WO2005030093A1

WO2005030093A1 - Catheter for implantable medicament carrier

Info

Publication number: WO2005030093A1
Application number: PCT/NL2004/000633
Authority: WO
Inventors: Hendrik Glastra; Petrus Antonius Besselink
Original assignee: Hendrik Glastra; Petrus Antonius Besselink
Priority date: 2003-09-29
Filing date: 2004-09-14
Publication date: 2005-04-07
Also published as: NL1024396C2

Abstract

A catheter assembly for implanting a stent assembly having two expandable supporting rings with a sleeve-like element therebetween, particularly a drug carrier, comprising a guide wire, a catheter body carrying the stent assembly with at the distal end two pairs of abutment elements for the supporting rings and a protective sleeve assembly which surrounds this arrangement, in which the guide wire can be coupled with a first, distal sleeve of the protecting sleeve and this sleeve assembly comprises this first distal sleeve around the distal expandable ring of the stent assembly and a second, adjoining proximal sleeve, movable over the catheter body towards the proximal end thereof.

Description

Catheter for implantable medicament carrier.

The invention relates to a catheter assembly for implanting a stent assembly, having two expandable support rings, which are located at a distance from one another, and a sleeve-like element positioned between them, in a body vessel comprising a guide wire, a tubular catheter body which surrounds the guide wire, bears the stent assembly and bears at the distal end two pairs of stop elements, between each of which one of the two expandable support rings of this stent assembly is enclosed, and with a protective sleeve assembly which surrounds this arrangement.

A catheter assembly of this type is described in PCT application O02/076345.

The technique of locally treating a disorder in a body vessel with the aid of a sleeve-like element which is arranged at a site which is to be treated and forms a medicament carrier is extensively described in the PCT application 091/12779, which was cited in the abovementioned publication. The relevant comments are still valid today.

A stent assembly and its use as described in the first publication cited above, WO02/076345, are based on the insight gained by the inventor that for a disorder which is present in a body vessel, in particular a blood vessel, to be treated as effectively as possible, it is highly expedient when the minimum possible pressure is exerted on the site to be treated by a sleeve-like element which is arranged at the site and is desigή*eeϊ ^■ -in ^"particular as a medicament carrier. This element, i.e. in particular the medicament carrier, should for thispurpose preferably not be dimensionally rigid, but should rather be designed in such a manner that it can bear in a resiliently yielding fashion against the inner wall of the body vessel, being held in place by two support rings which do bear tightly against the body vessel and between which, therefore, the medicament carrier is enclosed. Fig. 10 of the abovementioned publication O02/076345 has already shown a catheter assembly with the aid of which a stent assembly of this type can be positioned in a body vessel. According to this proposal, each support ring of the stent assembly is enclosed between two stop elements which are borne by a catheter body, and the assembly is surrounded by an outermost protective sleeve which can be pulled away in the direction of the proximal end of the catheter body.

An assembly of this type works well if the direction in which the outermost protective sleeve is pulled away coincides with the direction of flow of the body fluid, in particular the blood, in the body vessel (in particular a blood vessel) , so that the flaccid sleeve-like medicament carrier is kept taut by the blood flow. If this is not the case and the direction in which the protective sleeve is pulled out is opposite to the direction of flow of the blood, it is possible for the flaccid medicament carrier to "ride up" under the influence of the blood stream before the support rings have been expanded and fixed, so that it will not bear smoothly against the inner wall of the blood vessel.

It is an object of the invention to overcome this drawback and to create a catheter assembly of the type described in the preamble which overcomes this drawback. According to the invention, this object is achieved by virtue of the fact that the protective sleeve assembly comprises a first, distal enclosing sleeve, which can be coupled to the guide wire and can surround at least the distal expansion ring of the stent assembly, and a second, proximal enclosing sleeve, which adjoins the first enclosing sleeve, can surround the remainder of the stent assembly and interacts with means which can be actuated from outside the body for displacing this second enclosing sleeve toward the proximal end of the catheter assembly.

As will be explained in more detail with reference to the description of the figures, these measures ensure that, depending on the direction of flow of the blood with respect to the proximal end of the catheter body, it is possible to choose between the options of either firstly releasing the proximal expansion ring by retracting the second, proximal enclosing sleeve, which then exposes the sleeve-like element first and then the proximal expansion ring, followed by moving the guide wire forward so that it brings with it the first, distal enclosing sleeve as a result of a pushing force being exerted on it via the guide wire, with the distal enclosing sleeve then releasing the distal expansion ring, or carrying out these operations in the reverse order. In both cases, it is ensured that the medicament carrier bears smoothly against the inner wall of the blood vessel.

