AU7182798A

AU7182798A - Prepared catheter

Info

Publication number: AU7182798A
Application number: AU71827/98A
Authority: AU
Inventors: Cirillo Ghielmetti; Michael Schwager
Original assignee: Schneider Europe GmbH
Current assignee: Schneider Europe GmbH
Priority date: 1997-09-26
Filing date: 1998-06-12
Publication date: 1999-04-15
Also published as: CA2244038A1; EP0904799A1; JPH11114067A

Description

S F Ref: 422129

.AUSTRALIA

PATENTS ACT 1990 COMPLETE

SPECIFICATION

FOR A STANDARD

PATENT

ORIGINAL

:3 Name and Address of Applicant: Actual Inventor(s): Address for Service: Invention Title: Schneider (Europe) GmnbH Ackerstrasse 6 cH-8180 Bulach

SWITZERLAND

Michael Schwager and Cirillo Ghlelmetti Spruson Ferguson, Patent Attorneys Level 33 St Martins Tower, 31 Market Street Sydney, New South Hales, 2000, Australia Prepared Catheter The following statement is a full description of this invention, including the best method of performing it known to me/us:-

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a P"r~ Description The invention relates to a prepared catheter for intraluminal treatment of a vessel section, which c 2 theter has an elongate shaft with a proximal end and a distal end, a balloonh', hich is arranged at the distal end of the shaft and can be inflated to a maximum use volume, and:.n inflation lumen which r ns through the shaft and opens into .the billoon, and which catheter is filled an inflation medium for applying pressure to the ballooni Balloon catheters are used, for example, for axial sealing or radial expansion of vessels of the body. A common and typical intervention using a balloon catheter is percutaneous transluminal angioplasty inthe peripheral or coronary blood vessel 1 system. In these vessels, stenosed areas formed by deposits are widened by inflating a dilation balloon in order to restore an adequate cross-section of flow to the blood. In addition, balloon catheters are also used as transport and expansion i eans for balloon-expandable stents. These involve a small support tube which is for the most part made of metal and which, during or after balloon dilation, is 20. plastically deformed by the expanding balloon. With the aid of the plastic S deformation, it is implanted in the widened vessel section and is intended to prevent S restenosis of this vessel section. It is also known to seal off a section of a blood vessel.by means of two occlusion balloons which are arranged one behind the other on a balloon catheter and to infuse into the interspace a medicinal product for 25 treating the vessel, and to suction off possible reaction products from the interspace.

Balloon catheters generally have a lumen running along their entire length, or along only a distal section, and receiving a guide wire which has been positioned 30 beforehand in the vessel and along which the balloon catheter is advanced until it reaches the vessel section that is to be treated. In so doing, the balloon catheter passes through a guide catheter which has similarly been put into position beforehand and which bridges the puncture site and the large-lumen portion of the vessel. During treatment, contrast medium for fluoroscopic visualization of the catheter positions, and of the success of the treatment, is injected through the i 1r~ io ~cpj $i s ;i- 7.r- ;r,

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2 annular lumen between balloon catheter and guide catheter. Once the balloon catheter has been brought into position, the balloon is filled with physiological saline solution or contrast medium via an inflation lumen and is pressurized, as a result of which the balloon expands.

The increasing importance of minimally invasive surgery and the treatment of ever narrower blood vessels demand guide catheters, and consequently balloon catheters, of ever smaller profile. Flexibility as well as thrust and torsion transmission of guide wire, balloon catheter and guide catheter must be guaranteed, as well as low friction between guide wire and balloon catheter. An adequately short deflation time for the balloon and a sufficiently large annular lumen *i for the flow of contrast medium are also necessary.

If the inflation lumen is too narrow, the inflation medium can no longer flow quickly enough out of the balloon. A catheter with slow emptying of the balloon blocks the

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bloodstream for longer and thus, for example, also precludes the possibility of responding quickly to an ischaemic reaction on the part of the patient during treatment.

S. 20 The invention is therefore based on the object of providing a balloon catheter of the type mentioned in the introduction, which balloon catheter has short deflation times and has a small overall profile.

According to the invention, the object is achieved by means of a catheter of the type mentioned in the introduction and having the features of the characterizing clause of one of Patent Claims 1 and 3. When the inflation medium used is a medium with a lower viscosity than the water-based inflation media, it is possible, while having essentially the same deflation time, for the inflation lumen to be made smaller in cross-section along the greater part of its length running within the patient during treatment, with great advantages for all other properties of the catheter. For example, as a result of the smaller overall profile, the flow of contrast medium is.

improved, while at the same time, however, the flexibility and the kink resistance are also improved, since with smaller shaft diameters the wall thickness can be 4" 1 reduced. The reduction in cross-section which can be achieved by means of the invention can either be specified in absolute values, as specified in the claims, or, 3 as specified in other claims, as a function of the maximum use volume of the balloon which has to be deflated.

If a gas is used as inflation medium, the advantages of the invention become especially evident. Gas-filled balloons have up to about three times shorter deflation times compared to balloons which have been inflated with liquid. Accordingly, the cross-sectional area of the inflation lumen can be reduced in this case.

In a preferred embodiment of the invention, the inflation medium is carbon dioxide.

0 In the treatment of blood vessels, it is possible, in the event of a leaking or defective balloon, for the blood to absorb a certain amount of carbon dioxide without harming the patient. Since carbon dioxide is transported anyway in the blood, its biological /tolerability in humans is not in question.

