Patent Publication Number: US-11648028-B2

Title: Methods and apparatus for treating embolism

Description:
CROSS-REFERENCE TO RELATED APPLICATION(S) 
     This application is a continuation of U.S. patent application Ser. No. 15/949,350, filed on Apr. 10, 2018 and entitled Methods and Apparatus for Treating Embolism, which is a continuation of U.S. patent application Ser. No. 14/646,358, filed on May 20, 2015, now issued as U.S. Pat. No. 10,004,531, and entitled Methods and Apparatus for Treating Embolism, which is a 371 U.S. national filing of PCT/US2013/071101, filed on Nov. 20, 2013, and entitled Methods and Apparatus for Treating Embolism, which is a continuation-in-part of U.S. patent application Ser. No. 13/843,742, filed on Mar. 15, 2013, now issued as U.S. Pat. No. 8,784,434 and entitled Methods and Apparatus for Treating Embolism, which claims priority to U.S. Provisional Application Ser. No. 61/750,277 filed Jan. 8, 2013 entitled Devices and Methods for Treatment of Vascular Occlusion and U.S. Provisional Application Ser. No. 61/728,775 filed Nov. 20, 2012 entitled Devices and Methods for Treatment of Vascular Occlusion, all of which are hereby incorporated herein by reference in their entireties. 
    
    
     TECHNICAL FIELD 
     This invention relates to the apparatus and methods of endovascular treatment of blood clots obstructing passageways in the circulatory system and particularly the endovascular treatment of pulmonary embolism. 
     BACKGROUND 
     Thromboembolism is the formation in a blood vessel of a clot (thrombus) that breaks loose (embolizes) and is carried by the blood stream to another location in the circulatory system resulting in a clot or obstruction at that new location. For example, a clot may embolize and plug a vessel in the lungs (pulmonary embolism), the brain (stroke), the gastrointestinal tract, the kidneys, or the legs. Thromboembolism is a significant cause of morbidity (disease) and mortality (death), especially in adults. A thromboembolism can be sudden and massive or it may be small and multiple. A thromboembolism can be any size and a thromboembolic event can happen at any time. 
     When a thrombus forms in the venous circulation of the body it often embolizes to the lungs. Such a thrombus typically embolizes from the veins of the legs, pelvis, or inferior vena cava and travels to the right heart cavities and then into the pulmonary arteries thus resulting in a pulmonary embolism. 
     A pulmonary embolism results in right heart failure and decreased blood flow through the lungs with subsequent decreased oxygenation of the lungs, heart and the rest of the body. More specifically, when such a thrombus enters the pulmonary arteries, obstruction and spasm of the different arteries of the lung occurs which further decreases blood flow and gaseous exchange through the lung tissue resulting in pulmonary edema. All of these factors decrease the oxygen in the blood in the left heart. As a result, the oxygenated blood supplied by the coronary arteries to the musculature of both the left and right heart is insufficient for proper contractions of the muscle which further decreases the entire oxygenated blood flow to the rest of the body. This often leads to heart dysfunction and specifically right ventricle dysfunction. 
     This condition is relatively common and has many causes. Some of the more common causes are prolonged inactivity such as bed rest, extended sitting (e.g., lengthy aircraft travel), dehydration, extensive surgery or protracted disease. Almost all of these causes are characterized by the blood of the inferior peripheral major circulatory system coagulating to varying degrees and resulting in permanent drainage problems. 
     There exist a number of approaches to treating thromboembolism and particularly pulmonary embolism. Some of those approaches include the use of anticoagulants, thrombolytics and endovascular attempts at removal of the emboli from the pulmonary artery. The endovascular attempts often rely on catheterization of the affected vessels and application of chemical or mechanical agents or both to disintegrate the clot. Invasive surgical intervention in which the emboli is removed by accessing the chest cavity, opening the embolized pulmonary artery and/or its branches and removing the clot is also possible. 
     The prior approaches to treatment, however, are lacking. For example, the use of agents such as anticoagulants and/or thrombolytics to reduce or remove a pulmonary embolism typically takes a prolonged period of time, e.g., hours and even days, before the treatment is effective. In some instances, such agents can cause hemorrhage in a patient. Moreover, the known mechanical devices for removing an embolism are typically highly complex, prone to cause undue trauma to the vessel, and can be difficult and expensive to manufacture. 
     Lastly, the known treatment methods do not emphasize sufficiently the goal of urgently restoring blood flow through the thrombus once the thrombus has been identified. In other words, the known methods focus primarily and firstly on overall clot reduction and removal instead of first focusing on relief of the acute blockage condition followed then by the goal of clot reduction and removal. Hence, known methods are not providing optimal patient care, particularly as such care relates to treatment of a pulmonary embolism. 
     SUMMARY 
     In view of the foregoing, several embodiments of the present technology to provide a method and system that initially restores an acceptable level of oxygenated blood to the patient&#39;s circulatory system followed by safe and effective removal of the thrombus. 
     Several embodiments of the present technology treat pulmonary embolism in a minimally invasive manner. 
     Several embodiments of the present technology can also provide a system that does not cause undue trauma to the vessel. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       These and other objects, aspects, features and advantages of which the present technology is capable will be apparent from the following description of embodiments of the present technology, reference being made to the accompanying drawings, in which 
         FIG.  1 A  is a schematic view of a patient with a pulmonary embolism; 
         FIG.  1 B  is an enlarged view of the lung area of the patient depicted in  FIG.  1 A ; 
         FIG.  1 C  is an enlarged view of the introducer device depicted being used in the femoral vein of the patient in  FIG.  1 A ; 
         FIG.  2    is a cross-sectional view of a patient&#39;s heart; 
         FIG.  3    is a perspective view of a patient&#39;s main pulmonary artery and right and left pulmonary arteries with a clot located in the left pulmonary artery; 
         FIG.  4    is a cross-sectional view of an embodiment of a clot treatment device in accordance with the present technology in a compressed, undeployed state; 
         FIG.  5 A  is a side cross-sectional view of a clot treatment device in a compressed, undeployed state within a delivery catheter in accordance with the present technology; 
         FIG.  58    is a top view of a clot treatment device in a deployed state in accordance with the present technology; 
         FIGS.  6 A- 6 F  are a series of cross-sectional views of embodiments of the method and device of the present technology; 
         FIGS.  7 A- 7 B  are a series of cross-sectional views of embodiments of the method and device of the present technology; 
         FIG.  8    is a cross-sectional view of another embodiment of the method and device of the present technology; and, 
         FIGS.  9 A- 9 H  show cross-sectional views of embodiments of a clot treatment device in accordance with the present technology. 
