USE THEREOF

FIELD OF THE INVENTION

This invention relates in general to the field of medical catheters having inflatable balloons and more particularly to a catheter having an improved intussuscepting balloon structure.

BACKGROUND OF THE INVENTION

Catheters are used in various interventional procedures for delivering therapeutic means to a treated site (e.g., body organ or passageway such as blood vessels). In many cases, a catheter with a small distal inflatable balloon is guided to the treated site. Once the balloon is in place it is inflated by the operator for affixing it in place, for expanding a blocked vessel, for placing treatment means (e.g., stent) and/or for delivering surgical tools (e.g. knives, drills etc.) to a desired site. In addition, catheter systems have also been designed and used for retrieval of objects such as stents from body passageways. Two basic types of catheter have been developed for intravascular use: other-the-wire

(OVT) catheters and rapid-exchange catheters.

OVT catheter systems are characterized by the presence of a full-length guide wire, such that when the catheter is in its in situ working position, said guide wire passes through the entire length of a lumen formed in, or externally attached to, the catheter. OVT systems have several operational advantages which are related to the use of a full length guide wire, including good stiffness and pushability, features which are important when maneuvering balloon catheters along tortuous and/or partially occluded blood vessels. U.S. Pat. No. 6,039,721 to Johnson et al. describes a balloon catheter system comprising two concentrically-arranged conduits, with a balloon connected between the distal regions thereof. The catheter system permits both expansion/deflation of the balloon and alteration in the length of the balloon when in situ, such that the balloon may be moved between extended and intussuscepted conformations. The catheter system is constructed in order that it may be used for two main purposes: firstly, treatment (i.e. expansion) of different-length stenosed portions of blood vessels with a single balloon and secondly, the delivery of either stents or medication to intravascular lesions, wherein the stent or medication is contained within the distally-intussuscepted portion of the balloon. When used for multiple, differing-length lesion expansion, the balloon is inserted into blood vessel in a collapsed, shortened, intussuscepted conformation, and is advanced until it comes to rest in the region of the shortest lesion to be treated. The balloon is then inflated and the lesion treated (i.e. expanded). Following deflation of the balloon, the distal end of the catheter system is moved such that the balloon becomes positioned in the region of the next—shortest lesion to be treated. The effective length of the balloon is then increased by moving the inner conduit in relation to the proximal conduit, following which the balloon is again inflated and the lesion treated. In this way, a series of different length stenoses, in order from the shortest to the longest, may be treated using a single balloon. When used for stent delivery, the stent is pre-loaded into a proximal annular space formed as a result of balloon intussuscepting. The balloon is then moved to the desired site and the stent delivered by means of moving the inner conduit distally (in relation to the outer tube), thereby "unpeeling" the stent from the catheter.

WO 00/38776 discloses a dual-conduit balloon catheter system similar in basic design to that described above in relation to U.S. patent 6,039,721. This catheter system is intended for use in a vibratory mode in order to break through total occlusions of the vascular lumen. In order to fulfill this aim, the outer conduit has a variable stiffness along its length, while the inner conduit. In addition, the inner conduit while being intrinsically relatively flexible is stiffened by the presence of axial tensioning wires. These conduit design features are used in order to permit optimal translation of vibratory movements of the proximal end of the inner conduit into corresponding vibration of the distal tip thereof.

Rapid exchange ("monorail") catheters typically comprise a relatively short guide wire lumen provided in a distal section thereof, and a proximal guide wire exit port located between the catheter's distal and proximal ends. This arrangement allows exchange of the catheter over a relatively short guide wire, in a manner which is simple to perform and which can be carried out by a single operator. Rapid exchange catheters have been extensively described in the art, for example, U.S. Patents 4,762, 129, 4,748,982 and EP0380873.

Rapid exchange catheters are commonly used in percutaneous transluminal coronary angioplasty (PTCA) procedures, in which obstructed blood vessels are typically dilated by a distal balloon mounted on the catheter's distal end. A stent is often placed at the vessel's dilation zone to prevent reoccurrences of obstruction therein. The dilation balloon is typically inflated via an inflation lumen which extends longitudinally inside the catheter's shaft between the dilation balloon and the catheter's proximal end.

The guide wire lumen passes within a smaller section of the catheter's shaft length and it is accessed via a lateral port situated on the catheter's shaft. This arrangement, wherein the guide wire tube is affixed to the catheter's shaft at the location of its lateral port, usually prevents designers from developing new rapid exchange catheter implementations which requires manipulating its inner shaft. For example, extending or shortening the catheter's length during procedures may be advantageously exploited by physicians to distally extend the length of the catheter into a new site after or during its placement in the patient's artery, for example in order to assist with the passage of tortuous vessels or small diameter stenoses, or to allow in-situ manipulation of an inflated balloon at the distal end of the catheter.

Published International Patent Application, Publication No. WO 2005/102184 discloses a catheter having a Tollable expandable element. Published International Patent applications, Publication Nos. WO 2007/004221, WO 2007/042935 , WO 2008/004238 and WO 2008/004239, all five published international applications are incorporated herein by reference in their entirety for all purposes, disclose various types of catheters and catheter systems having intussuscepting balloon-like inflatable members which may be used, inter alia, to treat plaque by balloon inflation while efficiently and safely collecting plaque debris and other particulate matter from the lumen of pathologically-involved blood vessels and to remove such particles and particulate matter from the blood vessel.

Published International Patent Applications, WO 210/001404 and WO 2010/001405 incorporated herein by reference in their entirety disclose rapid exchange catheters having stepped and corrugated intussuscepting balloons, respectively. Reference is now made to Figs. 1 and 2. Fig. 1 is a cross-sectional diagram schematically illustrating the forces acting on an inflated prior art intussuscepting balloon and on some catheter components during the intussuscepting of the balloon. Fig. 2 is a schematic cross sectional diagram of the balloon of Fig. 1 after completion of the balloon intussuscepting, illustrating a collapse of the proximal end of the balloon.

It is noted that in Figs. 1 -2 of the present Application the letter P denotes the proximal end of the balloon 2 (the side of the balloon attached to the outer conduit 6 of the catheter), and the letter D denotes distal end of the balloon 2 (the side of the balloon attached to the inner conduit 8 of the catheter). The construction and operation of the balloon 2 of the balloon catheter 10 are disclosed in detail in the above referenced patent applications. Typically, in operation, the balloon 2 and catheter 10 are inserted into a blood vessel (not shown in Figs 1 -2). The insertion may be performed through a suitable Introducing sheath, or a suitable guiding catheter, as is known in the art. Typically (but not obligatorily), a guide wire may be used as is known in the art. After the balloon 2 is properly positioned in the portion of the vessel to be treated, the. balloon 2 may be inflated with a suitable fluid to a nominal inflation pressure of 6-8 atmospheres (other, different pressure values may also be used) to treat a plaque or atheromatous vessel constriction. After inflation of the balloon 2 and treatment of the blood vessel, the pressure inside the balloon may be somewhat reduced to a lower value (typically the lower pressure value is about 2 atmospheres, but other different pressure values may also be used) to enable intussuscepting of the balloon. The inner conduit 8 of the catheter 10 is pulled in the proximal direction while the outer conduit 6 is held stationary, to cause a collapse of the distal portion of the balloon and invagination (and intussuscepting) of the distal end of the balloon 2 to form a space 12 within the balloon 2. During the pulling of the inner conduit 8 in the proximal direction, the inner conduit 8 is under tension. The pulling force Fl is transmitted to the outer conduit 6 by the walls of the balloon 2 along the direction schematically illustrated in Fig. 1 by the arrows 14. Due to the transmitted force, the outer conduit 6 is under compression. The compression causes the outer conduit 6 to shorten slightly, since due to it's elasticity it becomes compressed and therefore shortens (typically by approximately 1-2 mm for a standard catheter length which is in the range of about 70 to 180 centimeters). Thus, the compressed outer conduit 6 may act like a spring. After completion of intussuscepting of the balloon 2, the balloon 2 is further deflated at a high rate by further withdrawing additional fluid from within the balloon 2 typically by using a standard indeflator (not shown) which is fluidically connected to the inside space of the balloon 2. During this stage of high rate deflating and internal pressure reduction in the balloon 2, the balloon 2 may become a destabilized such that it cannot hold any more the expansion of the compressed outer conduit 6 towards the distal direction. This distal expansion moves the proximal end of the balloon 2 attached to the outer conduit 6 in the distal direction and may result in collapse of the proximal balloon end as illustrated in Fig. 2. The slight invagination 15 of the proximal portion of the balloon 2 in Fig. 2 schematically represents the results of such "proximal collapse".

While such balloon proximal end collapse is quite rare, it is undesirable because it may interfere with the withdrawing of the collapsed balloon out of the body through the guiding catheter (not shown) or introducing sheath (not shown) due to possible snagging of the cup-like invagination 15 of the collapsed proximal end of the balloon 2 around the orifice of the guiding catheter or introducing sheath (not shown in Fig. 2). Furthermore, while the above described reasons may be likely to contribute to such proximal collapse events, it may be possible that under certain conditions and balloon structures, proximal collapse may occasionally occur at the beginning of the application of pulling force to the inner conduit 8, while the balloon 2 is still inflated, with the same undesired results.

