Aspiration catheter systems and methods of use

A method of performing a medical procedure in an intracranial vessel of a patient, the method comprising:

• inserting a guide sheath into a blood vessel, the guide sheath comprising a lumen extending between a proximal end region and a distal end region of the guide sheath, the distal end region of the guide sheath having an opening in communication with the lumen of the guide sheath;
• positioning the guide sheath such that the distal end region of the guide sheath is positioned at least to a level of a common carotid artery;
• inserting a first catheter through the lumen of the guide sheath, the catheter comprising:
• a flexible distal luminal portion having a proximal end, a proximal opening, a distal end, a distal opening, and a lumen extending between the proximal opening and the distal opening;
• and
• a proximal extension extending proximally from a point of attachment adjacent the proximal opening to a tab positioned on a proximal end of the proximal extension, wherein the proximal extension is configured to control movement of the catheter and to prevent over-insertion of the first catheter, and wherein at least a portion of the proximal extension has an outer diameter that is smaller than an outer diameter of the flexible distal luminal portion;
• and
• advancing the first catheter such that the distal end of the flexible distal luminal portion is advanced through the opening of the guide sheath and beyond the distal end region of the guide sheath to reach an intracranial vessel,
• wherein the tab is positioned relative to the proximal opening of the flexible distal luminal portion to prevent over-insertion of the first catheter relative to the guide sheath allowing the distal end of the flexible distal luminal portion to reach the intracranial vessel and maintaining the proximal opening within the lumen of the guide sheath.