Angioplasty cutting device and method for treating a stenotic lesion in a body vessel

An integrally formed angioplasty cutting device for balloon angioplasty of a stenotic lesion in a body vessel. The device comprises a distal collar and a proximal collar. The device further comprises at least one strut integrally formed with the distal collar and the proximal collar. At least one of the collars has a slot formed therethrough defining a C-shaped configuration. The strut is configured to be disposed at the stenotic lesion to engage the stenotic lesion for dilatation of the body vessel during angioplasty.

BACKGROUND OF THE INVENTION

The present invention relates to medical devices. More particularly, the present invention relates to angioplasty cutting devices and methods for treating a stenotic lesion in a body vessel.

Vascular diseases, such as coronary artery disease, are common diseases. Such diseases are caused by stenotic lesions narrowing in a body vessel within the vasculature. Generally, carotid artery stenosis is the narrowing of the carotid arteries, the main arteries in the neck that supply blood to the brain. Carotid artery stenosis (also called carotid artery disease) is a relatively high risk factor for ischemic stroke. The narrowing is usually caused by plaque build-up in the carotid artery. Plaque forms when cholesterol, fat and other substances form in the inner lining of an artery. This formation is called atherosclerosis.

Currently, depending on the degree of stenosis and the patient's overall condition, carotid artery stenosis can usually be treated with surgery. The procedure is (with its inherent risks) called carotid endarterectomy, which removes the plaque from the arterial walls. Carotid endarterectomy has proved to benefit patients with arteries stenosed by about 70% or more. For people with arteries narrowed less than 50%, an anti-clotting agent may be prescribed to reduce the risk of ischemic stroke.

Carotid angioplasty is another treatment for carotid artery stenosis. This treatment uses balloons and/or stents to open a narrowed artery. Carotid angioplasty is a procedure that can be performed via a standard percutaneous transfemoral approach with the patient anesthetized using light intravenous sedation. At the stenosis area, an angioplasty balloon is delivered to predilate the stenosis in preparation for stent placement. The balloon is then removed and exchanged via catheter for a stent delivery device. Once in position, a stent is deployed across the stenotic area. If needed, an additional balloon can be placed inside the deployed stent for post-dilation to make sure the struts of the stent are pressed firmly against the inner surface of the vessel wall.

However, an ongoing problem with angioplasty is that the arterial blockage may return, usually within about 6 months. It is thought that the mechanism of this phenomenon, called “restenosis,” is not the progression of the arterial disease, but rather the body's immune system response to the angioplasty. At this point, a repeat procedure may need to be performed.

Thus, there is a need to provide a way for decreasing the likelihood of restenosis without the inherent risks of surgery.

BRIEF SUMMARY OF THE INVENTION

The present invention generally provides an improved cutting assembly, an integrally formed cutting device, and an improved method for treating a stenotic lesion of a body vessel, decreasing the likelihood of restenosis without the inherent risks of surgery. Embodiments of the present invention provide a simple, efficient and cost effective device and a way of treating atherosclerosis and stenosis of a body vessel. For example, the integrally formed cutting device of the present invention provides an effective, efficient way of breaking plaque of a stenotic lesion while having the capability of using various sizes of angioplasty balloons.

One embodiment of the present invention is an integral angioplasty cutting device for balloon angioplasty of a stenotic lesion in a body vessel. The device is an integral member and comprises a distal collar configured to be disposed at the distal end of the stenotic lesion relative to the device. The device further comprises at least one strut integral with the distal collar and proximally extending therefrom. The at least one strut is configured to be disposed at the stenotic lesion to engage the stenotic lesion for dilatation of the body vessel during angioplasty. The device further comprises a proximal collar configured to be disposed at the proximal end of the stenotic lesion relative to the device. The at least one strut is integral with the proximal collar. In this embodiment, the at least one of the distal collar and proximal collar has a slot formed therethrough to define a C-shaped configuration. The C-shaped configuration allows the device to be coaxially adaptable about an expandable balloon for angioplasty. The C-shaped configuration of one of the collar allows the device to be fastened on the expandable balloon, thereby minimizing the cross-sectional profile of the device.

