Hoop stent

Details Hoop stent Hoop stent

1998-11-03

2001-07-10

Truong, Kevin (Department: 3731)

Surgery

Instruments

Internal pressure applicator

C606S194000

Reexamination Certificate

active

06258114

ABSTRACT:

FIELD OF THE INVENTION
This invention relates to stents for use in vascular surgery.
BACKGROUND OF THE INVENTION
A wide variety of stent designs have been proposed for use in the vascular system. Typically, the stents are used to hold open a length of blood vessel which has been closed or occluded by some growth within the blood vessel. Balloon expandable stents and self-expanding stents are commercially available and have been used successfully for treatment of a number vascular diseases. Das, Stent, U.S. Pat. No. 5,554,181 (Sep. 10, 1996) shows a wire stent having a number of hoops all attached to a radially disposed spine, all of which may be formed of a single wire. Likewise, Hillstead, Endovascular Stent Apparatus and Method, U.S. Pat. No. 4,856,516 (Aug. 15, 1989). The stents are folded upon a catheter pusher and retained within a catheter sheath before release into the body. These stents must be radially compressed to fit within the catheter sheath, and expand elastically or may be expanded in elastically by a balloon. They are not susceptible to being stretched or elongated in the along their long axes to reduce their overall diameter.
SUMMARY
The stent and stent delivery system described herein are designed for insertion into blood vessels and other lumens of the body. The self-expandable stent is composed of a single small diameter (0.005 inch) nitinol wire which is doubled first by making a bend at its mid-portion. The wire pair is then led around a tubular jig to form a hoop, and the wires are joined by double twisting or point welding to form a strut, then led around the tubular jig to form another hoop, joined to form another strut, and so on until the desired number of hoops are formed. The stent may be stretched along the long axis of the stent, whereupon the hoops are deformed into ellipses disposed at an angle approximately midway between the long axis of the stent and the radius of the stent, and the overall diameter of the stent is reduced by this deformation.
To deploy the stent, it is stretched out completely on the surface of a small catheter (3-F). The catheter contains a specially designed angled tip guide wire provided with a low-profile hook. The front end of the constrained stent is hung on the hook. The hook comes out from the catheter's lumen through a hole and goes back into the catheter through another hole. A monofilament retrieving loop runs from the proximal end of the deployment catheter to the to the proximal end of the stent. The proximal end of the retrieving loop is fastened to a sliding ring attached to the proximal end of the 3-F catheter shaft. Before final release of the stent, the retrieving loop may be operated via the sliding ring to pull the stent in order to correct for any error in the initial placement of the stent. After the stent is properly placed and the retrieving loop may be severed to release the stent from the delivery catheter. The stent has thermal shape memory or pseudoelasticity which facilitates deployment.


REFERENCES:
patent: 4512338 (1985-04-01), Balko
patent: 4800882 (1989-01-01), Gianturco
patent: 4856516 (1989-08-01), Hillstead
patent: 4913141 (1990-04-01), Hillstead
patent: 5135536 (1992-08-01), Hillstead
patent: 5554181 (1996-09-01), Das
patent: 5575816 (1996-11-01), Rudnik
patent: 5578149 (1996-11-01), De Scheerder
patent: 5766238 (1998-06-01), Lau et al.
Cragg, et al., Nonsurgical Placement of Arterial Endoprosthesis: A new Technique Using Nitinol Wire, 147 radiology 261 (Apr. 1983).
Dotter, Transluminal Expandable Nitinal Coil Stent Grafting, 147 radiology 259 (Apr. 1983).

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