Embolic protection device having a reticulated body with staggered struts

Abstract

An embolic protection device for capturing emboli during treatment of a stenotic lesion in a body vessel is disclosed. The device comprises a basket and a filter attached to the basket. The basket has a deployed state and an undeployed state. The basket includes a reticulated body having an outer diameter. The reticulated body includes a plurality of struts connected together in a singly staggered configuration distally along a longitudinal axis to a distal end. The plurality of struts of the reticulated body is configured to fold along the longitudinal axis. The basket has a proximal stem proximally extending from the body. The filter portion has a lip attached to the distal end defining an opening of the filter portion when the basket is in the deployed state for capturing emboli. The filter portion extends from the lip to a filter end.

Description

BACKGROUND OF THE INVENTION

The present invention relates to medical devices. More particularly, the present invention relates to embolic protection devices and methods for capturing emboli within a body vessel.

Embolic protection to capture emboli within the vasculature is a growing concern in the medical industry. Currently, there are a number of treatments for embolic protection to prevent emboli and blood clots from traveling within the vasculature to create undesirable medical conditions, e.g., ischemic stroke, brain aneurysm, pulmonary embolism. For example, vena cava filters are more commonly being used for trapping blood clots and emboli in the vena cava filter to prevent pulmonary embolism. Also, anti-platelet agents and anticoagulants may be used to breakdown blood clots. Moreover, snares and baskets (e.g., stone retrieval baskets) are more commonly used for retrieving urinary calculi. Additionally, occlusion coils are commonly used to occlude aneurysms and accumulate thrombi in a body vessel.

Treatments for a stenotic lesion provide a potential in releasing blood clots and other thrombi plaque in the vasculature of the patient. One example is the treatment for a carotid artery stenosis. 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 process is called atherosclerosis.

Depending on the degree of stenosis and the patient's overall condition, carotid artery stenosis has been treated with surgery. The procedure (with its inherent risks) is called carotid endarterectomy, which removes the plaque from the arterial walls. Carotid endarterectomy has proven to benefit patients with arteries substantially narrowed, e.g., by about 70% or more. For people with less narrowed arteries, e.g., less than about 50%, an anti-clotting drug may be prescribed to reduce the risk of ischemic stroke. Examples of these drugs are anti-platelet agents and anticoagulants.

Carotid angioplasty is a more recently developed 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.

During the stenosis procedure however, there is a risk of such blood clots and thrombi being undesirably released into the blood flow within the vasculature. Embolic or distal protection devices have been implemented to capture emboli from a stenotic lesion undergoing angioplasty. However, many current embolic protection devices restrict flow when deployed within the vasculature of the patient. Moreover, many embolic protection devices are relatively difficult to collapse and retrieve after the need for such device in the vasculature passes.

Thus, there is a need to provide an improved device and method for distally protecting and capturing emboli within a body lumen during a stenosis procedure.

BRIEF SUMMARY OF THE INVENTION

The present invention generally provides an embolic protection device that minimizes restricted flow when deployed within the vasculature of a patient and that is relatively easy to retrieve.

In one embodiment, the present invention provides an embolic protection device for capturing emboli during treatment of a stenotic lesion in a body vessel. The device comprises a basket and a filter connected to the basket. In this embodiment, the basket has a deployed state and an undeployed state. The basket includes a reticulated body having an outer diameter. The reticulated body includes a plurality of struts connected together in a singly staggered configuration distally along a longitudinal axis to a distal end. The plurality of struts of the reticulated body is configured to fold along the longitudinal axis. The basket further has a proximal stem proximally extending from the body. The filter portion has a lip attached to the distal end defining an opening of the filter portion when the basket is in the deployed state for capturing emboli. The filter portion extends from the lip to a filter end.

In another embodiment, the present invention provides an embolic protection assembly for capturing emboli during treatment of a stenotic lesion in a body vessel. The assembly comprises a balloon catheter having a tubular body portion and an expandable balloon attached to and in fluid communication with the tubular body portion for angioplasty at the stenotic lesion. The expandable balloon has distal and proximal portions. The assembly further comprises an embolic protection device coaxially disposed within the balloon catheter during treatment of the stenotic lesion in the body vessel. The device comprises the basket and the filter portion.

