AU1639900A - Medical appliance for the treatment of a portion of the body vessel by ionizing radiation - Google Patents

Description

m S&F Ref: 301389D2

AUSTRALIA

PATENTS ACT 1990 COMPLETE SPECIFICATION FOR A STANDARD PATENT

ORIGINAL

r r r Name and Address of Applicant: Actual Inventor(s): Address for Service: Invention Title: Schneider (Europe) GmbH Ackerstrasse 6 CH-8180 Bulach Switzerland Vitali Veri and Youri Popowski Spruson Ferguson St Martins Tower 31 Market Street Sydney NSW 2000 Medical Appliance for the Treatment of a Portion of the Body Vessel by Ionizing Radiation The following statement is a full description of this invention, including the best method of performing it known to me/us:- 5845c Medical appliance for the treatment of a portion of body vessel by ionizing radiation This invention relates to a medical appliance for the treatment of a portion of body vessel by ionizing radiation, comprising a catheter, an inflatable elongated balloon distally surrounding the catheter, and lumen means longitudinally extending through the catheter for positioning a radioactive radiation emitter within the balloon.

US Patent N* 5,213,561 describes a device for preventing restenosis after angioplasty comprising, among various embodiments, a catheter having a o1 balloon at its distal end and a center core or tube in which a conventional •guidewire is receivable. Particles or crystals of radioactive material are Sembedded in or mounted on the tube inside the balloon and a retractable shielding sleeve is slidable along the tube to cover the radioactive source, blocking exposure to radiation until it is shifted away. Such a structure is said to is allow radiation of a vascular structure immediately following completion of angioplasty, without separately inserting a radiation source.

Standard dilatation balloons are not well suited to transport and to take up radioactive radiating sources because the center core or guidewire lumen tends to warp on the stretch inside the balloon, thereby forming an undulated line. The radioactive radiation source, however, has to be centered as exactly as possible inside the vessel in order to avoid the vessel wall being burned.

The document DE-9102312.2 describes balloon catheters for performing angioplasty procedures followed by radioactive irradiation to prevent restenosis.

In a first embodiment, there is provided a catheter closed at its distal end and bearing a dilatation balloon which can be inflated by a fluid medium supplied via a lumen extending longitudinally of the catheter; a radioactive seed affixed to the end of a guidewire may be inserted into the catheter lumen to be brought into the site of angioplasty while the balloon is inflated; according to a variant, the lumen of the catheter may be separated in two parallel channels by a longitudinally extending intermediate wall, one of the channels being for insertion of the fluid for inflating the balloon and the other for insertion of a guidewire having the radioactive seed affixed at its end. In a second embodiment, the catheter comprises an additional channel centered in the catheter lumen by means of two longitudinally extending intermediate walls; the catheter lumen is thus divided into three channels, of which the central channel is for insertion of a radioactive pin affixed at the end of a guidewire and the lateral channels for balloon inflation and for supplying drugs into the blood vessel, respectively. In a third embodiment, the catheter bears two balloons at a distance from one another and which can be inflated separately; the catheter also comprises a central channel centered in the catheter lumen by means of four longitudinally extending walls defining four channels surrounding the central channel; two of the surrounding channels are respectively opening into 2o the balloons for inflation thereof, and the two other surrounding channels are respectively opening between the two balloons to allow injection of drugs in the vessel area comprised between the two balloons; the document indicates that a radioactive seed affixed to the distal end of a guidewire may be placed in the lowest of the surrounding channels; the document also indicates that the radioactive source may be placed in the central channel, further outlining that, as with the second embodiment, the radioactive source may even be driven out of the catheter to directly irradiate the vessel. Apart from the fact that this document does not consider any particular centering of the radioactive source in the body vessel, its various configurations do not allow such a centering.

In the first embodiment of this document DE-9102312.2 no measures are described which would ensure circumferentially uniform radiation impact on the vessel wall and the radial position of the irradiation source is merely determined by gravity, whereby warping of the catheter lumen upon inflation of the balloon will add to the unevenness of radiation distribution in the vessel. In the second embodiment, any warping upon inflation of the balloon will be fully uncontrollable because of the different reactions of the main channel, additional 1o channel and longitudinal walls of the catheter to the stresses resulting from the o stretch inside the balloon; this of course makes it impossible to know where and how the radioactive radiation will be distributed in the vessel. In the third embodiment, the situation shows the same drawbacks as for the second embodiment, with some more uncertainty resulting from the additionnal channels.

