# Patent

## Title
Deployment system for an endoluminal device

## Abstract

The present invention is directed to a deployment system for an endoluminal device. The deployment system includes a confining sheath placed around a compacted endoluminal device. A deployment line is provided in the system that is an integral extension of the sheath. As the deployment line is actuated, the sheath retracts from around the compacted endoluminal device. As the sheath retracts from around the endoluminal device, material from the sheath may be converted into deployment line. Once the sheath is retracted from around the compacted endoluminal device, the endoluminal device expands in configuration and repairs vascular or cardiac structures of an implant recipient. Any remaining sheath material is removed from the implantation site along with the deployment line.

## Background
FIELD OF THE INVENTION
The present invention relates generally to implantable medical device assemblies. In particular, the invention relates to means for deploying an endoluminal device within vascular or cardiac structures of an implant recipient.
BACKGROUND OF THE INVENTION
Various implantable medical devices for repairing or reinforcing cardiac and vascular structures have been developed in recent years. Some of these devices can be implanted inside a particular vascular or cardiac structure through so-called interventional, or endovascular, techniques. Interventional techniques involve surgically accessing the vascular system through a conveniently located artery or vein and introducing distal portions of a medical device assembly into the vascular system through the arterial or venous access point. Once the medical device assembly is introduced into the vascular system, it is threaded through the vasculature to an implantation site while proximal portions of the assembly having manually operated control means remain outside the body of the implant recipient. The medical device component of the assembly is then deposited at the implantation site and the remainder of the distal portion of the medical device assembly removed from the vascular system through the access point.
Exemplary interventional medical device assemblies include a catheter. The catheter can be used to precisely position the medical device at an implantation site as well as participate in deployment of the medical device at the implantation site. Some catheters have guidewires running their length to aid in positioning and deployment of the medical device. As an alternative to the guidewire, a catheter may be coaxial with an inner sleeve running inside the length of the catheter. The inner sleeve is used to hold an implantable medical device in position while the outer catheter is pulled, causing deployment of the device. Handles, knobs, or other manually operated control means are attached to the opposite end of the catheter in this assembly.
Some implantable medical devices, such as stents, stent-grafts, or other endoluminal devices often require reconfiguration from an initial compacted form to an expanded cylindrical configuration as the device is deployed at an implantation site. These devices can expand on their own by virtue of the design and composition of their structural elements or through the use of an inflatable balloon placed inside the devices.
Self-expanding endoluminal medical devices are maintained in a compacted configuration in a variety of ways. Some devices are maintained in a compacted configuration by simply confining the compacted devices inside a catheter, or similar tool. Other devices are placed inside a sheath following compaction. In these assemblies, a control line is often used to assist in releasing the endoluminal device from the sheath.
In U.S. Pat. No. 6,352,561, issued to Leopold et al., a sheath is formed around an expandable endoluminal device and a control line used to maintain the sheath around the endoluminal device. The sheath is formed by folding a length of polymeric material in half and stitching the opposing edges together with the control line. The stitching pattern permits the control line to be removed from the sheath by pulling on a proximal end of the control line. As the control line becomes unstitched from the sheath, the endoluminal device is progressively released from confinement within the sheath. The control line is removed from the assembly as a distinct entity while the sheath remains at the implantation site.
In U.S. Pat. No. 5,647,857, issued to Anderson et al., an endoluminal device is held in a collapsed configuration over a catheter by a sheath. The assembly is provided with a control line having a free end and an end attached to a collar component of the catheter. The sheath is removed from the endoluminal device by pulling on the control line. As the control line is pulled, it cuts through and splits the sheath material from distal end to proximal end. As the sheath splits open, the endoluminal device is freed to expand. Unlike Leopold et al., the control line remains mechanically attached to the sheath and catheter assembly following deployment of the endoluminal device.
In U.S. Pat. No. 6,447,540, issued to Fontaine et al., a confining sheath is removed from around an endoluminal device with a control line that cuts through and splits the sheath material when pulled by a practitioner, much like Anderson et al. As with Leopold et al, the control line can be completely removed from the assembly as a distinct entity.
In U.S. Pat. No. 5,534,007, issued to St. Germain et al., a single-walled sheath that can collapse and shorten along its length is placed around a stent. As the distal portion of the sheath is retracted, it uncovers the stent. The uncovered stent is free to expand. A control line can be used to exert a pulling force on the collapsible sheath as a means of removing the sheath from the stent. The control line remains attached to the sheath during and subsequent to deployment of the stent.
In U.S. Pat. No. 6,059,813, issued to Vrba et al, a double-walled confinement sheath for an endoluminal device is described. In an assembly made of these components, the endoluminal device is placed over a catheter shaft in a collapsed configuration. An outer tube is placed in slidable relationship over the catheter. The distal end of the outer tube does not extend to cover the endoluminal device. Rather, the double walled sheath is placed over the collapsed endoluminal device. The inner wall of the sheath is attached to the catheter shaft near the proximal end of the endoluminal device. The outer wall of the double-walled sheath is mechanically attached to the outer tube. Movement of the outer tube relative to the catheter causes the outer wall of the sheath to move past the inner wall of the sheath. Movement of the outer tube in the proximal direction causes the sheath to retract and uncover the underlying endoluminal device. As the sheath retracts, the endoluminal device becomes free to expand. A control line is mechanically attached to the outer tube and serves to move the outer tube and retract the sheath.
