pitch of the helical struts. [0044]FIG. 7 is a perspective view of an alternative basket having protrusions and/or circumferential indentations to inhibit axial sliding of occlusive material during shearing. [0045]FIG. 8 is a perspective view of yet another alternative basket having circumferential proximal and/or distal web members between struts to inhibit severing of valves and other structure