Self-expanding endovascular stent (and its variants)

 

The invention relates to medicine and, in particular, to devices used in endovascular surgery to restore the modified sections of blood vessels and other hollow tubular organs. In the first embodiment, the stent is made of metal zigzag bent wire forming a cylindrical surface. Wire made of cobaltreciprocating alloy “Plastocrete-08 and has a rectangular with rounded corners in cross-section. The stent has the form of at least one section, in which the zigzag wire is directed along the longitudinal axis of the stent and have a deflection inside the stent. In the second embodiment, the stent is made of a zigzag bent wire forming a cylindrical surface. Wire made of cobaltreciprocating alloy “Plastocrete-08 and has a rectangular with rounded corners in cross-section. Zigzags made in the form of elements of the rhombic shape with rounded corners, and a large diagonal of a rhombus is directed at an angle of 0-90to the longitudinal axis of the stent. Technical result - improved biological compatibility and ensure maximum adaptation of the stent to the wall of a hollow organ. 2 N. p. is namely devices, used in endovascular surgery to restore the modified sections of the lumen of blood vessels or other hollow tubular organs. To restore and maintain the lumen of hollow organs with stenosis and occlusion of vessels by mechanical compression and tumor obstruction of hollow organs are used self-expanding endovascular stents, made of metal wire.

Known self-healing stent for vessels and hollow organs, made of nitinol wire in the form of a mesh cylindrical surface with cells rhombic, with cells made in the form of a longer shaft than crossbar diamond, large diagonal of a rhombus is located along the longitudinal axis of the stent, and all elements of the cells form the minimum angles with the axis of blood flow that maintains laminar flow of blood in the vessel {Russian Federation patent No. 2121317, MKI6A 61 F 2/06 published 10.11.98}. At the ends of the stent is made of radiopaque labels because the alloy nitinol has a low use of rotary instruments. The stent is made of nitinol wire of circular cross section, has good biological compatibility, and minimal invasiveness. However, the rigidity of the ETA of the vessel or hollow organ. In addition, the nitinol is an expensive alloy, which is reflected in the cost of manufactured stents.

The closest to the essential features of the claimed stent is self-expanding endovascular stent made of zigzag curved metal wire in the form of a cylindrical hollow body (U.S. patent No. 5800456, MKI6A 61 M 29/00, published 01.09.98). The stent is made of wire of circular cross section, made of stainless steel. On the vertices of the zigzags formed round “eyes”, part of which is sealed with the formation of the ring. Zigzag blank is formed into a tube in a spiral; through the “eyes” progenote thread connecting structure. The thread is also posted in a spiral. The length of the straight sections in zigzags, located at the ends of the stent varies from 9 to 17 mm This gradually increasing the length of the straight sections leads to the fact that the cross section of the stent at the ends perpendicular to its axis in spite of the spiral arrangement of the workpiece. The stent can be compressed along the axis and expands after installation in a blood vessel or other hollow organ, and it is characterized homogeneous expanding “rigidity” in length.

However, the constant stiffness on the moreover, wire made of stainless steel, has a relatively low corrosion resistance and low index of biocompatibility.

The technical problem on which the invention is directed, is to improve the biocompatibility of the stent and the manufacture of the stent with variable stiffness along the length that provides maximum adaptation of the stent to the wall of a blood vessel or other hollow organ.

The specified technical task is solved in that the self-expanding endovascular stent made of metal zigzag bent wire forming a cylindrical surface, made of wire, made of cobaltreciprocating alloy (Plastocrete-08) and rectangular with rounded corners, the cross-section, and the stent has the form of at least one cylindrical section, in which the zigzag wire is directed along the longitudinal axis of the stent and have a deflection inside the stent (the first option).

The number of sections of cylindrical shape, slightly concave on the inside, the stent can be from 1 to 10.

In the case where sections in more than one stent, the sections are fastened together by at least one fastening representing with the ribbed on the outside of the stent.

