A system for treating vasculature of a patient includes a microcatheter extending through an optional aspiration catheter, and a guidewire subassembly extending through and beyond the microcatheter. The guidewire subassembly consists essentially of a (i) guidewire core having a narrowed portion, (ii) a fluid transport element coupled to and extending around the narrowed portion of the guidewire core, the fluid transport element defining at least one inlet opening and at least one outlet opening spaced from the inlet opening along a portion of its length, with a fluid flow path being defined between the fluid transport element and the microcatheter, and (iii) a conical seal interposed between the guidewire core and the support element for sealing therebetween and ensuring that infusate within the microcatheter is directed into the blood vessel through the inlet opening(s), the fluid flow path, and the outlet opening(s).