SELF-EXTENDABLE STENT FOR PULMONARY ARTERY

Abstract

The invention relates to a self-expandable stent, especially a pulmonary stent, with a proximal section, a middle section and a distal section arranged at a longitudinal axis of the stent, the stent having a dry valve made of bovine pericardium arranged at the middle section thereof, a skirt surrounding the dry valve at least at the middle section and made of one of bovine pericardium and polyester, wherein the stent further comprises eyelets arranged at a distal end at the distal section and/or a proximal end at the proximal section for fixing the stent at an artery, and wherein the stent comprises a frame composed of a plurality of arms forming the proximal, the middle and the distal section with the sections being interconnected, and the stent comprising a fixture area at the middle section of the frame with the arms being arranged in parallel to each other at the fixture area and the middle section comprising one or more fixture openings at said fixture area for fixing the valve at the frame. The invention further relates to A delivery device for delivering a self-expandable stent according to claims 1 to 14, the delivery device comprising a flush port, a main body part for holding, inflating and/or releasing the stent, and an actuation mechanism for moving the stent to a delivery site, and/or wherein the actuation mechanism has a torque control and can rotate the stent about an axis of the main body, and/or the delivery device having a knob or the like at the actuation mechanism, with the knob in particular being able to be rotated about an axis of rotation of the actuation mechanism.

Claims

1. A self-expandable stent with a proximal section, a middle section and a distal section arranged at a longitudinal axis of the stent, the stent having a dry valve made of bovine pericardium arranged at the middle section thereof, a skirt surrounding the dry valve at least at the middle section, the skirt comprising at least one of bovine pericardium and polyester, wherein the stent further comprises eyelets arranged at at least one of a distal end of the distal section and a proximal end of the proximal section for fixing the stent at an artery, and wherein the stent comprises a frame composed of a plurality of arms forming the proximal section, the middle section and the distal section with the sections being interconnected, and the stent comprising a fixture area at the middle section of the frame with the arms being arranged in parallel to each other at the fixture area and the middle section comprising one or more fixture openings at said fixture area for fixing the valve at the frame.

2. The self-expandable stent according to claim 1, wherein the middle section comprises a length which is approximately 5 to 30% of a total length of the stent.

3. The self-expendable stent according to claim 1, wherein one or more such openings are provided in one or more arms of the middle section.

4. The self-expendable stent according to claim wherein two or more such openings are provided in one or more arms of the middle section.

5. The self-expandable stent according to claim 1, wherein the dry bovine pericardium has a maximum tensile stress selected in the range of 20 to 25 MPa.

6. The self-expandable stent according to claim 1, wherein the rehydrated bovine pericardium has a tensile stress selected in the range of 12 to 15 MPa.

7. The self-expandable stent according to claim 1, wherein the dry bovine pericardium has a calcium content selected in the range of 0.01 to g/Kg.

8. The self-expandable stent according to claim 1, wherein the dry valve comprises between two and six leaflets.

9. The self-expandable stent according to claim 1, wherein the dry valve comprises three or four leaflets.

10. The self-expandable stent according to claim 1, wherein the dry bovine pericardium is formed by using a method of treatment comprising the following steps: soaking of the bovine pericardium treated with a crosslinking agent with a saline solution; contacting the soaked bovine pericardium with an aqueous solution comprising Hydrogen Peroxide; contacting the bovine pericardium with an aqueous solution comprising PBS and EDTA; contacting the bovine pericardium with a solution comprising glycerol, ethanol and EDTA; and contacting the bovine pericardium with a glycerol solution.

11. The self-expandable stent according to claim 1, wherein, in the expanded state, a maximum outer diameter of the proximal section is larger than a maximum outer diameter of the middle section and a maximum outer diameter of the distal section.

12. The self-expandable stent according to claim 1, wherein, in the expanded state, a minimum outer diameter of the stent is present at the fixture area, wherein the fixture area has an at least substantially cylindrical shape respectively a cylindrical shape over a length of the fixture area along the longitudinal axis.

13. The self-expandable stent according to claim 12, wherein the length of the fixture area is equal to a length of the middle section.

14. The self-expandable stent according to claim 1, wherein the skirt is arranged to cover the middle section at least from within the middle section, and parts of the proximal section and optionally parts of the distal section.

15. The self-expandable stent according to claim 14, wherein the skirt is arranged to cover the middle section within the fixture area.

16. The self-expandable stent according to claim 14, wherein the skirt is arranged to cover at most 50% of the distal section and 100% of the middle section.

17. The self-expandable stent according to claim 16, wherein the skirt is arranged to cover between 20% and 100% of the proximal section.

18. The self-expandable stent according to claim 1, wherein all of the ends of the arms at the distal and the proximal ends lie in a common plane.

19. The self-expandable stent according to claim 18, with the eyelets of the proximal end projecting beyond the common plane at the ends of the arms.

20. The self-expandable stent according to claim 19, wherein the eyelets lie in a further common plane.

21. The self-expandable stent according to claim 1, wherein the ends of the arms of the frame at the proximal and/or the distal end are arranged coaxially with the longitudinal axis.

