# Patent

## Title
Balloon catheter and method for manufacturing it

## Abstract

A balloon catheter includes a catheter tube and an inflatable balloon. The ends of the balloon are attached to the catheter tube. The outside surface of the balloon in an uninflated state is provided with a relief structure which in an inflated state of the balloon is substantially disappeared. A method for producing such a relief structure is by winding a wire helically around the outer surface of the balloon.

## Background
This application is a continuation of U.S. Pat. No. 8,388,641, filed Dec. 27, 2010, which is a continuation of U.S. Pat. No. 8,083,761, filed May 7, 2002, the full disclosures of which are incorporated herein by reference.


TECHNICAL FIELD
The present invention relates to a balloon catheter comprising a catheter tube and an inflatable balloon which at its ends is attached to the catheter tube. The invention further relates to a method of manufacturing a balloon catheter.
BACKGROUND INFORMATION
Balloon catheters of this type are generally known and are used for dilating vessels and lumina. In order to pass the balloon catheter easily and safely through the vessels and lumina and to position it at the required place for dilatation, it is important that the balloon catheter has a small profile and is sufficiently flexible.
The object of the invention is therefore to provide an improved balloon catheter.
BRIEF SUMMARY OF THE INVENTION
The balloon catheter according to the invention is characterized in that the outside surface of the balloon in an uninflated state is provided with a relief structure which in an inflated state of the balloon is substantially disappeared.
Tests have shown that with a relief structure on the outside surface of the balloon, a catheter is obtained that is more flexible than a standard balloon catheter. The balloon catheter according to the invention can therefore be passed more easily and more safely through vessels and lumina to the point of dilatation. Because of its flexibility, the catheter will be able to adapt better to a bend in a vessel or a lumen, thus reducing the risk of damage to the vessel or lumen.
The required relief structure may have different embodiments, but preferably comprises at least one groove that extends at least transversely in the longitudinal direction of the balloon in order to give the catheter the required flexibility in a direction transverse to the longitudinal direction thereof.
The groove preferably extends at a predetermined angle with respect to the longitudinal direction of the balloon. According to a preferred embodiment the groove extends helically from one end to the other end of the balloon, over the outside surface thereof.
According to another embodiment, the relief structure comprises two or more grooves that extend helically from one end to the other end of the balloon, crossing each other. Tests have shown that with such a relief structure a very flexible balloon catheter is obtained which also has a relatively small profile.
The invention also relates to a method for producing a balloon catheter comprising attaching the ends of an inflatable balloon to a catheter tube, whereby according to the invention the outside surface of the balloon is provided with a relief structure.
According to an embodiment of the invention, the relief structure is produced on the application of heat in order to deform the elastic material of the balloon.
The relief structure is also preferably produced on the surface of the balloon by applying a high pressure to the inside of the balloon.
According to a very inexpensive method, the relief structure is produced on the surface of the balloon by winding a wire around the balloon in the form of a helix.
According to another simple method, the relief structure is produced on the surface of the balloon by taking up the balloon in a counter-pressure body that has the relief structure.



BRIEF DESCRIPTION OF THE DRAWINGS
The invention is explained in more detail on the basis of the drawings attached. The drawings show:
FIG. 1A is a side view of a first embodiment of a balloon catheter in an uninflated state,
FIG. 1B is a side view of the catheter in FIG. 1A in an inflated state,
FIG. 2A is a side view of a second embodiment of a balloon catheter in an uninflated state, and
FIG. 2B is a side view of the catheter of FIG. 2A in an inflated state.



