US 20050021125 A1
A deformable sheath is attached to a catheter and introduced intravascularly to be expanded against an arterial wall and entrap plaque therebetween. A stent is subsequently deployed within the expanded sheath and the sheath is then withdrawn from within the vasculature to leave the stent expanded against the arterial wall with the plaque entrapped therebetween.
1. An assembly for trapping arterial plaque against a vascular wall, comprising:
a radially outwardly deformable, tubular sheath having a proximal end and a distal end, said sheath to be introduced intravascularly and expanded against the vascular wall to trap the plaque therebetween.
2. The assembly of
a flexible elongated tubular member with an inner lumen extending therethrough from a proximal end of the tubular member to a distal end of the tubular member that is attached to the proximal end of the sheath.
3. The assembly of
4. The assembly of
5. The assembly of
6. The assembly of
7. The assembly of
8. The assembly of
9. The assembly of
a radially outwardly deformable, tubular member disposed within the sheath between the distal end and the proximal end of the sheath to be expanded together with the sheath against the vascular wall.
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25. The assembly of
a catheter disposed within the lumen of the tubular member with a balloon portion of the catheter lying within the deformable member to expand the deformable member together with the sheath against the vascular wall.
26. The assembly of
27. The assembly of
28. The assembly of
29. A method for entrapping plaque particles against a vascular wall at a predetermined intravascular site, comprising the steps of:
providing a radially outwardly deformable, tubular sheath having a proximal end and a distal end;
providing an intravascular deployment catheter having a proximal end, a distal end, and a lumen extending therebetween;
attaching the sheath proximal end to the deployment catheter distal end;
introducing the deployment catheter into the vasculature;
advancing the deployment catheter through the vasculature to position the sheath at the intravascular site; and
expanding the sheath against the vascular wall at the intravascular site to trap the plaque therebetween.
30. The method of
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32. The method of
33. The device of
34. The method of
35. The method of
providing a radially outwardly deformable, tubular member;
disposing the deformable member within the sheath; and wherein the step of expanding the sheath comprises expanding the deformable member along with the sheath, the sheath contacting the vascular wall and the deformable member contacting the sheath.
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providing a delivery catheter having a proximal end and a distal end and a lumen extending therebetween;
providing a self-expanding intravascular device having a proximal end and a distal end and further having a compressed state and an expanded state;
placing the intravascular device in its compressed state within the delivery catheter distal end;
introducing the delivery catheter into the lumen of the deployment catheter;
advancing the delivery catheter through the lumen of the deployment catheter to position the distal end of the delivery catheter adjacent the distal end ofthe sheath;
partially retracting the delivery catheter to allow the distal end of the intravascular device to expand against the vessel wall at a location distal of the plaque at the intravascular site;
withdrawing the sheath proximally from the intravascular site to expose the distal end of the delivery catheter;
retracting the delivery catheter to allow the entire intravascular device to expand against the vessel wall at the intravascular site and trap the plaque therebetween;
withdrawing the delivery catheter from within the intravascular catheter; and
withdrawing the intravascular catheter and the sheath from within the vasculature.
47. The method of
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52. The method of
the step of expanding the sheath against the vascular wall comprises partially expanding the sheath; and comprising, after the step of withdrawing the delivery catheter, the further steps of: providing a balloon catheter; inserting the balloon catheter into the lumen of the deployment catheter;
advancing the balloon catheter to position the balloon within the intravascular device;
inflating the stent to further expand the intravascular device against the vessel all and entrap the plaque therebetween; and
withdrawing the balloon catheter from the deployment catheter lumen.
53. The method of
54. An assembly for trapping arterial plaque against a vascular wall, comprising:
a deployment catheter having a proximal end, a distal end, and an inner lumen extending therebetween;
a radially outwardly, deformable, tubular sheath to be introduced intravascularly and expanded against the vascular wall to entrap the plaque therebetween, the sheath having a proximal end attached to the deployment catheter distal end, and a distal end;
a delivery catheter being axially movably disposed within the deployment catheter lumen and having a distal end and an inner lumen;
a self-expanding intravascular device disposed within the delivery catheter lumen adjacent the delivery catheter distal end;
an outer sheath disposed over the deployment catheter to receive the deformable sheath therein; and
a pusher rod axially movably disposed within the delivery catheter lumen proximal of the intravascular device.
