WO2006003486A1

WO2006003486A1 - A device for introducing and positioning a stent in a blood vessel

Info

Publication number: WO2006003486A1
Application number: PCT/IB2005/001889
Authority: WO
Inventors: Gioacchino Coppi
Original assignee: Gama-Hs Srl
Current assignee: Gama-Hs Srl
Priority date: 2004-07-06
Filing date: 2005-07-04
Publication date: 2006-01-12
Anticipated expiration: 2007-01-06
Also published as: ITMO20040175A1

Abstract

The device comprises: a catheter (2) having a longitudinal axis (x); at least an inflatable dilating balloon (3), which is coaxial and solidly constrained to the catheter (2); a pusher element (5), solidly constrained to the catheter (2) and projecting transversally from the catheter (2); a sheath (6) in which the catheter (2) is slidably insertable, at least over a part of a length thereof.

Description

A Device for Introducing and Positioning a Stent in a Blood Vessel.

Technical Field

The device of the invention is applicable to the treatment of stenosis by application of stent-grafts.

Background Art

A stenosis is in brief a reduction of an internal section of a blood vessel which obstructs the flow of blood. If this reduction is of a considerable entity it may determine a drop in the flow rate of blood destined to reach and organ and/or it may cause an excessive increase in blood pressure upstream of the stenosis. A further risk is that of fragments' detaching and causing possible cerebral embolisms. To remove this reduction of section, caused by the presence of stenosis, and to block the detachment of the fragments, a tubular prosthesis known as a stent-graft is introduced internally of the blood vessel. The stent is positioned internally of the stenosis and is broadened to bring the original section back to normal or at least to reduce the obstruction of the vessel. The application of the stent is often accompanied by temporary cerebral protection devices.

Stent-grafts commonly used, known by the name of "self-expandable stents", exhibit considerable radial elasticity. These stents are introduced and positioned internally of the blood vessels by a device comprising a bearing catheter and an external sheath. The stent is coaxial to the catheter and located internally of the sheath, and is freed by drawing back the sheath from the catheter. The catheter is provided with a pusher, which blocks the stent when the external sheath is slid back. When the sheath is removed the stent is progressively freed and expands radially, easing itself onto the wall of the treated blood vessel. The elastic radial force which dilates the stent is generally not sufficient to dilate the stenosis, so that the stent tends to take on an egg-timer shape in which it imitates the stenosis' shape while reaching the vessel wall up- and downstream of the stenosis. When the stent is freed the catheter used for its application must be extracted, and another catheter introduced which is provided with an inflatable balloon for dilating the stenosis. By means of the second catheter the balloon is positioned and inflated internally of the stent. This part of the procedure is called post- dilation and is the most risky stage of the operation due to the possible embolisms that might be caused by the stenosis.

The introduction of the catheter bearing the stent follows the introduction into the blood vessel of a guide wire on which the catheter slides thanks to a longitudinal channel passing through the catheter. The guide wire traces the path the catheter must follow, facilitating its moving around curves, bends and so on along the blood vessel.

If the stenosis is very pronounced, use of a further catheter is required, one including a further inflatable balloon. The function of the balloon is to perform a pre-dilation of the stenosis which is sufficient to enable the passage of the external sheath comprising the stent.

The devices of known type, therefore, require a certain number of introduction and extraction manoeuvres, involving at least two catheters and the guide wire; all of this contributes to increasing operation times and risk of embolism. The main aim of the present invention is to provide a device for introducing and positioning stent grafts in blood vessels, which obviates the drawbacks of known-type devices.

Disclosure of Invention Further characteristics and advantages of the device will better emerge from the detailed description that follows, made with reference to the appended figures of the drawings, which are intended as non-limiting examples, in which:

Figure 1 is an overall view in partial section of a device according to the present invention;

Figure 2 is the device of figure 1 in a first operative configuration relating to a first stage of use;

Figure 3 shows the device of figure 1 in a second operative configuration relating to a second stage of use; Figure 4 shows the device of figure 1 in a third operative configuration relating to a third stage of use;

Figure 5 shows the device of figure 1 in a fourth operative configuration relating to a fourth stage of use;

Figure 6 shows an enlarged detail in section of the device of figure 1; Figure 7 shows a detail relating to a further embodiment of the device of figure 1.

With reference to the figures of the drawings, the device for introducing and positioning stents in blood vessels of the present invention comprises a catheter 2, having a longitudinal axis x, and at least a dilating balloon 3, coaxial and solidly constrained to the catheter 2. The catheter 2 is constituted by a slim and flexible cylindrical element, suitable for inserting into a blood vessel. The dilating balloon 3 is fixed in a predetermined position along the catheter 2; in an inflated configuration, the balloon has a tubular form which is cylindrical and coaxial to the catheter 2.