None of these medical device assemblies utilize a control line that is integral with a confining sheath. Nor do these assemblies feature a sheath that is convertible to a control line as the sheath is removed from around the endoluminal device. Such an integral control line and confining sheath would preferably be made of a continuous thin-walled material or composite thereof. The thin-walled material would be flexible and exert minimal restrictions on the flexibility of an underlying endoluminal device. Thin-walled materials would also reduce the profile of the sheath and endoluminal device combination. An integral control line and confining sheath would simplify manufacture of control line—sheath constructs by eliminating the need to mechanically attach the control line to the sheath. An integral control line and confining sheath would also eliminate concerns regarding the reliability of the mechanical attachment of the control line to the sheath.
SUMMARY OF THE INVENTION
The present invention is directed to a deployment system for an expandable endoluminal device. In preferred embodiments, the endoluminal device is self-expanding as a consequence of the device design and the materials used to construct the device. In other embodiments, the endoluminal device is expanded with an inflatable balloon placed within the device. The endoluminal device is maintained in a compacted, or collapsed, configuration by a removable sheath. The sheath is removed from around the endoluminal device by pulling on a deployment line. The deployment line is an integral, continuous, extension of the sheath that is made of the same material as the sheath. As the deployment line is pulled, the sheath progressively retracts from around the endoluminal device and also functions as an extension of the deployment line. When the sheath has been substantially removed from around a portion of the endoluminal device, that portion of the endoluminal device is free to expand. Removal of the sheath may be continued until the entire endoluminal device is freed from radial constraint. The deployment line, along with any remaining sheath material, may be removed from the implantation site through the use of a catheter used to deliver the sheathed endoluminal device to the site.
The removable sheath is made of one or more thin, flexible polymeric materials including composites thereof. The sheath ordinarily assumes the form of a continuous thin-walled tube when constraining an endoluminal device. Such a thin-walled sheath exerts minimal resistance to longitudinal flexing of an underlying endoluminal device. The thin-walled sheath also reduces the profile of the sheath—endoluminal device combination, when compared to conventional constraints. In preferred embodiments, a double-walled tubular sheath is used. Double walls enable the sheath to be retracted from around an endoluminal device by rolling or sliding one wall past the other wall. As the sheath is retracted in this manner, the sheath portion does not rub or scrap against the endoluminal device. This is particularly advantageous when coatings containing medications or pharmaceuticals are placed on surfaces of the endoluminal device that may be removed by a sheath that rubs or scrapes against the endoluminal device during removal.
The deployment line is formed from the same material as the tubular sheath and is an integral extension of the sheath material. The deployment line extends from the sheath through a delivery catheter to a control knob located at the proximal end of the catheter. Pulling on the control knob actuates the deployment line. Once the deployment line is actuated, the removable sheath begins to retract from around the endoluminal device.
In one embodiment, as removed sheath material travels beyond the receding end of the sheath, the sheath begins to become converted to deployment line. Conversion of the sheath into the deployment line usually begins at a point where the tubular sheath breaks apart, separates, and converges into deployment line material. In preferred embodiments, means are provided for initiating or sustaining the conversion of the sheath to deployment line. These means may take the form of perforations, stress risers, or other mechanical weaknesses introduced into the sheath material. The means can also be cutting edges or sharp surfaces on the delivery catheter.
In preferred embodiments, materials and/or composites exhibiting compliance, compressibility, and/or resilience are placed between the endoluminal device and the delivery catheter. The compliant material serves to cushion the endoluminal device when constrained by the sheath and may assist in expansion of the device when unconstrained. The compliant material also serves to anchor and retain the endoluminal device in place on the underlying catheter shaft. When used in combination with a double-walled sheath, the compliant material can have tacky surfaces that further assist in anchoring and retaining the endoluminal device. In these embodiments, the tacky surface of the compliant material do not interfere with removal of the sheath from around an endoluminal device. The anchoring of the endoluminal device via the compliant material eliminates the need for barrier, or retention means at either end of the endoluminal device. The absence of barrier means also contributes to a reduction in the profile and an increase in flexibility of the distal portion of the assembly. The present invention can also be provided with an additional catheter or catheter lumen for the deployment line in order to prevent the deployment line from leaving the general path established by the delivery catheter.
Accordingly, one embodiment of the present invention is a deployment system for a self-expanding endoluminal device comprising a removable sheath adapted to cover the endoluminal device, the sheath comprising a thin continuous film adapted to surround at least a portion of the endoluminal device and constrain the device in an introductory profile, wherein the deployment system includes a deployment line integral with the sheath to effectuate device deployment, and wherein upon deployment, the sheath separates from the endoluminal device through actuation of the deployment line, the sheath becoming removed from the device along with the deployment line.
In another embodiment, the present invention is a deployment system for a self-expanding endoluminal device comprising a self-expanding endoluminal device at least partially enclosed by a removable sheath, and a deployment line integral with the sheath, wherein the sheath is convertible to the deployment line as the sheath is removed from the endoluminal device.
These enhanced features and other attributes of the deployment system of the present invention are better understood through review of the following specification.



BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 illustrates a longitudinal cross-section of the present invention.
FIG. 1A is an enlarged view of FIG. 1.
FIG. 2 illustrates a perspective view of the present invention.
FIG. 3 illustrates a longitudinal cross-section of the present invention.
FIG. 3A is an enlarged view of FIG. 3.
FIG. 4 illustrates a longitudinal cross-section of the present invention.
FIG. 4A is an enlarged view of FIG. 4.
FIG. 5 illustrates a longitudinal cross-section of the present invention.
FIG. 5A is an enlarged view of FIG. 5.
FIG. 6 illustrates a longitudinal cross-section of the present invention.
FIG. 6A is an enlarged view of FIG. 6.
FIG. 7 illustrates a longitudinal cross-section of the present invention.
FIG. 7A is an enlarged view of FIG. 7.
FIG. 7B illustrates the embodiment of FIG. 7A as viewed from the direction indicated by the arrow.
FIG. 7C illustrates the embodiment of FIG. 7A as viewed from the direction indicated by the arrow.
FIGS. 8 and 8A illustrate longitudinal cross-sections views of the present invention placed inside a vascular or cardiac structure.
FIG. 9 illustrates a longitudinal cross-section of the present invention with a covering placed over a compressible material.
FIG. 9A illustrates a longitudinal cross-section of the present invention without a covering placed over a compressible material.



