Patent Publication Number: US-2019192270-A1

Title: Pedal thromboembolic protection device

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     The application is a continuation of U.S. patent application Ser. No. 14/716,706, filed May 19, 2015, entitled “PEDAL THROMBOEMBOLIC PROTECTION DEVICE,” the entire disclosure of which is incorporated by reference. 
    
    
     TECHNICAL FIELD 
     Embodiments relate to a thromboembolic protection device that prevents the free flow of embolism-creating particles that are created during peripheral vascular interventions. 
     BACKGROUND 
     Peripheral artery disease (PAD) includes stenosis and occlusion of upper- or lower-extremity arteries due to atherosclerotic or thromboembolic disease. PAD represents a spectrum of disease severity, encompassing both asymptomatic and symptomatic disease. In PAD, as blood vessels narrow, arterial flow into the extremities worsens, and symptoms may manifest either as classic intermittent claudication (IC) or as atypical claudication or leg discomfort. As the disease progresses, patients may develop more severe claudication, with reduced walking distance and eventually with rest pain. In 5 to 10 percent of cases, claudication progresses to a worsened severity of the disease, called critical limb ischemia (CLI)—defined as ischemic rest pain for more than 14 days, ulceration, or tissue loss/gangrene. Patients with CLI have a mortality of 25 percent at one year. 
     Multiple types of interventions are used for revascularization in patients with PAD, including open surgery, angioplasty (e.g., cryoplasty or angioplasty with drug-coated, cutting, or standard angioplasty balloons), stenting (e.g., with self-expanding or balloon-expandable stents are available), and atherectomy (e.g., using laser, directional, orbital, or rotational atherectomy devices). With improvements in endovascular techniques and equipment, the use of balloon angioplasty, stenting, and atherectomy has led to application of endovascular revascularization to a wider range of patients, both among those with more severe symptoms and those with less severe symptoms. However, such interventions frequently involve first traversing a stenosis with a wire, catheter, or treatment device, which poses a risk of embolizing debris even prior to the intervention 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Embodiments will be readily understood by the following detailed description in conjunction with the accompanying drawings. Embodiments are illustrated by way of example and not by way of limitation in the figures of the accompanying drawings. 
         FIGS. 1A and 1B  illustrate an example of an embolism protection device in an expanded state, shown in a perspective view ( FIG. 1A ) and a partial cutaway view ( FIG. 1B ); 
         FIGS. 2A and 2B  include an exploded view ( FIG. 2A ) and a cross-sectional view ( FIG. 2B ) illustrating how the embolism protection device shown in  FIGS. 1A and 1B  may be maintained in a compressed state inside a deployment catheter; 
         FIG. 3  illustrates the embolism protection device shown in  FIGS. 1A and 1B  in the process of being deployed from the deployment catheter; 
         FIGS. 4A and 4B  illustrate the major arteries of the foot ( FIG. 4A ) and an example of a method of using the embolism protection device of  FIGS. 1A and 1B  in the dorsalis pedis artery during an intervention on a CTO upstream of the device ( FIG. 4B ); 
         FIG. 5  illustrates an example of using the embolism protection device of  FIGS. 1A and 1B  in the popliteal artery; and 
         FIGS. 6A and 6B  illustrate an example of an embolism protection device having a plurality of longitudinal compliant support members shown in the closed ( FIG. 6A ) and open ( FIG. 6B ) positions, all in accordance with various embodiments. 
     
    
    
     DETAILED DESCRIPTION OF DISCLOSED EMBODIMENTS 
     In the following detailed description, reference is made to the accompanying drawings which form a part hereof, and in which are shown by way of illustration embodiments that may be practiced. It is to be understood that other embodiments may be utilized and structural or logical changes may be made without departing from the scope. Therefore, the following detailed description is not to be taken in a limiting sense, and the scope of embodiments is defined by the appended claims and their equivalents. 
     Various operations may be described as multiple discrete operations in turn, in a manner that may be helpful in understanding embodiments; however, the order of description should not be construed to imply that these operations are order dependent. 
     The description may use perspective-based descriptions such as up/down, back/front, and top/bottom. Such descriptions are merely used to facilitate the discussion and are not intended to restrict the application of disclosed embodiments. 
     The terms “coupled” and “connected,” along with their derivatives, may be used. It should be understood that these terms are not intended as synonyms for each other. Rather, in particular embodiments, “connected” may be used to indicate that two or more elements are in direct physical or electrical contact with each other. “Coupled” may mean that two or more elements are in direct physical or electrical contact. However, “coupled” may also mean that two or more elements are not in direct contact with each other, but yet still cooperate or interact with each other. 