In another example, the present invention provides a method for embolic protection during treatment of a stenotic lesion in a body vessel. The method comprises percutaneously introducing a balloon catheter in the body vessel. The balloon catheter has a tubular body portion and an expandable balloon attached to and in fluid communication with the tubular body portion for angioplasty at the stenotic lesion. The method further comprises disposing the embolic protection device in an undeployed state coaxially with the balloon catheter. The method further comprises deploying the device in an deployed state downstream from the stenotic lesion to capture emboli during treatment of 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.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an environment view of an embolic protection device in accordance with one embodiment of the present invention;

FIG. 2 is a perspective view of the emboli protection device of FIG. 1;

FIG. 3 is a plan view of the embolic protection device of FIG. 1;

FIG. 4 is an end view of the embolic protection device in FIG. 1;

FIG. 5 is a side view of the embolic protection device in a collapsed configuration in accordance with one embodiment of the present invention;

FIG. 6 a is a side view of an embolic protection assembly for capturing emboli during treatment of a stenotic lesion in accordance with one embodiment of the present invention;

FIG. 6 b is an exploded side view of the assembly in FIG. 6a;

FIG. 7 is a flow chart of one method for embolic protection during treatment of a stenotic lesion in a body vessel; and

FIG. 8 is a flow chart of one method for retrieving an embolic protection device for post-treatment of a stenotic lesion in a body vessel.

DETAILED DESCRIPTION OF THE INVENTION

The present invention generally provides an embolic protection device that minimizes restricted flow when deployed within the vasculature of a patient and that is relatively easy to retrieve after the risk of releasing blood clots and thrombi within the vasculature has passed. Embodiments of the present invention generally provide an embolic protection device comprising a basket having a reticulated body including a plurality of struts connected together in a singly staggered configuration distally along a longitudinal axis to an open distal end. The singly staggered configuration allows for relatively easy retrieval of the device. Moreover, the basket extends along the longitudinal axis having a substantially constant outer diameter to minimize restricted flow when deployed within the vasculature of a patient.

FIG. 1 illustrates an embolic protection device 10 for capturing emboli during treatment of a stenotic lesion in a body vessel 11 in accordance with one embodiment of the present invention. As shown in FIGS. 1 and 2, the device 10 comprises a basket 12 and a filter portion 14 attached to the basket 12 for capturing emboli in the body vessel 11. The basket 12 extends from an open proximal end 16 and an open distal end 18, and is configured to have an expanded state and a collapsed state.

In this embodiment, the basket 12 includes a reticulated body 20 extending along an outer diameter when in the expanded state. The reticulated body 20 includes a plurality of struts 22 distally connected together in a singly staggered configuration relative to a longitudinal axis A of the basket 12. As shown, the singly staggered configuration of the plurality of struts 22 distally extends from a proximal portion 24 of the reticulated body 20 along the longitudinal axis A to a distal portion 26 thereof. In the expanded state, each of the struts 22 of the reticulated body 20 is configured to fold singly in pairs along the longitudinal axis A to the collapsed state. As will be described in greater detail below, the singly staggered configuration allows the device 10 to be relatively easily collapsed and retrieved when deployed within the vasculature of a patient.

As shown in FIGS. 2 and 3, the reticulated body 20 is formed so that each strut 22 is singly connected to another strut 22 in pairs relative to the longitudinal axis of the basket 12. Preferably, the struts 22 are connected together at pivotal joints 30 along the reticulated body 20. In this embodiment, one pair of struts 22 is connected at one pivotal joint 30. Each of the pivotal joints 30 is configured to allow a pair of struts 22 to singly fold distally along the longitudinal axis. As shown, a pair of struts 22 distally extends from a single pivotal joint 30 at the proximal stem 32. In this embodiment, two struts 22 are disposed on and extend from the proximal stem 32 and up to ten struts 22 may be formed at the distal portion 26 of the basket 12. When each of the pairs of struts 22 is folded at the pivotal joints 30, the reticulated body 20 is collapsed to its collapsed state for delivery or retrieval of the device 10. This feature allows a catheter to circumferentially ride over each pivotal joint 30 for relatively easy collapse and retrieval of the device 10.

The reticulated body 20 distally extends from the proximal portion 24 to the distal portion 26 along the outer diameter. Preferably, the reticulated body 20 extends substantially constantly along the outer diameter when in the expanded state. As shown in FIGS. 3 and 4, the reticulated body 20 extends along the outer diameter and maintains substantially the same or constant diameter therealong from the proximal portion 24 to the distal portion 26 of the reticulated body 20. In the expanded state, the basket 12 avoids placement at or near the center of the body vessel in which it is deployed. Thus, this feature lessens restricted blood flow when the device 10 is deployed within the vasculature of a patient.

