Patent Application
20080015675
The features and advantages of the present invention are well understood by reading the following detailed description in conjunction with the drawings in which like numerals indicate similar elements and in which:
An advanceable, non-removable guide wire balloon catheter delivery system 21 for a stent 23 is shown in
The system 21 also includes a guidewire 37 disposed in and having a limited range of longitudinal movement relative to the inner tubular element 33. The guidewire 37 can be rotated relative to the inner tubular element 33. The longitudinal movability and rotatability of the guidewire 37 relative to the inner tubular element 33 facilitates accessing tight lesions and maneuvering curves or branches in a patient's vasculature. In the system 21 according to present invention, the guidewire 37 is longitudinally movable relative to the inner tubular element 33, ordinarily up to about 15 cm, although the guidewire may be movable relative to the inner tubular element over a greater or lesser distance. Typically, however, the guidewire 37 will be longitudinally movable relative to the inner tubular element 33 between about 3 cm and about 10 cm. The guidewire 37 is movable relative to the catheter 25, but is not removable. A tip 39 is typically secured to a distal part of the guidewire 37, the tip having a larger diameter than the guidewire, and is too large to be drawn through the distal end of the inner tubular element 33, thus preventing removal of the guidewire from the catheter 25. The tip 39 can be in any suitable form, such as in the form of a coil to which a semi-spherical tip is secured as disclosed in U.S. Pat. No. 4,616,653.
An expandable stent 23 is mounted on the balloon 27. The stent 23 may be a drug-eluting stent. A non-coated, drug eluting stent of the type described in WO 03/015664, which is incorporated by reference, which has drug inlays in reservoirs within the stent, is anticipated to be particularly well-suited for use in connection with the present invention because there is no coating which can be damaged or scraped off while passing the stent through small openings such as tight lesions. Other types of uncoated stents that are likely to be well-suited for use in connection with the present invention include bioresorbable drug impregnated stents and stents in which drugs are provided in channels or grooves in the stents.
It is possible to construct the system 21 in a manner that minimizes the crossing profile or delivery diameter of the stent 23 mounted on the balloon 27. For example, a distal part 47 of the guidewire 37 can be provided with at least a portion having a narrower diameter than a proximal part 49. The inner tubular element 33 and the outer tubular element 35 around the narrowed portion of the distal part 47 of the guidewire 37 can have a reduced diameter relative to portions of the inner tubular element and the outer tubular element (or catheter shaft 65 attached to outer tubular element) around larger diameter portions of the guidewire 37. As a consequence, the expandable stent 23 can have a reduced crossing profile or delivery diameter relative to systems such as those wherein a stent is implanted via a balloon catheter that is moved along a constant diameter guidewire such as over-the-wire catheterization or rapid catheter exchange. This can facilitate use of a stent in circumstances where blood vessels or lesions are too constricted to permit a stent to be implanted by conventional techniques without predilation.
Largely because of the ability of the advanceable, non-removable guide wire balloon catheter delivery system 21 for a stent 23 to have a minimal crossing profile or delivery diameter, it can be of particular use in connection with direct stenting procedures in which a stent is implanted in a patient without predilation with an angioplasty balloon. In a direct stenting procedure, the balloon 27 and stent 23 together pass through a constricted portion of a blood vessel or lesion site. When the stent 23 is positioned as desired, the balloon 27 is inflated, expanding the stent. The balloon 27 can then be deflated and the catheter system 21 can be withdrawn together with the guidewire 37, leaving the expanded stent 23 in place.
Thus, a direct stenting procedure with an advanceable, non-removable guide wire balloon catheter delivery system 21 for a stent 23 can be faster, or at least involve fewer steps, than a stenting procedure that requires, e.g., introducing, over a guidewire, a balloon catheter to the blood vessel for predilation of the blood vessel followed by removal of the balloon catheter and introduction of a stent over the same guidewire. A non-coated, drug eluting stent 23 of the type having the drug within the stent is of particular use in connection with a direct stenting procedure using the advanceable, non-removable guide wire balloon catheter delivery system 21 for a stent because a coating on the stent is not apt to be damaged or scraped off while passing the stent through small openings such as tight lesions.
In direct stenting operations, it is generally desirable to use balloons with high rated burst pressures (RBP). Typical RBPs for known balloons is about 16-18 atmospheres. The higher a balloon's rated burst pressure, the more it is likely to be able to fully expand a stent in an undilated lesion. This is important, of course, because, if the stent does not fully expand, it may be difficult to remove the balloon and it may have to be surgically removed. Also, even if the balloon can be removed when a stent has not been fully expanded, it will still be necessary to get another balloon into the stent to expand it, which can be very difficult.
