Balloon catheters

Catheters or other tubular devices and methods for using them to perform a medical procedure are provided. In an exemplary embodiment, a tubular device includes an elongate tubular member comprising a proximal end, a distal end sized for introduction into a patient's body, and a lumen extending between the proximal and distal ends; an expandable member on the distal end comprising an outer impermeable membrane with an inner surface surrounding a substantially enclosed interior space; and a fiber network within the interior space coupled to the inner surface and configured to limit expansion of the membrane when inflation media is directed into the interior space from the lumen to expand the membrane to an expanded configuration.

FIELD OF THE INVENTION

The present invention relates to catheters and to methods for making and using catheters. More particularly, the present invention relates to catheters including balloons with internal supports and/or that otherwise expand to non-circular profiles, and to methods for making and using catheters including such balloons.

BACKGROUND

Balloons are good at providing substantially uniform forces to the walls of a body lumen because most such lumens have a circular cross-sectional profile, as do most balloons. Indeed, it is difficult to create a balloon that, upon inflation, assumes other shapes other than cylindrical shapes with circular cross-sectional profiles since such a shape generally minimizes wall tension by maximizing the ratio of volume to surface area.

A balloon's tendency to adopt a circular profile becomes a problem when the balloon is being used to apply force to a non-circular surface. Pressure is applied uniformly only when the shape of the impacted surface matches the shape of the balloon (i.e., circular). Many compressive applications, outside the bounds of a body lumen, call for balloons of fixed, non-circular, inflated shape.

Accordingly, balloons that may be expanded to non-circular profiles would be useful.

SUMMARY

The present invention is directed to catheters and to methods for making and using catheters. More particularly, the present invention is directed to catheters including balloons with internal supports and/or that otherwise expand to non-circular profiles, and to methods for making and using catheters including such balloons.

There are several ways to impose a non-circular profile on an inflated balloon by placing rigid elements in its wall, but these elements are not easily compressed into a low-profile configuration for atraumatic insertion.

An alternative approach employs multiple balloons, each of which assumes a circular cross-sectional profile when inflated, while the combined multi-balloon structure may have a different shape. However, the surface of the balloon will inevitably have a bumpy surface reflecting the curvature of individual balloons. Increasing the number of constituent balloons reduces the bumpiness, but increases the bulk.

Besides, the walls of all of the internal balloons serve only to constrain the outward movement of the balloons in the surface layer: a function that can be performed equally well by an internal network of fibers. The network of fibers can take many forms, since it serves only to resist the outward expansion of the balloon envelope. If the fibers are substantially inelastic and interconnected, the maximally expanded shape of the fiber mass becomes the maximally expanded shape of the balloon envelope that is securely glued to its outer surface. In an exemplary embodiment, the fiber mass may resemble a sponge, or a scrubbing pad, made of interconnected strands of flexible polymer or flexible metal wire.

In accordance with an exemplary embodiment, a tubular device is provided for performing a medical procedure that includes an elongate tubular member comprising a proximal end, a distal end sized for introduction into a patient's body, and a lumen extending between the proximal and distal ends; an expandable member on the distal end comprising an outer impermeable membrane with an inner surface surrounding a substantially enclosed interior space; and a fiber network within the interior space coupled to the inner surface and configured to limit expansion of the membrane when inflation media is directed into the interior space from the lumen to expand the membrane to an expanded configuration.

In accordance with another embodiment, a method is provided for performing a medical procedure within a patient's body that includes providing an expandable member on a distal end of a tubular device, the expandable member comprising an outer membrane with an inner surface surrounding a substantially enclosed interior space and a fiber network within the interior space coupled to the inner surface; compressing the expandable member to a compressed configuration; introducing the distal end with the expandable member in the compressed configuration into a patient's body; positioning the expandable member adjacent a body structure within the patient's body; and expanding the expandable member to an expanded configuration to contact the body structure, the fiber network limiting expansion of the membrane.

Other aspects and features including the need for and use of the present invention will become apparent from consideration of the following description taken in conjunction with the accompanying drawings.

DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENTS

Turning to the drawings,FIG. 1shows an exemplary embodiment of a catheter8including a tubular member or body10and a balloon20carried thereon. As described further elsewhere herein, the balloon20generally includes an internal network of fibers30(e.g., as shown inFIGS. 2A-2D) that limit expansion of the balloon20in a predetermined manner, e.g., to cause the balloon20to expand into a non-circular or non-cylindrical shape, such as a rectangular or other shape defining one or more substantially planar walls.

Generally, the tubular member10includes a includes a proximal end12, e.g., including a handle or hub50, a distal end14sized and/or shaped for introduction into a patient's body, and one or more lumens16extending therebetween, thereby generally defining a longitudinal axis18. For example, an inflation lumen16amay be provided that extends from a side port52aon the hub50to communicate between a source of inflation media, e.g., a syringe (filled with inflation gas or fluid, such as saline, not shown) and an interior of the balloon20. Optionally, one or more additional lumens may be provided, e.g., a guidewire or instrument lumen extending between a port52bon the proximal end and an outlet17on the distal end14(not shown).

In one embodiment the catheter8may have a substantially homogenous construction between the proximal and distal ends12,14. Alternatively, the construction may vary along the length of the catheter8to provide desired properties. For example, a proximal portion of the tubular member10adjacent the proximal end12may be substantially rigid or semi-rigid, e.g., providing sufficient column strength to allow the distal end14of the catheter8to be pushed or otherwise manipulated from the proximal end12, while the distal portion24may be substantially flexible.

As shown inFIG. 1, the balloon20may be mounted around the distal end14, e.g., such that the tubular member10terminates in a tapered and/or otherwise atraumatic distal tip15. Alternatively, the balloon20may be mounted to the distal tip such that the balloon20extends partially or entirely distally beyond the distal end14, e.g., similar to the embodiment shown inFIGS. 2A-2D.

FIGS. 2A-2Dshow an exemplary embodiment of a balloon20that includes an outer balloon membrane22and an internal supporting structure, e.g., a fiber network30including a plurality of fibers32. The membrane22generally includes inner surfaces24and outer surfaces26and defines a substantially enclosed interior space28. Generally, the balloon20is expandable between a compressed or delivery configuration (e.g., as shown inFIGS. 2C and 2D), and an expanded configuration (e.g., as shown inFIGS. 2A and 2B).

The fiber network30is configured to limit expansion and/or deformation of the membrane22, e.g., to configure the balloon20in a predetermined shape when expanded. For example, fibers32may be formed from substantially inelastic materials and their lengths may be set to subject the fibers32to tension when the balloon is expanded to the expanded configuration. The fiber network30may limit balloon expansion most in any direction that is substantially parallel to the preponderant direction of the fibers32.

For example, as shown inFIG. 2B, the fibers32extend from a first inner surface24aacross the interior space28to a second opposite inner surface24b. In this manner, the fiber network30may be configured to limit expansion of the balloon20in a single direction, e.g., along a longitudinal axis of the fibers32when the balloon20is expanded and the fibers32are subjected to tensile load, as can be seen inFIGS. 1A and 1B.

Optionally, the fiber network30may include multiple sets of fibers (not shown) that limit expansion of the balloon20in multiple directions, e.g., as illustrated inFIGS. 3A-3C.

As shown inFIG. 3A, if there is only one layer and all the fibers32aof that layer run in the same direction (e.g., along an x-axis), expansion is most limited in the direction of the fibers (along the x-axis). If, as shown inFIG. 3B, the fibers32a,32b,32cwithin a particular layer run in multiple directions (e.g., along the x-axis, y-axis, or both axes), expansion is limited in all directions lying within the plane of that layer. Further, as shown inFIG. 3C, a multiple-layer fiber network may impose stricter limitations on the shape and dimensions of the expanded balloon within a plane parallel to the layers (along the x-axis and y-axis) than in the direction perpendicular to the layers (along the z-axis). The in-plane expansion of a layered multi-direction (x-axis, y-axis, and z-axis) fiber network depends largely on the elasticity of the fibers, whereas z-axis expansion depends on the elasticity, stiffness and inter-connection distance.

The membrane30may be formed from substantially elastic or other impermeable material depending on whether the balloon20is intended to be compliant or semi-compliant, and/or depending on the intended shape and pressure requirements. The overall shape of the balloon20may be configured based on the corresponding shape of a body structure being compressed and/or otherwise engaged by the balloon20. For example, the balloon20may be configured to provide a compression surface26bin the expanded configuration similar to a body structure to be compressed during a medical procedure.