55. The assembly of
an outer sheath disposed over the tubular member to receive the sheath therein.
1. Field of the Invention
The present invention relates to angioplasty procedures, and more particularly to a device and method to prevent arterial plaque from being dislodged from the arterial wall in procedures such as, for example, percutaneous transluminal coronary angioplasty (PTCA) or percutaneous transluminal angioplasty (PTA), especially carotid PTA, and migrating into the patient's vasculature.
In typical carotid PTA procedures, a guiding catheter or sheath is percutaneously introduced into the cardiovascular system of a patient through the femoral arteries and advanced through the vasculature until the distal end of the guiding catheter is in the common carotid artery. A guidewire and a dilatation catheter having a balloon on the distal end are introduced through the guiding catheter with the guidewire sliding within the dilatation catheter. The guidewire is first advanced out of the guiding catheter into the patient's carotid vasculature and is directed across the arterial lesion. The dilatation catheter is subsequently advanced over the previously advanced guidewire until the dilatation balloon is properly positioned across the arterial lesion. Once in position across the lesion, the expandable balloon is inflated to a predetermined size with a radiopaque liquid at relatively high pressures to radially compress the atherosclerotic plaque of the lesion against the inside of the artery wall and thereby dilate the lumen of the artery. The balloon is then deflated to a small profile so that the dilatation catheter can be withdrawn from the patient's vasculature and the blood flow resumed through the dilated artery. As should be appreciated by those skilled in the art, while the above-described procedure is typical, it is not the only method used in angioplasty.
In angioplasty procedures of the kind referenced above, abrupt reclosure may occur or restenosis of the artery may develop over time, which may require another angioplasty procedure, a surgical bypass operation, or some other method of repairing or strengthening the area. To reduce the likelihood of the occurrence of abrupt reclosure and to strengthen the area, a physician can implant an intravascular prosthesis for maintaining vascular patency, commonly known as a stent, inside the artery across the lesion. The stent is crimped tightly onto the balloon portion of the catheter and transported in its delivery diameter through the patient's vasculature. At the deployment site, the stent is expanded to a larger diameter, often by inflating the balloon portion of the catheter. The stent also may be of the self-expanding type.
A danger always present during any intravascular procedure is the potential for particles of the atherosclerotic plaque, which can be extremely friable, breaking away from the arterial wall. These emboli can subsequently migrate through the patient's vasculature to sensitive organs such as the brain, where they may induce trauma.
2. Description of the Prior Art
The majority of devices that have been proposed to prevent the problem of emboli generated during an angioplasty procedure fall into either of two broad categories: devices that simply intercept emboli flowing within the patient's blood stream, and devices that intercept as well as remove such emboli from within the patient's body. A device typical of the first category is described by Goldberg in U.S. Pat. No. 5,152,777 and consists of a filter comprised of a plurality of resilient, stainless steel wire arms joined at one end so as to form a conical surface, and having rounded tips at their other ends to prevent damage to the vessel walls. Alternatively, the filter may be attached to a catheter through which lysing agents can be introduced to dissolve any trapped emboli. Most devices of this type are intended for permanent deployment within the patient's body, and thus pose the risk of trapping sufficient emboli to adversely affect the flow of blood within the vessel in which they are deployed. Furthermore, any foreign object in the body tends to provoke a response from the immune system and over time can lead to endothelial cell formation.
