The proximal portion may be about 90 cm to about 130 cm in length, depending on the length of the distal portion. 

[0052] In some cases, a clinician may steer catheter 12 through the vasculature of a patient by pushing or rotating the hub and/or the proximal portion of catheter 12 to navigate the distal portion of catheter 12 through the vasculature of a patient. The clinician may apply torque to the hub and/or the proximal portion of catheter 12 to rotate the distal portion of catheter 12. In some examples, as will be discussed further below, a clinician may guide catheter 12 using a first hand while controlling fluid flow from catheter 12 with fluid flow switch 14 and sensing fluid from catheter 12 with fluid flow sensor 16 using a second hand. 

[0053] Aspiration system 10 includes fluid pump 18 downstream of fluid flow sensor 16. Fluid pump 18 is configured to create a negative pressure (i.e., vacuum or suction) on catheter 12, e.g., to draw fluid through an inner lumen of catheter 12 into discharge fluid reservoir 34. For example, fluid pump 18 may include a port configured to couple to aspiration tubing 30, such that the negative pressure created by fluid pump 18 may be applied to the port and through aspiration tubing 30 and other portions of a fluid pathway between aspiration tubing 30 and an inner lumen of catheter 12. As an example of operation of fluid pump 18, when the one or more distal openings 36 of catheter 12 are not blocked, fluid pump 18 may draw fluid from catheter 12 into a discharge fluid reservoir 34 through aspiration tubing 26, 28, 30, and through switch 14 and fluid flow sensor 16. As another example, when the one or more distal openings 36 are partially or wholly blocked, fluid pump 18 may draw fluid from catheter 12 at a reduced flow rate or, in some instances in which blockage is complete, draw no fluid at all. However, even when the one or more distal openings 36 are blocked, fluid pump 18 may be configured to continue to create a vacuum on catheter 12. A variety of pumps may be used for fluid pump 18 including, but not limited to, positive displacement pumps, centrifugal pumps, and the like. 

[0054] In some examples, fluid pump 18 may be configured for bi-directional operation. For example, fluid pump 18 may be configured to create a negative pressure that draws fluid from catheter 12 in a first flow direction and create a positive pressure that pumps fluid to catheter 12 and through an inner lumen of catheter 12 in a second, opposite flow direction. As an example of this bi-directional operation, an operator of aspiration system 10 may operate pump 18 to pump an aspiration/irrigating fluid, such as saline, from an aspiration fluid reservoir 32 to flush and/or prime catheter 12 (e.g., an 