Returning toFIGS. 2A-2D, a rectangular balloon20is shown that includes a membrane22that includes a layer of adhesive on the inner surface24, and a rectangular mass of fibers32providing the fiber network30. In addition, the balloon20includes an inflation port40communicating with the interior space28to direct the balloon20between the compressed configuration shown inFIGS. 2C and 2Dand the expanded configuration shown inFIGS. 2A and 2B, thereby providing the compression surface26b. Upon inflation, the internal pressure is distributed evenly through the compression surface, despite the irregularity of the body structure being compressed.

The balloon20may be collapsed to the compressed configuration through the combined effects of compression and suction. For example, a source of vacuum, e.g., a syringe, suction line, and the like (not shown), may be coupled to the inflation port40(e.g., via the side port52ashown inFIG. 1) and fluid aspirated from the interior space28, thereby causing the membrane22to collapse inwardly and compress or collapse the fibers32of the fiber network30. For example, if the fibers32are substantially inelastic yet flexible, the fibers32may simply relax when tension is removed as the membrane22is drawn inwardly or if a multiple dimensional network is provided, the fibers may compress inwardly, similar to a sponge compressing.

Conversely, when the balloon20is to be expanded, a source of inflation media, e.g., the same syringe, a fluid line, and the like (not shown), may be coupled to the inflation port40and fluid may be delivered into the interior space28to expand the membrane22. When the membrane22expands sufficiently, the fibers32may be subjected to tensile forces, e.g., thereby preventing further expansion of the membrane22if the fibers are substantially inelastic.

To make the balloon20, the fibers32of the fiber network may be bonded or otherwise attached to the inner surface24of the membrane22. In one embodiment, a layer of adhesive (not shown) may be applied to the inner surface24and ends of the fibers32may be attached to the inner surface24such that the fibers32extend across the interior space28in a desired manner. For example, opposites ends of the fibers32may be attached to different locations of the inner surface24, e.g., generally opposite one another or otherwise to orient the fibers along a desired axis.

Alternatively, the fibers32may be bonded or otherwise coupled together to provide a mass of fibers that are then inserted into the interior space28of the membrane20and bonded collectively to the inner surface24. In a further alternative, the fibers32may be attached together within a porous material, e.g., a fabric and the like (not shown), to create an encased fiber network30, with the porous material providing an outer surface for the fiber network30that may be attached to the inner surface24of the membrane20.

In a further alternative, the interior space28of the balloon20may be substantially filled with a sponge or other similar filler material having a predetermined relaxed shape corresponding to the desired outer dimension of the balloon20, yet resiliently compressible inwardly similar to the fiber network described herein. For example, the filler material may be formed from substantially inelastic material that prevents expansion beyond the relaxed shape, yet allows the filler material to be compressed inwardly. In this alternative, an outer surface of the filler material may be attached to the inner surface of the membrane22to prevent separation of the membrane from the filler material. Thus, expansion of the membrane22may be limited by the predetermined relaxed shape of the filler material.

The resulting balloon20may be attached to a catheter or other tubular member, such as the catheter8shown inFIG. 1, to allow introduction into a patient's body. For example, the balloon20may be attached to the distal end14of the tubular member10, e.g., such that the distal end14of the catheter8terminates on one end of the balloon20, e.g., providing the inflation port40shown inFIGS. 2A-2D.

Alternatively, the distal end14of the tubular member10may extend through the balloon20, e.g., as shown inFIG. 1. For example, the membrane22may include proximal and distal ends that are attached to the catheter distal end14such that the ends are spaced apart from one another. In this alternative, the fiber network30may be located within the interior space28of the membrane22surrounding the catheter distal end14. Optionally, the fibers of the fiber network30may be coupled to the wall of the catheter distal end14in addition to the inner surface24of the membrane22.

In another alternative, the distal end14of the tubular member10may be coupled to the proximal end of the membrane22and a separate tip member (not shown) may be coupled to and extend from the distal end of the membrane22.

