Covered stent and preparation method therefor
A covered stent comprises a radially compressible inner stent and an outer stent covering the inner stent, the inner stent comprises an inner support skeleton and an inner coating film arranged on the inner support skeleton; and the outer stent covering the inner stent, wherein the outer stent covers at least part of the inner stent, the outer stent comprises an outer support skeleton and an outer coating film arranged on the outer support skeleton, one end of the outer coating film is hermetically connected to the inner coating film, and the resilience of the outer coating film is greater than that of the inner coating film. The inner covering film is relatively soft. The outer covering film can rebound quickly, the outer stent effectively fills the gap between the inner stent and the wall of the lumen, so as to prevent inner leakage.
1. A covered stent, wherein the covered stent comprises a radially compressible inner stent and an outer stent covering the inner stent, the inner stent comprises an inner support skeleton and an inner coating film arranged on the inner support skeleton; and
the outer stent covering the inner stent, wherein the outer stent covers at least part of the inner stent, the outer stent comprises an outer support skeleton and an outer coating film arranged on the outer support skeleton, one end of the outer coating film is hermetically connected to the inner coating film; wherein the outer coating film and the inner outer coating film are spaced apart from each other, the outer stent comprises a tapered section and a straight section connected to the tapered section, and one end of the tapered section away from the straight section is hermetically connected to the inner stent, and wherein the hardness of the outer coating film is higher than the inner outer coating film;
wherein the thickness of the outer coating film is smaller than that of the inner coating film; and
wherein the thickness of the outer coating film is 10 μm to 50 μm, and the thickness of the inner coating film is 20 μm to 70 μm.
2. The covered stent of claim 1 , wherein both the inner coating film and the outer coating film are PTFE films, and the peel force of the outer coating film is not smaller than that of the inner coating film.
3. The covered stent of claim 1 , wherein the radial support force of the outer support skeleton is smaller that of the inner support skeleton.
4. The covered stent of claim 1 , wherein the diameter of the straight section is not less than 1.5 times the diameter of the inner stent.
5. The covered stent of claim 1 , wherein both the inner coating film and the outer coating film are PTFE films, and the peel force of the outer coating film is not smaller than that of the inner coating film.
6. The covered stent of claim 1 , wherein the light transmittance of the outer coating film is greater than that of the inner coating film, and wherein light transmittance is defined as the ratio of the luminous flux transmitted through an object to the luminous flux irradiated to the object.
7. The covered stent of claim 6 , wherein light transmittance is T=I t /I 0 , where I t is the intensity of transmitted light and I a is the intensity of light absorbed.
8. The covered stent of claim 1 , wherein one end of the outer coating film is connected to the inner coating film, another end of the outer coating film is spaced apart from the inner coating film, a cavity with an opening is defined between the inner coating film and the outer coating film, and the opening faces towards to the proximal end.