The number of V - periods in one cylindrical section of the stent can be 6-8.

Due to the deflection of zigzags inside of the stent longitudinal profile section has a shape close to a trapezoid.

The technical problem is solved also by the fact that self-expanding endovascular stent made of metal zigzag bent wire forming a cylindrical body, made of wire, made of cobaltreciprocating alloy “Plastocrete-08 and rectangular with rounded corners section, and zigzags made in the form of elements of the rhombic shape with rounded corners, and a large diagonal of a rhombus is directed at an angle of 0-90to the longitudinal axis of the stent (the second option).

For the manufacture of the stent in the first embodiment of the workpiece from zigzag curved wire is wrapped around the mandrel, the ends of the link, and the resulting partition is slightly prohibit inside. For the manufacture of multi-section stent sections connect one or two rectilinear stripes, ribbed on the outside of the stent.

The stent is formed on the second version of the continuous winding curved elements rhombic wire on the mandrel.

also to 0.05 wt.% manganese, to 0.4 wt.% carbon, up to 0.05 wt.% of aluminum, not more than 0.05 wt.% silicon and not more than 0.05 wt.% titanium (patent of Ukraine №24523, MKI6A 61 K 6/04, published 30.10.98, Bulletin No. 5). It was used for manufacturing one-piece fixed and removable dentures.

For the manufacture of self-expanding endovascular stents alloy “Plastocrete-08” still not used.

We have conducted comparative tests, the wire diameter of 0.3 mm, made of “Plastocrete-08” and a wire of the same diameter, made of stainless steel AISI 316Z and alloy nitinol. The test results presented in the table.

As can be seen from the table, “Plastocrete-0,8 has high physical and mechanical properties, high corrosion resistance, biocompatibility and rentgencontrastnomu.

The thickness of the wire, which are made of the inventive stents may be in the range from 30 to 200 microns (0.03 to 0.20 mm); the width is in the range from 75 to 390 μm (0,075 - 0,390 mm).

The diameter of the stent in the expanded state can be from 5 to 25 mm For installation inside of hollow organs with delivering device of the inventive stents may be compressed to a diameter which previews option can be 3-60 mm The minimum length of a stent according to the second variant is limited to the size of a small diagonal element rhombic shape; a stent according to the second variant can be made arbitrarily long.

The inventive stents may be coated, made of thin biaxially oriented film of polytetrafluoroethylene or copolymers of tetrafluoroethylene with HEXAFLUOROPROPYLENE or tetrafluoroethylene with performanceproblems ether content of the co monomer is not more than 2%. The film receive as described in the patent of Russian Federation №2117459, MKI6A 61 F 2/02 published 20.08.2002, Bulletin No. 23.

The shell may cover the outer or the inner and outer surface of the stent. The shell covering the inner surface of the stent may be made of 1-3 layers of polymeric material. The shell covering the outer surface of the stent may be made of 1-6 layers of polymeric material.

PTFE film has a structure characterized by two related penetrating matrices: the matrix polymer in the form of nodes connected by fibrils and matrix space voids, and these elements form a three-dimensional network. The shell can be made of a material having a volume fraction PR is e the distance between the voids in the amount of from 0.5 to 15 μm and an average chord volume from 0.1 to 10 μm, or from a material having a volume fraction of the space of voids from 25 to 94%, specific surface space voids from 0.1 to 9.0 μm2/μm3the average distance between voids in the amount of from 1.5 to 50 μm and an average chord volume from 0.4 to 30 μm. The best result shows the shell is made of a material having a volume fraction of the space of voids from 45 to 94%, specific surface space voids from 0.1 to 0.6 μm2/μm3the average distance between voids in the amount of from 5 to 45 μm and an average chord of volume from 5 to 30 μm.

The specified polymeric material in the form of a film thickness of from 0.005 mm to 0.25 mm is formed in a single case, covering the stent. When the stent has an inner and outer casings, they are sintered together in the spaces between the bends of the wire forming the wall.

