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CN-116157165-B - Intravascular indwelling stent

CN116157165BCN 116157165 BCN116157165 BCN 116157165BCN-116157165-B

Abstract

The invention provides a stent for intravascular placement, which can achieve both the blood flow preservation property of a branch vessel and the embolization property of a tumor part. The stent for intravascular indwelling comprises a tubular strut (11) having an expandable diameter, and a polymer film (21) covering the whole of the strut (11), wherein a plurality of through holes (22) are formed in the polymer film (21), the through holes communicate the inside of the tube with the outside of the tube of the stent for intravascular indwelling, the opening size is between 0.02mm and 0.2mm, the opening occupancy is between 25% and 41%, and the dividing surface density is between 9.5/mm and 30/mm.

Inventors

  • NAKAYAMAYASUHIDE
  • YOSHIFUMI SUGIURA
  • TANAKA TAKAHARU

Assignees

  • 生物管株式会社

Dates

Publication Date
20260512
Application Date
20210715
Priority Date
20200717

Claims (9)

  1. 1. An intravascular stent to be placed in a blood vessel, comprising: A stent body having a tubular shape capable of expanding a diameter, and A polymer film coating the stent body, A plurality of through holes which communicate the inside of the tube with the outside of the tube of the intravascular stent are formed in the polymer film, and the opening size at the time of diameter expansion is 0.02mm to 0.2 mm; the ratio of the opening area of all the through holes included in the unit area with respect to the unit area of the outer surface of the polymer film is an opening occupancy, The ratio of the lengths of the opening edges of all the through holes included in the unit area with respect to the unit area of the outer surface of the polymer film is a divided area density, The occupancy of the opening at the time of expanding is 25-41%, The dividing surface density at the time of expanding is 9.5/mm or more and 30/mm or less.
  2. 2. The stent for endovascular indwelling according to claim 1, wherein, The plurality of through holes include through holes having different opening sizes when the diameter is expanded.
  3. 3. The stent for endovascular indwelling according to claim 1 or 2, wherein, The thickness of the polymer film is 1-100 μm.
  4. 4. The stent for endovascular indwelling according to claim 1 or 2, wherein, The stent body is configured such that ring-shaped wires are arranged along the extending direction of the stent for intravascular indwelling, the ring-shaped wires are repeatedly buckled in a corrugated manner along the circumferential direction of the stent for intravascular indwelling, The through holes are arranged so as to fill gaps between the annular wires adjacent to each other.
  5. 5. The stent for endovascular indwelling according to claim 3, wherein, The stent body is configured such that ring-shaped wires are arranged along the extending direction of the stent for intravascular indwelling, the ring-shaped wires are repeatedly buckled in a corrugated manner along the circumferential direction of the stent for intravascular indwelling, The through holes are arranged so as to fill gaps between the annular wires adjacent to each other.
  6. 6. The stent for endovascular indwelling according to claim 1 or 2, wherein, The opening size of the through hole is more than 0.06mm and less than 0.12mm when the diameter of the through hole is expanded, The occupancy of the opening at the time of expanding is 30-35%, The dividing surface density at the time of expanding is 14/mm or more and 20/mm or less.
  7. 7. The stent for endovascular indwelling according to claim 3, wherein, The opening size of the through hole is more than 0.06mm and less than 0.12mm when the diameter of the through hole is expanded, The occupancy of the opening at the time of expanding is 30-35%, The dividing surface density at the time of expanding is 14/mm or more and 20/mm or less.
  8. 8. The stent for endovascular indwelling according to claim 4, wherein, The opening size of the through hole is between 0.06mm and 0.12mm when the diameter of the through hole is enlarged, the occupancy of the opening when the diameter is enlarged is between 30% and 35%, The dividing surface density at the time of expanding is 14/mm or more and 20/mm or less.
  9. 9. The stent for endovascular indwelling according to claim 5, wherein, The opening size of the through hole is between 0.06mm and 0.12mm when the diameter of the through hole is enlarged, the occupancy of the opening when the diameter is enlarged is between 30% and 35%, The dividing surface density at the time of expanding is 14/mm or more and 20/mm or less.

