Short handle for a long stent

A stent delivery system for delivering a self-expanding stent includes a keel. The keel is used to pass a pushrod and a guidewire into a sheath through the tubular sidewall of the sheath, i.e., not through the lumen opening at the proximal end of the sheath. Accordingly, the entire length of travel of the proximal end of the sheath during deployment of the stent is not required to be inside of the handle, allowing the handle to be short. Since the handle is short, the handle is easy to manipulate.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an intra-vascular device and method. More particularly, the present invention relates to a device for deployment of a stent for treatment of luminal, i.e., intra-vascular, diseases.

2. Description of Related Art

In stent deployment systems, a self-expanding stent was restrained within a sheath. After positioning of the stent at the desired location via fluoroscopic guidance, the physician retracted the sheath to deploy the stent, i.e., to expose the stent and allow it to self-expand. To completely deploy the stent, the physician had to retract the sheath over the entire length of the stent, which was relatively cumbersome and typically required the use of both hands of the physician in the case of long self-expanding stents.

To illustrate,FIG. 1is a partially cutaway delivery system100for deploying a stent102in accordance with the prior art. Stent102is a radially self-expanding stent.

Delivery system100includes a pushrod104and a sheath106, sometimes called a catheter sheath. Pushrod104includes a distal end104D and a proximal end104P. Stent102is placed over distal end104D of pushrod104(while in other embodiments of the stent and pushrod, the stent could be located near the distal end of the pushrod which includes being over a portion of an end of the pushrod or being distal to a distal end of the pushrod). Distal end104D further includes radiopaque markers that allow the location of distal end104D and stent102to be precisely tracked. Proximal end104P of pushrod104terminates within and is mounted to a handle112or extends through handle112and out a port114of handle112.

Pushrod104is a hollow tube which acts as a guide wire lumen. A guide wire116can extend through pushrod104and distal end104D. The guide wire116can further extend through handle112and out port114.

Sheath106includes a distal end106D and a proximal end106P. Prior to deployment, stent102is radially compressed and restrained within distal end106D of sheath106. Proximal end106P of sheath106extends into handle112. Proximal end106P of sheath106is coupled to an actuation button118, sometimes called a thumb slider, of handle112. Sheath106is a hollow tube which acts as a pushrod lumen. Pushrod104extends through sheath106.

During use, stent102is placed over distal end104D of pushrod104and is radially compressed and restrained within distal end106D of sheath106. Stent102is introduced intra-vascularly and guided to the treatment site, e.g., an aneurysm.

Once stent102is properly positioned, sheath106is retracted by retraction of actuation button118thus deploying stent102. More particularly, stent102is self-expandable and as sheath106is retracted, stent102self-expands and is permanently deployed, e.g., anchored within a lumen of a patient. The guiding of a stent and deployment of a self-expanding stent are well known to those of skill in the art.

During deployment, sheath106must move the entire linear length X of stent102to completely uncover and thus deploy stent102. Since actuation button118is connected to and moves sheath106, actuation button118must also be moved the linear length X to retract sheath106over the entire linear length X of stent102as actuation button118and sheath106move in a strictly linear 1:1 motion.

In the case when stent102is a long self-expanding stent, length X is substantial, e.g., 200 mm or more. Accordingly, to accommodate the long travel of actuation button118, handle112must also be very long and at least linear length X. However, long handles are cumbersome and difficult to manipulate.

SUMMARY OF THE INVENTION

In accordance with one example, a stent delivery system for delivering a self-expanding stent includes a keel. The keel is used to pass a pushrod and a guidewire into a sheath through the tubular sidewall of the sheath, i.e., not through the lumen opening at the proximal end of the sheath. Accordingly, the entire length of travel of the proximal end of the sheath during deployment of the stent is not required to be inside of the handle, allowing the handle to be short. Since the handle is short, the handle is easy to manipulate.

Embodiments are best understood by reference to the following detailed description when read in conjunction with the accompanying drawings.

DETAILED DESCRIPTION

In accordance with one example, referring toFIGS. 2 and 3together, a stent delivery system200includes a keel216. Keel216is used to pass a pushrod204and a guidewire218into a sheath206through the tubular sidewall of sheath206, i.e., not through the lumen opening at proximal end206P of sheath206. Accordingly, the entire length of travel of proximal end206P of sheath206during deployment of a stent202is not required to be inside of handle212, allowing handle212to be short. Since handle212is short, handle212is easy to manipulate.

More particularly,FIG. 2is a partially cutaway delivery system200for deploying a self-expanding stent202in accordance with one embodiment of the present invention. Stent202is a radially self-expanding stent having a linear length X, e.g., 200 mm or more.

