Patent Application
20120172887
The present invention relates generally to medical devices and more specifically to delivery systems for expandable prostheses.
Use of expandable prostheses such as self-expanding stents is well known in the art. Most of the known delivery systems for such prostheses deploy the prosthesis in the distal to proximal direction, where “proximal” and “distal” are defined relative to the operator. However, it is advantageous to deploy a prosthesis in the proximal to distal direction when the placement of the proximal portion of the prosthesis is critical.
For example, use of self-expanding stents within the gastrointestinal (GI) tract is well-known. However, foreshortening stents tend to anchor within the GI tract at the initial location the stent makes contact with the body vessel, and then shorten along their primary axis toward that location. Thus, when using a foreshortening stent, the end that initially opens is relatively easy to place with accuracy, but the final location of the opposite end of the stent is variable.
There may be a clinical need to achieve precise anatomical placement of the proximal end of the self-expanding stent. For example, when there is a need to place a self-expanding stent very high in the esophagus, the proximal end of the stent should ideally be above the stricture but below the cricopharyngeal region of the throat to avoid aggravation of the nerves that control the coughing response and to avoid blocking the cricopharyngeal junction.
Thus, there is a need for a simple and reliable device to accurately position the proximal portion of an expandable prosthesis in the prosthesis's deployed configuration.
The use of splittable sheaths, such Cook Medical's as Peel-Away® sheath technology, to facilitate the insertion of catheters into body vessels is also known in the art. For example, U.S. Pat. No. 4,306,562 to Osborne describes a cannula that is configured to tear into two pieces as it is withdrawn from the body vessel in order to accommodate fittings, connectors, or other items larger than the cannula at the proximal end of the device.
The invention may include any of the following aspects in various combinations and may also include any other aspect described below in the written description or in the attached drawings.
A medical device includes an elongate catheter with a proximal end, a distal end, and a lumen. An expandable prosthesis is disposed about the distal end of the elongate catheter. A splittable sheath with a proximal end and a distal end is disposed about the expandable prosthesis. The splittable sheath has an opening disposed upon its proximal end. Also included is at least one actuating wire with a first portion, a second portion, and a first end. The first end of the actuating wire is disposed on the first portion of the actuating wire. The first portion of the actuating wire is everted about the distal end of the elongate catheter and disposed between the expandable prosthesis and the splittable sheath. The second portion of the actuating wire is disposed within the lumen of the elongate catheter. Additionally, a splitter with a blade element is attached to the first end of the actuating wire and partially disposed within the opening on the proximal end of the splittable sheath. When an operator at the proximal end of the elongate catheter pulls the actuating wire in the proximal direction the splitter moves in the distal direction and the blade element splits the splittable sheath.
The blade element may be hook-shaped or knife-shaped.
The blade element may also include a protective guard that covers the splitter.
The splittable sheath may include a longitudinal weakness that extends distally from the opening in the proximal end of the splittable sheath.
The proximal release delivery system may also include an outer catheter disposed about the splittable sheath. The outer catheter is configured to be displaced in the proximal direction before the splittable sheath is split.
The splittable sheath may be composed of polytetrafluoroethylene (PTFE) or polyethylene (PE).
The proximal release delivery system may also include an opening through the wall of the elongate catheter disposed on the distal end of the elongate catheter. The first portion of the actuating wire passes through the opening through the wall of the elongate catheter on the distal end of the elongate catheter. This allows the distal end of the splittable sheath to be attached to the distal end of the elongate catheter distal of the opening on the distal end of the elongate catheter without interfering with the placement of the actuating wire.
Another embodiment of the medical device includes an elongate catheter with a proximal end, a distal end, and a lumen. An expandable prosthesis is disposed about the distal end of the elongate catheter. A hinged splittable sheath with a longitudinal hinge attached to the expandable prosthesis is disposed about the expandable prosthesis. An opening is disposed on the proximal end of the hinged splittable sheath. Also included is an actuating wire with a first portion, a second portion, and a first end. The first end of the actuating wire is disposed on the first portion of the actuating wire. The first portion of the actuating wire is everted about the distal end of the elongate catheter and disposed between the expandable prosthesis and the hinged splittable sheath. The second portion of the actuating wire is disposed within the lumen of the elongate catheter. A splitter with a blade element is attached to the first end of the actuating wire and partially disposed within the opening on the proximal end of the hinged splittable sheath. When an operator at the proximal end of the elongate catheter pulls the actuating wire in the proximal direction, the splitter moves in the distal direction and the blade element splits the hinged splittable sheath.