Preferably, the means for displacing the second enclosing sleeve towards the proximal end of the catheter assembly are formed by an extended section of this second sleeve itself.

For the first case described above, the first, distal enclosing sleeve can surround only the first distal expansion ring of the stent assembly, in which case the second, proximal enclosing sleeve surrounds both the sleeve-like element and the proximal expansion ring. For the second case, the first, distal enclosing sleeve is longer and surrounds both the distal expansion ring and the sleeve-like element, while the second, proximal enclosing sleeve surrounds only the proximal expansion ring of the stent assembly.

In one advantageous embodiment, the guide wire and the first, distal enclosing sleeve each carry an element of a tension- resistant coupling. In this case, in use the guide wire is introduced into the blood vessel firstly, and then the catheter body is introduced.

In this case, preferably, the first element of the coupling is formed by a thickened portion, provided with a circumferential groove, on the distal end of the guide wire, and the second element of this coupling is formed by the elastically yielding end edge, which tapers toward the centre axis of the first, distal protective sleeve, of this sleeve. The claimed exclusive rights also include a stent assembly to be used in combination with a catheter assembly, in accordance with the invention, which stent assembly comprises two expandable support rings which are located at a distance from another and have an open, diamond-shaped structure, of which those points of the diamond which face one another are connected to one another by tension-resistant threads or wires which are embedded in the surface of a sleeve-like element. This sleevelike element may advantageously perform a therapeutic action and may in particular be a medicament carrier.

It is observed that positioning catheters for stents with a movable protecting sleeve for the stent to be positioned comprising two halves, of which one is movable in the distal direction and the other is movable in the proximal direction are known in the art. WO 95/11055 discloses such a catheter in which the two halves are shifted by increasing the pressure of the medium which is supplied to the inflating balloon. Apart from the fact that such an actuation of the sleeve halves is not very reliable there is no possibility to select the actuation of one halve prior to the actuation of the other halve. Both US 202/0099405 and US 5 201 757 describe embodiments of catheters in which the protecting sleeve is divided into two halves of which the proximal one can be actuated by means of a pulling device and the distal one is coupled to a long auxiliary sleeve, running along the length of the catheter and to be pushed towards the distal end of same to actuate the distal halve of the sleeve. Of course this increases the thickness of the catheter and decreases the pliability thereof. Furthermore in none of these catheters the catheter body is provided with pairs of abutment rings for enclosing the respective two extension rings which support between them the supple stent body which is to be positioned by means of the catheter according to the invention.

The invention is explained with reference to the drawing, in which: Fig. 1 diagrammatically depicts a cross section through a blood vessel having a local disorder and shows the guide wire, which has been introduced as far as this disorder, of this stent assembly according to the invention;

^• 5 Fig. 2 diagrammatically depicts the situation as it should be after a stent assembly with support rings and sleeve-like element, in this case a medicament carrier, has been positioned in this blood vessel;

10 Fig. 3 shows a side view, partially in section, of a stent assembly with medicament carrier which is to be positioned with the aid of the catheter assembly according to the invention;

15 Fig. 4 shows a guide wire of a catheter assembly according to the invention;

Fig. 5 shows a longitudinal section through a complete catheter assembly according to the invention; 20 Figs. 6 to 10 show the various phases of positioning a stent assembly with medicament carrier with the aid of the catheter assembly according to the invention;

25 Fig. 11 shows the stent assembly as it is ultimately obtained and positioned;

Fig. 12 shows a longitudinal section through a variant of the stent assembly shown in Fig. 5.

30 Fig. 1 diagrammatically depicts a longitudinal section through a blood vessel 2 with a local disorder 4, for example a stenosis, of which it is desired to treat it with one or more medicaments, supplied by means of a medicament carrier bearing against the

35 inner wall 2a, all this in the manner described in the publication WO02/076345 cited in the introduction of the specification. Fig. 1 also shows the guide wire 6 of a catheter assembly which is to be described in more detail below and the distal end 6a of which extending as far as beyond the stenosis 4.

