Methods and apparatus for obtaining endoluminal access are provided
comprising a steerable endoluminal guide having a variable pivot for
altering steering dynamics. In one variation, variable pivoting is
achieved by advancing a member having a hard or substantially rigid
section to various depths within a lumen of the guide. The hard section
resists deformation, thereby reducing or precluding pivoting of the guide
proximal of the distal-most depth of hard section insertion. In another
variation, the guide comprises one or more pivot wires that terminate at
a segment of the guide disposed proximal of the guide's distal outlet. In
such a variation, the steering pivot of the guide may be altered by
applying tension to at least one pivot wire, while concurrently applying
tension to a steering wire that terminates more distally than the pivot
wire, and that is radially offset from the pivot wire about the
circumference of the guide. In another variation, one or more stiffening
elements are translated over or alongside one or more steering wires to
alter the guide's pivot.