Classifications

• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
  • A61F2/00—Filters implantable into blood vessels; Prostheses, i.e. artificial substitutes or replacements for parts of the body; Appliances for connecting them with the body; Devices providing patency to, or preventing collapsing of, tubular structures of the body, e.g. stents
  • A61F2/95—Instruments specially adapted for placement or removal of stents or stent-grafts
  • A61F2/962—Instruments specially adapted for placement or removal of stents or stent-grafts having an outer sleeve
  • A61F2/966—Instruments specially adapted for placement or removal of stents or stent-grafts having an outer sleeve with relative longitudinal movement between outer sleeve and prosthesis, e.g. using a push rod
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
  • A61B17/00—Surgical instruments, devices or methods
  • A61B17/34—Trocars; Puncturing needles
  • A61B17/3468—Trocars; Puncturing needles for implanting or removing devices, e.g. prostheses, implants, seeds, wires
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
  • A61F2/00—Filters implantable into blood vessels; Prostheses, i.e. artificial substitutes or replacements for parts of the body; Appliances for connecting them with the body; Devices providing patency to, or preventing collapsing of, tubular structures of the body, e.g. stents
  • A61F2/95—Instruments specially adapted for placement or removal of stents or stent-grafts
  • A61F2/962—Instruments specially adapted for placement or removal of stents or stent-grafts having an outer sleeve
  • A61F2/97—Instruments specially adapted for placement or removal of stents or stent-grafts having an outer sleeve the outer sleeve being splittable
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
  • A61B17/00—Surgical instruments, devices or methods
  • A61B17/34—Trocars; Puncturing needles
  • A61B17/3417—Details of tips or shafts, e.g. grooves, expandable, bendable; Multiple coaxial sliding cannulas, e.g. for dilating
  • A61B17/3421—Cannulas
  • A61B2017/3435—Cannulas using everted sleeves
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
  • A61F2/00—Filters implantable into blood vessels; Prostheses, i.e. artificial substitutes or replacements for parts of the body; Appliances for connecting them with the body; Devices providing patency to, or preventing collapsing of, tubular structures of the body, e.g. stents
  • A61F2/95—Instruments specially adapted for placement or removal of stents or stent-grafts
  • A61F2/962—Instruments specially adapted for placement or removal of stents or stent-grafts having an outer sleeve
  • A61F2/966—Instruments specially adapted for placement or removal of stents or stent-grafts having an outer sleeve with relative longitudinal movement between outer sleeve and prosthesis, e.g. using a push rod
  • A61F2002/9665—Instruments specially adapted for placement or removal of stents or stent-grafts having an outer sleeve with relative longitudinal movement between outer sleeve and prosthesis, e.g. using a push rod with additional retaining means

Definitions

• the present invention relates to apparatus used to position and deploy medical diagnostic and treatment devices in a body.
• a growing number of medical diagnostic and treatment devices are being developed that are remotely used to assess and/or treat patients, typically being guided to a target site using imagining technology such as fluoroscopes or ultrasound.
• imagining technology such as fluoroscopes or ultrasound.
• Such devices include stents, stent-grafts, balloons, blood filters, occluders, probes, valves, electronic leads, orthopedic devices, etc.
• Radiopaque markers or similar indicia are often used to allow the medical staff to exactly position the medical device using the imagining technology.
• the medical staff will then carry out the procedure and/or deploy the necessary device or devices. Since most of these procedures, such as interventional treatment of occlusions or aneurysms, require exact placement of a treatment device, it is important that the device deploys in the same position where it had been initially placed. For instance, in treating aortic aneurysms with a stent-graft, physicians expect displacement of the device of less than 5 mm following deployment. Any greater displacement may result in endoleaks, blocked side vessels, or other complications requiring otherwise unnecessary further treatments or even risky conversion to open surgery.
• a similar concept to the original catheter tube constraint is to use a thin sheath of material that is pulled back over the treatment device while holding the device in place.
• One advantage of this concept is that the device and thin sheath can take up considerably less space than housing a device within a relatively bulky catheter tube.
