Embolic obstruction retrieval devices and methods

An embolic obstruction retrieval device comprising:

• an elongate self-expandable member expandable from a first delivery position to a second placement position, in the first delivery position the expandable member being in an unexpanded position and having a nominal first diameter and in the second position the expandable member being in a radially expanded position and having a second nominal diameter greater than the first nominal diameter, the expandable member comprising a plurality of generally longitudinal undulating elements with adjacent undulating elements being interconnected in a manner to form a plurality of diagonally disposed cell structures, the expandable member having a proximal end portion with a first length and an elongate cylindrical main body portion with a second length, the elongate cylindrical main body portion located distal to the proximal end portion, the elongate cylindrical main body portion comprising at least a first circumferential row of cell structures that extends diagonally and circumferentially around a longitudinal axis of the expandable member, a second circumferential row of cell structures located distal to and interconnected with the first circumferential row of cell structures that extends diagonally and circumferentially around the longitudinal axis of the expandable member, a third circumferential row of cell structures located distal to and interconnected with the second circumferential row of cell structures that extends diagonally and circumferentially around the longitudinal axis of the expandable member, a fourth circumferential row of cell structures located distal to and interconnected with the third circumferential row of cell structures that extends diagonally and circumferentially around the longitudinal axis of the expandable member, the proximal end portion comprising multiple rows of cell structures with none of the multiple rows of cell structures extending circumferentially around the longitudinal axis of the expandable member, the second length of the elongate cylindrical main body portion being between 2.5 and 3.5 times greater than the first length of the proximal end portion, the outer-most cell structures in the proximal end portion having proximal-most wall segments that form first and second rail segments that each extend from a position at or near a proximal-most end of the expandable member to a position at or near a proximal end of the cylindrical main body portion, when the expandable member is cut and laid flat on a surface at least the first rail segment is substantially straight;
• and
• a first proximally extending elongate flexible wire connected to the proximal-most end of the expandable member.