Removable stent-graft

Abstract

A removable device such as a stent-graft, intended for applications where it may be desirable to remove the device at some time following implantation. The stent-graft of the present invention includes a helically-wound stent component provided with a covering of graft material. It is removable by gripping an end of the helically-wound stent component with a retrieval device and applying tension to the stent component in the direction in which it is intended to be withdrawn from the site of implantation. The use of such a retrieval device allows the stent-graft to be removed remotely, such as via a catheter inserted into the body at a different location from the implantation site. The design of the stent-graft is such that the stent component is extended axially while the adjacent portion of the graft separates between windings of the stent component. The axial extension of the stent component, with portions of the graft still joined to the stent component, allows the device to be “unraveled” (or “unwound”) and removed through a catheter of diameter adequately small to be inserted into the body cavity that contained the stent-graft. It is removed atraumatically, without incurring significant trauma to the body conduit in which it had been deployed.

Description

FIELD OF THE INVENTION [0001] The present invention relates to the field of removable stent-grafts. BACKGROUND OF THE INVENTION [0002] Endoluminal stenting has provided a major advancement in clinical treatment modalities offering a significant reduction in perioperative treatment times, iatrogenic injury, postoperative morbidity and healing times. Even with the unprecedented clinical advantages of these devices, there still remains a number of limitations and disadvantages of the technologies currently available. The two primary technologies available for endoluminal stenting are the use of bare metal stents and stent devices provided with a covering or lining of a tubular graft material, i.e., stent-grafts. Either of these technologies may be made to be deployed via inflation of a catheter balloon (e.g., stainless steel stents) or to be self-expanding (e.g., nitinol stents). All of these technologies exhibit a common disadvantage in that none of the commercially available devices ...

AI Technical Summary

Benefits of technology

[0019] The device of the present invention is removable by gripping an end of the helically-wound structural support with a retrieval device and applying tension to the structural support in the direction in which it is intended to be withdrawn from the site of implantation. The design of the device is such that the structural support (e.g., stent component) is extended axially while the adjacent portion of the graft separates between windings of the structural support. For a stent-graft, for example, the axial extension of the stent component, with adjacent portions of the graft still joined to the stent component, allows the device to be “unraveled” (or “unwound”) and removed through a catheter of diameter adequately small to be inserted into the body cavity that contained the previously-deployed stent-graft.

[0020] The stent-graft is cohesively removable (i.e., is cohesively disassembled), meaning that it is removed in its entirety, without loss of pieces or the formation of separate remnants during the removal (e.g., the unraveling) process.

Problems solved by technology

All of these technologies exhibit a common disadvantage in that none of the commercially available devices are designed to be removable after implantation.

Even though great strides have been undertaken to enhance biocompatibility of these devices, it is still a synthetic, non-living tissue device that constitutes a foreign body.

As a result, living tissue has a number of limitations and / or reactions in coping with such a foreign body.

Typically, when a synthetic device becomes infected, or colonized by bacteria, there is little success in resolving such an infected device or infected area short of device removal from the patient.

In some instances, if an infected synthetic device cannot be removed enabling the antibiotic treatment of the effected living tissue, patient mortality can result due to septic shock.

Another issue associated with implantation of endoluminal stents and stent-grafts is foreign body reaction.

Even though these devices aid in limiting the amount of restenosis as a result of vessel or ductal injury, after a period of time the vessel or duct may generate a hyperplastic tissue (restenotic) or calcific stone formation response due to the presence of the foreign body.

Two of the key challenges in local drug delivery are the delivery mechanism and the drug elution profile or therapeutic window of the drug delivery.

The described stent is removed intact, at its fully deployed dimensions, and may consequently pose a risk of trauma during removal.

This in-growth may result in trauma to the implant site during retrieval.

However, this graft covering is discontinuous and therefore cannot offer the advantages of a continuous graft covering extending for all or a major portion of the length of the implantable stent structure.

Images