Delivery system200includes a pushrod204and a sheath206, sometimes called a catheter sheath. Pushrod204, sometimes called an inner member or inner shaft, includes a distal end204D and a proximal end204P. As is well known, the proximal end of a delivery system is referenced with respect to the operator's handle while the proximal end of a stent is referenced with respect to the end closest to the heart via the length of blood traveled from the heart.

Stent202is placed over distal end204D of pushrod204. In one embodiment, distal end204D further includes radiopaque markers that allow the location of distal end204D and stent202to be precisely tracked. Pushrod204includes a stop208or other structure to prevent stent202from being moved proximally during retraction of sheath206as discussed further below.

Proximal end204P of pushrod204terminates within and is mounted to a handle212. More particularly, handle212includes a housing214. Connected to, or integral with, housing214is a keel216. Proximal end204P of pushrod204is connected to keel216and thus to housing214. Accordingly, pushrod204does not move relative to housing214of handle212.

In this example, pushrod204is a hollow tube and includes a guide wire lumen. A guide wire218extends through pushrod204and extends out distal end204D of pushrod204. Guide wire218further extends out of proximal end204P of pushrod204, through keel216and out of a guide wire port220of keel216. As illustrated inFIG. 2, pushrod204extends through keel216such that proximal end204P of pushrod204is located at guide wire port220in this example.

Sheath206includes a distal end206D and a proximal end206P. Prior to deployment, stent202is radially compressed and restrained within distal end206D of sheath206. Sheath206extends through handle212and out a sheath port222of handle212. A sheath knob224is located on and attached to proximal end206P of sheath206.

In one example, sheath knob224and housing214includes thread226,228, respectively, allowing sheath knob224to be screwed on to and mounted to housing214. In accordance with this example, a sheath knob bearing230rotatably mounts sheath knob224to sheath206allowing sheath knob224to be unscrewed from housing214without rotation of sheath206.

Coupled to and extending distally from handle212is a strain relief232. Strain relief232distributes the bending force over a longer length of the sheath than just a point load at the end of the handle which may create kinking.

FIG. 3is an enlarged bottom perspective view of sheath206and keel216of delivery system200ofFIG. 2. Referring now toFIGS. 2 and 3together, sheath206is a hollow tube formed of a tubular sidewall and includes a pushrod lumen. Keel216extends radially inward from the side of housing214and penetrates radially into sheath206through the tubular sidewall of sheath206. Accordingly, keel216extends from outside of sheath206, through the tubular sidewall of sheath206, and into the pushrod lumen of sheath206.

As discussed further below, during deployment of stent202, sheath206is retracted. As sheath206is retracted, sheath206moves relative to keel216. Keel216, a rigid member, is thus forced against sheath206causing keel216to split sheath206.

As illustrated inFIG. 3, in one example, sheath206includes a breakaway302distal to keel216and a slit304proximal to keel316. In accordance with this example, breakaway302extends longitudinally along sheath206, i.e., parallel to longitudinal axis L of sheath206, distally from keel316. Generally, breakaway302is a region of sheath206having less structural integrity than the remainder of sheath206such that sheath206preferentially splits, sometimes called breaks, at breakaway302upon contact with keel216. Illustratively, breakaway302includes one or more perforations, scores, interlocking teeth, a zipper, a slit, or other feature that facilitates splitting of sheath206at breakaway302.

In one example, sheath206has elasticity sufficient to allow sheath206to be split and pulled around keel216without permanent deformation of sheath206. Accordingly, sheath206returns to the cylindrical shape of sheath206after being split by keel216. In accordance with this example, slit304, e.g., a longitudinal cut in sheath206, extends longitudinally proximally from keel216.

As set forth above, sheath206is a hollow tube and includes a pushrod lumen. Pushrod204extends through keel216and into sheath206.

During use, stent202is placed over distal end204D of pushrod204and is radially compressed and restrained within distal end206D of sheath206. Stent202is introduced intra-vascularly and guided to the treatment site, e.g., a stenosis or narrowing of the vascular vessel.

Once stent202is properly positioned, sheath206is retracted by retraction of sheath knob224. For example, sheath knob224is unscrewed from housing214. Sheath knob224is pulled from housing214, e.g., by the physician, thus retracting sheath206. Stent202is self-expandable and as sheath206is retracted, stent202self-expands as it is uncovered and is permanently deployed, e.g., anchored within a lumen of a patient.

During deployment, sheath206moves (is retracted) at least the entire length X of stent202to completely uncover and thus deploy stent202. Since retraction of sheath206is accomplished by pulling of sheath206out of handle212, handle212can be much shorter than stent202.

FIG. 4is a partially cutaway view of delivery system200taken from the bottom along line IV ofFIG. 2after deployment of stent202. As shown, sheath206moves (is retracted) at least the entire length X of stent202(seeFIG. 2) to completely uncover and thus deploy stent202. Illustratively, handle212has a linear length Y less than linear length X of stent202.