DETAILED DESCRIPTION OF THE INVENTION
The present invention is directed to a deployment system for an expandable endoluminal device having a removable distal tubular sheath with a deployment line or filament that is an integral part of the sheath. The sheath radially confines the endoluminal device in a compacted or collapsed configuration during storage and introduction into a patient's vascular system. The confining sheath maintains the endoluminal device in a compacted configuration until the device is delivered with a catheter to an implantation site in a vascular or cardiac structure. As the deployment line is actuated, it pulls on the distal tubular sheath and begins to retract the sheath from the endoluminal device. In some embodiments, sheath material may be converted into deployment line material as the sheath is removed from the endoluminal device. As the distal tubular sheath is removed from the endoluminal device, the endoluminal device is free to expand. Once free from the confining sheath, the endoluminal device may expand spontaneously or with the assistance of an inflatable balloon. Any remaining sheath material may be removed from the implantation site along with the deployment line.
The integral sheath—deployment line is preferably a flexible polymeric material that is continuous along the length of the construct. Preferably, the physical and mechanical properties of the sheath portion are such that they are uniform and homogeneous throughout the length of the sheath portion used to constrain the endoluminal device. Since most endoluminal devices are generally circularly cylindrical in form, the sheath is preferably tubular in shape in order to enclose most or all of the endoluminal device. Conical, tapered, or other suitable shapes for the sheath are also contemplated in the present invention. Flexibility of the sheath is enhanced by making the walls of the sheath as thin as practicable. In one embodiment of the present invention (20), the tubular sheath portion (12a) of the sheath deployment line has a single wall (FIG. 3). The deployment line portion can extend from either end of the single-walled sheath (12a). When the sheath portion is retracted from around an endoluminal device, the length of retracted sheath is substantially equal to the length of deployment line displaced during deployment of the endoluminal device.
In another embodiment of the present invention (10), the sheath portion (12) of the sheath—deployment line has a double wall (FIGS. 1–2). In a preferred embodiment, the double walled-sheath portion (12) is made of a polymeric material that is folded on itself. The double-walled sheath portion is placed over the endoluminal device so that the fold (22) is positioned at the distal end of the sheath portion. The inner wall of the sheath portion may be anchored to part of an underlying delivery catheter (19) proximal to the endoluminal device (14). In preferred embodiments, the sheath portion is not attached to the delivery catheter. The proximal end of the outer wall of the sheath has at least one portion, or integral extension, that is convertible to deployment line (16). Space between the walls of the double-walled sheath portion can be filled with fluids, lubricants, pharmaceutical compositions, and/or combinations thereof. The deployment line (16) is routed through the delivery catheter (19) to a control knob (not shown) located at the distal end of the deployment system (10). Alternatively, a separate catheter (13) or catheter lumen (11) is provided for the deployment line (FIGS. 4 and 1, respectively). These embodiments provide additional containment of the deployment line portion, particularly when bends or curves in a patient's vasculature having small radii are anticipated. Preferably, the physical and mechanical properties of the sheath portion are such that they are uniform and homogeneous throughout the length of the sheath portion used to constrain the endoluminal device. When the sheath portion is retracted from around an endoluminal device, the length of retracted sheath is essentially half the length of deployment line displaced during deployment of the endoluminal device. This two to one ratio of length of deployment line removed to length of sheath material removed reduces the effect of too rapid or strong a pull on the deployment line on release of the endoluminal device from the sheath.
Fluoropolymer materials are preferred for making the retractable tubular constraining sheath—deployment line constructs of the present invention. Fluoropolymer materials used in the present invention are strong, thin, and lubricious. The lubriciousness of the fluoropolymer materials is especially advantageous in embodiments utilizing a sheath—deployment line having walls that slide past one another or over an endoluminal device. Particularly preferred fluoropolymer materials are porous expanded polytetrafluoroethylene materials alone or in combination with fluorinated ethylene propylene materials. Most preferred fluoropolymer materials are strong and thin, such as those described in Example 2, infra. The sheath—deployment line is made by constructing an appropriate tube from layers of film and membrane. A significant portion of this tube is then rendered filamentous by rolling and heating.