Yet another embodiment of the present invention is an atherosclerosis cutting apparatus for treatment of a stenotic lesion in a body vessel. The apparatus comprises a balloon catheter having a tubular body and an expandable balloon attached to and in fluid communication with the tubular body for angioplasty at the stenotic lesion. The expandable balloon has distal and proximal portions. The apparatus further includes the integral angioplasty cutting device coaxially adaptable about the expandable balloon for angioplasty of the stenotic lesion in the body vessel.

In another example, the present invention provides a method for treatment of a stenotic lesion in a body vessel. The method comprises percutaneously introducing an expandable balloon at a stenotic lesion in a body vessel and disposing the integral atherosclerosis cutting device coaxially about the expandable balloon for angioplasty of the stenotic lesion in the body vessel. The method further includes fracturing the stenotic lesion in the body vessel on each radial plane of fracture by expanding the balloon and the device on the stenotic lesion.

Further objects, features, and advantages of the present invention will become apparent from consideration of the following description and the appended claims when taken in connection with the accompanying drawings.

DETAILED DESCRIPTION OF THE INVENTION

The present invention generally provides an improved cutting assembly, an integrally formed cutting device, and an improved method for treating a stenotic lesion of a body vessel. Embodiments of the present invention provide a more simple, efficient and cost effective way of treating atherosclerosis and stenosis of a body vessel. For example, the integrally formed cutting device includes distal and proximal collars having a C-shaped configuration and being integrated with a cutting body extending integrally therebetween. The device is configured to be disposed about one of a number of various-sized expandable balloons of a balloon catheter for angioplasty. The cutting body has one or a plurality of struts which expand as the expandable balloon is inflated. Each strut defines a focal point or a radial plane of fracture on the stenotic lesion whereat lacerations on the stenotic lesion are formed. Upon contact with the stenotic lesion, the struts break the plaque in a relatively organized fashion, lessening the likelihood of restenosis of the body vessel.

FIG. 1illustrates an angioplasty cutting assembly or apparatus10having an expandable balloon16and implementing an integrally formed atherosclerosis cutting device12in accordance with one embodiment of the present invention. As depicted inFIGS. 1 and 2, the cutting assembly10includes a balloon catheter14about which the device12is disposed. As shown, the balloon catheter14comprises an expandable balloon16for angioplasty treatment of a stenotic lesion18of a body vessel19. The balloon catheter14is configured to be cooperable with the device12during the procedure. As shown, the device12is disposable about the expandable balloon16of the assembly10. As the balloon is inflated, the device12expands to engage the stenotic lesion18of the body vessel19.

FIG. 1further depicts the assembly10in a collapsed or an unexpanded state that the device12takes on during delivery and retrieval thereof.FIG. 2shows the assembly10in an expanded state that the device12takes on during angioplasty. The expandable balloon16of the assembly10may be inflated and deflated by any suitable means, e.g., by introducing saline into the expandable balloon16as known in the art.

FIGS. 1-3bgenerally illustrate the device12in this embodiment being a one-piece member or an integral device. As shown, the device12comprises a distal collar20, a cutting body22integrally extending from the distal collar20, and a proximal collar24to which the cutting body22integrally extends.FIGS. 3aand3bdepict the distal collar20having a tapered, atraumatic distal tip23for enhanced guidance and reduced trauma in the body vessel of a patient. For enhanced atraumatic performance, the distal tip23may be coated with soft, hydrophilic material such as low density polyethylene, polypropylene, polytetrafluoroethylene (PTFE) or any other suitable material or mixtures thereof.

Preferably, at least one of the distal collar20and the proximal collar24of the cutting device12has a slit or slot formed therethrough defining a C-shaped configuration of the device12. As shown, the C-shaped configuration is formed longitudinally relative to the device12, defining an opening27. The C-shaped configuration is formed longitudinally relative to the device, allowing the collar to be fastened about the expandable balloon for attachment to the assembly. In this embodiment, the openings27may have a size of between about 0.01 mm (about 0.0004 in) and 1 mm (about 0.04 in). Each of the openings27allows its respective collar20or24to be attached or fastened about the balloon catheter or expandable balloon for attachment to the assembly10. Preferably, both of the distal and proximal collars20,24include the C-shaped configuration. The C-shaped configuration formed on each or both of the collars20,24further allows device12to be manufactured at a reduced cross-sectional profile. In turn, this reduces cross-sectional profile of the balloon catheter and expandable balloon, thereby lowering the overall minimum cross-sectional profile of the assembly.

