Blood flow restoration and thrombus management methods

Abstract

Systems, methods, and devices for the treatment of acute ischemic stroke that provide immediate blood flow restoration to a vessel occluded by a clot and, after reestablishing blood flow, address the clot itself. Immediate blood flow restoration advantageously can facilitate natural lysis of the clot and also can reduce or obviate the concern for distal embolization due to fragmentation of the clot. Several embodiments of the invention provide for progressive, or modular, treatment based upon the nature of the clot. For example, the progressive treatment can comprise a three-step progressive treatment process that includes immediate restoration of blood flow, in-situ clot management, and/or clot removal depending on the particular circumstances of the treatment. The in-situ clot management can include, for example, lysis and maceration. The progressive, or modular, treatment can be provided by a system or kit of one or more treatment devices.

1 . A thrombus management method, comprising:
 identifying a cerebral vessel having a thrombus;   inserting a guidewire into the cerebral vessel and past the thrombus;   inserting a microcatheter over the guidewire to a location of the thrombus;   placing a distal end of the microcatheter 0.5 to 10 millimeters past the thrombus;   inserting an expandable tip assembly comprising a self-expanding member through the microcatheter;   advancing the expandable tip assembly within the microcatheter such that a distal end of the self-expanding member is proximate the distal end of the microcatheter;   retracting the microcatheter, thereby causing the self-expanding member to expand across at least a portion of the length of the thrombus,   wherein said expansion compresses the thrombus against a wall of the cerebral vessel,   wherein said compression of the thrombus restores blood flow within the cerebral vessel, and   wherein said restored blood flow facilitates natural lysis of the thrombus;   macerating the thrombus by moving the microcatheter to expand and compress the self-expanding member, thereby facilitating mechanical lysis and fragmentation of the thrombus to release embolic particles;   wherein the embolic particles flow in the direction of the blood flow and are not captured by any distal embolic protection device but are instead lysed through the natural lysis process due to the restored blood flow;   engaging a remaining portion of the thrombus after said maceration; and   extracting said remaining portion of the thrombus from the blood vessel.   
     
     
         2 . The thrombus management method of  claim 1 , wherein moving the microcatheter to expand and compress the self-expanding member comprises resheathing the self-expanding member within the microcatheter by advancement of the microcatheter and unsheathing the self-expanding member from the microcatheter by retraction of the microcatheter. 
     
     
         3 . The thrombus management method of  claim 1 , wherein inserting a microcatheter over the guidewire to a location of the thrombus comprises inserting the microcatheter through the thrombus or to the side of the thrombus. 
     
     
         4 . The thrombus management method of  claim 1 , wherein engaging the remaining portion of the thrombus and extracting the remaining portion of the thrombus are performed by the expandable tip assembly. 
     
     
         5 . The thrombus management method of  claim 1 , wherein engaging the remaining portion of the thrombus and extracting the remaining portion of the thrombus are performed by a second expandable tip assembly configured for thrombus removal, wherein said second expandable tip assembly is inserted into the microcatheter after removing the first expandable tip assembly from the microcatheter after macerating the thrombus. 
     
     
         6 . The thrombus management method of  claim 1 , wherein said expandable tip assembly is selected based, at least in part, on a vessel diameter of the identified blood vessel. 
     
     
         7 . The thrombus management method of  claim 1 , further comprising delivering one or more agents configured to promote thrombus adhesion or platelet activation to a location of the thrombus through or over the expandable tip assembly. 
     
     
         8 . The thrombus management method of  claim 1 , wherein said natural lysis and said maceration decreases the size of the thrombus by between about 10% and about 30%. 
     
     
         9 . The thrombus management method of  claim 1 , wherein the self-expanding member is expanded from a location within the thrombus, thereby imploding the thrombus from within. 
     
     
         10 . The thrombus management method of  claim 1 , wherein blood flow is restored in less than two minutes from deployment of the self-expanding member within the thrombus. 
     
     
         11 . A thrombus management method, comprising:
 identifying a blood vessel having a thrombus;   inserting a guide wire into the blood vessel and past the thrombus;   inserting a microcatheter over the guidewire to a location of the thrombus;   positioning a distal end of the microcatheter past the thrombus;   inserting an expandable tip assembly comprising a proximal elongate member and a distal self-expanding member through the microcatheter;   advancing the expandable tip assembly within the microcatheter such that a distal end of the self-expanding member is proximate the distal end of the microcatheter;   retracting the microcatheter in a proximal direction, thereby causing the self-expanding member to expand;   wherein said expansion of the self-expanding member compresses the thrombus against a wall of the blood vessel;   wherein said compression of the thrombus restores blood flow within the blood vessel;   wherein said restored blood flow facilitates natural lysis of the thrombus; and   macerating the thrombus by resheathing the self-expanding member within the microcatheter and unsheathing the self-expanding member from the microcatheter through advancement and retraction of the microcatheter, thereby facilitating mechanical lysis and fragmentation of the thrombus to release embolic particles;   wherein the embolic particles flow in the direction of the blood flow and are lysed through natural lysis due to the restored blood flow.   
     
     
         12 . The thrombus management method of  claim 11 , further comprising engaging any remaining thrombus material and removing said any remaining thrombus material with the expandable tip assembly. 
     
     
         13 . The thrombus management method of  claim 11 , further comprising removing the expandable tip assembly and inserting a second expandable tip assembly into the microcatheter, the second expandable tip assembly having a self-expanding member with cells having a cell size configured to increase penetration of remaining thrombus material into the cells to facilitate capture of the remaining thrombus material. 
     
     
         14 . The thrombus management method of  claim 13 , further comprising engaging the remaining thrombus material and removing the remaining thrombus material with the second expandable tip assembly. 
     
     
         15 . The thrombus management method of  claim 14 , wherein the remaining thrombus material comprises a hard fibrin core of the thrombus. 
     
     
         16 . The thrombus management method of  claim 11 , wherein said natural lysis and said maceration decreases the size of the thrombus by between about 10% and about 30%. 
     
     
         17 . A thrombus management method for the treatment of ischemic stroke, the method comprising:
 identifying an occluded blood vessel having a thrombus;   selecting an expandable tip assembly based, at least in part, on a diameter of the identified occluded blood vessel, the expandable tip assembly comprising a proximal elongate member and a distal self-expanding member;   inserting the selected expandable tip assembly within the occluded vessel through a microcatheter such that the self-expanding member is positioned at a location of the thrombus in a non-expanded configuration;   retracting the microcatheter, thereby causing the self-expanding member to expand to an expanded configuration,   wherein said expansion of the self-expanding member compresses the thrombus against a wall of the blood vessel,   wherein said compression of the thrombus restores blood flow within the blood vessel,   wherein said restored blood flow facilitates natural lysis of the thrombus;   engaging at least a portion of remaining thrombus material with the expandable tip assembly; and   removing the at least a portion of remaining thrombus material with the expandable tip assembly.   
     
     
         18 . The thrombus management method of  claim 17 , further comprising macerating the thrombus by resheathing the self-expanding member within the microcatheter and unsheathing the self-expanding member from the microcatheter by moving the microcatheter, thereby facilitating mechanical lysis and fragmentation of the thrombus. 
     
     
         19 . The thrombus management method of  claim 17 , wherein the blood vessel comprises a cerebral artery, and wherein the proximal elongate member comprises a flexible distal portion configured to navigate curved portions of cerebral vasculature during delivery to the cerebral artery. 
     
     
         20 . The thrombus management method of  claim 17 , further comprising removing all of the remaining thrombus material.