CUTTING BALLOON HAVING SHEATHED INCISING ELEMENTS
A cutting balloon for use in a PTCA atherectomy procedure includes an elongated balloon that defines a longitudinal axis and is inflatable from a first deflated configuration to a second radially expanded configuration. One or more incising elements are mounted on the inflatable balloon. Compressible sheaths made of a relatively low durometer, flexible material are mounted on the balloon to protect the operative cutting surface of a respective incising element during assembly of the cutting balloon and transit of the cutting balloon to the treatment site. Each sheath extends farther from the longitudinal axis than the corresponding incising element and makes first contact with the tissue during a balloon inflation. Once contact has been established between the tissue and the sheath, further balloon inflation causes the sheath to radially compress between the tissue and the inflatable balloon exposing the operative cutting surface for tissue incision.
Latest BOSTON SCIENTIFIC SCIMED, INC. Patents:
This application is a continuation of U.S. patent application Ser. No. 10/725,178, filed on Dec. 1, 2003 (pending), the entire disclosure of which is incorporated herein by reference.
FIELD OF THE INVENTIONThe present invention pertains generally to medical devices. More particularly, the present invention pertains to cutting balloon catheters for revascularization of coronary and peripheral vessels. The present invention is particularly, but not exclusively, useful as a cutting balloon having incising elements that are shielded when the balloon is deflated.
BACKGROUND OF THE INVENTIONAlthough conventional percutaneous transluminal coronary angioplasty (PTCA) procedures have been somewhat effective in treating coronary artery disease, cutting balloons are currently viewed by many as the next generation treatment option for the revascularization of both coronary and peripheral vessels. The cutting balloon mechanism is unique in that the balloon pressure is distributed over one or more incising elements (e.g. microtomes). The incising elements function as stress concentrators and cut initiators in PTCA atherectomy procedures. Consequently, PTCA atherectomy procedures have been proven to minimize vessel recoil, lessen vessel injury and lower the rate of restenosis, as compared to conventional PTCA procedures.
The incising elements used in cutting balloons include an operative surface feature (e.g. edge) that is capable of incising tissue. In the absence of suitable precautions, the incising elements can tear, cut or perforate the thin, fragile inflation balloon during assembly of the cutting balloon, handling or during clinical use. In a worst case, a balloon perforation or tear can result in an unsuccessful PTCA atherectomy procedure and the loss of inflation fluid into the patient's vasculature. In addition to balloon perforation concerns, another consideration involves the prevention of an inadvertent or unwanted cutting or incising of tissue as the cutting balloon is either being advanced into or withdrawn from the vasculature.
Along these lines, a device having a parting edge which is shielded within the pleats of an expandable clover leaf shaped tube is disclosed by Shiber in U.S. Patent Application Publication No. US 2002/0151924, filed Oct. 17, 2002 and entitled “Clover Leaf Shaped Tubular Medical Device”. However, the clover leaf design disclosed by Shiber does not necessarily protect the relatively fragile balloon during installation of the parting edges on the clover leaf balloon. In addition, because the parting edges are located within the pleats of the balloon, portions of the balloon may be exposed to the parting edges when the device is twisted, turned and bent through the curved vasculature of a patient.
In light of the above, it is an object of the present invention to provide a protective sheath for an incising element mounted on an inflatable balloon which compresses to expose the incising element during balloon inflation at a treatment site. Another object of the present invention is to provide a protective sheath for an incising element mounted on an inflatable balloon that protects the incising element from inadvertently cutting tissue as the deflated balloon is maneuvered through the vasculature of a patent. Still another object of the present invention is to provide a protective sheath for an incising element mounted on an inflatable balloon that is easy to use, relatively simple to manufacture and comparatively cost effective.
SUMMARY OF THE INVENTIONThe present invention is directed to a cutting balloon which in one application can be used on a medical catheter to incise and dilate stenotic tissue at a treatment site in a body vessel of a patient. A typical cutting balloon includes an elongated balloon that defines a longitudinal axis and is inflatable from a first deflated configuration to a second radially expanded configuration.