The sheath may be converted to deployment line by pulling on the deployment line and causing the sheath material to separate and converge into a single filament. As sheath material is converted to deployment line by this process, the edge of the sheath supplying material to the deployment line recedes causing the sheath to retract from around the endoluminal device. As a portion of the sheath retracts, the portion of the endoluminal device confined by the sheath is freed to expand (FIGS. 8–8A). Means are optionally provided to the deployment system that initiate or sustain the conversion of sheath to deployment line. As shown in FIG. 7, the means include perforations (71), cutouts (72), or other engineered defect introduced into the sheath material. As shown in FIG. 5, the means also include cutters (21) or other sharp edges on the delivery catheter. Such cutting means may be formed on the delivery catheter by exposing a strand of reinforcing stainless steel from within the catheter and adapting the strand to cut into the sheath portion.
In the preferred embodiment of the present invention, materials and/or composites exhibiting compliance, compressibility, and/or resilience are placed between the delivery catheter and the endoluminal device. Preferably, the compliant material is also compressible. At least a portion of the endoluminal device is pressed into the compressible material to anchor the endoluminal device on the delivery catheter and prevent the endoluminal device from moving along the length of the catheter. Materials with a tacky surface are useful in this embodiment, particularly in combination with a lubricious sheath material. The compressible anchor material eliminates the need for barrier, or retention, means placed at the proximal and distal end of the endoluminal device. In addition to added flexibility imparted to the deployment system without the barrier means, the profile of the sheath and endoluminal device combination is reduced without the barrier means. In the most preferred embodiment, the compressible material also has resilience that assists in expanding the endoluminal device following removal of the confining sheath. Suitable materials for the compressible material include, but are not limited to, silicones, silicone foams, polyurethane, polyurethane foams, and polytetrafluoroethylene foams. The compressible material is attached to the outer wall of the delivery catheter with adhesives, heat, or other suitable means.
The compressible material is preferably enclosed with a polymeric material (15). The polymeric material is preferably a fluoropolymer-based material. Porous expanded polytetrafluoroethylene is the preferred fluoropolymer for enclosing the compressible material. Other suitable polymeric materials include, but are not limited to, silicone, polyurethane, and polyester.
EXAMPLES
Example 1
This example describes the construction of a deployment system of the present invention. Construction of the system began with the preparation of a distal catheter shaft for receiving an expandable stent. Once the distal catheter was prepared, the expandable stent was placed within a sheath—deployment line. The distal catheter portion of this combination was attached to a primary catheter shaft. The deployment line portion was then routed through the primary catheter to a control knob. The control knob was part of a hub located proximally on the primary catheter. The sheath portion of the sheath—deployment line was in the form of a single-walled tube.
A tubular material three inches long was obtained from Burnham Polymeric, Inc., Glens Falls, N.Y. for use as the distal catheter shaft. The tube was made of a polyether block amide material, commonly known as PEBAX® resin and reinforced with a stainless steel braid. The outer diameter (OD) was 1.01 mm and the inner diameter (ID) was 0.76 mm. A compressible material in the form of a cushion was then placed on the catheter. To place the cushion on the catheter, the catheter was mounted on a mandrel having an outer diameter of 0.74 mm. A film of porous expanded polytetrafluoroethylene (ePTFE) was obtained according to the teachings in U.S. Pat. No. 5,814,405, issued to Branca, which is incorporated herein by reference. A discontinuous coating of fluorinated ethylene propylene (FEP) was applied to one side of the ePTFE material in accordance with U.S. Pat. No. 6,159,565, issued to Campbell et al., and incorporated herein by reference. An edge of the ePTFE-FEP composite film two inches wide was attached with heat to the catheter shaft. After initial attachment, the film was wrapped around the catheter shaft forty-five (45) times under light tension. With every fifth wrap of the film, and on the final layer, the film is further attached to itself with heat. This procedure provides a compressible material, or compliant “pillow,” on the distal catheter shaft. The expandable stent is mounted over the compressible material. The compressible material provides a means of retaining an expandable stent on the catheter shaft during storage, delivery to an implantation site, and deployment of the expandable stent at the implantation site. Optionally, the compressible material may be reinforced with a thin coating of an elastomeric material such as silicone, urethane, and/or a fluoroelastomer.
An eight (8) cell, 6 mm diameter, nitinol stent was obtained from Medinol Ltd., Tel-Aviv, Israel. The stent was placed over the compressible material of the catheter in an expanded state. The combination was placed within a machine having a mechanical iris that compacts or compresses the stent portion of the assembly onto the compressible material. While retained in the mechanical iris machine, the stent was reduced in temperature from room temperature to approximately five degrees centigrade (5° C.). At the reduced temperature, the iris machine was actuated to compact, or collapse, the stent onto the compressible material. While in the refrigerated and compressed configuration, the catheter, compressible material, and stent were placed within a sheath—deployment line of the present invention.