         FIG.  10    is a cross-sectional view of a clot treatment device in accordance with another embodiment of the present technology. 
         FIGS.  11  and  12    are detailed cross-sectional views of a distal portion and a proximal portion, respectively, of an expandable member of a clot treatment device in accordance with an embodiment of the present technology. 
         FIGS.  13  and  14    are detailed cross-sectional views of a proximal portion and a distal portion, respectively, of an expandable member of a clot treatment device in accordance with another embodiment of the technology. 
         FIGS.  15 - 18    are side views of guide catheters for use with clot treatment devices and methods in accordance with embodiments of the present technology. 
         FIG.  19    is a side view of a clot treatment device including arcuate clot engagement members configured in accordance with an embodiment of the present technology. 
         FIGS.  20 - 23    show embodiments of arcuate clot engagement members configured in accordance with the present technology. 
         FIGS.  24 - 25    are side views of clot treatment devices configured in accordance with embodiments of the present technology. 
         FIG.  26    is a circumferential structure including arcuate clot engagement members in accordance with embodiments of the present technology. 
         FIG.  27    is a side view of a clot treatment device having a distal radially extending member configured in accordance with another embodiment of the present technology. 
     
    
    
     DETAILED DESCRIPTION 
     Specific embodiments of the present technology will now be described with reference to the accompanying drawings. This present technology may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the present technology to those skilled in the art. The terminology used in the detailed description of the embodiments illustrated in the accompanying drawings is not intended to be limiting of the present technology. In the drawings, like numbers refer to like elements. 
     Referring to  FIGS.  1 A- 1 C , these drawings show the typical locations in a human patient where clots  100 , such as pulmonary embolisms, thromboses, or other obstructions, occur in the pulmonary arteries and further discloses the pathway through which access to such clots  100  is achieved. In particular, an introducer device (e.g., a hemostatic valve)  102  which supports relatively large diameter devices is inserted into the patient into the femoral vein FV in the pelvic area of the patient. The tools and devices needed to treat the pulmonary embolism are then inserted through the introducer  102  into the femoral vein FV through the inferior vena cava IVC to the patient&#39;s heart. 
     It will be understood, however, that other access locations into the venous circulatory system of a patient are possible and which are consistent with the present technology. For example, the user can gain access through the jugular vein, the subclavian vein, the brachial vein or any other vein that connects or eventually leads to the superior vena cava. Use of other vessels that are closer to right atrium RA of the patient&#39;s heart may be attractive as this will reduce the length of the instruments needed to reach the pulmonary embolism. 
     Referring to  FIGS.  2  and  3   , the tools/devices are then guided through the right atrium RA through the tricuspid valve TV, into the right ventricle RV, through the pulmonary valve PV into the main pulmonary artery (MPA). Depending on the location of the embolism  100 , the tools/devices are then guided to one or more of the branches of the right pulmonary artery RPA or the left pulmonary artery LPA, including deeper branches thereof, to the location of the pulmonary embolism  100 . 
     Referring to  FIG.  4   , an embodiment of a clot treatment device  402  for restoring blood flow through the clot  100  and for removing at least a portion of the clot is depicted in its undeployed, or compressed state. The device  402  is constrained by a delivery catheter  606 . In many embodiments, the device  402  comprises a braided material having ends that are captured distally by a tip  405  and proximally by an attachment member  403  that connects to a wire  401  configured to push and/or pull the clot treatment device  402 . 
     In alternative embodiments, the clot treatment device  402  may be an “over the wire” device, in which case, the wire  401  is a tube or coil having a lumen, and the attachment member  403  and the tip  405  have a hollow central lumen for receiving a guide wire. 
     In yet a further embodiment, the distal end of the clot treatment device shall have a flexible, atraumatic extension from the device. In an alternative embodiment, the tip  405  is tapered to better penetrate the clot material in the vessel. 
     In preferred embodiments the clot treatment device  402  of the present technology has a generally cylindrical shape that, during use, creates a flow lumen through the clot material that restores significant blood flow across a clot. The treatment device  402  is not, however, limited to a generally cylindrical shape. For example, the shape can be generally conical, generally concave or generally convex along its axis such that the clot treatment device  402  creates a lumen for restoring the blood flow. 
       FIG.  5 A  shows one embodiment of the treatment device  402  in a low-profile, undeployed state in which the clot treatment device is configured to fit within a delivery catheter, and  FIG.  58    shows the clot treatment device  402  of  FIG.  5 A  in a deployed state configured to restore blood flow and capture clot material for removal. Referring to  FIG.  5 A , the clot treatment device  402  is compressed to fit within the diameter OL of a lumen  607  of the delivery catheter  606  in the undeployed state. In the deployed state shown in  FIG.  58   , the clot treatment device  402  has a plurality of capture elements, such as a series of radially extending capture portions  406  which are separated from each other by flow restoration portions  412 . The flow restoration portions  412  are configured to expand outwardly from the low-profile undeployed state within the delivery catheter lumen  607  to a first cross-sectional dimension  01  (e.g., diameter) in the deployed state. For example, the flow restoration portions  412  can be generally cylindrical braided sections that expand radially outward from the undeployed stated to the deployed state. In many applications, the first cross-sectional dimension  01  is greater than the diameter OL of the delivery catheter lumen  607 . The capture portions  406  are configured to expand outwardly from the low-profile undeployed state to a second cross-sectional dimension  02  greater than the first cross-sectional dimension  01  in the deployed state. As explained in more detail below, the capture portions  406  can project into the clot such that they extend transverse to a longitudinal axis L-L of the clot treatment device  402 , while the flow restoration portions  412  expand radially outward into the clot to open a passage through which blood can quickly resume flow through the vessel. The clot treatment device  402  can be porous so blood flows therethrough. In this regard, many embodiments of the clot treatment device  402  are made from a mesh or braided material. The material can be a super-elastic material such as Nitinol or an alternative material such as cobalt chrome alloy. The device can be made from a wire lattice, wire braid or stent. Specific preferred embodiments are discussed throughout this specification. 
     Referring again to  FIG.  58   , the clot treatment device  402  can comprise a single mesh structure that is generally cylindrical in the low-profile undeployed state (shown in  FIG.  5 A ). The series of radially extending capture portions  406  accordingly extend from the same mesh as the corresponding series of flow restoration portions  412 . The flow restoration portions  412  can be generally cylindrical sections in the deployed state, or in other embodiments the flow restoration portions  412  may taper in the distal direction individually and/or collectively to form a conical lumen (not shown). Each of the capture portions  406  can be a radial or otherwise transversely projecting disk that projects outward relative to the flow restoration portions  412 . 