Fig. 2 shows the same blood vessel 2, but now with a sleeve-like medicament carrier 8 positioned at the location of the stenosis 4, held in place between two support rings, 10, 12 which are located on either side of the stenosis 4 and are supported against the inner wall 2a of the blood vessel 2.

An example of a stent assembly of this kind which is suitable for positioning in the manner described in the introduction with the aid of the catheter assembly according to the invention is shown in Fig. 3. In this stent assembly, the support ring denoted by reference numeral 10 in Fig. 2 is formed from an expandable ring which is made from a memory metal (nitinol) and has an open structure 14, while the support ring 12 in Fig. 2 is designed in a similar way with an open structure and in Fig. 3 is denoted by reference numeral 16; a number of wires or threads 18, which are embedded in the surface of the weak, sleeve-like medicament carrier 21, are tensioned between the end points of the diamond-shaped mesh openings of these support rings. In the expanded and fitted state, the expanded support rings 14, 16 bear against the inner wall 2a of the blood vessel 2 in the same way as the rings 10 and 12 in this figure, and the medicament carrier 18 bears flexibly against the inner wall of this blood vessel, in the manner shown for the medicament carrier 8 in Fig. 2. The support rings 14, 16 adopt their expanded form after they . have been uncovered.

A catheter assembly for installing the stent assembly described above will be explained with reference to Figs. 4 to 12. It should be noted that in these figures the body vessel into which this catheter assembly is introduced is only indicated in Fig. 11, this for the sake of clarity.

Fig. 4 shows the end of the guide wire 20, of which the distal end 22 bears a thickened portion 24 which is designed with two surfaces 26a, 26b which slope upward from the guide wire 20 and have the groove 28 in between them. A catheter body 30, the distal end of which is designed with a first pair of distal stop rings 32a, 32b and a second pair of proximal stop rings 34a, 34b, has been pushed around the guide wire 20 in the usual way. The compressed first, distal expansion ring 14 is enclosed between the first pair of stop rings 32a, 32b, while the second, proximal expansion ring 16 is enclosed between the second pair of stop rings 34a, 34b. The medicament carrier 21 is located between these rings - cf. Fig. 3.

The distal expandable support ring 14, enclosed between the stop rings 32a and 32b, is surrounded by a first enclosing sleeve 36 with a slightly resilient distal end edge 38 flanged toward its axis, which can latch into the circumferential groove 28 in the thickened portion 24, while the sleeve-like medicament carrier 21, which is still rolled up, the second pair of stop rings 34a, 34b and the second expandable support ring 16 are surrounded by a second enclosing sleeve 38, the distal end 40 of which adjoins the proximal end 42 of the enclosing sleeve 36 and the proximal end 44 of which either continues to outside the body or is provided with a pull element which is extended to outside the body and can therefore be operated from outside the body.

Fig. 6 shows how the inwardly flanged edged 38 latches into the circumferential groove 28 as a result of the catheter body 30 being pushed in the direction indicated by arrow 46, i.e. toward the distal end 22 of the guide wire 20. This causes the first, distal enclosing sleeve 36 to be anchored to the distal end 22 of the guide wire 20. The first, distal enclosing sleeve 36 then always surrounds the first, distal expansion ring 14, and the second, proximal, long enclosing sleeve 38 surrounds the as yet still rolled-up medicament carrier and the second, proximal expansion ring 16.

It is assumed that the blood stream in the blood vessel 2 is flowing from the left to the right in the drawing, i.e. in the direction indicated by the wavy arrow 48, from the distal end of the catheter assembly towards the proximal end thereof. While the guide wire and therefore also the first enclosing sleeve 36 are held in place, the second, proximal enclosing sleeve 38 is then pulled back over the catheter body 30 in the direction indicated by arrow 50 in Fig. 7. As it does so, first of all the weak medicament carrier 21 is exposed, followed by the proximal expansion ring 16 - cf. Figs. 7 and 8. The medicament carrier 21 unfolds but is kept taut by the blood stream running in the direction indicated by arrow 48 - even during the phase of expansion of the proximal expansion ring 16 - and the proximal end 21a of the medicament carrier, fixed to the expansion ring 16, successfully comes to bear against the inner wall of the blood vessel 2.

