Flexible stent

Abstract

A preferred embodiment of a stent provides a folded strut section that provides both structural rigidity and reduction in foreshortening of the stent mechanism. A flexible section provides flexibility for delivery of the stent mechanism. In a second embodiment, flexible section columns are angled with respect to each other, and to the longitudinal axis of the stent. These relatively flexible sections are oppositely phased in order to negate any torsion along their length. In yet another embodiment, the flexible connector can take on an undulating shape (like an “N”), but such that the longitudinal axis of the connector is not parallel with the longitudinal axis of the stent. Finally, a new method is disclosed for making stents. The method consists of performing a standard photochemical machining process of cutting, cleaning and coating the tube with a photoresist. However, unlike former methods, the photoresist image is developed on the surface of the cylindrical metallic tube, which results in a controlled variable etching rate at selected sites on the cylindrical metallic tube during the etching process. Further embodiments provide living hinge connectors and connections along the length of the radial strut member.

Description

BACKGROUND ART [0001] A stent is commonly used as a tubular structure left inside the lumen of a duct to relieve an obstruction. Commonly, stents are inserted into the lumen in a non-expanded form and are then expanded autonomously (or with the aid of a second device) in situ. A typical method of expansion occurs through the use of a catheter mounted angioplasty balloon, which is inflated within the stenosed vessel or body passageway, in order to shear and disrupt the obstructions associated with the wall components of the vessel and to obtain an enlarged lumen. [0002] In the absence of a stent, restenosis may occur as a result of elastic recoil of the stenotic lesion. Although a number of stent designs have been reported, these designs have suffered from a number of limitations. These include restrictions on the dimension of the stent. [0003] Other stents are described as longitudinally flexible but consist of a plurality of cylindrical elements connected together. This design has ...

AI Technical Summary

Benefits of technology

[0013] It is an object of the invention to provide a stent having an enhanced degree of flexibility.

[0021] In addition, in the present embodiment described, adjacent radially rings start out of phase in the unexpanded state. Due to the diagonal oreintation of the connection points of the flexible connectors, upon expansion the radial rings tend to align themselves (“in” phase.) This results in more uniform cell space and thus improved scaffolding of the vessel. Further, there is described a “wavy” strut configuration, thereby facilitating both a reduced crimp profile for attaching the flexible connectors at or near a strut mid-point and reduced strain upon expansion, due to the strut itself contributing to a portion of the expansion.

Problems solved by technology

Although a number of stent designs have been reported, these designs have suffered from a number of limitations.

This design has at least one important disadvantage, for example, according to this design, protruding edges occur when the stent is flexed around a curve raising the possibility of inadvertent retention of the stent on plaque deposited on arterial walls.

This may cause the stent to form emboli or move out of position and further cause damage to the interior lining of healthy vessels.

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