     The clot treatment device  402  can self-expand from the undeployed state to the deployed state. For example, the clot treatment device  402  can be a shape-memory material, such as Nitinol, and may be formed as a braid or a stent that is set to have the expanded configuration of the deployed state shown in  FIG.  58    unless it is otherwise deformed or constrained, such as being elongated along the longitudinal axis L-L to fit within the delivery catheter  606  as shown in  FIG.  5 A . In other embodiments, the clot treatment device  402  can be actuated by a push/pull wire, tube or coil to move from the low-profile undeployed state to the expanded deployed state as explained in more detail below with reference to  FIGS.  10 - 12   . 
       FIGS.  1 - 6 F  show embodiments of methods for restoring blood flow and retrieving/removing clot material with the clot treatment device  402  in a body lumen L. 
     Referring to  FIGS.  1 A,  1 B and  6 A , a guide wire  602  is inserted into the patient via an introducer  102  and maneuvered through the femoral vein FV into the inferior vena cava IVC to the heart. As stated above, access can also be achieved through one of the veins leading to the superior vena cava SVC. The guide wire  602  is then urged through the right atrium RA, through the tricuspid valve TV, through the right ventricle RV, through the pulmonary valve PV to the main pulmonary artery MPA and then to a location of the clot  100  in one of the branches or lumens L of either the right or left pulmonary artery RPA, LPA. In several embodiments, the guide wire  602  is extended through the clot  100  in the body lumen Las shown in  FIG.  6 A . 
     Referring to  FIG.  68   , a guide catheter  604  is placed over the guide wire  602  and moved to a location where a distal end of the guide catheter  604  is positioned proximal to the clot  100 . At this point, the guide wire can optionally be withdrawn. However, in the embodiment shown in  FIG.  6 C , the guide wire  602  remains positioned through the clot  100  and a delivery catheter  606  is then moved through the. guide catheter  604  over the guide wire  602  and pushed through the clot  100 . 
     Referring to  FIG.  60   , the guide wire  602  is then withdrawn and the clot treatment device  402  in its undeployed (i.e., compressed) state is then moved through the delivery catheter  606  until it is positioned at the distal end of the delivery catheter  606 . Alternatively, if an over-the-wire device configuration (as shown in  FIG.  10   ) is used, the guide wire  602  may be left in place while the treatment device  402  is deployed and retracted. Referring to  FIG.  6 E , the delivery catheter  606  is then retracted in a proximal direction while maintaining forward pressure on the clot retrieval device  402  via the pusher wire  401  so that the clot treatment device  402  is exposed and released from the delivery catheter  606 . The clot treatment device  402  radially expands into the clot  100  and, in some embodiments, at least a portion of the clot treatment device  402  expands distal of the clot  100 . For example, at least one of the radially extending capture portions  406  of the clot treatment device  402  is located distal to the clot  100  upon expansion of the clot treatment device  402 . Additionally, the flow restoration portions  412  between the capture portions  406  also expand outwardly against a portion of the clot  100  to form a flow passage  430  though the clot treatment device  402 . 
     The clot treatment device  402  accordingly restores blood flow through the clot  100  immediately or at least quickly after expanding to the deployed state as shown by arrows  407  in  FIG.  6 E . More specifically, the blood freely moves through the mesh of the clot treatment device  402 , travels through the device lumen and exits the clot treatment device  402  distal to the clot  100 . As a result, the acute condition of blockage is mediated thus immediately improving the circulation of oxygenated blood in the patient. 
     The restoration of blood flow is anticipated to equate with restoration of a substantial portion of the normal blood flow rate for the patient. In less severe. e.g., “sub-massive,” pulmonary embolism patients, the clot treatment device  402  may increase blood flow rate by at least about 50 ml|min, at least about 150 ml|min or between about 100 to 250 ml|min. In severe, e.g., “massive,” pulmonary embolism patients, a larger amount of the pulmonary artery flow is compromised. Hence, in some embodiments, at least about 500 ml/min of blood flow rate may be restored. Moreover, at least a portion of the flow restoration is expected to occur prior to the removal of the clot  100 , or any portion thereof. 
     The restoration of blood flow by the clot treatment device  402  can be achieved in a low pressure environment. For example, the pressure in the target vessel can be less than 60 mmHg and the blood can be venous blood, substantially non-oxygenated blood or low oxygenated blood. 
     In addition to restoring blood flow, the expansion of the clot treatment device  402  also deforms the clot material by pushing, penetrating and/or otherwise cutting into the clot material. This enhances the subsequent removal of the clot  100  since portions of the clot  100  may be captured and retained (1) between the radially extending portions  406 ; (2) through the pores of the mesh forming the radially extending portions  406 ; (3) along the longitudinal cylindrical sections  412  between the radially extending portions  406  of the removal device  402 ; and (4) within the clot treatment device  402  itself. 
     As can be understood from the above description and figures, the deployment of the clot treatment device  402  results in an outwardly expanding generally cylindrical force being urged against an inner surface of the clot  100  because the flow restoration portions  412  expand to the first cross-sectional dimension D 1  greater than the diameter DL of the delivery catheter lumen  607 . This force pushes the clot material outwardly and creates a lumen through which blood flow is restored. As can also be appreciated, the presence of the radially extending capture portions  406  on the clot treatment device  402  causes the outwardly expanding generally cylindrical force to vary in magnitude along the axis of the clot treatment device  402 . The force on the clot material may be greater at the locations of the radially extending capture portions  406 . 
     In braided embodiments of the clot treatment device  402 , deployment/expansion of the device leads the filaments of the braid to change their angular orientation with respect to the axis of the device. This angular change may improve or enhance adherence of clot material to the clot treatment device  402 . 
     After the clot treatment device  402  has been expanded and blood flow restored, the user then retracts the clot treatment device  402  in a proximal direction as shown in  FIG.  6 F . Sinethe capture portions  406  extend transverse to the longitudinal dimension of the vessel, the capture portions  406  form transverse surfaces relative to the force exerted against the clot  100  as the clot treatment device  402  is pulled in the proximal direction. The capture portions  406  accordingly enhance the ability of the clot treatment device  402  to securely dislodge and retain the clot  100  as the clot treatment device  402  is moved axially along the vessel to retrieve the clot  100  from the patient. In one embodiment, the clot treatment device  402  and the delivery catheter  606  are pulled back simultaneously into the guide catheter  604 . This is followed by the entire apparatus (e.g., clot treatment device  402 , delivery catheter  606  and guide catheter  604 ) being withdrawn through the heart and the venous circulation and out from the body. 