22. The self-expendable stent according to claim 1, wherein lines extending from proximal end to the distal end from the ends of the arms respectively the eyelets taper towards the distal end.

23. A delivery device for delivering a self-expandable stent, the self-expandable stent having a proximal section, a middle section and a distal section arranged at a longitudinal axis of the stent, the stent having a dry valve made of bovine pericardium arranged at the middle section thereof, a skirt surrounding the dry valve at least at the middle section, the skirt comprising at least one of bovine pericardium and polyester, wherein the stent further comprises eyelets arranged at at least one of a distal end of the distal section and a proximal end of the proximal section for fixing the stent at an artery, and wherein the stent comprises a frame composed of a plurality of arms forming the proximal section, the middle section and the distal section with the sections being interconnected, and the stent comprising a fixture area at the middle section of the frame with the arms being arranged in parallel to each other at the fixture area and the middle section comprising one or more fixture openings at said fixture area for fixing the valve at the frame, the delivery device comprising a flush port; a main body part for holding, inflating and/or releasing the stent; and an actuation mechanism for moving the stent to a delivery site, and/or wherein the actuation mechanism has a torque control and can rotate the stent about an axis of the main body, and/or the delivery device having a knob or the like at the actuation mechanism, with the knob in particular being able to be rotated about an axis of rotation of the actuation mechanise.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0078] The patent or application file contains at least one drawing executed in color. Copies of this patent or patent application publication with color drawing(s) will be provided by the Office upon request and payment of the necessary fee.

[0079] The invention will be described in detail by means of embodiments and with reference to the drawings. These show preferred embodiments. The features described may be configured in various combinations, which are encompassed in this document. The drawings show:

[0080] FIG. 1: an exemplary stent frame;

[0081] FIG. 2: an exemplary stent frame including a valve and a skirt;

[0082] FIG. 3: different stents of different sizes;

[0083] FIG. 4: a CT reconstruction picture of a stent according to the invention inserted in a patient's artery;

[0084] FIG. 5: the CT reconstruction picture of FIG. 4 at a different angle;

[0085] FIG. 6: the CT reconstruction picture of FIGS. 4 and 5 at another angle; and

[0086] FIG. 7: a delivery device for delivering a self-expandable stent,

DETAILED DESCRIPTION

[0087] FIG. 1 shows a self-expandable stent 10 configured to be placed in the pulmonary artery of a patient. The stent 10 comprises a frame 12 which is composed of a plurality of arms 14 fabricated of Nitinol. Nitinol is a flexible metal, which comprises the characteristic of being self-expandable. Hence, the stent 10 can be delivered in a compressed state to a point of interest such as the pulmonary artery of a human, where it can self-expand once it is deployed.

[0088] The frame 12 further comprises three sections, i.e. a proximal section PS, a middle section MS and a distal section DS, which are all interconnected with each other. The proximal section PS is characterized by comprising the proximal end PE of the stent 10, i. e, said end, which is closer to the heart once the stent is put in place. Consequently, the distal section DS comprises a distal end DE, which is farther away from the heart once the stent is fixed at the pulmonary artery. The middle section MS is arranged between the proximal and the distal section PS, DS.

[0089] The middle section MS further includes a valve 16 made out of dry bovine pericardium as well as skirt 18 made out of dry bovine pericardium and polyester (FIG. 2). FIG. 2 also shows the leaflets 20 of the valve 16. The valve 16 can comprise between 2 and 6 leaflets, preferably 3 or 4 leaflets. The characteristics of the skirt 18 will be explained below.

[0090] In order to be able to attach the valve 16 to the arms 14, the frame comprises at its middle section a fixation area 22 including several fixation openings 24. Said fixation openings 24 can be used to suture the valve 16 to the respective arms 14. As one can see, the arms 14 at said fixation area 22 are arranged in a parallel manner while at the other sections, e, g, the distal and the proximal section DS, PS, the arms 14 are arranged such that they form a net with diamond-shaped openings. As can be seen, for example, in FIG. 1 the area of the diamond-shaped openings is usually larger when the diameter of the stent 10 is bigger.

[0091] In the example shown in FIG. 1, one arm 14 comprises three openings 24 at which the valve 16 can be fixed. It may also be possible that every arm 14 or every second arm 14 or maybe only as many arms 14 as leaflets 20 comprise a fixation area 22 with respective fixation openings 24. In another example (not shown) it may also be possible that the fixation openings 24 are arranged at a bridge, connecting two adjacent arms 14 at the fixation area 22 such that the fixation openings 24 are arranged between two adjacent arms 14.

[0092] Due to anatomical reasons of the pulmonary artery and the right ventricle of a heart,the skirt 18 of the stent 10 does not only surround the valve 16 at the fixation area 22 but also up to 100% of the proximal section PS (see FIG. 2) or at least parts of the proximal section PS (see FIG. 3) to prevent leakage between the stent 10 and the ventricle of the patient's heart. Furthermore, the skirt 18 can also cover parts of the distal section DS, which can be seen in FIGS. 2 and 3. Thus, the skirt 18 can cover up to 50% of the distal section DS, between 20 and 100% of the proximal section PS and 100% of the middle section MS.