The invention is illustrated in the drawings, is shown in Fig.1-16.

In Fig.1 shows a blank of the zigzag bent wire.

In Fig.2 presents a cross section of wire which is formed of the inventive stents.

In Fig.3 presents a cylindrical section of a stent made from the blank shown in Fig.1.

In Fig.4 shows a stent, Sassicaia with one ribbed surface, used as fastening multi-section stent shown in Fig.4.

In Fig.6 shows the blank from zigzag curved elements rhombic wire size and type (in the direction of zigzags along the axis of the stent).

In Fig.7 shows a fragment of the front element of the orthorhombic type.

In Fig.8 shows the profile of a fragment of the front element, shown in Fig.7.

In Fig.9 presents the workpiece zigzag curved elements rhombic type wire with the direction of the zigzag angle 90to the axis of the stent.

In Fig.10 presents the workpiece zigzag curved elements rhombic type wire with the direction of zigzags to the axis of the stent at an angle0<<90.

In Fig.11 shows a stent formed from the blank shown in Fig.6.

In Fig.12 presents the stent formed from the blank shown in Fig.9.

In Fig.13 presents the stent formed from the blank shown in Fig.10.

In Fig.14 shows a stent having an outer shell made of polytetrafluoroethylene.

In Fig.15 shows a stent having aruzona membranes of polytetrafluoroethylene, sintered around items stents, made of wire of circular cross section (a) and proposed section (b).

From zigzag curved wire (Fig.1) made of “Plastocrete-0,8” rectangular with rounded corners cross section (Fig.2) is formed by a cylindrical section (Fig.3). The zigzag wire is directed along the axis of the stent and have a deflection inside the stent, as shown in Fig.3. Deflection gives the front profile of the stent trapezoidal shape. The stent may include 1-10 sections. In the case where the stent includes two or more sections, they are fastened straight strips are made of an alloy of Plastocrete to 0.8”. In Fig.4 shows a stent, comprising 6 sections of the zigzag bent wire 1. Section two bonded fasteners, made in the form of straight stripes, ribbed on one side (Fig.5). The extreme section of the stent (Fig.4) have a variable radial stiffness with decreasing her to the ends of the stent (the first option is self-expanding endovascular stent).

According to the second variant of the inventive stent wire of alloy “Plastocrete-08”, rectangular with rounded corners-section (Fig.2), is bent in zigzags in the form of rhombic elements form ogotai wire. While the major diagonal of a rhombus can be directed along the longitudinal axis of the stent across the longitudinal axis of the stent or at an acute angle to the longitudinal axis of the stent (angle 0-90).

If a large diagonal of the rhombic element is directed along the axis of the stent (Fig.6) formed by the stent has the appearance shown in Fig.11. This stent has a maximum longitudinal stiffness and minimal torsional rigidity.

In the case when the major diagonal of the rhombic element is angled 90to the longitudinal axis of the stent, as shown in Fig.9, is formed stent shown in Fig.12. This stent has a maximum stiffness in compression and the minimum stiffness along the axis.

If a large diagonal of the rhombic element is directed at an acute angle to the longitudinal axis of the stent, as shown in Fig.10, the formed stent has the appearance shown in Fig.13. Such a stent has the most flexible design and can be easily bends in different planes.

In Fig.14 presents the stent 1, covered outside of the shell 2 formed from 1-6 layers dronorracoun film of polytetrafluoroethylene or a copolymer of tetrafluoroethylene with hakuchou, characterized by two related penetrating the matrix, the matrix polymer in the form of nodes connected by fibrils and matrix space voids, and these two matrices are connected in a three-dimensional network.

In Fig.15, the stent 1 is equipped with an outer shell 2 and the inner shell 3 made of 1-3 layers of biaxially-oriented film of the same polymer. In this case, the outer casing 2 fused with the inner shell 3 in the spaces between the bends of the wire.