The sheath—deployment line having a length equal to, or greater than, the length of the final deployment system was made as follows. A stainless steel mandrel measuring 1.73 mm in diameter was covered with a sacrificial layer of ePTFE. The sacrificial ePTFE material aids in removal of the sheath—deployment line from the mandrel. Two wraps of a thin polytetrafluoroethylene (PTFE) membrane were applied to the mandrel. The ePTFE membrane was applied so the primary strength of the film was oriented parallel with the longitudinal axis of the mandrel. The membrane was initially tacked in place with heat applied with a soldering iron. The membrane thickness measured about 0.0002′′ (0.005 mm) and had tensile strengths of about 49,000 psi (about 340 KPa) in a first direction and of about 17,000 psi (about 120 KPa) in a second direction (perpendicular to the first direction). The tensile measurements were performed at 200 mm/min. load rate with a 1′′ (2.5 cm) jaw spacing. The membrane had a density of about 2.14 g/cm3. This membrane was further modified by the application of an FEP coating on one side in accordance with U.S. Pat. No. 6,159,565, issued to Campbell et al., which is incorporated herein by reference. Next, two wraps of the same ePTFE membrane were applied to one end of the construction (approx. 1′′ wide). These two wraps had the primary strength direction of the film oriented perpendicular to the mandrel's longitudinal axis. These layers of film provide additional “hoop” or “radial” strength to the sheath—deployment line construct. The mandrel and sheath—deployment line construct were placed in an air convection oven obtained from The Grieve Corporation, Round Lake, Ill., and subjected to a thermal treatment of 320° C. for 12 minutes. After air cooling, the ePTFE/FEP tube construct was removed from the mandrel and the sacrificial ePTFE layer removed. The construct was then attached to a primary catheter shaft using heat and standard materials.
The deployment line portion of the sheath—deployment line was made by splitting the sheath—deployment line along its length from a proximal end up to, but not including, the sheath portion enclosing the stent. The material thus obtained was gathered into a filament by rolling the material. Heat was applied to the material to set the material in the filamentous form. The deployment line filament was routed through a lumen in the primary catheter and connected to a control knob. The control knob was part of a hub located at the proximal end of the primary catheter. When the deployment line portion of the sheath—deployment line was pulled, the sheath portion was retracted from around the stent.
Example 2
This example describes the construction of a deployment system of the present invention. Construction of the system begins with the preparation of a distal catheter shaft for receiving an expandable stent. Once the distal catheter was prepared, the expandable stent was placed within a sheath—deployment line. The distal catheter portion of this combination was attached to a primary catheter shaft. The deployment line portion was then routed through the primary catheter to a control knob. The control knob was part of a hub located proximally on the primary catheter. The sheath portion of the sheath—deployment line was in the form of a double-walled tube.
A tubular material three inches long was obtained from Burnham Polymeric, Inc., Glens Falls, N.Y. for use as the distal catheter shaft. The tube was made of a polyether block amide material, commonly known as PEBAX® resin and reinforced with a stainless steel braid. The outer diameter (OD) was 1.01 mm and the inner diameter (ID) was 0.76 mm. A compressible material in the form of a cushion was then placed on the catheter. To place the cushion on the catheter, the catheter was mounted on a mandrel having an outer diameter of 0.74 mm. A film of porous expanded polytetrafluoroethylene (ePTFE) was obtained according to the teachings in U.S. Pat. No. 5,814,405, issued to Branca, which is incorporated herein by reference. A discontinuous coating of fluorinated ethylene propylene (FEP) was applied to one side of the ePTFE material in accordance with U.S. Pat. No. 6,159,565, issued to Campbell et al., which is incorporated herein by reference. An edge of the ePTFE-FEP composite film two inches wide was attached with heat to the catheter shaft. After initial attachment, the film was wrapped around the catheter shaft forty-five (45) times under light tension. With every fifth wrap of the film, and on the final layer, the film is further attached to itself with heat. This procedure provides a compressible material, or compliant “pillow,” on the distal catheter shaft. The expandable stent is mounted over the compressible material. The compressible material provides a means of retaining an expandable stent on the catheter shaft during storage, delivery to an implantation site, and deployment of the expandable stent at the implantation site. Optionally, the compressible material may be reinforced with a thin coating of an elastomeric material such as silicone, urethane, and/or a fluoroelastomer.
An eight (8) cell, 6 mm diameter, nitinol stent was obtained from Medinol Ltd., Tel-Aviv, Israel. The stent was placed over the compressible material of the catheter in an expanded state. The combination was placed within a machine having a mechanical iris that compacts or compresses the stent portion of the assembly onto the compressible material. While retained in the mechanical iris machine, the stent was reduced in temperature from room temperature to approximately five degrees centigrade (5° C.). At the reduced temperature, the iris machine was actuated to compact, or collapse, the stent onto the compressible material. While in the refrigerated, compressed configuration, the catheter, compressible material, and stent were placed within a sheath—deployment line of the present invention.