The cutting body22defines at least one radial plane of fracture A (seeFIG. 4) in the body vessel19during angioplasty. As shown, the distal collar20is preferably ring or collar shaped and located at the distal portion of the cutting device12. In this embodiment, the distal collar20is configured to be disposed about and adjacent the distal end21of the expandable balloon16relative to the device12.

As will be discussed in greater detail below, the device of this embodiment is an integral member formed from a single solid tube of any suitable material discussed below. Known manufacturing techniques may be implemented to form the distal collar, the cutting body, and the proximal collar of the device. For example, laser cutting or etching may be used to form a tubular member to the integral device.

In this embodiment, the cutting body22is defined by a plurality of struts30integral with the distal collar20and integrally extending to the proximal collar24. However, it is to be noted that the cutting body22may include merely one strut integrally extending from the distal collar20to the proximal collar24. Each strut30is preferably integral with the distal collar20and extends proximally longitudinally therefrom. Preferably, each strut30has a first portion32and a second portion34. In this embodiment, the first portion32is a distal portion, and the second portion34is a proximal portion relative to the device12. The cutting body22is configured to be radially expandable with the expandable balloon to engage the stenotic lesion18for dilatation of the body vessel19during angioplasty. As shown, each strut30is configured to be placed at the stenotic lesion18and to extend longitudinally along the length of the stenotic lesion18.

The device12may be a tubular member comprised of any suitable material such as a superelastic material, stainless steel wire, cobalt-chromium-nickel-molybdenum-iron alloy, cobalt-chrome alloy, or Nitinol. By implementing known techniques, e.g., laser etching, the tubular member may be formed in the shape as depicted inFIGS. 3aand3b, to define the single member integral device. Moreover, it is understood that the device12may be formed of any other suitable material that will result in a self-opening or self-expanding device, such as shape memory alloys. Shape memory alloys have the desirable property of becoming rigid, that is, returning to a remembered state, when heated above a transition temperature.

In this embodiment, each of the distal collar20and the proximal collar24has a longitudinal length of between about 1 millimeter (mm) (about 0.04 inch) and 3 mm (about 0.12 in), and preferably about 2 mm (about 0.08 in). Each of the distal collar20and the proximal collar24may have an inner diameter (ID) of between about 1.3 mm (about 0.05 in) and 1.6 mm (about 0.06 in), and preferably 1.5 mm (0.06 in). Moreover, each of the distal collar20and the proximal collar24may have an outer diameter (OD) of between about 1.5 mm (about 0.05 in) and 3 mm (about 0.12 in), and preferably 2 mm (about 0.08 in). Each of the distal collar20and the proximal collar24may have a constant OD along the longitudinal axis. In this embodiment, each of the struts30has an OD of between about 0.25 mm (about 0.01 in) and 0.76 mm (about 0.03 in), and preferably about 0.36 mm (about 0.014 in). Each of the struts30has a length of between about 40 mm (about 1.5 in) and 60 mm (about 2.3 in), and preferably 50 mm (about 1.9 in). A radial distance between the longitudinal axis and at least one of the struts30in the collapsed configuration is at least the radius of the proximal collar20and the distal collar24.

In this embodiment, the cutting body22comprises four struts30that are formed to be spaced relatively equally apart at about 90 degrees from each adjacent strut30. However, it is to be understood that the number of struts may vary and that the struts may be spaced apart from each other in any other manner without falling beyond the scope of the present invention.