Typical RBPs for known balloons is about 16-18 atmospheres. According to aspects of the present invention, the RBP of a balloon can be higher than typical RBPs while having the same or a reduced crossing profile or diameter as the known balloons at least because, according to aspects of the present invention, the reduced diameter portion 53 of the inner tubular element 31 and the reduced diameter portion 47 of the guidewire 37 permit use of an outer tubular element 35 having thicker walls than is typical, while still maintaining a small crossing profile or delivery diameter. Thicker walls in the outer tubular element can facilitate operation of balloon catheter delivery systems according to aspects of the present invention with balloons having higher RBPs, i.e., RBPs above those of typical balloon catheters, such as RBPs in the range of greater than 18 and, using presently available materials, likely up to RBPs of about 20 atmospheres or more. The higher a balloon's rated burst pressure, the more it is likely to be able to fully expand a stent in an undilated lesion. This is important, of course, because, if the stent does not fully expand, it may be difficult to remove the balloon and it may have to be surgically removed. Also, even if the balloon can be removed when a stent has not been fully expanded, it will still be necessary to get another balloon into the stent to expand it, which can be very difficult.
The advanceable, non-removable guide wire balloon catheter delivery system 21 for a stent 23 comprises what shall be denominated an insertion stop for limiting relative longitudinal forward movement of the guidewire 37 inside the inner tubular element 33. An embodiment of an insertion stop is seen in
Another form of stop that can be provided with the balloon catheter delivery system 21 prevents relative longitudinal rearward movement, i.e., retraction, of the guidewire 37 beyond a particular position relative to the balloon 27 and is herein denominated a retraction stop. In an embodiment, such a stop is provided where the proximal end of an enlarged portion of the guidewire 37, such as a proximal end of the tip 39, comes into contact with the distal ends 29 and 31 of the inner and outer tubular elements 33 and 35 or another tip of the catheter.
When the guidewire transition 45 contacts the inner tubular element transition 51, the guidewire 37 may be in its forwardmost position relative to the inner tubular element 33. As seen in
As seen in
As seen in
It is desirable that the advanceable, non-removable guide wire balloon catheter delivery system 21 be capable of being pushed through small openings. U.S. patent application Ser. No. 11/251,236, filed Oct. 13, 2005, entitled RAPID EXCHANGE CATHETER WITH HYPOTUBE AND SHORT EXCHANGE LENGTH is incorporated by reference and discloses catheter systems using laser-cut hypotubes due to their excellent pushability and small diameter. The advanceable, non-removable guide wire balloon catheter delivery system 21 can include a catheter shaft 65 as seen in
In a method according to an aspect of the present invention, a direct stenting method of implanting a stent 23 in a patient is provided. According to the method, an advanceable, non-removable guide wire balloon catheter delivery system 21 for a stent 23 is provided, the system comprising a balloon dilation catheter 25 comprising a balloon 27 defined by at least parts of distal parts 29 and 31 of an inner tubular element 33 and an outer tubular element 35. The system 21 further comprises a guidewire 37 disposed in and having a limited range of longitudinal movement relative to the inner tubular element 33 and a full range of rotational movement. The system 21 further comprises an expandable stent 23 mounted on the balloon 27. The stent 23 mounted on the balloon 27 in a deflated condition (
Without intending to limit the present invention to components having any specific dimensions, following are typical dimensions for components for use in connection with embodiments of the present invention. A stent 23 for use in connection with the present invention is typically 8-40 mm (0.31-1.57 inches) in length and has an unexpanded diameter of 1.01 mm (0.040 inches) or less, and preferably 0.094 mm (0.037 inches) or less, when fully crimped. The stent 23 typically has an expanded diameter of 2-5 mm (0.08-0.20 inches) when fully expanded by the balloon. The balloon portion 35a of the outer tubular member 35 is typically about 1-2 mm (0.04-0.08 inches) longer than the stent 23 and has a diameter of 0.63-1.0 mm (0.025-0.040 inches) when uninflated and a diameter sufficient to fully deploy the stent when inflated. The balloon portion 35a typically has a wall thickness of approximately 0.01-0.03 mm (0.0005-0.0013 inches) when deflated, although the balloon will often be folded, such as in a tri-fold, quad-fold, or more folds, for delivery, which can add to delivery diameter.
The proximal balloon leg 35c typically has an outside diameter of 0.64-0.90 mm (0.025-0.035 inches) and a wall thickness of about 0.06-0.25 mm (0.002-0.010 inches). The distal part of the catheter shaft 65 proximate the proximal balloon leg 35c can have an outside diameter of 0.066-1.02 mm (0.026-0.40 inches) where it transitions to the proximal balloon leg. This distal part of the catheter shaft 65 may step down in diameter as shown in
The narrow diameter portion 53 of the inner tubular element 33 can have an outside diameter of 0.03-0.58 mm (0.012-0.023 inches and a wall thickness of 0.05-0.13 mm (0.002-0.005 inches), and the larger diameter portion 55 of the inner tubular element can have an outer diameter of 0.51-0.76 mm (0.020-0.030 inches) (or about 1.5 to 2 times the diameter of the narrow diameter portion) and a wall thickness of 0.05-0.18 mm (0.002-0.007 inches). A length of the transition portion 51 of the inner tubular element 33 is typically between 0.01-3 cm (0.004-1.18 inches). The transition portion 51 of the inner tubular element 33 is typically located 1-5 cm (0.4-2 inches) from the proximal balloon leg 35c. The transition portion 51 of the inner tubular element 33 can be proximal of or at any transition 65a in the catheter shaft 65 hypotube 67. The transition portion 51 of the inner tubular element 33 is typically located within 0-5 cm (0-2 inches) of the proximal balloon leg 35c.