Thus, irrespective of the precise physical mechanism underlying proximal collapse of such intussuscepting balloons, there is a clear need and it would be highly desirable to reduce the probability of balloon proximal end collapse as much as possible to further even further reduce or avoid balloon withdrawal complications. US published application number 2003/002821 1 to Crocker et al., disclosed interventional catheters having balloons with stepped configurations in which different parts of the balloon may have different diameters. However, the balloons are not of the intussuscepting type and no mechanism for intussuscepting the balloons is provided. SUMMARY OF THE INVENTION

There is therefore provided, in accordance with an embodiment of the catheters of the present application a catheter including an inflatable intussuscepting balloon. The catheter includes an outer conduit and an inner conduit disposed within the outer conduit and suitable for total or partial passage over a guide-wire. The inner conduit includes at least one movable part movably disposed within the lumen of the outer conduit and has a distal end extending beyond the distal end of the outer conduit. The catheter also includes an inflatable balloon having a proximal margin sealingly attached to the outer surface of the distal end of the outer conduit and a distal margin sealingly attached to the outer surface of the distal portion of the at least one movable part of the inner conduit. The inflatable balloon includes a proximal portion, a middle portion and a distal portion. One portion of the balloon selected from the proximal portion and the distal portion is a reinforced portion having at least some reinforced part for increasing the force required to initiate collapse of the reinforced portion. The remaining portion of the distal portion and the proximal portion of the balloon is a non-reinforced portion. The catheter includes a moving mechanism for axially moving the movable part of the inner conduit within the outer conduit, The catheter also includes a fluid port for the introduction of an expansion fluid into the space formed between the outer conduit and the inner conduit and therefrom into the lumen of the balloon and for the removal of the fluid from the space and from the lumen.

Furthermore, in accordance with an embodiment of the catheter of the present application, the inner conduit includes a single inner tube movably disposed within the outer conduit and having a proximal end sealingly disposed within the proximal end of the outer conduit. The moving mechanism permits axial movement of the inner conduit within the outer conduit by pulling the inner conduit proximally or by pushing the inner conduit distally within the outer conduit.

Furthermore, in accordance with an embodiment of the catheter of the present application, the catheter also includes a pressure regulating mechanism for reducing pressure changes within the space of the catheter upon axial movement of the movable part of the inner conduit in relation to the outer conduit. Furthermore, in accordance with an embodiment of the catheter of the present application, the pressure regulating mechanism is selected from:

1 ) A pressure regulating mechanism including a syringe-like structure disposed at the proximal end of the catheter, the syringe-like structure includes a piston-like member, the syringe-like structure is in fluidic communication with the space, the piston like member is movably disposed within the syringe-like structure and is mechanically coupled to the means for axially moving the at least one movable part of the inner conduit, such that when the movable part of the inner conduit is moved proximally the amount of inflation fluid ejected from the balloon during the intussuscepting thereof is accommodated within the syringe-like structure.

2) An outlet in fluidic communication with the lumen of the inflatable balloon and having an opening and a compliant member sealingly attached to the opening for at least partially relieving over-pressure in the lumen of the catheter and the balloon.

3) An over-pressure valve outlet in fluidic communication with the lumen of the inflatable balloon and an over-pressure valve disposed within the over-pressure outlet to allow discharging of fluid from the lumen when over-pressure conditions develop in the lumen of the catheter and the balloon.

4) An expandable or inflatable portion of the outer conduit capable of expanding when over-pressure conditions occur in the lumen of the balloon to at least partially relieve the over-pressure in the lumen of the catheter and the balloon.

5) A hydraulic accumulator configured for being controllably fluidically connected and disconnected from the space and the lumen of the balloon of the catheter and the balloon.

Furthermore, in accordance with an embodiment of the catheter of the present application, the inner conduit includes a tube having a proximal angled portion piercing the walls of the outer conduit and the movable part slidably attached to the distal portion of the fixed tube. The moving mechanism permits unhindered axial movement of the movable part of the inner conduit within the outer conduit, such that the movement is not hindered by the passage of the angled portion of the inner conduit through the outer conduit. Furthermore, in accordance with an embodiment of the catheter of the present application, the moving mechanism includes a sealing sleeve sealingly attached to the angled portion of the inner conduit and slidably fitted around the outer conduit, such that the angled portion of the inner conduit passes firstly through an elongated aperture in the wall of the outer conduit and secondly through a tightly sealed aperture in the sealing sleeve, such that upon axial movement of the movable part of the inner conduit, the sealing sleeve is capable of preventing leaking of inflation fluid through the elongated aperture.

Furthermore, in accordance with an embodiment of the catheter of the present application, the moving mechanism is provided by a two-part inner conduit construction. A first proximal part of the two-part inner conduit includes a non-movable inner tube having the angled portion and fixedly attached to the outer conduit. The second distal part of the two-part inner conduit includes a slidable internal tube disposed within the non-movable inner tube.

Furthermore, in accordance with an embodiment of the catheter of the present application, the moving mechanism is provided by a two-part inner conduit construction. A first proximal part of the two-part inner conduit includes a non-movable inner tube including the angled portion. A second distal part of the two-part inner conduit includes a slidable internal tube disposed over the non-movable inner tube.

Furthermore, in accordance with an embodiment of the catheter of the present application, the moving mechanism is provided by a two-part inner conduit construction. The two-part inner conduit includes a non-movable inner tube including the angled portion and a slidable intermediate tube movably disposed between the non movable inner tube and the outer conduit. The slidable intermediate tube has an elongated longitudinal opening on its side through which the angled portion passes. The distal end of the intermediate tube is the portion of the inner conduit that extends beyond the distal end of the outer conduit. The distal margin of the balloon is sealingly attached to the outer surface of the distal end of the intermediate tube. The proximal end of the intermediate tube sealingly passes through and extends beyond the proximal end of the outer conduit such that the moving mechanism is the proximal end of the intermediate tube.

Furthermore, in accordance with an embodiment of the catheter of the present application, the moving mechanism is provided by a three-part inner conduit construction. The three-part inner conduit includes: A first non-movable hollow tube including the angled portion at its proximal portion and having a distal end, a second non-movable hollow inner tube having a proximal end and a distal end, the second inner tube is sealingly disposed within the distal end of the first non-movable inner tube, and a third slidable inner tube slidably disposed over the distal end of the second non-movable hollow tube, the third slidable inner tube has a distal end extending beyond the distal end of the outer conduit and the distal margin of the balloon is attached to the outer surface of the portion of the distal end of the third inner tube extending beyond the distal end of the outer conduit.

Furthermore, in accordance with an embodiment of the catheter of the present application, the outer conduit includes a lateral opening therein and the moving mechanism includes a sealing sleeve internally disposed within the outer conduit and attached to the angled portion of the inner conduit. The sealing sleeve is sealingly fitted within the outer conduit, such that the angled portion of the inner conduit passes firstly through the wall of the sealing sleeve, and secondly through the lateral opening of the outer conduit, in such a manner that upon axial movement of the inner conduit and the sealing sleeve, the sealing sleeve is capable of preventing leaking of inflation fluid through the lateral opening.

Furthermore, in accordance with an embodiment of the catheter of the present application, the inflatable balloon is characterized by having, in its inflated state, a shape which is capable of guiding the intussuscepting of the distal end thereof upon proximal movement of the movable part of the inner conduit in relation to the outer conduit.

Furthermore, in accordance with an embodiment of the catheter of the present application, at least one poertion of the distal portion and proximal portion of the balloon has a shape selected from the group consisting of a distal taper with a rounded distal extremity, a dome-like portion, a truncated dome-like portion, a conical portion, a frusto- conical portion, a corrugated dome-like portion, a corrugated conical portion, a corrugated frusto-conical portion, a corrugated truncated dome-like portion, and any combinations thereof.

Furthermore, in accordance with an embodiment of the catheter of the present application, the reinforced portion is selected from: 1) A reinforced portion having at least one part thereof which has a wall thickness greater than the wall thickness of the part of the non-reinforced portion. 2) A reinforced portion including at least one part having a wall thickness which is greater than the thickness of the part having the maximal wall thickness of the non-reinforced portion. 3) A reinforced portion having at least one cross-linked part thereof. The reinforced portion has a greater resistance to a collapsing force than the resistance of the non-reinforced portion 4) A reinforced portion having a reinforcing member attached to the internal surface of the reinforced portion within the balloon. 5) A reinforced portion having a reinforcing member attached to the external surface of the reinforced portion disposed outside of the balloon.

There is also provided in accordance with an embodiment of the balloons of the present application, an inflatable intussuscepting balloon for use in a balloon catheter. The balloon has a proximal portion, a middle portion and a distal portion. One portion of the balloon selected from the proximal portion and the distal portion is a reinforced portion having at least some reinforced part for increasing the force required to initiate collapse of the reinforced portion. The remaining portion of the distal portion and the proximal portion of the balloon is a non-reinforced portion.

Furthermore, in accordance with an embodiment of the balloon of the present application, the reinforced portion is selected from the group consisting of: 1 ) A reinforced portion having at least one part thereof which has a wall thickness larger than the wall thickness of the part of the remaining non-reinforced portion 2) A reinforced portion including at least one part having a wall thickness which is greater than the thickness of the part having the maximal wall thickness of the non-reinforced portion 3) A reinforced portion having at least one cross-linked part thereof, the reinforced portion has a greater resistance to a collapsing force than the resistance of the non-reinforced portion 4) A reinforced portion having a reinforcing member attached to the internal surface of the reinforced portion within the balloon, 5) A reinforced portion having a reinforcing member attached to the external surface of the reinforced portion disposed outside of the balloon.

There is also provided in accordance with an embodiment of the methods of the present application, a method of constructing an intussusceptible balloon catheter. The method includes the steps of: 1 ) Providing a catheter having an outer conduit and an inner conduit disposed within the outer conduit and suitable for total or partial passage over a guide-wire. The inner conduit includes at least one movable part movably disposed within the lumen of the outer conduit and having a distal end extending beyond the distal end of the outer conduit 2) Providing an inflatable balloon having a proximal margin and a distal margin. The inflatable balloon includes a proximal portion, a middle portion and a distal portion. One portion of the balloon selected from the proximal portion and the distal portion is a reinforced portion having at least some reinforced part for increasing the force required to initiate collapse of the reinforced portion. The remaining portion of the distal portion and the proximal portion of the balloon is a non-reinforced portion 3) Sealingly attaching the proximal margin of the balloon to the outer surface of the distal end of the outer conduit and sealingly attaching the distal margin of the balloon to the outer surface of the portion of the inner conduit that extends beyond the distal end of the outer conduit such that the lumen of the balloon is in fluidic communication with the space defined between the outer conduit and the inner conduit. The attaching is performed such that the non-reinforced portion is capable of preferentially collapsing upon proximal movement of the movable part of the inner conduit in relation to the outer conduit.