Description

Intravascular indwelling stent Technical Field The present invention relates to an intravascular stent to be placed in a blood vessel. Background Among surgical treatment methods for aneurysms caused by local brittle weakness of the vessel wall, a method using an intravascular indwelling stent has been studied. In a vascular operation for embolizing a part of an aneurysm by indwelling an endovascular stent at a site where the aneurysm has occurred, blood is thrombosed in the aneurysm by using the case where the endovascular stent embolizes blood into the aneurysm. Treatment using an intravascular stent does not involve a large incision due to an open abdomen or craniotomy, as in the case of treatment in which a blood vessel having an aneurysm is replaced with an artificial blood vessel, or treatment in which the neck of the aneurysm is clamped with a clip. The vascular endothelial cells, which release the vasoactive substance and regulate vascular tension and blood coagulation, constitute vascular endothelium in the blood vessel where the endovascular indwelling stent is indwelled. Thrombomodulin, heparin-like substances, prostacyclin, nitric oxide, tissue plasminogen activator (plasminogen activator) and other various antithrombotic substances are produced in vascular endothelium. An intravascular indwelling stent in which the entire surface of the strut is covered with a polymer film also suppresses thrombosis caused by a strut made of metal by making the inner peripheral surface of the intravascular indwelling stent smooth. The stent for intravascular indwelling covered with the polymer film can also suppress intimal thickening due to platelets in thrombus. The fine through-holes formed in the polymer film promote the invasion of vascular endothelial cells into the inner side of the stent for intravascular indwelling. The promotion of invasion of vascular endothelial cells accelerates intimation of the stent for intravascular indwelling and further suppresses thickening of neointima. As an example of the through holes formed in the polymer film, for example, the through holes have a diameter of 100 μm and are arranged in a straight line at intervals of 200 μm. The rows of through holes arranged in a straight line are equally arranged in the circumferential direction of a stent having a diameter of 8mm so that the center angle is 15 ° (see, for example, patent documents 1 and 2). As in the case of an aneurysm generated at the branching portion between an internal carotid artery and a posterior artery, cases in which a branch blood vessel is branched from the body portion of the aneurysm are not rare. The stent for intravascular indwelling having a through-hole formed in a polymer film can inhibit thickening of a neointima and embolize a tumor orifice in an aneurysm, and can also be embolized even at a branching orifice of a branched blood vessel. Patent document 3 discloses an intravascular stent in which the occupancy of the openings of fine through holes is 20% to 50% in order to embolize the ostium of an aneurysm and to ensure blood flow in a branch vessel (see patent document 3, for example). Prior art literature Patent literature Patent document 1 Japanese patent application laid-open No. 2004-261567 Patent document 2 Japanese patent application laid-open No. 2004-313322 Patent document 3 Japanese patent application laid-open No. 2012-55649 Disclosure of Invention Problems to be solved by the invention On the other hand, the range of the opening occupancy disclosed in patent document 3 is determined based on fluid analysis using a blood vessel model. For example, when the occupancy of the openings of the fine through holes is large, blood flowing into the aneurysm from the downstream side of the orifice portion flows out from the upstream side of the orifice portion by rotating once in the upstream direction along the inner wall of the aneurysm. Conversely, when the opening occupancy of the through hole is small, blood flowing into the aneurysm from upstream of the orifice flows out from downstream of the orifice after one rotation along the inner wall of the aneurysm in the downstream direction. Based on the analysis results of the reversal of the blood flow pattern in these aneurysms, the occupancy of the openings of 25% to 50% was determined as a range in which the blood flow in the aneurysms substantially stopped. On the other hand, the stent for arterial treatment which is placed in a blood vessel is recognized as a foreign substance by a living tissue material such as vascular endothelial cells. In an intravascular indwelling stent identified as a foreign substance, the stent is intimated by covering with connective tissue generated by vascular endothelial cells or the like so that the stent is not identified as a foreign substance in a blood vessel. The intimation was not considered in the analysis of the working fluid using the vascular model, (i) the intimation factor at the tumor orifice an