The document DE-3620123-A1 discloses an apparatus for measuring and :irradiating body cavities which permits the placing and positioning of a light oconductor at the center of a cavity in order to achieve homogeneous lighting thereof via a dispersing agent. To this effect, a light conductor is located in a 20 tubular catheter surrounded by two optically transparent centering flexible balloons at a distance from each other and which are inflated by a dispersing agent in order to have them rest against the wall of the body cavity. The portion of the catheter which is located between the balloons is stiffer than the rest of the catheter to avoid modification of the distance between the two balloons, for instance due to curving of the catheter. The system is said to be usable for a blood vessel, and the two balloons are occlusion balloons. Occlusion balloons have to be resilient to safely fulfill their task in a vessel of unknown exact shape and size. Because of this resiliency, occlusion balloons can not be used simultaneously as dilation balloons. Resilient balloons would overstretch the vessel wall when used with the higher pressures that are required for a successful angioplasty. Of course the doctor has control over the inflation pressure with resilient balloons same as with dilation balloons, but this is not sufficient for safe angioplasty. With a resilient balloon the doctor has no control over the inflated diameter or over the shape to which the balloon is inflated. Of course, with this apparatus the source could be centered if the balloons are close together, but the additional weldings of two balloons close together make the catheter more complicated and expensive. Furthermore, the added weldings reduce the flexibility of the catheter which is necessary to manoeuvre it through tortuous vessels and to use it in tortuous vessels.

The purpose of this invention is to improve the conditions of radioactive radiation treatment of the body vessels by proposing a medical appliance with an inflatable balloon for a vessel wall radiation which is uniform around the vessel, an i appliance that is highly versatile, simple to manufacture and easy to use.

~In a broad form the present invention provides a balloon catheter for treatment of a portion of a blood vessel by ionizing radiation, comprising: a catheter shaft having a lumen sized to receive an ionizing radiation emitter; and a balloon disposed about a distal portion of the shaft, the balloon having at least 20 three sets of contact points, when viewed in longitudinal cross-section, such that the catheter is substantially centered in the blood vessel, despite curvature thereof.

in another broad form the present invention provides a system for treatmcint of a portion of a blood vessel by ionizing radiation, comprising: an ionizing radiation emitter; and a balloon catheter, the balloon catheter comprising a shaft having a lumen sized to receive the ionizing radiation emitter and a balloon disposed about a distal portion of the shaft, the balloon having at least three lobes such that the catheter is substantially centered in the blood vessel, despite curvature thereof.

In that way, the catheter allows use of the technology known under the trade mark MONORAIL and the waist centers the lumen containing the radioactive radiation emitter inside the body vessel at least at the location thereof and substantially eliminates any undulated shape which may be taken by the catheter or lumen containing the radioactive radiation emitter. The stretch occurring upon inflation of the balloon therefore does not affect the positioning.

II:\DAY LI13\1 ibLL]091 14.doc:TCW of the radioactive radiation emitter within the body vessel. And the appliance may retain a good flexibility allowing its manoeuvre and use in tortuous and/or narrow vessels. A two lumen catheter construction is thus achieved which will be easily centred within the balloon by the waist.

s Specifically, it becomes possible to improve dosage control of the radioactive radiation with regard to the distance between radioactive source and vessel wall, whereby overdosage because of too narrow distance and underdosage because of too wide distance to the vessel wall is avoided, and the impact of radiation on the vessel wall is essentially uniform.

0 10 The waist may be created by belt means which may be regularly or irregularly S• spaced from one another over the length of the balloon in order to match any structural configuration and warping tendency of the catheter and balloon assembly.

For inexpensive fitting of existing balloon catheters, the belt means may be made of surgical thread, possibly surgical thread tied with a knot.

To modulate the centering of the catheter within the balloon, the belt means may be made of moulded rings, the length and thickness of which will be chosen as a function of the strength needed to counteract the warping tendency of the catheter.

For safety purposes, the lumen means may be closed distally.

These and other objects will become readily apparent from the following detailed description with reference to the accompanying drawing which show diagrammatically and by way of example one embodiment of the invention.

Figures 1 is a longitudinal cut of the said embodiment.

s In the embodiment shown only the portions of the medical appliance which have to be located at the site of treatment have been depicted, the other portions of the embodiment being devised as currently practised in the art. The portion of the body vessel where treatment occurs has not been shown.

The described materials are specifically directed to percutaneous transluminal 1o angioplasty. This is however not limitative and the invention is also applicable to materials directed to the treatment of other body vessels.