• the thin sheaths also can provide greater flexibility over much stiffer catheter tube materials. Such compactness and flexibility are highly desirable as physicians try to reach tighter treatment sites through smaller and more tortuous vessels.
• this method can put considerable strain on a self-expanding device, which is exerting pressure against the constraining sheath throughout the deployment process.
• the resulting friction between the device and the sheath often requires application of considerable tensile force to remove the sheath, making ultimate exact positioning much more difficult, as well as possibly damaging the treatment device in the process of sheath removal.
• One deployment method to limit such effects is to employ a thin sheath of material that is everted over itself, so that the constraining sheath rubs only against itself while it is being pulled back over a self-expanding device.
• a sheath of a given diameter is everted back over itself and then pulled down the length of the sheath through the deployment procedure.
• Variations on this concept are described in, for instance, US Patent 4,732,152 to Wallsten, US Patent 5,571 ,135 to Fraser et al., US Patent 6,942,682 to Vrba et al., and US Application 2006/0025844 to Majercak et al., and US Patent Application 2006/0030923 to Gunderson.
• these methods offer the prospect of compactness with less strain placed on the treatment device and perhaps more precise device placement.
• everting sheaths address some of the complications seen with non-everting sheaths, they still can require considerable tension in order to pull the sheath over itself and the self-expanding device during deployment, resulting mainly from the friction of everted portion of the sheath rubbing against the non-everted portion of the sheath while the sheath is being removed. These concerns are compounded with longer device lengths and more robust self-expanding devices that exert greater outward pressures. The greater the tension needed to evert and remove the sheath, the more demanding it is for the medical staff to remove the sheath while trying to hold the apparatus in its exact position during deployment. Increased deployment tensions also require more substantial sheath constructions so as to avoid sheath and deployment line breakage during deployment. It is believed that these deficiencies of everting sheaths may have limited practical applications for such deployment methods.
• the present invention is directed to a deployment sheath for medical devices that includes one or more pleats in its pre-deployment state that are allowed to open during deployment so as to facilitate easier sheath removal.
• the sheath is deployed by everting it over itself during the delivery process.
• the sheath undergoes a predictable enlargement during device deployment so as to relieve friction of the everted sheath sliding along itself during deployment. This allows the sheath to be removed with considerably less tension than previous everting sheath constructions and assures more accurate device placement in a patient.
• the sheath may be used to deliver an endoprosthesis.
• the sheath may be tubular in construct and includes at least one pleat oriented along at least a portion of its length, preferably helically along its length.
• the pleat may incorporate a material or other feature that resists folding and tensile strain, such as a polyimide, to aid in creating and maintaining the pleat form and orientation.
• the sheath may be used to deploy a medical device with the sheath at least partially everted over itself to form an interior segment and an exterior segment in the pre-deployed configuration. At least one pleat is provided along at least a portion of the interior segment, again preferably in a helical orientation.
• the interior segment When deployment occurs by applying tension to the exterior segment of the sheath, the interior segment progressively reorients itself into the exterior segment with the pleat progressively opening as the sheath everts. This un-pleating of the sheath as it becomes the exterior segment allows the exterior segment to be of sufficiently greater diameter than the pleated interior segment so as to reduce frictional contact between the interior segment and the exterior segment during deployment.
• the sheath By minimizing the frictional contact of the sheath upon itself, it has been determined that the sheath can be removed with considerably less applied tension than has been required in prior sheath containment apparatus. Once again, it is preferred that the sheath incorporates a material or other feature that is resistant to folding and tensile strain to aid in pleat formation and maintenance.
• the deployment apparatus of the present invention may be used to deploy a wide variety of devices to diagnose and/or treat patients.
• Such devices may include stents, stent-grafts, balloons, blood filters, occluders, probes, valves, electronic leads (e.g., pacing or defibulator leads), orthopedic devices, etc.
• the deployment apparatus of the present invention may be modified to address many different device delivery and deployment needs. For instance, the number of pleats, the orientation of the pleats, the size and spacing of the pleats, pleat pitch, etc., can be adjusted to allow devices to deploy in different manners. Additionally, the sheaths of the present invention can be mounted in a variety of ways on devices to accommodate different deployment requirements, such as allowing a device to deploy off a catheter hub-to-tip, or tip-to-hub, or from a mid-point of a device outward in both directions.