Furthermore, in accordance with an embodiment of the method of constructing the catheter of the present application, the step of providing includes the step of reinforcing the reinforced portion prior to the sealing.

Furthermore, in accordance with an embodiment of the method of constructing the catheter of the present application, the step of providing includes a step selected from the following steps : 1) Providing a balloon in which the reinforced portion has at least one part thereof which has a wall thickness larger than the wall thickness of the part of the remaining non-reinforced portion 2) Providing a balloon in which the reinforced portion including at least one part having a wall thickness which is greater than the thickness of the part having the maximal wall thickness of the non-reinforced portion 3) Providing a balloon in which the reinforced portion has at least one cross-linked part thereof. The reinforced portion has a greater resistance to a collapsing force than the resistance of the non-reinforced portion 4) Providing a balloon in which the reinforced portion has a reinforcing member attached to the internal surface of the reinforced portion within the balloon 5) Providing a balloon in which the reinforced portion has a reinforcing member attached to the external surface of the reinforced portion disposed outside of the balloon. There is also provided in accordance with an embodiment of the methods of the present application, a method for collecting debris from an internal passage of a mammalian subject. The method includes the steps of: a) inserting a balloon catheter into the internal passage, and advancing the catheter until the distal end thereof has reached a site at which it is desired to collect debris, the balloon catheter includes an outer conduit and an inner conduit disposed within the outer conduit and suitable for total or partial passage over a guide-wire. The inner conduit includes at least one movable part movably disposed within the lumen of the outer conduit and having a distal end extending beyond the distal end of the outer conduit. The catheter also includes an inflatable balloon having a proximal margin sealingly attached to the outer surface of the distal end of the outer conduit and a distal margin sealingly attached to the outer surface of the distal portion of the at least one movable part of the inner conduit. The inflatable balloon includes a proximal portion, a middle portion and a distal portion. One portion of the balloon selected from the proximal portion and the distal portion is a reinforced portion having at least some reinforced part for increasing the force required to initiate collapse of the reinforced portion and the remaining portion of the distal portion and the proximal portion of the balloon is a non-reinforced portion. The catheter also includes a moving mechanism for axially moving the at least one movable part of the inner conduit within the outer conduit and a fluid port for the introduction of an expansion fluid into the space formed between the outer conduit and the inner conduit and therefrom into the lumen of the balloon and for the removal of the fluid from the space and from the lumen. b) Inflating the balloon with expansion fluid. c) Moving the movable part of the inner conduit in a proximal direction using the moving mechanism, such that the non-reinforced portion collapses and the balloon intussuscepts forming a cavity for collecting the debris. d) Deflating the balloon, to increase the volume of the cavity to collect and trap additional debris within the cavity, and e) Removing the balloon catheter from the internal passage together with the entrapped debris.

Furthermore, in accordance with an embodiment of the method of collecting debris of the present application, the internal passage is a blood vessel. Finally, in accordance with an embodiment of the method of collecting debris of the present application, the catheter includes a pressure regulating mechanism for reducing pressure changes within the catheter when the movable part of the inner conduit is moved proximally within the outer conduit while the balloon is inflated and the fluid port is closed. The step of moving includes moving the movable part of the inner conduit in a proximal direction for collapsing the non-reinforced portion of the balloon to form a cavity within the balloon into which debris is collected and entrapped, without inducing substantial pressure changes within the lumen of the balloon during the intussuscepting of the balloon.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is herein described, by way of example only, with reference to the accompanying drawings, in which like components are designated by like reference numerals, wherein: Fig. 1 is a cross-sectional diagram schematically illustrating the forces acting on an inflated prior art intussuscepting balloon and on some catheter components during the intussuscepting of the balloon;

Fig. 2 is a schematic cross sectional diagram of the balloon of Fig. 1 after completion of the balloon intussuscepting, illustrating a collapse of the proximal end of the balloon; Fig. 3 is a schematic cross-sectional diagram illustrating part of an intussuscepting balloon catheter including a balloon having a proximal portion with a wall thickness greater than the wall thickness of its distal portion, in accordance with an embodiment of the catheter of the present application;

Fig. 4 is a schematic cross-sectional diagram illustrating part of an intussuscepting balloon catheter including a balloon having a thick proximal portion with a non-uniform, linearly varying wall thickness, in accordance with an embodiment of the catheter of the present application;

Fig. 5 is a schematic cross-sectional diagram illustrating part of an intussuscepting balloon catheter including a balloon having a thick proximal portion with a non-uniform, non-linearly varying wall thickness, in accordance with another embodiment of the catheter of the present application; and

Fig. 6 is a schematic cross-sectional diagram illustrating part of an intussuscepting balloon for use in a balloon catheter. The balloon has a non-uniform wall thickness, a truncated conical proximal portion and a partially rounded distal portion, in accordance with another embodiment of the balloon catheters of the present application.

Fig. 7 is a schematic cross-sectional diagram illustrating part of an intussuscepting balloon catheter including a balloon having a distal portion with a wall thickness greater than the wall thickness of its proximal portion, in accordance with an embodiment of the catheter of the present application; Fig. 8 is a schematic cross-sectional diagram illustrating part of an intussuscepting balloon catheter including a balloon having a reinforced proximal portion, in accordance with an embodiment of the catheter of the present application;

Fig. 9 is a schematic diagram illustrating reference points used in measuring the distances of points at which wall thickness was experimentally determined for a series of balloons manufactured with non-uniform wall thickness, in accordance with an embodiment of the balloons of the present application;

Fig. 10 is a schematic cross diagram illustrating part of the experimental apparatus used for determining the force of collapse of distal and/or proximal balloon portions in experiments;

Fig. 1 1 is a schematic diagram illustrating a side view of a typical balloon having a non-uniform wall thickness therealong used in the experiments and cross-sectional views taken at various positions therealong;

Fig. 12 is a schematic bar graph illustrating the wall thickness of the balloon of Fig. 10 as measured at the cross-sections A-A to L-L of Fig. 1 1 ;

Fig. 13 is a schematic bar graph illustrating the mean force required for collapsing the proximal cone and distal cone of a typical balloon constructed in accordance with an embodiment of the present application;

Fig. 14 is a schematic graph illustrating the dependence of the mean force required for proximal cone collapse on the mean wall thickness of the balloon at the cross-section B-B of Fig. 1 1 ;

Fig. 15 is a schematic graph illustrating the dependence of the mean force required for proximal cone collapse on the mean wall thickness of the raw tubing used for blow- molding of the balloons; and Fig. 16 is a schematic cross-sectional diagram illustrating part of an intussuscepting balloon catheter including a balloon having a reinforced proximal portion, in accordance with another embodiment of the catheter of the present application. DETAILED DESCRIPTION OF THE INVENTION

Notation Used Throughout

The following notation is used throughout this document.

Term Definition

Atm Atmosphere mm millimeter

N Newton

OVT Over the wire

PA Polyamide

PABA Polyamide block amides

PE Polyethylene

PEBA Polyether block amides

PET Polyethylene terephthalate

PTCA Percutanous transluminal coronary angioplasty

RE Rapid exchange

It is noted that in the following description and in the claims of the present application, the terms "distal" and "proximal" are defined as follows: the catheter side or end which is inserted into the body first is referred to as the distal side or distal end and the trailing side or end of the catheters part of which remains outside the body after insertion of the catheter is referred to as the proximal side. Similarly, the side or portion or part of the balloon which is first inserted into the body is referred to as the distal balloon side or portion or part (in some of the drawing Figures the reference character D indicates the distal side and the reference character P indicates the proximal side.

It is further noted that the terms "sleeve-like element" and "balloon" in the singular and plural forms are interchangeably used in the present application. The term "sleeve- like element" is typically used throughout the application to refer to the element or balloon before it is assembled into the balloon catheter, while the term "balloon" is used to refer to the same sleeve-like element after it has been assembled into the balloon catheter. However, for the sake of convenience, these two terms may also be used interchangeably in the application and in the claims irrespective of whether the balloon is show as part of a catheter or not and irrespective of whether the sleeve-like element is shown alone or as attached to a catheter In the following description, the terms "conduit" and "tube" are used interchangeably throughout the application wherein a conduit may include multiple tubes in various relationship thereof. For example, a conduit may include two or three tubes of different diameters wherein one of the tubes may be movably or fixedly disposed within one or more of the other tubes (such as the inner conduit having a movable part disclosed in PCT published application WO 2007/004221). However, it is noted that the term conduit may also be used to define a single tube ( for example, the inner conduit 8 of the catheters 20, 30, 40, 60, 70 and 80 of Figs 3, 4, 5, 7, 8 and 16 respectively). Thus, as defined herein, the term "conduit" may also include single tubes (such as the outer conduit 6 of Fig. 3) and any component comprising one or more parts or tubes in different moving or fixed relationships therebetween.

The present application discloses catheter systems with intussuscepting inflatable elements (such as, for example, inflatable intussuscepting balloons) specifically configured to reduce the probability of occurrence of collapse of the proximal end or proximal portion the inflatable element (such as, but not limited to the balloon 2 illustrated in Fig. 2) when the inner conduit (such as, for example, the inner conduit 6 of Figs. 3-5) of such catheters is pulled in the proximal direction.

The present application also discloses catheter systems with intussuscepting inflatable elements (such as, for example, inflatable intussuscepting balloons) specifically configured to reduce the probability of occurrence of collapse of the distal end or distal portion the inflatable element (such as, but not limited to the balloon 62 illustrated in Fig. 7).

The method for constructing a catheter with a higher probability of collapse of either a proximal or a distal portion of the intussuscepting balloon of the catheter when an axially directed longitudinal force is applied to the balloon of the catheter includes reinforcing either the distal portion or the proximal portion of the balloon, respectively.

