| 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. |