• Figure 1 is a plan view of one embodiment of a medical device deployment system employing a pleated sheath of the present invention mounted near a distal end of a delivery catheter;
• Figure 2 is an enlarged perspective view of a distal end of a delivery catheter showing an everting pleated sheath of the present invention being withdrawn, progressively releasing a self-expanding stent contained therein;
• Figure 3 is a cross-section view along line 3-3 of Figure 2, showing only the pleated sheath component of the present invention
• Figure 4 is a perspective view of a portion of an everting pleated sheath of the present invention, showing the pleat unfolding during eversion of the sheath, the sheath being actuated by a deployment line;
• Figure 5 is a perspective view of another embodiment of a pleated sheath of the present invention comprising a single layer
• Figure 6 is a cross-section view along line 6-6 of the sheath of Figure 5;
• Figure 7 is a cross-section view of the sheath of Figure 5 following opening of the pleat, the sheath being of a greater effective diameter than the pleated orientation shown in Figure 6;
• Figure 8 is a perspective view of still another embodiment of a pleated sheath of the present invention comprising a single layer and having two pleats provided therein;
• Figure 9 is a cross-section view along line 9-9 of Figure 8.
• Figure 10 is a perspective view of another embodiment of a sheath of the present invention wherein the spacing and pitch of the element that will define the pleat is changed along the length of the sheath in order to provide a variable diameter along the sheath length after the pleat is formed;
• Figure 11 is a perspective view of the sheath of Figure 10 after it has been pleated
• Figure 12 is a perspective view of another embodiment of a sheath of the present invention wherein the width of the element that will define the pleat is changed along the length of the sheath;
• Figure 13 is a perspective view of the sheath of Figure 12 after it has been pleated
• Figure 14 is a longitudinal cross-section view of a delivery catheter incorporating a pair of sheaths of the present invention and containing a compacted device, the pair of sheaths being oriented to withdraw from the device in opposite directions from a point midway along the device;
• Figure 15 is an enlarged perspective view showing a stent-graft device being deployed from a midpoint by removing two sheaths of the present invention in opposite directions;
• Figure 16A is a longitudinal cross-section view of a distal portion of a catheter utilizing a sheath of the present invention, showing another embodiment of apparatus to remove the sheath;
• Figure 16B is a longitudinal cross-section view of a proximal portion the catheter shaft of Figure 16A;
• Figure 17A is a partially cut-way perspective view of a distal portion of a catheter utilizing a sheath of the present invention, showing still another embodiment of apparatus to remove the sheath;
• Figure 17B is a partially cut-way perspective view of a proximal portion the catheter shaft of Figure 17A;
• Figure 18 is a three-quarter isometric view of another single-layer sheath of the present invention including additional thickness of material along a portion of a monolithic structure to provide pleat reinforcement;
• Figure 19 is a three-quarter isometric view of still another single-layer sheath of the present invention including surface treatment of the sheath in order provide a defined pleat hinge line;
• Figure 20 is a cross-section view of another embodiment of a sheath of the present invention comprising a sheet of material that is formed into a tubular construct by interlocking pleats formed on edges of the sheet.
• the present invention employs a pleated deployment sheath for medical device containment and delivery, preferably for use with everting sheath delivery.
• One or more pleats are pre-formed into the sheath in its pre-deployment state and are allowed to open during deployment so as to facilitate easier sheath removal.
• the sheath undergoes a predictable enlargement during deployment and thus relieves friction of the everted sheath sliding along itself during deployment. This allows the sheath to be removed with considerably less tension than previous everting sheath constructions and assures more accurate device placement in a patient.
• FIG. 1 Shown in Figure 1 is one embodiment of a pleated sheath 10 of the present invention mounted near the end of a medical device deployment system 12.
• the deployment system comprises a catheter shaft 14 extending from a distal olive 16 to a control hub 18.