Preferably, each strut defines a focal point or a radial plane of fracture A whereat lacerations to the stenotic lesion18are formed during angioplasty. That is, the struts30cut the plaque of the lesion at focal points to provide the radial planes of fracture A to the lesion, thereby dilating the body vessel19. During angioplasty, each strut30of the cutting body22expands along its respective radial plane of fracture A to engage the stenotic lesion18in the body vessel19. Upon contact with the lesion, the struts30break the plaque in a relatively organized fashion. It has been found that, as the expandable balloon pushes the lesion radially outwardly, the struts cut and allow the plaque to be folded for further dilatation of the body vessel. Furthermore, trauma to the lesion caused by the struts30results in relatively organized lacerations that minimize or lessen the likelihood of restenosis of the body vessel. Thus, the lacerations formed on the lesion allow for a relatively more effective treatment of stenosis.

The struts30may be made of a rigid material, a superelastic material or a shape memory material. For example, the struts30may be made of metals (e.g., stainless steel), Nitinol, or a polymeric material (e.g., high density polyethylene or polypropylene). Preferably, each of the struts30has a diameter of between about 0.014 inch and 0.018 inch.

As mentioned above, each strut30is preferably integral with the distal collar20and the proximal collar24such that the device12is a one-piece device configured to be radially placed about the expandable balloon16. Thus, each first portion32is integral with the distal collar20and extends to the second portion34which is integral with the proximal collar24defining the integrally formed cutting device12. As mentioned above, the device may be integrally formed by manufacturing the device from a tubular member via known manufacturing techniques such as laser etching and cutting. As shown inFIGS. 3aand3b, the struts30integrally extend from the distal collar20and are integral with the proximal collar24. The distal collar20is configured to be disposed about and adjacent the distal end21of the expandable balloon16relative to the device12. The proximal collar24is configured to be disposed about and adjacent the proximal end25of the expandable balloon16relative to the device12.

The condition of the device12is dictated by the condition of the expandable balloon16of the assembly10.FIGS. 4 and 5depict cross-sectional and end views of the device12taken along lines4-4and5-5ofFIG. 2, respectively. As shown, the expansion of the struts30of the device are dictated by the inflation of the angioplasty balloon such that each strut expands along its respective radial plane of fracture to contact and fracture the stenotic lesion18, thereby lessening the likelihood of restenosis.

FIGS. 6a-6ddepict states that the device12takes on during a stenotic procedure as the expandable balloon16is inflated to engage the struts30with the stenotic lesion18.FIG. 6aillustrates the device12in a collapsed state. In the collapsed state, the device12and assembly10may be delivered to and retrieved from a stenotic lesion18. In this embodiment, the outer diameter of the expandable balloon is about 0.3 to 3 millimeters (mm).

FIGS. 6b-6dillustrate the device12in transition states during inflation of the expandable balloon16. During the transition states, the device12may begin contacting the stenotic lesion18. In this embodiment, inFIG. 6b, the outer diameter of the expandable balloon is about 3 to 6 mm. InFIGS. 6cand6d, the outer diameter of the expandable balloon is about 3 to 8 mm.

FIG. 6edepicts the device12in an expanded state as the balloon inflation is completed. In the expanded state, the struts30of the device12are preferably in contact or relatively near contact with the vessel wall and have fractured the stenotic lesion18. The organized fracturing and trauma to the stenotic lesion18provides a lessened likelihood of restenosis of the body vessel. In this embodiment, the outer diameter of the expandable balloon is about 3 to 10 mm.

FIGS. 7a-7bdepict a cutting assembly10that implements the cutting device12for treating a stenotic lesion18of a body vessel in accordance with one embodiment of the present invention. As shown, the assembly10includes the balloon catheter14having a tubular body40portion and an expandable balloon16disposed thereon. The expandable balloon16is preferably attached to and in fluid communication with the tubular body40for angioplasty at the stenotic lesion18. The device12is configured to be disposed about the expandable balloon16for deployment at the stenotic lesion18. The device12is preferably placed about the angioplasty balloon of the angioplasty catheter prior to insertion into the vasculature.

Generally, the balloon catheter14has a proximal end42, a distal end44, and a plastic adapter or hub46to receive assembly10to be advanced therethrough. The hub46is in fluid communication with the balloon for fluid to be passed therethrough for inflation and deflation of the balloon during angioplasty. In one embodiment, the balloon catheter14may include an outer lumen and an inner lumen. The outer lumen is preferably in fluid communication with the expandable balloon16for inflating and deflating the balloon. The inner lumen is formed therethrough for percutaneous guidance through the body vessel. The balloon catheter14is preferably made of a soft, flexible material such as a silicone or any other suitable material. In this embodiment, the inside diameter of the balloon catheter14may range between 0.010 and 0.027 inch.