To make the balloon20, one or more sections of membrane material may be formed to define one or more sidewalls of the membrane22, e.g., by molding as a single piece, forming multiple sheets and then attaching them together, e.g., by bonding with adhesive, sonic welding, fusing, and the like. The fiber network30may be placed within the interior28of the membrane22after forming one or more of the sidewalls, e.g., by omitting one of the end walls and otherwise forming the rest of the membrane22to allow access to the interior space28. A layer of adhesive may be applied to one or more interior surfaces of the membrane22, e.g., opposite sidewalls, and the fiber network30may be positioned within the interior space28such that ends of the fibers32become bonded to the interior surfaces via the adhesive. In one embodiment, individual fibers32may be positioned and bonded to the interior surfaces. In another embodiment, multiple fibers32may be assembled together, e.g., as shown inFIGS. 3A-3C, and inserted together into the interior space28such that the ends are bonded to the desired interior surfaces. Any remaining sidewalls may then be attached to form the complete membrane22. In an alternative embodiment, the fiber network30may be positioned within the interior space28when the membrane20is initially formed, e.g., by placing the fiber network30within a mold into which membrane material is delivered to form the membrane22directly around the fiber network30. In another alternative, after forming the membrane20, the interior space28may be accessed through an opening in one of the sidewalls, e.g., a neck or other opening used to connect the membrane20to the distal end14of the tubular member10.

During use, the balloon20may be introduced into a patient's body in the compressed configuration and positioned at a desired location, e.g., aligning one or more sidewalls of the balloon20with a correspondingly shaped body structure. For example, the distal end14may be introduced into a body lumen or cavity, e.g., via an access sheath, guidewire, or other instrument (not shown) previously positioned from an access site into the treatment location. If desired, the distal end14may be rotated and/or otherwise manipulated to orient the sidewalls(s) of the balloon20towards a body structure at the treatment location. Optionally, the distal14and/or balloon20may include one or more markers, e.g., radiopaque markers and the like (not shown), to aid in manipulation of the balloon20using external imaging, such as fluoroscopy.

Once properly positioned, the balloon20may be expanded to the expanded configuration, e.g., to press the sidewall(s) of the balloon20against the body structure. In exemplary embodiments, the balloon20may be used to apply pressure to the body structure, e.g., with the irregularly shaped sidewall(s) applying a substantively uniform pressure to the similarly shaped surface of the body structure. In addition, the balloon20may enhance apposition or contact with the body structure to provide additional treatments, e.g., deliver one or more drugs or agents from the sidewall(s) to the body structure, deliver energy via the balloon20, and the like. For example, the balloon20may carry one or more treatment elements, e.g., coatings, porous members, electrodes, delivery devices, and the like (not shown) that may be used to provide additional treatment.

Providing the internal support structure30within a compliant balloon20may limit shape and/or size shape of the balloon20in the expanded configuration, allowing the balloon20to be inflated to relatively high pressures compared to conventional compliant balloons. Without the internal support, high-pressure inflation of a compliant balloon may cause it to expand uncontrollably wherever the body lumen is widest or weakest and/or can risk rupture of the balloon.

Turning toFIGS. 4 and 5, in another application, the balloons and/or catheters herein may be used to support a tubular graft or stent.FIG. 4shows an exemplary embodiment of an internally supported balloon120, which may be constructed similar to any of the embodiments herein, expanded within a tubular prosthesis110, which may be a stent, stent-graft, or other tubular device configured for implantation within a body lumen.

Several current devices employ inflatable rings or spirals to provide structural support and enhance sealing, e.g., as demonstrated by the balloon150shown inFIG. 5including one or more rings160. Like all balloons, each ring160has a circular cross-sectional profile with a depth (outer wall to inner wall) that matches its length (parallel to the long-axis of the prosthesis). To minimize luminal impingement, the ring160has to be relatively narrow.

In contrast, as shown inFIG. 4, the presence of a fiber support structure130within the interior of the balloon120allows the otherwise circular cross-sectional profile to become rectangular. The resulting supporting annular body may then become longer than it is deep, which maximizes the length of the contact zone while minimizing luminal impingement. Thus, the overall length and thickness of the balloon120may be set as desired using the internal supporting structure, e.g., to correspond to the prosthesis110being supported.