The invention is directed to methods and apparatus for centering a microcatheter within a vasculature. In one aspect, the methods and apparatus can be used to support centering and to facilitate a guidewire to cross through a chronic total occlusion. In one embodiment, the catheter apparatus includes: a microcatheter having a lumen, a distal opening and a distal end； one or more guidewires for passing through the lumen of the microcatheter； an inner shaft having a lumen, a distal opening and a distal end for passing the inner shaft over the microcatheter； an outer shaft having a lumen, a distal opening and a distal end for passing the outer shaft over the inner shaft； and a self-expandable scaffold structure disposed towards the distal end of the inner shaft. The self-expandable scaffold structure is preferably non-occluding thereby allowing blood to flow through the scaffold. Preferably, the inner shaft and microcatheter are capable of being independently operable.