The device of the present invention further comprises at least a pusher element 5, solidly constrained to the catheter 2, and a sheath 6 in which the catheter 2 is slidably inserted at least over a part of its length.

The sheath 6 is constituted by a tubular cylindrical element predisposed to contain internally thereof at least a portion of the catheter 2 and a stent 20 to be introduced into a blood vessel. The stent 20 is arranged coaxially to the catheter 2, in contact with the pusher element 5, internally of the sheath 6. In a suitable configuration for the introduction of the device into a blood vessel, the sheath 6 internally contains a portion of catheter 2 and the stent 20. A portion of the catheter 2 projects externally of the sheath 6. In a preferred embodiment, illustrated in the accompanying figures of the drawings, the device comprises a pre-dilating balloon 7, coaxial and solidly constrained to the catheter 2, which, in an inflated position, exhibits a tubular and cylindrical form, coaxial to the catheter 2. In an inflated configuration of both balloons, the pre-dilating balloon 7 exhibits a smaller diameter than the dilating balloon 3. In the preferred embodiment, the catheter 2 exhibits at least a guide portion 2a arranged at an end thereof. The guide portion 2a is made of a material having greater flexibility with respect to the material the catheter 2 is made of. The greater flexibility of the portion of guide 2a facilitates the passage of the catheter through the bends of the blood vessel and across the stenosis. At the opposite end with respect to the guide portion 2a, the catheter 2 is provided with a manoeuvring portion, of known type and not illustrated in the figures, which is predisposed to facilitate the manipulation and advancement and extraction manoeuvres from the blood vessel. Similarly, the sheath 6 exhibits a manoeuvring portion arranged at the end which remains external of the blood vessel.

The dilating balloon 3 and the predilating balloon 7 are arranged in proximity of the guide portion 2a. In more detail, the predilating balloon 7 is closer to guide portion, while the dilating balloon 3 is arranged upstream of the dilating balloon 3, that is by the side of the predilating balloon 7 on the opposite side with respect to the guide portion 2a. The stent 20 can be arranged coaxially to the dilating balloon 3, or can be arranged in a space, predisposed for the purpose, comprised between the predilating balloon 7 and the dilating balloon 3. A further possibility is that the stent is arranged on the opposite side from the dilating balloon 3 with respect to the predilating balloon 7. The dilating balloon 3 is inflatable by first inflating means which comprise at least a first channel 4, afforded internally of the catheter 2, which at a first end is in communication with the inside of the dilating balloon 3, and at a second end is associable with a pressurised fluid source. The second end of the first channel 4 can be associated, for example to a hand pump, through which pressurised air can be sent internally of the dilating balloon 3 in order to inflate it. The deflating of the balloon can be achieved through the second end of the first channel 4. The predilating balloon 7 is inflatable by second inflating means which comprise at least a second channel 8, afforded internally of the catheter 2, which at a first end is in communication with the inside of the predilating balloon 7 and at the other end is associable to a pressurised fluid source. In the preferred embodiment of the device the first channel 4 and the second channel 8 constitute a single channel for the inflation of the dilating balloon 3 and the predilating balloon. 7. The single channel is provided with a first opening in communication with the inside of the dilating balloon 3, a second opening in communication with the inside of the predilating balloon 7 and an end through which the single channel is associable to a source of pressurised fluid. In further embodiments the first channel 4 and the second channel 8 can be discrete in order to enable an independent inflation of the two balloons. The device is introduced into the blood vessel through the skin, firstly by the guide portion 2a and is pushed towards the stenosis, to where the stent 20 is to be positioned. During the introduction of the device, the sheath 6 moves in constraint with the catheter 2 and is positioned so that it internally contains the stent 20. The device is provided with means of known type for fastening the sheath 6 to the catheter 2.