• a medical device such as a stent, stent-graft, balloon, blood filter, occluder, probe, valves, etc., may be contained in the sheath 10 to be deployed at a treatment site within a patient's body.
• the sheath 10 is everted over itself to form two layers, an exterior segment 20 which, in this embodiment, completely covers an interior segment 22.
• the exterior segment is split at its proximal end 24 to form a deployment line 26 that is fed into the catheter shaft through opening 28.
• the deployment line 26 is operatively connected to a deployment knob 30 on the hub 18.
• the sheath 10 may be formed from any material that is sufficiently strong both to constrain the device to be delivered and to withstand the tension of the removal process. It is desirable that the sheath 10 also be as thin and lubricious as possible so as to maintain a small device delivery profile and to facilitate the removal process. Since the sheath 10 is placed temporarily deep within a patient during delivery and deployment, it is likewise desirable that the sheath be formed from a biocompatible material. As is explained in greater detail below, suitable sheath materials may include: polytetrafluoroethylene (PTFE); expanded PTFE (ePTFE); fluorinated ethylene propylene (FEP), polyethylene teraphthalate (PET), nylon, polyurethane, polypropylene, polyester, etc.
• PTFE polytetrafluoroethylene
• ePTFE expanded PTFE
• FEP fluorinated ethylene propylene
• PET polyethylene teraphthalate
• nylon polyurethane, polypropylene, polyester, etc.
• the interior segment 22 includes a helical pleat 32 extending fully along its length.
• the pleat 32 comprises a fold in the material of the sheath that reduces the interior segment 22 of the sheath to a diameter smaller than the diameter of the exterior segment 20.
• a reinforcing material 34 may be layered over or otherwise attached to the sheath.
• such material is fold-resistant so that the pleat more readily holds its correct orientation along its entire length during the folding process and through sheath deployment.
• Suitable reinforcing materials may include: one or more strips of polymer material, such as polyimide, polyethylene teraphthalate (PET), nylon, polyurethane, or similar material, adhered to the sheath; a coating applied to the strip that hardens to provide the desired properties, such as providing sufficient stiffness/Young's Modulus and thickness to resist folding for a given helical pitch, pleat width, and effective diameter.
• polymer material such as polyimide, polyethylene teraphthalate (PET), nylon, polyurethane, or similar material
• each pleat refers to any fold or multiple folds in the sheath material that reduces the effective diameter of the sheath.
• each pleat comprises two folds that cause the sheath material to double back on itself.
• the pleat may comprise a single fold or multiple folds along an edge of a sheet of material, which may be interlocked, for instance as shown in Figure 20.
• a pleat may also be formed through a rolling, twisting, or accordion folding of a section of material or similarly storing material for later un-pleating during deployment.
• the sheath 10 everts over itself at a fold 36 at one end, in this embodiment at the distal end.
• the fold 36 may be oriented at either the distal end or the proximal end of the device, or anywhere in between.
• medical personnel will unscrew the deployment knob 30 and pull on the knob and connected deployment line to cause the sheath to progressively withdraw off of the contained device.
• the fold 36 will progress down the length of the contained device, steadily everting the interior segment 22 so that it becomes the exterior segment 20. In the process of everting, the pleat 32 will wrap around the fold 36 and open up.
• the un-pleated exterior segment 20 will always remain at a larger effective diameter than the pleated interior segment 22 of the sheath.
• the larger diameter exterior segment 20 slides easily over the interior segment 22 and is readily removed with minimal friction between the two layers.
• FIG. 2 The process of device delivery can be better seen in Figure 2.
• the interior segment 22 with its reinforced pleats 32 is shown exposed in cut-away.
• the pleats 32 open up along fold 36.
• Seen along the length of the exterior segment 20 are the strips of reinforcement material 34, now merely attached to the sheath 10 and no longer defining a pleat.
• a constrained self-expanding stent 38 is progressively deployed from this embodiment.
• Figure 4 shows the process of un-pleating with the contained pleats 32 shown in phantom and the un-pleated reinforcement material 34 shown exposed along the exterior segment 20. Again, transition occurs along fold 36.