     As further shown in  FIG.  6 F , the clot treatment device  402  may elongate as it is being withdrawn into the guide catheter  604  due to the resistance it encounters from the presence of clot material of the clot  100 . The presence of the radially extending portions  406  may allow elongation that enhances the capability of the device  402  to capture the maximum amount of clot material. This is further discussed below with respect to the surface area and expansion ratio of preferred embodiments of the clot treatment device  402 . 
     It will be appreciated that variations in the above-described method are contemplated. For example, in certain circumstances a guide catheter  604  may not be necessary or desirable and the user may choose to use only the delivery catheter  606  for placing and manipulation of the clot treatment device  402 . As a further example, the clot may be of such a nature that the user may desire repeat the above-described process, or at least portions of it, in order to more fully remove the clot  100  or clot material. 
     Referring next to  FIGS.  7 A- 78   , it may be advantageous to include the use of a collection or funnel catheter  612  to assist in the removal of the clot  100 . Such a funnel catheter  612  has an expandable portion  614  at its distal end and may be situated between the guide catheter  604  and the delivery catheter  608  or may be part of the guide catheter  604 . In the presence of the collection catheter  612 , the clot treatment device  402  is pulled proximally into the collection catheter  612  such that the clot or portions of it are captured within the collection catheter  612 . In an alternative embodiment, the collection catheter  612  can be pushed distally over the clot treatment device  402  such that the collection catheter  612  captures the clot or portions thereof. If the collection catheter  612  is separate from the guide catheter  606 , the collection catheter with the clot treatment device  402  is then pulled into the guide catheter for ultimate removal of all devices (and the clot) from the patient. 
     In certain circumstances, it may be advisable to remove the clot  100  without capturing it in the guide catheter  606  or the collection catheter  612  (if used) and remove the clot  100  by withdrawing the entire system, e.g., guide catheter  605 , delivery catheter  604 , clot treatment device  402  and collection catheter  612  (if used) simultaneously. 
     In several embodiments, the expandable portion  614  of the collection catheter  612  is a conical funnel or other tapered member constructed from a mesh, braid or stent structure. Such structure assists in retrieving and containing the clot material in the withdrawal process. In yet further preferred embodiments, the collection catheter  612  contains structural features to assist in the expansion of the expandable portion  614  and to hold the expandable portion  614  open towards the wall of the blood vessel. Such features (not shown) include interwoven support struts, self expanding material (e.g., Nitinol), longitudinal wire supports, stent supports, polymeric webbing, etc. 
     In another embodiment of the present invention, a vacuum apparatus may be used to aid in the removal of the clot material. Referring to  FIG.  8   , a syringe  802  is shown connected to a vacuum manifold  806  that is in fluid communication with the proximal end of the guide catheter  604 . At the time the clot treatment device  402  (and clot material) is being withdrawn into the guide catheter  604  (or the collection catheter  612 ), vacuum is applied by pulling on the syringe. Alternative sources of vacuum  804  are also acceptable, e.g., a vacuum pump. A system is also contemplated whereby vacuum is actuated automatically when the clot treatment device  402  (and the clot material) is being withdrawn. A representation of the effect of the use of vacuum can be seen with reference to  FIG.  78    which shows how vacuum causes flow  701  into the catheter  612 . 
     Referring now to  FIGS.  9 A- 9 H , alternative preferred embodiments of the clot treatment device  402  are disclosed. 
     Referring to  FIG.  9 A , the radially extending portions  406  between the generally cylindrical sections  412  of the clot treatment device  402  are defined by a cylindrical disk shape with a rounded triangular cross-section. 
     Referring to  FIG.  98   , the radially extending portions  406  between the generally cylindrical sections  412  of the clot treatment device  402  are defined by a cylindrical disk shape with a rounded triangular cross-section wherein the diameter of the disk increases along the length of the device  402  thus forming a conical exterior extent. 
     Referring to  FIG.  9 C , the radially extending portions  406  between the generally cylindrical sections  412  of the clot treatment device  402  are defined by a cylindrical disk shape with a rectangular cross-section. 
     Referring to  FIG.  90   , the radially extending portions  406  between the generally cylindrical sections  412  of the clot treatment device  402  are defined by a cylindrical disk shape with a linear (non-rounded) triangular cross-section. 
     Referring to  FIG.  9 E , some of the radially extending portions  406  between the generally cylindrical sections  412  of the clot treatment device  402  are defined by a cylindrical disk shape with a rounded cross-section and others have a rectangular cross section. 
     Referring to  FIG.  9 F , the radially extending portions  406  between the generally cylindrical sections  412  of the clot treatment device  402  alternate between cylindrical disk shape with a T-shaped cross-section and a flare-shaped cross-section. 
     Referring to  FIG.  9 G , the radially extending portions  406  between the generally cylindrical sections  412  of the clot treatment device  402  are defined by a partial cylindrical disk shapes. 
     Referring to  FIG.  9 H , the radially extending portions  406  between the generally cylindrical sections  412  of the clot treatment device  402  are defined by tabs and bumps or protuberances arising from the cylindrical surface of the device  402 . 
       FIG.  10    is a cross-sectional view of another embodiment of the clot treatment device  402  in accordance with the technology having an expandable member  1010 , an elongated inner member  1020 , and an elongated outer member  1022 . The expandable member  1010  is configured to have an undeployed state in which the expandable member  1010  is elongated axially to have a low profile that fits within a delivery catheter as shown in  FIG.  4   . The expandable member  1010  is further configurable into a deployed state in which the expandable member  1010  forms a flow channel  1012  for restoring blood flow through the region obstructed by the clot. The expandable member  1010 , for example, can be a mesh, braid, stent-type device, or other suitable member through which blood flows in the deployed state. In one embodiment, the expandable member  1010  is a continuous braid formed from a shape-memory material that has been heat set such that, in the deployed state, the expandable member  1010  has a plurality of flow restoration portions  412  that expand to the first cross-sectional dimension  01  to form the flow channel  1012  and a plurality of capture portions  406  that expand to the second cross-section dimension  02  greater than the first cross-sectional dimension  01 . The flow restoration members  412  accordingly exert an outward force (arrows  0 ) against clot material (not shown) to create the flow channel  1012 , and the capture portions  406  accordingly exert a longitudinal force L (arrows L) against the clot material as the clot treatment device  402  is moved proximally. 
     The elongated inner member  1020  can be a tube or coil having inner lumen configured to receive the guidewire  602  for over-the-wire or rapid exchange delivery of the expandable member  1010  to the clot. The outer elongated member  1022  can be a tube or coil having a lumen configured to receive the inner elongated member  1020  such that the inner elongated member  1020  and/or the outer elongated member  1022  can move relative to each other along the longitudinal dimension of the clot treatment device  402 . 
