VARIABLE WALL THICKNESS FOR DELIVERY SHEATH HOUSING
A delivery sheath for an intravascular emboli capturing filter including an elongate tube having a distal region having a reduced thickness distal wall region. The delivery sheath, according to the present invention, can have a thinner, softer, distal most portion for superior and more benign interaction with vessel interior walls. The present invention includes an intravascular emboli filter system including an elongate shaft having a distal region, an expandable emboli filter operably coupled to the elongate shaft distal region, and an elongate sheath having a lumen therethrough disposed over the elongate shaft. The elongate sheath can have a distally decreasing outside diameter taper or reduced wall thickness region having improved atraumatic characteristics.
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This application is a continuation application of U.S. application Ser. No. 10/749,270 filed Dec. 31, 2003, which is a continuation application of U.S. application Ser. No. 09/770,030 filed Jan. 25, 2001, now U.S. Pat. No. 6,689,151.
FIELD OF THE INVENTIONThe present invention is related generally to medical devices. More specifically, the present invention includes tubular sheaths for delivering intravascular blood filtering devices.
BACKGROUND OF THE INVENTIONBlood vessels can become occluded in several ways. In one situation, a stenosis may be formed of an atheroma which can include a calcified material formed on the lumen walls of the blood vessel. In another situation, a stenosis can be formed of a thrombosis material which is typically softer than the calcified material, but can cause sudden and unpredictable blood flow reduction in a blood vessel lumen.
Different procedures have been developed to treat a stenotic lesion or stenosis in the vasculature. One method includes deforming the stenosis to reduce the restriction within the lumen of the blood vessel. This type of deformation is typically performed using balloon angioplasty. Another method includes the attempted removal of the stenosis or part of the stenosis. Removal of the stenotic lesion can be attempted through use of atherectomy, which can include mechanical ablation, radio frequency energy removal, and laser removal. In these methods, the stenosis can be mechanically cut or ablated from the vessel.
Problems may be encountered by the treating physician during thrombectomy and atherectomy. Stenotic debris, which may be separated from the stenosis, may be freed within the lumen of the vessel. If the debris flows distally, it can occlude distal vasculature and cause problems. If it flows proximally, it can enter the circulatory system which is also undesirable.
One technique for dealing with such debris includes filtering or otherwise removing the debris from within the vessel using an intravascular capture device. In one such method, a filtering device may be disposed distal of the stenosis during an atherectomy to catch the emboli or pieces of stenosis as they are released. These pieces or emboli may be removed using the capture device when the atherectomy procedure is complete. One such capture device includes a distal expandable filter member which can be placed distal of the stenosis to capture stenosis fragments. Expandable devices may be delivered through a delivery sheath and/or guide catheter to the treatment site. The delivery sheath and/or guide catheter may be retracted proximally prior to deploying the filter. After use, the filter may be retracted into the delivery sheath or guide catheter for removal.
What would be desirable are improved delivery sheaths for delivering distal protection devices to the treatment site. In particular, more benign delivery sheaths with distal ends that are easier to steer would be desirable.
SUMMARY OF THE INVENTIONThe present invention includes delivery sheaths for intravascular emboli capturing filters, the sheath including an elongate tube having a distal region wall that is distally decreasing in thickness. In one embodiment, the distally decreasing wall thickness is imparted at least in part by a distally decreasing outside sheath diameter. In some embodiments, a tapered distal region forms a region of increasing softness relative to the more proximal adjacent region. One example of an expandable emboli filter is provided by U.S. Pat. No. 5,827,324, herein incorporated by reference.
The present invention includes intravascular emboli filtering systems including an elongate shaft having an expandable emboli filter operably coupled to the shaft distal region. The system can further include an elongate sheath having a lumen therethrough for slidably accepting the expandable emboli filter in a collapsed state. The elongate sheath preferably has a tapered, distal region having a distally decreasing wall thickness. In one embodiment, the distally decreasing wall thickness is accomplished with a distally decreasing outside diameter. One embodiment includes a substantially sudden decrease in wail thickness at the distal region, rather than a gradual taper.