• a deployment line 40 is connected to one end 42 of the exterior segment 20. Tension on the deployment line 42 actuates the sheath 10.
• FIG. 5 illustrates another embodiment of the present invention comprising a single layer sheath 10.
• the helically formed pleat 32 again includes a strip of reinforcement material 34.
• the pleat 32 causes the sheath 10 to have a given diameter of x.
• the diameter of the sheath 10 enlarges to increased diameter of y.
• the pleats of the present invention are preferably stable without a constraining force.
• a sufficiently rigid pleat with sufficient helical angle will be inherently stable and will remain in place even without an external constraint.
• constraints can be provided to help retain the pleats in position.
• the single layer sheath may be formed and then everted over itself, either partially or entirely, and then employed in the manner described above. The everted portion of the sheath will maintain the pleats in their folded configuration until the device is ready for deployment.
• the single layer sheath may be contained in another tubular structure to maintain the pleats in a folded configuration, such as through use of another sheath, a closely fitted catheter tube, or similar structure.
• the pleats can be joined to the sheath, such as through use of an adhesive, an adhered tape, a wrapped tape, a wrapped thread, or similar means, that will hold the pleats in position until the device is ready for deployment.
• a further method of deployment of a single layer sheath may include tensioning from the proximal end of the pleated tube (that is, the end closest to the clinician). When sufficient tension is applied, the pleat will unfold and the tube will increase diametrically allowing it to be translated relative to the device.
• FIG. 8 and 9 Illustrated in Figures 8 and 9 is a still another embodiment of a pleated sheath 10 of the present invention.
• the sheath 10 comprises a single layer and includes two pleats 32a, 32b therein.
• the pleats may be evenly aligned on opposite sides of the sheath 10, as shown, or may be placed in other orientations. It should be understood that depending on desired deployment specifications, the present invention can be practiced with one, two, three, four, five or more pleats along part or all of the sheath length.
• Figure 10 illustrates another embodiment of a sheath 10 of the present invention wherein the spacing 44a, 44b, 44c, 44d between pleating elements 32 varies along the length of the sheath 10.
• the pitch 46a, 46b, 46c, 46d, 46e of the helical wraps of the pleating elements 32 also varies along the length of the sheath 10.
• Each of these properties can be adjusted, independently or in cooperation, in device design so as to provide varying diameters along the length of the sheath after pleating. Diameter may be varied along the length of the sheath to accommodate non-cylindrical device profiles and/or produce variable sheath removal properties.
• Figure 11 depicts the sheath of Figure 10 after it has been pleated.
• the sheath and contained device provide a tapered profile, with the distal end 48 being a smaller diameter than the proximal end 50.
• width 52a, 52b, 52c of the pleating element is changed along the length of the sheath 10. Again, by changing pleat width, diameter can be varied along the length of the sheath to accommodate non- cylindrical device profiles and/or produce variable sheath removal properties.
• the pleated sheath can be formed with a variable diameter, producing either greater or lesser friction (depending on the direction of deployment) as the sheath is deployed along its length - making it either initially easier or more difficult to deploy the sheath.
• Figure 13 depicts the sheath of Figure 12 after it has been pleated.
• the sheath and contained device provide a tapered profile, with the distal end 48 being a smaller diameter than the proximal end 50.
• FIG. 14 Shown in Figure 14 is a delivery catheter incorporating a pair of sheaths of the present invention and containing a compacted device 38, the pair of sheaths 10a, 10b being oriented to withdraw from a compacted device 38 in opposite directions from a point midway along the device.
• Proximal sheath 10a runs along catheter shaft 14 to an actuation mechanism 54.
• Distal sheath 10b is withdrawn in the opposite direction (that is, towards the distal end of the catheter 14) and is inverted into the catheter shaft 14.
• the distal sheath 10b is likewise controlled by actuation mechanism 54.
• the two sheaths 10a, 10b are withdrawn simultaneously from the compacted device 38 to allow it to deploy from its middle outward.