[0093] In order to being able to attach the stent 10 at its respective point of interest, i. e. the pulmonary artery, the stent 10 comprises eyelets 26 at its respective proximal and/or distal end PE, DE (see e. g. FIG. 3). That is, after being expanded, the stent 10 does not only hold itself in place by fitting into the pulmonary artery but also by being sutured. This way, it may also be possible to attach the proximal end PE of the stent 10 at the transition of the pulmonary artery and the right ventricle of a heart or at the wall of the right ventricle itself such that the stent 10 protrudes inside the ventricle. The exact attachment point and technique can thus be chosen according to the different conditions at the different hearts which are being treated with the invention.

[0094] As one can see especially in FIGS. 1 to 3, the stent 10 comprises different diameters at its different sections. The middle section MS which comprises at least the fixation area 22 comprises the smallest diameter. This way, a compression of the coronary arteries, which wrap the whole heart, can be prevented.

[0095] The diameters of the proximal and the distal ends PE, DE are therefore larger. It may be possible that said two diameters are of the same size. In most embodiments it has shown that it can be advantageous to choose the diameters such that the proximal end PE comprises a larger diameter than the distal end DE such that lines, which connect the ends 28 of the arms 14 of the proximal end PE with the ends 30 of the arms at the distal end DE taper. The reason for this is that at the proximal end PE the stent 10 can protrude inside the ventricle of the heart. Therefore the diameter of said end needs to large enough such that it can be sutured to the hearts wall or at least seals the transition between the ventricle and the pulmonary artery sufficiently.

[0096] The ends 28, 30 of the arms 14 at both ends of the stent 10 can lie in a common plane. Furthermore, the ends 28, 30 of the arms 14 of the frame 12 at the proximal and the distal end PE, DE are arranged coaxially with the longitudinal axis A of the frame 12, The eyelets 26, which are used to suture the stent 10 to the artery project beyond said plane (see esp. at the proximal end PE in FIG. 3). Said eyelets 26 can comprise a rectangular outer shape with a rectangular opening for suturing the stent 10 to the pulmonary artery. Generally, those eyelets 26 can also comprise a different shape, e. g. a circular shape, for both the outer and the inner shape.

[0097] FIG. 3 shows a delivery device 32 for the self-expandable stent 10 also known as a catheter. The delivery device 32 comprises a flush port 34 for flushing internal cavities of the delivery device (not shown) and a main body 36 for holding, inflating and/or releasing the stent 10. The device may further comprise two valved introducers (not shown) to allow access to the stent 10. Initially two diagnostic catheters (not shown) can be introduced via said two valved introducers together with the preloaded stent for delivering the stent to the target delivery site, i.e, the patients' heart.

[0098] The delivery device 32 further includes an actuation mechanism 40 for moving the stent 10 to a delivery site.

[0099] The main body 36 is arranged at an inner shaft at an end of the lumen 38 that extends between the actuation mechanism 40 and a tip 42 of the catheter. The stent 10 can thus be guided to the delivery site by means of the actuation mechanism 40 that has a torque control and can rotate the stent 10 about an axis A of the frame 12. The (longitudinal) axis A extends between the proximal and the distal end PE, DE of the frame 12 of the stent 10.

[0100] The actuation mechanism 40 comprises a knob 44 at a distal end 50 of the actuation mechanism 40. On turning the knob 44 about an axis B of the actuation mechanism 40 which extends between the distal end 50 and a proximal end 52 of the actuation mechanism 40, the lumen 38 is able to deflect. This enables the tip 42 of the lumen 38 to occupy various positions (not shown). Such a deflection of the lumen 38 reduces the overall stress in the system which leads to a better positioning of the stent 10 at a delivery site and an overall improved accuracy of deployment of the delivery device 32 and hence of a stent 10 that is delivered to a delivery site using the delivery device 32.

[0101] On delivering the stent 10 to the delivery site, i.e. the heart, by means of the delivery device 32, the arterial femoral access is preferably used. The lumen 38 is then moved through the arteries to the heart.

[0102] The position of the stent 10, the diagnostic catheters and/or of the delivery device 30 may be tracked using e.g. x-rays in order to monitor radiopaque markings present at the stent 10 and/or the delivery device 30. Thereby the precision and accuracy during deployment of the stent 10 within the heart can be further increased, so that the replacement valve 16 can be positioned accurately at the aortic valve.

[0103] In FIGS. 4 to 6 one can see different MRI pictures of a stent 10, which has been deployed at the pulmonary artery of a patient, preferably by a delivery device 32 according to the invention. The different pictures in FIGS. 4 to 6 show the same stent 10 from different angles. As one can see in those MRI pictures, the stent 10 is in the expanded state and has been deployed at the transition between the pulmonary artery and the right ventricle of the patient.