The transition from a large diameter portion 49 of the guidewire 37 to the narrower diameter portion 47 of the guidewire will ordinarily depend upon an amount of travel desired, although it is anticipated that it will ordinarily be between 2-15 cm (0.79-5.90 inches) behind the distal part of the guidewire, i.e., behind the tip 39. The large diameter portion 49 of the guidewire 37 typically has a diameter of about 0.35-0.45 mm (0.014-0.018 inches) and the narrow diameter portion 47 typically is about 0.15-0.254 mm (0.006-0.010 inches). The narrow diameter portion 47 generally has a diameter that is no greater than 70% of the diameter of the large diameter portion 49, and more typically no greater than 60% of the diameter of the larger diameter portion.
A balloon catheter system 121 that can comprise a balloon dilation catheter delivery system 21 for a stent 23 as has been described, or some other balloon dilation catheter system, is seen in
The balloon catheter system 121 also includes a sheath 123 having a proximal end 125 that is removably attachable to a distal end 127 of the adapter 52. The sheath 123 is adapted to be disposed around at least part of the catheter and, ordinarily, when the sheath is attached to the distal end 127 of the adapter 52, the balloon 27 will extend out of a distal end 129 of the sheath. In the illustrated embodiment, a guidewire 37 is disposed in and has a limited range of longitudinal movement relative to the inner tubular element 33 and, ordinarily, when the sheath is attached to the distal end 127 of the adapter 52, the tip 39 of the guidewire 37 will extend out of a distal end 129 of the sheath.
The balloon catheter system 121 can also comprise a sheath taper 137 that corresponds to a taper 65a in the catheter. In the embodiment of
Longitudinal movement of the catheter relative to the sheath 123 is ordinarily limited by the tapers 65a and 137 such that the distal end of the balloon 27 is adapted to extend no further than about 20 cm (7.87 inches), preferably 10 cm (3.94 inches), past the distal end 129 of the sheath, and the distal end or tip 39 of the guidewire 37 is adapted to extend no further than about 15 cm (5.91 inches) past the distal end of the balloon, and no further than about 35 cm (13.78 inches) past the distal end of the sheath.
The balloon catheter system 121 can comprise a lock 139 for removably attaching the proximal end 125 of the sheath 123 to the distal end 127 of the adapter 52. The lock 139 can take any suitable form and will ordinarily be adapted to at least prevent relative axial movement of the sheath 123 and the adapter 52. The lock 139 will also ordinarily be adapted to prevent relative rotational movement of the sheath 123 and the adapter 52. While various locking arrangements are known and are suitable for use as the lock 139, as seen in
The balloon catheter system 121 facilitates performing a catheterization method as seen in
A disadvantage of fixed wire balloon catheter or semi-movable wire balloon catheters is that, in circumstances where it is desirable to remove the balloon catheter and insert another catheter or device to the treatment site, there is no guidewire remaining behind for quick access to the treatment site. For example, when a stent is not completely deployed or a dissection occurs, it may be desirable to remove the stent delivery catheter and insert another longer or larger balloon catheter to post dilate the site. In another case, if it is determined that a stent is the improper size, it may be desirable to remove and replace the catheter and stent with a correct size before deployment of the stent. Also, if a stent is implanted and determined to be not correctly placed or not long enough, an additional procedure may be desired to add an additional stent, called an overlap. In another example, where, after a first stent placement, it is determined that another procedure is needed at a location distal of the first stent, it may be desirable to remove the first catheter and insert a second catheter and/or stent. In each of these cases, and in other similar situations, the sheath 123 of the invention provides an alternative for reaccessing a site with a second catheter in an expeditious manner. The proximal end 125 of the sheath 123 can then be detached from the distal end 127 of the adapter, and the sheath can be advanced over the balloon at the further location. Such a method might be desirable, for example, when an area of dissection in a blood vessel is disposed forward of a location to which a stent is to be delivered.
After advancing the sheath 123 over the balloon 27, the catheter can be withdrawn from the sheath while leaving the sheath in place, i.e., at or beyond the further location to which the balloon had been advanced and at which it had been expanded. As seen in
In the present application, the use of terms such as “including” is open-ended and is intended to have the same meaning as terms such as “comprising” and not preclude the presence of other structure, material, or acts. Similarly, though the use of terms such as “can” or “may” is intended to be open-ended and to reflect that structure, material, or acts are not necessary, the failure to use such terms is not intended to reflect that structure, material, or acts are essential. To the extent that structure, material, or acts are presently considered to be essential, they are identified as such.
While this invention has been illustrated and described in accordance with a preferred embodiment, it is recognized that variations and changes may be made therein without departing from the invention as set forth in the claims.