Preferably, the number of struts 22 and pivotal joints 30 on the reticulated body 20 distally increases in a singly staggered configuration along the longitudinal axis to the open distal end. As shown, struts 22 at the distal portion 26 of the reticulated body 20 are connected together along the outer diameter, defining the open distal end 18 of the basket 12.

As mentioned above, FIG. 4 illustrates that the reticulated body 20 maintains a substantially constant outer diameter relative to the longitudinal axis. As shown, the outer diameter of the body is substantially constant and extends between the proximal end and distal end of the reticulated body 20. In this embodiment, the term “constant outer diameter” of the body or “substantially constant outer diameter” of the body means that the body extends along the longitudinal axis having about the same outer diameter. For instance, if the outer diameter of the body at the proximal portion 24 is about 5 millimeters (mm), then the outer diameter of the body along the remainder of the body is also about 5 mm.

FIG. 5 illustrates the device 10 in its collapsed or closed state in accordance with one embodiment of the present invention. As shown, the device 10 has a reduced diameter, occupying a cross-sectional profile less than the outer diameter of the device 10 in the expanded state. The pivotal joints 30 of the reticulated body 20 singly increase distally along the longitudinal axis of the device 10. As shown in FIG. 5, the reticulated body 20 in the collapsed state distally increases in width in a singly staggered configuration. For example, the reticulated body 20 in the collapsed configuration includes pairs of folded struts 22 singly staggered at their respective pivotal joints 30 which distally increase in number, thereby distally increasing the width as the body distally extends.

FIGS. 2-4 further depict the basket 12 having a proximal stem 32. As shown, the proximal stem 32 proximally extends from the proximal portion 24 of the basket 12 along the outer diameter thereof. Thus, the proximal stem 32 is positioned off-centered to allow maximum blood flow through the device 10 when deployed in a body vessel. The proximal stem 32 may proximally extend from the basket 12 and take on any suitable shape along the outer diameter of the basket 12. For example, the proximal stem 32 may take on a shape of an elongated member that may be disposed through a lumen of a balloon catheter 42 for placement of the embolic protection device 10 during treatment of a stenotic lesion. However, it is understood that the proximal stem 32 may take on other shapes without falling beyond the scope or spirit of the present invention.

As mentioned, the proximal stem 32 extends in alignment with the outer diameter of the basket 12 relative to a radial axis of the device 10. This allows for more effective filtering and lessens the risk of blood flow issues within the vasculature during angioplasty, while maintaining a relatively easy way for delivery and retrieval. However, the proximal stem 32 may be configured as desired to extend circumferentially within, in non-alignment with, the outer diameter of the device 10 relative to the radial axis.

The basket 12 may 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 basket 12 may be formed of any other suitable material that will result in a self-opening or self-expanding basket, 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. A shape memory alloy suitable for the present invention is 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 embodiment, the basket 12 is made from Nitinol with a transition temperature that is slightly below normal body temperature of humans, which is about 98.6° F. Thus, when the basket 12 is deployed in a body vessel and exposed to normal body temperature, the alloy of the basket 12 will transform to austenite, that is, the remembered state, which for one embodiment of the present invention is the expanded configuration when the basket 12 is deployed in the body vessel. To remove the basket 12, the basket 12 is cooled to transform the material to martensite which is more ductile than austenite, making the basket 12 more malleable. As such, the basket 12 can be more easily collapsed and pulled into a lumen of a catheter for removal.

In another embodiment, the basket 12 is made from Nitinol with a transition temperature that is above normal body temperature of humans, which is about 98.6° F. Thus, when the basket 12 is deployed in a body vessel and exposed to normal body temperature, the basket 12 is in the martensitic state so that the basket 12 is sufficiently ductile to bend or form into a desired shape, which for the present invention is an expanded configuration. To remove the basket 12, the basket 12 is heated to transform the alloy to austenite so that the basket 12 becomes rigid and returns to a remembered state, which for the basket 12 in a collapsed configuration.

As shown in FIG. 2, the filter portion 14 has a lip 34 attached to the distal end 18 of the reticulated body 20, defining an opening 36 of the filter portion 14 when the basket 12 is in the expanded state for capturing emboli. The lip 34 may be attached to the distal end by any suitable means including sonic bonding, thermal bonding, or adhesive bonding. As shown in FIGS. 2 and 5, the filter portion 14 extends from the lip 34 to a filter end 38 formed to be a proximally facing concave shape. The opening 36 of the filter portion 14 is configured to face toward the stenotic lesion.

