Patent ID: 7314477

Claim:
A filter delivery system comprising: a vascular filter having a plurality of elongate appendages for engaging a vessel wall; and a filter delivery unit for delivery of the filter including, an elongate pusher wire having a free end to engage a portion of the filter; a flexible hinge formed in said pusher wire and spaced from said free end, said pusher wire having an end section formed in said pusher wire extending between said flexible hinge and said free end, said flexible hinge including a cross sectional area of reduced size relative to both said pusher wire and said pusher wire end section, and said flexible hinge being formed to permit said pusher wire end section to pivot about said flexible hinge to move said free end radially in all directions; and wherein said pusher wire is formed of thermal shape memory material having a temperature transformation level below which the material is in a martensitic state and relatively pliable and above which the material is normally in an austenitic state and is substantiality rigid, said material exhibiting stress sensitivity which can cause the material to transform to the martensitic state in response to stress while the temperature of the material remains above the temperature transformation level, said cross sectional area of reduced size forming said hinge being formed to receive a concentration of stress applied to said pusher wire end section.