Delivery system and method for deployment of foreshortening endoluminal devices

#This invention relates generally to delivery systems for endoluminal devices, and, more specifically, to delivery systems for endoluminal devices that undergo a decrease in length when being expanded from a radially compressed configuration.

#Endoluminal devices comprise the general category of devices, such as stents, grafts, combinations thereof commonly referred to as stent-grafts or endoluminal prostheses, vena cava filters, and the like, that may be implanted in a body lumen. Endoluminal devices may be implanted by so-called “minimally invasive techniques” in which the prosthesis, restrained in a radially compressed configuration by a sheath or catheter, is delivered by a deployment system or “introducer” to the site where it is required. The introducer may enter the body through the patient's skin, or by a “cut down” technique in which the entry lumen, such as a blood vessel, is exposed by minor surgical means. When the introducer has been threaded into the body lumen to the prosthesis deployment location, the introducer is manipulated to cause the endoluminal device to be ejected from the surrounding sheath or catheter in which it is restrained (or alternatively the surrounding sheath or catheter is retracted from the endoluminal device), whereupon the endoluminal device expands to a predetermined diameter at the deployment location, and the introducer is withdrawn.

#As referred to herein, “distal” refers to the direction further away from the insertion point and “proximal” refers to the direction closer to the insertion point. Endoluminal devices, such as stents and vena cava filters, may expand by spring elasticity, balloon expansion, or by the self-expansion of a thermally or stress-induced return of a memory material to a pre-conditioned expanded configuration.

#The invention is best understood from the following detailed description when read in connection with the accompanying drawing. It is emphasized that, according to common practice, the various features of the drawing are not to scale. On the contrary, the dimensions of the various features are arbitrarily expanded or reduced for clarity. Included in the drawing are the following figures:

#FIG. 1A depicts a partial longitudinal section of an exemplary delivery system of the prior art for deploying a foreshortening-prone stent of the prior art;

#FIG. 1B depicts the delivery system of FIG. 1A in a partially deployed configuration;

#The invention will next be illustrated with reference to the figures wherein similar numbers indicate the same elements in all figures. Such figures are intended to be illustrative rather than limiting and are included herewith to facilitate the explanation of the apparatus of the present invention.

#Referring now to FIGS. 2A-2C, there is shown an exemplary delivery system 30 of this invention in various stages of deployment. Delivery system 30 comprises stent 10 in its compressed configuration, outer sheath 28 that radially surrounds the stent, pusher 27 positioned at the proximal end 11 of the stent, and a linkage 32 in communication with both the pusher and the outer sheath. Linkage 32 coordinates proximal retraction of outer sheath 28 with simultaneous distal advancement of pusher 27. Also shown in FIGS. 2A-2C is inner member 26, attached to an interface 42 at its proximal end and extending axially through stent 10 and pusher 27 to a connection with tip 24 at its distal end.

#As shown in FIGS. 2A-2C, linkage 32 comprises a rack and pinion system having intermeshing teeth 33. The rack and pinion system comprises a first rack 34 in linear communication with outer sheath 28, a second rack 36 in linear communication with the pusher 27, and a pair of rotationally-interlocked pinions 38 and 39 supported between the first rack and the second rack. Pinion 38 has a first diameter D1 and is adapted to interface with the rack 34. Pinion 39 has a second diameter D2 that is relatively smaller than first diameter D1, and is adapted to interface with the rack 36. It should be noted that the rack and pinion system shown in FIGS. 2A-2C is merely one exemplary embodiment, and other rack and pinion systems may also be devised to provide a similar effect. For example, the pinions may have a common diameter and may be mounted on separate shafts, with a gear mechanism, belt and sheave, or chain and sprocket mechanism provided between the pinions to provide the differential motion between the racks.