       FIGS.  11  and  12    are detailed views of a distal portion  1011   a  ( FIG.  11   ) and a proximal portion  1011   b  ( FIG.  12   ) of the expandable member  1010  of the clot treatment device  402  shown in  FIG.  10   . Referring to  FIG.  11   , the distal portion  1011   a  is attached to a distal end of the inner elongated member  1020  by the tip  405 . The tip  405  can be blunt as described above with reference to the embodiment of the clot treatment device  402  shown in  FIG.  4   , or the tip  405  can have a tapered distal portion  1040  configured to pass through the clot as shown in  FIG.  11   . Additionally, the tip  405  can have a proximal opening  1042  configured to receive the distal end of the inner elongated member  1020  and the distal end of the expandable member  1010 . Referring to  FIG.  12   , the proximal portion  1011   b  is attached to the distal end of the outer elongated member  1022  by a proximal hub  1030 . For example, the distal and proximal portions  1011   a  and  1011   b  can be attached to the inner elongated member  1020  and the outer elongated member  1022 , respectively, using welds, adhesives, crimping or clamping forces, and/or other suitable attachment mechanisms. 
     In the operation of the clot treatment device  402  shown in  FIGS.  10 - 12   , the expandable member  1010  can self-expand from the undeployed state to the deployed state without an actuator. For example, as a delivery catheter is drawn proximally to release the expandable member  1010 , the inner elongated member  1020  can be held in place to hold the distal portion  1011   a  of the expandable member  1010  distally of the clot. As the distal end of the delivery catheter moves proximally, the outer elongated member  1022  will slide distally as the expandable member  1010  expands until the expandable member  1010  reaches its predetermined deployed size or otherwise reaches equilibrium with the clot. In other embodiments, the inner elongated member  1020  and/or the outer elongated member  1022  can be actuators that are moved proximally and/or distally to control the radial expansion and/or the radial contraction of the expandable member  1010 . 
       FIGS.  13  and  14    are detailed views of the proximal and distal portions  1011   b  and  1011   a , respectively, of an expandable member  1010  and other components of a clot treatment device  402  in accordance with another embodiment of the technology. In this embodiment, the clot treatment device  402  has a proximal tube  1410  ( FIG.  13   ) and an expansion element  1420  having one end attached to the proximal tube  1410  and another end attached to the distal portion  1011   a  ( FIG.  14   ) of the expandable member  1010 . The expansion element  1420 , for example, can be a coil or spring that is stretched from its normal state when the expandable member  1010  is the low-profile, undeployed state inside the delivery catheter. As the distal portion  1011   a  and then the proximal portion  1011   b  of the expandable member  1010  are released from the delivery catheter, the expansion element  1420  contracts axially under its own stored spring force causing the expandable member  1010  to contract axially and expand radially outward. In the embodiments where the expandable member  1010  is self-expanding, the expansion element  1420  assists the expansion of the expandable member  1010 . In other embodiments, the expandable member  1010  may not be self-expanding or may be inherently spring-biased into the low-profile undeployed state, and the expansion element  1420  can have enough stored energy when it is stretched in the low-profile undeployed state to pull the distal portion  1011   a  and the proximal portion  1011   b  of the expandable member  1010  toward each other and thereby radially expand the expandable member  1010 . 
     In the foregoing embodiments, the radially extending capture portions  406  provide more surface area along the device than a device that is uniformly cylindrical. Moreover, the radially extending capture portions  406  extend transversely to the longitudinal dimension of the device to more effectively transfer the axial force as the device is moved axially along the vessel after deployment. Such increased surface area facilitates the treatment and/or retrieval of a much larger portion of the clot  100  than is generally feasible with a uniformly cylindrical device. For example, in a preferred embodiment of the clot treatment device  402 , the device will have an external surface area between 1.5× and 6× the surface area of a uniformly cylindrical device of the same general diameter of the cylindrical sections  412 . In other preferred embodiments the ratio will be 2× to 4×. 
     This is advantageous particularly during retraction of the clot treatment device  402  through the clot  100 . As shown in  FIG.  6 F , the clot treatment device  402  may become elongated as it is being withdrawn through the clot  100 . Such elongation causes the clot material to encounter greater surface area of the clot treatment device  402  than would otherwise occur with a device that was only generally cylindrical, i.e., that did not incorporate radially extending portions  406 . Accordingly the clot treatment device  402  is particularly adept at capturing the maximum amount of clot material during withdrawal. 
     The clot treatment device  402  is intended for use in large vessels, i.e., vessels with a diameter greater than 8 mm. For example, the diameter of the pulmonary arteries typically range from 15 to 30 mm whereas the first branches of the pulmonary arteries typically range from 10 to 15 mm and the secondary and tertiary branches typically range from 5 to 10 mm. At the same time, however, it is important to minimize the size of catheter providing access to the clot  100 . Accordingly, the clot treatment device  402  has a large expansion ratio. In a preferred embodiment the expansion ratio from the diameter of the cylindrical sections  412  in the collapsed state to the expanded state will be between 4 and 8. In another preferred embodiment the ratio will be between 5 and 7. The large expansion ratio also enables the formation of a flow channel in the clot  100  that is large, e.g., on the order of 4-8 mm. 
     The radially extending portions  406 , in their fully expanded position are intended to have a size that matches the diameter of the target blood vessel. However, the diameters may be slightly larger than the vessel diameter so to apply greater radial force against the blood vessel (without causing trauma) in those circumstances when it is desirable to improve clot collection. Similarly, in those circumstances where there is a concern of creating trauma on delicate blood vessels, the radially extending portions  406  may have a diameter that is smaller than the vessel diameter. It is contemplated that different sizes of the device  402  will be available for selection by the user for a particular presentation of the patient. 
     As for the length of the clot treatment device  402 , it is known that a typical pulmonary embolism will have a length within the range between about 2 em and 10 em and sometimes between about 1 em and 20 em. Accordingly, in a preferred embodiment, the clot treatment device  402  will have a length that exceeds the length of the embolism so that a portion of the clot treatment device is positioned distal of the clot  100  during expansion. 
     With regard to the delivery catheter  606 , in a preferred embodiment for use with a pulmonary embolism, the size will be around 1 F-6 F. Smaller diameters will pass through the clot  100  more easily. In addition, the delivery catheter  606  may have stiffness characteristics to assist in making sure the delivery catheter  606  passes through the clot in a smooth manner. Such stiffness characteristics include self expanding Nitinol wire braids or stent structures that are contained within the structure of the delivery catheter  606 . The delivery catheter  606  also has sufficient flexibility so that it may carry the clot treatment device  402  and still pass through a tortuous vessel path as described above starting with insertion of the delivery catheter  606  in the femoral vein FV. 
