US Patent 11400255 Aspiration catheter systems and methods of use

A method of performing a medical procedure in a cerebral vessel including advancing a guide sheath into an internal carotid artery; advancing a catheter within a lumen of the guide sheath until a distal end of the catheter is adjacent to an embolus in a cerebral vessel; activating a vacuum source to create a vacuum in a lumen of the catheter; and cyclically controlling the vacuum applied with a valve. The vacuum is cyclically controlled by opening the valve for a first time period, closing the valve for a second time period longer than the first time period, opening the valve for a third time period shorter than the first time period, then closing the valve for a fourth time period greater than the first time period, and repeating for at least 40 cycles.