The cutting balloon further includes one or more rigid, elongated incising elements which could be, for example, a blade, a round wire or a hardened polymer. The incising elements are typically oriented longitudinally and mounted on the inflatable balloon. Specifically, when the inflatable balloon is in the radially expanded configuration, each incising element extends radially from the surface of the inflatable balloon to an operative surface feature (e.g. edge) that is capable of incising tissue. The cutting balloon may further include one or more mounting pads, with each mounting pad holding a respective incising element. For example, each incising element may be partially encapsulated in a respective mounting pad which, in turn, is adhesively bonded to the outer surface of the inflatable balloon.
For the present invention, the cutting balloon includes one or more compressible sheaths that are made of a relatively low durometer, flexible material. Functionally, each sheath is provided to protect the operative surface feature of a respective incising element during assembly of the cutting balloon and transit of the cutting balloon to the treatment site. In greater structural detail, each sheath may include a pair of elongated sheath members that are oriented longitudinally and attached to the mounting pad to interpose an incising element between the pair of sheath members. In one embodiment, each sheath has a single sheath member.
Each sheath member extends radially from the mounting pad and terminates at a sheath member surface that is located farther from the longitudinal axis than the operative surface feature of the corresponding incising element. With this cooperation of structure, the sheath member(s) makes first contact with the tissue during a balloon inflation. Once contact has been established between the tissue and the sheath members, further inflation of the inflatable balloon causes the sheath member(s) to radially compress, and in some cases deflect, between the tissue and the inflatable balloon exposing the operative surface feature of the incising element for tissue incision. In one aspect of the present invention, the sheath members can be configured to selectively limit the amount of incising element that is exposed, and as a consequence, control the incision depth.
The novel features of this invention, as well as the invention itself, both as to its structure and its operation, will be best understood from the accompanying drawings, taken in conjunction with the accompanying description, in which similar reference characters refer to similar parts, and in which:
Referring initially to
Referring now to
Cross-referencing
Continuing with cross-reference to
It can be further seen that each sheath member 52 extends radially from the mounting pad 46 and terminates at a surface 56 that is located farther from the longitudinal axis 33 than the cutting edge 48 of the corresponding blade 44. Specifically, as shown, each sheath member 52 extends a radial distance, ‘d’ from the outer surface 34 of the balloon 30 (when the sheath is uncompressed) and the blade 44 extends a distance ‘D’ from the outer surface 34 of the inflatable balloon 30, with ‘d’>‘D’.
For the embodiment shown in
The functionality of the sheath 50 can perhaps best be appreciated with cross-reference to
For the embodiment shown in
While the particular cutting balloon having sheathed incising elements as herein shown and disclosed in detail are fully capable of obtaining the objects and providing the advantages herein before stated, it is to be understood that they are merely illustrative of the presently preferred embodiments of the invention and that no limitations are intended to the details of construction or design herein shown other than as described in the appended claims.
Claims
1. A cutting balloon catheter for incising tissue at a treatment site in a body vessel of a patient, the cutting balloon catheter comprising:
- an elongate shaft having a proximal portion and a distal portion;
- an inflatable balloon secured to the distal portion of the elongate shaft, the inflatable balloon being inflatable from a first deflated state to a second radially expanded state;
- a cutting blade mounted on the inflatable balloon such that a cutting edge of the cutting blade is oriented radially outward from the inflatable balloon; and
- a radially compressible sheath covering the cutting edge of the cutting blade when the inflatable balloon is in the first deflated state, wherein the compressible sheath includes an engaging surface configured to contact an interior surface of the body vessel when the inflatable balloon is inflated to the second radially expanded state, the engaging surface located radially outward of the cutting edge of the cutting blade when the inflatable balloon is in the first deflated state;
- wherein the radially compressible sheath is configured to be radially compressed as the inflatable balloon is inflated to the second radially expanded state, exposing the cutting edge radially outward from the engaging surface of the radially compressible sheath.
2. The cutting balloon catheter of claim 1, wherein the engaging surface of the radially compressible sheath is a flattened surface when the inflatable balloon is in the first deflated state.
3. The cutting balloon catheter of claim 1, wherein the radially compressible sheath includes a pair of sheath members, wherein a first sheath member extends along a first side surface of the cutting blade and a second sheath member extends along a second side surface of the cutting blade.
4. The cutting balloon catheter of claim 3, wherein the first side surface of the cutting blade converges with the second side surface of the cutting blade at the cutting edge of the cutting blade.