     In some preferred embodiments, the method and device in accordance with the present invention may reduce the Mean Resting Pulmonary Artery Pressure (MRPAP). Upon at least partial relief from the clot  100 , MRPAP may be reduced by about 20-50 mmHg to a normal range of 8-20 mmHg. In some embodiments, the reduction in MRPAP may be about 25-50%. In some embodiments, the reduction in MRPAP may be about 15% to 40% and in other embodiments between about 30% and 75%. 
     Such a reduction in MRPAP can occur in two steps. A first step is when the clot treatment device  402  is first deployed and blood flow is at least partially restored. A second step may be when the clot treatment device  402  is retracted and at least some of the clot  100  is removed from the vessel. A third step may be after the clot treatment device  402  has been removed and the effect of the body&#39;s own processes and/or thrombolytic drugs that may have been used before, during or after the procedure take effect upon clot that has been disrupted by the clot treatment device. 
       FIG.  15    is a side view of an embodiment of a guide catheter  1500  for use with any of the foregoing embodiments of the clot treatment devices  402  (not shown in  FIG.  15   ). The guide catheter  1500  can include a shaft  1502  having a sufficiently large lumen to accommodate the delivery catheter  606  ( FIGS.  4  and  5 A ). The guide catheter  1500  can further include an expandable guide member  1510  at the distal end of the shaft  1502  configured to expand radially outward to contact or nearly contact the vessel wall VW. The guide member can be formed from a permeable, radially expanding material, such as a mesh or other macroporous structure (e.g., a braid of wires or filaments). The guide member  1510 , for example, may be formed from a tubular braid of elastic or super-elastic filaments such as Nitinol that has been heat set into the desired expanded shape. The permeable, radially expanding guide member  1510  may have advantages over an occlusive member such as a balloon or impermeable funnel. For example, the guide member  1510  allows a substantial amount of blood flow BF to continue flowing through the blood vessel where therapy is being directed. In addition, the guide member  1510  positions the shaft  1502  and delivery catheter  606  at or near the center of the vessel. The clot treatment device  402  (not shown in  FIG.  15   ) may also be substantially self-centering upon deployment, and the guide member  1510  may further guide the clot material captured by the clot treatment device  402  into the shaft  1502  as the clot treatment device  402  moves into proximity of the distal end of the shaft  1502 . This is expected to enhance aspiration of the clot material. For example, in the embodiment shown in  FIG.  15   , the radially expanding guide member  1510  has a funnel shape adjacent the distal end of the shaft  1502  to guide thrombus material into the distal opening of the shaft  1502  where it can be more readily aspirated. 
     The radially expanding guide member  1510  may also be formed by conventional machining, laser cutting, electrical discharge machining (EDM) or other means known in the art to make a fenestrated, mesh or porous structure that can be affixed near the distal end of the shaft  1502 . In some embodiments the radially expanding guide member  1510  may self-expand, but in other embodiments it may be actuated by an operator using, for example, electrical or electromechanical means. By having a porous radially expanding guide member  1510 , the guide catheter  1500  may be substantially centered within a vessel without blocking a large portion of the flow around the catheter. In some embodiments, the radially expanding guide member  1510  may block less than about 50% of the flow about the catheter and in other embodiments less than about 25% of the flow. When the guide member  1510  is made with a braid of filaments (e.g. wires), it may be formed from a tubular braid. In some embodiments, the tubular braid may be formed with approximately 12 to approximately 144 filaments, or in other embodiments from about 36 to about 96 filaments. The pores as measured by the largest circle that can be inscribed within an opening of the mesh may be between about 0.5 mm and 5 mm. 
       FIGS.  16  and  17    show additional embodiments of guide members  1610  and  1710 , respectively, that can be used instead of or in addition to the guide member  1510 . Referring to  FIGS.  15  and  16   , one or both ends of the tubular braid of the guide members  1510  and  1610  may be inverted and attached to the catheter body. Referring to  FIG.  17   , neither end of the guide member  1710  is inverted. With the distal end inverted, it advantageously may form a funnel adjacent the distal opening of the catheter that may enhance clot capture and aspiration. 
       FIG.  18    shows an embodiment of a guide catheter  1900  having a shaft  1902  and a guide member  1910  in accordance with another embodiment of the technology. In the embodiment shown in  FIG.  18   , the guide member  1910  has a tapered or funnel shape, and includes a non-permeable portion  1912  and a permeable portion  1914 . The permeable portion  1914  can comprise a flared radially expanding mesh that has, at least in part, a tapered or funnel shape, and the non-permeable portion  1912  may have a substantially non-porous or otherwise non-permeable material or coating over the mesh. Preferably, the non-permeable material is a highly elastic material such as polyurethane, silicone, latex rubber and the like so that it can flex with the expansion of the mesh. In some embodiments, the non-permeable material covers a proximal portion of the mesh as shown in  FIG.  18   . The non-permeable portion  1912  may divert some flow away from the distal end of the catheter. The covering may cover a portion of the mesh to a diameter “d”. In some embodiments, the diameter d of the covering is less than about 75% of the diameter “D” of the mesh funnel. In some embodiments, the diameter d may be less than about 50% of diameter D. The concept of a non-permeable material can also be applied to the guide catheter  1500  shown above in  FIG.  15   . For example, the expandable member  1510  of the guide catheter  1500  can have a non-permeable portion  1512  at the proximal portion of the expandable guide member  1510  similar to the non-permeable portion  1912  shown and described with reference to  FIG.  18   . 
       FIGS.  19 - 27    show additional embodiments of clot treatment devices  402  in accordance with the present technology. The embodiments of the clot treatment devices  402  shown in  FIGS.  19 - 27    can restore blood flow and capture clot material in a manner similar to the embodiments of the clot treatment devices  402  described above with respect to  FIGS.  4 - 18   . The embodiments of the clot treatment devices  402  related to  FIGS.  19 - 27    can also be made from the same materials and be deployed in the same manner as described above with respect to  FIGS.  4 - 18   . As such, many of the features, materials and benefits of the clot treatment devices  402  shown in  FIGS.  4 - 18    are applicable to the clot treatment devices shown in  FIGS.  19 - 27   . 
       FIG.  19    shows an embodiment of the clot treatment device  402  that includes a plurality of capture elements, such as clot engagement (“CE”) members  1952 . The CE members  1952  can be (a) arcuate as shown in  FIG.  19   , (b) bent at one or more angles (e.g., 30°, 45°, 60°, 90°, 135°, etc.), and/or (c) straight (e.g., project outward along a straight line). In some embodiments, the clot treatment device  402  can include a combination of arcuate, angled and/or straight CE members. In other embodiments, the clot treatment device  402  can include a single CE member  1952 . The CE members  1952  can be interwoven into the mesh structure of the device  402  (see  FIG.  21   ). The CE members  1952  can also be bonded, soldered, welded, tied or otherwise secured to the mesh structure or mechanically interlocked with the mesh structure. As the clot treatment device  402  is unsheathed during deployment, the CE members  1952  can radially extend and form a heat-set shape configured to penetrate and fasten the clot to the treatment device  402 . The CE members  1952  can accordingly define hook-like capture elements in several embodiments of the present technology. 