The hinged splittable sheath may be composed of polytetrafluoroethylene (PTFE) or polyethylene (PE).
a) is a longitudinal view of the splitter wherein the splitter is hook-shaped.
b) is a longitudinal view of the splitter wherein the splitter is shaped like a knife.
c) is a longitudinal view of the splitter including a protective guard.
Referring now to the figures, a proximal release delivery system for expandable prostheses is shown. One embodiment of the delivery system is shown in
A splittable sheath 10 is disposed around expandable prosthesis 18 such that splittable sheath 10 retains expandable prosthesis 18 in a compressed configuration around elongate catheter 4. The splittable sheath 10 has a distal end 12 and a proximal end 14, where the proximal end 14 of splittable sheath 10 begins at the proximal end of expandable prosthesis 18. An opening 16 is located on the proximal end 14 of splittable sheath 10. Splittable sheath 10 may be manufactured of any of a number of well-known materials, including polytetrafluoroethylene (PTFE) and polyethylene (PE). Splittable sheath 10 may also be manufactured in such a way that it is predisposed to split longitudinally. For example, as shown in
An actuating wire 20 is partially disposed within the lumen 36 of elongate catheter 4. The actuating wire 20 has a first portion 22, a second portion 24, and a first end 26. The first end 26 is located on the end of the actuating wire 20 in the first portion 22. The first portion 22 of actuating wire 20 is everted about the distal end 6 of elongate catheter 4. The first portion 22 of actuating wire 20 then travels between expandable prosthesis 18 and splittable sheath 10 to the opening 16 located on the proximal end of splittable sheath 10. A splitter 28 having a blade element 42 is attached to the first end 26 of actuating wire 20 and is partially disposed within opening 16. The second portion 24 of actuating wire 20 travels within lumen 36 of elongate catheter 4 to the proximal end 8 of elongate catheter 4. The proximal release delivery system 2 may also include more than one actuating wire 20, splitter 28, and opening 16.
In order to deploy the expandable prosthesis 18, an operator located at the proximal end 8 of elongate catheter 4 advances proximal release delivery system 2 through a body vessel to the desired treatment location. Once the proximal end 38 of expandable prosthesis 18 is at the desired location, the operator pulls the second portion 24 of actuating wire 20 in the proximal direction causing the splitter 28 to move in the distal direction. As splitter 28 moves, blade element 42 splits the splittable sheath 10 longitudinally, releasing expandable prosthesis 18 and allowing it to deploy from the proximal end of the prosthesis. Thus, the proximal end 38 of expandable prosthesis 18 is accurately deployed at the desired location.
As shown in
As shown in
The blade element 42 of splitter 28 may be any shape effective for splitting splittable sheath 10. For example, as shown in
Another embodiment of proximal release delivery system 2 is shown in
As the operator pulls the second portion 24 of actuating wire 20 in the proximal direction, splitter 28 with blade element 42 moves in the distal direction and splits hinged splittable sheath 110 longitudinally. As hinged splittable sheath 110 begins to split, the expandable prosthesis 18 expands and deploys. As it deploys, expandable prosthesis 18 forces hinged splittable sheath 110 to its fully opened position. Additionally, expandable prosthesis 18 traps the split and fully opened hinged splittable sheath 110 between the expandable prosthesis 18 and a body vessel wall. Because hinged splittable sheath 110 is attached to expandable prosthesis 18, hinged splittable sheath remains at the deployment location with expandable prosthesis 18 after the operator removes the rest of proximal release delivery system 2.
Hinged splittable sheath 110 does not interfere with the proper placement and deployment of expandable prosthesis 18 because the surface area of hinged splittable sheath 110 is significantly smaller than outer surface area of expandable prosthesis 18 in its expanded configuration. As shown in
Hinged splittable sheath 110 may also extend along the full length of proximal release delivery system 2. The proximal release delivery system 2 of this embodiment may also include more than one splitter 28.
While preferred embodiments of the invention have been described, it should be understood that the invention is not so limited, and modifications may be made without departing from the invention. The scope of the invention is defined by the appended claims, and all devices that come within the meaning of the claims, either literally or by equivalence, are intended to be embraced therein. Furthermore, the advantages described above are not necessarily the only advantages of the invention, and it is not necessarily expected that all of the described advantages will be achieved with every embodiment of the invention.