More particularly, keel216is used to pass pushrod204and guidewire218into sheath206through the tubular sidewall of sheath206, i.e., not through the pushrod lumen opening at proximal end206P of sheath206. Accordingly, the entire length of travel of proximal end206P is not required to be inside of handle212, allowing handle212to be short. Since handle212is short, handle212is easy to manipulate.

Referring now toFIG. 5, in accordance with this example, keel216A is directly attached to (or integral with) proximal end204P of pushrod204A, for example, with adhesive, welding, threads, or mechanical fasteners. Stated another way, keel216A is an extension of pushrod204A that passes from within sheath206A, through the cylindrical, sometimes called tubular, sidewall of sheath206A, and to housing214A of handle212A. In one example, as indicated by the dashed line, keel216A protrudes outside from housing214A.

Guide wire218A passes through guide wire port220A and into keel216A, passes through keel216A and into sheath206A, and from keel216A passes into pushrod204A. Use of keel216A allows handle212A to be short and easy to manipulate.

FIG. 6is a partially cutaway delivery system600for deploying a self-expanding stent in accordance with yet another embodiment of the present invention. Pushrod204B, sheath206B, handle212B, housing214B, guide wire218B, guide wire port220B, sheath port222B, strain relief232B, breakaway302B, and slit304B of delivery system600ofFIG. 6are similar to pushrod204, sheath206, handle212, housing214, guide wire218, guide wire port220, sheath port222, strain relief232, breakaway302, and slit304of delivery system200ofFIGS. 2 and 3, respectively, and so are not discussed further.

Referring now toFIG. 6, in accordance with this example, keel216B extends distally from the rear of housing214B and penetrates into sheath206B. In accordance with this configuration, pushrod204B extends straight through handle212B and without any significant bending. Recall in delivery system200ofFIG. 2, sheath206extends straight through handle212and pushrod204bends radially outward to extend through both keel216and the tubular sidewall of sheath206to the side of housing214.

However, referring still toFIG. 6, sheath206B is bent radially outwardly to extend out the side of housing214B through sheath port222B. Further, in accordance with this example, sheath206B is retracted by use of a ratchet mechanism702.

Specifically, the physician retracts, i.e., moves proximally, thumb slider704to retract sheath206B. Once thumb slider704is fully retracted, i.e., moved proximally to the end of travel of thumb slider704such that thumb slider704is in abutting contact with housing214B, thumb slider704is advanced, i.e., moved distally. However, sheath206B is engaged with housing214B such that thumb slider704is advanced without advancement of sheath206B. This procedure is continuously repeated to retract sheath206B to deploy the stent. As sheath206B is retracted, sheath206B feeds out of sheath port222B.

To illustrate, a first tooth706A of teeth706of sheath206B includes an engagement surface712and a sliding surface714. Engagement surface712is distal to sliding surface714. Further, engagement surface712is radially perpendicular to longitudinal axis L of sheath206B. Conversely, sliding surface714extends from engagement surface712proximally inward and at an angle to engagement surface712.

To further illustrate, a first tooth708A of teeth708of thumb slider704includes an engagement surface716and a sliding surface718. Engagement surface716is proximal to sliding surface718. Further, engagement surface716is radially perpendicular to longitudinal axis L of sheath206B. Conversely, sliding surface718extends from engagement surface712distally outward and at an angle to engagement surface716.

To further illustrate, a first tooth710A of teeth710of housing214B includes an engagement surface720and a sliding surface722. Engagement surface720is proximal to sliding surface722. Further, engagement surface720is radially perpendicular to longitudinal axis L of sheath206B. Conversely, sliding surface722extends from engagement surface720distally outward and at an angle to engagement surface720.

FIG. 8is a partially cutaway delivery system800for deploying a self-expanding stent in accordance with another embodiment of the present invention. Pushrod204C, sheath206C, handle212C, housing214C, guide wire218C, guide wire port220C, strain relief232C, breakaway302C, and slit304C of delivery system800ofFIG. 8are similar to pushrod204B, sheath206B (absent teeth706), handle212B, housing214B, guide wire218B, guide wire port220B, strain relief232B, breakaway302B, and slit304B of delivery system600ofFIG. 6, respectively, and so are not discussed further.

Referring now toFIG. 8, in accordance with this example, handle212C includes a spool802coupled to housing214C. More particularly, spool802rotates on an axle804extending through spool802and coupled to housing214C.

Proximal end206P of sheath206C is connected to spool802. Spool802, sometimes called a coil, provides a means for retracting sheath206C. In this example, spool802includes a spool knob806that is rotated by the physician thus rotating spool802around axle804. As spool802rotates, sheath206C is wound into spool802and thus retracted.

By winding (coiling) sheath206C around spool802, handle212C can be much shorter than the length of the stent. Since handle212C is short, handle212C is easy to manipulate.