Mechanically locking blood clot filter

Abstract

A blood clot filter particularly suited for filtering blood clots from blood circulating through the inferior vena cava is composed of a number of peripheral wires joined at one end by a first connector and also joined approximately at their middle portions by a second connector. The wire portions extending between the two connectors form a filter mesh, and the wire portions extending between the second connector and the free ends form filtering legs which anchor the filter. The free ends have recurved hooks for radial engagement with a blood vessel. The filter mesh is formed by mechanically approximating the two connectors resulting in the formation of overlapping loops of wire. A central core wire is fixedly secured to one of the two connectors and slidingly extends through the second of the two connectors. The central core wire is retracted to slide the two connectors together. A lock device prevents the two connectors from sliding back apart. The wire strands may initially be substantially straightened in order to permit insertion of the filter into the lumen of an angiographic catheter. The catheter is positioned at a predetermined site within the vessel using standard percutaneous angiographic techniques from the groin or neck. A pusher catheter extending within a delivery catheter pushes the filter out of the delivery catheter and into the lumen of the blood vessel. A retractor cable extends through the pusher catheter and is releasably coupled to the central core wire for retracting the same. Once the filter has been delivered into the blood vessel and the filter mesh mechanically formed, the legs are released to anchor the filter in position, and the pusher wire is disconnected.