shaft and the proximal end of the balloon is secured to the distal end of the catheter shaft, and the guidewire tube overlaps at least portions of the proximal end of the balloon and the distal end of the catheter shaft.

9. A catheter according to claim 1, wherein the catheter shaft includes a stepped portion which supports the proximal end of the guidewire tube such that a portion of the guidewire tube extends past said stepped portion in a cantilever manner.

10. A catheter according to claim 9, wherein the stepped portion is at the distal end of the catheter shaft and includes a trough and the proximal end of the guidewire tube is disposed in said trough.

11. A catheter according to claim 1, wherein the balloon includes inner and outer surfaces defining curvatures such that a longitudinal cross section through the balloon defines concave surfaces with respect to the guidewire tube.

12. A catheter according to claim 1, further comprising a guidewire disposed in said guidewire tube.

13. A catheter comprising:
a catheter shaft defining an inflation lumen;
a guidewire lumen having a proximal end and a distal end, the proximal end including a port for receiving a guidewire;
a balloon including a proximal end, a distal end and an inflatable portion, the inflatable portion of the balloon being in fluid communication with the inflation lumen of said catheter shaft; and a stiffening wire disposed in the catheter shaft, the stiffening wire having proximal and distal ends;
the distal end of the stiffening wire terminating at the port in the guidewire lumen with said stiffening wire being substantially parallel to the guidewire lumen, such that when a guidewire is inserted through said port and into the guidewire lumen the stiffening wire and the guidewire combine to stiffen the catheter over substantially the entire length thereof.

14. A catheter according to claim 13, further comprising a separate guidewire tube which defines said guidewire lumen and is secured to the catheter shaft and balloon.

15. A catheter according to claim 13, further comprising a guidewire disposed in said guidewire lumen.

16. A catheter according to claim 15, wherein the guidewire is substantially collinear with the stiffening wire.

17. A catheter according to claim 13, wherein the catheter shaft includes a stepped portion and the port in the guidewire lumen is located adjacent said stepped portion of the catheter shaft.

18. A catheter according to claim 13, wherein the distal end of the stiffening wire is sealed from the port in the guidewire lumen.

19. A catheter according to claim 13, wherein the balloon includes inner and outer surfaces and the inner surface is located nearer the guidewire lumen than the outer surface, wherein at least a section of the inner surface of the balloon is unattached to the catheter.

20. A catheter for use with a guidewire and guiding catheter, the catheter comprising:
an elongated catheter shaft which defines an inflation lumen and has a distal end and a proximal end;
a guidewire receiving tube which has a length that is small in relation to the length of said shaft, the guidewire receiving tube having a distal end and a proximal end;
a dilation balloon which defines an inflation lumen and has a shape that enables it to be attached in side-by-side relationship to said tube, the dilation balloon having a distal end and a proximal end;
wherein the proximal end of said tube is secured to the distal end of said shaft, the proximal and distal ends of said balloon are secured to the proximal and distal ends of said tube, and the inflation lumen of said balloon is in fluid communication with the inflation lumen of said shaft;
wherein said tube defines an exit port through which a guidewire may be passed; and wherein said shaft also defines an auxiliary lumen and a stiffening wire is disposed in the auxiliary lumen, the stiffening wire having a distal end terminating in proximity to said exit port.