Aspiration thrombectomy system and methods for thrombus removal with aspiration catheter

A clot removal system, comprising:

• a catheter having a distal end and defining a lumen filled with a liquid column having a proximal portion and a distal portion;
• a controllable vacuum valve;
• a vacuum source fluidically connected to the vacuum valve;
• a controllable vent valve having a vent liquid input;
• a vent fluid source containing a vent liquid and fluidically connected to the vent valve to retain the vent liquid at the vent fluid input;
• a manifold connected to the catheter, to the vacuum valve, and to the vent valve, the manifold fluidically connecting the proximal portion of the liquid column in the lumen:
• to the vacuum source through the vacuum valve;
• and
• to the vent fluid source through the vent valve;
• a controller connected to the vacuum valve and the vent valve and configured to selectively open and close the vacuum valve and the vent valve such that:
• responsive to opening the vacuum valve, the vacuum source is fluidically connected to the liquid column in the lumen;
• and
• responsive to opening the vent valve, the vent fluid source is fluidically connected to the liquid column in the lumen,
• the controller configured to cyclically open and close the vacuum valve and the vent valve in a repeated cycle comprising a double-closed state in which the vacuum valve is closed and the vent valve is closed to:
• change a level of vacuum at the distal end;
• and
• prevent forward flow of the distal portion out from the distal end during each cycle, and
• a time of the double-closed state is no greater than approximately 30 ms.