Devices that remove emboli from the blood stream are similar to the filter devices described above and are typically connected to a deployment device such as a catheter that permits their withdrawal from the vasculature. U.S. Pat. No. 4,969,891 to Gewertz, for example, discloses a removable vascular filter permanently attached to a wire sufficiently long to extend out of the patient when the filter is deployed within. The filter is comprised of a bundle of wires secured together and having end portions that flare outwards to form the actual filter element. The filter is introduced through a catheter and the filter wires expand on their own once released from the catheter to obstruct the vessel and strain the blood flowing therethrough. This device, and others like it, are not adapted for permanent deployment within the body and can only be used for limited periods of time, limiting their efficacy.
In light of the above, it becomes apparent that there remains a need for a device or method that will prevent friable plaque from breaking away from arterial walls during intravascular procedures and forming emboli in the bloodstream, that is easy and safe to deploy, and that may be easily removed or alternatively employed over extended periods of time with minimal adverse impact or immunological response.
The present invention addresses the above mentioned need by providing a sheath at the distal tip of a catheter to be expanded against an arterial wall and trap plaque therebetween. A stent or other intravascular graft subsequently can be partially deployed distally of the plaque, the sheath then can be removed, and the stent fully expanded to trap the arterial plaque and any emboli between the stent and the arterial wall.
Thus, in one aspect, it is an object of the present invention to provide a device for trapping plaque against a vascular wall comprising an expandable sheath mounted to the distal end of an elongated tube such as a catheter, the sheath to be expanded by a balloon against a mass of atherosclerotic plaque site lining the intima of a body vessel. In another aspect of the present invention, the expandable sheath is reinforced by an expandable element embedded within it.
In yet another aspect of the present invention, an assembly is provided for trapping plaque against a vascular wall comprising an expandable sheath mounted to the distal end of an elongated tube such as a perfusion catheter, a delivery catheter axially slidably disposed within the perfusion catheter, a self-expanding intravascular device such as a stent disposed within the distal tip of the delivery catheter, and a pusher rod axially slidably disposed within the delivery catheter.
It is a further object of the present invention to provide a method for trapping plaque against a vascular wall comprising the steps of expanding a sheath mounted to the distal end of an elongated tube such as a perfusion catheter against the plaque, inserting within the perfusion catheter a delivery catheter with a self-expanding intravascular device such as a stent or intravascular graft disposed within its distal end and a pusher rod disposed adjacent the intravascular device, positioning the delivery catheter distal tip within the expanded sheath, partially withdrawing the delivery catheter to allow the distal portion of the intravascular device to expand against the vessel wall at a location distal of the plaque, withdrawing the expanded sheath, and withdrawing the delivery catheter to expose the rest of the intravascular device and thus allow it to fully expand and trap the plaque against the vessel wall.
With reference to
With continued reference to
In a preferred embodiment, catheter 130 is a perfusion catheter provided with perfusion holes 138 formed near distal end 134. Perfusion holes 138 extend from the outside of catheter 130 through catheter wall 131 to inner lumen 132 to allow blood or any other fluid flowing through body lumen 110 to pass between the outside of the catheter and the inner lumen. This feature allows the sheath of the present invention and its associated delivery device to be deployed within a patient's vasculature for extended periods of time without blocking the patient's blood flow. In a preferred embodiment, blood flow through the perfusion holes will be somewhat less than normal blood flow which will lessen the chance of dislodging particles, and if particles are dislodged, the emboli will move more slowly in the reduced blood flow and will be easier to trap in sheath 100.
Sheath 100 is formed from a permanently deformable material, preferably a polymeric material such as a low or medium molecular weight polyolefin, examples of which include PE, EVAc, EVA, and Ionomers. Any other plastically deformable material or blend of materials, including cross-linked materials and composites, may be suitable. The material, once formed into sheath 100, should preferably display a plastic yield strength of between 50 psi and 300 psi, and a tensile break strength of over 2,000 psi. The catheter is of conventional construction with an inner diameter of preferably no less than 8 French in size. Sheath 100 may be attached to distal end 134 of catheter 130 by any known means, such as adhesives or thermoplastics, or may be formed integrally as one piece with the catheter wall 131 through any known extrusion, drawing, rolling, or similar process.