Such balloons are also interchangeably referered to as "reinforced balloons" or as balloons having a reinforced end portion or a reinforced part. Such reinforcing may be achieved by using several different methods. In accordance with one embodiment, the reinforcing of the selected balloon portion may be achieved by making the selected portion thicker (increasing the wall thickness of the reinforced portion of the balloon). In accordance with one embodiment, the reinforcing of the selected balloon portion may be achieved by cross-linking the selected (proximal or distal) portion of the balloon to change it mechanical properties and increase the force required for causing collapse of the reinforced portion of the balloon. In accordance with yet another method of reinforcing, a reinforcing member is attached within or outside of the portion of the balloon which is to be reinforced to increase the force required for collapsing the reinforced portion of the balloon.

In accordance with one embodiment of the catheters of the present application the thickness of the wall of at least part of the proximal portion of the balloon is made thicker than the wall of the distal portion of the balloon. This thickening reinforces the proximal end such that when a force is applied to the balloon by pulling the inner tube of the catheter in the proximal direction the thicker proximal portion of the balloon will have a resistance to collapse which is significantly higher than the resistance of the thinner walled distal portion of the balloon. Thus, in the novel balloons of the catheters disclosed in the present application, the force required to initiate collapse of the proximal end of the balloon is significantly higher than the force required to initiate collapse of the distal end of the balloon. This design results in a substantial reduction in the probability of occurrence of proximal balloon end collapse relative to balloon catheters which have proximal and distal portions of the balloon having a similar wall thickness.

In accordance with another embodiment of the catheters of the present application the probability of proximal collapse of the balloons of the present application is even further reduced by providing a proper geometry to the distal and proximal end portions of the balloon. Thus, in addition for shaping the balloon to have thicker walls at the proximal end and thinner wall thickness at the distal end, the geometry of the proximal end portion of the balloon may be selected to have an improved resistance to proximal end collapse by substantially increasing the force required to cause a collapse of the proximal, while the geometry of the distal end portion of the balloon may be selected to increase the probability of distal end collapse. This combination may advantageously further increase the probability of preferential collapse of the distal end of the balloon and reduce the probability of proximal end collapse. Reference is now made to Figs 3-5. Fig. 3 is a schematic cross-sectional diagram illustrating part of an intussuscepting balloon catheter including a balloon having a proximal portion with a wall thickness greater than the wall thickness of its distal portion, in accordance with an embodiment of the catheter of the present application. The balloon catheter 20 includes an outer conduit 6 and an inner conduit 8. The outer conduit 6 is sealingly attached to the proximal end of an inflatable balloon 22 and the inner conduit 8 is sealingly attached to the distal end of the inflatable balloon 22. The proximal end and the distal end of the balloon 22 may be attached to the inner conduit 8 and the outer conduit 6, respectively by any suitable attachment method known in the art, such as, but not limited to, gluing, welding, ultrasonic welding, and the like.

It is noted that the construction, composition and operation of all of the parts of the inflatable intussuscepting balloon catheters and catheter systems disclosed in the present application has been described in detail in published International Patent Application, Publication Nos. WO 2007/004221, WO 2007/042935, WO 2008/004238 and WO 2008/004239, and are therefore not described in detail hereinafter.

The Balloon 22 includes a proximal portion 22A, a middle portion 22B and a distal portion 22C. The proximal portion 22A has a wall thickness which is larger than the wall thickness of the middle portion 22B and the distal portion 22C. In the specific schematic example of the balloon 22, the proximal portion 22A has a substantially uniform wall thickness. The wall thickness of the middle portion 22B and of the distal portion 22C is also substantially uniform but is smaller than the wall thickness of the proximal portion 22A. As found experimentally, the larger thickness of the proximal portion 22A substantially increases the force required to initiate collapse of the proximal portion 22A as compared to the force required to initiate collapse of the distal portion 22C. Thus, when the inner conduit 8 is pulled proximally within the outer conduit 6, the probability that the proximal portion 22A will collapse is greatly reduced, ensuring a very high probability that the collapse will occur only at the distal portion 22C of the balloon 22, and reducing the probability of initiation of proximal collapse as described hereinabove with respect to Fig. 2.

The balloon 22 may be made from PEBAX® (such as for example, PEBAX ^® 7233, 7033, and 6333), NYLON®, Nylon® 1 1 , Nylon® 12, PE, PET, PA12 PEBAX®, polyether block amides (PEBA), PAl 1 , PAl 2 (for example Grilamid ^® L25, L55 and the like), , PABA, , various types of Grilflex ^® (such as, for example, ELG 6260), and the like, but other suitable materials may also be used.

It is noted that while in the specific non-limiting example of Fig. 3, the proximal portion 22A has a substantially uniform wall thickness, the middle portion 22B has a substantially uniform wall thickness and the distal portion 22C has a substantially uniform wall thickness, this is not obligatory for achieving the desired reduction of the probability of proximal collapse and other types of intussuscepting balloons with portions having wall thickness gradients therealong may also be used.

Reference is now made to Fig. 4 which is a schematic cross-sectional diagram illustrating part of an intussuscepting balloon catheter including a balloon having a thick proximal portion with a non-uniform, linearly varying wall thickness, in accordance with an embodiment of the catheter of the present application. The balloon catheter 30 includes an outer conduit 6 and an inner conduit 8 as disclosed in detail hereinabove with respect to Fig. 3. The outer conduit 6 is sealingly attached to the proximal end of an inflatable balloon 32 and the inner conduit 8 is sealingly attached to the distal end of the inflatable balloon 32. The proximal end and the distal end of the balloon 32 may be attached to the inner conduit 8 and the outer conduit 6, respectively by any suitable attachment method known in the art, such as, but not limited to, gluing, welding, ultrasonic welding, and the like. The Balloon 32 includes a proximal portion 32A, a middle portion 32B and a distal portion 32C. The proximal portion 32 A has a non-uniform linearly varying wall thickness therealong. The proximal part 33A of the proximal portion 32A is thicker than the distal part 33 B of the proximal portion 32 A. The wall thickness of the proximal part 33 A is larger than the wall thickness of the distal part 33B. The wall thickness of the proximal part 33A is also larger than the wall thickness of the middle portion 32B. The wall thickness of the proximal part 33A is also larger than the wall thickness of the distal portion 32C. As illustrated in Fig. 4, the wall thickness of the proximal portion 32A decreases linearly in the direction from the proximal part 33A towards the distal part 33B.

The wall thickness of the middle portion 32B and of the distal portion 32C is substantially uniform but is smaller than the wall thickness of the proximal part 33A of the proximal portion 32A. The larger thickness of the proximal part 33A of the proximal portion 32A substantially increases the force required to initiate collapse of the proximal portion 32A as compared to the force required to initiate collapse of the distal portion 32C. Thus, when the inner conduit 8 is pulled proximally within the outer conduit 6, the probability that the proximal portion 32A will collapse is greatly reduced, ensuring a very high probability that the collapse will occur only at the distal portion 32C of the balloon 32, and reducing the probability of initiation of proximal collapse as described hereinabove with respect to Fig. 2.

It is noted that while in the specific non-limiting embodiment illustrated in Fig. 4, the wall thickness of the proximal portion 32A decreases linearly in the direction from the proximal part 33 A towards the distal part 33B, this is not obligatory and other different embodiments of the balloon and balloon catheters of the present application may be implemented by using portions having a non-linear wall thickness variation therealong (non-linear wall thickness gradient).

It is further noted that while, preferably, the length A of the proximal tapering portion 22A (of the balloon 22 of Fig. 3) is greater than the length B of the distal tapering portion 22C, this is not obligatory for the balloons of the present application. For example, in the balloon 32 of Fig. 4, the length Al of the proximal tapering portion 32A is equal to the length Bl of the distal tapering portion 32C. Thus, the selective preferential collapse of the selected balloon portion (either distal portion or the proximal portion) may be achieved by proper implementation of different wall thickness for different end portions of the balloons of the present application, in balloons having distal and proximal portions of equal length or of different length (for example, the proximal balloon portion may be longer than, equal to, and shorter than the distal portion of the balloon, depending on the specific configuration desired and on the application). Reference is now made to Fig. 5 which is a schematic cross-sectional diagram illustrating part of an intussuscepting balloon catheter including a balloon having a thick proximal portion with a non-uniform, non-linearly varying wall thickness, in accordance with another embodiment of the catheter of the present application.

The balloon catheter 40 includes an outer conduit 6 and an inner conduit 8 as disclosed in detail hereinabove with respect to Fig. 3. The outer conduit 6 is sealing Iy attached to the proximal end of an inflatable balloon 42 and the inner conduit 8 is sealingly attached to the distal end of the inflatable balloon 42. The proximal end and the distal end of the balloon 42 may be attached to the inner conduit 8 and the outer conduit 6, respectively by any suitable attachment method known in the art, such as, but not limited to, gluing, welding, ultrasonic welding, and the like. The Balloon 42 includes a proximal portion 42A, a middle portion 42B and a distal portion 42C. The proximal portion 42A has a non-uniform non-linearly varying wall thickness therealong. The proximal part 43 A of the proximal portion 42 A is thicker than the distal part 43B of the proximal portion 42A. The wall thickness of the proximal part 43A is larger than the wall thickness of the distal part 43B. The wall thickness of the proximal part 43 A is also larger than the wall thickness of the middle portion 42B. The wall thickness of the proximal part 43 A is also larger than the wall thickness of the distal portion 42C. As illustrated in Fig. 5, the wall thickness of the proximal portion 42A decreases non-linearly in the direction from the proximal part 43A towards the distal part 43B. The wall thickness of the middle portion 42B and of the distal portion 42C is substantially uniform and is smaller than the wall thickness of the proximal part 43 A of the proximal portion 42A. The larger thickness of the proximal part 43 A of the proximal portion 42A substantially increases the force required to initiate collapse of the proximal portion 42A as compared to the force required to initiate collapse of the distal portion 42C. Thus, when the inner conduit 8 is pulled proximally within the outer conduit 6, the probability that the proximal portion 42A will collapse is greatly reduced, ensuring a very high probability that the collapse will occur only at the distal portion 42C of the balloon 42, and reducing the probability of initiation of proximal collapse as described hereinabove with respect to Fig. 2. It is noted that in the specific non-limiting embodiment illustrated in Fig. 5, the wall thickness of the proximal portion 42A decreases non-linearly in the direction from the proximal part 33A towards the distal part 43B, such that the outer surface 42D of the proximal portion 42A is a conical surface and the inner surface 42E is a non-linearly curved surface ( such as, but not limited to, a surface shape formed by the rotation of a non-linearly varying curve including but not limited to a logarithmic curve, a parabolic curve, a hyperbolic curve or any other suitable non-linearly varying curve known in the art). However, this is not obligatory and other different embodiments of the balloon and balloon catheters of the present application may be implemented by using portions having other different non-linear wall thickness variation type therealong.