The sheath—deployment line having a length equal to, or greater than, the length of the final deployment system was made as follows. A stainless steel mandrel measuring 1.73 mm in diameter was covered with a sacrificial layer of ePTFE. The sacrificial ePTFE material aids in removal of the sheath—deployment line from the mandrel. Two wraps of a thin, polytetrafluoroethylene (PTFE) membrane were applied to the mandrel. The ePTFE membrane was applied so the primary strength of the film was oriented parallel with the longitudinal axis of the mandrel. The film was initially tacked in place with heat applied with a soldering iron. The membrane thickness measured about 0.0002′′ (0.005 mm) and had tensile strengths of about 49,000 psi (about 340 KPa) in a first direction and of about 17,000 psi (about 120 KPa) in a second direction (perpendicular to the first direction). The tensile measurements were performed at 200 mm/min. load rate with a 1′′ (2.5 cm) jaw spacing. The membrane had a density of about 2.14 g/cm3. The membrane was further modified by the application of an FEP coating on one side in accordance with U.S. Pat. No. 6,159,565, issued to Campbell et al., which is incorporated herein by reference. Next, two wraps of another ePTFE film made according to the teachings of Bacino in U.S. Pat. No. 5,476,589 and further modified with a discontinuous layer of an FEP material applied to one side of the EPTFE film were applied to one end of the construction (approx. 1′′ wide). U.S. Pat. No. 5,476,589 is incorporated herein by reference. These two wraps had the primary strength direction of the film oriented perpendicular to the mandrel's longitudinal axis. These layers of film provide additional “hoop” or “radial” strength to the sheath—deployment line construct. The mandrel and sheath—deployment line construct were placed in an air convection oven obtained from The Grieve Corporation, Round Lake, Ill., and subjected to a thermal treatment of 320° C. for 12 minutes. After air cooling, the ePTFE/FEP tube construct was removed from the mandrel and the sacrificial ePTFE layer removed. In this example, a length of sheath—deployment line extending beyond the end of the stent was provided. The additional length of sheath—deployment line was folded back over sheath portion enclosing the stent to form a double-walled construct. The double-walled sheath—deployment line had an inner wall and an outer wall. The inner wall was against the stent and the outer wall included the integral deployment line portion of the construct. The construct was then attached to a primary catheter shaft using heat and standard materials.
The deployment line portion of the sheath—deployment line was made by splitting the sheath—deployment line along its length from a proximal end up to, but not including, the sheath portion enclosing the stent. The material thus obtained was gathered into a filament by rolling the material. Heat was applied to the material to set the material in the filamentous form. The deployment line filament was routed through a lumen in the primary catheter and connected to a control knob. The control knob was part of a hub located at the proximal end of the primary catheter. When the deployment line portion of the sheath—deployment line was pulled, the sheath portion was retracted from around the stent.
Example 3
This example describes the incorporation of a means for initiating or maintaining conversion of the sheath portion of the sheath—deployment line to deployment line by introducing perforations and intentional stress risers into the sheath.
The sheath—deployment line from Example 2 is modified as follows. Prior to rolling the sheath portion into a double-walled construct and loading the stent therein, the sheath is perforated and/or supplied with “stress risers” that facilitate in separation of the tubular sheath upon retraction of the deployment line portion. An appropriate laser for making the perforations or stress risers is a 20 watt CO2 laser obtained from Universal Laser Systems, Scottsdale, Ariz. To form the perforations in the sheath portion, the sheath is placed on a sandblasted stainless steel mandrel and exposed to the laser to cut a series of holes in a part of the tube that will subsequently serve as the outer wall of the double-walled construct. The geometry of the holes can be varied depending on the application. The perforated sheath portion is used on a deployment line system of the present invention as described in Example 2. In this example, tension applied to the deployment line portion at the hub end of the catheter results in retraction of the sheath from around the stent and also results in parting the sheath at the perforations. As the sheath portion is separated, the sheath material becomes convertible to deployment line.
Example 4
This example describes the incorporation of a means for initiating or maintaining conversion of the sheath portion of the sheath—deployment line to deployment line by the use of an appropriate splitting means.
The primary catheter from Example 2 is modified as follows. The primary portion of the catheter is provided with a notch in the wall in 180 degrees opposition and slightly distal to the entry point of the deployment line portion into the catheter lumen. The notch is further modified to provide a small cutting edge in the notch. In one embodiment, the cutting edge is simply attached to the notch with heat, adhesives, and the like. In another embodiment, the cutting edge is formed by exposing a portion of a metallic braid used to reinforce the catheter shaft and forming the braid into a cutting edge. In this example, tension applied to the deployment line portion at the hub end of the catheter results in retraction of the sheath from around the stent and also results in parting the sheath at the perforations. As the sheath portion is separated, the sheath material becomes convertible to deployment line.

