A flexible, steerable intravascular catheter includes an elongate flexible shaft having a heterogeneous or multi-zone stiffness profile or structure. A first or distal portion of the catheter shaft may have a substantially constant or distinct stiffness or flexibility, a second, intermediate or transition section is proximal relative to, and less flexible than, the first section, and a third section is proximal relative to, and also less more flexible than, the first section. The third section also includes a substantially constant or distinct stiffness or flexibility. The flexibility or stiffness of the second section varies along its length, e.g., in a substantially linear, step-like or ramp-like manner to provide a smooth or gradual transition between the stiffness of the first or distal section and the flexibility or stiffness of the third or proximal section.