It will be appreciated by those skilled in the art that other different types of modifications of the wall thickness and/or shape of the proximal portions of the inflatable balloons of the catheters of the present invention may be used to increase the force required to initiate collapse of the proximal portion of the balloon. For example, in addition to the thickened walls of the proximal balloon portions disclosed in detail hereinabove (with respect to Figs. 3-5), the shape of the distal portion of the balloon may be modified to further reduce the force required for collapse of the distal portion of the balloon. Thus, all the different shapes disclosed for the proximal and/or distal portions of the intussusceptable balloons described in published International Patent applications, Publication Numbers WO 2007/004221, WO 2007/042935 incorporated herein by reference in their entirety, may be used in the intussuscepting balloons of the present application

Reference is now made to Fig. 6 which is a schematic cross-sectional diagram illustrating part of an intussuscepting balloon for use in a balloon catheter. The balloon has a non-uniform wall thickness, a truncated conical proximal portion and a partially rounded distal portion, in accordance with another embodiment of the balloon catheters of the present application.

The balloon 52 has a proximal cylindrical portion 52A having a length L4, a conical proximal portion 52B having a length L5, a middle portion 52C having a length Ll , a partially rounded distal portion 52D having a length L6 and a cylindrical distal portion 52E having a length L3 (note that L2=L5+L1+L6). The proximal cylindrical portion 52 A is attachable to an outer conduit of a catheter (such as for example the outer conduit 6 of Figs 3-5) as disclosed in detail hereinabove. The distal cylindrical portion 52E is attachable to an inner conduit of a catheter (such as for example the outer conduit 8 of Figs 3-5) as disclosed in detail hereinabove.

In accordance with one non-limiting example, L2=32.3 millimeter, L3=3 millimeter, L4= 4 millimeter, Ll= 20 millimeter, L5=9 millimeter and L6= 3.3 millimeter. The balloon 52 crossing profile is 6 French. In accordance with another non-limiting example, Ll=IOO millimeter, L2 = 1 12.3 millimeter, L3=3 millimeter, L4=4 millimeter, L 1=20 millimeter, L5=9 millimeter and L6= 3.3 millimeter. The balloon 52 crossing profile is 6 French.

However, the length, inflated diameter and other dimensions of the balloon 52 may vary and may be larger and/or smaller than the dimensions disclosed herein, depending, inter alia upon the particular application.

The proximal conical portion 52B is shaped as a truncated cone and has a cone angle α. Typically, the cone angle is in the range of α = 15° - 45° (However, this cone angle is not obligatory and other larger or smaller cone angles may also be used). The middle portion 52C is shaped as a cylindrical portion and may vary in length for different balloons. A typical range of length values for the cylindrical middle portion is 10-200 millimeters but other shorter or longer length values may also be used depending, inter alia, on the application. The distal portion 52D is typically shorter than the proximal portion 52B, but this is not obligatory. The distal portion 52D has several different contiguous parts. In the example illustrated in Fig. 6, the distal portion has three curved parts 52F, 52H and 521 and a truncated conical part 52G as illustrated in Fig. 6. The truncated conical part 52G of the distal portion 52D has a cone angle β. Typically the cone angle is in the range of β = 50° -75° (However, this cone angle is not obligatory and other larger or smaller cone angles may also be used). The part 52G is proximally flanked by the curved part 52F and distally flanked by the curved part 52H. The curved part 52H is distally flanked by the curved part 521.

In the particular non-limiting example of the balloon 52 illustrated in Fig. 6, the radius of curvature of the curved part 52F is Rl=I millimeter, the radius of curvature of the curved part 52H is R2=2.1 millimeter and radius of curvature of the curved part 521 is R 1=0.5 millimeter. It is noted that although this particular implementation of the distal part 52D was found to be satisfactory in operation, it is not obligatory. Thus, any of the parameters of the distal portion 52D including but not limited to the longitudinal length L6, the radii of curvature Rl, R2 and R3, the general shape of the distal portion, the number of curved parts included in the distal portion, and the like may be modified depending, inter alia, on the particular application and manufacturing considerations. It is noted that improved performance of the balloon catheters disclosed herein may be achieved by increasing the force required for the initiation of collapse of the proximal portion of the balloon, decreasing the force required for initiation of distal collapse and by a combination of increasing the force required for the initiation of collapse of the proximal portion of the balloon and decreasing the force required for initiation of distal collapse. This may be achieved by any desired combination of increasing the wall thickness of the proximal portion of the balloon or of at least a part thereof (such as, but not limited to the proximal portion 52B), decreasing the wall thickness of the distal portion of the balloon or of at least a part thereof (such as, but not limited to the proximal portion 52D), and using different configurations or shapes for the proximal and distal portions (as described in detail in International published application WO 2007/004221 ). Thus, all possible combinations of any of the above disclosed structural modifications of the balloon may be used in the balloon catheters disclosed in the present applications to reduce the probability of collapse of the proximal part of the balloon and/or increase the probability of collapse of the distal part of the balloon to improve catheter performance.

Typically (but not obligatorily), the balloon 52 has a crossing profile in the range of 4- 7 French and is designed for a nominal inflation pressure of 6-12 atmospheres. (However, other balloons may have different larger or smaller nominal inflation pressure values and different larger or smaller crossing profiles, depending, inter alia, on the specific application).

Typically, the wall thickness of the proximal portion 52B is approximately 0.0175 millimeter and the wall thickness of the distal part 52D is approximately 0.015 millimeter. The difference between the wall thickness of the proximal portion 52B and the distal portion 52D combined with the geometry and partially curved shape of the distal portion 52D both contribute to advantageously increasing the probability of collapse and starting of invagination of the distal portion 52D when longitudinal force is applies to the balloon in its inflated state by proximally pulling the inner conduit 8 while the outer conduit 6 remains fixed (the outer conduit 6 and the inner conduit 8 are not shown in Fig. 6 , for the sake of clarity of illustration), and greatly reduce the probability of collapse of the proximal portion 52B under the same force. It is noted that the particular shape and dimensions of the balloon 52 illustrated in Fig. 6 are given by way of example only and are not intended to be limiting. Rather, any of the dimensions and shapes or other parameters of the balloons and balloon catheters disclosed herein may be varied and modified depending, inter alia, on the particular application, as long as the proximal portion of the balloon (or at least a part thereof) has a wall thickness larger than the wall thickness of the distal portion of the balloon.

Alternatively, if the distal portion 52D of the balloon 52 and/or the proximal portion 52B do not have a uniform wall thickness (or have a wall thickness gradient therealong), the thickest part of the proximal portion 52B should be thicker than the thinnest part of the distal portion 52D. For example, if the wall thickness of the part 521 of the proximal portion 52D has a wall thickness which is smaller than the wall thickness of the parts 52F, 52G and 52H, the wall thickness of the thickest part of the proximal portion 52B should be larger than the wall thickness of the part 521 to ensure an increased probability of preferential distal portion collapse, when the inner conduit is pulled proximally within the outer conduit.

It is noted that while the structure and mode of operation of the balloon catheters using the novel balloons of the present application are not shown in detail herein, any of the catheters and methods of catheter operation disclosed in detail in Published International Patent applications, Publication Nos., WO 2007/004221 , WO 2007/042935, WO 2008/004238 and WO 2008/004239, may be used in the catheters having the balloons disclosed herein, such catheters may include but are not limited to "over the wire" type catheters (as described in detail in WO 2007/004221), "rapid exchange catheters (as described in detail in WO 2007/042935, WO 210/001404 and WO 2010/001405), catheters with collecting sheaths (as described in WO 2008/004238 and WO 2008/004239), and other types of balloon catheters having an inner conduit disposed within an outer conduit, as is known in the art.

It is noted that while the preferred embodiment of the catheters described hereinabove have thicker proximal portions to reduce the probability of collapse of the proximal portion of the balloons, the catheters of the present application also disclose balloon catheters in which the balloon is constructed to ensure the preferential collapse of the proximal portion of the balloons. Such balloons may be useful, inter alia, in cases in which the blood vessel geometry or the position of the occluded or diseased portion of the vessel may dictate preferred use a balloon which is constructed to ensure preferential collapse of the proximal balloon portion. While such proximally collapsing balloons may still having the same problem of a possible snagging of the proximal infolding during withdrawal of the intussuscepted balloon through the guiding catheter or introducing sheath, this problem may be solved by using a snaring device or loop (as is known in the art) to encircle the proximal end of the intussuscepted balloon and to constrict it and prevent or reduce the possibility of snagging during withdrawal of the balloon from the body. Reference is now made to Fig. 7 which is a schematic cross-sectional diagram illustrating part of an intussuscepting balloon catheter including a balloon having a distal portion with a wall thickness greater than the wall thickness of its proximal portion, in accordance with another different embodiment of the catheter of the present application.

The balloon catheter 60 includes an outer conduit 6 and an inner conduit 8 (as described in detail for the catheter 20 of Fig. 3). The outer conduit 6 is sealingly attached to the proximal end of an inflatable balloon 62 and the inner conduit 8 is sealingly attached to the distal end of the inflatable balloon 62. The proximal end and the distal end of the balloon 62 may be attached to the inner conduit 8 and the outer conduit 6, respectively by any suitable attachment method known in the art, such as, but not limited to, gluing, welding, ultrasonic welding, and the like.