When the guide wire 20 is then displaced through this catheter body towards the distal end, i.e. in the direction indicated by arrow 46, while the catheter body 30 is held stationary, the situation shown in Figs. 9 and 10 results, i.e. the situation in which first of all the medicament carrier 21 is completely uncovered, and then the first, distal expansion ring 14 is uncovered. This ultimately results in the situation shown in Fig. 10, in which the two expansion rings 14 and 16 are fully expanded and the medicament carrier 21 is held taut between them. Retracting the catheter body 30 together with the guide wire 20 ultimately results in the situation shown in Fig. 11, in which the stent assembly, comprising the support rings 14 and 16 and the medicament carrier 21 located between them is securely anchored in the blood vessel 2, which is illustrated diagrammatically in virtually cylindrical form in this figure for the sake of simplicity.

Fig. 12 shows an embodiment of the catheter assembly in which the first, distal enclosing sleeve 36a is longer and surrounds both the first, distal adjustable support ring 14 and the medicament carrier 21; the second, proximal enclosing sleeve 38a is shorter and surrounds only the proximal, expandable support ring 16. In this case, first of all the longer, distal enclosing sleeve 36a will be moved, so that first of all the distal expandable support ring 14 can expand and only afterward can the proximal expandable supporting ring 16 expand. This embodiment will be used if the direction of flow of the blood is in the direction indicated by arrow 48a, i.e. from the right to the left in Fig. 12. Since it is now the proximal end of the medicament carrier 21 which is released last, the "riding-up effect" will not occur.

It should be noted that, if the shape and configuration of a body vessel allow, the guide wire can be permanently secured to the first enclosing sleeve, so that the entire catheter assembly can be introduced in a single operation.

Furthermore, it should be noted that the invention is not restricted only to the use of a sleeve-like element which is configured specifically as a medicament carrier.

Claims

I -* I / I « «_ 4.U WTT » r w J ^) j CLAIMS

1. A catheter assembly for implanting a stent assembly, having two expandable support rings, which are located at a distance from one another, and a sleeve-like element positioned between them, in a body vessel and comprising a guide wire, a tubular catheter body which surrounds the guide wire, bears the stent assembly and bears at the distal end two pairs of stop elements, between each of which one of the two expandable support rings of this stent assembly is enclosed, and with a protective sleeve assembly which surrounds this arrangement, characterized in that the protective sleeve assembly comprises a first, distal enclosing sleeve, which can be coupled to the guide wire and can surround at least the distal expansion ring of the stent assembly, and a second, proximal enclosing sleeve, which adjoins the first enclosing sleeve, can surround the remainder of the stent assembly and interacts with means which can be actuated from outside the body for displacing this second enclosing sleeve toward the proximal end of the catheter assembly.

2. The catheter assembly as claimed in claim 1, characterized in that the means for displacing the second enclosing sleeve towards the proximal end of the catheter assembly are formed by an extended section of this second sleeve itself.

3. The catheter assembly as claimed in claim 1-2, characterized in that the first, distal enclosing sleeve surrounds the distal expansion ring of the stent assembly, and the second proximal enclosing sleeve surrounds the sleeve-like element thereof and the proximal expansion ring.

4. The catheter assembly as claimed in claim 2, characterized in that the first, distal enclosing sleeve surrounds the distal expansion ring and the sleeve-like element, and the second, proximal enclosing sleeve surrounds the proximal expansion ring of the stent assembly.

5. The catheter assembly as claimed in claim 1-5, characterized in that the guide wire and the first, distal enclosing sleeve each carry an element of a tension-resistant coupling.

6. The catheter assembly as claimed in claim 5, characterized in that the first element of the coupling is formed by a thickened portion, provided with a circumferential groove, on the distal end of the guide wire, and the second element of this coupling is formed by the elastically yielding end edge, which tapers toward the centre axis of the first, distal protective sleeve, of this sleeve.

7. A stent assembly for use in combination with the catheter assembly as claimed in one or more of claims 1-6, comprising two expandable support rings, which are located at a distance from one another and have an open, diamond-shaped structure, of which those points of the diamond which face one another are connected to one another by tension-resistant wires or threads which are embedded in the surface of a sleeve-like element.

8. The stent assembly as claimed in claim 7, characterized in that the sleeve-like element can perform a therapeutic action.

9. The stent assembly as claimed in claim 8, characterized in that the sleeve-like element is a medicament carrier.