Recoilable thrombosis filtering device and method

Abstract

A thrombosis filter which can be securely affixed at a selected location in the vascular system of a patient and removed when no longer required. A first embodiment of the thrombosis filter includes a plurality of struts having a first grouping and a second grouping. The first grouping of struts and the second grouping of struts radiate in opposite directions. The free ends of the struts include anchoring elements which anchor into the walls of a blood vessel. At least one grouping of struts is comprised of a shape memory material. When these struts are at body temperature, their free ends engage the wall of the blood vessel. When the temperature of the shape memory alloy struts is selectively varied from body temperature, the struts retract into the body portion of the thrombosis filter. A second embodiment of the thrombosis filter includes a generally cylindrical anchoring portion, and a generally conical filtering portion, the filtering portion includes a plurality of elongated strands interwoven to create a pattern of cells. These strands extend beyond the filtering portion to comprise the anchoring portion. These strands are made of a shape memory material. At body temperature, the thrombus filter takes on an expanded shape. At a temperature other than body temperature, the thrombus filter assumes a contracted shape. When the thrombus filter assumes a contracted shape, the anchoring portion retracts away from the walls of the blood vessel. A method is also disclosed for removing the thrombus filter from a blood vessel. The method comprises changing the temperature of the thrombus filter so that it assumes a retracted shape then pulling the thrombus filter inside the lumen of a retrieval catheter.

1 - 24 . (canceled)  
     
     
         25 . (new) a thrombus filter element for placement within a blood vessel lumen defined by a blood vessel wall comprising: 
 a plurality of struts having a first grouping and a second grouping, wherein the first grouping and the second grouping radiate in generally opposing directions, the radiating struts having free ends, the second grouping further having shape-memory material; and    a plurality of anchoring elements disposed on at least a plurality of the free ends of the plurality of struts, wherein the anchoring elements engage the blood vessel wall;    wherein the struts of the second grouping of struts shorten when a temperature of the shape memory material changes from body temperature.    
     
     
         26 . The thrombosis filter of  claim 25 , wherein the struts of the second grouping of struts shorten when the temperature of the shape memory material is lower than body temperature.  
     
     
         27 . The thrombosis filter of  claim 25 , wherein the struts of the second grouping of struts shorten when the temperature of the shape memory material is higher than body temperature.  
     
     
         28 . The thrombosis filter of  claim 25 , wherein the shape-memory material of said plurality of struts comprises a NiTi alloy.  
     
     
         29 . The thrombosis filter of  claim 25 , wherein the anchoring elements comprise a NiTi alloy.  
     
     
         30 . The thrombosis filter of  claim 25 , wherein the first grouping of said plurality of struts comprise a NiTi alloy.  
     
     
         31 . The thrombosis filter of  claim 25 , wherein the first grouping and second grouping of the plurality of struts attach to a body portion.  
     
     
         32 . The thrombosis filter of  claim 31 , wherein the body portion includes an aperture and the second grouping of the struts radiate from within the aperture.  
     
     
         33 . The thrombosis filter of  claim 32 , wherein the second grouping of the plurality of struts radiate outward from the aperture when the temperature of the shape-memory material is generally body temperature.  
     
     
         34 . The thrombosis filter of  claim 32 , wherein the second grouping of the plurality of struts retract within said aperture when the temperature of the shape-memory material is generally lower than body temperature.  
     
     
         35 . The thrombosis filter of  claim 32 , wherein the second grouping of the plurality of struts retract within the aperture when the temperature of the shape-memory material is generally higher than body temperature.  
     
     
         36 . The thrombosis filter of  claim 31 , wherein the body portion further comprises a hooking means, wherein the hooking means comprises a conducting material.  
     
     
         37 . The thrombosis filter of  claim 36 , wherein the hooking means allows for attachment of an electrode, the electrode capable of inducing a current through the hooking means, the body portion, and the plurality of struts.  
     
     
         38 . The thrombosis filter of  claim 37 , wherein the current is heat, the heat conducts through the hooking means, the body portion, and the plurality of struts comprising shape-memory material.  
     
     
         39 . A thrombosis filter element for placement within a blood vessel defined by a blood vessel wall comprising: 
 a body portion from which a plurality of struts radiate, the plurality of struts each having a first section wherein the first section of the plurality of struts attaches to the body portion, the plurality of struts each further having a second section wherein at least a portion of the plurality of struts are interconnected, the plurality of struts comprising a shape-memory alloy; and    a plurality of anchoring elements connected to the plurality of struts.    
     
     
         40 . The thrombosis filter of  claim 39 , wherein the shape-memory material of the plurality of struts comprises a NiTi alloy.  
     
     
         41 . The thrombosis filter of  claim 39 , wherein the anchoring elements comprise a NiTi alloy.  
     
     
         42 . The thrombosis filter of  claim 39 , wherein the plurality of struts radiate toward the blood vessel wall when the temperature of the shape-memory material is generally body temperature.  
     
     
         43 . The thrombosis filter of  claim 39 , wherein the plurality of struts retract from the blood vessel wall when the temperature of the shape-memory alloy material is generally lower than body temperature.  
     
     
         44 . The thrombosis filter of  claim 39 , wherein the plurality of struts retract from the blood vessel wall when the temperature of the shape-memory alloy material is generally higher than body temperature.  
     
     
         45 . A thrombus filter element for placement within a blood vessel lumen defined by a blood vessel wall comprising: 
 a body portion from which a plurality of struts radiate, each of the plurality of struts having an attachment end that attaches to said body portion and a free end that radiates outward from the body portion;    a plurality of anchoring elements connected to the plurality of struts; and    a ring attached to each of the plurality of struts proximate the free end of each strut, the ring comprising a shape-memory alloy changeable from an expanded position in which the plurality of anchoring elements engage the vessel wall to a contracted position in which the plurality of anchoring elements disengage from the vessel wall.    
     
     
         46 . The thrombosis filter of  claim 45 , wherein the shape-memory alloy comprises a NiTi alloy.  
     
     
         47 . The thrombosis filter of  claim 45 , wherein the plurality of anchoring elements engage the blood vessel wall when a temperature of the shape-memory material is generally body temperature.  
     
     
         48 . The thrombosis filter of  claim 45 , wherein the plurality of anchoring elements disengage from the blood vessel wall when a temperature of the shape-memory alloy material is generally lower than body temperature.  
     
     
         49 . The thrombosis filter of  claim 45 , wherein the plurality of anchoring elements disengage from the blood vessel wall when a temperature of the shape-memory alloy material is generally higher than body temperature.  
     
     
         50 . A method of placing a thrombosis filter element within a blood vessel lumen, defined by a blood vessel wall, the method comprising steps of: 
 providing a thrombosis filter having a plurality of struts, wherein a portion of the struts comprise a shape-memory material, the struts comprising the shape-memory material capable of modifying their preexisting configuration by altering the temperature of said material;    advancing the thrombosis filter along said vessel lumen of the patient until the thrombosis filter is disposed in the selected portion of the vessel lumen;    providing a means for inducing a current in the shape-memory material; and    altering the temperature of the shape-memory material with the current resulting in the struts engaging the vessel wall.    
     
     
         51 . The method according to  claim 50 , wherein the means for inducing a current in the shape-memory material is an electrode.  
     
     
         52 . The method according to  claim 50 , wherein the current is heat.