FIELD

Embodiments relate to the field of cardiovascular medical instruments, in particular to a covered stent.

BACKGROUND

In the prior art, in order to solve the problem of involvement of bifurcated vessels in a lesion site, a covered stent fenestrated technology is generally used, which can isolate the lesion vessels but also keep the bifurcated vessels clear. However, the technology still has the problems of difficult bifurcated port positioning, poor connection matching between branches and a main body, poor angle adaptability after placement of connection stent and the like, and how to effectively connect the branches and the main body to achieve an ideal effect of isolation and shunt is a research direction of this technology.

In-situ fenestrated technology of a covered stent is a technology that first inserts a complete coating main body, then introduces a physical puncture or laser breakdown to punch holes at branch positions, and finally introduces a connection stent. The technology is feasible in theory, but there are some problems in practice, such as debris falling off in the holes punching process, uncontrollability of the hole size, and possible thrombosis and the like during the fenestrated process.

In view of the above problems, the Chinese patent with the publication number of CN203841852U proposes a fenestrated side branch covered stent, namely, a short branch of a transition segment is placed in a position to be opened in the main stent in advance, and a polymer flexible segment is used to connect the opening position at the adjacent opened position, so as to connect with the short branch. The method can be positioned through the short branch of transition segment, and can be well connected through the polymer flexible segment. Compared with a covered stent with only a short branch of rigid built-in transition segment, the covered stent can adjust the connection angle with the short branch within a certain range, such that the risk of endoleak caused by loose connection position can be effectively avoided. However, due to the fact that the polymer flexible segment lacks metal stent support and is placed in the covered stent, it may cause the risk of branch blood supply shortage due to branch closure under the impact of blood flow, which increases the burden of patients' self-healing. In addition, the polymer flexible segment in the patent is completely fixed to the main body stent, and when a branch stent is externally connected, an adjusted angle of the branch stent can be limited to a certain extent.

The Chinese patent application with the publication number of CN 102488575A provides an aorta fenestration stent, which opens a side window at a coating portion of a main stent without a metal framework and introduces a small stent with a metal framework support into the inner wall of the side window, and the axis of the small stent is parallel to the axis of the main stent, and the small stent serves to connect the main stent and a branch stent. The metal framework of the small stent3improves the radial support force of the small stent and can effectively fix branch channels, but reduces the flexibility of the small stent. When the branch stent is introduced and connected with the small stent, the branch stent is easily restrained at the joint of being connected with the small stent, especially for complex branch vessels having a large degree of bending. Moreover, the compatibility between the branch stent and the small stent is poor, which may lead to a risk of typeIendoleak. In addition, there is also the problem that the local stress in the connection section is too high and the branch vessels are pressed.

SUMMARY

Embodiments described herein provide a covered stent which can effectively fix the external branch stent and has good flexibility addressing the defects of the prior art.

A technical solution adopted to solve technical problems thereof is to configure a covered stent which includes a tubular main stent and a connection stent disposed on the main stent.

An opening is formed in a side wall of the main stent. The connection stent includes a fixed segment connected to the side wall of the main stent and a free segment connected to the fixed segment. Each of the fixed segment and the free segment includes a stent and a coating covering the surface of the sent. One end of the free segment distant from the fixed segment is connected to the edge of the opening, and a gap is formed between one side of the free segment near to the side wall of the main stent and the side wall of the main stent.

The covered stent of the application introduces the connection stent inside the main stent, and the fixed segment and the free segment of the connection stent are provided with the stent, so as to ensure the support force of the connection stent in the radial and axial directions, and avoid the risk of channel closure due to the impact pressure of blood flow. Further, the two ends of the free segment are connected to the fixed segment and the edge of the opening of the main stent, while the middle portion of the free segment is not fixed to the side wall of the main stent. Compared with a general fenestrated stent, the covered stent can effectively solve the problem of the limitation of an adjusted angle of an external connection stent at the connection segment. Therefore, the covered stent of the application can be suitable for various complicated and changeable branch vessel configurations, and has the advantages of good universality, simple structure and the like.

In addition, a corresponding number of the connection stents can be introduced according to the number of branch vessels at a specific lesion site, and if there is no lesion in the branch vessels, the connection stent serves only as a drainage to prevent series of complications caused by the closure of the branch vessels; if branches involve a lesion, an external branch stent can be introduced at the branch fracture, which can be used in conjunction with the connection stent to play an isolation effect and achieve the purpose of treatment.