It is noted that the construction, composition and operation of all of the parts of the inflatable intussuscepting balloon catheters and catheter systems disclosed in the present application has been described in detail in published International Patent Application, Publication Nos. WO 2007/004221, WO 2007/042935, WO 2008/004238 and WO 2008/004239, WO 210/001404 and WO 2010/001405 , and are therefore not described in detail hereinafter.

The Balloon 62 includes a proximal portion 62A, a middle portion 62B and a distal portion 22C. The distal portion 62C has a wall thickness which is larger than the wall thickness of the middle portion 62B and the proximal portion 62A. In the specific schematic example of the balloon 62, the proximal portion 62A may have a substantially uniform wall thickness. The wall thickness of the middle portion 62B and of the proximal portion 22A may or may not be substantially uniform (such as the non uniform gradually proximally thinning wall thickness in the distal part 62D of the middle portion 62B , in the specific example illustrated in Fig. 7). The average wall thickness of most of the middle portion 62B and the proximal portion 62A is smaller than the wall thickness of the proximal portion 62A. As found experimentally (see details of experiments in hereinbelow), the larger thickness of the distal portion 62A substantially increases the force required to initiate collapse of the distal portion 62C as compared to the force required to initiate collapse of the proximal portion 62A. Thus, when the inner conduit 8 is pulled proximally within the outer conduit 6, the probability that the proximal portion 62 A will collapse is substantially increased, ensuring a high probability that the collapse will occur only at the proximal portion 62A of the balloon 62, and substantially reducing the probability of initiation of distal collapse as described hereinabove with respect to Fig. 2. The shape of a balloon after preferential proximal collapse (due to special geometrical balloon shaping of the balloon ends but not due to differences in balloon wall thickness as disclosed herein) is illustrated and explained in PCT publication WO 2007/042935 ( in Fig. I E thereof) and is therefore not discussed in detail hereinafter.

It is noted that while in the specific non-limiting example of Fig. 7, most of the proximal portion 62A and most of the middle portion 62B have a substantially uniform wall thickness, this is not obligatory for achieving the desired reduction of the probability of distal collapse and other types of intussusceptable balloons with portions having wall thickness gradients therealong may also be used as long as the wall thickness of at least part of the distal portion 62C is substantially thicker than the maximal wall thickness of the proximal portion 62A.

It is noted that while the balloons described hereinabove achieve high probability of collapse of their distal portion (Figs. 3, 4, 5, 6, 8, 9, 1 1 and 16) or their proximal portion (Fig. 7), the present application discloses other different types of balloons and catheters having a preferential tendency of collapse of their distal or proximal portions (as desired) by reinforcing either the proximal or the distal balloon portions, respectively.

Reference is now made to Fig. 8 which is a schematic cross-sectional diagram illustrating part of an intussuscepting balloon catheter including a balloon having a reinforced proximal portion, in accordance with an embodiment of the catheter of the present application.

The catheter 70 has an inner tube 8 and an outer tube 6 as disclosed in detail hereinabove with respect to catheter 20 of Fig. 3. The balloon 72 has a proximal part 72 A a middle part 72B and a distal part 72C. In contrast to the balloon 22 of Fig. 3 which has a non uniform wall thickness along its different portions, the balloon 72 has a substantially uniform wall thickness along its length. However, the balloon 72 includes a reinforcing member 72R therewithin. The reinforcing member 72R is shaped as a axially symmetric part cylindrical part conical tube attached within the balloon as illustrated in Fig. 8. The reinforcing member may be made from the same material as the material forming the balloon 72 such as, but not limited to, PEBAX® (such as for example, PEBAX ^® 7233, 7033, and 6333), NYLON®, Nylon® 1 1, Nylon® 12, PE, PET, PAl 2 PEBAX®, PEBA, PAl 1, PA 12 (for example Grilamid ^® L25, L55 and the like), PABA, Polyether block amides, various types of Grilfiex ^® (such as, for example, ELG 6260), and the like. However, the reinforcing member may be made from a material different than the material from which the balloon 72 is made. The balloon 72 is attached to the inner tube 8 and to the outer tube 6 as disclosed in detail hereinabove. For example, the balloon 72 may be made from PEBAX ^® 7233 and the reinforcing member 72R may be made from PEBAX ^® 7033. The reinforcing member 72R may be attached to the balloon 72 by any suitable method such as gluing, welding, thermal bonding, ultrasonic welding and the like. However, the reinforcing member 72R may be formed as a short sleeve or cylinder (not shown) inserted into the raw cylindrical tubing used to form the balloon 72. When the raw tubing is processed by blow molding to form the balloon 72, the short cylindrical tubing is formed into the reinforcing member 72R as illustrated in Fig. 8) by the heat and pressure used in the molding process. The heating and/or internal pressure applied during the blow molding process may also attach the reinforcing member to the walls of the balloon 72.

In operation, when the balloon 72 is inflated and the inner tube 8 is moved proximally within the outer tube 6, the longitudinal axial force required to collapse the distal portion 72C will be substantially smaller than the force required to collapse the proximal portion 72A, due to the reinforcing action of the reinforcing member 72R. As a result, the probability of collapsing of the distal portion of the balloon during proximal movement of the inner tube 8 is substantially increased. As previously described, the shape and relative length of the parts 72A, 72B and 72C may be modified as desired to even further increase the probability of distal collapse.

It will be appreciated that, in accordance with another embodiment of the catheters of the present application, if a balloon with increased probability of the proximal portion collapse is desired, this may be achieved by attaching a reinforcing member (not shown) within the distal portion 72C of the balloon in a way similar to the attaching of the proximal reinforcing member 72R within the proximal portion 72 A. The distal reinforcing member may be shaped to match the internal shape of the distal portion 72C but the principles of attaching are identical to those described. In such a catheter, the proximal side of the balloon will preferentially collapse when the inner conduit 8 is proximally moved within the outer conduit 6. In accordance with yet another different embodiment of the catheters of the present invention, the reinforcing of either the proximal portion or the distal portion (depending on where the collapsing is preferred) of the balloon may also be achieved also in a balloon having a substantially uniform wall thickness along its length and without using any reinforcing member. In accordance with this embodiment, the reinforcing of the selected balloon portion is performed by selectively changing the mechanical properties of the material forming the balloon walls at the desired balloon portion.

For example, it is possible to selectively reinforce a portion of the balloon for increasing its resistance to buckling or collapsing in response to longitudinal forces acting thereupon by cross-linking the material in the desired balloon portion as is known in the art. In a non-limiting example, the balloon has a uniform wall thickness and is made from polyethylene (PE). The balloon may be shaped by blow-molding, as is known in the art. The balloon may be subjected to electron beam cross-linking, either before or after the blow molding to cross link the PE in the desired balloon portion (such as, for example by using suitable steel masks or other electron beam opaque masks to block the electron beam from reaching selected parts of the balloon as is known in the art). Thus, when the proximal portion of a balloon is cross-linked changing its mechanical compliance properties, the treated proximal portion will have larger resistance for collapsing forces and the distal (non-cross-linked) portion will preferentially collapse during application of a proximally directed axial force to the balloon. Alternatively, when the distal portion of a balloon is cross-linked changing its mechanical compliance properties, the treated distal portion will have larger resistance for collapsing forces and the proximal (non-cross- linked) portion will preferentially collapse during application of a proximally directed axial force acting to the balloon.

Furthermore such cross-linking or other chemical, electromagnetic radiation induced, or particle beam induced changes in the mechanical properties of part of the balloon may be effected not only by electron beam based methods but also by chemically induced cross-linking, UV irradiation induced cross-linking or by any other method known in the art for modification of the mechanical properties of a material usable in making balloons suitable for use in balloon catheters.

Additional methods for making balloons having differential mechanical properties at different parts thereof are disclosed in US published application number 2003/002821 1 to Crocker et al., incorporated herein by reference in its entirety, and are therefore not disclosed in detail hereinafter. All such methods are usable in making the balloons of the present application.

Experiments for quantitatively studying the effects of balloon wall thickness on the force of collapse of various different balloon portions were performed on selected shapes on dimensions of balloons as follows. While, these experiments were carried out on a limited number of balloons having particular shapes and dimensions, they provide some practical examples and insight on the parameters involved in collapse of different balloon portion while not intended to be limiting in any way and the materials used, the balloon dimensions and the balloon shapes may be varied and changed when implementing the balloon catheters of the present, depending, inter alia, on the particular applications and various manufacturing and design considerations.

The balloons disclosed hereinabove may be made by using blow-molding procedures as is known in the art. Briefly, thermoplastic tubing made from Pebax 7233 has been used in the experiments. Tubing segments were processed into parisons by heating and pulling the tubing segments using standard techniques. The parison was then blow molded in a suitable mold and the pulling force of the necks of the parison (while the parison was pressurized as is known in the art), and the position of the parison within the mold were controlled to achieve the desired wall thickness distribution in the resulting balloon. The difference in wall thickness between the proximal portion and the distal portion of the balloon were a result of an asymmetric longitudinal placement of the parison within the mold, such that the portion of the parison which was closer to one side of the mold was subjected to lesser longitudinal stretching, resulting is a smaller wall thinning of this portion than the wall thinning of the parison portion which was positioned at a longer distance from the mold's opposite end. Several experiments were performed for testing the collapse forces of balloons having differential wall thickness as disclosed hereinabove and the results of increasing the wall thickness of the proximal portion of the balloons on the forces required to initiate collapse of the distal and proximal portions of the balloons. While the experiments disclosed below, are for specific balloon shapes and dimensions, this is not intended to limit the scope of the balloons, balloon catheters and balloon catheter systems of the present application and are given by way of example only. All the balloon and catheter's parameters including but not limited to balloon wall thickness, wall thickness distribution along the balloons, balloon shape, balloon dimensions, and the longitudinal dimensions of the proximal, distal and middle portions of a balloon, may be varied and modified, depending, inter alia, on the specific application, and design and manufacturing considerations.