     For the purposes of the description, a phrase in the form “A/B” or in the form “A and/or B” means (A), (B), or (A and B). For the purposes of the description, a phrase in the form “at least one of A, B, and C” means (A), (B), (C), (A and B), (A and C), (B and C), or (A, B and C). For the purposes of the description, a phrase in the form “(A)B” means (B) or (AB) that is, A is an optional element. 
     The description may use the terms “embodiment” or “embodiments,” which may each refer to one or more of the same or different embodiments. Furthermore, the terms “comprising,” “including,” “having,” and the like, as used with respect to embodiments, are synonymous. 
     Embodiments herein provide embolism protection devices that may be deployed in the peripheral arterial system for the collection of loosened or floating debris, such as embolic material dislodged during or thrombi formed as a result of a peripheral intervention, such as an angioplasty, stenting, or atherectomy. Prior to the present disclosure, most of the filters used to prevent embolism during or after peripheral interventions were devices that were advanced through the vasculature from above (e.g., proximal to) the lesion, and deployed into the anatomy distal to the lesion. During this process, the filter and the wire had to traverse the lesion in order to be placed, which created a risk of embolization even prior to the intervention. 
     By contrast, various embodiments disclosed herein are embolism protection devices that are designed to be inserted distal to lesion in a lower limb artery via one of the arteries of the foot, such as the dorsalis pedis, posterior tibialis, or peroneal (fibular) artery. In various embodiments, this approach may obviate the problem of needing to traverse lesions to place a filter device, and it therefore may avoid the risk of dislodging the detritus that could cause an embolism. 
     Once positioned, the embolism protection device may be allowed to open such that it filters the blood and excludes any plaques, thrombi, or other emboli that may be dislodged, for example due to mechanical and drag forces exerted upon them as devices traverse the area of plaque or stenosis. Thus, in various embodiments, the device may prevent atherosclerotic material and other debris from entering the circulation, and may protect the subject from embolism associated with peripheral interventions. 
     An embolus can be any particle comprising a foreign or native material that enters the vascular system with potential to cause occlusion of blood flow. Emboli can be formed from aggregated fibrin, red blood cells, collagen, cholesterol, plaque, fat, calcified plaque, bubbles, arterial tissue, and/or other miscellaneous fragments. Each dislodged fragment, or embolus, is carried along by the blood flow until it becomes lodged or trapped in a smaller vessel and occludes blood flow, creating an embolism. Since emboli reduce or cut off blood flow, damage to the body may result, such as tissue damage. 
     In various embodiments, the embolism protection device may have a first (distal) portion formed from a thin, compliant mesh material having a pore size that is sufficiently large to allow blood to flow freely therethrough, but that is sufficiently small to prevent potential thrombi and emboli from passing through. In various embodiments, the thin, compliant mesh material may be made from Nitinol™, and in some embodiments, it may have a slippery surface to ease the insertion of the device into the vascular system. In various embodiments, the compliant mesh material may be supported by a compliant wire support member that may be formed from a material having a shape memory function, such as Nitinol™ wire. In various embodiments, the compliant wire support member may be coupled to or otherwise configured to stabilize and/or stretch the compliant mesh material. In some embodiments, the compliant wire support member may be biased to adopt an open configuration (e.g., having a larger diameter in the open state than in the closed state), and may be sized and shaped to secure or stretch or open the compliant mesh material to abut the full circumference of an arterial wall. 
     In various embodiments, the compliant mesh material and compliant wire support member also may be compressed or collapsed to adopt a very small outer circumference and/or outer diameter, for instance by being inserted into the lumen of a small diameter deployment catheter, such that the collapsed embolism protection device may be advanced to a desired part of the peripheral arterial system. 
     In some embodiments, the compliant mesh filter portion of the embolism protection device may be generally conical or cup-shaped, and the apex of the cone or cup may have an opening that extends to form (or couples to) a slender, solid-walled catheter portion having a lumen extending therethrough. In some embodiments, the aperture in the apex of the cone or cup shaped mesh filter portion may communicate with the lumen of the catheter portion, for example, so that debris captured in the mesh filter may be evacuated from the body via the catheter portion. In some embodiments, the proximal end of the catheter portion (e.g., nearest the physician and outside the body) may include a threaded or Luer-lock coupling mechanism, for example for coupling to a syringe or stopcock. In some embodiments, the syringe or stopcock may be used to draw debris captured by the embolism protection device through the catheter portion and out of the body. 
