Biodegradable metallic vascular stent and application thereof

Abstract

A biodegradable metallic vascular stent includes: a base body which is tubular with a lumen along a longitudinal axis, wherein the base body has a plurality of circumferential support structures which are successively positioned along the longitudinal axis. The circumferential support structures are each composed of a sequence of repeat units and has two or more connectors, wherein two adjacent circumferential support structures are joined together by at least one of the connectors, and each of the connectors is attached to one of arched elements in the repeat units of the two adjacent circumferential support structures to be connected. The biodegradable metallic vascular stent possesses suited radial pressure, flexibility and fatigue strength. Furthermore, the stent is design for peripheral vascular disease and coronary artery disease treatment as well.

Claims

1. A biodegradable metallic vascular stent, comprising a base body which is tubular with a lumen along a longitudinal axis, wherein the base body has a plurality of circumferential support structures which are successively positioned along the longitudinal axis and are each composed of a sequence of repeat units, and each of the circumferential support structures connects to two or more connectors, wherein two adjacent circumferential support structures are joined together by at least one of the connectors, and each of the connectors is attached to one of arched elements of the two adjacent circumferential support structures to be connected; wherein for the base body, an outer diameter is between 1 mm and 5 mm, a thickness in a radial direction is between 0.1 mm and 0.3 mm, a length in a longitudinal direction is between 10 mm and 100 mm; wherein for the circumferential support structures, a width of the arched elements is between 0.1 mm and 0.3 mm, a width of diagonal elements is between 0.06 mm and 0.25 mm; wherein for the connectors, a radius of a middle line of curved elements is between 0.10 mm and 0.30 mm.

2. The biodegradable metallic vascular stent as defined by claim 1, wherein the biodegradable metallic vascular stent is applicable to treatment of a peripheral vascular disease and a coronary artery disease.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) By reading the following detailed description of non-limiting embodiments given with reference to the following drawings, the features, objects and advantages will become more apparent:

(2) FIG. 1 shows a computer simulation illustration depicting a perspective view of an embodiment of a biodegradable stent.

(3) FIG. 2 shows a planar view of a stent scaffold embodiment.

(4) FIG. 3 shows the detailed shape of repeat unit in an embodiment.

(5) FIG. 4 shows the detailed shape of connector in an embodiment.

(6) Element reference: 1repeat unit; 2connector; 3circumferential support structure; 11bump element; 12arched element; 13diagonal element; 14kink element; 21curved element; 22straight portion.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

(7) It will be apparent to those skilled in the art that numerous modifications and variations of the described examples and embodiments are possible in light of the above teaching. The disclosed examples and embodiments are presented for purposes of illustration only. Therefore, it is the intent to cover all such modifications and alternate embodiments as may come within the true scope of this invention.

Embodiment 1

(8) The present disclosure provides an example embodiment 1 of a biodegradable stent shown in FIG. 1, comprising a base body which is tubular with a lumen along a longitudinal axis, wherein the base body has a plurality of circumferential support structures 3 which are successively positioned along the longitudinal axis and are each composed of a sequence of repeat units 1; and each of the circumferential support structures has two or more connectors 2, wherein two adjacent circumferential support structures 3 are joined together by at least two of the connector 2, and each of the connectors 2 is attached to one of arched elements 12 of the two adjacent circumferential support structures 3 to be connected.

(9) According to embodiment 1, the adjacent circumferential support structures 3 are specularly symmetric.

(10) FIG. 4 shows the connectors 2, which are n shaped and comprise curved elements 21 and two straight elements 22; outer contours of curved element 21 are smooth curve-shaped, and inner contours are symmetric intersection of smooth curves.

(11) As shown in FIG. 1, a quantity of the repeat units in each of the circumferential support structures 3 is between 4 and 8. In the embodiment 1, the quantity is 6; the connectors 2 are spiral distribution in a longitudinal direction; a quantity of the connectors 2 between the two adjacent circumferential support structures 3 to be connected is between 2 and 4. In the embodiment 1, the number is 3.

(12) FIG. 2 shows the detail shape of the repeat units 1, which is the repeat units 1 of the circumferential support structures 3. Specifically, the repeat units 1 are each composed of the sequence of the arched elements 12, diagonal elements 13 and kink elements 14; the diagonal elements 13 are symmetrical located at both side of the arched elements 12, wherein two of the diagonal elements 13 are joined together by one of the kink elements 14.

(13) There is a bump element 11 at a center of the outer contour of each of the arched elements; a height of the bump elements 11 is between 0.01 mm and 1 mm; a major axis of the arched elements 12 is between 0.1 mm and 0.5 mm, a minor axis of the arched elements 12 is between 0.05 mm and 0.40 mm.

(14) As shown in FIG. 1, an out diameter of the stent is between 1 mm and 5 mm, a thickness in a radial direction is between 0.1 mm and 0.3 mm, a length in a longitudinal direction is between 10 mm and 100 mm; wherein for the circumferential support structures 3, a width of the arched elements 12 is between 0.1 mm and 0.3 mm, a width of the diagonal elements 13 is between 0.06 mm and 0.25 mm; wherein for the connectors 2, a radius of a middle line of the curved elements 21 is between 0.10 mm and 0.30 mm.

(15) Stent coating function to deliver anti-proliferative drugs, increase device biocompatibility and decrease the corrosion rate of Mg stent. The coating must also have suitable mechanical properties such that occurrences of delamination and fracture during stent crimping and implantation are eliminated. Owing to the homogeneous distribution of plastic deformation in the stent during crimping and balloon expansion, the stress and traction concentration of polymer coating reduced a lot and the integrity of coating is guaranteed. Furthermore, the corrosion fatigue performance of stent is improved.

(16) The base body of the stent according to one invention embodiment may be composed of any biodegradable implant material that is suitable for the manufacture of implants, in particular stent. Biodegradable materials for stent include (but are not limited to) magnesium-based alloys and zinc-based alloys.

Embodiment 2

(17) In an alternative embodiment 2 of the present invention, the quantity of the repeat units 1 in each of the circumferential support structures 3 is between 4 and 8; the connectors 2 are spiral distribution in the longitudinal direction; the quantity of the connectors 2 between the two circumferential support structures 3 to be connected is between 2 and 4. Other composition and connection are same as the embodiment 1. By the means of increasing or decreasing the quantity of repeat units, the out diameter of stent can be resized in a large scale.

Embodiment 3

(18) In an alternative embodiment 3 of the present invention, the height of the bump elements 11 is between 0.01 mm and 0.06 mm; the major axis of the arched elements 12 is between 0.15 mm and 0.35 mm, the minor axis of the arched elements 12 is between 0.10 mm and 0.30 mm, the width of the strut is between 0.10 mm and 0.20 mm. Other composition and connection are same as the embodiment 1.

Embodiment 4

(19) In an alternative embodiment 4 of the present invention, the out diameter of the stent is between 1 mm and 5 mm, the thickness in the radial direction is between 0.1 mm and 0.2 mm, and the length in the longitudinal direction is between 50 mm and 100 mm. Other composition and connection are same as the embodiment 1.

Embodiment 5

(20) In an alternative embodiment 5 of the present invention, as a result of introduction of the kink elements 14, the arched elements 12 could modified to larger radius and take more space during crimped status. Therefore, a homogeneous distribution of stress and plastic deformation in the arched elements of the stent are accomplished. The maximus principal stress and maximus residual stress reduced 5.2% and 7.6% separately, because of the benefit of the kink elements and un-uniform radius arched elements.