## Claims

1. A deployment system for a self-expanding endoluminal device comprising:
a removable sheath adapted to cover the endoluminal device, the sheath comprising a thin continuous film in the form of a double-walled tubular construct adapted to surround at least a portion of the endoluminal device and constrain the device in an introductory profile;
wherein the deployment system includes a deployment line integral with the sheath to effectuate device deployment;
wherein upon deployment, the sheath separates from the endoluminal device through actuation of the deployment line, the sheath pulling away from the device along with the deployment line; and
a compressible construct placed between the endoluminal device and a delivery catheter underlying the endoluminal device, wherein the sheath splits to transform from the sheath to an elongated filament.

2. The deployment system of claim 1 wherein means is provided to aid in splitting from a sheath to the filament.

3. The deployment system of claim 1 wherein the means to aid In splitting comprises a splitter.

4. The deployment system of claim 1 wherein the means to aid in splitting comprises an engineered defect incorporated into the sheath deployment line.

5. The deployment system of claim 1 wherein the sheath comprises a wall with a thickness of less than 0.05 mm.

6. The deployment system of claim 1 wherein the sheath comprises a continuous film that surrounds the endoluminal device in a double layer.

7. The deployment system of claim 6 wherein one layer of the double layer is placed over the other layer and one layer move past the other layer upon deployment.

8. The deployment system of claim 1 that includes a single catheter shaft.

9. The deployment system of claim 8 wherein the catheter shaft extends beyond the endoluminal device in its introductory profile.

10. The deployment system of claim 1 wherein the compressible construct is also resilient.

11. The deployment system of claim 1 wherein the length of sheath retracted from the self-expanding endoluminal device is substantially equal to the length of deployment line displaced during deployment of the self-expanding endoluminal device.

12. The deployment system of claim 1 wherein the length of sheath retracted from the self-expanding endoluminal device is essentially half the length of deployment line displaced during deployment of the self-expanding endoluminal device.

13. The deployment system of claim 1 wherein the sheath is not attached to a catheter shaft.