Catheter systems and methods for their use in the treatment of calcified vascular occlusions

Catheter systems and methods for their use in enhancing fluid flow through a vascular site occupied by a vascular occlusion are provided. The subject catheter systems include at least an aspiration catheter and at least one of a total occlusion insert catheter and a partial occlusion insert catheter, where the insert catheters are capable of being slidably moved in the lumen of the aspiration catheter. In practicing the subject methods, a surface of the vascular occlusion is flushed with an acidic dissolution fluid using the subject catheter systems for a period of time sufficient for fluid flow through the vascular site to be enhanced, e.g. increased or established. The subject catheter systems and methods find use in the treatment of a variety of different vascular diseases characterized by the presence of calcified vascular occlusions, including peripheral and coronary vascular diseases.