• Such deployment may be useful in those instances where very rapid device deployment is sought and/or where it is desirable to minimize the effect of high volume of blood flow upon the device prior to full deployment (for instance, when a device is deployed in the aorta and it is desirous to have the upstream end of the device deploy last so as to avoid a "windsock" effect in the high- volume blood flow which may misalign device positioning).
• Figure 15 illustrates how a stent-graft device 38 can be deployed from its midpoint by removing two sheaths 10a, 10b. This deployment method would be preferred for placing a stent-graft device in a thoracic aorta or the like.
• each of the sheaths 10a, 10b independently of each other so that only part of the device is deployed at any given time. This can be readily accomplished by providing separate actuation mechanisms for each of the sheaths. It should be further appreciated that with respect to all of the embodiments of the present invention discussed herein it may be desirable to have sheath deployment occur either from the distal end of the catheter back or from the proximal end of the catheter forward, or with two or more deployment sheaths moving in opposite directions, as illustrated in the embodiments of Figures 14 and 15.
• FIGs 16A and 16B illustrate a deployment mechanism similar to the one shown in Figure 14.
• a single everted sheath 10 is provided constraining a device 38.
• the sheath 10 extends proximally within an outer casing 54 of catheter shaft 14, coaxially surrounding inner catheter shaft 56.
• the sheath 10 extends to the proximal end 58 of the catheter 14, where it can be actuated by a user.
• the sheath 10 is constructed from a material that will split longitudinally, such as through a pre-formed longitudinal line of perforations or similar weakening means 60, so that the sheath 10 can be removed from the inner shaft 56 by applying tension to tail 62, as is shown in Figure 16B.
• a strain relief 64 may be provided on the distal end of the outer casing 54 to assist in handling of the catheter 14 during placement and deployment.
• FIG. 17A and 17B Another deployment mechanism that may be used with the present invention is shown in Figures 17A and 17B.
• a dual lumen catheter 14 is provided, having a lumen 66 for housing inner shaft 56 and a lumen 68 designed to accept a deployment line 40.
• the deployment line 40 is integral with or attached to the sheath 10. The line 40 is actuated to cause the sheath 10 to withdraw in the manner previously described.
• the preferred sheath of the present invention for containing and deploying a self-expanding stent or stent-graft for vascular applications will be constructed of a thin, lubricous polymer material, such as an ePTFE multi-layer laminated film tube, with a thickness of 0.03 to 0.3 mm, and more preferably 0.05 to 0.12 mm.
• a thin, lubricous polymer material such as an ePTFE multi-layer laminated film tube, with a thickness of 0.03 to 0.3 mm, and more preferably 0.05 to 0.12 mm.
• the tube of the present invention is preferably as thin as possible while having strength properties that will withstand loading forces and effectively constrain the device until it is deployed.
• FIG. 18 illustrates a pleat reinforcement 70 that is formed from the same material as the sheath 10 itself.
• Such reinforcement 70 is achieved by providing a layer of additional material along a portion of the sheath circumference so as to provide defined fold lines 72a, 72b on either side of the raised reinforcement 70.
• This construct may be formed by extruding or otherwise adding additional material in the defined manner on the sheath and/or removing material from, or densifying material on, the remainder of the sheath 10 in order to leave a pleat reinforcement 70 of increased dimension.
• a similar effect may be achieved by densifying the reinforcement area in order to establish fold-resistance.
• FIG 19 illustrates another approach to achieve predictable sheath folding.
• the sheath 10 has been treated to provide one or more defined pleat hinge lines 74a, 74b.
• Each hinge line 74 may be formed through any of a variety of surface treatment means, including through mechanical methods (e.g., cutting, scoring, densification, etc.), through extrusion or other material manufacture steps, or through thermal processing (e.g., through heat or laser treatment), or some combination of such various methods.
• the pleated configuration of the sheath 10 is folded along these hinge lines 74.
• FIG. 20 illustrates still another method of forming a pleat in accordance with the present invention.
• the sheath 10 is formed from a sheet of material having two edges 76a, 76b. Each of these edges 76a, 76b can then be folded to form a pleat 78a, 78b with one or more folds.
