Methods for easy, atraumatic access to areas of the vasculature that are otherwise difficult to access, using steerable guide catheters constructed with components that are selected to provide optimal navigability, torque transfer, and push ability for a variety of typical percutaneous access routes. The catheter wall thickness in the deflecting segment of the guide catheter is about 1 French (⅓ mm) or less, and includes a slotted deflection tube, and this construction allows a very tight turning radius which in turn enables guide catheter access to regions of the vasculature that are otherwise inaccessible.