With reference now to
In keeping with the invention, as shown in
Once perfusion catheter 130 has been properly positioned with sheath 100 adjacent to arterial plaque 114, guidewire 200 may optionally be withdrawn. Conventional balloon catheter 210 next is inserted within inner lumen 132 of perfusion catheter 130 and advanced over guidewire 200 until balloon 212 on the distal end of the balloon catheter is positioned within sheath 100 with the distal end of the balloon extending past the distal end of the sheath. It is understood that the type of balloon catheter that is employed is dictated by whether guidewire 200 remains within perfusion catheter 130 throughout the procedure or is withdrawn following placement of perfusion catheter 130 and sheath 100. Balloon catheter 210 will typically also have a radiopaque marker 214 to aid the physician in accurately placing balloon 212. Optionally, balloon catheter 210 may also be a perfusion catheter with perfusion holes 218 provided distally and proximally of the balloon 212, which allow uninterrupted blood flow to the brain throughout the entire procedure.
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Self-expanding stent 320 can be formed from any number of materials, including metals, metal alloys, and polymeric materials. Preferably, the stents are formed from metal alloys such as stainless steel, tantalum, or the so-called heat-sensitive metal alloys such as nickel titanium (NiTi). When formed from shape-memory alloys such as NiTi, stent 320 will remain passive in its martensitic state when it is kept at a temperature below the transition temperature. In this case, the transition temperature will be below the normal body temperature, or about 98.6° F., and in a preferred embodiment the stent self expands at room temperature. When the NiTi is exposed to normal body temperature upon insertion of delivery catheter 310 into perfusion catheter 130, it will attempt to return to its austenitic state and, if not constrained, will rapidly expand radially outwardly to assume its preformed, expanded state. Alternative shape-memory materials that may be used to form stent 320 include stress-induced martensite (SIM) alloys, which transform into martensite upon the application of stress such as a compressive load, and return to their austenitic, preformed state when the stress is removed.
Stent 320 is thus restrained by delivery catheter 310 from assuming its expanded state, and the delivery catheter wall must be of sufficient thickness to withstand the radially outward expansive forces exerted by the stent upon it. Delivery catheter 310 typically is provided with radiopaque marker 314 to aid the physician in accurately positioning its distal tip relative to sheath 100. The radiopacity of stent 320 also further enhances the visualization of delivery catheter 310 via fluoroscopy. With continued reference to
Referring now to
With continued reference to
To be able to intercept and retain plaque that may break off, the stent must be designed such that, when in its expanded state, the apertures in the stent wall are no larger than about 200 microns, more preferably no larger than about 50 to 100 microns, and in a preferred embodiment no larger than 25 microns. Thus, the stent may be an expandable tube with slots or other shaped apertures cut therein, or a wire mesh, or a wire coil, or any other practicable self-expanding device. Co-owned U.S. Pat. No. 5,514,154 to Lau et al., U.S. Pat. No. 5,569,295 to Lam, U.S. Pat. No. 5,591,197 to Orth et al., U.S. Pat. No. 5,603,721 to Lau et al., U.S. Pat. No. 5,649,952 to Lam, U.S. Pat. No. 5,728,158 to Lau et al., and U.S. Pat. No. 5,735,893 to Lau et al. describe suitable stents, and these patents are hereby incorporated herein in their entirety by reference thereto. The device of the present invention may also be used in conjunction with other expandable intravascular devices, such as grafts or fine mesh filters that may have a completely or substantially closed outer surface.
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In an alternative embodiment of the device of the present invention, as depicted in
With continued reference to
In view of the foregoing, it is apparent that the device and method of the present invention enhance substantially the safety of angioplasty procedures by significantly reducing the risk associated with friable plaque deposits breaking away from the vascular wall and migrating into the patient's blood stream to form emboli and potentially cause injury. Further modifications and improvements may additionally be made to the device and method disclosed herein without departing from the scope of the invention. Accordingly, it is not intended that the invention be limited, except as by the appended claims.