DETAILED DESCRIPTION OF THE INVENTION
A balloon catheter according to the invention comprises a catheter tube 1 and an inflatable balloon 2, which at its ends is attached to the catheter tube 1. In an uninflated state (FIGS. 1A and 2A), the outside surface of balloon 2 has a relief structure 4 that in the inflated state has virtually or completely disappeared (FIGS. 1B and 2B). The relief structure gives the catheter its required flexibility.
In the first embodiment according to FIGS. 1A and 1B, the relief structure 4 consists of one groove 5, which extends helically from one end 3 to the other end 3 of the balloon 2, over the outside surface thereof. The uninflated balloon 2 has thereby obtained a helical relief surface. In the second embodiment according to FIGS. 2A and 2B, the relief structure 4 consists of two grooves 5, 6, which extend helically from one end 3 to the other end 3 of the balloon 2 and thereby cross each other. The uninflated balloon 2 has hereby obtained a padded relief surface.
Other relief structures are of course possible, provided that the relief structure on the catheter creates the necessary flexibility in a direction transverse to the longitudinal direction of the balloon.
One way of obtaining the relief structure as shown in the drawings is by winding a wire helically around the balloon 2. If the wire is wound only in the forward direction, the structure according to FIG. 1A is obtained, and if the wire is also wound in the return direction, the structure in FIG. 2A is obtained. After the wire has been wound around the balloon, a sleeve is pulled over the balloon. Subsequently, with the application of raised pressure to the inside of the balloon, the balloon is heated in such a way that, in an uninflated state, the balloon obtains a relief structure that on dilating of the balloon at the dilatation site in the vessel or lumen will virtually or completely disappear. The sleeve is then removed and the balloon catheter can be inserted into a vessel or a lumen.
Instead of winding a wire, the balloon may be placed in a mould, which is provided with the relief pattern required in order for it to obtain, under raised pressure and temperature, the relief structure required.
Before the balloon is provided with its relief structure, preferably it is folded in the usual way in order to reduce its profile. By applying the relief structure, the profile will be reduced still further as an additional, advantageous effect.
The usual way of folding a balloon mounted on a catheter involves the folding of the uninflated balloon wall so that wall overlaps itself and defines portions of the balloon wall that are within a fold. A folded balloon has exposed portions of the folded balloon that are exposed to an exterior environment of the balloon, and unexposed portions that are not exposed because those portion s are contained within a fold of the folded balloon.
Note that, although it is not shown in the drawings, it is possible to provide the outside surface of the balloon with various helical grooves that cross each other.

## Claims

1. A balloon catheter comprising:
a catheter shaft disposed on a longitudinal axis;
and
a balloon including opposite ends attached to the catheter shaft, and further including an outside surface that, when the balloon is in an uninflated and folded state, comprises a plurality of helical grooves intersecting one another that substantially disappears when the balloon is in an inflated state at an intended operating pressure during use,
wherein the helical grooves remain unoccupied and
wherein the balloon in the folded state includes a plurality of circumferential folds, such that at least one first portion of the outside surface is not exposed to the exterior environment and one second portion of the outside surface is exposed to the exterior environment, and wherein at least one groove is present on the second portion of the outside surface, but not present on the first portion of the outside surface.

2. The catheter of claim 1, wherein the balloon includes a frustoconically shaped section on each of the opposite ends and a barrel shaped section between said frustoconically shaped sections.

3. The catheter of claim 2, wherein at least one groove extends at least partially along the barrel shaped section.

4. The catheter of claim 2, wherein at least one groove extends at least partially along one of the frustoconically shaped sections.

5. The balloon catheter of claim 1, wherein the helical grooves are independent of the plurality of folds.

6. A balloon for use with a catheter shaft, said balloon comprising:
a balloon wall having an uninflated configuration and an inflated configuration;
wherein in the uninflated configuration, the balloon wall overlaps itself to form a plurality of folds, and an outer surface of the balloon wall further includes at least one relief structure comprising a helical groove extending circumferentially around the balloon and along a longitudinal axis of the balloon;
wherein in the inflated configuration, the plurality of folds and the at least one helical groove is substantially disappeared;
wherein the helical groove remains unoccupied; and
wherein the outer surface of the balloon wall within the fold does not include the helical groove and the outer surface of the balloon wall external to the fold does include the helical groove.

7. The balloon of claim 6, wherein the balloon wall includes a proximal end and a distal end, and wherein the proximal end and the distal end are adapted to attach to the catheter shaft.

8. The balloon of claim 6, wherein at least one helical groove is independent of the plurality of folds.