• the edge pleats 76a, 76b can then be interlocked with one another, for instance as shown, to create a tubular structure that serves as the sheath 10 of the present invention.
• the edges 76 will separate from each other to provide the desired predictable enlargement of the present invention.
• One or both of the edges 76 can be provided with reinforcement 80a, 80b, such as through one of the methods previously described, in order to facilitate the formation and retention of the pleat 78.
• the exterior segment in the final construct should have an inner diameter that is sufficiently greater than the outer diameter of the interior segment in order to minimize friction between the two segments. That is, in order to minimize interference between the interior segment and the exterior segment, the un-pleated exterior segment should enlarge enough so that its inner diameter comfortably clears the outer diameter of the pleated interior segment. It is preferred that the inner diameter of the exterior segment be 0.1 to 50 % larger than the outer diameter of the interior segment, and more preferably 10 to 20 % larger.
• a sheath with a wall thickness of about 0.08 mm and an un-pleated a inner diameter of about 2.1 mm will typically be provided with one or more pleats with a pleat width of 0.8 mm to create a pleated interior segment having a outer diameter of about 1.9 mm.
• pleats are provided with a width of 0.3 to 2.0 mm, and more preferably with a width range of 0.6 to 1.3 mm.
• Pleats will typically be oriented helically around the sheath, with a typical pitch angle of 30 to 75 degrees, and more preferably a pitch of 50 to 70 degrees.
• the pleats are preferably reinforced with a strip or strips of relatively fold-resistant material, such as polyimide film, with a thickness of 0.01 to 0.08 mm, and more preferably 0.02 to 0.05 mm.
• the reinforcement material is encapsulated between layers of a laminated sheath, adhered using an adhesive such as FEP or similar material.
• the preferred sheath of the present invention includes one or more pleats helically oriented along part or all of the longitudinal length of the sheath, it should be appreciated that other pleat orientations as likewise contemplated by the present invention. For example, so long as they are adequately constrained or adhered the pleat or pleats may be arranged essentially parallel to the axis of the device. Further, for some applications multiple discontinuous pleats may be provided to achieve suitable deployment properties. Additionally, for some applications it may be desirable to provide pleats along at least a portion of both the interior segment and the exterior segment of the sheath.
• the sheath of the present invention has been determined to vastly reduce the amount of tension required to deploy a device.
• deployment tensions are typically on the order of 50 - 150 grams
• a 1" (25.4 mm) wide strip of expanded polytetrafluoroethylene (ePTFE) film (having predominantly longitudinally oriented strength, film thickness of approximately 0.006 mm and break strength of approximately 0.8 kg / cm width) was "cigarette” wrapped on a 0.11" (2.8 mm) diameter x 40 cm long mandrel.
• the film structure was orientation parallel to mandrel axis so that the film was stronger parallel to the mandrel's longitudinal axis.
• a second layer of 0.4" (10 mm) wide ePTFE/FEP laminate film (predominantly longitudinally oriented strength, total film thickness of approximately 0.003 mm, FEP thickness of approximately 0.001 mm and break strength of approximately 0.7 kg / cm width) was then helically overwrapped around the first film layer with a single pass at a 0.2" (5 mm) pitch, to create a double thickness of the second film layer.
• the oriented film structure of the second layer was aligned in the helical direction around the mandrel.
• the tube was helically pleated by manually flipping the polyimide strip 180°. Approximately 11 cm of the tube was pleated with the pleat originating at one end of the tube, open side of the pleat facing away from the un-pleated section. Pleated inside diameter of the tube was approximately 0.095" (2.4 mm) with the helical pleat having a pitch of about 0.23" (5.8 mm). Approximately 14 cm of the tube was left un-pleated.
• a long stainless steel nozzle (approximately 100mm length, 0.095" (2.4 mm) outer diameter, 0.088" (2.2 mm) inner diameter) was fixed to the small end of a stainless steel loading funnel.
• the funnel was sized with a wide opening of approximately 14 mm diameter, a small funnel opening of approximately 2.2 mm diameter and a straight taper approximately 34 mm in length.

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• 2008
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