The filter portion 14 may be comprised of any suitable material to be used for capturing emboli from the stenotic lesion during treatment thereof. In one embodiment, the filter portion 14 is made of connective tissue material for capturing emboli. In this embodiment, the connective tissue comprises extracellular matrix (ECM). As known, ECM is a complex structural entity surrounding and supporting cells that are found within mammalian tissues. More specifically, ECM comprises structural proteins (e.g., collagen and elastin), specialized protein (e.g., fibrillin, fibronectin, and laminin), and proteoglycans, a protein core to which are attached are long chains of repeating disaccharide units termed of glycosaminoglycans.

Most preferably, the extracellular matrix is comprised of small intestinal submucosa (SIS). As known, SIS is a resorbable, acellular, naturally occurring tissue matrix composed of ECM proteins and various growth factors. SIS is derived from the porcine jejunum and functions as a remodeling bioscaffold for tissue repair. SIS has characteristics of an ideal tissue engineered biomaterial and can act as a bioscaffold for remodeling of many body tissues including skin, body wall, musculoskeletal structure, urinary bladder, and also supports new blood vessel growth. In many aspects, SIS is used to induce site-specific remodeling of both organs and tissues depending on the site of implantation. In theory, host cells are stimulated to proliferate and differentiate into site-specific connective tissue structures, which have been shown to completely replace the SIS material in time.

In this embodiment, SIS is used to temporarily adhere the filter portion 14 to the walls of a body vessel in which the device 10 is deployed. SIS has a natural adherence or wettability to body fluids and connective cells comprising the connective tissue of a body vessel wall. Due to the temporary nature of the duration in which the device 10 is deployed in the body vessel, host cells of the wall will adhere to the filter portion 14 but not differentiate, allowing for retrieval of the device 10 from the body vessel.

In other embodiments, the filter portion 14 may also be made of a mesh/net cloth, nylon, polymeric material, Teflon, or woven mixtures thereof without falling beyond the scope or spirit of the present invention.

In use, the device 10 expands from the collapsed state to the expanded state, engaging the basket 12 with the body vessel. In turn, the lip 34 of the filter portion 14 expands to open the filter portion 14 for capturing emboli during treatment of the stenotic lesion. After the need for such device 10 in the vasculature passes, the device 10 may be retrieved. In one embodiment, a catheter may be used to move longitudinally about the basket 12 to singly collapse each pivotal joint 30 distally, thereby moving the basket 12 toward the collapsed state.

FIGS. 6 a and 6b depict an embolic protection assembly 40 for capturing emboli during treatment of a stenotic lesion in a body vessel in accordance with another embodiment of the present invention. As shown, the assembly 40 comprises a balloon catheter 42 having a tubular body 44 and an expandable balloon 46 attached to and in fluid communication with the tubular body 44 for angioplasty at a stenotic lesion. In this embodiment, the assembly 40 comprises the embolic protection device mentioned above. The tubular body 44 is preferably made of soft flexible material such as silicon or any other suitable material. In this embodiment, the balloon catheter 42 includes an outer lumen 48 and an inner lumen 50. The outer lumen 48 is in fluid communication with the balloon 46 for inflating and deflating the balloon 46. The inner lumen 50 is formed therethrough for percutaneous guidance through the body vessel.

As shown, the assembly 40 further includes an inner catheter 52 having a distal end 54 through which the balloon catheter 42 is disposed for deployment in the body vessel. The inner catheter 52 is preferably made of a soft, flexible material such as silicon or any other suitable material. Generally, the inner catheter 52 further has a proximal end 56 and a plastic adaptor or hub 58 to receive the embolic protection device and balloon catheter 42 to be advanced therethrough. The size of the inner catheter 52 is based on the size of the body vessel in which it percutaneously inserts, and the size of the balloon catheter 42.

As shown, the assembly 40 may also include a wire guide 60 configured to be percutaneously inserted within the vasculature to guide the inner catheter 52 to a location adjacent a stenotic lesion. The wire guide 60 provides the inner catheter 52 (and balloon catheter 42) a path during insertion within the body vessel. The size of the wire guide 60 is based on the inside diameter of the inner catheter 52.

In one embodiment, the balloon catheter 42 has a proximal fluid hub 62 in fluid communication with the balloon 46 via the outer lumen 48 for fluid to be passed therethrough for inflation and deflation of the balloon 46 during treatment of the stenotic lesion.

As shown, the embolic protection device is coaxially disposed through the inner lumen 50 of the balloon catheter 42 prior to treatment of the stenotic lesion in the body vessel. The distal protection device is guided through the inner lumen 50 preferably from the hub 58 and distally beyond the balloon 46 of the balloon catheter 42, exiting from the distal end of the inner or balloon catheter 42 to a location within the vasculature downstream of the stenotic lesion.