Further properties of a catheter according to the invention will become apparent i from an illustrative embodiment which is described in detail hereinbelow with reference to the drawing. This example involves a catheter for intraluminal treatment of a vessel section with ionizing radiation. Controlled deflation times, with a small shaft cross-section, are of particular interest here. In the case of protracted irradiation times, as can result from the abating energy of the emitter, the burden on 1 the patient is minimized by interrupting the flow of blood. The advantages of the invention are seen not only in this application, however, but in all balloon catheters whose deflation time and whose overall profile are of interest, such as in the case of the catheters mentioned in the introduction, in the case of dilation catheters or 25 occlusion catheters for use in coronary or peripheral blood vessels or in neurology, and in the case of other catheters. In the drawing: FIG. 1 shows, in a longitudinal cutaway, the distal section of a catheter according to the invention.

According to FIG. 1, a catheter according to the invention for intraluminal treatment of a vessel section with ionizing radiation has a three-lumen shaft I which has a proximal end (not shown) and a distal end 2, and serves as transluminal access to the vessel section. The shaft 1 is made up of an outer shaft lb and an inner shaft la which runs coaxially inside the latter and projects distally from it. In a tip 3 of the

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4 r *t e es e* i r ^rl h'm ;Ik' inner shaft la there is a short guide-wire lumen 4 for receiving a guide wire (not shown, course indicated by dot-and-dash line onto which the catheter is threaded in order to be advanced through the vessel system. Duringthe insertion of the catheter, a central lumen 6,which is closed distally is used for receiving a stiffening wire (not shown) which transmits axial thrust to the tip 3 as the shaft 1 is being advanced. An annular inflation lumen 7 running between.inner shaft la and outer shaft Ib opens into a-balloon 8 arranged at the distal end 2 of the shaft 1, which balloon 8is filled, via the inflation lumen 7, with an inflation medium 9, for example carbon dioxide, and is thereby inflated. With approximately the same emptying time for the balloon 8, the use of carbon dioxide as inflation medium permits a reduction in the cross-sectional area of the inflation lumen 7, for example to values of less than 0.300 mm 2 although cross-sectional areas of less than 0.200 mm 2 have already been produced. The achievable ratio between the maximum use volume of the balloon and the cross-sectional area of the inflation lumen, with tolerable emptying times, is approximately 1200:1. In order to obtain a thin outer shaft lb, the emptying times evolving from a ratio of 1600:1 have also been accepted in some cases. The inflated balloon 8 is subdivided into a plurality of balloon segments by constrictions which are formed by ring elements 10, as a result of which the central lumen 6 is radially centred even in the event of deformation of 20 the inner shaft la. When the balloon catheter has been positioned, the stiffening wire is removed from the central lumen 6 and replaced by a source wire 11 into which a source 12 of ionizing radiation is incorporated distally. The source 12 is, for example, a filament of The carbon dioxide used as inflation medium is, for example, kept ready in gas bottles at a pressure of 11 bar, for example. The gas pressure can be reduced via a reducing valve, so that an inflation syringe can also be filled with carbon dioxide in the sterile area of a catheter laboratory. Air is removed from the balloon and inflation lumen of the catheter in a customary manner, for instance with a syringe creating a vacuum. The balloon can thereafter be inflated with the carbon dioxide taken up by the inilation syringe.

i List of references :1 Shaft la Inner shaft lb Outer shaft 2 Distal end 3 Tip 4 Guide-wire lumen Guide-wire course 6 Central lumen 7 Inflation lumen 8 Balloon 9 Inflation medium, carbon dioxide S 10 Ring element S. 15 11 Source wire 12 Source 'I Z-

Claims

1. Prepared catheter for intraluminal treatment of a vesel section, which S catheter has an elongate shaft with a proximal end and a distal end, a balloon which is arranged at the distal end of the shaft and can be inflated to a maximum use volume, and an inflation lumen which runs through the shaft and opens into the balloon, and which catheter is filled with an inflation medium for applying pressure to the balloon characterised in that the inflation medium has a viscosity which is lower than that of water, and in that the inflation lumen has, along the greater part of the length lying within water aad 0 n t t S-the patient's body during treatment, a cross-sectional area having a value in not. 1o greater than the maximum use volume of the balloon inamm 3 divided by 1200.-

2. Prepared catheter according to Claim 1, characterised in that the inflation lumen has, along the greater part of the length lying within the patient's body during treatment, a cross-sectional area having a value in mm 2 not greater than the maximum use volume of the balloon in mmn 3 divided by 1600. S 15

3. Prepared catheter according to the preamble of Claim 1, characterised in that the inflation medium has a viscosity which is lower than that of water, and in that the inflation lumen has, along the greater part of the length lying within the patient's body during treatment, a cross-sectional area of at most 0.300 mm 2 S"

4. Prepared catheter according to Claim 3, characterised in that the inflation 2o medium has a viscosity which is lower than that of water, and in that the inflation lumen has, along the greater part of the length lying within the patient's body during treatment a cross-sectional area of at most 0.200 mm 2 Prepared catheter according to one of the preceding claims, characterised in that the inflation medium is a gas.

6. Prepared catheter according to Claim 5, characterised in that the inflation medium is carbon dioxide. mdi. 7. Prepared catheter for intraluminal treatment of a vessel sction, substantially as hereinbefore described with reference to the accompanying drawings. Dated 12 June, 1998 Schneider (Europe) GmbH Patent Attorneys for the Applicant/Nominated Person SPRUSON FERGUSON INALIBC103717:M E