Patent ID: 8105349

Claim:
A removable filter having a collapsed state and an expanded state for capturing thrombi in a blood vessel, the filter comprising: a plurality of primary struts extending distally, each primary strut in the expanded state extending from a primary strut first end to an anchoring hook, each primary strut having a first diameter, each primary strut extending arcuately along a longitudinal axis and linearly radially, each primary strut including a first curved portion and a second curved portion, the first curved portion extending from the first end and configured to bend away from the longitudinal axis, the second curved portion extending from the first curved portion and configured to bend toward the longitudinal axis, the second curved portion terminating at the anchoring hook, the plurality of primary strut first ends being attached together along the longitudinal axis, wherein the anchoring hooks face inwardly toward the longitudinal axis when the filter is in the collapsed state; and a plurality of secondary struts extending distally, each secondary strut in the expanded state extending from a secondary strut first end to a free end without a hook, each secondary strut extending arcuately along the longitudinal axis and linearly radially, the primary and secondary struts being formed from wire having a round cross section, each secondary strut having a second diameter smaller than the first diameter of the primary struts, each secondary strut including a first arc and a second arc, the first arc extending from the first end and in a direction away from the longitudinal axis, the second arc extending from the first arc and in a direction toward the longitudinal axis, the second arc terminating at the free end, the plurality of secondary strut first ends being attached together along the longitudinal axis, the plurality of secondary struts centralizing the filter in the expanded state in the blood vessel; wherein the first arcs of the secondary struts are disposed radially inward from the first curved portions of the primary struts when the filter is in the expanded state.