Balloon catheter

The invention relates to a balloon catheter and particularly to a PTCA catheter for dilatation of stenoses in the vascular system.

For the treatment of blood vessels of the vascular system PTCA catheters are used (Percutaneous Transluminal Coronary Angioplasty). This is to balloon catheters, which are pushed over a guide wire through the curvatures of the vascular system to the target site.

The distal tip of a PTCA balloon catheter must have a high compression stability, so that they can narrow stenoses happen. Despite the compression stability, the catheter tip has to be flexible, so that the entire catheter can be introduced into the tortuous vasculature. In conventional PTCA catheters, the distal (patient end) portion of hose, so the tube section beyond the balloon, made of portions of different materials with different mechanical properties. Individual pieces of tubing are successively set and joined by welding. This is associated with high production costs and correspondingly high costs.

A balloon catheter, from which the preamble of claim 1 is described in US 4,960,410 A. In this balloon catheter, the inner tube is provided with a spiral groove that extends from the distal end through the balloon. The spiral-shaped recess serves to increase the flexibility of the inner tube. The region containing the recess is coated with an additional coat to smooth the outer surface of the inner tube. This sheath is covered in the region of the distal end of the inner tube with a cuff which consists of the skin of the balloon.

US 6,165,152 A describes a balloon catheter in which the inner tube is provided in a distal tube portion with cutouts, whereby the flexibility of that tube section is increased. The recesses extend only partially through the tube wall, ie they are not continuous. The recesses produced by a laser beam may consist of a helical line or discrete blind holes. They cause a structuring or roughening of the outer surface of the distal tube portion.

WO 96/09848 discloses a balloon catheter with inner tube and outer tube. The balloon is fixed to the inner tube by heat shrinking. The balloon skin extends beyond the distal end of the inner tube and forms a flexible catheter tip.

The present invention has for its object to provide a balloon catheter, the distal tube portion is processed to achieve a desired flexibility though, but without the smoothness of the surface would be adversely affected.

The balloon catheter according to the invention comprises the features of claim 1. Hereinafter, it is provided that the recesses of continuous or non-continuous discrete holes through the hose wall, and in that the sleeve closely surrounds the entire length provided with recesses of the inner tube. The balloon skin thus extends over the entire structured by subsequent machining surface area of ​​the inner tube into the immediate vicinity of the catheter tip.

Since the recesses consist of discrete holes welded cuff provides better load distribution, whereby local stress peaks are avoided. In addition, the risk of buckling is reduced.

While in the US Patent 6,165,152, the structured region passes through the distal cuff of the balloon and is thereby necessarily covered over part of its length with no particular intention, the balloon skin is inventively used to previously, to cover structured surface and from by removing material induced structural change of the surface to heal. Thus the risk of injury or the detachment of vascular deposits is reduced due to the recesses and in bending of the distal tube portion. The invention is based on the idea that the skin of the balloon has a small thickness and is thus the ideal enclosure for smoothing narrow range over the distal tubular portion of the inner tube.

According to a preferred embodiment of the invention, the distal cuff is welded to the provided with the recesses length. When welding the distal cuff on the weakened by the recesses distal tube portion results in a smooth outer surface, which is advantageous when passing through a stenosis. By welded enveloping layer balloon flexibility of the tubular section is also uniform.

The distal sleeve can consist of a shrink tube. A shrink tubing does by heating back to its original shape. In the present case it shrinks on to the outer surface of the inner tube, wherein additionally a weld joint can be performed.

The preparation of the recesses is preferably carried out with a UV laser or excimer laser or by mechanical means. With laser machining a tapered catheter tip can be formed. Preference is given here a CO₂-Laser. Here, the tube material is not degraded, but fused and moved.

In the following, the invention will be explained in more detail with reference to the drawings of exemplary embodiments.

Show it:<dl id="dl0001"><dt>Fig. 1</dt><dd>is a partial view of the balloon catheter, partially in longitudinal section,</dd><dt>FIG. 2</dt><dd>a side view of the distal tubular section of the inner tube, and</dd><dt>Fig. 3</dt><dd>A second embodiment of a balloon catheter according to the invention.</dd></dl>

The balloon catheter includes an elongated outer tube 10 and an extending in the outer tube inner tube 11th At the distal end of the outer tube 10, a balloon 12 is attached, in which the lumen ends 13 of the outer tube. By injecting a pressurized fluid into the lumen 13 of the balloon 12 is expanded to perform a dilation of a stenosis. The hoses are made of polyamide or of suitable material mixtures.

The inner tube 11 extends through the balloon 12 passes. The distal tube portion 14 terminates in a tapered catheter tip 15 through the lumen 16 of the inner tube 11, a (not shown) guidewire are advanced, which protrudes from the catheter distal tip 15 out.

The balloon 12 is welded with a proximal sleeve 17 to the outer tube 10th At the distal end of the balloon 12 is provided with a distal sleeve 18 that is welded to the inner hose eleventh The cuffs are preferably an integral part of the balloon. They may alternatively be welded or consist of several parts.

The distal tube portion 14 of the inner tube 11 is provided with recesses 20, to increase the flexibility of the hose section. The hose portion 14 is an integral component of the inner tube 11. The recesses 20 are in the present embodiment, holes which are burned by a laser beam and penetrate the catheter wall. Alternatively it is possible to form the recesses as a non-continuous weakening points. The preferred shape of recesses is round. However, the recesses may have any shape, such as elliptical shape with running in the tube longitudinal major axis, or rectangular shape. The preparation of through recesses in the form of holes is simpler and does not lead to unintended leaks, because the entire area of ​​the recesses is covered tightly with the skin 21 of the balloon 12th This means that the cuff 18 extends over the entire length of the recess portion, and all covered recesses. Characterized the outer surface of the distal tube section 14 is smoothed.

Figure 2 shows a side view of the recesses 20 provided with the distal tube section 14 of the inner tube 11, wherein the balloon skin 21 which covers the recesses, shown in phantom. The balloon skin 21 is fully laminated to the hose section 14, in particular by welding. It therefore causes a voltage balancing and bridging the recesses 20th

Figure 3 shows a modified embodiment of the tip portion of the balloon catheter. The area of ​​the inner tube 11, to which the recesses 20 are provided, is covered here with the collar 18 of the balloon 12th On the sleeve 18 a shrink tube sitting 22 extending to the distal end of the inner tube and possibly protrudes above. If the shrink tube 22 is heated, for example, by laser irradiation, the reduction in its diameter. Due to the pressure which the heat-shrinkable tube 22 and exerts by the heat of laser irradiation, the cuff 18 is welded to the inner tube 11 and simultaneously molded. In forming the catheter tip control of the laser process is carried out. The shrink tube 22 remains in this embodiment, after the shrinking process to the catheter.

In a further not illustrated embodiment of the tip portion of the balloon catheter of the shrink hose already described is removed after the shrinking operation of the catheter. The area of ​​the inner tube, on which the recesses are provided, is completely covered in this embodiment of the cuff of the balloon.