The force required to collapse the proximal and distal cones of various balloon sizes as a function of measured balloon wall thickness at the cones themselves and throughout the cylindrical body was experimentally determined. The proximal and distal cones of the balloon were distinctly different from each other in shape and function, the former being designed to resist collapse and the latter having collapse and inversion as part of its functionality, the effect of any taper in the balloon cylinder wall was assessed. Such non- uniformities can occur during the rapid initial inflation of a balloon during blow-molding, especially for balloons with a large aspect ratio (i.e. balloon length » balloon diameter). The balloons measured were 4x100mm balloons (balloon diameter X balloon length).

The balloons were measured using an optical technique to obtain single wall thickness (SWT) at several points along the balloon. After dimensional data was collected, the buckling force of the unsupported balloon cones was measured. Each balloon was tested as a single piece and five (5) samples were tested. The balloons were blow molded from a single Pebax 7233 tubing lot (WO 23591) extruded at Interface Associates, USA. A Shimadzu AGS-J Universal Testing Machine (UTM) configured with 5ON load cell was used in the collapse force measurements. Optical measurements of balloon wall thickness were performed using a Lumetrics™ "Opti-Gage" non-contact optical measurement device with a rotational module. The balloons were tested within a suitable containment cylinder. A Pressure Tester model PT 500 or PT 1000 was used and a Tuohy-Burst Fixture was used for attaching the pressure tester to the balloon. Mandrels with an outer diameter OD=0.036 inch were used to fit ID of proximal and distal balloon necks to transmit the force from the UTM to the cones. A UV curable or an atmospheric curing adhesive was applied to pins or mandrels prior to insertion into the balloon necks.

Reference is now made to Fig. 9 which is a schematic diagram illustrating reference points used in measuring the distances of points at which wall thickness was experimentally determined for a series of balloons manufactured with non-uniform wall thickness, in accordance with an embodiment of the balloons of the present application. It is noted that the distal and proximal portions of the tested balloons are also referred to as the balloon cones in the description of the experiments hereinafter. Using the Lumetrics™ Opti-Gage and a rotational fixture (not shown) each balloon was measured for wall thickness in inches at eleven positions on the cylindrical body represented in Fig. 9 by the cross-sections A-A, B-B, D-D, E-E, F-F, G-G, H-H, I-I, J-J, K-K, and L-L) of the balloon 1 10. The position of each measurement on the balloon 1 10 is shown in TABLE 1 below as an absolute distance (in millimeter) from one of four reference points corresponding to transitions in the balloon 1 10. The reference points are represented by the arrows 1, 2, 3 and 4 in Fig. 9. The positioning was achieved via a micrometer slide built into the fixture. First the cylindrical portions of the balloon 1 10 were measured (the necks and body of the balloon at cross sections A-A, F-F, G-G and H-H). The measurements consisted of two single wall thickness (SWT) measurements based on light reflection from the top and bottom surfaces of the wall. The balloon was rotated so that the two SWT measurements are gathered at 0° and 180° around the balloon's circumference. The balloon 1 10 was then positioned to measure the cones. The balloon fixture (not shown) was rotated to set the value for each cone half angle and then the cones were measured (at the points of sections B-B, D-D, E-E and I-I, J-J and K-K). Each measurement in the conical section gave only one of the two wall thickness measurements required since the far side reflection of the measuring beam was lost. Thus the balloon was rotated on its long axis by 180° steps and a second measurement was recorded for the wall thickness of the cone.

TABLE 1

In TABLE 1, the numbers represent the measured distance (in millimeter) between the cross section and the relevant reference point (selected from reference points 1, 2, 3 and 4 of Fig. 9).

Reference is now made to Fig. 10 which is a schematic cross-sectional diagram illustrating part of the experimental apparatus used for determining the force of collapse of distal and/or proximal balloon portions (also referred to as the Balloon cones hereinafter) in experiments described hereinbelow. Compressive Force Recording was done by using the A Shimadzu AGS-J Universal Testing Machine (UTM). The UTM was configured such that the 50N load cell was installed and the rubber coated clamp faces were removed from the lower pneumatic clamp. The extensometer of the UTM was deactivated. A mandrel 95 (having a 0.036 inch outer diameter) attached to the cross- head 100 was inserted into the balloon neck 9ON nearest the cone to be measured and glued in place. The tested balloon 90 was loaded in a Perspex® cylindrical fixture 94 with the cone 9OA to be measured uppermost. The tubing on the opposite cone 9OC was connected to the pressure tester via a Tuohy-Burst fitting 97. The balloon 90 was then pressurized to 1.5 Atm with distilled water and care was taken to eliminate any air bubbles.

The vertical position of the balloon was adjusted so that the body to cone transition was level with the top of the cylindrical fixture 94. The cross head 100 of the UTM was lowered into position using the up and down arrows on the front panel of the UTM. Then the position reading and the force reading was set to zero. Finally the upper pneumatic clamp (not shown) was closed on the mandrel 95. The testing program specifying the speed (100 mm/min) of the cross head 100 and the extent of travel of the cross-head 100 (equal to the cone height of the balloon) was then loaded. The direction of movement of the cross-head 100 is schematically represented by the arrows 93. Once initiated, the test recorded force and position data. The Maximum Force (N) was the parameter of primary interest and was captured as part of the program's data analysis feature. It is noted that preliminary work had indicated that no useftil data could be gained by repeating the measurement in the same tested balloon since the value of the maximum force was always reduced compared to the first run, indicating a permanent crease had been introduced into the balloon skin. The recorded data was analyzed to compute mean and standard deviation of the recorded maximum force as a function of cone wall thickness.

Reference is now made to Fig. 1 1 which is a schematic diagram, illustrating a side view of a typical balloon having a non-uniform wall thickness therealong used in the experiments and cross-sectional views taken at various positions therealong. The balloon 1 10 (also illustrated in Fig. 9 hereinabove) is illustrated together with cross sections thereof along the lines A-A, B-B, D-D, E-E, F-F, G-G, H-H, I-I, J-J, K-K, and L-L.

Reference is now made to Fig. 12 which is a schematic bar graph, illustrating the wall thickness of the balloon 1 10 of Fig. 1 1 as measured at the cross-sections A-A to L-L of Fig. 1 1. This bar-graph shows the mean value for each wall thickness measurement taken at two radial positions: 0° and 180°. The error bars represent one standard deviation of the mean. In Fig. 12, the vertical axis represents the thickness of the wall ( in inches) at the measurement point and the horizontal axis represents the position of the measurement points. For each bar, the height of the bar represents the computed mean thickness measured and the characters underneath each bar (selected from A, B, C, D, E, F, G, H, I, J, K, and L) represent the position of the measurements ( as performed at the position represented by the cross-section lines A-A, B-B, D-D, E-E, F-F, G-G, H-H, I-I, J-J, K- K, and L-L, respectively.

As can be seen in the graph of Fig. 12, the mean wall thickness values follow a similar pattern to the data obtained from 6x100 balloons (balloons having a crossing diameter of 6mm and a length of 100mm). The main difference is in the absolute values since the tubing used for the 4x100 (balloons having a crossing diameter of 4 mm and a length of

100mm) balloons is thinner walled.

Some of the data show large standard deviations. This may be explained by irregularities in the cone wall due to incomplete cone expansion during the inflation process. These features are often called "crows' feet" and may be cosmetically undesirable when considering a conventional angioplasty balloon. However, in the balloons of the present application, such irregularities bring an unexpected benefit by acting as "stiffening rods" in the cone.

Typically, the difference between the mean wall thickness values taken at cross sections B-B ( mean value of 0.0024 inch) and K-K (mean value of 0.0021), is 0.0003 inch. This demonstrates that on the average, the wall thickness at the section B-B (which is the measurement position closest to the inflatable end of the proximal portion of the balloon 1 10) is thicker by about 14% than the wall thickness at the section K-K (which is the measurement position closest to the inflatable end of the distal portion of the balloon 1 10).

Reference is now made to Fig. 13 which is a schematic bar-graph, illustrating the mean force required for collapsing the proximal cone and distal cone of a typical balloon, constructed in accordance with an embodiment of the present application. The results were obtained from performing collapse measurement on the same batch of five balloons tested for wall thickness as disclosed hereinabove and illustrated in Fig. 12. In the bar graph of Fig. 13, the vertical axis represents the collapse force of the proximal and distal portions (the proximal and distal cones) of the tested balloons. The height of the bar 120 represents the mean collapse force of five proximal cones of the tested balloons and the bar 130 represents the mean collapse force of five distal cones of the same tested balloons. Each data point comes from analyzing the output graph from the tensile tester of the UTM and assigning the maximum force value. The first 3mm of displacement are the key to the initiation of cone collapse and so the maximum value of force is taken within the first 1-2 mm of travel. During testing of each balloon, as the test proceeds beyond the first 3mm travel, higher forces may be seen due to other phenomena, unrelated to the cone collapse itself.

The numerical measurement results for the five tested balloons are given in TABLE 2.

TABLE 2

From the results of Table 21 as illustrated in Fig. 13, it is concluded that the cone collapse force for the proximal cone is significantly greater than for the distal cone. The force values are separated by slightly more than one standard deviation so are likely to be significantly different statistically.

In order to determine the dependence of the collapse force on the balloon wall thickness, data was compared from the two balloon sizes used in the testing (4 x 100 and 6 x 100 mm).

Reference is now made to Fig. 14 which is a schematic graph, illustrating the dependence of the mean force required for proximal cone collapse on the mean single wall thickness of the balloon at the cross-section B-B of Fig. 1 1. In Fig. 14, the vertical axis represents the force (in Newton) required for collapsing the proximal cone of the balloon 1 10. and the horizontal axis represents the mean wall thickness (in inch) of the balloon cones as determined for the measurement points represented by section lines B-B. The hollow rhombus-like symbols each represent the mean proximal cone collapse force determined from measurements performed in 5 balloons of the same dimensions. The symbol 141 represents the mean proximal cone collapse force determined from measurements performed in 5 balloons having a diameter of 4mm and a length of 100mm, while the symbols 142, 143 and 144 represent the mean proximal cone collapse force determined from measurements performed in 5 balloons having a diameter of 6 mm and a length of 100mm. Each of the mean data point represented by the symbols 142, 143 and 144, was determined for a batch of 6x100 balloons made from a different tubing lot having a different raw tubing wall thickness. Thus, the five balloons made from each of the different tubing lots had a different wall thickness as measured at the section lines B- B.