     The CE members  1952  can be disposed about an exterior surface of the device  402 . For example, as shown in  FIG.  19   , the CE members  1952  can be arranged in one or more circumferential rows  1954  that are evenly positioned along a longitudinal axis of the device  402 . In other embodiments, the CE members  1952  can have any suitable arrangement and/or positioning about the device (e.g., arranged in a helical pattern, off-set rows, random, or irregular or otherwise uneven/non-uniform spacing, etc.). 
     As shown in  FIG.  19   , the CE members  1952  can curve proximally such that a concave portion  1956  of the CE members  1952  face a proximal region  402   b  of the device  402 . In some embodiments, the CE members  1952  can curve distally such that a concave portion of the CE members  1952  face a distal region  402   a  of the device  402  (not shown). In particular embodiments, the clot treatment device  402  includes both distally-curving and proximally-curving CE members. 
     The CE members can have a single radius of curvature or have regions with different radii or have a complex or changing radius of curvature. For example, as shown in  FIG.  20   , one or more of the CE members  1952  can have a first portion  1958  that has a first radius R and a second portion  1960  (e.g., the distal region of the CE member  1952 ) that has a second radius r that is smaller than the first radius R. In some embodiments, the first radius R may range from about 2 mm to about 15 mm, and the second radius r may range from about 0.25 mm to about 5 mm. Additionally, the CE members  1952  can have a range of arc lengths. For example, in some embodiments the CE members  1952  can have an arc length greater than 180 degrees. In certain embodiments, the arc length can be between 180 degrees and 330 degrees. 
       FIG.  22    shows another embodiment of a CE member  2202  having a V-shaped base  2204  that branches into a first arm  2206   a  and a second arm  2206   b . The V-shaped base  2204  and/or any portion of the first and/or second arms  2206   a ,  2206   b  can be interwoven into the mesh structure of the clot treatment device  402 , as shown in  FIGS.  24  and  25   . In some embodiments, the angle a between the first and second arms  2206   a ,  2206   b  may be between about 40 degrees and about 100 degrees. Although  FIG.  24    shows a plurality of such CE members  2202  disposed about a clot treatment device  402 , in other embodiments the device  402  can only include a single CE member  2202 . 
     As shown in  FIG.  25   , the first arm  2206   a  and the second arm  2206   b  can extend into a first distal portion  2208   a  and a second distal portion  2208   b , respectively, where the first distal portion  2208   a  and the second distal portion  2208   b  are generally arcuate. As shown in  FIG.  24   , in some embodiments the first distal portion  2208   a  and the second distal portion  2208   b  can be generally linear. 
     Referring to  FIG.  26   , two or more CE members can be connected to form a circumferential structure  2602  that extends around at least a portion of a circumference of a clot treatment device  402 . The device  402  can include one or more circumferential structures  2602  spaced along a longitudinal axis of the device. These circumferential structures  2602  can allow for the CE members to flex with the mesh structure as it expands and contracts. In some embodiments, the angle  8  formed by the circumferential structure  2602  can be between about 40 degrees and about 100 degrees. 
       FIG.  23    shows one embodiment of an CE member  2302  having a double-wire arcuate portion  2306 . Referring to  FIG.  27   , in some embodiments, the clot treatment device  402  can include a plurality of CE member  1952  and a radially extended member  406  at a distal end. The radially extended member  406  could be a disc, balloon, screen or other clot capture member. 
     EXAMPLES 
     Several examples of the present technology are as follows: 
     1. A device for treating a pulmonary embolism, comprising:
         an expandable flow restoration portion; and   a plurality of capture elements including at least a first capture element and a second capture element, wherein the flow restoration portion is between the first and second capture elements, and wherein the flow restoration portion and the capture elements are configured to move from a low-profile undeployed state sized to fit within a delivery catheter to a deployed state in which the flow restoration portion has a first cross-sectional dimension greater than that of the low-profile state such that the flow restoration portion forms a flow channel through the device and the capture elements project outwardly from the flow restoration portion.       

     2. The device of example 1 wherein the flow restoration portion and the capture elements comprise an expandable braided material that is heat set to have the deployed state. 
     3. The device of any of examples 1 and 2 wherein the flow restoration portion and the capture elements are integrally formed from a common braided material. 
     4. The device of any of examples 1-3, further comprising a plurality of flow restoration portions and the capture elements comprise a series of radially extending capture portions, and wherein the radially extending capture portions are separated from each other by individual flow restoration portions. 
     5. The device of example 4 wherein the flow restoration portions comprise expandable cylindrical sections and the capture elements comprise radially expandable disk-like capture portions of the braided material. 
     6. The device of example 1 wherein the flow restoration portion comprises a radially expandable cylindrical braided material and the capture elements comprise protuberances projecting from the flow restoration portion. 
     7. The device of any of examples 1-6 wherein the flow restoration portion has an expansion ratio from the undeployed state to the deployed state of approximately 1:4 to 1.8. 
     8. The device of any of examples 1-6 wherein the flow restoration portion has an expansion ratio from the undeployed state to the deployed state of approximately 1:5 to 1.7. 
     9. The device of any of examples 1-8 wherein the flow restoration portion has a diameter of approximately 4-8 mm in the deployed state to restore blood flow through a pulmonary embolism. 
     10. The device of any of examples 1-9 wherein the flow restoration portions and the capture elements comprises a self-expanding braided material, and the capture elements comprise capture portions that have a second diameter greater than the first cross-sectional dimension of the flow restoration portions in the deployed state. 
     11. The device of any of examples 1-3 and 6-9 wherein the flow restoration portion comprises a single expandable braided tube, and the capture elements comprise clot engagement members configured to project from the flow restoration portion in the deployed state. 
     12. The device of example 11 wherein the clot engagement members comprise arcuate members that form hook-like elements projecting from the flow restoration portion. 
     13. The device of example 11 wherein the clot engagement members are formed from wires of the expandable braided tube that defines the flow restoration portion. 
     14. The device of example 11 wherein the clot engagement members are formed from separate wires that project through interstices of the expandable braided tube that defines the flow restoration portion. 