If the stenosis is particularly large, the passage of the sheath 6 containing the stent 20 can be eased by the predilating balloon 7, which can be positioned and inflated internally of the stenosis so as at least partially to dilate it. In the inflated configuration the predilating balloon 7 has a greater diameter than the external diameter of the sheath 6, thus guaranteeing a widening of the stenosis which is sufficient to enable the passage of the sheath 6. The device is advanced up until the stent 20 is positioned internally of the stenosis. At this point, while the catheter 2 is held in position by its manoeuvring end, the sheath 6 is made to slide in an extraction direction from the blood vessel. The stent 20 is positioned in contact with the pusher element 5 solidly constrained to the catheter 2, and thus remains still with respect to the sliding of the sheath 6 and is progressively freed. The stent 20, by elastically dilating in a radial direction, comes into contact with the walls of the vessel and the stenosis. If the elastic expansion of the stent 20 is not sufficient to dilate the stenosis to the desired extent, the dilating balloon 3 can be positioned and inflated internally of the stent 20. If the dilating balloon 3 is arranged internally of the stent 20, the manoeuvre can be performed directly, otherwise it will be necessary to displace the catheter 2, either advancing or retreating it according to the position of the dilating balloon 3 with respect to the stent 20, which brings the dilating balloon 3 internally of the stent 20. The functions of predilating and dilating of the stenosis can be performed by a single balloon. In this case the device takes on a minimum embodiment in which it comprises the catheter 2, the dilating balloon 3, the pusher element 5 and the sheath 6. During the introduction of the device it is sufficient for the sheath 6 to contain internally only the stent 20, while the balloon can remain external of the sheath 6. Also in the embodiment comprising two balloons, if they are separately inflatable the sheath 6 can contain only the stent 20, while the two balloons can be arranged on the portion of catheter 2 which projects from the sheath 6.

In a further embodiment the catheter 2 exhibits a longitudinal through- channel 9 predisposed for insertion of an external guide wire 21. The use of an external guide wire can be necessary in cases where the blood vessel is particularly bendy and full of obstacles, should the presence of the guide portion 2a of the catheter 2 not be sufficient to guarantee correct movement of the device. The device of the present invention offers important advantages. Firstly, the introduction and positioning of the stent are done in a single manoeuvre. The device comprises all of the necessary elements: the guide portion for facilitating the advancing of the device internally of the vessel, the predilating balloon for facilitating passage of the sheath through the stenosis, the dilating balloon for radially widening the stent up until the original section of the blood vessel is achieved. The device thus limits risks of embolisms due to the various manoeuvres of introduction and extraction which are necessary with devices of known type, and further enables an increase in rapidity of the operation. The extreme rapidity of the operation further enables the use of a technique which further limits the risk of embolisms. This technique consists in completely blocking the blood flow upstream and downstream of the stenosis, isolating the parts of the vessel where the stent graft is to be positioned, and aspirating any eventual thrombi and embolisms. This technique is the one which limits best of all the risk of embolisms and is not practicable if the operation time is excessive, as is the case when the stent graft is done using devices of known type.

Claims

Claims.

1). A device for introducing and positioning a stent in a blood vessel, wherein it comprises: a catheter (2) having a longitudinal axis (x); at least an inflatable dilating balloon (3), coaxial and solidly constrained to the catheter

(2); a pusher element (5), solidly constrained to the catheter (2) and projecting transversally from the catheter (2); a sheath (6) in which the catheter (2) is slidably insertable at least for a part of a length thereof.

2). The device of claim 1, wherein it comprises an inflatable predilating balloon (7), which is coaxial and solidly constrained to the catheter (2).

3). The device of claim 2, wherein in an inflated configuration both balloons exhibit a tubular cylindrical shape and are coaxial to the catheter (2), the predilating balloon (7) having a smaller diameter than the dilating balloon (3).

4). The device of any one of the preceding claims, wherein the catheter (2) exhibits at least a guide portion (2a) arranged at an end of the catheter (2).

5). The device of claim 1, wherein the dilating balloon (3) is arranged in proximity of the guide portion (2a).

6). The device of claim 2, wherein the predilating balloon (7) is arranged in proximity of the guide portion (2a).

7). The device of any one of the preceding claims, wherein the catheter (2) exhibits a longitudinal through-channel (9).

8). The device of claim 1, wherein it comprises first means for inflating the dilating balloon (3) which first means comprise at least a first channel (4), afforded internally of the catheter (2) which at an end thereof is in communication with an inside of the dilator balloon (3), and at another end thereof is associable to a source of pressurised fluid. 9). The device of claim 2, wherein it comprises second means for inflating the predilating balloon (7) which means for inflating comprise at least a second channel (8), afforded internally of the catheter (2), which at an end thereof is in communication with an inside of the predilating balloon (7) and at another end thereof is associable to a source of pressurised fluid. 10). The device of claim 8 or 9, wherein the first channel (4) and the second channel (8) constitute a single channel for inflating the dilating balloon (3) and the predilating balloon (7), the single channel being provided with a first opening in communication with an inside of the dilating balloon (3), a second opening in communication with an inside of the predilating balloon (7) and an end with which it is associable to a source of pressured fluid. 11). The device of claim 1, wherein the sheath (6) is constituted by a cylindrical tubular element predisposed to contain internally thereof at least a portion of the catheter (2) and a stent (20) arranged coaxially of the catheter (2).