The straight line 150 represents a curve fit to all the data points by using standard linear regression curve fitting. The resulting straight line 150 may be extrapolated back to the origin as indicated by the dashed line 151. The calculated correlation coefficient (R ² = 0.961) is quite high, indicating a significant relationship between the data points.

When the properties of the raw tubing used to prepare the balloons were examined they reveal a correlation of the raw tubing wall thickness and the collapse force of the cones of the balloons made from the raw tubing.

Reference is now made to Fig. 15 which is a schematic graph, illustrating the dependence of the mean force required for proximal cone collapse on the mean wall thickness of the raw tubing used for blow- molding of the balloons. In Fig. 15, the vertical axis of the graph represents the mean proximal cone collapse force (in Newton) as computed for the different balloons and the horizontal axis represents the wall thickness (in inches) of the raw tubing from which each batch of balloons were made. The hollow rhomboidal symbols represent mean data values for all tubing batches (including in-house made tubing and tubing outsourced from Interface Associates, USA) while the hollow square symbols represent mean data taken only from tubing obtained from

Interface Associates, USA (outsourced tubing). The leftmost rhombus symbol and square symbol represent mean data taken from measurements made in balloons having a diameter of 4 mm and a length of 100mm (4x100 balloons), while the remaining symbols

(both square symbols and rhombus symbols) represent mean data points taken from measurements made in balloons having a diameter of 6 mm and a length of 100 mm (6x100 balloons). It is noted that for raw tubing having a mean tubing diameter of 0.013 inch, only one point is available for the 6X100 balloons made from tubing outsourced from Interface Associates, USA. The straight line 160 (calculated by a standard linear curve fitting program), shows the interdependence of the cone collapse force for the proximal cone and the mean wall thickness of the original tubing used to blow-mold the balloons. The correlation is especially good correlation coefficient (R ² = 0.9914) if the tubing made in-house under controlled extrusion conditions is considered and the outsourced tubing excluded from the data taken for curve fitting. The line 160 does not intercept the origin.

To summarize the results of the experiments, a single balloon lot (4x100 mm) was examined by dimensional measurement and by cone collapse force measurement. Comparing the data with previous work for a second balloon size (6x100 mm), a clear correlation was seen between the balloon proximal cone wall thickness (measured close to the neck) and its measured collapse force. Assuming a low cone collapse force at the proximal end of a balloon is considered undesirable, it is clear that resistance to collapse can be ensured by maximizing the balloon cone wall thickness during the blow molding process. This process in turn can be optimized by using balloon tubing with a thicker wall, as seen in the tubing lots outsourced from Interface Associates. However, in accordance with other embodiments of the catheters, it may be desired to construct balloons having preferred proximal collapse which may be implemented as shown in Fig. 7 hereinabove.

Reference is now made to Fig. 16 which is a schematic cross-sectional diagram illustrating part of an intussusceptable balloon catheter including a balloon with a reinforced proximal portion, in accordance with an embodiment of the catheter of the present application.

The catheter 80 includes the inner tube 8 and an outer tube 6 as disclosed in detail hereinabove with respect to catheter 20 of Fig. 3. The catheter 80 also includes the balloon 72 having a proximal part 72A a middle part 72B and a distal part 72C, and having substantially uniform wall thickness along its length a as disclosed in detail with respect to Fig. 8. The catheter 80 also includes a reinforcing member 72S. The reinforcing member 82S is shaped as an axially symmetric, part cylindrical part conical tube attached outside of the balloon 72 as illustrated in Fig. 16. The reinforcing member 82S may be made from the same material as the material forming the balloon 72 such as, but not limited to, PEBAX® (such as for example, PEBAX ^® 7233, 7033, and 6333), NYLON®, Nylon® 1 1, Nylon® 12, PE, PET, PA12 PEBAX®, PEBA, PAl 1, PA12 (for example Grilamid ^® L25, L55 and the like), PABA, Polyether block amides, various types of Grilflex ^® (such as, for example, ELG 6260), and the like. However, the reinforcing member 82S may be made from a material different than the material from which the balloon 72 is made. The balloon 72 is attached to the inner tube 8 and to the outer tube 6 as disclosed in detail hereinabove. For example, the balloon 72 may be made from PEBAX ^® 7233 and the reinforcing member 82S may be made from PEBAX ^® 7033.

The reinforcing member 82S may be attached to the outer surface of the balloon 72 by any suitable method such as gluing, welding, thermal bonding, ultrasonic welding and the like. However, the reinforcing member 82S may be formed as a short sleeve or cylinder disposed over the raw cylindrical tubing used to form the balloon 72. When the raw tubing is processed by blow molding to form the balloon 72, the short cylindrical tubing is formed into the reinforcing member 82S as illustrated in Fig. 16) by the heat and pressure used in the molding process. The heating and/or internal pressure applied during the blow molding process may also attach the reinforcing member 82S to the walls of the balloon 72. In operation, when the balloon 72 of the catheter 80 is inflated and the inner tube 8 is moved proximally within the outer tube 6, the longitudinal axial force required to collapse the distal portion 72C will be substantially smaller than the force required to collapse the proximal portion 72 A, due to the reinforcing action of the reinforcing member 82 S. As a result the probability of collapsing of the distal portion of the balloon during proximal movement of the inner tube 8 is substantially increased. As previously described, the shape and relative length of the parts 72A, 72B and 72C may be modified as desired to even further increase the probability of distal collapse.

It will be appreciated that, in accordance with another embodiment of the catheters of the present application, if a balloon with increased probability of the proximal portion collapse is desired, this may be achieved by attaching a reinforcing member (not shown) to the external surface of the distal portion 72C of the balloon in a way similar to the attaching of the proximal reinforcing member 82S to the external surface of the proximal portion 72A of the catheter 80. The distal reinforcing member may be shaped to match the internal shape of the distal portion 72C but the principles of attaching are identical to those described. In such a catheter, the proximal side of the balloon will preferentially collapse when the inner conduit 8 is proximally moved within the outer conduit 6.

It will be appreciated by those skilled in the art that all the above disclosed methods of reinforcing disclosed hereinabove may be applied to construct balloons with a preference for either distal or proximal collapse, depending inter alia on the application.

It is noted that in accordance with embodiments of the balloons of the present application, the distal portion and/or the proximal portion of the balloon, may have a shape selected from a tapered portion with a rounded extremity, a dome-like portion, a truncated dome-like portion, a conical portion, a frusto-conical portion, a corrugated dome-like portion, a corrugated conical portion, a corrugated frusto-conical portion, and a corrugated truncated dome-like portion. Such shaped are described in detail in Publications WO 2005/102184, WO 2007/004221 , WO 2007/042935, WO 2008/004238, WO 2008/004239, WO 210/001404 and WO 2010/001405. The reinforced distal and/or proximal portions of the balloons disclosed herein may have (but are not limited to) any of the above shapes or any of their combinations.

It is further noted that in accordance with embodiments of the balloons of the present application, the reinforced balloons disclosed herein may be used in any type of over the wire or rapid exchange catheter having an outer conduit and an inner conduit having at least one movable part. Such catheters include, but are not limited to, any of the catheters described in detail in Publications WO 2007/004221, WO 2007/042935, WO 2008/004238, WO 2008/004239, WO 210/001404 and WO 2010/001405. It is further noted that in accordance with embodiments of the catheters of the present application, the catheters disclosed herein may include therein any type of the pressure regulating mechanisms disclosed in detail in Publications WO 2007/004221 , WO 2007/042935, WO 2008/004238, WO 2008/004239, WO 210/001404 and WO 2010/001405. Such pressure regulating mechanisms may include, inter alia, a pressure regulating mechanism including a syringe-like structure disposed at the proximal end the catheter. The syringe-like structure includes a piston-like member. The syringe-like structure is in fluidic communication with the internal space within the catheter and the balloon. The piston like member is movably disposed within the syringe-like structure and is mechanically coupled to the moving mechanism of the movable part of the inner conduit. When the movable part of the inner conduit is moved proximally, the amount of inflation fluid ejected from the balloon during the intussuscepting is accommodated within the syringe-like structure. This mechanism is disclosed in detail in WO 2007/004221, WO 2007/042935, WO 2008/004238, WO 2008/004239, WO 210/001404 and WO 2010/001405, and is therefore not described in detail.

Another type of pressure regulating mechanism which may be included in embodiments of the catheters of the present application includes an outlet in fluidic communication with the lumen of the inflatable balloon (through the outer conduit). The outlet has an opening and a compliant member sealingly attached to the opening for at least partially relieving over-pressure in the lumen of the catheter and of the balloon

Another type of pressure regulating mechanism which may be included in embodiments of the catheters of the present application includes an over-pressure valve outlet (not shown) formed in the outer conduit of the catheter which is in fluidic communication with the lumen of the inflatable balloon and an over-pressure valve (not shown) disposed within the over-pressure outlet to allow discharging of fluid from the lumen of the catheter and from the balloon when over-pressure conditions develop in the lumen or in the balloon.

Another type of pressure regulating mechanism which may be included in embodiments of the catheters of the present application includes an expandable or inflatable portion of the outer conduit (not shown), capable of expanding when overpressure conditions occur in the lumen of the balloon to at least partially relieve the over- pressure in the lumen of the catheter and of the balloon.

Another type of pressure regulating mechanism which may be included in embodiments of the catheters of the present application includes a hydraulic accumulator (not shown). The hydraulic accumulator may be controllably fluidically connected and disconnected from the space in the lumen of the catheter and in the lumen of the balloon. The hydraulic accumulator regulates the pressure within the catheter's lumen and of the balloon All of the above described pressure regulating mechanisms are disclosed in detail in WO 2007/004221, WO 2007/042935, WO 2008/004238, WO 2008/004239, WO 210/001404 and WO 2010/001405, and are therefore not described in detail herein.