The embodiment of Figure 1 is a balloon catheter which makes use of the MONORAIL (trade mark) catheter technology. This balloon catheter comprises a catheter tube 31 distally surrounded by an elongated balloon 32 affixed to the catheter tube. Within the catheter tube 31 is a longitudinal lumen 33 preferably distally closed at a location 40 substantially corresponding to the distal end of balloon 32, which lumen 33 is for allowing passage of a guiding wire 36 provided with a distal radioactive radiation emitter 35, in this example in the form of a coiled filament, the travel of which is limited for safety purposes by the closed distal end 40 of lumen 33. The catheter also comprises a lumen 34 for supplying inflation fluid to the balloon 32. The catheter 31 further comprises a guidewire lumen 41 with an entry 42 and exit 43 distal of the balloon 32 for accomodating a guidewire 44 in the MONORAIL (trade mark) configuration.

A waist is created by two belt means 37 which are formed of moulded rings regularly spaced from one another over the length of the balloon 32 and which are mounted on the balloon and adhesively secured thereto for essentially centering the catheter 31 within the balloon 32. Belt means 37 squeeze the balloon 32 to nearly the diameter of the catheter 31 and thereby leave a small passage 38 for the inflation fluid ejected by lumen 34. Belt means 37 divide the balloon 32 into similar sections 39 and they assure a close center fit of catheter 31 within the balloon 32, at least at the respective locations of the lace. This structure substantially eliminates the effects of catheter warping upon inflation of o the balloon and therefore the lumen 33 and radioactive radiation emitter 35 in sliding fit therein will be essentially centered in the body vessel, at least at the locations of lace.

Variants may be envisaged.

For instance, the belt means may be made of surgical thread; they may be 1s made possibly of surgical thread tied with a knot.

0 The belt means may also be made of moulded rings of different length and/or thickness.

The belt means may be irregularly spaced from one another over the length of the balloon. Within this frame, it is possible to have a repartition of belt means providing a central section of the balloon which is longer than a proximal and a distal section thereof.

It is possible to have more than two belt means to constitute the waist in case of long balloon configurations as well as it is possible to have only one belt means forming a waist in case of relatively short balloon configurations.

The belt means may be simply squeezing the balloon, without being affixed thereto. They may also be affixed to the balloon by welding.

And of course, the radioactive radiation emitter may be of any shape, configuration or material, other than the coil or filament described.

Claims (17)

1. A balloon catheter for treatment of a portion of a blood vessel by ionizing radiation, comprising: a catheter shaft having a lumen sized to receive an ionizing radiation emitter; and a balloon disposed about a distal portion of the shaft, the balloon having at least three sets of contact points, when viewed in longitudinal cross-section, such that the catheter is substantially centered in the blood vessel, despite curvature thereof.

2. A balloon catheter as in claim 1, wherein the sets of contact points are defined by balloon lobes.

3. A balloon catheter as in claim 2, wherein the balloon comprises a single balloon.

4. A balloon catheter as in claim 2, wherein the lobes are defined by waists on either side thereof.

5. A balloon catheter as in claim 4, wherein the waists are regularly spaced 15 from one another along the length of the balloon.

6. A balloon catheter as in claim 5, wherein the waists are defined by belts.

7. A balloon catheter as in claim 2, wherein the shaft includes an inflation lumen for inflating and deflating the balloon.

8. A balloon catheter as in claim 7, wherein the shaft includes a guidewire 20 lumen sized to receive a guidewire.

9. A balloon catheter as in claim 8, wherein the guidewire lumen extends through the balloon.

10. A balloon catheter as in claim 8, wherein the guidewire lumen has a proximal opening disposed distal of a proximal end of the shaft.

11. A balloon catheter as in claim 8, wherein the guidewire lumen has a proximal opening disposed distal of the balloon.

12. A balloon catheter as in claim 2. wherein the radiation emitter lumen has a closed distal end.

13. A balloon catheter as in claim 2, wherein the radiation emitter lumen has an open distal end.

14. A balloon catheter as in claim 13, wherein the open distal end of the radiation emitter lumen has a reduced diameter.

A system for treatment of a portion of a blood vessel by ionizing radiation, comprising: an ionizing radiation emitter; and I :\)AY1.l 1\ibLO190 14.doc:'IlCW see.. 0 .00. 0 00 0000 .000 a balloon catheter, the balloon catheter comprising a shaft having a lumen sized to receive the ionizing radiation emitter and a balloon disposed about a distal portion of the shaft, the balloon having at least three lobes such that the catheter is substantially centered in the blood vessel, despite curvature thereof.

16. A system as in claim 15, wherein the ionizing radiation emitter comprises an elongate filament.

17. A balloon catheter for treatment of a portion of a blood vessel by ionizing radiation, said balloon catheter being substantially as hereinbefore described with reference to the accompanying drawing. o Dated 10 February, 2000 Schneider (Europe) GmbH Patent Attorneys for the Applicant/Nominated Person SPRUSON FERGUSON Il:\DAYLIB\liibLL09114.doc:TCW I