Systems and methods for injection and aspiration

A method for catheter-based aspiration, comprising:

• providing a catheter having a distal portion configured for insertion within a blood vessel of a subject, the catheter comprising:
• a first lumen having a distal opening at the distal portion of the catheter;
• a second lumen having a distal end at the distal portion of the catheter;
• and
• an orifice located at or near the distal end of the second lumen, the orifice configured to direct liquid into the first lumen at or near the distal opening of the first lumen;
• and
• actuating an injector in a non-uniform manner to cause a pulsatile pressure of a liquid in the second lumen as the liquid is injected through the second lumen, wherein actuating the injector in a non-uniform manner comprises automatically injecting in an oscillating or variable manner to repeatedly displace a plunger in an interior of a barrel in a first direction along a longitudinal displacement axis by an increment, followed by movement of the plunger in a second direction, opposite the first direction.