The size of the expandable balloon16may also vary. For example, the balloon size may range between about 1 and 10 millimeters in diameter. The expandable balloon16has distal and proximal portions. The expandable balloon16may be made of any suitable material such as low density polymer material (e.g., polyethylene or polypropylene) or polyvinyl chloride (PVC).

The assembly10further includes a wire guide54which via an introducer sheath56(discussed in greater detail below) is percutaneously inserted to provide a path for the balloon catheter14within the vasculature of a patient. The balloon catheter14is configured to be disposed about the wire guide54for percutaneous guidance through the vasculature. The size of the wire guide54is based on the inside diameter of the introducer sheath56.

As mentioned above, the assembly10further includes a polytetrafluoroethylene (PTFE) introducer sheath56for percutaneously introducing the wire guide54and the balloon catheter14in vasculature. Of course, any other suitable material may be used without falling beyond the scope or spirit of the present invention. The introducer sheath56is percutaneously inserted into the vasculature of the patient. The sheath may have a size of about 3-French to 8-French and allows the balloon catheter14to be inserted therethrough to the deployment location in the body vessel. In one embodiment, the sheath receives the balloon catheter14and the device12, and provides stability thereto at the deployment location.

The assembly10may further include an outer catheter60disposed co-axially about the balloon catheter14and within the introducer sheath56. As shown, the outer catheter60is preferably configured to house the balloon catheter14and the device12during delivery and retrieval thereof to and from the stenotic lesion18. The outer catheter60is preferably advanced with the balloon catheter14and the device12to the deployment location. When the distal end of the expandable balloon16of the balloon catheter14is placed across the stenotic lesion18in the body vessel, the expandable balloon16may then be inflated preferably with saline. For deployment of the expandable balloon16and the cutting device12, the outer catheter60is then retracted to expose the device12and angioplasty balloon at the stenotic lesion18. The angioplasty balloon is inflated, and both the device12and balloon expands to break plaque of the stenotic lesion18.

It is to be understood that the assembly10described above is merely one example of an assembly10that may be used to deploy the capturing device12in a body vessel. Of course, other apparatus, assemblies, and systems may be used to deploy any embodiment of the capturing device12without falling beyond the scope or spirit of the present invention.

FIG. 8illustrates a flow chart depicting one method110for treating a stenotic lesion18in a body vessel, implementing the assembly10mentioned above. The method110comprises percutaneously introducing an expandable balloon16at a stenotic lesion18in the body vessel in box112. The method110further comprises disposing the integrally formed cutting device12having the C-shaped configuration coaxially about the expandable balloon16for angioplasty of the stenotic lesion18in the body vessel. The method110further includes passing saline through the balloon catheter14to the expandable balloon16to contact the balloon and the device12on the stenotic lesion18. The method110further includes inflating the expandable balloon16and expanding in box114the device12for contact with the stenotic lesion18. The method110further comprises fracturing in box116the stenotic lesion18in the body vessel on each radial plane of fracture with the balloon and the device12.

FIGS. 9 through 13billustrate an atherosclerosis cutting device and assembly210in accordance with another embodiment of the present invention. As shown, the assembly210includes similar components as in the assembly10depicted inFIGS. 1-3band7aand7b. For example, the wire guide54, outer catheter60, and introducer sheath56of the assembly10inFIGS. 1-2are similar to the wire guide254, outer catheter260, and introducer sheath256of the assembly210inFIGS. 9-12.

However, in this embodiment, the distal collar220and the proximal collar224of the cutting device212are each formed in the shape of a ring, solidly and integrally, defining a ring configuration relative to an end view. Preferably, the distal and proximal collars220,224include an expandable body230integral therefrom. Due to the ring configuration formed on each or both of the collars220,224the device212is preferably slid and disposed about the expandable balloon prior to treatment of the stenotic lesion. Thus, during treatment, the device212is configured to be percutaneously advanced with the balloon catheter.