5. The cutting balloon catheter of claim 1, wherein the radially compressible sheath encapsulates the cutting edge of the cutting blade when the inflatable balloon is in the first deflated state.
6. The cutting balloon catheter of claim 1, wherein the cutting edge has a length from a first end of the cutting edge to a second end of the cutting edge, wherein the radially compressible sheath covers the entire length of the cutting edge when the inflatable balloon is in the first deflated state.
7. The cutting balloon catheter of claim 1, further comprising a mounting pad bonded to the balloon, a base portion of the cutting blade being embedded in the mounting pad.
8. The cutting balloon catheter of claim 7, wherein the mounting pad has a length measured from a first end of the mounting pad to a second end of the mounting pad, and the radially compressible sheath has a length measured from a first end of the radially compressible sheath to a second end of the radially compressible sheath, the length of the mounting pad being greater than the length of the radially compressible sheath.
9. The cutting balloon catheter of claim 7, wherein the mounting pad has a length measured from a first end of the mounting pad to a second end of the mounting pad, and the cutting edge of the cutting blade has a length measured from a first end of the cutting edge to a second end of the cutting edge, the length of the mounting pad being greater than the length of the cutting edge of the cutting blade.
10. The cutting balloon catheter of claim 7, wherein the cutting blade includes opposing angled surfaces converging at the cutting edge, and the mounting pad contacts a portion of each of the opposing angled surfaces of the cutting blade.
11. A cutting balloon catheter for incising tissue at a treatment site in a body vessel of a patient, the cutting balloon catheter comprising:
- an elongate shaft having a proximal portion and a distal portion;
- an inflatable balloon secured to the distal portion of the elongate shaft, the inflatable balloon being inflatable from a first deflated state to a second radially expanded state;
- a mounting pad secured to the inflatable balloon;
- a cutting blade having a base portion embedded in the mounting pad such that a cutting edge of the cutting blade is oriented radially outward from the inflatable balloon; and
- a radially compressible sheath covering the cutting edge of the cutting blade when the inflatable balloon is in the first deflated state which is configured to be radially compressed as the inflatable balloon is inflated to the second radially expanded state to expose the cutting edge;
- wherein the mounting pad has a length measured from a first end of the mounting pad to a second end of the mounting pad, and the cutting edge of the cutting blade has a length measured from a first end of the cutting edge to a second end of the cutting edge, the length of the mounting pad being greater than the length of the cutting edge of the cutting blade.
12. The cutting balloon catheter of claim 11, wherein the radially compressible sheath has a length measured from a first end of the radially compressible sheath to a second end of the radially compressible sheath, the length of the mounting pad being greater than the length of the radially compressible sheath.
13. The cutting balloon catheter of claim 11, wherein the radially compressible sheath is attached to the mounting pad.
14. The cutting balloon catheter of claim 11, wherein the radially compressible sheath includes a pair of sheath members, wherein a first sheath member extends along a first side surface of the cutting blade and a second sheath member extends along a second side surface of the cutting blade.
15. The cutting balloon catheter of claim 14, wherein each of the first and second sheath members is formed as a hollow tube.
16. The cutting balloon catheter of claim 11, wherein the cutting edge of the cutting blade is encapsulated in the radially compressible sheath when the inflatable balloon is in the first deflated state.
17. The cutting balloon catheter of claim 16, wherein the cutting edge is configured to cut through the radially compressible sheath to expose the cutting edge when the inflatable balloon is inflated to the second radially expanded state.
18. The cutting balloon catheter of claim 11, wherein the radially compressible sheath is substantially rectangular shaped in a plane normal to a longitudinal axis of the cutting blade.
19. The cutting balloon catheter of claim 11, wherein the radially compressible sheath includes a flattened engaging surface when the inflatable balloon is in the first deflated state configured to contact tissue in the body vessel when the inflatable balloon is inflated to the second radially expanded state.
Type: Application
Filed: Aug 16, 2010
Publication Date: Dec 9, 2010
Applicant: BOSTON SCIENTIFIC SCIMED, INC. (Maple Grove, MN)
Inventors: Dennis O'Brien (Oceanside, CA), Carl Yee (San Diego, CA)
Application Number: 12/857,272
International Classification: A61B 17/22 (20060101);