     15. A pulmonary embolism treatment device, comprising:
         an outer elongated member having a distal end;   an inner elongated member within the outer elongated member, wherein the inner elongated member and/or the outer elongated member slides relative to the other, and wherein the inner elongated member has a distal end; and   an expandable member having a proximal portion attached to the distal end of the outer elongated member and a distal portion attached to the distal end of the inner elongated member, the expandable member having a flow restoration portion and a plurality of capture elements arranged along the flow restoration portion, wherein the flow restoration portion and the capture elements are configured to move from a low-profile undeployed state sized to fit within a delivery catheter to a deployed state in which the flow restoration portion has a first cross-sectional dimension greater than that of the low-profile state that defines a flow channel through the device and the capture elements project outwardly from the flow restoration portion.       

     16. The pulmonary embolism treatment device of example 15 wherein the expandable member comprises a braided material. 
     17. The pulmonary embolism treatment device of example 15 wherein the device has a plurality of flow restoration portions and the capture elements are separated by individual flow restoration portions, and wherein (a) the capture elements comprise capture portions formed from a continuous shape-memory braided material heat-set to the deployed state and (b) the capture portions project from the flow restoration portions to a second cross-sectional dimension in the deployed state. 
     18. The pulmonary embolism treatment device of example 17 wherein the flow restoration portions comprise cylindrical portions and the first cross-sectional dimension comprises a first diameter in the deployed state, and the capture portions comprise disk-like projections having a second diameter greater than the first diameter in the deployed state. 
     19. The pulmonary embolism treatment device of any of examples 11-18 wherein the flow restoration portion(s) have an expansion ratio from the undeployed state to the deployed state from 1:4 to 1:8. 
     20. The pulmonary embolism treatment device of any of examples 11-18 wherein the flow restoration portion(s) have an expansion ratio from the undeployed state to the deployed state from 1:5 to 1:7. 
     21. The pulmonary embolism treatment device of any of examples 11-20 wherein the first elongated member comprises an outer tube and the second elongated member comprises an inner tube within the outer tube. 
     22. The pulmonary embolism treatment device of any of examples 11-20 wherein the first elongated member comprises an outer tube and the second elongated member comprises a coil within the outer tube. 
     23. The pulmonary embolism device of any of examples 11-20 wherein the first elongated member comprises an outer coil and the second elongated member comprises an inner coil. 
     24. The pulmonary embolism treatment device of any of examples 11-23 wherein the flow restoration portion(s) and the capture elements comprise a self-expanding braided material. 
     25. The pulmonary embolism treatment device of any of examples 11-24 wherein the outer elongated member is configured to slide distally with respect to the inner elongated member to move the expansion member from the undeployed state to the deployed state. 
     26. The pulmonary embolism treatment device of any of examples 11-25, further comprising a guide catheter having a shaft with a distal end and an expandable guide member at the distal end of the shaft, wherein the shaft has a lumen configured to receive the expandable member in the undeployed state. 
     27. The pulmonary embolism treatment device of example 26 wherein the expandable guide member comprises radially expandable mesh. 
     28. The pulmonary embolism treatment device of example 27 wherein the radially expandable mesh comprises a braided material. 
     29. The pulmonary embolism treatment device of any of examples 26-28 wherein the expandable guide member has a funnel shape. 
     30. The pulmonary embolism treatment device of any of examples 26-29 wherein at least a portion of the expandable guide member is permeable to allow blood to flow through the expandable guide member when the expandable guide member is expanded. 
     31. The pulmonary embolism treatment device of any of examples 26-29 wherein the expandable guide member has a non-permeable portion at the distal end of the shaft and a permeable portion extending distally from the non-permeable portion. 
     32. A pulmonary embolism treatment device, comprising:
         an elongated member having a distal end;   an expansion portion having a proximal end attached to the distal end of the elongated member, and the expansion portion having a distal end; and   an expandable member having a proximal portion attached to the distal end of the elongated member and a distal portion attached to the distal end of the expansion portion, the expandable member having at least one of flow restoration portion and a plurality of capture elements arranged such that the capture elements are separated by individual flow restoration portion, wherein the flow restoration portion and the capture elements are configured to move from a low-profile undeployed state sized to fit within a delivery catheter to a deployed state in which (a) the flow restoration portion has a first cross-sectional dimension greater than that of the low-profile state that defines a flow channel through the device and (b) the capture elements project outwardly from the flow restoration portion, and wherein the expansion portion is stretched from a normal state when the expandable member is in the undeployed state such that the expansion portion is configured to axially contract the expandable member from the undeployed state to the deployed state.       

     33. A method of treating a pulmonary embolism, comprising:
         delivering an embolectomy device through the heart to a pulmonary embolism that at least partially restricts blood flow through a pulmonary vessel, wherein the embolectomy device has a plurality of capture elements separated by an expandable cylindrical section;   deploying the embolectomy device within the pulmonary embolism by expanding the cylindrical section into the pulmonary embolism so that the cylindrical section forms an expanded flow channel through the pulmonary embolism and thereby restores blood flow through the pulmonary embolism and by expanding the capture elements to a greater extent than the cylindrical section so that at least a portion of the pulmonary embolism is captured the capture elements;   moving the embolectomy device and at least a portion of the pulmonary embolism along the pulmonary vessel; and   withdrawing the embolectomy device and at least a portion of the pulmonary embolism from the pulmonary vessel.       

     34. The method of example 33 wherein deploying the embolectomy device comprises expanding a plurality of radial extendable capture elements of the embolectomy device. 
     35. The method of example 34, wherein at least one of the plurality of radial extendable capture elements is expanded distal relative to the pulmonary embolism. 
     36. The method of example 33, further comprising applying vacuum while withdrawing the embolectomy device. 
     37. The method of example 36, wherein withdrawing the embolectomy device includes urging the portion of the pulmonary embolism into a funnel catheter. 
     38. The method of example 37, wherein deploying the embolectomy device comprises expanding the device such that a surface area of the embolectomy device expands within a range of at least 200% to 400% of the surface area of a uniformly cylindrical device. 
     39. The method of example 33 wherein deploying the embolectomy device comprises expanding the generally cylindrical section by 400% to 800% of its diameter in the undeployed state. 
     40. The method according to and of examples 33-39 wherein deploying the embolectomy device comprises expanding a braided material into a preset shape having a plurality of radially extending disk-like capture portions that define the capture elements. 
     Although the invention has been described in terms of particular embodiments and applications, one of ordinary skill in the art, in light of this teaching, can generate additional embodiments and modifications without departing from the spirit of or exceeding the scope of the exampled invention. Accordingly, it is to be understood that the drawings and descriptions herein are proffered by way of example to facilitate comprehension of the invention and should not be construed to limit the scope thereof.