In this embodiment, the apparatus further includes a polytetrafluoroethylene (PTFE) introducer sheath 64 for percutaneously introducing the wire guide 60 and the inner catheter 52 in a body vessel. Of course, any other suitable material may be used without falling beyond the scope or spirit of the present invention. The introducer sheath 64 may have any suitable size, e.g., between about three-french to eight-french. The introducer serves to allow the inner and balloon catheters 42 to be percutaneously inserted to a desired location in the body vessel. The introducer sheath 64 receives the inner catheter 52 and provides stability to the inner catheter at a desired location of the body vessel. For example, the introducer sheath 64 is held stationary within a common visceral artery, and adds stability to the inner catheter 52, as the inner catheter 52 is advanced through the introducer sheath 64 to a dilatation area in the vasculature.

When the distal end 54 of the inner catheter 52 is at a location downstream of the dilatation area in the body vessel, the balloon catheter 42 is inserted therethrough to the dilatation area. The device is then loaded at the proximal end of the balloon catheter 42 and is advanced through the inner lumen 50 thereof for deployment through its distal end. In this embodiment, the proximal stem is used to mechanically advance or push the device 10 through the catheter.

FIG. 7 depicts a flow chart of one method 110 for embolic protection during treatment of stenotic lesion in a body vessel. The method 110 comprises percutaneously introducing the balloon catheter 42 in a body vessel in box 112, after the inner catheter is disposed to a dilatation area within the body vessel. The physician may use any suitable means of verifying the placement of the balloon catheter at a dilatation area, e.g., fluoroscopy.

In this example, the method further comprises disposing the embolic protection device in the collapsed state coaxially with the balloon catheter in box 114, once the balloon catheter is placed at the dilatation area. The method 110 further includes deploying the device in a deployed state downstream from the stenotic lesion to capture emboli during treatment of the stenotic lesion in box 116.

In yet another example of the present invention, FIG. 8 depicts one method 210 of retrieving an embolic protection device for post-treatment of a stenotic lesion in a body vessel. The method comprises providing the embolic protection assembly having the embolic protection device in a deployed state within the body vessel in box 212. The method further comprises singly moving each of the struts about each pivotal joint to collapse the reticulated body in the undeployed state in box 214. The method further includes retracting the embolic protection device in the balloon catheter to retrieve the embolic protection device from the body vessel in box 216.

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.

Claims

1. An embolic protection device for capturing emboli during treatment of a stenotic lesion in a body vessel, the device comprising: a basket having a deployed state and an undeployed state, the basket including a reticulated body having an outer diameter, the reticulated body including a plurality of struts connected together in a singly staggered configuration relative to a longitudinal axis of the basket, the singly staggered configuration of the plurality of struts extending distally from a proximal end of the reticulated body along the longitudinal axis to a distal end, the plurality of struts being connected together at pivotal joints along the reticulated body, each pivotal joint connecting a pair of struts, wherein the number of pivotal joints singly increases distally along the longitudinal axis between the proximal and distal ends to define the singly staggered configuration of the plurality of struts, wherein the reticulated body in the undeployed state distally increases in width in the singly staggered configuration, the distal end defining the greatest width in the undeployed state, the pairs of struts connected by the pivotal joints being configured to singly fold distally along the longitudinal axis from the deployed state to the undeployed state, the basket having a proximal stem proximally extending from the body; anda filter portion having a lip attached to the distal end defining an opening of the filter portion when the basket is in the deployed state for capturing emboli, the filter portion extending from the lip to a filter end.

2. The device of claim 1 wherein the distal end distally extends from the reticulated body along the outer diameter.

3. The device of claim 1 wherein the number of struts on the reticulated body increases in a singly staggered configuration along the longitudinal axis of the reticulated body.

4. The device of claim 3 wherein the number of struts at the proximal stem of the body is one strut and the number of struts at the distal end is up to 10 struts.

5. The device of claim 1 wherein the outer diameter of the body is substantially constant and extends between the proximal stem and distal end of the reticulated body.

6. The device of claim 1 wherein the opening of the filter portion is configured to face toward the stenotic lesion in the body vessel proximal to the closed end thereof.

7. The device of claim 1 wherein the filter portion comprises a net material for capturing emboli from the stenotic lesion.

8. The device of claim 1 wherein the reticulated body is made of shape memory material configured to expand the reticulated body in the deployed state at a first temperature and collapse the reticulated body in the undeployed state at a second temperature.