In use, the emboli filter may be collapsed, and disposed within the delivery sheath distal region. A guidewire may be advanced into the patient's vasculature and advanced further until the guidewire distal end is near the treatment site. In one method, the shaft of the emboli filter device serves as the guidewire. In another embodiment, a guidewire is first inserted, followed by the advancement of an emboli filter hollow shaft over the guidewire to a position distal of the treatment site. The emboli filter, in the collapsed state, within the delivery sheath, can be advanced together with the delivery sheath to a position near, and preferably distal of, the treatment site. The emboli filter may be advance distally out of the delivery sheath. In one method, the emboli filter is advanced distally, while the delivery sheath is held in substantially constant position. In another method, the emboli filter is held in substantially constant position, while the delivery sheath is proximally retracted.
The emboli filter, in an expanded configuration, may be left in place for the treatment process. The emboli filter may be used in conjunction with atherectomy or angioplasty procedures. After a procedure, the emboli filter may be collapsed, followed by retracting the emboli filter into the delivery sheath distal region. The emboli filter and delivery sheath may be retracted together and removed proximally from the patient's vasculature.
BRIEF DESCRIPTION OF THE DRAWINGS
Hollow guidewire 18 also preferably has a valve 30 coupled in a proximal portion thereof. During operation, a syringe is preferably connected to the proximal end of guidewire 18, which preferably includes a fluid-filled hypotube. The syringe is used to pressurize the fluid such that fluid is introduced through the lumen of hollow guidewire 18, through valve 30, and into inflatable member 28. Upon being inflated, inflatable member 28 preferably drives struts 20 to assume a deployed position in which ends 24 are pivotally or otherwise moved radially away from hollow guidewire 18 to a diameter which approximates the inner diameter of lumen 12. In this way, capturing assembly or filter 17 is deployed distally of stenosis 14 so that stenosis 14 can be severed and fragmented, and the fragments from stenosis 14 carried by blood flow, indicated by arrow 16, into the basket or chamber formed by the deployed filter 17. Filter 17 can then be collapsed and removed from vessel 12 with the fragments contained therein.
A delivery sheath 50, illustrated in phantom in
Struts 20 are preferably formed of a resilient material which has some shape memory. Thus, when inflatable member 28 is collapsed, struts 20 can also collapse to approximate the outer diameter of hollow guidewire 18. In another preferred embodiment, struts 20 are fastened to inflatable member 28 through adhesive, or another suitable connector, so that they are effectively pulled to the collapsed position shown in
In one embodiment, proximal wall thickness D1 is about 0.002 inch, distal wall thickness D2 is about 0.001 inch, and distal region length L is about 1 millimeter. In one embodiment, not requiring separate illustration, the transition from proximal wall thickness D1 to distal wall thickness D2 is a substantially sudden step decrease, rather than a gradual taper.
In one embodiment, sheath proximal region 84 has an inside diameter of 0.0200 inch and a 0.0260-inch outside diameter, being expanded at a first flared region 86 to an outside diameter of 0.0290 inch in sheath first intermediate region 82. In this embodiment, sheath second intermediate region 83 has an outside diameter of 0.0310 inch increasing to an outside diameter of 0.0395 inch in sheath distal region 74 after an increase at a second flared region 88. In one embodiment, distal portion 72 has a wall thickness of 0.0022 inches in distal region 74, decreasing to a wall thickness of 0.0011 inch in sheath reduced diameter region 78 including far distal region 76. In one embodiment, sheath first intermediate region 82 has a length of about 0.100 inch, followed by sheath second intermediate region 83 having a length of about 0.25 inch, with sheath second intermediate region 83 and sheath distal region 74 together having a length of about 15 millimeter. In one embodiment, sheath far distal region 76 has a length of about 1 millimeter.
Sheath 70 can be manufactured by forming the intermediate stage substantially as illustrated in
Numerous advantages of the invention covered by this document have been set forth in the foregoing description. It will be understood, however, that this disclosure is, in many respects, only illustrative. Changes may be made in details, particularly in matters of shape, size, and arrangement of parts without exceeding the scope of the invention. The invention's scope is, of course, defined in the language in which the appended claims are expressed.
Claims
1. A delivery sheath for an intravascular emboli capturing filter comprising: an elongate tube having a distal region, a distal end, and a lumen therethrough, wherein said distal region has a length and a distal region wall having a thickness, wherein said distal region wall thickness is distally decreasing.
Type: Application
Filed: Jul 14, 2006
Publication Date: Nov 2, 2006
Applicant: SCIMED LIFE SYSTEMS, INC. (Maple Grove, MN)
Inventors: Wayne Becker (Elk River, MN), Frank Musbach (St. Paul, MN)
Application Number: 11/457,701
International Classification: A61M 29/00 (20060101);