In Fig.16 shows that when the rectangular cross section of the wire forming the inventive stent (Fig.16B), the area of contact of the inner and outer polymer shells more than would be the area of contact, if the stent was formed from wire of circular cross section (Fig.16A), the diameter of which is equal to the width of the wire, which is formed of the inventive stent. Increasing the area of contact of the membranes prevents unwanted separation during operation.

Rectangular profile wire which is used to make the inventive stent, in addition, allows to increase the inner diameter of the stent when the same external diameter, which helps to normalize blood flow. Variable stiffness along the length of the stent facilitates its adaptation to the article is rugosity alloy “Plastocrete-08 provides structural strength; its high korrozionostoykoy and biocompatibility.

Rentgencontrastnoe larger than that of nitinol allows the use of stents without additional radiopaque labels.

The inventive stent (both) passed clinical trials at the Center for cardiovascular surgery of the Central military clinical hospital. A. A. Vishnevsky when regimentofstorm prosthesis in the treatment of aneurysms of the abdominal aorta.

Declare endovascular stents were implanted in 6 patients at the age from 73 to 82 years archaeologically way through the femoral artery under local anesthesia. We used the wiring system (Introducer) diameter 24F. Four patients were infrarenal abdominal aortic aneurysm type II; one patient operated five years earlier on an aneurysm in the abdominal aorta of type II was observed false aneurysm of the proximal anastomosis linear aortic Explant; one patient was observed inconsistency of the proximal cone nitinol stent, established three years earlier.

When installing the inventive stents were observed intraoperative complications. In the postoperative period (observed is 1. Self-expanding endovascular stent made of metal zigzag bent wire forming a cylindrical surface, characterized in that it is made of wire, made of cobalt-iron-chromium-Nickel alloy “Plastocrete-08 and rectangular with rounded corners, the cross-section, and the stent has the form of at least one section, in which the zigzag wire is directed along the longitudinal axis of the stent and have a deflection inside the stent.

2. Self-expanding endovascular stent under item 1, characterized in that it includes 2-10 sections, in which the zigzag wire is directed along the longitudinal axis of the stent and have a deflection inside the stent.

3. Self-expanding endovascular stent under item 2, characterized in that the sections are fastened together by at least one fastening made from an alloy of Plastocrete-08” in the form of straight strips of rectangular cross-section, ribbed on the outside of the stent.

4. Self-expanding endovascular stent under item 1, characterized in that it is coated, made of polytetrafluoroethylene or copolymers of tetrafluoroethylene with HEXAFLUOROPROPYLENE or tetrafluoroethylene with performanceproblems ether content some matrix polymer in the form of nodes, United fibrils and matrix space voids, and these elements are connected in a three-dimensional network.

5. Self-expanding endovascular stent under item 4, characterized in that the shell is made covering the outer surface of the stent.

6. Self-expanding endovascular stent under item 4, characterized in that the shell is made covering the inner and outer surfaces of the stent.

7. Self-expanding endovascular stent under item 4, characterized in that the shell is made of a multilayer.

8. Self-expanding endovascular stent under item 6, characterized in that the sheath covering the inner and outer surface of the stent, sintered together in the spaces between the bends of the wire forming the stent.

9. Self-expanding endovascular stent made of metal zigzag bent wire forming a cylindrical surface, characterized in that it is made of wire, made of cobalt-iron-chromium-Nickel alloy “Plastocrete-08 and rectangular with rounded corners section, and zigzags made in the form of elements of the rhombic shape with rounded corners, and a large diagonal of a rhombus is directed at an angle of 0-90

11. Self-expanding endovascular stent under item 10, characterized in that the shell is made covering the outer surface of the stent.

12. Self-expanding endovascular stent under item 10, characterized in that the shell is made covering the inner and outer surfaces of the stent.

13. Self-expanding endovascular stent under item 10, characterized in that the shell is made of a multilayer.

14. Self-expanding endovascular stent under item 12, characterized in that the sheath covering the inner and outer surfaces of the stent, sintered together in the spaces between the bends of the wire forming the stent.

 

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