     In various embodiments, in order to place the embolism protection device, access is gained with a needle in one of the arteries of the foot, such as the dorsalis pedis, posterior tibialis, or peroneal (fibular) artery, and a small wire, such as a 0.014 inch wire, is inserted into the artery and advanced to a position distal to the lesion. In various embodiments, the needle is then withdrawn, leaving the wire in place. The embolism protection device may then be advanced (in a compressed state inside a deployment catheter) over the wire. In various embodiments, the wire may be withdrawn once the filter is in place, and before the embolism protection device is unsheathed. 
     In various embodiments, once the embolism protection device has been placed in an appropriate position, the deployment catheter may be slowly withdrawn, unsheathing the device progressively until the device is fully unsheathed. In various embodiments, unsheathing the embolism protection device may allow the compliant wire support member to fully open the compliant mesh portion abut against the walls of the artery, thus preventing any debris from passing beyond that point. In various embodiments, the compliant mesh portion and the compliant wire support member are positioned entirely within the artery, while the catheter portion extends out of the body. 
     In various embodiments, a stopcock or syringe may be coupled to the outside (proximal) portion of the device to cause hemostasis, and in various embodiments, the stopcock may can be opened periodically or the syringe used to withdraw blood and debris to keep the filter clear of debris. In various embodiments, upon completion of the procedure, the embolism protection device may be simply pulled out in its expanded state because, due to the low profile and pliable material of the device, the injury potential is very low. Alternatively, in various embodiments, theembolism protection device may be resheathed and the device withdrawn in its compressed state. 
     In various embodiments, the mesh material of the compliant mesh portion may have a pore size that is sized to allow vessel perfusion (e.g., that allows the passage of red blood cells), while still preventing potential emboli (e.g., atherothrombotic debris) from passing. In various embodiments, the embolism protection device may have an elongated shape, with a total length of about 10-15 cm, and an expanded width of about 3-7 mm. 
       FIGS. 1A and 1B  illustrate an example of an embolism protection device in an expanded state, shown in a perspective view ( FIG. 1A ) and a partial cutaway view ( FIG. 1B ), in accordance with various embodiments. As shown in  FIG. 1A , the embolism protection device  100  may include a first (distal) portion  102  that may be formed from a compliant mesh material  104  and a compliant wire support member  106  that biases the first portion  102  into a funnel having a generally conical or cup-like shape. In various embodiments, the first portion  102  may be sized and shaped such that it may be inserted into an artery of the foot in a compressed state, and it may be biased such that it naturally assumes a cone or cup shape when released. In various embodiments, the outer diameter of the distal portion  102  may be sized and shaped to abut the walls of the artery when in an open state. 
     In various embodiments, the first portion  102  may be formed from a thin, hydrophilic, compliant mesh material  104  having a pore size that is sufficiently large to allow red blood cells and other blood components to flow freely therethrough, but that is sufficiently small to prevent potential thrombi and emboli from passing through. For example, in some embodiments, the compliant mesh material  104  may have a pore size of from about 80 microns to about 100 microns, or from about 90 microns to about 100 microns. In various embodiments, a compliant wire support member  106  may be disposed within or otherwise coupled to the funnel-shaped compliant mesh material  104 , such that it provides support to the compliant mesh material  104  and helps to support and form the compliant mesh material  104  in the generally conical or cup shape. In various embodiments, the compliant wire support member  106  may be formed from a material having a shape memory function, such as Nitinol™ wire, and may be biased to assume an open configuration. 
     As shown in  FIG. 1B , the first portion  102  of the embolism protection device  100  may include an aperture  108  at the apex or base of the funnel that extends to form (or couples to) a slender, solid-walled catheter portion  110  having a lumen  111  extending therethrough. In some embodiments, the aperture  108  in the apex of the cone or cup shaped first portion  102  may communicate with the lumen of the catheter portion  110 , for example, so that debris captured in the compliant mesh material  104  may be evacuated from the body via the catheter portion  110 . In some embodiments, the proximal end of the catheter portion (e.g., the end nearest the physician and outside the body) may include a threaded or Luer-lock coupling mechanism  112 , for example for coupling to a syringe or stopcock. In some embodiments, the syringe or stopcock may be used to draw debris captured by the embolism protection device through the catheter portion and out of the body. 
       FIGS. 2A and 2B  include an exploded view ( FIG. 2A ) and a cross-sectional view ( FIG. 2B ) illustrating how the embolism protection device shown in  FIGS. 1A and 1B  may be maintained in a compressed state inside a deployment catheter, in accordance with various embodiments. In some embodiments, the embolism protection device  100  may be collapsed when it is inserted into a narrow-diameter catheter, such as the illustrated deployment/retrieval catheter  120 . As shown in  FIG. 2B , in some embodiments, the catheter portion  110  of the compressed embolism protection device  100  may extend beyond the proximal end of the deployment catheter  120 , and may be grasped or manipulated by a user, for example during placement of the device. 