FIGS. 14 and 15illustrate an integrally formed atherosclerosis cutting device312in accordance with another embodiment of the present invention. As shown, the device312includes similar components as in the device12depicted inFIGS. 1-3band7aand7b. For example, the distal collar20, cutting body22, and the proximal collar24of the device12inFIGS. 3aand3bare similar to the distal collar320, cutting body322, and proximal collar324inFIGS. 14 and 15. However, in this embodiment, the device312further comprises a base member326integrally connected with the proximal collar324opposite the cutting body320. As shown, the base member326is integrally attached to the proximal collar324and extends proximally to a predetermined length. Preferably, the base member is a tubular member integrally formed with the component of the device from a single cannular tube. As mentioned above, this may be achieved by known manufacturing methods such as laser etching or cutting.

In use, the device312may be disposed about a balloon catheter having an expandable balloon, such as the balloon catheter mentioned in the assembly above. For treatment of a stenotic lesion, the device may be disposed about the balloon catheter before or after the balloon cather is advanced through an outer catheter for placement at the stenotic lesion in a body vessel. The device312in this embodiment provides the medical practitioner with procedural alternatives. For example, in the event it is determined that pre-dilitation, primary dilitation, and post-dilatation stages are advantageous using the same balloon catheter, the device may be selectively used during the primary dilation stage without retracting the balloon catheter from the patient, lessening any risk of potential trauma and shortening the time of procedure. With the length of the base member, the device may be percutaneously introduced and retracted through the body vessel, using the balloon catheter as the guide.

In this embodiment, the base member326further may include a distal helical or spiral cut327for kink resistance and torque transfer. As shown, the helical cut327is formed adjacent the proximal collar324and may extend a predetermined length, e.g., between about 80 cm and 130 cm. Referring toFIG. 15, the base member326further includes a smooth portion328located proximal the distal helical cut327. As shown, the smooth portion328may proximally extend from the distal helical cut327for a predetermined length, e.g., between about 5 cm and 25 cm.

The device12may be comprised of any suitable material such as a superelastic material, stainless steel wire, cobalt-chromium-nickel-molybdenum-iron alloy, or cobalt-chrome alloy. It is understood that the device12may be formed of any other suitable material that will result in a self-opening or self-expanding device, such as shape memory alloys. Shape memory alloys have a property of becoming rigid, that is, returning to a remembered state, when heated above a transition temperature. A shape memory alloy suitable for the present invention may comprise Ni—Ti available under the more commonly known name Nitinol. When this material is heated above the transition temperature, the material undergoes a phase transformation from martensite to austenic, such that material returns to its remembered state. The transition temperature is dependent on the relative proportions of the alloying elements Ni and Ti and the optional inclusion of alloying additives.

In one alternate embodiment, the device12may be made from Nitinol with a transition temperature that is slightly below normal body temperature of humans, which is about 98.6° F. Although not necessarily a preferred embodiment, when the device12is deployed in a body vessel and exposed to normal body temperature, the alloy of the device12will transform to austenite, that is, the remembered state, which for one embodiment of the present invention is the expanded configuration when the device12is deployed in the body vessel. To remove the device12, the device12is cooled to transform the material to martensite which is more ductile than austenite, making the device12more malleable. As such, the device12can be more easily collapsed and pulled into a lumen of a catheter for removal.

In another alternate embodiment, the device12may be made from Nitinol with a transition temperature that is above normal body temperature of humans, which is about 98.6° F. Although not necessarily a preferred embodiment, when the device12is deployed in a body vessel and exposed to normal body temperature, the device12is in the martensitic state so that the device12is sufficiently ductile to bend or form into a desired shape, which for the present invention is an expanded configuration. To remove the device12, the device12is heated to transform the alloy to austenite so that the device12becomes rigid and returns to a remembered state, which for the device12in a collapsed configuration.

While the present invention has been described in terms of preferred embodiments, it will be understood, of course, that the invention is not limited thereto since modifications may be made to those skilled in the art, particularly in light of the foregoing teachings.