Patent ID: 8043322

Claim:
A removable filter for capturing thrombi in a blood vessel, the filter comprising: a plurality of primary struts having first ends attached together along a longitudinal axis, each primary strut having a first length and extending arcuately along the longitudinal axis and linearly relative to a radial axis from the first end to an anchoring hook configured to anchor into a vessel wall of the blood vessel, each primary strut having an S-shaped arcuate segment including a first curved portion and a second curved portion, the first curved portion extending from the first end and softly bending away from the longitudinal axis, the second curved portion extending from the first curved portion and softly bending toward the longitudinal axis and terminating at the anchoring hook, the primary struts being configured to move between an expanded state for engaging the anchoring hooks with the blood vessel and a collapsed state within a tube for filter retrieval or delivery, each primary strut being configured to cross another primary strut along the longitudinal axis in the collapsed state such that each anchoring hook faces inwardly toward the longitudinal axis and away from an inner wall of the tube and the blood vessel wall for filter retrieval or delivery; and a plurality of secondary struts having connected ends attached together along the longitudinal axis, each secondary strut having a second length, the secondary struts extending from the connected ends and terminating at free ends without a hook to centralize the filter in the expanded state in the blood vessel, the free ends avoiding contact with other secondary struts and primary struts, each secondary strut extending arcuately along the longitudinal axis and linearly relative to a radial axis from the connected end to the free end, each secondary strut having an S-shape including a first arc and a second arc, the first arc extending from the connected end away from the longitudinal axis, the second arc extending from the first arc toward the longitudinal axis and terminating at the free end, wherein the length of the filter is defined by the first length of the primary struts, wherein the first arcs of the secondary struts are provided inside the first curved portions of the primary struts when the filter is in the expanded state.