       FIG. 3  illustrates the embolism protection device shown in  FIGS. 1A and 1B  in the process of being deployed from the deployment catheter, in accordance with various embodiments. One the deployment/retrieval catheter  120  has been advanced to a desired position within the desired artery, such as the dorsalis pedis, the embolism protection device  100  may be unsheathed and allowed to expand. In various embodiments, because the compliant wire support member  106  is biased in an open position, withdrawing the deployment catheter  120  while leaving the embolism protection device  100  in place may allow the compliant wire support member  106  to expand the first portion  102  as it is released from the deployment catheter  120 . 
       FIGS. 4A and 4B  illustrate the major arteries of the foot ( FIG. 4A ) and an example of a method of using the embolism protection device of  FIGS. 1A and 1B  in the dorsalis pedis artery during an intervention on a CTO upstream of the device ( FIG. 4B ), in accordance with various embodiments. Depending on the location of the CTO in the subject, and the particular vascular anatomy of the subject, the embolism protection device  100  may be deployed in the dorsalis pedis  122  as illustrated in  FIG. 4B , or it may be deployed in the posterior tibialis  124  or peroneal (fibular) artery  126 . In various embodiments, any of these arteries may receive the embolism protection devices disclosed herein, and may be selected based on proximity to the lesion being treated. As illustrated in  FIG. 4B , once the embolism protection device  100  has been deployed in a desired artery, the deployment catheter  120  may be withdrawn to allow the compliant wire support member  106  to expand within the artery  122 , thus abutting and contacting the full circumference of the arterial wall. 
     The intervention may then be performed upstream at the site of the occlusion via equipment that is advanced from the femoral artery, and any debris generated from the intervention may be captured by the compliant mesh material of the embolism protection device  100 . If desired, in some embodiments, any captured debris may be withdrawn from the body through the embolism protection device, for example via a syringe  114 . Once the intervention is complete, the embolism protection device  100  may be withdrawn from the artery  122 . In some embodiments, prior to removal, the deployment catheter  102  may be advanced over the compliant wire support member  106 , thereby collapsing the embolism protection device  100  prior to removal. In other embodiments, the embolism protection device  100  may be simply pulled from the artery  122  because, due to its compliant nature, it may be removed atraumatically even in the expanded state. 
       FIG. 5  illustrates another example of using the embolism protection device of  FIGS. 1A and 1B , wherein the embolism protection device is placed in the popliteal artery. In some embodiments, it may be advantageous to advance the embolism protection device  100  further proximally (e.g., further up the leg, towards the trunk) in order to protect multiple arteries and arterial branches in the foot and lower leg when the occlusion is located more praximally, such as in the superficial femoral artery. In these embodiments, the embolism protection device  100  may be advanced through one of the arteries of the foot, such as the dorsalis pedis  122 , posterior tibialis  124 , or peroneal (fibular) artery (not shown) until it reaches the popliteal artery  128 . Once it has been positioned in this fashion, the device may be deployed and used as described above with reference to  FIGS. 4A and 4B . 
       FIGS. 6A and 6B  illustrate an example of an embolism protection device having a plurality of longitudinal compliant support members shown in the closed ( FIG. 6A ) and open ( FIG. 6B ) positions, in accordance with various embodiments. In various embodiments, instead of the spiral-shaped compliant support members shown in  FIGS. 1A and 1B , the embolism protections device  600  may instead include a plurality of longitudinal compliant support members  606  that may be biased in an open position ( FIG. 6B ), such that they open the first portion  602  of the embolism protection device  600  when released from the deployment catheter  620 , stretching the compliant mesh  604  into a funnel or inverted umbrella shape. In some embodiments, the compliant mesh  604  may include a plurality of longitudinal pleats  630  corresponding to each of the plurality of longitudinal compliant support members  606 , which pleats  630  allow the first portion  602  to compress tightly and fit within the deployment catheter  620  ( FIG. 6A ). 
     Although certain embodiments have been illustrated and described herein, it will be appreciated by those of ordinary skill in the art that a wide variety of alternate and/or equivalent embodiments or implementations calculated to achieve the same purposes may be substituted for the embodiments shown and described without departing from the scope. Those with skill in the art will readily appreciate that embodiments may be implemented in a very wide variety of ways. This application is intended to cover any adaptations or variations of the embodiments discussed herein. Therefore, it is manifestly intended that embodiments be limited only by the claims and the equivalents thereof.